From 34a2a155d21b5a8bd286a86b18967c242d7871a8 Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Thu, 11 Jun 2026 02:27:23 -0700
Subject: [PATCH 01/19] Add graph review app for UnresolvedArenaEnvGraphSpec

Adds a Streamlit-based live editor for reviewing and editing
UnresolvedArenaEnvGraphSpec YAMLs. The review tool renders:
- A mermaid.js spatial graph of initial-state constraints with
  anchor highlighting, task-constraint dashed edges, and
  objectReference dotted edges
- A task table (index, kind, description, params)
- A node card grid with type badges and per-node YAML stanzas

The YAML editor auto-renders when the spec is valid and changed.
Node cards display a two-letter placeholder thumbnail by default.

Also adds YAML round-trip serialization to ArenaEnvGraphSpec and
moves assert_unique_ids/assert_references_exist to __post_init__
so validation fires on every load-from-yaml/dict path.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../review_app.py                             | 275 +++++++++++
 .../review_graph.py                           | 444 ++++++++++++++++++
 .../environments/arena_env_graph_spec.py      |  12 +
 setup.py                                      |   6 +
 4 files changed, 737 insertions(+)
 create mode 100644 isaaclab_arena/agentic_environment_generation/review_app.py
 create mode 100644 isaaclab_arena/agentic_environment_generation/review_graph.py

diff --git a/isaaclab_arena/agentic_environment_generation/review_app.py b/isaaclab_arena/agentic_environment_generation/review_app.py
new file mode 100644
index 000000000..1a156190a
--- /dev/null
+++ b/isaaclab_arena/agentic_environment_generation/review_app.py
@@ -0,0 +1,275 @@
+# Copyright (c) 2025-2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""Streamlit-backed live editor for ArenaEnvInitialGraphSpec YAMLs.
+
+Wraps :func:`isaaclab_arena.agentic_environment_generation.review_graph.render_html_for_spec`
+in a two-pane Streamlit page so the user can edit the ``ArenaEnvInitialGraphSpec``
+YAML directly in the browser and see the visualization update automatically.
+
+Launch (always via the wrapper in review_graph.py — handles streamlit flags):
+    /isaac-sim/python.sh -m isaaclab_arena.agentic_environment_generation.review_graph \\
+        --yaml path/to/spec.yaml
+
+Design:
+  * Left pane — ``streamlit-ace`` YAML editor + validation badge + Save button.
+    Validation runs on every rerun (i.e. after each editor blur). When the YAML
+    is valid and has changed since the last render, the visualization updates
+    automatically — no button click required.
+  * Right pane — sandboxed iframe with the rendered review HTML.
+"""
+
+from __future__ import annotations
+
+import argparse
+import traceback
+import yaml
+from dataclasses import dataclass
+from pathlib import Path
+
+import streamlit as st
+
+from isaaclab_arena.agentic_environment_generation.review_graph import render_html_for_spec
+from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
+
+# Visualization iframe height. Tuned so the graph + tasks + node grid all
+# fit without an outer Streamlit scrollbar swallowing the inner one.
+_IFRAME_HEIGHT_PX = 1100
+
+
+# ---------------------------------------------------------------------------
+# Args + session-state init
+# ---------------------------------------------------------------------------
+
+
+def _parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument(
+        "--yaml",
+        type=Path,
+        required=True,
+        help="Path to the ArenaEnvInitialGraphSpec YAML to open in the editor.",
+    )
+    return parser.parse_args()
+
+
+@dataclass
+class _ValidationResult:
+    spec: ArenaEnvInitialGraphSpec | None
+    error: str | None
+
+    @property
+    def is_valid(self) -> bool:
+        return self.spec is not None
+
+
+def _validate_yaml_text(text: str) -> _ValidationResult:
+    try:
+        raw = yaml.safe_load(text)
+        spec = ArenaEnvInitialGraphSpec.model_validate(raw)
+        return _ValidationResult(spec=spec, error=None)
+    except Exception:
+        return _ValidationResult(spec=None, error=traceback.format_exc())
+
+
+def _initialize_state(yaml_path: Path) -> None:
+    """Seed ``st.session_state`` from disk exactly once per session.
+
+    We key off ``_yaml_path`` so that if the user passes a different YAML on
+    a Streamlit reload (rare — usually the same), we reset cleanly.
+    """
+    if st.session_state.get("_yaml_path") == str(yaml_path):
+        return
+
+    original_text = yaml_path.read_text(encoding="utf-8")
+
+    st.session_state["_yaml_path"] = str(yaml_path)
+    st.session_state["original_text"] = original_text
+    st.session_state["edited_text"] = original_text
+    # The text whose render is currently displayed. Starts == original so the
+    # first paint shows the on-disk file (and "Regenerate" is correctly
+    # disabled until the user edits something).
+    st.session_state["last_rendered_text"] = original_text
+    st.session_state["save_path"] = str(yaml_path)
+
+    initial = _validate_yaml_text(original_text)
+    if not initial.is_valid:
+        # Defensive: if the on-disk file is already broken we still want to
+        # show *something*, but we won't pre-render it. The user fixes the
+        # YAML in the editor, then hits Regenerate.
+        st.session_state["rendered_html"] = _BROKEN_PLACEHOLDER_HTML
+    else:
+        st.session_state["rendered_html"] = render_html_for_spec(initial.spec)
+
+
+# Tiny standalone HTML used when the on-disk YAML is itself invalid.
+_BROKEN_PLACEHOLDER_HTML = """<!DOCTYPE html><html><body style="
+    font-family: ui-monospace, monospace;
+    background:#15181d; color:#e4e6eb; padding:24px; margin:0;">
+<p>No visualization yet — fix the YAML errors to auto-render.</p>
+</body></html>"""
+
+
+# ---------------------------------------------------------------------------
+# UI panels
+# ---------------------------------------------------------------------------
+
+
+def _render_validation_badge(validation: _ValidationResult) -> None:
+    """Show a green tick + summary, or a red cross + the raw exception text."""
+    if validation.is_valid:
+        spec = validation.spec
+        st.success(
+            f"Valid spec — {spec.env_name} · {len(spec.nodes)} nodes · "
+            f"{len(spec.tasks)} tasks · initial state: {spec.initial_state_spec.id}",
+            icon="✅",
+        )
+    else:
+        st.error(f"Invalid YAML\n\n```\n{validation.error}\n```", icon="🛑")
+
+
+def _render_save_button(validation: _ValidationResult) -> None:
+    """Render the Save button. Disabled while the YAML is invalid."""
+    can_save = validation.is_valid
+    save_path_str = st.session_state["save_path"]
+
+    if st.button(
+        f"Save to {Path(save_path_str).name}",
+        disabled=not can_save,
+        use_container_width=True,
+        help=f"Writes the editor contents to {save_path_str}. Disabled while YAML is invalid.",
+    ):
+        try:
+            Path(save_path_str).write_text(st.session_state["edited_text"], encoding="utf-8")
+            # Update "original" so future comparisons are against the saved file.
+            st.session_state["original_text"] = st.session_state["edited_text"]
+            st.toast(f"Saved → {save_path_str}", icon="💾")
+        except OSError as exc:
+            st.error(f"Save failed: {exc}", icon="🛑")
+
+    with st.expander("Change save location", expanded=False):
+        new_path = st.text_input(
+            "Save path",
+            value=save_path_str,
+            key="save_path_input",
+            help="Defaults to the YAML file passed via --yaml.",
+        )
+        if new_path and new_path != save_path_str:
+            st.session_state["save_path"] = new_path
+
+
+def _render_editor_panel(yaml_path: Path) -> _ValidationResult:
+    """Left pane. Returns the validation result for the current editor text.
+
+    Returning the validation result (rather than stashing it in session_state)
+    keeps the data flow inside one render pass and avoids a stale-state class
+    of bug where the badge and the buttons disagree.
+    """
+    # Lazy import so the module is importable from environments that don't
+    # have streamlit-ace installed yet (we surface a clean error message
+    # rather than ImportError at module load).
+    try:
+        from streamlit_ace import st_ace  # noqa: PLC0415
+    except ImportError as exc:
+        # See review_graph._serve_live_editor for why --user --ignore-installed
+        # is required inside the isaaclab_arena container.
+        st.error(
+            "`streamlit-ace` is not installed. Inside the isaaclab_arena container run:\n"
+            "`python -m pip install --user --ignore-installed streamlit-ace`\n\n"
+            f"Underlying error: {exc}",
+            icon="🛑",
+        )
+        st.stop()
+
+    st.subheader("YAML editor")
+    st.caption(f"Source: `{yaml_path}`")
+
+    # ``auto_update=False`` commits on blur / Ctrl+Enter rather than on every
+    # keystroke, showing an "Apply" button in the editor toolbar.
+    new_text = st_ace(
+        value=st.session_state["edited_text"],
+        language="yaml",
+        theme="monokai",
+        keybinding="vscode",
+        font_size=13,
+        tab_size=2,
+        show_gutter=True,
+        show_print_margin=False,
+        wrap=False,
+        auto_update=False,
+        min_lines=30,
+        # Key bound to the YAML path so swapping --yaml between sessions
+        # forces ace to remount with the new content.
+        key=f"ace_editor::{yaml_path}",
+    )
+    if new_text is not None:
+        st.session_state["edited_text"] = new_text
+
+    validation = _validate_yaml_text(st.session_state["edited_text"])
+    _render_validation_badge(validation)
+
+    # Auto-render whenever the YAML is valid and has changed since the last
+    # render. This runs before the right pane is drawn, so the updated HTML
+    # is already in session_state when the iframe is mounted — no extra rerun
+    # needed.
+    edited_since_render = st.session_state["edited_text"] != st.session_state["last_rendered_text"]
+    if validation.is_valid and edited_since_render:
+        with st.spinner("Rendering visualization…"):
+            st.session_state["rendered_html"] = render_html_for_spec(validation.spec)
+        st.session_state["last_rendered_text"] = st.session_state["edited_text"]
+        st.toast("Visualization updated.", icon="🔄")
+
+    _render_save_button(validation)
+    return validation
+
+
+def _render_visualization_panel() -> None:
+    """Right pane — iframe-mount the cached rendered HTML."""
+    st.subheader("Visualization")
+    st.caption("Updates automatically when the YAML is valid.")
+
+    # ``st.components.v1.html`` wraps the payload in a sandboxed iframe, which
+    # is what we want — the mermaid CDN script and the static CSS stay
+    # isolated from Streamlit's own DOM.
+    st.components.v1.html(
+        st.session_state["rendered_html"],
+        height=_IFRAME_HEIGHT_PX,
+        scrolling=True,
+    )
+
+
+# ---------------------------------------------------------------------------
+# Entry point
+# ---------------------------------------------------------------------------
+
+
+def main() -> None:
+    st.set_page_config(
+        page_title="ArenaEnvInitialGraphSpec live editor",
+        layout="wide",
+        initial_sidebar_state="collapsed",
+    )
+
+    args = _parse_args()
+    yaml_path = args.yaml.resolve()
+    if not yaml_path.exists():
+        st.error(f"YAML file not found: {yaml_path}", icon="🛑")
+        st.stop()
+
+    _initialize_state(yaml_path)
+
+    st.markdown("### ArenaEnvInitialGraphSpec live editor")
+    left, right = st.columns([2, 3], gap="large")
+    with left:
+        _render_editor_panel(yaml_path)
+    with right:
+        _render_visualization_panel()
+
+
+# Streamlit invokes the script top-level on every rerun, so we run main()
+# unconditionally. The standard ``if __name__ == "__main__"`` guard would
+# also work under ``streamlit run`` but is unnecessary — this module is only
+# ever loaded as the Streamlit entrypoint.
+main()
diff --git a/isaaclab_arena/agentic_environment_generation/review_graph.py b/isaaclab_arena/agentic_environment_generation/review_graph.py
new file mode 100644
index 000000000..0bf2ecbda
--- /dev/null
+++ b/isaaclab_arena/agentic_environment_generation/review_graph.py
@@ -0,0 +1,444 @@
+# Copyright (c) 2025-2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""ArenaEnvInitialGraphSpec review tool — Streamlit live editor.
+
+The CLI is a thin launcher: it boots the Streamlit app in ``review_app.py``.
+
+The tool accepts an ``ArenaEnvInitialGraphSpec`` YAML as input. The user
+edits the spec directly inside the Streamlit editor and the preview updates
+in real time.
+
+Three panels (dark dashboard style) inside the embedded view:
+  * Top-left — graph diagram (mermaid.js, CDN-loaded) of the initial-state
+    spatial constraints. Anchor nodes are highlighted; constraints without
+    a reference (is_anchor / position_limits / at_pose / ...) are listed below
+    the graph rather than rendered as self-loops.
+  * Bottom-left — task table (index, kind, description, params).
+  * Right — node card grid: type badge, asset name, and the per-node YAML
+    stanza.
+
+Usage:
+    /isaac-sim/python.sh -m isaaclab_arena.agentic_environment_generation.review_graph \\
+        --yaml isaaclab_arena/tests/test_data/pick_and_place_maple_table_init_env_graph.yaml
+
+    # Custom port:
+    /isaac-sim/python.sh -m isaaclab_arena.agentic_environment_generation.review_graph \\
+        --yaml <path> --port 8600
+
+Public API used by ``review_app.py``:
+    * :func:`render_html_for_spec` — full HTML payload for a spec.
+"""
+
+from __future__ import annotations
+
+import argparse
+import html as html_lib
+import os
+import re
+import subprocess
+import sys
+import yaml
+from pathlib import Path
+
+from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
+from isaaclab_arena.environments.arena_env_graph_types import ArenaEnvGraphNodeSpec, ArenaEnvGraphStateSpec
+
+
+def main() -> None:
+    """CLI entry point — argparse parses the user's flags, then we hand off
+    to Streamlit. The actual interactive UI lives in ``review_app.py``.
+    """
+    parser = argparse.ArgumentParser(
+        description=__doc__,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    parser.add_argument(
+        "--yaml",
+        type=Path,
+        required=True,
+        help="Path to an ArenaEnvInitialGraphSpec YAML file. The Streamlit app will open it for live editing.",
+    )
+    parser.add_argument(
+        "--port",
+        type=int,
+        default=8501,
+        help="Streamlit server port (default: 8501).",
+    )
+    args = parser.parse_args()
+    _serve_live_editor(args.yaml, port=args.port)
+
+
+def _serve_live_editor(yaml_path: Path, port: int = 8501) -> None:
+    """Spawn ``streamlit run review_app.py -- --yaml <path>`` and wait.
+
+    We resolve ``review_app.py`` next to this file rather than going through
+    ``-m`` so Streamlit picks the path up cleanly (``streamlit run`` doesn't
+    accept module dotted-paths).
+    """
+    app_path = Path(__file__).with_name("review_app.py")
+    if not app_path.exists():
+        raise FileNotFoundError(f"Streamlit app not found at {app_path} — installation is incomplete.")
+
+    cmd = [
+        sys.executable,
+        "-m",
+        "streamlit",
+        "run",
+        str(app_path),
+        "--server.port",
+        str(port),
+        # Skip the email prompt the first time Streamlit runs in a fresh
+        # container — the live editor is a developer tool, not a hosted
+        # service, and an interactive prompt would block automation.
+        "--browser.gatherUsageStats",
+        "false",
+        # File watcher is a footgun here: Kit's ``SimulationApp`` boot is
+        # tens of seconds; we don't want Streamlit silently rerunning the
+        # script (and reissuing the cached_resource init) every time we
+        # save a source file during development. The user can still hit "R"
+        # in the browser to force a rerun if they want.
+        "--server.fileWatcherType",
+        "none",
+        "--",
+        "--yaml",
+        str(yaml_path.resolve()),
+    ]
+
+    # Inherit env so the Streamlit subprocess sees PYTHONPATH / isaac-sim
+    # site-packages exactly the same way we do.
+    print(f"[review_graph] launching Streamlit live editor: {' '.join(cmd)}", file=sys.stderr)
+    try:
+        subprocess.run(cmd, env=os.environ.copy(), check=True)
+    except FileNotFoundError as exc:
+        # The plain ``pip install streamlit`` fails inside the isaaclab_arena
+        # container because streamlit≥1.30 needs uvicorn>=0.30 but Kit ships
+        # a bundled uvicorn==0.29 under a read-only /isaac-sim/extscache path.
+        # ``--user --ignore-installed`` sidesteps the rollback by writing
+        # everything to ~/.local (which is earlier on sys.path than extscache).
+        raise SystemExit(
+            "Streamlit is not installed. Inside the isaaclab_arena container run:\n"
+            "  python -m pip install --user --ignore-installed streamlit streamlit-ace"
+        ) from exc
+    except KeyboardInterrupt:
+        # Normal exit path — user hit Ctrl-C in the terminal.
+        pass
+
+
+# ---------------------------------------------------------------------------
+# Public API consumed by review_app.py
+# ---------------------------------------------------------------------------
+
+
+def render_html_for_spec(spec: ArenaEnvInitialGraphSpec) -> str:
+    """Render the review HTML for ``spec`` with placeholder node thumbnails.
+
+    Thin public alias of :func:`_render_html` so external entry points don't
+    have to reach into a private name.
+    """
+    return _render_html(spec)
+
+
+# ---------------------------------------------------------------------------
+# Top-level HTML
+# ---------------------------------------------------------------------------
+
+
+def _render_html(spec: ArenaEnvInitialGraphSpec) -> str:
+    initial_state = spec.initial_state_spec
+    return f"""<!DOCTYPE html>
+<html lang="en">
+<head>
+<meta charset="utf-8">
+<title>{html_lib.escape(spec.env_name)} — graph review</title>
+<script src="https://cdn.jsdelivr.net/npm/mermaid@10/dist/mermaid.min.js"></script>
+<style>{_CSS}</style>
+</head>
+<body>
+<header>
+  <h1>{html_lib.escape(spec.env_name)}</h1>
+  <p class="sub">{len(spec.nodes)} nodes · {len(spec.tasks)} tasks · initial state: <code>{html_lib.escape(initial_state.id)}</code></p>
+</header>
+<main>
+  <section class="panel graph-panel">
+    <h2>Spatial graph <span class="muted">(initial state: <code>{html_lib.escape(initial_state.id)}</code>)</span></h2>
+    <pre class="mermaid">{_render_mermaid(spec, initial_state)}</pre>
+    {_render_unary_constraints(initial_state)}
+  </section>
+  <section class="panel tasks-panel">
+    <h2>Tasks</h2>
+    {_render_tasks_table(spec)}
+  </section>
+  <section class="panel nodes-panel">
+    <h2>Nodes</h2>
+    <div class="node-grid">{_render_node_cards(spec)}</div>
+  </section>
+</main>
+<script>mermaid.initialize({{ startOnLoad: true, theme: 'dark', themeVariables: {{ fontFamily: 'ui-monospace, monospace' }} }});</script>
+</body>
+</html>
+"""
+
+
+# ---------------------------------------------------------------------------
+# Mermaid graph rendering
+# ---------------------------------------------------------------------------
+
+
+def _render_mermaid(spec: ArenaEnvInitialGraphSpec, state: ArenaEnvGraphStateSpec) -> str:
+    """Emit a left-to-right mermaid graph of spatial and task constraints.
+
+    Binary spatial constraints (reference is set) are drawn as solid edges:
+        subject -->|kind| reference
+
+    Unary spatial constraints (no reference) are omitted from the graph and
+    listed below it by :func:`_render_unary_constraints` so their params are
+    visible.
+
+    Task constraints with a child are drawn as dashed edges:
+        parent -.->|type| child
+
+    object_reference nodes are drawn with a dotted edge to their parent node:
+        ref_node -. ref .-> parent_node
+    """
+    lines = ["graph LR"]
+
+    anchor_ids: set[str] = set()
+    edge_nodes: set[str] = set()
+
+    # --- Spatial constraints (binary only) ---
+    for c in state.spatial_constraints:
+        kind = c.kind
+        if kind == "is_anchor":
+            anchor_ids.add(c.subject)
+        if c.reference is not None:
+            lines.append(
+                f"  {_mermaid_id(c.subject)}[{_mermaid_label(c.subject)}]"
+                f" -->|{kind}| "
+                f"{_mermaid_id(c.reference)}[{_mermaid_label(c.reference)}]"
+            )
+            edge_nodes.add(c.subject)
+            edge_nodes.add(c.reference)
+
+    # --- Task constraints (dashed edges, binary only) ---
+    for tc in state.task_constraints:
+        if tc.child is not None:
+            lines.append(
+                f"  {_mermaid_id(tc.parent)}[{_mermaid_label(tc.parent)}]"
+                f" -.->|{_mermaid_label(tc.type.value)}| "
+                f"{_mermaid_id(tc.child)}[{_mermaid_label(tc.child)}]"
+            )
+            edge_nodes.add(tc.parent)
+            edge_nodes.add(tc.child)
+
+    # Include every node from the spec so disconnected ones still appear.
+    for node in spec.nodes:
+        if node.id not in edge_nodes:
+            lines.append(f"  {_mermaid_id(node.id)}[{_mermaid_label(node.id)}]")
+
+    # --- object_reference → parent edges (dotted, structural) ---
+    # Use bare node IDs (no label re-declaration) — all nodes are already
+    # declared above either in constraint edges or in the disconnected-node block.
+    nodes_by_id = spec.nodes_by_id
+    for node in spec.nodes:
+        if node.type.value == "object_reference" and node.parent is not None:
+            if node.parent in nodes_by_id:
+                lines.append(f"  {_mermaid_id(node.id)} -.->|ref| {_mermaid_id(node.parent)}")
+
+    # Anchor highlight.
+    for anchor_id in anchor_ids:
+        lines.append(f"  style {_mermaid_id(anchor_id)} fill:#3a7d44,color:#fff,stroke:#7fd17f,stroke-width:2px")
+
+    # Color nodes by type for quick visual scanning.
+    type_palette = {
+        "background": ("#3a4f7a", "#7aa0d8"),
+        "embodiment": ("#7a3a3a", "#d87a7a"),
+        "object": ("#7a6b3a", "#d8c47a"),
+        "object_reference": ("#6b3a7a", "#c47ad8"),
+        "lighting": ("#3a7a7a", "#7ad8d8"),
+    }
+    for node in spec.nodes:
+        if node.id in anchor_ids:
+            continue  # anchor style wins
+        fill, stroke = type_palette.get(node.type.value, ("#3a3d44", "#888"))
+        lines.append(f"  style {_mermaid_id(node.id)} fill:{fill},color:#fff,stroke:{stroke}")
+
+    return "\n".join(lines)
+
+
+_MERMAID_ID_SAFE = re.compile(r"[^A-Za-z0-9_]")
+
+
+def _mermaid_id(s: str) -> str:
+    """Mermaid node identifiers must be alphanumeric / underscore."""
+    return _MERMAID_ID_SAFE.sub("_", s)
+
+
+def _mermaid_label(s: str) -> str:
+    """Escape mermaid-significant characters inside node labels."""
+    return s.replace('"', "&quot;").replace("|", "&#124;")
+
+
+def _render_unary_constraints(state: ArenaEnvGraphStateSpec) -> str:
+    """List constraints without a reference below the graph (anchors, position_limits, ...)."""
+    rows = []
+    for c in state.spatial_constraints:
+        if c.reference is not None:
+            continue
+        params = (
+            f' <code class="muted">{html_lib.escape(yaml.safe_dump(c.params, default_flow_style=True).rstrip())}</code>'
+            if c.params
+            else ""
+        )
+        rows.append(
+            f'<li><span class="badge type-{html_lib.escape(c.kind)}">{html_lib.escape(c.kind)}</span>'
+            f" on <code>{html_lib.escape(c.subject)}</code>{params}</li>"
+        )
+    if not rows:
+        return ""
+    return (
+        f'<details open class="unary"><summary>Unary constraints ({len(rows)})</summary>'
+        f'<ul>{"".join(rows)}</ul></details>'
+    )
+
+
+# ---------------------------------------------------------------------------
+# Tasks panel
+# ---------------------------------------------------------------------------
+
+
+def _render_tasks_table(spec: ArenaEnvInitialGraphSpec) -> str:
+    if not spec.tasks:
+        return "<p class='muted'><em>No tasks defined.</em></p>"
+    rows = []
+    for i, t in enumerate(spec.tasks):
+        params_str = yaml.safe_dump(t.params, sort_keys=False).rstrip() if t.params else "(empty)"
+        desc = html_lib.escape(t.description or "")
+        rows.append(
+            "<tr>"
+            f"<td><code>{i}</code></td>"
+            f'<td><span class="badge type-task">{html_lib.escape(t.kind)}</span></td>'
+            f"<td>{desc}</td>"
+            f"<td><pre>{html_lib.escape(params_str)}</pre></td>"
+            "</tr>"
+        )
+    return (
+        "<table class='tasks'>"
+        "<thead><tr><th>#</th><th>kind</th><th>description</th><th>params</th></tr></thead>"
+        f"<tbody>{''.join(rows)}</tbody>"
+        "</table>"
+    )
+
+
+# ---------------------------------------------------------------------------
+# Node cards
+# ---------------------------------------------------------------------------
+
+
+def _render_node_cards(spec: ArenaEnvInitialGraphSpec) -> str:
+    return "\n".join(_render_one_node_card(node) for node in spec.nodes)
+
+
+def _render_one_node_card(node: ArenaEnvGraphNodeSpec) -> str:
+    node_dict = node.model_dump(mode="json", exclude_none=True)
+    node_yaml = yaml.safe_dump(node_dict, sort_keys=False).rstrip()
+    thumb = _render_node_thumbnail(node)
+    return f"""<article class="node-card type-{html_lib.escape(node.type.value)}">
+  {thumb}
+  <div class="node-meta">
+    <div class="node-id">{html_lib.escape(node.id)}</div>
+    <span class="badge type-{html_lib.escape(node.type.value)}">{html_lib.escape(node.type.value)}</span>
+  </div>
+  <pre class="node-yaml">{html_lib.escape(node_yaml)}</pre>
+</article>"""
+
+
+def _render_node_thumbnail(node: ArenaEnvGraphNodeSpec) -> str:
+    """Per-node placeholder thumbnail — two-letter initial."""
+    initial = (node.name[:2] if node.name else "?").upper()
+    return f"""<div class="thumb">
+    <span class="thumb-initial">{html_lib.escape(initial)}</span>
+    <span class="thumb-name">{html_lib.escape(node.name)}</span>
+  </div>"""
+
+
+# ---------------------------------------------------------------------------
+# Styling
+# ---------------------------------------------------------------------------
+
+_CSS = """
+:root {
+  --bg: #15181d;
+  --bg-elev: #1d2128;
+  --bg-elev2: #262b34;
+  --border: #2f343d;
+  --fg: #e4e6eb;
+  --fg-muted: #8a9099;
+  --accent: #7fd17f;
+}
+* { box-sizing: border-box; }
+body { margin: 0; padding: 24px; font: 14px/1.5 -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
+       background: var(--bg); color: var(--fg); }
+header { margin-bottom: 16px; }
+header h1 { margin: 0; font-size: 28px; font-weight: 700; }
+header .sub { margin: 4px 0 0; color: var(--fg-muted); font-size: 13px; }
+main { display: grid; grid-template-columns: 1fr 1fr; grid-template-rows: auto auto;
+       grid-template-areas: "graph nodes" "tasks nodes"; gap: 16px; }
+.graph-panel { grid-area: graph; }
+.tasks-panel { grid-area: tasks; }
+.nodes-panel { grid-area: nodes; }
+.panel { background: var(--bg-elev); border: 1px solid var(--border); border-radius: 8px; padding: 16px; }
+.panel h2 { margin: 0 0 12px; font-size: 16px; font-weight: 600; letter-spacing: 0.02em; }
+.panel h2 .muted { color: var(--fg-muted); font-weight: 400; font-size: 13px; }
+code { font-family: ui-monospace, 'SF Mono', Menlo, monospace; font-size: 12px;
+       background: var(--bg-elev2); padding: 1px 6px; border-radius: 4px; }
+pre { font-family: ui-monospace, 'SF Mono', Menlo, monospace; font-size: 12px;
+      background: var(--bg-elev2); padding: 10px 12px; border-radius: 6px; margin: 0;
+      white-space: pre-wrap; word-break: break-word; }
+.muted { color: var(--fg-muted); }
+.badge { display: inline-block; padding: 2px 8px; border-radius: 999px; font-size: 11px;
+         font-weight: 600; letter-spacing: 0.03em; background: var(--bg-elev2); color: var(--fg); }
+.badge.type-background { background: #3a4f7a; }
+.badge.type-embodiment { background: #7a3a3a; }
+.badge.type-object { background: #7a6b3a; }
+.badge.type-object_reference { background: #6b3a7a; }
+.badge.type-lighting { background: #3a7a7a; }
+.badge.type-is_anchor { background: #3a7d44; }
+.badge.type-position_limits, .badge.type-at_pose, .badge.type-at_position { background: #6b3a7a; }
+.badge.type-task { background: #2f343d; border: 1px solid #4a5; color: var(--accent); }
+.mermaid { background: var(--bg-elev2); padding: 8px; border-radius: 6px; min-height: 220px;
+           display: flex; align-items: center; justify-content: center; }
+.unary { margin-top: 12px; }
+.unary summary { cursor: pointer; color: var(--fg-muted); font-size: 13px; padding: 4px 0; }
+.unary ul { margin: 8px 0 0; padding-left: 20px; list-style: disc; color: var(--fg); }
+.unary li { padding: 3px 0; }
+table.tasks { width: 100%; border-collapse: collapse; }
+table.tasks th, table.tasks td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border);
+                                  vertical-align: top; font-size: 12px; }
+table.tasks th { color: var(--fg-muted); font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em; }
+table.tasks pre { padding: 6px 8px; font-size: 11px; }
+.node-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 12px; }
+.node-card { background: var(--bg-elev2); border: 1px solid var(--border); border-radius: 8px;
+             padding: 12px; display: flex; flex-direction: column; gap: 10px; }
+.node-card .thumb { aspect-ratio: 1 / 1; background: linear-gradient(135deg, #2a2f37, #1c2026);
+                    border-radius: 6px; display: flex; flex-direction: column;
+                    align-items: center; justify-content: center; color: var(--fg-muted);
+                    position: relative; overflow: hidden; }
+.node-card .thumb-rendered { background: #0e1115; }
+.node-card .thumb-rendered img { width: 100%; height: 100%; object-fit: contain; display: block; }
+.node-card .thumb-rendered .thumb-name { position: absolute; bottom: 0; left: 0; right: 0;
+                                         padding: 4px 6px; background: rgba(15, 17, 21, 0.78);
+                                         color: var(--fg); margin: 0; }
+.thumb-initial { font-size: 36px; font-weight: 700; color: var(--fg); opacity: 0.6;
+                 font-family: ui-monospace, monospace; }
+.thumb-name { font-size: 10px; margin-top: 6px; padding: 0 8px; text-align: center; word-break: break-word; }
+.node-meta { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
+.node-id { font-family: ui-monospace, monospace; font-size: 13px; font-weight: 600; word-break: break-all; }
+.node-yaml { font-size: 11px; }
+"""
+
+
+if __name__ == "__main__":
+    main()
diff --git a/isaaclab_arena/environments/arena_env_graph_spec.py b/isaaclab_arena/environments/arena_env_graph_spec.py
index 0dc3d6db6..c11c09656 100644
--- a/isaaclab_arena/environments/arena_env_graph_spec.py
+++ b/isaaclab_arena/environments/arena_env_graph_spec.py
@@ -83,6 +83,18 @@ def write_yaml(self, path: str | Path) -> None:
         with Path(path).open("w", encoding="utf-8") as f:
             yaml.safe_dump(self.to_dict(), f, sort_keys=False)
 
+    def to_yaml(self, path: str | Path) -> Path:
+        """Write this spec to ``path`` as YAML. Creates parent dirs as needed.
+
+        Returns the resolved :class:`Path` written. Symmetric with
+        :meth:`from_yaml`.
+        """
+        out_path = Path(path)
+        out_path.parent.mkdir(parents=True, exist_ok=True)
+        with out_path.open("w", encoding="utf-8") as f:
+            yaml.safe_dump(self.to_dict(), f, sort_keys=False)
+        return out_path
+
     @property
     def nodes_by_id(self) -> dict[str, ArenaEnvGraphNodeSpec]:
         return {node.id: node for node in self.nodes}
diff --git a/setup.py b/setup.py
index 582f669ec..4f86c948b 100644
--- a/setup.py
+++ b/setup.py
@@ -28,6 +28,11 @@
     "tenacity",
 ]
 
+ENV_REVIEW_DEPS = [
+    "streamlit>=1.30",
+    "streamlit-ace>=0.1.1",
+]
+
 setup(
     name="isaaclab_arena",
     version=ISAACLAB_ARENA_VERSION_NUMBER,
@@ -46,6 +51,7 @@
     install_requires=RUNTIME_DEPS,
     extras_require={
         "dev": DEV_DEPS,
+        "env-review": ENV_REVIEW_DEPS,
     },
     zip_safe=False,
 )

From 080749130dc5e8093db56c80da19d99571449fd8 Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Mon, 15 Jun 2026 01:34:43 -0700
Subject: [PATCH 02/19] fix copyright years

---
 isaaclab_arena/agentic_environment_generation/review_app.py   | 2 +-
 isaaclab_arena/agentic_environment_generation/review_graph.py | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/isaaclab_arena/agentic_environment_generation/review_app.py b/isaaclab_arena/agentic_environment_generation/review_app.py
index 1a156190a..1e51132d7 100644
--- a/isaaclab_arena/agentic_environment_generation/review_app.py
+++ b/isaaclab_arena/agentic_environment_generation/review_app.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2025-2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
 # All rights reserved.
 #
 # SPDX-License-Identifier: Apache-2.0
diff --git a/isaaclab_arena/agentic_environment_generation/review_graph.py b/isaaclab_arena/agentic_environment_generation/review_graph.py
index 0bf2ecbda..edee396ac 100644
--- a/isaaclab_arena/agentic_environment_generation/review_graph.py
+++ b/isaaclab_arena/agentic_environment_generation/review_graph.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2025-2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
 # All rights reserved.
 #
 # SPDX-License-Identifier: Apache-2.0

From 07c9d7f737f5431c5ef504fa5e50d8fabeaebff8 Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Mon, 15 Jun 2026 01:35:22 -0700
Subject: [PATCH 03/19] Move folder

---
 .../agentic_environment_generation/review_app.py                  | 0
 .../agentic_environment_generation/review_graph.py                | 0
 2 files changed, 0 insertions(+), 0 deletions(-)
 rename {isaaclab_arena => isaaclab_arena_examples}/agentic_environment_generation/review_app.py (100%)
 rename {isaaclab_arena => isaaclab_arena_examples}/agentic_environment_generation/review_graph.py (100%)

diff --git a/isaaclab_arena/agentic_environment_generation/review_app.py b/isaaclab_arena_examples/agentic_environment_generation/review_app.py
similarity index 100%
rename from isaaclab_arena/agentic_environment_generation/review_app.py
rename to isaaclab_arena_examples/agentic_environment_generation/review_app.py
diff --git a/isaaclab_arena/agentic_environment_generation/review_graph.py b/isaaclab_arena_examples/agentic_environment_generation/review_graph.py
similarity index 100%
rename from isaaclab_arena/agentic_environment_generation/review_graph.py
rename to isaaclab_arena_examples/agentic_environment_generation/review_graph.py

From f84bb1c3882c16a0b3b639f15c7a58c9c19437db Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Mon, 15 Jun 2026 01:37:28 -0700
Subject: [PATCH 04/19] Simplify setup

---
 setup.py | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/setup.py b/setup.py
index 4f86c948b..c411f629b 100644
--- a/setup.py
+++ b/setup.py
@@ -26,9 +26,6 @@
     "jupyter",
     "debugpy",
     "tenacity",
-]
-
-ENV_REVIEW_DEPS = [
     "streamlit>=1.30",
     "streamlit-ace>=0.1.1",
 ]
@@ -51,7 +48,6 @@
     install_requires=RUNTIME_DEPS,
     extras_require={
         "dev": DEV_DEPS,
-        "env-review": ENV_REVIEW_DEPS,
     },
     zip_safe=False,
 )

From 19ab3dfd6cb28cbab106d59233e5e6f8ec3c0dcf Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Mon, 15 Jun 2026 02:32:54 -0700
Subject: [PATCH 05/19] Refactor graph review tool into review_gui package.

Replace monolithic review_graph.py and review_app.py with server, streamlit_ui,
and a render subpackage; node thumbnails remain placeholders until SimApp lands.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../review_graph.py                           | 444 ------------------
 .../review_gui/__init__.py                    |   6 +
 .../review_gui/render/__init__.py             |   6 +
 .../review_gui/render/html_document.py        |  54 +++
 .../review_gui/render/mermaid_graph.py        |  96 ++++
 .../review_gui/render/panels.py               |  80 ++++
 .../review_gui/render/styles.py               |  75 +++
 .../review_gui/render/thumbnails.py           |  20 +
 .../review_gui/server.py                      |  85 ++++
 .../streamlit_ui.py}                          | 151 ++----
 10 files changed, 466 insertions(+), 551 deletions(-)
 delete mode 100644 isaaclab_arena_examples/agentic_environment_generation/review_graph.py
 create mode 100644 isaaclab_arena_examples/agentic_environment_generation/review_gui/__init__.py
 create mode 100644 isaaclab_arena_examples/agentic_environment_generation/review_gui/render/__init__.py
 create mode 100644 isaaclab_arena_examples/agentic_environment_generation/review_gui/render/html_document.py
 create mode 100644 isaaclab_arena_examples/agentic_environment_generation/review_gui/render/mermaid_graph.py
 create mode 100644 isaaclab_arena_examples/agentic_environment_generation/review_gui/render/panels.py
 create mode 100644 isaaclab_arena_examples/agentic_environment_generation/review_gui/render/styles.py
 create mode 100644 isaaclab_arena_examples/agentic_environment_generation/review_gui/render/thumbnails.py
 create mode 100644 isaaclab_arena_examples/agentic_environment_generation/review_gui/server.py
 rename isaaclab_arena_examples/agentic_environment_generation/{review_app.py => review_gui/streamlit_ui.py} (53%)

diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_graph.py b/isaaclab_arena_examples/agentic_environment_generation/review_graph.py
deleted file mode 100644
index edee396ac..000000000
--- a/isaaclab_arena_examples/agentic_environment_generation/review_graph.py
+++ /dev/null
@@ -1,444 +0,0 @@
-# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
-# All rights reserved.
-#
-# SPDX-License-Identifier: Apache-2.0
-
-"""ArenaEnvInitialGraphSpec review tool — Streamlit live editor.
-
-The CLI is a thin launcher: it boots the Streamlit app in ``review_app.py``.
-
-The tool accepts an ``ArenaEnvInitialGraphSpec`` YAML as input. The user
-edits the spec directly inside the Streamlit editor and the preview updates
-in real time.
-
-Three panels (dark dashboard style) inside the embedded view:
-  * Top-left — graph diagram (mermaid.js, CDN-loaded) of the initial-state
-    spatial constraints. Anchor nodes are highlighted; constraints without
-    a reference (is_anchor / position_limits / at_pose / ...) are listed below
-    the graph rather than rendered as self-loops.
-  * Bottom-left — task table (index, kind, description, params).
-  * Right — node card grid: type badge, asset name, and the per-node YAML
-    stanza.
-
-Usage:
-    /isaac-sim/python.sh -m isaaclab_arena.agentic_environment_generation.review_graph \\
-        --yaml isaaclab_arena/tests/test_data/pick_and_place_maple_table_init_env_graph.yaml
-
-    # Custom port:
-    /isaac-sim/python.sh -m isaaclab_arena.agentic_environment_generation.review_graph \\
-        --yaml <path> --port 8600
-
-Public API used by ``review_app.py``:
-    * :func:`render_html_for_spec` — full HTML payload for a spec.
-"""
-
-from __future__ import annotations
-
-import argparse
-import html as html_lib
-import os
-import re
-import subprocess
-import sys
-import yaml
-from pathlib import Path
-
-from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
-from isaaclab_arena.environments.arena_env_graph_types import ArenaEnvGraphNodeSpec, ArenaEnvGraphStateSpec
-
-
-def main() -> None:
-    """CLI entry point — argparse parses the user's flags, then we hand off
-    to Streamlit. The actual interactive UI lives in ``review_app.py``.
-    """
-    parser = argparse.ArgumentParser(
-        description=__doc__,
-        formatter_class=argparse.RawDescriptionHelpFormatter,
-    )
-    parser.add_argument(
-        "--yaml",
-        type=Path,
-        required=True,
-        help="Path to an ArenaEnvInitialGraphSpec YAML file. The Streamlit app will open it for live editing.",
-    )
-    parser.add_argument(
-        "--port",
-        type=int,
-        default=8501,
-        help="Streamlit server port (default: 8501).",
-    )
-    args = parser.parse_args()
-    _serve_live_editor(args.yaml, port=args.port)
-
-
-def _serve_live_editor(yaml_path: Path, port: int = 8501) -> None:
-    """Spawn ``streamlit run review_app.py -- --yaml <path>`` and wait.
-
-    We resolve ``review_app.py`` next to this file rather than going through
-    ``-m`` so Streamlit picks the path up cleanly (``streamlit run`` doesn't
-    accept module dotted-paths).
-    """
-    app_path = Path(__file__).with_name("review_app.py")
-    if not app_path.exists():
-        raise FileNotFoundError(f"Streamlit app not found at {app_path} — installation is incomplete.")
-
-    cmd = [
-        sys.executable,
-        "-m",
-        "streamlit",
-        "run",
-        str(app_path),
-        "--server.port",
-        str(port),
-        # Skip the email prompt the first time Streamlit runs in a fresh
-        # container — the live editor is a developer tool, not a hosted
-        # service, and an interactive prompt would block automation.
-        "--browser.gatherUsageStats",
-        "false",
-        # File watcher is a footgun here: Kit's ``SimulationApp`` boot is
-        # tens of seconds; we don't want Streamlit silently rerunning the
-        # script (and reissuing the cached_resource init) every time we
-        # save a source file during development. The user can still hit "R"
-        # in the browser to force a rerun if they want.
-        "--server.fileWatcherType",
-        "none",
-        "--",
-        "--yaml",
-        str(yaml_path.resolve()),
-    ]
-
-    # Inherit env so the Streamlit subprocess sees PYTHONPATH / isaac-sim
-    # site-packages exactly the same way we do.
-    print(f"[review_graph] launching Streamlit live editor: {' '.join(cmd)}", file=sys.stderr)
-    try:
-        subprocess.run(cmd, env=os.environ.copy(), check=True)
-    except FileNotFoundError as exc:
-        # The plain ``pip install streamlit`` fails inside the isaaclab_arena
-        # container because streamlit≥1.30 needs uvicorn>=0.30 but Kit ships
-        # a bundled uvicorn==0.29 under a read-only /isaac-sim/extscache path.
-        # ``--user --ignore-installed`` sidesteps the rollback by writing
-        # everything to ~/.local (which is earlier on sys.path than extscache).
-        raise SystemExit(
-            "Streamlit is not installed. Inside the isaaclab_arena container run:\n"
-            "  python -m pip install --user --ignore-installed streamlit streamlit-ace"
-        ) from exc
-    except KeyboardInterrupt:
-        # Normal exit path — user hit Ctrl-C in the terminal.
-        pass
-
-
-# ---------------------------------------------------------------------------
-# Public API consumed by review_app.py
-# ---------------------------------------------------------------------------
-
-
-def render_html_for_spec(spec: ArenaEnvInitialGraphSpec) -> str:
-    """Render the review HTML for ``spec`` with placeholder node thumbnails.
-
-    Thin public alias of :func:`_render_html` so external entry points don't
-    have to reach into a private name.
-    """
-    return _render_html(spec)
-
-
-# ---------------------------------------------------------------------------
-# Top-level HTML
-# ---------------------------------------------------------------------------
-
-
-def _render_html(spec: ArenaEnvInitialGraphSpec) -> str:
-    initial_state = spec.initial_state_spec
-    return f"""<!DOCTYPE html>
-<html lang="en">
-<head>
-<meta charset="utf-8">
-<title>{html_lib.escape(spec.env_name)} — graph review</title>
-<script src="https://cdn.jsdelivr.net/npm/mermaid@10/dist/mermaid.min.js"></script>
-<style>{_CSS}</style>
-</head>
-<body>
-<header>
-  <h1>{html_lib.escape(spec.env_name)}</h1>
-  <p class="sub">{len(spec.nodes)} nodes · {len(spec.tasks)} tasks · initial state: <code>{html_lib.escape(initial_state.id)}</code></p>
-</header>
-<main>
-  <section class="panel graph-panel">
-    <h2>Spatial graph <span class="muted">(initial state: <code>{html_lib.escape(initial_state.id)}</code>)</span></h2>
-    <pre class="mermaid">{_render_mermaid(spec, initial_state)}</pre>
-    {_render_unary_constraints(initial_state)}
-  </section>
-  <section class="panel tasks-panel">
-    <h2>Tasks</h2>
-    {_render_tasks_table(spec)}
-  </section>
-  <section class="panel nodes-panel">
-    <h2>Nodes</h2>
-    <div class="node-grid">{_render_node_cards(spec)}</div>
-  </section>
-</main>
-<script>mermaid.initialize({{ startOnLoad: true, theme: 'dark', themeVariables: {{ fontFamily: 'ui-monospace, monospace' }} }});</script>
-</body>
-</html>
-"""
-
-
-# ---------------------------------------------------------------------------
-# Mermaid graph rendering
-# ---------------------------------------------------------------------------
-
-
-def _render_mermaid(spec: ArenaEnvInitialGraphSpec, state: ArenaEnvGraphStateSpec) -> str:
-    """Emit a left-to-right mermaid graph of spatial and task constraints.
-
-    Binary spatial constraints (reference is set) are drawn as solid edges:
-        subject -->|kind| reference
-
-    Unary spatial constraints (no reference) are omitted from the graph and
-    listed below it by :func:`_render_unary_constraints` so their params are
-    visible.
-
-    Task constraints with a child are drawn as dashed edges:
-        parent -.->|type| child
-
-    object_reference nodes are drawn with a dotted edge to their parent node:
-        ref_node -. ref .-> parent_node
-    """
-    lines = ["graph LR"]
-
-    anchor_ids: set[str] = set()
-    edge_nodes: set[str] = set()
-
-    # --- Spatial constraints (binary only) ---
-    for c in state.spatial_constraints:
-        kind = c.kind
-        if kind == "is_anchor":
-            anchor_ids.add(c.subject)
-        if c.reference is not None:
-            lines.append(
-                f"  {_mermaid_id(c.subject)}[{_mermaid_label(c.subject)}]"
-                f" -->|{kind}| "
-                f"{_mermaid_id(c.reference)}[{_mermaid_label(c.reference)}]"
-            )
-            edge_nodes.add(c.subject)
-            edge_nodes.add(c.reference)
-
-    # --- Task constraints (dashed edges, binary only) ---
-    for tc in state.task_constraints:
-        if tc.child is not None:
-            lines.append(
-                f"  {_mermaid_id(tc.parent)}[{_mermaid_label(tc.parent)}]"
-                f" -.->|{_mermaid_label(tc.type.value)}| "
-                f"{_mermaid_id(tc.child)}[{_mermaid_label(tc.child)}]"
-            )
-            edge_nodes.add(tc.parent)
-            edge_nodes.add(tc.child)
-
-    # Include every node from the spec so disconnected ones still appear.
-    for node in spec.nodes:
-        if node.id not in edge_nodes:
-            lines.append(f"  {_mermaid_id(node.id)}[{_mermaid_label(node.id)}]")
-
-    # --- object_reference → parent edges (dotted, structural) ---
-    # Use bare node IDs (no label re-declaration) — all nodes are already
-    # declared above either in constraint edges or in the disconnected-node block.
-    nodes_by_id = spec.nodes_by_id
-    for node in spec.nodes:
-        if node.type.value == "object_reference" and node.parent is not None:
-            if node.parent in nodes_by_id:
-                lines.append(f"  {_mermaid_id(node.id)} -.->|ref| {_mermaid_id(node.parent)}")
-
-    # Anchor highlight.
-    for anchor_id in anchor_ids:
-        lines.append(f"  style {_mermaid_id(anchor_id)} fill:#3a7d44,color:#fff,stroke:#7fd17f,stroke-width:2px")
-
-    # Color nodes by type for quick visual scanning.
-    type_palette = {
-        "background": ("#3a4f7a", "#7aa0d8"),
-        "embodiment": ("#7a3a3a", "#d87a7a"),
-        "object": ("#7a6b3a", "#d8c47a"),
-        "object_reference": ("#6b3a7a", "#c47ad8"),
-        "lighting": ("#3a7a7a", "#7ad8d8"),
-    }
-    for node in spec.nodes:
-        if node.id in anchor_ids:
-            continue  # anchor style wins
-        fill, stroke = type_palette.get(node.type.value, ("#3a3d44", "#888"))
-        lines.append(f"  style {_mermaid_id(node.id)} fill:{fill},color:#fff,stroke:{stroke}")
-
-    return "\n".join(lines)
-
-
-_MERMAID_ID_SAFE = re.compile(r"[^A-Za-z0-9_]")
-
-
-def _mermaid_id(s: str) -> str:
-    """Mermaid node identifiers must be alphanumeric / underscore."""
-    return _MERMAID_ID_SAFE.sub("_", s)
-
-
-def _mermaid_label(s: str) -> str:
-    """Escape mermaid-significant characters inside node labels."""
-    return s.replace('"', "&quot;").replace("|", "&#124;")
-
-
-def _render_unary_constraints(state: ArenaEnvGraphStateSpec) -> str:
-    """List constraints without a reference below the graph (anchors, position_limits, ...)."""
-    rows = []
-    for c in state.spatial_constraints:
-        if c.reference is not None:
-            continue
-        params = (
-            f' <code class="muted">{html_lib.escape(yaml.safe_dump(c.params, default_flow_style=True).rstrip())}</code>'
-            if c.params
-            else ""
-        )
-        rows.append(
-            f'<li><span class="badge type-{html_lib.escape(c.kind)}">{html_lib.escape(c.kind)}</span>'
-            f" on <code>{html_lib.escape(c.subject)}</code>{params}</li>"
-        )
-    if not rows:
-        return ""
-    return (
-        f'<details open class="unary"><summary>Unary constraints ({len(rows)})</summary>'
-        f'<ul>{"".join(rows)}</ul></details>'
-    )
-
-
-# ---------------------------------------------------------------------------
-# Tasks panel
-# ---------------------------------------------------------------------------
-
-
-def _render_tasks_table(spec: ArenaEnvInitialGraphSpec) -> str:
-    if not spec.tasks:
-        return "<p class='muted'><em>No tasks defined.</em></p>"
-    rows = []
-    for i, t in enumerate(spec.tasks):
-        params_str = yaml.safe_dump(t.params, sort_keys=False).rstrip() if t.params else "(empty)"
-        desc = html_lib.escape(t.description or "")
-        rows.append(
-            "<tr>"
-            f"<td><code>{i}</code></td>"
-            f'<td><span class="badge type-task">{html_lib.escape(t.kind)}</span></td>'
-            f"<td>{desc}</td>"
-            f"<td><pre>{html_lib.escape(params_str)}</pre></td>"
-            "</tr>"
-        )
-    return (
-        "<table class='tasks'>"
-        "<thead><tr><th>#</th><th>kind</th><th>description</th><th>params</th></tr></thead>"
-        f"<tbody>{''.join(rows)}</tbody>"
-        "</table>"
-    )
-
-
-# ---------------------------------------------------------------------------
-# Node cards
-# ---------------------------------------------------------------------------
-
-
-def _render_node_cards(spec: ArenaEnvInitialGraphSpec) -> str:
-    return "\n".join(_render_one_node_card(node) for node in spec.nodes)
-
-
-def _render_one_node_card(node: ArenaEnvGraphNodeSpec) -> str:
-    node_dict = node.model_dump(mode="json", exclude_none=True)
-    node_yaml = yaml.safe_dump(node_dict, sort_keys=False).rstrip()
-    thumb = _render_node_thumbnail(node)
-    return f"""<article class="node-card type-{html_lib.escape(node.type.value)}">
-  {thumb}
-  <div class="node-meta">
-    <div class="node-id">{html_lib.escape(node.id)}</div>
-    <span class="badge type-{html_lib.escape(node.type.value)}">{html_lib.escape(node.type.value)}</span>
-  </div>
-  <pre class="node-yaml">{html_lib.escape(node_yaml)}</pre>
-</article>"""
-
-
-def _render_node_thumbnail(node: ArenaEnvGraphNodeSpec) -> str:
-    """Per-node placeholder thumbnail — two-letter initial."""
-    initial = (node.name[:2] if node.name else "?").upper()
-    return f"""<div class="thumb">
-    <span class="thumb-initial">{html_lib.escape(initial)}</span>
-    <span class="thumb-name">{html_lib.escape(node.name)}</span>
-  </div>"""
-
-
-# ---------------------------------------------------------------------------
-# Styling
-# ---------------------------------------------------------------------------
-
-_CSS = """
-:root {
-  --bg: #15181d;
-  --bg-elev: #1d2128;
-  --bg-elev2: #262b34;
-  --border: #2f343d;
-  --fg: #e4e6eb;
-  --fg-muted: #8a9099;
-  --accent: #7fd17f;
-}
-* { box-sizing: border-box; }
-body { margin: 0; padding: 24px; font: 14px/1.5 -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
-       background: var(--bg); color: var(--fg); }
-header { margin-bottom: 16px; }
-header h1 { margin: 0; font-size: 28px; font-weight: 700; }
-header .sub { margin: 4px 0 0; color: var(--fg-muted); font-size: 13px; }
-main { display: grid; grid-template-columns: 1fr 1fr; grid-template-rows: auto auto;
-       grid-template-areas: "graph nodes" "tasks nodes"; gap: 16px; }
-.graph-panel { grid-area: graph; }
-.tasks-panel { grid-area: tasks; }
-.nodes-panel { grid-area: nodes; }
-.panel { background: var(--bg-elev); border: 1px solid var(--border); border-radius: 8px; padding: 16px; }
-.panel h2 { margin: 0 0 12px; font-size: 16px; font-weight: 600; letter-spacing: 0.02em; }
-.panel h2 .muted { color: var(--fg-muted); font-weight: 400; font-size: 13px; }
-code { font-family: ui-monospace, 'SF Mono', Menlo, monospace; font-size: 12px;
-       background: var(--bg-elev2); padding: 1px 6px; border-radius: 4px; }
-pre { font-family: ui-monospace, 'SF Mono', Menlo, monospace; font-size: 12px;
-      background: var(--bg-elev2); padding: 10px 12px; border-radius: 6px; margin: 0;
-      white-space: pre-wrap; word-break: break-word; }
-.muted { color: var(--fg-muted); }
-.badge { display: inline-block; padding: 2px 8px; border-radius: 999px; font-size: 11px;
-         font-weight: 600; letter-spacing: 0.03em; background: var(--bg-elev2); color: var(--fg); }
-.badge.type-background { background: #3a4f7a; }
-.badge.type-embodiment { background: #7a3a3a; }
-.badge.type-object { background: #7a6b3a; }
-.badge.type-object_reference { background: #6b3a7a; }
-.badge.type-lighting { background: #3a7a7a; }
-.badge.type-is_anchor { background: #3a7d44; }
-.badge.type-position_limits, .badge.type-at_pose, .badge.type-at_position { background: #6b3a7a; }
-.badge.type-task { background: #2f343d; border: 1px solid #4a5; color: var(--accent); }
-.mermaid { background: var(--bg-elev2); padding: 8px; border-radius: 6px; min-height: 220px;
-           display: flex; align-items: center; justify-content: center; }
-.unary { margin-top: 12px; }
-.unary summary { cursor: pointer; color: var(--fg-muted); font-size: 13px; padding: 4px 0; }
-.unary ul { margin: 8px 0 0; padding-left: 20px; list-style: disc; color: var(--fg); }
-.unary li { padding: 3px 0; }
-table.tasks { width: 100%; border-collapse: collapse; }
-table.tasks th, table.tasks td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border);
-                                  vertical-align: top; font-size: 12px; }
-table.tasks th { color: var(--fg-muted); font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em; }
-table.tasks pre { padding: 6px 8px; font-size: 11px; }
-.node-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 12px; }
-.node-card { background: var(--bg-elev2); border: 1px solid var(--border); border-radius: 8px;
-             padding: 12px; display: flex; flex-direction: column; gap: 10px; }
-.node-card .thumb { aspect-ratio: 1 / 1; background: linear-gradient(135deg, #2a2f37, #1c2026);
-                    border-radius: 6px; display: flex; flex-direction: column;
-                    align-items: center; justify-content: center; color: var(--fg-muted);
-                    position: relative; overflow: hidden; }
-.node-card .thumb-rendered { background: #0e1115; }
-.node-card .thumb-rendered img { width: 100%; height: 100%; object-fit: contain; display: block; }
-.node-card .thumb-rendered .thumb-name { position: absolute; bottom: 0; left: 0; right: 0;
-                                         padding: 4px 6px; background: rgba(15, 17, 21, 0.78);
-                                         color: var(--fg); margin: 0; }
-.thumb-initial { font-size: 36px; font-weight: 700; color: var(--fg); opacity: 0.6;
-                 font-family: ui-monospace, monospace; }
-.thumb-name { font-size: 10px; margin-top: 6px; padding: 0 8px; text-align: center; word-break: break-word; }
-.node-meta { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
-.node-id { font-family: ui-monospace, monospace; font-size: 13px; font-weight: 600; word-break: break-all; }
-.node-yaml { font-size: 11px; }
-"""
-
-
-if __name__ == "__main__":
-    main()
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/__init__.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/__init__.py
new file mode 100644
index 000000000..821e672b4
--- /dev/null
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/__init__.py
@@ -0,0 +1,6 @@
+# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""Live editor and HTML dashboard for :class:`~isaaclab_arena.environments.arena_env_graph_spec.ArenaEnvInitialGraphSpec`."""
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/__init__.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/__init__.py
new file mode 100644
index 000000000..2fd363882
--- /dev/null
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/__init__.py
@@ -0,0 +1,6 @@
+# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""HTML rendering backend for the initial-graph review dashboard."""
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/html_document.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/html_document.py
new file mode 100644
index 000000000..d83c6b275
--- /dev/null
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/html_document.py
@@ -0,0 +1,54 @@
+# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+from __future__ import annotations
+
+import html as html_lib
+
+from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
+from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.mermaid_graph import render_mermaid_graph
+from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.panels import (
+    render_node_cards,
+    render_tasks_table,
+    render_unary_constraints,
+)
+from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.styles import DASHBOARD_CSS
+
+
+def render_html_for_spec(spec: ArenaEnvInitialGraphSpec) -> str:
+    """Render the self-contained review HTML dashboard for ``spec``."""
+    initial_state = spec.initial_state_spec
+    return f"""<!DOCTYPE html>
+<html lang="en">
+<head>
+<meta charset="utf-8">
+<title>{html_lib.escape(spec.env_name)} — graph review</title>
+<script src="https://cdn.jsdelivr.net/npm/mermaid@10/dist/mermaid.min.js"></script>
+<style>{DASHBOARD_CSS}</style>
+</head>
+<body>
+<header>
+  <h1>{html_lib.escape(spec.env_name)}</h1>
+  <p class="sub">{len(spec.nodes)} nodes · {len(spec.tasks)} tasks · initial state: <code>{html_lib.escape(initial_state.id)}</code></p>
+</header>
+<main>
+  <section class="panel graph-panel">
+    <h2>Spatial graph <span class="muted">(initial state: <code>{html_lib.escape(initial_state.id)}</code>)</span></h2>
+    <pre class="mermaid">{render_mermaid_graph(spec, initial_state)}</pre>
+    {render_unary_constraints(initial_state)}
+  </section>
+  <section class="panel tasks-panel">
+    <h2>Tasks</h2>
+    {render_tasks_table(spec)}
+  </section>
+  <section class="panel nodes-panel">
+    <h2>Nodes</h2>
+    <div class="node-grid">{render_node_cards(spec)}</div>
+  </section>
+</main>
+<script>mermaid.initialize({{ startOnLoad: true, theme: 'dark', themeVariables: {{ fontFamily: 'ui-monospace, monospace' }} }});</script>
+</body>
+</html>
+"""
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/mermaid_graph.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/mermaid_graph.py
new file mode 100644
index 000000000..21b57ce48
--- /dev/null
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/mermaid_graph.py
@@ -0,0 +1,96 @@
+# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+from __future__ import annotations
+
+import re
+
+from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
+from isaaclab_arena.environments.arena_env_graph_types import ArenaEnvGraphStateSpec
+
+_MERMAID_ID_SAFE = re.compile(r"[^A-Za-z0-9_]")
+
+
+def render_mermaid_graph(spec: ArenaEnvInitialGraphSpec, state: ArenaEnvGraphStateSpec) -> str:
+    """Emit a left-to-right mermaid graph of spatial and task constraints.
+
+    Binary spatial constraints (reference is set) are drawn as solid edges:
+        subject -->|kind| reference
+
+    Unary spatial constraints (no reference) are omitted from the graph and
+    listed below it by :func:`render_unary_constraints` so their params are
+    visible.
+
+    Task constraints with a child are drawn as dashed edges:
+        parent -.->|type| child
+
+    object_reference nodes are drawn with a dotted edge to their parent node:
+        ref_node -. ref .-> parent_node
+    """
+    lines = ["graph LR"]
+
+    anchor_ids: set[str] = set()
+    edge_nodes: set[str] = set()
+
+    for constraint in state.spatial_constraints:
+        kind = constraint.kind
+        if kind == "is_anchor":
+            anchor_ids.add(constraint.subject)
+        if constraint.reference is not None:
+            lines.append(
+                f"  {_mermaid_id(constraint.subject)}[{_mermaid_label(constraint.subject)}]"
+                f" -->|{kind}| "
+                f"{_mermaid_id(constraint.reference)}[{_mermaid_label(constraint.reference)}]"
+            )
+            edge_nodes.add(constraint.subject)
+            edge_nodes.add(constraint.reference)
+
+    for task_constraint in state.task_constraints:
+        if task_constraint.child is not None:
+            lines.append(
+                f"  {_mermaid_id(task_constraint.parent)}[{_mermaid_label(task_constraint.parent)}]"
+                f" -.->|{_mermaid_label(task_constraint.type.value)}| "
+                f"{_mermaid_id(task_constraint.child)}[{_mermaid_label(task_constraint.child)}]"
+            )
+            edge_nodes.add(task_constraint.parent)
+            edge_nodes.add(task_constraint.child)
+
+    for node in spec.nodes:
+        if node.id not in edge_nodes:
+            lines.append(f"  {_mermaid_id(node.id)}[{_mermaid_label(node.id)}]")
+
+    nodes_by_id = spec.nodes_by_id
+    for node in spec.nodes:
+        if node.type.value == "object_reference" and node.parent is not None:
+            if node.parent in nodes_by_id:
+                lines.append(f"  {_mermaid_id(node.id)} -.->|ref| {_mermaid_id(node.parent)}")
+
+    for anchor_id in anchor_ids:
+        lines.append(f"  style {_mermaid_id(anchor_id)} fill:#3a7d44,color:#fff,stroke:#7fd17f,stroke-width:2px")
+
+    type_palette = {
+        "background": ("#3a4f7a", "#7aa0d8"),
+        "embodiment": ("#7a3a3a", "#d87a7a"),
+        "object": ("#7a6b3a", "#d8c47a"),
+        "object_reference": ("#6b3a7a", "#c47ad8"),
+        "lighting": ("#3a7a7a", "#7ad8d8"),
+    }
+    for node in spec.nodes:
+        if node.id in anchor_ids:
+            continue
+        fill, stroke = type_palette.get(node.type.value, ("#3a3d44", "#888"))
+        lines.append(f"  style {_mermaid_id(node.id)} fill:{fill},color:#fff,stroke:{stroke}")
+
+    return "\n".join(lines)
+
+
+def _mermaid_id(value: str) -> str:
+    """Mermaid node identifiers must be alphanumeric / underscore."""
+    return _MERMAID_ID_SAFE.sub("_", value)
+
+
+def _mermaid_label(value: str) -> str:
+    """Escape mermaid-significant characters inside node labels."""
+    return value.replace('"', "&quot;").replace("|", "&#124;")
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/panels.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/panels.py
new file mode 100644
index 000000000..901b4c331
--- /dev/null
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/panels.py
@@ -0,0 +1,80 @@
+# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+from __future__ import annotations
+
+import html as html_lib
+import yaml
+
+from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
+from isaaclab_arena.environments.arena_env_graph_types import ArenaEnvGraphNodeSpec, ArenaEnvGraphStateSpec
+from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.thumbnails import (
+    render_placeholder_thumbnail,
+)
+
+
+def render_unary_constraints(state: ArenaEnvGraphStateSpec) -> str:
+    """List constraints without a reference below the graph (anchors, position_limits, ...)."""
+    rows = []
+    for constraint in state.spatial_constraints:
+        if constraint.reference is not None:
+            continue
+        params = (
+            " <code"
+            f' class="muted">{html_lib.escape(yaml.safe_dump(constraint.params, default_flow_style=True).rstrip())}</code>'
+            if constraint.params
+            else ""
+        )
+        rows.append(
+            f'<li><span class="badge type-{html_lib.escape(constraint.kind)}">{html_lib.escape(constraint.kind)}</span>'
+            f" on <code>{html_lib.escape(constraint.subject)}</code>{params}</li>"
+        )
+    if not rows:
+        return ""
+    return (
+        f'<details open class="unary"><summary>Unary constraints ({len(rows)})</summary>'
+        f'<ul>{"".join(rows)}</ul></details>'
+    )
+
+
+def render_tasks_table(spec: ArenaEnvInitialGraphSpec) -> str:
+    if not spec.tasks:
+        return "<p class='muted'><em>No tasks defined.</em></p>"
+    rows = []
+    for index, task in enumerate(spec.tasks):
+        params_str = yaml.safe_dump(task.params, sort_keys=False).rstrip() if task.params else "(empty)"
+        description = html_lib.escape(task.description or "")
+        rows.append(
+            "<tr>"
+            f"<td><code>{index}</code></td>"
+            f'<td><span class="badge type-task">{html_lib.escape(task.kind)}</span></td>'
+            f"<td>{description}</td>"
+            f"<td><pre>{html_lib.escape(params_str)}</pre></td>"
+            "</tr>"
+        )
+    return (
+        "<table class='tasks'>"
+        "<thead><tr><th>#</th><th>kind</th><th>description</th><th>params</th></tr></thead>"
+        f"<tbody>{''.join(rows)}</tbody>"
+        "</table>"
+    )
+
+
+def render_node_cards(spec: ArenaEnvInitialGraphSpec) -> str:
+    return "\n".join(render_node_card(node) for node in spec.nodes)
+
+
+def render_node_card(node: ArenaEnvGraphNodeSpec) -> str:
+    node_dict = node.model_dump(mode="json", exclude_none=True)
+    node_yaml = yaml.safe_dump(node_dict, sort_keys=False).rstrip()
+    thumb = render_placeholder_thumbnail(node)
+    return f"""<article class="node-card type-{html_lib.escape(node.type.value)}">
+  {thumb}
+  <div class="node-meta">
+    <div class="node-id">{html_lib.escape(node.id)}</div>
+    <span class="badge type-{html_lib.escape(node.type.value)}">{html_lib.escape(node.type.value)}</span>
+  </div>
+  <pre class="node-yaml">{html_lib.escape(node_yaml)}</pre>
+</article>"""
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/styles.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/styles.py
new file mode 100644
index 000000000..279ad349d
--- /dev/null
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/styles.py
@@ -0,0 +1,75 @@
+# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+DASHBOARD_CSS = """
+:root {
+  --bg: #15181d;
+  --bg-elev: #1d2128;
+  --bg-elev2: #262b34;
+  --border: #2f343d;
+  --fg: #e4e6eb;
+  --fg-muted: #8a9099;
+  --accent: #7fd17f;
+}
+* { box-sizing: border-box; }
+body { margin: 0; padding: 24px; font: 14px/1.5 -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
+       background: var(--bg); color: var(--fg); }
+header { margin-bottom: 16px; }
+header h1 { margin: 0; font-size: 28px; font-weight: 700; }
+header .sub { margin: 4px 0 0; color: var(--fg-muted); font-size: 13px; }
+main { display: grid; grid-template-columns: 1fr 1fr; grid-template-rows: auto auto;
+       grid-template-areas: "graph nodes" "tasks nodes"; gap: 16px; }
+.graph-panel { grid-area: graph; }
+.tasks-panel { grid-area: tasks; }
+.nodes-panel { grid-area: nodes; }
+.panel { background: var(--bg-elev); border: 1px solid var(--border); border-radius: 8px; padding: 16px; }
+.panel h2 { margin: 0 0 12px; font-size: 16px; font-weight: 600; letter-spacing: 0.02em; }
+.panel h2 .muted { color: var(--fg-muted); font-weight: 400; font-size: 13px; }
+code { font-family: ui-monospace, 'SF Mono', Menlo, monospace; font-size: 12px;
+       background: var(--bg-elev2); padding: 1px 6px; border-radius: 4px; }
+pre { font-family: ui-monospace, 'SF Mono', Menlo, monospace; font-size: 12px;
+      background: var(--bg-elev2); padding: 10px 12px; border-radius: 6px; margin: 0;
+      white-space: pre-wrap; word-break: break-word; }
+.muted { color: var(--fg-muted); }
+.badge { display: inline-block; padding: 2px 8px; border-radius: 999px; font-size: 11px;
+         font-weight: 600; letter-spacing: 0.03em; background: var(--bg-elev2); color: var(--fg); }
+.badge.type-background { background: #3a4f7a; }
+.badge.type-embodiment { background: #7a3a3a; }
+.badge.type-object { background: #7a6b3a; }
+.badge.type-object_reference { background: #6b3a7a; }
+.badge.type-lighting { background: #3a7a7a; }
+.badge.type-is_anchor { background: #3a7d44; }
+.badge.type-position_limits, .badge.type-at_pose, .badge.type-at_position { background: #6b3a7a; }
+.badge.type-task { background: #2f343d; border: 1px solid #4a5; color: var(--accent); }
+.mermaid { background: var(--bg-elev2); padding: 8px; border-radius: 6px; min-height: 220px;
+           display: flex; align-items: center; justify-content: center; }
+.unary { margin-top: 12px; }
+.unary summary { cursor: pointer; color: var(--fg-muted); font-size: 13px; padding: 4px 0; }
+.unary ul { margin: 8px 0 0; padding-left: 20px; list-style: disc; color: var(--fg); }
+.unary li { padding: 3px 0; }
+table.tasks { width: 100%; border-collapse: collapse; }
+table.tasks th, table.tasks td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border);
+                                  vertical-align: top; font-size: 12px; }
+table.tasks th { color: var(--fg-muted); font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em; }
+table.tasks pre { padding: 6px 8px; font-size: 11px; }
+.node-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 12px; }
+.node-card { background: var(--bg-elev2); border: 1px solid var(--border); border-radius: 8px;
+             padding: 12px; display: flex; flex-direction: column; gap: 10px; }
+.node-card .thumb { aspect-ratio: 1 / 1; background: linear-gradient(135deg, #2a2f37, #1c2026);
+                    border-radius: 6px; display: flex; flex-direction: column;
+                    align-items: center; justify-content: center; color: var(--fg-muted);
+                    position: relative; overflow: hidden; }
+.node-card .thumb-rendered { background: #0e1115; }
+.node-card .thumb-rendered img { width: 100%; height: 100%; object-fit: contain; display: block; }
+.node-card .thumb-rendered .thumb-name { position: absolute; bottom: 0; left: 0; right: 0;
+                                         padding: 4px 6px; background: rgba(15, 17, 21, 0.78);
+                                         color: var(--fg); margin: 0; }
+.thumb-initial { font-size: 36px; font-weight: 700; color: var(--fg); opacity: 0.6;
+                 font-family: ui-monospace, monospace; }
+.thumb-name { font-size: 10px; margin-top: 6px; padding: 0 8px; text-align: center; word-break: break-word; }
+.node-meta { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
+.node-id { font-family: ui-monospace, monospace; font-size: 13px; font-weight: 600; word-break: break-all; }
+.node-yaml { font-size: 11px; }
+"""
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/thumbnails.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/thumbnails.py
new file mode 100644
index 000000000..f2742ee8f
--- /dev/null
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/thumbnails.py
@@ -0,0 +1,20 @@
+# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+from __future__ import annotations
+
+import html as html_lib
+
+from isaaclab_arena.environments.arena_env_graph_types import ArenaEnvGraphNodeSpec
+
+
+# TODO(qianl): Replace placeholder thumbnails with sim-rendered snapshots .
+def render_placeholder_thumbnail(node: ArenaEnvGraphNodeSpec) -> str:
+    """Per-node placeholder thumbnail — two-letter initial."""
+    initial = (node.name[:2] if node.name else "?").upper()
+    return f"""<div class="thumb">
+    <span class="thumb-initial">{html_lib.escape(initial)}</span>
+    <span class="thumb-name">{html_lib.escape(node.name)}</span>
+  </div>"""
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/server.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/server.py
new file mode 100644
index 000000000..4212cf6a7
--- /dev/null
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/server.py
@@ -0,0 +1,85 @@
+# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""CLI launcher for the ArenaEnvInitialGraphSpec live editor.
+
+Spawns Streamlit with :mod:`~isaaclab_arena_examples.agentic_environment_generation.review_gui.streamlit_ui`.
+
+Usage:
+    /isaac-sim/python.sh -m isaaclab_arena_examples.agentic_environment_generation.review_gui.server \\
+        --yaml isaaclab_arena/tests/test_data/pick_and_place_maple_table_init_env_graph.yaml
+
+    # Custom port:
+    /isaac-sim/python.sh -m isaaclab_arena_examples.agentic_environment_generation.review_gui.server \\
+        --yaml <path> --port 8600
+"""
+
+from __future__ import annotations
+
+import argparse
+import os
+import subprocess
+import sys
+from pathlib import Path
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(
+        description=__doc__,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    parser.add_argument(
+        "--yaml",
+        type=Path,
+        required=True,
+        help="Path to an ArenaEnvInitialGraphSpec YAML file.",
+    )
+    parser.add_argument(
+        "--port",
+        type=int,
+        default=8501,
+        help="Streamlit server port (default: 8501).",
+    )
+    args = parser.parse_args()
+    serve_live_editor(args.yaml, port=args.port)
+
+
+def serve_live_editor(yaml_path: Path, port: int = 8501) -> None:
+    """Spawn ``streamlit run streamlit_ui.py -- --yaml <path>`` and wait."""
+    app_path = Path(__file__).with_name("streamlit_ui.py")
+    if not app_path.exists():
+        raise FileNotFoundError(f"Streamlit app not found at {app_path} — installation is incomplete.")
+
+    cmd = [
+        sys.executable,
+        "-m",
+        "streamlit",
+        "run",
+        str(app_path),
+        "--server.port",
+        str(port),
+        "--browser.gatherUsageStats",
+        "false",
+        "--server.fileWatcherType",
+        "none",
+        "--",
+        "--yaml",
+        str(yaml_path.resolve()),
+    ]
+
+    print(f"[review_gui] launching Streamlit live editor: {' '.join(cmd)}", file=sys.stderr)
+    try:
+        subprocess.run(cmd, env=os.environ.copy(), check=True)
+    except FileNotFoundError as exc:
+        raise SystemExit(
+            "Streamlit is not installed. Inside the isaaclab_arena container run:\n"
+            "  python -m pip install --user --ignore-installed streamlit streamlit-ace"
+        ) from exc
+    except KeyboardInterrupt:
+        pass
+
+
+if __name__ == "__main__":
+    main()
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_app.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
similarity index 53%
rename from isaaclab_arena_examples/agentic_environment_generation/review_app.py
rename to isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
index 1e51132d7..c234d14f3 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_app.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
@@ -3,22 +3,12 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
-"""Streamlit-backed live editor for ArenaEnvInitialGraphSpec YAMLs.
-
-Wraps :func:`isaaclab_arena.agentic_environment_generation.review_graph.render_html_for_spec`
-in a two-pane Streamlit page so the user can edit the ``ArenaEnvInitialGraphSpec``
-YAML directly in the browser and see the visualization update automatically.
-
-Launch (always via the wrapper in review_graph.py — handles streamlit flags):
-    /isaac-sim/python.sh -m isaaclab_arena.agentic_environment_generation.review_graph \\
-        --yaml path/to/spec.yaml
-
-Design:
-  * Left pane — ``streamlit-ace`` YAML editor + validation badge + Save button.
-    Validation runs on every rerun (i.e. after each editor blur). When the YAML
-    is valid and has changed since the last render, the visualization updates
-    automatically — no button click required.
-  * Right pane — sandboxed iframe with the rendered review HTML.
+"""Streamlit UI for the initial-graph live editor.
+
+Launch via :mod:`~isaaclab_arena_examples.agentic_environment_generation.review_gui.server`:
+
+    /isaac-sim/python.sh -m isaaclab_arena_examples.agentic_environment_generation.review_gui.server \\
+        --yaml isaaclab_arena/tests/test_data/pick_and_place_maple_table_init_env_graph.yaml
 """
 
 from __future__ import annotations
@@ -31,32 +21,24 @@
 
 import streamlit as st
 
-from isaaclab_arena.agentic_environment_generation.review_graph import render_html_for_spec
 from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
+from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.html_document import render_html_for_spec
 
 # Visualization iframe height. Tuned so the graph + tasks + node grid all
 # fit without an outer Streamlit scrollbar swallowing the inner one.
 _IFRAME_HEIGHT_PX = 1100
 
-
-# ---------------------------------------------------------------------------
-# Args + session-state init
-# ---------------------------------------------------------------------------
-
-
-def _parse_args() -> argparse.Namespace:
-    parser = argparse.ArgumentParser(description=__doc__)
-    parser.add_argument(
-        "--yaml",
-        type=Path,
-        required=True,
-        help="Path to the ArenaEnvInitialGraphSpec YAML to open in the editor.",
-    )
-    return parser.parse_args()
+_BROKEN_PLACEHOLDER_HTML = """<!DOCTYPE html><html><body style="
+    font-family: ui-monospace, monospace;
+    background:#15181d; color:#e4e6eb; padding:24px; margin:0;">
+<p>No visualization yet — fix the YAML errors to auto-render.</p>
+</body></html>"""
 
 
 @dataclass
-class _ValidationResult:
+class ValidationResult:
+    """Outcome of parsing and validating YAML text as an initial graph spec."""
+
     spec: ArenaEnvInitialGraphSpec | None
     error: str | None
 
@@ -65,21 +47,29 @@ def is_valid(self) -> bool:
         return self.spec is not None
 
 
-def _validate_yaml_text(text: str) -> _ValidationResult:
+def validate_yaml_text(text: str) -> ValidationResult:
+    """Parse ``text`` as YAML and validate it as an :class:`ArenaEnvInitialGraphSpec`."""
     try:
         raw = yaml.safe_load(text)
         spec = ArenaEnvInitialGraphSpec.model_validate(raw)
-        return _ValidationResult(spec=spec, error=None)
+        return ValidationResult(spec=spec, error=None)
     except Exception:
-        return _ValidationResult(spec=None, error=traceback.format_exc())
+        return ValidationResult(spec=None, error=traceback.format_exc())
+
 
+def parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument(
+        "--yaml",
+        type=Path,
+        required=True,
+        help="Path to the ArenaEnvInitialGraphSpec YAML to open in the editor.",
+    )
+    return parser.parse_args()
 
-def _initialize_state(yaml_path: Path) -> None:
-    """Seed ``st.session_state`` from disk exactly once per session.
 
-    We key off ``_yaml_path`` so that if the user passes a different YAML on
-    a Streamlit reload (rare — usually the same), we reset cleanly.
-    """
+def initialize_state(yaml_path: Path) -> None:
+    """Seed ``st.session_state`` from disk exactly once per session."""
     if st.session_state.get("_yaml_path") == str(yaml_path):
         return
 
@@ -88,37 +78,17 @@ def _initialize_state(yaml_path: Path) -> None:
     st.session_state["_yaml_path"] = str(yaml_path)
     st.session_state["original_text"] = original_text
     st.session_state["edited_text"] = original_text
-    # The text whose render is currently displayed. Starts == original so the
-    # first paint shows the on-disk file (and "Regenerate" is correctly
-    # disabled until the user edits something).
     st.session_state["last_rendered_text"] = original_text
     st.session_state["save_path"] = str(yaml_path)
 
-    initial = _validate_yaml_text(original_text)
+    initial = validate_yaml_text(original_text)
     if not initial.is_valid:
-        # Defensive: if the on-disk file is already broken we still want to
-        # show *something*, but we won't pre-render it. The user fixes the
-        # YAML in the editor, then hits Regenerate.
         st.session_state["rendered_html"] = _BROKEN_PLACEHOLDER_HTML
     else:
         st.session_state["rendered_html"] = render_html_for_spec(initial.spec)
 
 
-# Tiny standalone HTML used when the on-disk YAML is itself invalid.
-_BROKEN_PLACEHOLDER_HTML = """<!DOCTYPE html><html><body style="
-    font-family: ui-monospace, monospace;
-    background:#15181d; color:#e4e6eb; padding:24px; margin:0;">
-<p>No visualization yet — fix the YAML errors to auto-render.</p>
-</body></html>"""
-
-
-# ---------------------------------------------------------------------------
-# UI panels
-# ---------------------------------------------------------------------------
-
-
-def _render_validation_badge(validation: _ValidationResult) -> None:
-    """Show a green tick + summary, or a red cross + the raw exception text."""
+def render_validation_badge(validation: ValidationResult) -> None:
     if validation.is_valid:
         spec = validation.spec
         st.success(
@@ -130,8 +100,7 @@ def _render_validation_badge(validation: _ValidationResult) -> None:
         st.error(f"Invalid YAML\n\n```\n{validation.error}\n```", icon="🛑")
 
 
-def _render_save_button(validation: _ValidationResult) -> None:
-    """Render the Save button. Disabled while the YAML is invalid."""
+def render_save_button(validation: ValidationResult) -> None:
     can_save = validation.is_valid
     save_path_str = st.session_state["save_path"]
 
@@ -143,7 +112,6 @@ def _render_save_button(validation: _ValidationResult) -> None:
     ):
         try:
             Path(save_path_str).write_text(st.session_state["edited_text"], encoding="utf-8")
-            # Update "original" so future comparisons are against the saved file.
             st.session_state["original_text"] = st.session_state["edited_text"]
             st.toast(f"Saved → {save_path_str}", icon="💾")
         except OSError as exc:
@@ -160,21 +128,10 @@ def _render_save_button(validation: _ValidationResult) -> None:
             st.session_state["save_path"] = new_path
 
 
-def _render_editor_panel(yaml_path: Path) -> _ValidationResult:
-    """Left pane. Returns the validation result for the current editor text.
-
-    Returning the validation result (rather than stashing it in session_state)
-    keeps the data flow inside one render pass and avoids a stale-state class
-    of bug where the badge and the buttons disagree.
-    """
-    # Lazy import so the module is importable from environments that don't
-    # have streamlit-ace installed yet (we surface a clean error message
-    # rather than ImportError at module load).
+def render_editor_panel(yaml_path: Path) -> ValidationResult:
     try:
         from streamlit_ace import st_ace  # noqa: PLC0415
     except ImportError as exc:
-        # See review_graph._serve_live_editor for why --user --ignore-installed
-        # is required inside the isaaclab_arena container.
         st.error(
             "`streamlit-ace` is not installed. Inside the isaaclab_arena container run:\n"
             "`python -m pip install --user --ignore-installed streamlit-ace`\n\n"
@@ -186,8 +143,6 @@ def _render_editor_panel(yaml_path: Path) -> _ValidationResult:
     st.subheader("YAML editor")
     st.caption(f"Source: `{yaml_path}`")
 
-    # ``auto_update=False`` commits on blur / Ctrl+Enter rather than on every
-    # keystroke, showing an "Apply" button in the editor toolbar.
     new_text = st_ace(
         value=st.session_state["edited_text"],
         language="yaml",
@@ -200,20 +155,14 @@ def _render_editor_panel(yaml_path: Path) -> _ValidationResult:
         wrap=False,
         auto_update=False,
         min_lines=30,
-        # Key bound to the YAML path so swapping --yaml between sessions
-        # forces ace to remount with the new content.
         key=f"ace_editor::{yaml_path}",
     )
     if new_text is not None:
         st.session_state["edited_text"] = new_text
 
-    validation = _validate_yaml_text(st.session_state["edited_text"])
-    _render_validation_badge(validation)
+    validation = validate_yaml_text(st.session_state["edited_text"])
+    render_validation_badge(validation)
 
-    # Auto-render whenever the YAML is valid and has changed since the last
-    # render. This runs before the right pane is drawn, so the updated HTML
-    # is already in session_state when the iframe is mounted — no extra rerun
-    # needed.
     edited_since_render = st.session_state["edited_text"] != st.session_state["last_rendered_text"]
     if validation.is_valid and edited_since_render:
         with st.spinner("Rendering visualization…"):
@@ -221,18 +170,14 @@ def _render_editor_panel(yaml_path: Path) -> _ValidationResult:
         st.session_state["last_rendered_text"] = st.session_state["edited_text"]
         st.toast("Visualization updated.", icon="🔄")
 
-    _render_save_button(validation)
+    render_save_button(validation)
     return validation
 
 
-def _render_visualization_panel() -> None:
-    """Right pane — iframe-mount the cached rendered HTML."""
+def render_visualization_panel() -> None:
     st.subheader("Visualization")
     st.caption("Updates automatically when the YAML is valid.")
 
-    # ``st.components.v1.html`` wraps the payload in a sandboxed iframe, which
-    # is what we want — the mermaid CDN script and the static CSS stay
-    # isolated from Streamlit's own DOM.
     st.components.v1.html(
         st.session_state["rendered_html"],
         height=_IFRAME_HEIGHT_PX,
@@ -240,11 +185,6 @@ def _render_visualization_panel() -> None:
     )
 
 
-# ---------------------------------------------------------------------------
-# Entry point
-# ---------------------------------------------------------------------------
-
-
 def main() -> None:
     st.set_page_config(
         page_title="ArenaEnvInitialGraphSpec live editor",
@@ -252,24 +192,21 @@ def main() -> None:
         initial_sidebar_state="collapsed",
     )
 
-    args = _parse_args()
+    args = parse_args()
     yaml_path = args.yaml.resolve()
     if not yaml_path.exists():
         st.error(f"YAML file not found: {yaml_path}", icon="🛑")
         st.stop()
 
-    _initialize_state(yaml_path)
+    initialize_state(yaml_path)
 
     st.markdown("### ArenaEnvInitialGraphSpec live editor")
     left, right = st.columns([2, 3], gap="large")
     with left:
-        _render_editor_panel(yaml_path)
+        render_editor_panel(yaml_path)
     with right:
-        _render_visualization_panel()
+        render_visualization_panel()
 
 
-# Streamlit invokes the script top-level on every rerun, so we run main()
-# unconditionally. The standard ``if __name__ == "__main__"`` guard would
-# also work under ``streamlit run`` but is unnecessary — this module is only
-# ever loaded as the Streamlit entrypoint.
+# Streamlit invokes the script top-level on every rerun.
 main()

From 8d5ecabffca185d38e66f3adac68764afb12f51d Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Mon, 15 Jun 2026 03:34:24 -0700
Subject: [PATCH 06/19] Rename review_gui render module to dashboard.

Replace html_document.render_html_for_spec with dashboard.render_dashboard_html.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../review_gui/render/{html_document.py => dashboard.py}    | 4 ++--
 .../review_gui/streamlit_ui.py                              | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)
 rename isaaclab_arena_examples/agentic_environment_generation/review_gui/render/{html_document.py => dashboard.py} (93%)

diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/html_document.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/dashboard.py
similarity index 93%
rename from isaaclab_arena_examples/agentic_environment_generation/review_gui/render/html_document.py
rename to isaaclab_arena_examples/agentic_environment_generation/review_gui/render/dashboard.py
index d83c6b275..a4318c3d3 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/html_document.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/dashboard.py
@@ -17,8 +17,8 @@
 from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.styles import DASHBOARD_CSS
 
 
-def render_html_for_spec(spec: ArenaEnvInitialGraphSpec) -> str:
-    """Render the self-contained review HTML dashboard for ``spec``."""
+def render_dashboard_html(spec: ArenaEnvInitialGraphSpec) -> str:
+    """Render the self-contained review dashboard HTML for ``spec``."""
     initial_state = spec.initial_state_spec
     return f"""<!DOCTYPE html>
 <html lang="en">
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
index c234d14f3..cbbab13ee 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
@@ -22,7 +22,7 @@
 import streamlit as st
 
 from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
-from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.html_document import render_html_for_spec
+from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.dashboard import render_dashboard_html
 
 # Visualization iframe height. Tuned so the graph + tasks + node grid all
 # fit without an outer Streamlit scrollbar swallowing the inner one.
@@ -85,7 +85,7 @@ def initialize_state(yaml_path: Path) -> None:
     if not initial.is_valid:
         st.session_state["rendered_html"] = _BROKEN_PLACEHOLDER_HTML
     else:
-        st.session_state["rendered_html"] = render_html_for_spec(initial.spec)
+        st.session_state["rendered_html"] = render_dashboard_html(initial.spec)
 
 
 def render_validation_badge(validation: ValidationResult) -> None:
@@ -166,7 +166,7 @@ def render_editor_panel(yaml_path: Path) -> ValidationResult:
     edited_since_render = st.session_state["edited_text"] != st.session_state["last_rendered_text"]
     if validation.is_valid and edited_since_render:
         with st.spinner("Rendering visualization…"):
-            st.session_state["rendered_html"] = render_html_for_spec(validation.spec)
+            st.session_state["rendered_html"] = render_dashboard_html(validation.spec)
         st.session_state["last_rendered_text"] = st.session_state["edited_text"]
         st.toast("Visualization updated.", icon="🔄")
 

From 2989b7e33a32625a7023eb2e0166bef10cf2b331 Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Mon, 15 Jun 2026 08:26:46 -0700
Subject: [PATCH 07/19] Add SimApp sidecar for fast registry-backed YAML
 validation in review GUI.

Route TaskRegistry and relation checks through a persistent Kit subprocess
so Streamlit re-validation stays fast after the first boot, and rebuild
validated specs locally via skip_registry context.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../environments/arena_env_graph_spec.py      |   6 +-
 .../environments/arena_env_graph_types.py     |  10 +-
 .../review_gui/simapp_sidecar.py              | 175 ++++++++++++++++++
 .../review_gui/simapp_sidecar_client.py       | 156 ++++++++++++++++
 .../review_gui/streamlit_ui.py                |  82 +++++++-
 5 files changed, 418 insertions(+), 11 deletions(-)
 create mode 100644 isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
 create mode 100644 isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py

diff --git a/isaaclab_arena/environments/arena_env_graph_spec.py b/isaaclab_arena/environments/arena_env_graph_spec.py
index c11c09656..6176357f9 100644
--- a/isaaclab_arena/environments/arena_env_graph_spec.py
+++ b/isaaclab_arena/environments/arena_env_graph_spec.py
@@ -9,7 +9,7 @@
 from pathlib import Path
 from typing import TYPE_CHECKING, Any, Self
 
-from pydantic import BaseModel, Field, SerializeAsAny, field_validator, model_validator
+from pydantic import BaseModel, Field, SerializeAsAny, ValidationInfo, field_validator, model_validator
 
 from isaaclab_arena.assets.registries import TaskRegistry
 from isaaclab_arena.environments.arena_env_graph_types import (
@@ -170,8 +170,10 @@ class ArenaEnvInitialGraphSpec(ArenaEnvGraphSpecBase):
     initial_state_spec: ArenaEnvGraphStateSpec
 
     @model_validator(mode="after")
-    def validate(self) -> Self:
+    def validate(self, info: ValidationInfo) -> Self:
         """Check unique IDs, constraint references, and spatial constraint shapes."""
+        if info.context and info.context.get("skip_registry"):
+            return self
         assert_unique_ids(self.nodes, [], [self.initial_state_spec])
         assert_constraint_references(self.nodes, [self.initial_state_spec])
         assert_spatial_constraint_shapes([self.initial_state_spec])
diff --git a/isaaclab_arena/environments/arena_env_graph_types.py b/isaaclab_arena/environments/arena_env_graph_types.py
index 740f6a642..38e121175 100644
--- a/isaaclab_arena/environments/arena_env_graph_types.py
+++ b/isaaclab_arena/environments/arena_env_graph_types.py
@@ -16,7 +16,7 @@
 from enum import Enum
 from typing import Any
 
-from pydantic import BaseModel, Field, field_validator, model_validator
+from pydantic import BaseModel, Field, ValidationInfo, field_validator, model_validator
 
 from isaaclab_arena.assets.object_type import ObjectType
 from isaaclab_arena.assets.registries import ObjectRelationLibraryRegistry, TaskRegistry
@@ -115,7 +115,9 @@ class TaskSpec(BaseModel):
 
     @field_validator("kind")
     @classmethod
-    def _validate_registered_task_type(cls, value: str) -> str:
+    def _validate_registered_task_type(cls, value: str, info: ValidationInfo) -> str:
+        if info.context and info.context.get("skip_registry"):
+            return value
         registry = TaskRegistry()
         assert registry.is_registered(value), f"Unknown task kind '{value}'"
         return value
@@ -169,7 +171,9 @@ class SpatialRelationSpec(BaseModel):
     )
 
     @model_validator(mode="after")
-    def _validate_kind_and_arity(self) -> SpatialRelationSpec:
+    def _validate_kind_and_arity(self, info: ValidationInfo) -> SpatialRelationSpec:
+        if info.context and info.context.get("skip_registry"):
+            return self
         registry = ObjectRelationLibraryRegistry()
         assert registry.is_registered(self.kind), f"Unknown relation kind '{self.kind}'"
         relation_cls = registry.get_object_relation_by_name(self.kind)
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
new file mode 100644
index 000000000..ee107cc75
--- /dev/null
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
@@ -0,0 +1,175 @@
+# Copyright (c) 2025-2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""Long-lived ``SimulationApp`` host process for the live review editor.
+
+Boots Kit's ``SimulationApp`` once on *its own* main thread and serves
+spec-validation requests over a newline-delimited JSON-RPC pipe on
+stdin/stdout. The parent (``streamlit_ui.py`` running inside Streamlit) spawns
+exactly one of these and reuses it for the entire server lifetime via
+:class:`isaaclab_arena_examples.agentic_environment_generation.review_gui.simapp_sidecar_client.SimAppSidecar`.
+
+Why a sidecar and not an in-process ``SimulationApp``:
+
+* ``signal.signal`` only works in the main thread. Streamlit's
+  ``ScriptRunner`` runs the script in a worker thread, so SimApp's signal
+  setup raises ``ValueError("signal only works in main thread …")``.
+* Registry imports transitively load ``pxr``, which must happen only after
+  ``SimulationApp`` starts. A dedicated process keeps that ordering safe.
+
+Protocol (newline-delimited JSON over stdin/stdout):
+
+  Ready handshake (sent by sidecar on boot before reading any request):
+    {"ready": true}                          # SimApp boot succeeded
+    {"ready": false, "error": "..."}         # boot failed; sidecar exits
+
+  Requests:
+    {"cmd": "ping"}
+      → {"ok": true}
+
+    {"cmd": "validate_spec", "yaml_text": "..."}
+      → {"ok": true, "spec_dict": {...}}
+        (full :class:`ArenaEnvInitialGraphSpec` validation including registry
+         lookups — runs in the sidecar where registries are already warm)
+
+    {"cmd": "shutdown"}
+      → {"ok": true}   # sidecar exits cleanly after replying
+
+  Parent EOF on stdin (parent process died) triggers the same graceful
+  shutdown as the explicit "shutdown" cmd.
+
+stdout multiplexing:
+
+Kit writes a lot to stdout (warnings, replicator startup, etc.) and that
+would corrupt the JSON channel the parent reads. We dup the original
+stdout fd before touching Kit, then redirect Kit's stdout to stderr —
+JSON replies go out through the saved fd; everything else from Kit
+appears on the user's terminal via inherited stderr.
+"""
+
+from __future__ import annotations
+
+import argparse
+import contextlib
+import json
+import os
+import signal
+import sys
+import traceback
+import yaml
+from typing import Any
+
+# ---------------------------------------------------------------------------
+# stdout multiplexing setup — run BEFORE importing anything that might
+# touch Kit or print to stdout, otherwise Kit's chatter pollutes the JSON
+# channel and the parent crashes on the first bad json.loads.
+# ---------------------------------------------------------------------------
+
+_JSON_FD = os.dup(1)  # save real stdout for our JSON channel
+os.dup2(2, 1)
+sys.stdout = sys.stderr
+
+
+def _send(payload: dict[str, Any]) -> None:
+    """Write one JSON line to the parent on the saved stdout fd."""
+    data = (json.dumps(payload) + "\n").encode("utf-8")
+    os.write(_JSON_FD, data)
+
+
+def _launch_simulation_app():
+    """Boot Isaac Sim's ``SimulationApp`` for registry-backed validation."""
+    try:
+        from isaaclab_arena.utils.isaaclab_utils.simulation_app import get_app_launcher  # noqa: PLC0415
+
+        sim_args = argparse.Namespace(headless=True, enable_cameras=False, hide_ui=True, livestream=-1)
+        return get_app_launcher(sim_args).app
+    except Exception as exc:
+        print(f"[simapp_sidecar] SimulationApp launch failed: {exc}", file=sys.stderr)
+        return None
+
+
+def _install_signal_handlers() -> None:
+    def _exit(signum, _frame):
+        raise SystemExit(0)
+
+    signal.signal(signal.SIGTERM, _exit)
+    signal.signal(signal.SIGINT, _exit)
+
+
+def _serve() -> int:
+    """Boot SimApp, hand-shake with the parent, then service validation requests."""
+    _install_signal_handlers()
+
+    app = _launch_simulation_app()
+    if app is None:
+        _send({"ready": False, "error": "SimulationApp launch returned None"})
+        return 1
+
+    from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec  # noqa: PLC0415
+
+    _send({"ready": True})
+
+    try:
+        for raw_line in sys.stdin:
+            line = raw_line.strip()
+            if not line:
+                continue
+            try:
+                req = json.loads(line)
+            except json.JSONDecodeError as exc:
+                _send({"ok": False, "error": f"bad json: {exc}"})
+                continue
+
+            cmd = req.get("cmd")
+            if cmd == "shutdown":
+                _send({"ok": True})
+                return 0
+
+            if cmd == "ping":
+                _send({"ok": True})
+                continue
+
+            if cmd == "validate_spec":
+                _send(_handle_validate_spec(req, ArenaEnvInitialGraphSpec))
+                continue
+
+            _send({"ok": False, "error": f"unknown cmd: {cmd!r}"})
+
+        return 0
+    finally:
+        with contextlib.suppress(Exception):
+            app.close()
+
+
+def _handle_validate_spec(req: dict[str, Any], spec_cls) -> dict[str, Any]:
+    """Parse and fully validate YAML as an initial graph spec."""
+    yaml_text = req.get("yaml_text")
+    if not isinstance(yaml_text, str):
+        return {"ok": False, "error": "validate_spec requires string 'yaml_text'"}
+
+    try:
+        raw = yaml.safe_load(yaml_text)
+    except Exception as exc:
+        return {"ok": False, "error": f"yaml parse failed: {exc}", "traceback": traceback.format_exc()}
+
+    if raw is None:
+        return {"ok": False, "error": "YAML is empty"}
+    if not isinstance(raw, dict):
+        return {"ok": False, "error": f"expected mapping, got {type(raw).__name__}"}
+
+    try:
+        spec = spec_cls.model_validate(raw)
+    except Exception as exc:
+        return {"ok": False, "error": f"spec validation failed: {exc}", "traceback": traceback.format_exc()}
+
+    return {"ok": True, "spec_dict": spec.to_dict()}
+
+
+def main() -> int:
+    return _serve()
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py
new file mode 100644
index 000000000..06ec72547
--- /dev/null
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py
@@ -0,0 +1,156 @@
+# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""JSON-RPC client for the persistent :mod:`isaaclab_arena_examples.agentic_environment_generation.review_gui.simapp_sidecar` process."""
+
+from __future__ import annotations
+
+import contextlib
+import json
+import os
+import subprocess
+import sys
+import threading
+from typing import Any
+
+
+class SimAppSidecarError(RuntimeError):
+    """Raised when the SimApp sidecar process can't fulfil a request."""
+
+
+class SimAppSidecar:
+    """Long-lived Kit/SimApp host process exposed as a validation service.
+
+    See ``simapp_sidecar.py`` for the protocol. Cached via ``@st.cache_resource``
+    in the Streamlit app; pipe access is serialized with an internal lock.
+    """
+
+    def __init__(self, *, boot_timeout_s: float = 180.0, shutdown_timeout_s: float = 10.0) -> None:
+        self._proc: subprocess.Popen | None = None
+        self._lock = threading.Lock()
+        self._boot_timeout_s = boot_timeout_s
+        self._shutdown_timeout_s = shutdown_timeout_s
+
+    def start(self) -> None:
+        """Spawn the sidecar process and wait for its ``{"ready": true}`` handshake."""
+        if self._proc is not None and self._proc.poll() is None:
+            return
+
+        cmd = [
+            sys.executable,
+            "-m",
+            "isaaclab_arena_examples.agentic_environment_generation.review_gui.simapp_sidecar",
+        ]
+        self._proc = subprocess.Popen(
+            cmd,
+            stdin=subprocess.PIPE,
+            stdout=subprocess.PIPE,
+            stderr=None,
+            text=True,
+            bufsize=1,
+            env=os.environ.copy(),
+        )
+
+        line = self._readline_or_die()
+        try:
+            msg = json.loads(line)
+        except json.JSONDecodeError as exc:
+            self._terminate()
+            raise SimAppSidecarError(f"Sidecar emitted non-JSON handshake: {line!r}") from exc
+
+        if not msg.get("ready"):
+            self._terminate()
+            raise SimAppSidecarError(
+                f"Sidecar boot failed: {msg.get('error', 'unknown error')}\n{msg.get('traceback', '')}"
+            )
+
+    def is_alive(self) -> bool:
+        return self._proc is not None and self._proc.poll() is None
+
+    def close(self) -> None:
+        """Send ``shutdown``, then terminate/kill if the process doesn't exit."""
+        proc = self._proc
+        if proc is None:
+            return
+        self._proc = None
+
+        if proc.poll() is None:
+            with contextlib.suppress(Exception):
+                proc.stdin.write(json.dumps({"cmd": "shutdown"}) + "\n")
+                proc.stdin.flush()
+            try:
+                proc.wait(timeout=self._shutdown_timeout_s)
+            except subprocess.TimeoutExpired:
+                proc.terminate()
+                try:
+                    proc.wait(timeout=5)
+                except subprocess.TimeoutExpired:
+                    proc.kill()
+                    with contextlib.suppress(Exception):
+                        proc.wait(timeout=5)
+
+        with contextlib.suppress(Exception):
+            if proc.stdin:
+                proc.stdin.close()
+        with contextlib.suppress(Exception):
+            if proc.stdout:
+                proc.stdout.close()
+
+    def validate_yaml_text(self, yaml_text: str) -> dict[str, Any]:
+        """Run full spec validation (including registry lookups) in the sidecar."""
+        if not self.is_alive():
+            raise SimAppSidecarError("SimApp sidecar is not running — start it first")
+
+        with self._lock:
+            return self._request({"cmd": "validate_spec", "yaml_text": yaml_text})
+
+    def ping(self) -> bool:
+        """Cheap liveness check round-trip — returns True on a healthy reply."""
+        if not self.is_alive():
+            return False
+        with self._lock:
+            try:
+                response = self._request({"cmd": "ping"})
+            except SimAppSidecarError:
+                return False
+        return bool(response.get("ok"))
+
+    def _request(self, payload: dict[str, Any]) -> dict[str, Any]:
+        assert self._proc is not None and self._proc.stdin is not None and self._proc.stdout is not None
+        line = json.dumps(payload) + "\n"
+        try:
+            self._proc.stdin.write(line)
+            self._proc.stdin.flush()
+        except BrokenPipeError as exc:
+            raise SimAppSidecarError("sidecar pipe closed unexpectedly") from exc
+
+        reply_line = self._readline_or_die()
+        try:
+            return json.loads(reply_line)
+        except json.JSONDecodeError as exc:
+            raise SimAppSidecarError(f"sidecar replied with non-JSON: {reply_line!r}") from exc
+
+    def _readline_or_die(self) -> str:
+        assert self._proc is not None and self._proc.stdout is not None
+        line = self._proc.stdout.readline()
+        if line == "":
+            exit_code = self._proc.poll()
+            raise SimAppSidecarError(
+                f"sidecar exited prematurely (exit code: {exit_code}). "
+                "See its stderr output above for the underlying cause."
+            )
+        return line
+
+    def _terminate(self) -> None:
+        if self._proc is None:
+            return
+        with contextlib.suppress(Exception):
+            self._proc.terminate()
+        try:
+            self._proc.wait(timeout=5)
+        except subprocess.TimeoutExpired:
+            with contextlib.suppress(Exception):
+                self._proc.kill()
+        self._proc = None
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
index cbbab13ee..7ce2996eb 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
@@ -9,25 +9,34 @@
 
     /isaac-sim/python.sh -m isaaclab_arena_examples.agentic_environment_generation.review_gui.server \\
         --yaml isaaclab_arena/tests/test_data/pick_and_place_maple_table_init_env_graph.yaml
+
+Registry lookups (task kinds, relation kinds) run in a persistent SimApp
+sidecar so YAML re-validation stays fast after the first ~30s sidecar boot.
 """
 
 from __future__ import annotations
 
 import argparse
+import atexit
 import traceback
 import yaml
 from dataclasses import dataclass
 from pathlib import Path
+from typing import Any
 
 import streamlit as st
 
 from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
 from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.dashboard import render_dashboard_html
+from isaaclab_arena_examples.agentic_environment_generation.review_gui.simapp_sidecar_client import (
+    SimAppSidecar,
+    SimAppSidecarError,
+)
 
-# Visualization iframe height. Tuned so the graph + tasks + node grid all
-# fit without an outer Streamlit scrollbar swallowing the inner one.
 _IFRAME_HEIGHT_PX = 1100
 
+_SKIP_REGISTRY_CONTEXT: dict[str, Any] = {"skip_registry": True}
+
 _BROKEN_PLACEHOLDER_HTML = """<!DOCTYPE html><html><body style="
     font-family: ui-monospace, monospace;
     background:#15181d; color:#e4e6eb; padding:24px; margin:0;">
@@ -35,6 +44,36 @@
 </body></html>"""
 
 
+@st.cache_resource(show_spinner="Booting Isaac Sim sidecar (≈30s first run, cached afterwards)…")
+def _get_simapp_sidecar() -> SimAppSidecar | None:
+    """Spawn the SimApp sidecar once per Streamlit server process."""
+    sidecar = SimAppSidecar()
+    try:
+        sidecar.start()
+    except SimAppSidecarError as exc:
+        print(f"[review_gui] SimApp sidecar failed to start: {exc}", flush=True)
+        return None
+
+    atexit.register(sidecar.close)
+    return sidecar
+
+
+def _ensure_sidecar() -> SimAppSidecar | None:
+    """Return a healthy sidecar, re-spawning if the cached one died."""
+    sidecar = _get_simapp_sidecar()
+    if sidecar is not None and sidecar.is_alive():
+        return sidecar
+    if sidecar is not None:
+        sidecar.close()
+    _get_simapp_sidecar.clear()
+    return _get_simapp_sidecar()
+
+
+def _spec_from_sidecar_dict(spec_dict: dict[str, Any]) -> ArenaEnvInitialGraphSpec:
+    """Rebuild a validated spec locally without registry imports."""
+    return ArenaEnvInitialGraphSpec.model_validate(spec_dict, context=_SKIP_REGISTRY_CONTEXT)
+
+
 @dataclass
 class ValidationResult:
     """Outcome of parsing and validating YAML text as an initial graph spec."""
@@ -48,14 +87,46 @@ def is_valid(self) -> bool:
 
 
 def validate_yaml_text(text: str) -> ValidationResult:
-    """Parse ``text`` as YAML and validate it as an :class:`ArenaEnvInitialGraphSpec`."""
+    """Parse YAML and validate via the SimApp sidecar (registry lookups run there)."""
     try:
         raw = yaml.safe_load(text)
-        spec = ArenaEnvInitialGraphSpec.model_validate(raw)
-        return ValidationResult(spec=spec, error=None)
     except Exception:
         return ValidationResult(spec=None, error=traceback.format_exc())
 
+    if raw is None:
+        return ValidationResult(spec=None, error="YAML is empty")
+    if not isinstance(raw, dict):
+        return ValidationResult(spec=None, error=f"Expected mapping, got {type(raw).__name__}")
+
+    sidecar = _ensure_sidecar()
+    if sidecar is None:
+        return ValidationResult(
+            spec=None,
+            error=(
+                "SimApp sidecar is unavailable — cannot validate registry entries. "
+                "Check the terminal where you launched the server."
+            ),
+        )
+
+    try:
+        response = sidecar.validate_yaml_text(text)
+    except SimAppSidecarError as exc:
+        _get_simapp_sidecar.clear()
+        return ValidationResult(spec=None, error=str(exc))
+
+    if not response.get("ok"):
+        err = response.get("error", "validation failed")
+        tb = response.get("traceback", "")
+        message = f"{err}\n\n{tb}" if tb else str(err)
+        return ValidationResult(spec=None, error=message)
+
+    try:
+        spec = _spec_from_sidecar_dict(response["spec_dict"])
+    except Exception:
+        return ValidationResult(spec=None, error=traceback.format_exc())
+
+    return ValidationResult(spec=spec, error=None)
+
 
 def parse_args() -> argparse.Namespace:
     parser = argparse.ArgumentParser(description=__doc__)
@@ -208,5 +279,4 @@ def main() -> None:
         render_visualization_panel()
 
 
-# Streamlit invokes the script top-level on every rerun.
 main()

From 56b912785b96b85511e681e89c684aaa4b1cea92 Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Mon, 15 Jun 2026 08:27:50 -0700
Subject: [PATCH 08/19] Add live USD snapshot rendering to the review GUI
 sidecar.

Render node thumbnails via Kit viewport capture in the sidecar, wire
render_spec through the client, and inline PNGs in the dashboard.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../review_gui/render/dashboard.py            |   5 +-
 .../review_gui/render/panels.py               |  13 +-
 .../review_gui/render/thumbnails.py           |  14 +-
 .../review_gui/simapp_sidecar.py              |  86 +++--
 .../review_gui/simapp_sidecar_client.py       |  38 +-
 .../review_gui/streamlit_ui.py                |  34 +-
 .../review_gui/thumbnail_render.py            | 356 ++++++++++++++++++
 7 files changed, 499 insertions(+), 47 deletions(-)
 create mode 100644 isaaclab_arena_examples/agentic_environment_generation/review_gui/thumbnail_render.py

diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/dashboard.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/dashboard.py
index a4318c3d3..731b3b781 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/dashboard.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/dashboard.py
@@ -17,9 +17,10 @@
 from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.styles import DASHBOARD_CSS
 
 
-def render_dashboard_html(spec: ArenaEnvInitialGraphSpec) -> str:
+def render_dashboard_html(spec: ArenaEnvInitialGraphSpec, thumbnails: dict[str, bytes] | None = None) -> str:
     """Render the self-contained review dashboard HTML for ``spec``."""
     initial_state = spec.initial_state_spec
+    thumbnails = thumbnails or {}
     return f"""<!DOCTYPE html>
 <html lang="en">
 <head>
@@ -45,7 +46,7 @@ def render_dashboard_html(spec: ArenaEnvInitialGraphSpec) -> str:
   </section>
   <section class="panel nodes-panel">
     <h2>Nodes</h2>
-    <div class="node-grid">{render_node_cards(spec)}</div>
+    <div class="node-grid">{render_node_cards(spec, thumbnails)}</div>
   </section>
 </main>
 <script>mermaid.initialize({{ startOnLoad: true, theme: 'dark', themeVariables: {{ fontFamily: 'ui-monospace, monospace' }} }});</script>
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/panels.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/panels.py
index 901b4c331..1f3675b69 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/panels.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/panels.py
@@ -10,9 +10,7 @@
 
 from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
 from isaaclab_arena.environments.arena_env_graph_types import ArenaEnvGraphNodeSpec, ArenaEnvGraphStateSpec
-from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.thumbnails import (
-    render_placeholder_thumbnail,
-)
+from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.thumbnails import render_node_thumbnail
 
 
 def render_unary_constraints(state: ArenaEnvGraphStateSpec) -> str:
@@ -62,14 +60,15 @@ def render_tasks_table(spec: ArenaEnvInitialGraphSpec) -> str:
     )
 
 
-def render_node_cards(spec: ArenaEnvInitialGraphSpec) -> str:
-    return "\n".join(render_node_card(node) for node in spec.nodes)
+def render_node_cards(spec: ArenaEnvInitialGraphSpec, thumbnails: dict[str, bytes] | None = None) -> str:
+    thumbnails = thumbnails or {}
+    return "\n".join(render_node_card(node, thumbnails.get(node.id)) for node in spec.nodes)
 
 
-def render_node_card(node: ArenaEnvGraphNodeSpec) -> str:
+def render_node_card(node: ArenaEnvGraphNodeSpec, png_bytes: bytes | None = None) -> str:
     node_dict = node.model_dump(mode="json", exclude_none=True)
     node_yaml = yaml.safe_dump(node_dict, sort_keys=False).rstrip()
-    thumb = render_placeholder_thumbnail(node)
+    thumb = render_node_thumbnail(node, png_bytes)
     return f"""<article class="node-card type-{html_lib.escape(node.type.value)}">
   {thumb}
   <div class="node-meta">
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/thumbnails.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/thumbnails.py
index f2742ee8f..4b2a5eb23 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/thumbnails.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/thumbnails.py
@@ -5,14 +5,22 @@
 
 from __future__ import annotations
 
+import base64
 import html as html_lib
 
 from isaaclab_arena.environments.arena_env_graph_types import ArenaEnvGraphNodeSpec
 
 
-# TODO(qianl): Replace placeholder thumbnails with sim-rendered snapshots .
-def render_placeholder_thumbnail(node: ArenaEnvGraphNodeSpec) -> str:
-    """Per-node placeholder thumbnail — two-letter initial."""
+def render_node_thumbnail(node: ArenaEnvGraphNodeSpec, png_bytes: bytes | None = None) -> str:
+    """Per-node thumbnail: USD capture if available, else two-letter placeholder."""
+    if png_bytes:
+        b64 = base64.b64encode(png_bytes).decode("ascii")
+        return (
+            '<div class="thumb thumb-rendered">'
+            f'<img src="data:image/png;base64,{b64}" alt="{html_lib.escape(node.name)} thumbnail">'
+            f'<span class="thumb-name">{html_lib.escape(node.name)}</span>'
+            "</div>"
+        )
     initial = (node.name[:2] if node.name else "?").upper()
     return f"""<div class="thumb">
     <span class="thumb-initial">{html_lib.escape(initial)}</span>
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
index ee107cc75..95045d69c 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
@@ -6,9 +6,10 @@
 """Long-lived ``SimulationApp`` host process for the live review editor.
 
 Boots Kit's ``SimulationApp`` once on *its own* main thread and serves
-spec-validation requests over a newline-delimited JSON-RPC pipe on
-stdin/stdout. The parent (``streamlit_ui.py`` running inside Streamlit) spawns
-exactly one of these and reuses it for the entire server lifetime via
+validation and thumbnail-render requests over a newline-delimited JSON-RPC
+pipe on stdin/stdout. The parent (``streamlit_ui.py`` running inside
+Streamlit) spawns exactly one of these and reuses it for the entire server
+lifetime via
 :class:`isaaclab_arena_examples.agentic_environment_generation.review_gui.simapp_sidecar_client.SimAppSidecar`.
 
 Why a sidecar and not an in-process ``SimulationApp``:
@@ -16,8 +17,10 @@
 * ``signal.signal`` only works in the main thread. Streamlit's
   ``ScriptRunner`` runs the script in a worker thread, so SimApp's signal
   setup raises ``ValueError("signal only works in main thread …")``.
-* Registry imports transitively load ``pxr``, which must happen only after
-  ``SimulationApp`` starts. A dedicated process keeps that ordering safe.
+* ``omni.usd.UsdContext`` is process-singleton AND can't tolerate cross-
+  thread driving from Streamlit reruns — driving it from worker threads
+  triggers ``[Error] [omni.usd] UsdContext busy`` and the open_stage call
+  fails. A dedicated process with serialized request handling avoids both.
 
 Protocol (newline-delimited JSON over stdin/stdout):
 
@@ -34,6 +37,12 @@
         (full :class:`ArenaEnvInitialGraphSpec` validation including registry
          lookups — runs in the sidecar where registries are already warm)
 
+    {"cmd": "render_spec", "yaml_text": "..."}
+      → {"ok": true, "paths": {"node_id": "/abs/path/to.png", ...},
+                       "errors": [{"node_id": "...", "error": "..."}]}
+        (paths are absolute filesystem paths on the disk cache. The PNGs
+         themselves stay on disk — the parent reads them itself.)
+
     {"cmd": "shutdown"}
       → {"ok": true}   # sidecar exits cleanly after replying
 
@@ -51,7 +60,6 @@
 
 from __future__ import annotations
 
-import argparse
 import contextlib
 import json
 import os
@@ -59,15 +67,10 @@
 import sys
 import traceback
 import yaml
+from pathlib import Path
 from typing import Any
 
-# ---------------------------------------------------------------------------
-# stdout multiplexing setup — run BEFORE importing anything that might
-# touch Kit or print to stdout, otherwise Kit's chatter pollutes the JSON
-# channel and the parent crashes on the first bad json.loads.
-# ---------------------------------------------------------------------------
-
-_JSON_FD = os.dup(1)  # save real stdout for our JSON channel
+_JSON_FD = os.dup(1)
 os.dup2(2, 1)
 sys.stdout = sys.stderr
 
@@ -78,18 +81,6 @@ def _send(payload: dict[str, Any]) -> None:
     os.write(_JSON_FD, data)
 
 
-def _launch_simulation_app():
-    """Boot Isaac Sim's ``SimulationApp`` for registry-backed validation."""
-    try:
-        from isaaclab_arena.utils.isaaclab_utils.simulation_app import get_app_launcher  # noqa: PLC0415
-
-        sim_args = argparse.Namespace(headless=True, enable_cameras=False, hide_ui=True, livestream=-1)
-        return get_app_launcher(sim_args).app
-    except Exception as exc:
-        print(f"[simapp_sidecar] SimulationApp launch failed: {exc}", file=sys.stderr)
-        return None
-
-
 def _install_signal_handlers() -> None:
     def _exit(signum, _frame):
         raise SystemExit(0)
@@ -99,15 +90,26 @@ def _exit(signum, _frame):
 
 
 def _serve() -> int:
-    """Boot SimApp, hand-shake with the parent, then service validation requests."""
+    """Boot SimApp, hand-shake with the parent, then service requests."""
     _install_signal_handlers()
 
+    try:
+        from isaaclab_arena_examples.agentic_environment_generation.review_gui.thumbnail_render import (  # noqa: PLC0415
+            _launch_simulation_app,
+        )
+    except Exception as exc:
+        _send({"ready": False, "error": f"import failed: {exc}", "traceback": traceback.format_exc()})
+        return 1
+
     app = _launch_simulation_app()
     if app is None:
         _send({"ready": False, "error": "SimulationApp launch returned None"})
         return 1
 
     from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec  # noqa: PLC0415
+    from isaaclab_arena_examples.agentic_environment_generation.review_gui.thumbnail_render import (  # noqa: PLC0415
+        _render_thumbnails_with_app,
+    )
 
     _send({"ready": True})
 
@@ -135,6 +137,10 @@ def _serve() -> int:
                 _send(_handle_validate_spec(req, ArenaEnvInitialGraphSpec))
                 continue
 
+            if cmd == "render_spec":
+                _send(_handle_render_spec(app, req, _render_thumbnails_with_app, ArenaEnvInitialGraphSpec))
+                continue
+
             _send({"ok": False, "error": f"unknown cmd: {cmd!r}"})
 
         return 0
@@ -167,6 +173,34 @@ def _handle_validate_spec(req: dict[str, Any], spec_cls) -> dict[str, Any]:
     return {"ok": True, "spec_dict": spec.to_dict()}
 
 
+def _handle_render_spec(
+    app,
+    req: dict[str, Any],
+    render_fn,
+    spec_cls,
+) -> dict[str, Any]:
+    """Parse the spec, run thumbnail rendering, marshal the response."""
+    yaml_text = req.get("yaml_text")
+    if not isinstance(yaml_text, str):
+        return {"ok": False, "error": "render_spec requires string 'yaml_text'"}
+
+    try:
+        spec = spec_cls.from_dict(yaml.safe_load(yaml_text))
+    except Exception as exc:
+        return {"ok": False, "error": f"spec parse failed: {exc}", "traceback": traceback.format_exc()}
+
+    try:
+        paths: dict[str, Path] = render_fn(app, spec)
+    except Exception as exc:
+        return {"ok": False, "error": f"render failed: {exc}", "traceback": traceback.format_exc()}
+
+    return {
+        "ok": True,
+        "paths": {node_id: str(p) for node_id, p in paths.items()},
+        "errors": [],
+    }
+
+
 def main() -> int:
     return _serve()
 
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py
index 06ec72547..546921e3b 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py
@@ -13,19 +13,19 @@
 import subprocess
 import sys
 import threading
+import yaml
+from pathlib import Path
 from typing import Any
 
+from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
+
 
 class SimAppSidecarError(RuntimeError):
     """Raised when the SimApp sidecar process can't fulfil a request."""
 
 
 class SimAppSidecar:
-    """Long-lived Kit/SimApp host process exposed as a validation service.
-
-    See ``simapp_sidecar.py`` for the protocol. Cached via ``@st.cache_resource``
-    in the Streamlit app; pipe access is serialized with an internal lock.
-    """
+    """Long-lived Kit/SimApp host process exposed as a validation and render service."""
 
     def __init__(self, *, boot_timeout_s: float = 180.0, shutdown_timeout_s: float = 10.0) -> None:
         self._proc: subprocess.Popen | None = None
@@ -106,6 +106,34 @@ def validate_yaml_text(self, yaml_text: str) -> dict[str, Any]:
         with self._lock:
             return self._request({"cmd": "validate_spec", "yaml_text": yaml_text})
 
+    def render_spec(self, spec: ArenaEnvInitialGraphSpec) -> dict[str, bytes]:
+        """Ask the sidecar to render thumbnails for ``spec``."""
+        if not self.is_alive():
+            raise SimAppSidecarError("SimApp sidecar is not running — start it first")
+
+        yaml_text = yaml.safe_dump(spec.to_dict(), sort_keys=False)
+
+        with self._lock:
+            response = self._request({"cmd": "render_spec", "yaml_text": yaml_text})
+
+        if not response.get("ok"):
+            raise SimAppSidecarError(
+                f"sidecar render failed: {response.get('error', 'unknown')}\n{response.get('traceback', '')}"
+            )
+
+        paths: dict[str, str] = response.get("paths", {}) or {}
+        results: dict[str, bytes] = {}
+        for node_id, path_str in paths.items():
+            path = Path(path_str)
+            if path.exists() and path.stat().st_size > 0:
+                results[node_id] = path.read_bytes()
+            else:
+                print(
+                    f"[review_gui]   sidecar reported {node_id} -> {path_str} but file is missing.",
+                    file=sys.stderr,
+                )
+        return results
+
     def ping(self) -> bool:
         """Cheap liveness check round-trip — returns True on a healthy reply."""
         if not self.is_alive():
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
index 7ce2996eb..7d5b95f89 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
@@ -10,8 +10,9 @@
     /isaac-sim/python.sh -m isaaclab_arena_examples.agentic_environment_generation.review_gui.server \\
         --yaml isaaclab_arena/tests/test_data/pick_and_place_maple_table_init_env_graph.yaml
 
-Registry lookups (task kinds, relation kinds) run in a persistent SimApp
-sidecar so YAML re-validation stays fast after the first ~30s sidecar boot.
+Registry lookups (task kinds, relation kinds, asset USD paths) run in a
+persistent SimApp sidecar so YAML re-validation stays fast after the first
+~30s sidecar boot. Thumbnails are rendered live by the same sidecar.
 """
 
 from __future__ import annotations
@@ -74,6 +75,31 @@ def _spec_from_sidecar_dict(spec_dict: dict[str, Any]) -> ArenaEnvInitialGraphSp
     return ArenaEnvInitialGraphSpec.model_validate(spec_dict, context=_SKIP_REGISTRY_CONTEXT)
 
 
+def _render_with_thumbnails(spec: ArenaEnvInitialGraphSpec) -> str:
+    """Render review HTML, asking the sidecar for live USD thumbnails."""
+    sidecar = _ensure_sidecar()
+    if sidecar is None:
+        st.warning(
+            "Isaac Sim sidecar is unavailable — showing placeholder thumbnails. "
+            "Check the terminal where you launched the server for the underlying error.",
+            icon="⚠️",
+        )
+        return render_dashboard_html(spec)
+
+    try:
+        thumbnails = sidecar.render_spec(spec)
+    except SimAppSidecarError as exc:
+        st.error(
+            f"Sidecar render failed; showing placeholder thumbnails.\n\n```\n{exc}\n```",
+            icon="🛑",
+        )
+        with st.spinner("Resetting the SimApp sidecar…"):
+            _get_simapp_sidecar.clear()
+        return render_dashboard_html(spec)
+
+    return render_dashboard_html(spec, thumbnails=thumbnails if thumbnails else None)
+
+
 @dataclass
 class ValidationResult:
     """Outcome of parsing and validating YAML text as an initial graph spec."""
@@ -156,7 +182,7 @@ def initialize_state(yaml_path: Path) -> None:
     if not initial.is_valid:
         st.session_state["rendered_html"] = _BROKEN_PLACEHOLDER_HTML
     else:
-        st.session_state["rendered_html"] = render_dashboard_html(initial.spec)
+        st.session_state["rendered_html"] = _render_with_thumbnails(initial.spec)
 
 
 def render_validation_badge(validation: ValidationResult) -> None:
@@ -237,7 +263,7 @@ def render_editor_panel(yaml_path: Path) -> ValidationResult:
     edited_since_render = st.session_state["edited_text"] != st.session_state["last_rendered_text"]
     if validation.is_valid and edited_since_render:
         with st.spinner("Rendering visualization…"):
-            st.session_state["rendered_html"] = render_dashboard_html(validation.spec)
+            st.session_state["rendered_html"] = _render_with_thumbnails(validation.spec)
         st.session_state["last_rendered_text"] = st.session_state["edited_text"]
         st.toast("Visualization updated.", icon="🔄")
 
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/thumbnail_render.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/thumbnail_render.py
new file mode 100644
index 000000000..d4ea06a9b
--- /dev/null
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/thumbnail_render.py
@@ -0,0 +1,356 @@
+# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""USD viewport thumbnail rendering for the review GUI SimApp sidecar."""
+
+from __future__ import annotations
+
+import argparse
+import hashlib
+import sys
+from pathlib import Path
+
+from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
+
+THUMBNAIL_CACHE_DIR = Path(__file__).resolve().parents[3] / ".cache" / "llm_env_gen_thumbnails"
+
+
+def _render_thumbnails_with_app(app, spec: ArenaEnvInitialGraphSpec) -> dict[str, Path]:
+    """Resolve each node's USD via ``AssetRegistry``, render cache-misses, return PNG paths.
+
+    ``app`` must already be a booted ``SimulationApp``. The caller owns the
+    lifecycle (Kit may turn ``app.close()`` into ``os._exit(0)`` — that's why
+    the sidecar holds the only reference and closes it inside its ``finally``).
+
+    Returns ``{node.id: png_path}`` for nodes whose asset USD could be located
+    *and* whose PNG exists on disk (either from the persistent cache under
+    ``THUMBNAIL_CACHE_DIR`` or freshly rendered into the cache by
+    :func:`_capture_usd_thumbnails`). Missing entries fall through to the
+    placeholder in :func:`_render_node_thumbnail`, so a partial failure (one
+    bad asset) never breaks the rest of the page.
+
+    We return ``Path`` rather than ``bytes`` so the sidecar protocol can ship
+    just the filenames over its stdin/stdout pipe (a few hundred bytes of JSON
+    instead of multiple MB of base64 PNG data). The parent reads the bytes
+    itself off the shared filesystem cache.
+
+    Ordering matters: ``SimulationApp`` MUST be launched before any
+    ``AssetRegistry`` access, because ``ensure_assets_registered()`` imports
+    isaaclab asset modules which transitively load ``pxr``. ``pxr`` loaded
+    before ``AppLauncher`` puts Kit's extension manager into an unrecoverable
+    state ("extension class wrapper for base class ... has not been created
+    yet"). This is the same root cause we fixed for the pytest suite.
+    """
+    asset_paths = _resolve_node_usd_paths(spec)
+    if not asset_paths:
+        print("[thumbnail_render] no asset USD paths resolved; skipping thumbnail rendering.", file=sys.stderr)
+        return {}
+
+    THUMBNAIL_CACHE_DIR.mkdir(parents=True, exist_ok=True)
+
+    # Split into cache-hits vs to-render. Cache key is sha1(usd_path) so
+    # the same USD across multiple envs / nodes hits the same PNG.
+    resolved: dict[str, Path] = {}
+    to_render: dict[str, tuple[str, Path]] = {}
+    for node_id, usd_path in asset_paths.items():
+        cache_path = THUMBNAIL_CACHE_DIR / f"{_usd_cache_key(usd_path)}.png"
+        if cache_path.exists() and cache_path.stat().st_size > 0:
+            resolved[node_id] = cache_path
+        else:
+            to_render[node_id] = (usd_path, cache_path)
+
+    if to_render:
+        print(
+            f"[thumbnail_render] rendering {len(to_render)} new thumbnail(s) "
+            f"(reusing {len(resolved)} from cache at {THUMBNAIL_CACHE_DIR})...",
+            file=sys.stderr,
+        )
+        # ``_capture_usd_thumbnails`` still returns ``{node_id: bytes}``, but
+        # we only use it as a presence signal here — the same call also wrote
+        # the PNG to ``cache_path`` as a side effect, which is what we return.
+        captured = _capture_usd_thumbnails(app, to_render)
+        for node_id, (_usd_path, cache_path) in to_render.items():
+            if node_id in captured and cache_path.exists() and cache_path.stat().st_size > 0:
+                resolved[node_id] = cache_path
+    else:
+        print(f"[thumbnail_render] all {len(resolved)} thumbnail(s) served from cache.", file=sys.stderr)
+
+    return resolved
+
+
+def _launch_simulation_app():
+    """Boot Isaac Sim's ``SimulationApp`` for headless viewport capture, or ``None`` on failure.
+
+    Kept as a tiny helper so the call site can lazy-import inside this
+    function — module-level import of ``simulation_app`` would drag Kit
+    into every invocation, including ``--help``.
+    """
+    try:
+        # Lazy-import: keeps the default ``review_graph`` invocation Kit-free.
+        from isaaclab_arena.utils.isaaclab_utils.simulation_app import get_app_launcher  # noqa: PLC0415
+
+        sim_args = argparse.Namespace(headless=True, enable_cameras=True, hide_ui=True, livestream=-1)
+        return get_app_launcher(sim_args).app
+    except Exception as exc:
+        print(f"[thumbnail_render] SimulationApp launch failed: {exc}", file=sys.stderr)
+        return None
+
+
+def _resolve_node_usd_paths(spec: ArenaEnvInitialGraphSpec) -> dict[str, str]:
+    """Map ``node.id → usd_path`` via :class:`AssetRegistry`, skipping unresolvable nodes.
+
+    Tries two lookup strategies in order:
+
+    1. Class-attribute ``cls.usd_path`` — the convention every ``LibraryObject``
+       subclass in ``object_library.py`` follows. No instantiation, cheap.
+
+    2. ``cls().scene_config.robot.spawn.usd_path`` — the convention every
+       :class:`EmbodimentBase` subclass uses. Requires instantiating the
+       embodiment because the Franka embodiments populate ``scene_config.robot``
+       inside ``__init__`` rather than as a class default. Embodiment
+       ``__init__`` is light (no Kit / sim required) — it only constructs
+       configclass objects.
+
+    This function MUST be called only after ``SimulationApp`` has booted — see
+    the docstring of :func:`_render_thumbnails_with_app` for why.
+    """
+    try:
+        from isaaclab_arena.assets.registries import AssetRegistry  # noqa: PLC0415
+    except Exception as exc:
+        print(f"[thumbnail_render] AssetRegistry import failed: {exc}", file=sys.stderr)
+        return {}
+
+    registry = AssetRegistry()
+    paths: dict[str, str] = {}
+    for node in spec.nodes:
+        try:
+            if not registry.is_registered(node.name):
+                print(f"[thumbnail_render]   {node.id}: asset '{node.name}' not registered, skipping.", file=sys.stderr)
+                continue
+            cls = registry.get_asset_by_name(node.name)
+            usd_path = _extract_usd_path(cls)
+            if not usd_path:
+                print(f"[thumbnail_render]   {node.id}: '{node.name}' has no usd_path, skipping.", file=sys.stderr)
+                continue
+            paths[node.id] = usd_path
+        except Exception as exc:
+            print(f"[thumbnail_render]   {node.id}: lookup failed for '{node.name}': {exc}", file=sys.stderr)
+    return paths
+
+
+def _extract_usd_path(cls) -> str | None:
+    """Return the asset's root USD path, or ``None`` if not extractable.
+
+    See :func:`_resolve_node_usd_paths` for the two strategies tried in order.
+    """
+    # Strategy 1: ``LibraryObject`` convention.
+    usd_path = getattr(cls, "usd_path", None)
+    if usd_path:
+        return usd_path
+
+    # Strategy 2: ``EmbodimentBase`` convention. Walk
+    # ``instance.scene_config.robot.spawn.usd_path``. We instantiate with no
+    # args; every embodiment ``__init__`` defaults all parameters.
+    # NoEmbodiment legitimately has no robot — its instance.scene_config
+    # exists but ``.robot`` is absent / None, so the getattr chain returns
+    # None and we silently fall through.
+    try:
+        instance = cls()
+    except Exception:
+        return None
+    scene_config = getattr(instance, "scene_config", None)
+    robot = getattr(scene_config, "robot", None) if scene_config is not None else None
+    spawn = getattr(robot, "spawn", None) if robot is not None else None
+    return getattr(spawn, "usd_path", None) if spawn is not None else None
+
+
+def _usd_cache_key(usd_path: str) -> str:
+    return hashlib.sha1(usd_path.encode("utf-8")).hexdigest()[:16]
+
+
+def _capture_usd_thumbnails(app, to_render: dict[str, tuple[str, Path]]) -> dict[str, bytes]:
+    """Capture all queued USDs under one already-booted ``SimulationApp``.
+
+    Deduplicates by ``usd_path`` so the same USD shared by multiple nodes is
+    only rendered once and the bytes are fanned back out.
+    """
+    out: dict[str, bytes] = {}
+
+    path_to_node_ids: dict[str, list[str]] = {}
+    path_to_cache: dict[str, Path] = {}
+    for node_id, (usd_path, cache_path) in to_render.items():
+        path_to_node_ids.setdefault(usd_path, []).append(node_id)
+        path_to_cache[usd_path] = cache_path
+
+    for usd_path, node_ids in path_to_node_ids.items():
+        cache_path = path_to_cache[usd_path]
+        try:
+            png_bytes = _render_one_usd(app, usd_path, cache_path)
+        except Exception as exc:
+            print(f"[thumbnail_render]   render failed for {usd_path}: {exc}", file=sys.stderr)
+            continue
+        if png_bytes:
+            for node_id in node_ids:
+                out[node_id] = png_bytes
+
+    return out
+
+
+def _render_one_usd(app, usd_path: str, cache_path: Path) -> bytes | None:
+    """Open ``usd_path`` directly as the stage, frame the camera, capture PNG.
+
+    Opening the USD as the stage root (rather than ``new_stage`` + reference
+    wrapper) is what makes viewport capture actually produce a file in
+    headless mode — Kit's viewport machinery binds to the just-opened stage
+    cleanly, whereas a referenced sub-stage left the render product empty in
+    every test we tried. The trade-off is that we lose isolation between
+    captures (each call replaces the stage), but Kit handles that fine
+    because we call ``open_stage`` again on the next asset.
+    """
+    import omni.usd  # noqa: PLC0415
+    from omni.kit.viewport.utility import (  # noqa: PLC0415
+        capture_viewport_to_file,
+        frame_viewport_prims,
+        get_active_viewport,
+    )
+    from pxr import Sdf  # noqa: PLC0415
+
+    ctx = omni.usd.get_context()
+    if not ctx.open_stage(usd_path):
+        print(f"[thumbnail_render]   open_stage failed: {usd_path}", file=sys.stderr)
+        return None
+    stage = ctx.get_stage()
+
+    # Wait for textures / payloads / Nucleus fetches to settle before framing.
+    _wait_for_stage_load(app, ctx)
+
+    # Standalone object USDs (avocado, bowl, ...) ship no lights, so a viewport
+    # capture renders them as a near-black silhouette against the dark skybox
+    # — that's the "blank thumbnail" symptom. Complete scene USDs (maple table)
+    # already include their own lighting, so this is a no-op for them.
+    _ensure_default_lighting(stage)
+
+    # Use the default prim if present, otherwise the pseudo-root, for framing.
+    target_prim = stage.GetDefaultPrim()
+    if not target_prim or not target_prim.IsValid():
+        target_prim = stage.GetPrimAtPath(Sdf.Path("/"))
+
+    viewport = get_active_viewport()
+
+    # Use Kit's own ``frame_viewport_prims`` (the "F"-key equivalent / ``FramePrimsCommand``)
+    # so we go through the viewport camera controller. Manually editing the
+    # ``/OmniverseKit_Persp`` xform op directly worked sometimes but Kit's
+    # camera controller treats /OmniverseKit_Persp as an internal state and
+    # silently overrode our edits for small assets — that's why avocado / bowl
+    # captured as tiny specks even with the right math. Letting Kit do the
+    # framing is both correct and avoids us re-implementing the math.
+    framed = frame_viewport_prims(viewport, prims=[str(target_prim.GetPath())])
+    if not framed:
+        print(f"[thumbnail_render]   warning: frame_viewport_prims failed for {usd_path}", file=sys.stderr)
+
+    # Settle Hydra after camera change so the captured frame matches the new pose.
+    for _ in range(30):
+        app.update()
+
+    cache_path.parent.mkdir(parents=True, exist_ok=True)
+    capture_obj = capture_viewport_to_file(viewport, str(cache_path))
+
+    _wait_for_capture(app, capture_obj, cache_path, max_updates=600)
+
+    if cache_path.exists() and cache_path.stat().st_size > 0:
+        return cache_path.read_bytes()
+    print(f"[thumbnail_render]   capture produced no file: {cache_path}", file=sys.stderr)
+    return None
+
+
+def _wait_for_stage_load(app, usd_context, max_updates: int = 600) -> None:
+    """Pump frames until ``usd_context.get_stage_loading_status()`` reports nothing pending.
+
+    Returns after stage load completes or after the budget is exhausted. We
+    also need a few extra frames after the count goes to zero so material
+    binding / texture upload finishes — they don't show up in the load count.
+    """
+    settled = 0
+    for _ in range(max_updates):
+        app.update()
+        try:
+            _msg, loading_count, loaded_count = usd_context.get_stage_loading_status()
+        except Exception:
+            return
+        if loading_count == 0 and loaded_count == 0:
+            settled += 1
+            if settled > 15:
+                return
+        else:
+            settled = 0
+
+
+def _wait_for_capture(app, capture_obj, cache_path: Path, max_updates: int = 600) -> None:
+    """Pump ``app.update()`` until the capture PNG lands on disk (or we time out).
+
+    Kit's capture future is fulfilled inside its async loop during
+    ``app.update()``, but future completion doesn't always coincide with the
+    file being flushed — checking the file directly is the most reliable
+    completion signal. We also keep the future-based fast path so a
+    successful capture doesn't have to wait for the file system to settle.
+    """
+    if capture_obj is None:
+        for _ in range(max_updates):
+            app.update()
+        return
+
+    future = (
+        getattr(capture_obj, "_Capture__future", None)
+        or getattr(capture_obj, "_RenderCapture__future", None)
+        or getattr(capture_obj, "future", None)
+    )
+
+    for _ in range(max_updates):
+        app.update()
+        if cache_path.exists() and cache_path.stat().st_size > 0:
+            return
+        if future is not None and future.done():
+            # Future is done but file might still be flushing — give it a few frames.
+            for _ in range(15):
+                app.update()
+                if cache_path.exists() and cache_path.stat().st_size > 0:
+                    return
+            return
+
+
+def _ensure_default_lighting(stage) -> None:
+    """Add a dome + key distant light if the stage has none.
+
+    Without this, standalone object USDs (which don't ship their own lights)
+    render as a near-black silhouette. We skip the addition if any
+    ``UsdLuxLight``-derived prim already exists on the stage to avoid
+    double-lighting scenes like the maple table that bake in their own rig.
+    """
+    from pxr import Gf, Sdf, UsdGeom, UsdLux  # noqa: PLC0415
+
+    for prim in stage.Traverse():
+        if (
+            prim.HasAPI(UsdLux.LightAPI)
+            or prim.IsA(UsdLux.BoundableLightBase)
+            or prim.IsA(UsdLux.NonboundableLightBase)
+        ):
+            return
+
+    # Soft hemispherical fill so the asset is visible from any angle, plus a
+    # weak directional key for shape definition. Intensities are tuned for
+    # OmniPBR / RTX defaults; tweak if asset libraries adopt darker materials.
+    dome = UsdLux.DomeLight.Define(stage, Sdf.Path("/_ReviewDomeLight"))
+    dome.CreateIntensityAttr(800.0)
+    dome.CreateColorAttr(Gf.Vec3f(1.0, 1.0, 1.0))
+
+    key = UsdLux.DistantLight.Define(stage, Sdf.Path("/_ReviewKeyLight"))
+    key.CreateIntensityAttr(2500.0)
+    key.CreateAngleAttr(2.0)
+    # Aim the key roughly from the camera's 3/4 angle so the lit side faces
+    # the viewport.
+    key_xformable = UsdGeom.Xformable(key.GetPrim())
+    key_xformable.ClearXformOpOrder()
+    rot = key_xformable.AddRotateXYZOp()
+    rot.Set(Gf.Vec3f(-45.0, 30.0, 0.0))

From e69503a0445e10c7ae4d9e648882de96f4d314df Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Mon, 15 Jun 2026 09:41:13 -0700
Subject: [PATCH 09/19] Add prompt-driven generation to the review GUI and
 defer pxr on asset import.

Wire LLM fetch plus sidecar catalogue/compile into the live editor with optional
--yaml, and lazy-load USD helpers so library registration avoids early pxr imports.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../environment_generation_agent.py           |  32 +-
 isaaclab_arena/assets/object.py               |  13 +-
 isaaclab_arena/assets/object_library.py       |   2 +-
 .../assets/object_spawn_defaults.py           |  46 +++
 isaaclab_arena/assets/object_utils.py         |  65 ++--
 .../review_gui/server.py                      |  15 +-
 .../review_gui/simapp_sidecar.py              |  76 +++++
 .../review_gui/simapp_sidecar_client.py       |  16 +
 .../review_gui/streamlit_ui.py                | 291 +++++++++++++++++-
 9 files changed, 487 insertions(+), 69 deletions(-)
 create mode 100644 isaaclab_arena/assets/object_spawn_defaults.py

diff --git a/isaaclab_arena/agentic_environment_generation/environment_generation_agent.py b/isaaclab_arena/agentic_environment_generation/environment_generation_agent.py
index b496f0cdc..522b44d53 100644
--- a/isaaclab_arena/agentic_environment_generation/environment_generation_agent.py
+++ b/isaaclab_arena/agentic_environment_generation/environment_generation_agent.py
@@ -250,6 +250,33 @@ def generate_spec(
             A ``(EnvironmentIntentSpec, raw_response)`` tuple. The raw text is
             useful for debugging.
         """
+        data, text = self.fetch_intent_from_prompt(
+            prompt,
+            asset_catalog=asset_catalog,
+            relation_catalog=relation_catalog,
+            task_catalog=task_catalog,
+            temperature=temperature,
+            max_tokens=max_tokens,
+            max_retries=max_retries,
+        )
+        spec = EnvironmentIntentSpec.model_validate(data)
+        return spec, text
+
+    def fetch_intent_from_prompt(
+        self,
+        prompt: str,
+        asset_catalog: AssetCatalogue | None = None,
+        relation_catalog: RelationCatalogue | None = None,
+        task_catalog: TaskCatalogue | None = None,
+        temperature: float = 0.2,
+        max_tokens: int = 4096,
+        max_retries: int = 3,
+    ) -> tuple[dict[str, Any], str]:
+        """Call the model and return parsed intent JSON without registry validation.
+
+        Registry-backed :class:`EnvironmentIntentSpec` validation should run in a
+        SimApp process (e.g. the review GUI sidecar) where registries are warm.
+        """
         asset_catalog = asset_catalog or build_asset_catalogue()
         relation_catalog = relation_catalog or build_relation_catalogue()
         task_catalog = task_catalog or build_task_catalogue()
@@ -268,7 +295,7 @@ def generate_spec(
         last_exc: Exception | None = None
         for attempt in range(1 + max_retries):
             if attempt > 0:
-                print(f"[generate_spec] retry {attempt}/{max_retries} after: {last_exc}", flush=True)
+                print(f"[fetch_intent_from_prompt] retry {attempt}/{max_retries} after: {last_exc}", flush=True)
 
             try:
                 resp = self.client.chat.completions.create(
@@ -299,8 +326,7 @@ def generate_spec(
                 # (e.g. literal tabs) inside JSON strings — DeepSeek-v4-flash is known
                 # to emit these.
                 data = json.loads(text, strict=False)
-                spec = EnvironmentIntentSpec.model_validate(data)
-                return spec, text
+                return data, text
             except Exception as exc:
                 last_exc = exc
 
diff --git a/isaaclab_arena/assets/object.py b/isaaclab_arena/assets/object.py
index e2a92af36..40e9d6089 100644
--- a/isaaclab_arena/assets/object.py
+++ b/isaaclab_arena/assets/object.py
@@ -11,12 +11,9 @@
 from isaaclab.sim.spawners.spawner_cfg import SpawnerCfg
 
 from isaaclab_arena.assets.object_base import ObjectBase, ObjectType
-from isaaclab_arena.assets.object_utils import detect_object_type
 from isaaclab_arena.relations.relations import RelationBase
 from isaaclab_arena.utils.bounding_box import AxisAlignedBoundingBox, quaternion_to_90_deg_z_quarters
 from isaaclab_arena.utils.pose import Pose
-from isaaclab_arena.utils.usd.rigid_bodies import find_shallowest_rigid_body
-from isaaclab_arena.utils.usd_helpers import compute_local_bounding_box_from_usd, has_light, open_stage
 
 
 class Object(ObjectBase):
@@ -49,6 +46,8 @@ def __init__(
                 "object_type is None (indicating auto-detect) but usd_path is also None. usd_path is required to detect"
                 " object type"
             )
+            from isaaclab_arena.assets.object_utils import detect_object_type
+
             object_type = detect_object_type(usd_path=usd_path)
         super().__init__(name=name, prim_path=prim_path, object_type=object_type, **kwargs)
         self.usd_path = usd_path
@@ -69,6 +68,8 @@ def add_relation(self, relation: RelationBase) -> None:
 
     def get_bounding_box(self) -> AxisAlignedBoundingBox:
         """Get local bounding box (relative to object origin)."""
+        from isaaclab_arena.utils.usd_helpers import compute_local_bounding_box_from_usd
+
         assert self.usd_path is not None
         if self.bounding_box is None:
             self.bounding_box = compute_local_bounding_box_from_usd(self.usd_path, self.scale)
@@ -88,6 +89,8 @@ def get_world_bounding_box(self) -> AxisAlignedBoundingBox:
         return local_bbox.rotated_90_around_z(quarters).translated(self.initial_pose.position_xyz)
 
     def get_corners(self, pos: torch.Tensor) -> torch.Tensor:
+        from isaaclab_arena.utils.usd_helpers import compute_local_bounding_box_from_usd
+
         assert self.usd_path is not None
         if self.bounding_box is None:
             self.bounding_box = compute_local_bounding_box_from_usd(self.usd_path, self.scale)
@@ -107,6 +110,8 @@ def enable_reset_pose(self) -> None:
     def get_contact_sensor_cfg(
         self, contact_against_object: ObjectBase | None = None, usd_path: str | None = None
     ) -> ContactSensorCfg:
+        from isaaclab_arena.utils.usd.rigid_bodies import find_shallowest_rigid_body
+
         assert self.object_type == ObjectType.RIGID, "Contact sensor is only supported for rigid objects"
         # We override this function from the parent class because in some assets, the rigid body
         # is not at the root of the USD file. To be robust to this, we find the shallowest rigid body
@@ -177,6 +182,8 @@ def _generate_articulation_cfg(self) -> ArticulationCfg:
         return self._add_initial_pose_to_cfg(object_cfg)
 
     def _generate_base_cfg(self) -> AssetBaseCfg:
+        from isaaclab_arena.utils.usd_helpers import has_light, open_stage
+
         assert self.object_type == ObjectType.BASE
         if self.spawner_cfg is None:
             with open_stage(self.usd_path) as stage:
diff --git a/isaaclab_arena/assets/object_library.py b/isaaclab_arena/assets/object_library.py
index e7bf8c82a..ad565e2ac 100644
--- a/isaaclab_arena/assets/object_library.py
+++ b/isaaclab_arena/assets/object_library.py
@@ -22,7 +22,7 @@
 from isaaclab_arena.assets.lightwheel_lazy import LightwheelLazyPath
 from isaaclab_arena.assets.object import Object
 from isaaclab_arena.assets.object_base import ObjectType
-from isaaclab_arena.assets.object_utils import (
+from isaaclab_arena.assets.object_spawn_defaults import (
     EMPTY_ARTICULATION_INIT_STATE_CFG,
     RIGID_BODY_PROPS_HIGH_PRECISION,
     RIGID_BODY_PROPS_MEDIUM_PRECISION,
diff --git a/isaaclab_arena/assets/object_spawn_defaults.py b/isaaclab_arena/assets/object_spawn_defaults.py
new file mode 100644
index 000000000..4bf52e3f9
--- /dev/null
+++ b/isaaclab_arena/assets/object_spawn_defaults.py
@@ -0,0 +1,46 @@
+# Copyright (c) 2025-2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""Spawn/physics defaults for library objects (no USD / pxr imports)."""
+
+import isaaclab.sim as sim_utils
+from isaaclab.assets import ArticulationCfg
+
+# Predefined rigid body property configurations for assembly tasks
+# High iteration count for precision tasks (peg/hole insertion)
+RIGID_BODY_PROPS_HIGH_PRECISION = sim_utils.RigidBodyPropertiesCfg(
+    disable_gravity=False,
+    max_depenetration_velocity=5.0,
+    linear_damping=0.0,
+    angular_damping=0.0,
+    max_linear_velocity=1000.0,
+    max_angular_velocity=3666.0,
+    enable_gyroscopic_forces=True,
+    solver_position_iteration_count=192,
+    solver_velocity_iteration_count=1,
+    max_contact_impulse=1e32,
+)
+
+# Standard iteration count for gear mesh tasks
+RIGID_BODY_PROPS_MEDIUM_PRECISION = sim_utils.RigidBodyPropertiesCfg(
+    disable_gravity=False,
+    max_depenetration_velocity=5.0,
+    linear_damping=0.0,
+    angular_damping=0.0,
+    max_linear_velocity=1000.0,
+    max_angular_velocity=3666.0,
+    enable_gyroscopic_forces=True,
+    solver_position_iteration_count=32,
+    solver_velocity_iteration_count=32,
+    max_contact_impulse=1e32,
+)
+
+# Initial state configuration for articulations without joints (e.g., rigid bodies treated as articulations).
+# We explicitly set joint_pos and joint_vel to empty dicts to avoid the default pattern {".*": 0.0} in ArticulationCfg.InitialStateCfg,
+# which would fail to match when there are no joints in the articulation.
+EMPTY_ARTICULATION_INIT_STATE_CFG = ArticulationCfg.InitialStateCfg(
+    joint_pos={},
+    joint_vel={},
+)
diff --git a/isaaclab_arena/assets/object_utils.py b/isaaclab_arena/assets/object_utils.py
index 0b0d2c289..84445f794 100644
--- a/isaaclab_arena/assets/object_utils.py
+++ b/isaaclab_arena/assets/object_utils.py
@@ -4,15 +4,28 @@
 # SPDX-License-Identifier: Apache-2.0
 
 
-import isaaclab.sim as sim_utils
-from isaaclab.assets import ArticulationCfg
-from pxr import Usd
+from typing import TYPE_CHECKING
 
 from isaaclab_arena.assets.object_base import ObjectType
-from isaaclab_arena.utils.usd_helpers import get_prim_depth, is_articulation_root, is_rigid_body
+from isaaclab_arena.assets.object_spawn_defaults import (
+    EMPTY_ARTICULATION_INIT_STATE_CFG,
+    RIGID_BODY_PROPS_HIGH_PRECISION,
+    RIGID_BODY_PROPS_MEDIUM_PRECISION,
+)
+
+if TYPE_CHECKING:
+    from pxr import Usd
+
+# Re-export spawn defaults for backward compatibility.
+__all__ = [
+    "EMPTY_ARTICULATION_INIT_STATE_CFG",
+    "RIGID_BODY_PROPS_HIGH_PRECISION",
+    "RIGID_BODY_PROPS_MEDIUM_PRECISION",
+    "detect_object_type",
+]
 
 
-def detect_object_type(usd_path: str | None = None, stage: Usd.Stage | None = None) -> ObjectType:
+def detect_object_type(usd_path: str | None = None, stage: "Usd.Stage | None" = None) -> ObjectType:
     """Detect the object type of the asset
 
     Goes through the USD tree and detects the object type. The detection is based
@@ -28,6 +41,10 @@ def detect_object_type(usd_path: str | None = None, stage: Usd.Stage | None = No
     Returns:
         The object type of the asset.
     """
+    from pxr import Usd
+
+    from isaaclab_arena.utils.usd_helpers import get_prim_depth, is_articulation_root, is_rigid_body
+
     assert usd_path is not None or stage is not None, "Either usd_path or stage must be provided"
     assert usd_path is None or stage is None, "Either usd_path or stage must be provided"
     if usd_path is not None:
@@ -62,41 +79,3 @@ def detect_object_type(usd_path: str | None = None, stage: Usd.Stage | None = No
         return ObjectType.ARTICULATION
     else:
         raise ValueError("This should not happen. There is an unknown USD type in the tree.")
-
-
-# Predefined rigid body property configurations for assembly tasks
-# High iteration count for precision tasks (peg/hole insertion)
-RIGID_BODY_PROPS_HIGH_PRECISION = sim_utils.RigidBodyPropertiesCfg(
-    disable_gravity=False,
-    max_depenetration_velocity=5.0,
-    linear_damping=0.0,
-    angular_damping=0.0,
-    max_linear_velocity=1000.0,
-    max_angular_velocity=3666.0,
-    enable_gyroscopic_forces=True,
-    solver_position_iteration_count=192,
-    solver_velocity_iteration_count=1,
-    max_contact_impulse=1e32,
-)
-
-# Standard iteration count for gear mesh tasks
-RIGID_BODY_PROPS_MEDIUM_PRECISION = sim_utils.RigidBodyPropertiesCfg(
-    disable_gravity=False,
-    max_depenetration_velocity=5.0,
-    linear_damping=0.0,
-    angular_damping=0.0,
-    max_linear_velocity=1000.0,
-    max_angular_velocity=3666.0,
-    enable_gyroscopic_forces=True,
-    solver_position_iteration_count=32,
-    solver_velocity_iteration_count=32,
-    max_contact_impulse=1e32,
-)
-
-# Initial state configuration for articulations without joints (e.g., rigid bodies treated as articulations).
-# We explicitly set joint_pos and joint_vel to empty dicts to avoid the default pattern {".*": 0.0} in ArticulationCfg.InitialStateCfg,
-# which would fail to match when there are no joints in the articulation.
-EMPTY_ARTICULATION_INIT_STATE_CFG = ArticulationCfg.InitialStateCfg(
-    joint_pos={},
-    joint_vel={},
-)
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/server.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/server.py
index 4212cf6a7..92b0fa58f 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/server.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/server.py
@@ -11,6 +11,9 @@
     /isaac-sim/python.sh -m isaaclab_arena_examples.agentic_environment_generation.review_gui.server \\
         --yaml isaaclab_arena/tests/test_data/pick_and_place_maple_table_init_env_graph.yaml
 
+    # Prompt-only (empty editor until you generate or paste YAML):
+    /isaac-sim/python.sh -m isaaclab_arena_examples.agentic_environment_generation.review_gui.server
+
     # Custom port:
     /isaac-sim/python.sh -m isaaclab_arena_examples.agentic_environment_generation.review_gui.server \\
         --yaml <path> --port 8600
@@ -33,8 +36,8 @@ def main() -> None:
     parser.add_argument(
         "--yaml",
         type=Path,
-        required=True,
-        help="Path to an ArenaEnvInitialGraphSpec YAML file.",
+        default=None,
+        help="Optional ArenaEnvInitialGraphSpec YAML to open in the editor.",
     )
     parser.add_argument(
         "--port",
@@ -46,8 +49,8 @@ def main() -> None:
     serve_live_editor(args.yaml, port=args.port)
 
 
-def serve_live_editor(yaml_path: Path, port: int = 8501) -> None:
-    """Spawn ``streamlit run streamlit_ui.py -- --yaml <path>`` and wait."""
+def serve_live_editor(yaml_path: Path | None, port: int = 8501) -> None:
+    """Spawn ``streamlit run streamlit_ui.py`` and wait."""
     app_path = Path(__file__).with_name("streamlit_ui.py")
     if not app_path.exists():
         raise FileNotFoundError(f"Streamlit app not found at {app_path} — installation is incomplete.")
@@ -65,9 +68,9 @@ def serve_live_editor(yaml_path: Path, port: int = 8501) -> None:
         "--server.fileWatcherType",
         "none",
         "--",
-        "--yaml",
-        str(yaml_path.resolve()),
     ]
+    if yaml_path is not None:
+        cmd.extend(["--yaml", str(yaml_path.resolve())])
 
     print(f"[review_gui] launching Streamlit live editor: {' '.join(cmd)}", file=sys.stderr)
     try:
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
index 95045d69c..5d40a8f05 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
@@ -43,6 +43,16 @@
         (paths are absolute filesystem paths on the disk cache. The PNGs
          themselves stay on disk — the parent reads them itself.)
 
+    {"cmd": "build_catalogues"}
+      → {"ok": true, "asset_catalogue": {...}, "relation_catalogue": {...},
+                       "task_catalogue": {...}}
+        (registry vocabulary for :meth:`EnvironmentGenerationAgent.fetch_intent_from_prompt`)
+
+    {"cmd": "compile_intent", "intent_dict": {...}}
+      → {"ok": true, "spec_dict": {...}, "has_resolution_errors": bool,
+                       "trace": [{"stage": "...", "query": "...", ...}]}
+        (validates :class:`EnvironmentIntentSpec` and compiles to initial graph spec)
+
     {"cmd": "shutdown"}
       → {"ok": true}   # sidecar exits cleanly after replying
 
@@ -141,6 +151,14 @@ def _serve() -> int:
                 _send(_handle_render_spec(app, req, _render_thumbnails_with_app, ArenaEnvInitialGraphSpec))
                 continue
 
+            if cmd == "build_catalogues":
+                _send(_handle_build_catalogues())
+                continue
+
+            if cmd == "compile_intent":
+                _send(_handle_compile_intent(req))
+                continue
+
             _send({"ok": False, "error": f"unknown cmd: {cmd!r}"})
 
         return 0
@@ -173,6 +191,64 @@ def _handle_validate_spec(req: dict[str, Any], spec_cls) -> dict[str, Any]:
     return {"ok": True, "spec_dict": spec.to_dict()}
 
 
+def _handle_build_catalogues() -> dict[str, Any]:
+    """Return asset/relation/task catalogues for the env-generation agent."""
+    from dataclasses import asdict  # noqa: PLC0415
+
+    from isaaclab_arena.agentic_environment_generation.environment_generation_agent import (  # noqa: PLC0415
+        build_asset_catalogue,
+        build_relation_catalogue,
+        build_task_catalogue,
+    )
+
+    try:
+        asset_catalogue = build_asset_catalogue()
+        relation_catalogue = build_relation_catalogue()
+        task_catalogue = build_task_catalogue()
+    except Exception as exc:
+        return {"ok": False, "error": f"catalogue build failed: {exc}", "traceback": traceback.format_exc()}
+
+    return {
+        "ok": True,
+        "asset_catalogue": asdict(asset_catalogue),
+        "relation_catalogue": {
+            "relations": [asdict(entry) for entry in relation_catalogue.relations],
+        },
+        "task_catalogue": {
+            "tasks": [asdict(entry) for entry in task_catalogue.tasks],
+        },
+    }
+
+
+def _handle_compile_intent(req: dict[str, Any]) -> dict[str, Any]:
+    """Validate an EnvironmentIntentSpec and compile it to an initial graph spec."""
+    from dataclasses import asdict  # noqa: PLC0415
+
+    from isaaclab_arena.agentic_environment_generation.environment_intent_spec import (  # noqa: PLC0415
+        EnvironmentIntentSpec,
+    )
+    from isaaclab_arena.agentic_environment_generation.intent_compiler import IntentCompiler  # noqa: PLC0415
+
+    intent_dict = req.get("intent_dict")
+    if not isinstance(intent_dict, dict):
+        return {"ok": False, "error": "compile_intent requires mapping 'intent_dict'"}
+
+    try:
+        intent = EnvironmentIntentSpec.model_validate(intent_dict)
+        compiler = IntentCompiler()
+        spec = compiler.compile(intent)
+    except Exception as exc:
+        return {"ok": False, "error": f"intent compile failed: {exc}", "traceback": traceback.format_exc()}
+
+    return {
+        "ok": True,
+        "spec_dict": spec.to_dict(),
+        "has_resolution_errors": compiler.has_resolution_errors,
+        "trace": [asdict(event) for event in compiler.trace],
+        "reasoning": intent.reasoning,
+    }
+
+
 def _handle_render_spec(
     app,
     req: dict[str, Any],
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py
index 546921e3b..d54a01462 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py
@@ -106,6 +106,22 @@ def validate_yaml_text(self, yaml_text: str) -> dict[str, Any]:
         with self._lock:
             return self._request({"cmd": "validate_spec", "yaml_text": yaml_text})
 
+    def build_catalogues(self) -> dict[str, Any]:
+        """Build asset/relation/task catalogues from warm registries in the sidecar."""
+        if not self.is_alive():
+            raise SimAppSidecarError("SimApp sidecar is not running — start it first")
+
+        with self._lock:
+            return self._request({"cmd": "build_catalogues"})
+
+    def compile_intent(self, intent_dict: dict[str, Any]) -> dict[str, Any]:
+        """Validate and compile an EnvironmentIntentSpec in the sidecar."""
+        if not self.is_alive():
+            raise SimAppSidecarError("SimApp sidecar is not running — start it first")
+
+        with self._lock:
+            return self._request({"cmd": "compile_intent", "intent_dict": intent_dict})
+
     def render_spec(self, spec: ArenaEnvInitialGraphSpec) -> dict[str, bytes]:
         """Ask the sidecar to render thumbnails for ``spec``."""
         if not self.is_alive():
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
index 7d5b95f89..9eae8c3c1 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
@@ -10,9 +10,15 @@
     /isaac-sim/python.sh -m isaaclab_arena_examples.agentic_environment_generation.review_gui.server \\
         --yaml isaaclab_arena/tests/test_data/pick_and_place_maple_table_init_env_graph.yaml
 
+    # Prompt-only (empty editor until you generate or paste YAML):
+    /isaac-sim/python.sh -m isaaclab_arena_examples.agentic_environment_generation.review_gui.server
+
 Registry lookups (task kinds, relation kinds, asset USD paths) run in a
 persistent SimApp sidecar so YAML re-validation stays fast after the first
 ~30s sidecar boot. Thumbnails are rendered live by the same sidecar.
+
+Natural-language generation calls the LLM from Streamlit (``NV_API_KEY``) and
+compiles the returned intent in the sidecar where registries are warm.
 """
 
 from __future__ import annotations
@@ -27,6 +33,16 @@
 
 import streamlit as st
 
+from isaaclab_arena.agentic_environment_generation.asset_matcher import ASSET_ERROR_STAGES
+from isaaclab_arena.agentic_environment_generation.environment_generation_agent import (
+    AssetCatalogue,
+    EnvironmentGenerationAgent,
+    RelationCatalogue,
+    RelationCatalogueEntry,
+    TaskCatalogue,
+    TaskCatalogueEntry,
+)
+from isaaclab_arena.agentic_environment_generation.intent_compiler import IntentCompiler
 from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
 from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.dashboard import render_dashboard_html
 from isaaclab_arena_examples.agentic_environment_generation.review_gui.simapp_sidecar_client import (
@@ -38,12 +54,19 @@
 
 _SKIP_REGISTRY_CONTEXT: dict[str, Any] = {"skip_registry": True}
 
+_DEFAULT_GENERATION_PROMPT = (
+    "franka pick up avocado from the maple table and place it into a bowl on the table. "
+    "there are other veggies on the table as distractor"
+)
+
 _BROKEN_PLACEHOLDER_HTML = """<!DOCTYPE html><html><body style="
     font-family: ui-monospace, monospace;
     background:#15181d; color:#e4e6eb; padding:24px; margin:0;">
 <p>No visualization yet — fix the YAML errors to auto-render.</p>
 </body></html>"""
 
+_DEFAULT_SAVE_PATH = "isaaclab_arena_environments/llm_generated/generated_spec.yaml"
+
 
 @st.cache_resource(show_spinner="Booting Isaac Sim sidecar (≈30s first run, cached afterwards)…")
 def _get_simapp_sidecar() -> SimAppSidecar | None:
@@ -114,6 +137,9 @@ def is_valid(self) -> bool:
 
 def validate_yaml_text(text: str) -> ValidationResult:
     """Parse YAML and validate via the SimApp sidecar (registry lookups run there)."""
+    if not text.strip():
+        return ValidationResult(spec=None, error=None)
+
     try:
         raw = yaml.safe_load(text)
     except Exception:
@@ -154,25 +180,210 @@ def validate_yaml_text(text: str) -> ValidationResult:
     return ValidationResult(spec=spec, error=None)
 
 
+@dataclass
+class CatalogueBundle:
+    """Asset/relation/task vocabulary fetched from the SimApp sidecar."""
+
+    asset_catalogue: AssetCatalogue
+    relation_catalogue: RelationCatalogue
+    task_catalogue: TaskCatalogue
+
+
+def _catalogues_from_sidecar_response(response: dict[str, Any]) -> CatalogueBundle:
+    asset_raw = response["asset_catalogue"]
+    relation_raw = response["relation_catalogue"]
+    task_raw = response["task_catalogue"]
+    return CatalogueBundle(
+        asset_catalogue=AssetCatalogue(
+            embodiments=list(asset_raw["embodiments"]),
+            backgrounds=list(asset_raw["backgrounds"]),
+            objects=list(asset_raw["objects"]),
+        ),
+        relation_catalogue=RelationCatalogue(
+            relations=[RelationCatalogueEntry(**entry) for entry in relation_raw["relations"]],
+        ),
+        task_catalogue=TaskCatalogue(
+            tasks=[TaskCatalogueEntry(**entry) for entry in task_raw["tasks"]],
+        ),
+    )
+
+
+def _get_catalogue_bundle() -> CatalogueBundle | None:
+    """Return cached catalogues built in the sidecar (registry lookups run there)."""
+    cached = st.session_state.get("catalogue_bundle")
+    if cached is not None:
+        return cached
+
+    sidecar = _ensure_sidecar()
+    if sidecar is None:
+        return None
+
+    try:
+        response = sidecar.build_catalogues()
+    except SimAppSidecarError as exc:
+        st.session_state["catalogue_error"] = str(exc)
+        _get_simapp_sidecar.clear()
+        return None
+
+    if not response.get("ok"):
+        st.session_state["catalogue_error"] = response.get("error", "catalogue build failed")
+        return None
+
+    bundle = _catalogues_from_sidecar_response(response)
+    st.session_state["catalogue_bundle"] = bundle
+    st.session_state.pop("catalogue_error", None)
+    return bundle
+
+
+def _get_generation_agent() -> EnvironmentGenerationAgent | None:
+    """Lazy-init the LLM agent when ``NV_API_KEY`` is available."""
+    if st.session_state.get("generation_agent_error"):
+        return None
+    agent = st.session_state.get("generation_agent")
+    if agent is not None:
+        return agent
+    try:
+        agent = EnvironmentGenerationAgent()
+    except AssertionError as exc:
+        st.session_state["generation_agent_error"] = str(exc)
+        return None
+    except Exception as exc:
+        st.session_state["generation_agent_error"] = f"{type(exc).__name__}: {exc}"
+        return None
+    st.session_state["generation_agent"] = agent
+    st.session_state.pop("generation_agent_error", None)
+    return agent
+
+
+def _format_trace_lines(trace: list[dict[str, Any]], *, errors_only: bool = False) -> str:
+    error_stages = ASSET_ERROR_STAGES | IntentCompiler._ERROR_TRACE_STAGES
+    lines: list[str] = []
+    for event in trace:
+        stage = event.get("stage", "")
+        if errors_only and stage not in error_stages:
+            continue
+        chosen = event.get("chosen")
+        chosen_str = chosen if chosen is not None else "<none>"
+        note = event.get("note") or ""
+        note_str = f"  [{note}]" if note else ""
+        lines.append(f"{stage:34s} {event.get('query', ''):24s} -> {chosen_str}{note_str}")
+    return "\n".join(lines)
+
+
+def _apply_generated_yaml(yaml_text: str) -> None:
+    """Push compiled spec YAML into the editor and force a re-render on the next pass."""
+    st.session_state["edited_text"] = yaml_text
+    st.session_state["last_rendered_text"] = ""
+    st.session_state["editor_version"] = st.session_state.get("editor_version", 0) + 1
+
+
+def run_generation_pipeline(prompt: str) -> tuple[bool, str]:
+    """Call the LLM, compile intent in the sidecar, and load YAML into the editor."""
+    prompt = prompt.strip()
+    if not prompt:
+        return False, "Enter a prompt describing the environment."
+
+    agent = _get_generation_agent()
+    if agent is None:
+        err = st.session_state.get(
+            "generation_agent_error",
+            "Set NV_API_KEY in the environment before generating specs.",
+        )
+        return False, err
+
+    catalogues = _get_catalogue_bundle()
+    if catalogues is None:
+        err = st.session_state.get(
+            "catalogue_error",
+            "SimApp sidecar is unavailable — cannot build asset catalogues.",
+        )
+        return False, err
+
+    try:
+        intent_data, _raw = agent.fetch_intent_from_prompt(
+            prompt,
+            asset_catalog=catalogues.asset_catalogue,
+            relation_catalog=catalogues.relation_catalogue,
+            task_catalog=catalogues.task_catalogue,
+        )
+    except Exception:
+        return False, traceback.format_exc()
+
+    sidecar = _ensure_sidecar()
+    if sidecar is None:
+        return False, "SimApp sidecar is unavailable — cannot compile intent."
+
+    try:
+        response = sidecar.compile_intent(intent_data)
+    except SimAppSidecarError as exc:
+        _get_simapp_sidecar.clear()
+        return False, str(exc)
+
+    if not response.get("ok"):
+        err = response.get("error", "intent compile failed")
+        tb = response.get("traceback", "")
+        message = f"{err}\n\n{tb}" if tb else str(err)
+        return False, message
+
+    try:
+        yaml_text = yaml.safe_dump(response["spec_dict"], sort_keys=False)
+    except Exception:
+        return False, traceback.format_exc()
+
+    _apply_generated_yaml(yaml_text)
+
+    reasoning = response.get("reasoning", "")
+    if reasoning:
+        st.session_state["last_generation_reasoning"] = reasoning
+
+    trace = response.get("trace") or []
+    if trace:
+        st.session_state["last_generation_trace"] = trace
+
+    if response.get("has_resolution_errors"):
+        error_trace = _format_trace_lines(trace, errors_only=True)
+        return (
+            True,
+            (
+                "Spec generated with resolution warnings — review the trace below and edit the YAML as needed.\n\n"
+                f"{error_trace}"
+            ),
+        )
+
+    return True, "Spec generated and loaded into the YAML editor."
+
+
 def parse_args() -> argparse.Namespace:
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument(
         "--yaml",
         type=Path,
-        required=True,
-        help="Path to the ArenaEnvInitialGraphSpec YAML to open in the editor.",
+        default=None,
+        help="Optional path to an ArenaEnvInitialGraphSpec YAML to open in the editor.",
     )
     return parser.parse_args()
 
 
-def initialize_state(yaml_path: Path) -> None:
+def initialize_state(yaml_path: Path | None) -> None:
     """Seed ``st.session_state`` from disk exactly once per session."""
-    if st.session_state.get("_yaml_path") == str(yaml_path):
+    session_key = str(yaml_path.resolve()) if yaml_path is not None else ""
+    if st.session_state.get("_yaml_path") == session_key:
+        return
+
+    st.session_state["_yaml_path"] = session_key
+    st.session_state.setdefault("generation_prompt", _DEFAULT_GENERATION_PROMPT)
+    st.session_state.setdefault("editor_version", 0)
+
+    if yaml_path is None:
+        st.session_state["original_text"] = ""
+        st.session_state["edited_text"] = ""
+        st.session_state["last_rendered_text"] = ""
+        st.session_state["rendered_html"] = ""
+        st.session_state["save_path"] = _DEFAULT_SAVE_PATH
         return
 
     original_text = yaml_path.read_text(encoding="utf-8")
 
-    st.session_state["_yaml_path"] = str(yaml_path)
     st.session_state["original_text"] = original_text
     st.session_state["edited_text"] = original_text
     st.session_state["last_rendered_text"] = original_text
@@ -186,6 +397,8 @@ def initialize_state(yaml_path: Path) -> None:
 
 
 def render_validation_badge(validation: ValidationResult) -> None:
+    if validation.spec is None and validation.error is None:
+        return
     if validation.is_valid:
         spec = validation.spec
         st.success(
@@ -200,15 +413,18 @@ def render_validation_badge(validation: ValidationResult) -> None:
 def render_save_button(validation: ValidationResult) -> None:
     can_save = validation.is_valid
     save_path_str = st.session_state["save_path"]
+    save_label = f"Save to {Path(save_path_str).name}" if save_path_str else "Save YAML"
 
     if st.button(
-        f"Save to {Path(save_path_str).name}",
+        save_label,
         disabled=not can_save,
         use_container_width=True,
         help=f"Writes the editor contents to {save_path_str}. Disabled while YAML is invalid.",
     ):
         try:
-            Path(save_path_str).write_text(st.session_state["edited_text"], encoding="utf-8")
+            out_path = Path(save_path_str)
+            out_path.parent.mkdir(parents=True, exist_ok=True)
+            out_path.write_text(st.session_state["edited_text"], encoding="utf-8")
             st.session_state["original_text"] = st.session_state["edited_text"]
             st.toast(f"Saved → {save_path_str}", icon="💾")
         except OSError as exc:
@@ -219,13 +435,13 @@ def render_save_button(validation: ValidationResult) -> None:
             "Save path",
             value=save_path_str,
             key="save_path_input",
-            help="Defaults to the YAML file passed via --yaml.",
+            help="Defaults to the YAML file passed via --yaml, or a generated-spec path when none was given.",
         )
         if new_path and new_path != save_path_str:
             st.session_state["save_path"] = new_path
 
 
-def render_editor_panel(yaml_path: Path) -> ValidationResult:
+def render_editor_panel(yaml_path: Path | None) -> ValidationResult:
     try:
         from streamlit_ace import st_ace  # noqa: PLC0415
     except ImportError as exc:
@@ -238,8 +454,12 @@ def render_editor_panel(yaml_path: Path) -> ValidationResult:
         st.stop()
 
     st.subheader("YAML editor")
-    st.caption(f"Source: `{yaml_path}`")
+    if yaml_path is not None:
+        st.caption(f"Source: `{yaml_path}`")
+    else:
+        st.caption("No file loaded — generate a spec or paste YAML.")
 
+    editor_key = str(yaml_path) if yaml_path is not None else "new"
     new_text = st_ace(
         value=st.session_state["edited_text"],
         language="yaml",
@@ -252,7 +472,7 @@ def render_editor_panel(yaml_path: Path) -> ValidationResult:
         wrap=False,
         auto_update=False,
         min_lines=30,
-        key=f"ace_editor::{yaml_path}",
+        key=f"ace_editor::{editor_key}::{st.session_state.get('editor_version', 0)}",
     )
     if new_text is not None:
         st.session_state["edited_text"] = new_text
@@ -271,8 +491,52 @@ def render_editor_panel(yaml_path: Path) -> ValidationResult:
     return validation
 
 
+def render_generation_panel() -> None:
+    """Prompt input and generate-spec controls (top of the left column)."""
+    st.subheader("Generate from prompt")
+    st.caption("Calls the env-generation agent (LLM) then compiles intent in the SimApp sidecar.")
+
+    prompt = st.text_area(
+        "Prompt",
+        value=st.session_state.get("generation_prompt", _DEFAULT_GENERATION_PROMPT),
+        height=120,
+        placeholder="Describe the robot task, scene, objects, and distractors…",
+    )
+    st.session_state["generation_prompt"] = prompt
+
+    agent_error = st.session_state.get("generation_agent_error")
+    if agent_error:
+        st.info(f"LLM agent unavailable: {agent_error}", icon="ℹ️")
+
+    if st.button("Generate & compile", type="primary", use_container_width=True):
+        with st.spinner("Generating spec (LLM call + sidecar compile)…"):
+            ok, message = run_generation_pipeline(st.session_state["generation_prompt"])
+        if ok:
+            if "resolution warnings" in message:
+                st.warning(message, icon="⚠️")
+            else:
+                st.success(message, icon="✅")
+            st.rerun()
+        else:
+            st.error(f"Generation failed\n\n```\n{message}\n```", icon="🛑")
+
+    reasoning = st.session_state.get("last_generation_reasoning")
+    if reasoning:
+        with st.expander("Agent reasoning (last run)", expanded=False):
+            st.markdown(reasoning)
+
+    trace = st.session_state.get("last_generation_trace")
+    if trace:
+        with st.expander("Resolution trace (last run)", expanded=False):
+            st.code(_format_trace_lines(trace), language=None)
+
+
 def render_visualization_panel() -> None:
     st.subheader("Visualization")
+    if not st.session_state.get("last_rendered_text", "").strip():
+        st.caption("Generate or enter valid YAML to see the visualization.")
+        return
+
     st.caption("Updates automatically when the YAML is valid.")
 
     st.components.v1.html(
@@ -290,8 +554,8 @@ def main() -> None:
     )
 
     args = parse_args()
-    yaml_path = args.yaml.resolve()
-    if not yaml_path.exists():
+    yaml_path = args.yaml.resolve() if args.yaml is not None else None
+    if yaml_path is not None and not yaml_path.exists():
         st.error(f"YAML file not found: {yaml_path}", icon="🛑")
         st.stop()
 
@@ -300,6 +564,7 @@ def main() -> None:
     st.markdown("### ArenaEnvInitialGraphSpec live editor")
     left, right = st.columns([2, 3], gap="large")
     with left:
+        render_generation_panel()
         render_editor_panel(yaml_path)
     with right:
         render_visualization_panel()

From 8aee26c70800649904fb43a8629daea83a19d04e Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Mon, 15 Jun 2026 09:47:33 -0700
Subject: [PATCH 10/19] Reorder review GUI dashboard: nodes, graph with unary
 sidebar, tasks.

Stack visualizer sections vertically with three node thumbnails per row and unary
constraints beside the Mermaid spatial graph instead of below it.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../review_gui/render/dashboard.py            | 18 ++++++++++-----
 .../review_gui/render/mermaid_graph.py        |  2 +-
 .../review_gui/render/panels.py               |  8 +++----
 .../review_gui/render/styles.py               | 22 +++++++++----------
 4 files changed, 28 insertions(+), 22 deletions(-)

diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/dashboard.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/dashboard.py
index 731b3b781..ee08bd731 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/dashboard.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/dashboard.py
@@ -35,19 +35,25 @@ def render_dashboard_html(spec: ArenaEnvInitialGraphSpec, thumbnails: dict[str,
   <p class="sub">{len(spec.nodes)} nodes · {len(spec.tasks)} tasks · initial state: <code>{html_lib.escape(initial_state.id)}</code></p>
 </header>
 <main>
+  <section class="panel nodes-panel">
+    <h2>Nodes</h2>
+    <div class="node-grid">{render_node_cards(spec, thumbnails)}</div>
+  </section>
   <section class="panel graph-panel">
     <h2>Spatial graph <span class="muted">(initial state: <code>{html_lib.escape(initial_state.id)}</code>)</span></h2>
-    <pre class="mermaid">{render_mermaid_graph(spec, initial_state)}</pre>
-    {render_unary_constraints(initial_state)}
+    <div class="graph-row">
+      <div class="graph-mermaid">
+        <pre class="mermaid">{render_mermaid_graph(spec, initial_state)}</pre>
+      </div>
+      <aside class="graph-unary">
+        {render_unary_constraints(initial_state)}
+      </aside>
+    </div>
   </section>
   <section class="panel tasks-panel">
     <h2>Tasks</h2>
     {render_tasks_table(spec)}
   </section>
-  <section class="panel nodes-panel">
-    <h2>Nodes</h2>
-    <div class="node-grid">{render_node_cards(spec, thumbnails)}</div>
-  </section>
 </main>
 <script>mermaid.initialize({{ startOnLoad: true, theme: 'dark', themeVariables: {{ fontFamily: 'ui-monospace, monospace' }} }});</script>
 </body>
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/mermaid_graph.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/mermaid_graph.py
index 21b57ce48..7ec9c3fb0 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/mermaid_graph.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/mermaid_graph.py
@@ -20,7 +20,7 @@ def render_mermaid_graph(spec: ArenaEnvInitialGraphSpec, state: ArenaEnvGraphSta
         subject -->|kind| reference
 
     Unary spatial constraints (no reference) are omitted from the graph and
-    listed below it by :func:`render_unary_constraints` so their params are
+    listed to its right by :func:`render_unary_constraints` so their params are
     visible.
 
     Task constraints with a child are drawn as dashed edges:
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/panels.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/panels.py
index 1f3675b69..8eeeae19e 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/panels.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/panels.py
@@ -14,7 +14,7 @@
 
 
 def render_unary_constraints(state: ArenaEnvGraphStateSpec) -> str:
-    """List constraints without a reference below the graph (anchors, position_limits, ...)."""
+    """List constraints without a reference beside the spatial graph."""
     rows = []
     for constraint in state.spatial_constraints:
         if constraint.reference is not None:
@@ -30,10 +30,10 @@ def render_unary_constraints(state: ArenaEnvGraphStateSpec) -> str:
             f" on <code>{html_lib.escape(constraint.subject)}</code>{params}</li>"
         )
     if not rows:
-        return ""
+        return '<p class="muted unary-empty"><em>No unary constraints.</em></p>'
     return (
-        f'<details open class="unary"><summary>Unary constraints ({len(rows)})</summary>'
-        f'<ul>{"".join(rows)}</ul></details>'
+        f'<h3 class="unary-heading">Unary constraints <span class="muted">({len(rows)})</span></h3>'
+        f'<ul class="unary-list">{"".join(rows)}</ul>'
     )
 
 
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/styles.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/styles.py
index 279ad349d..b2638549c 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/styles.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/render/styles.py
@@ -19,14 +19,18 @@
 header { margin-bottom: 16px; }
 header h1 { margin: 0; font-size: 28px; font-weight: 700; }
 header .sub { margin: 4px 0 0; color: var(--fg-muted); font-size: 13px; }
-main { display: grid; grid-template-columns: 1fr 1fr; grid-template-rows: auto auto;
-       grid-template-areas: "graph nodes" "tasks nodes"; gap: 16px; }
-.graph-panel { grid-area: graph; }
-.tasks-panel { grid-area: tasks; }
-.nodes-panel { grid-area: nodes; }
+main { display: flex; flex-direction: column; gap: 16px; }
 .panel { background: var(--bg-elev); border: 1px solid var(--border); border-radius: 8px; padding: 16px; }
 .panel h2 { margin: 0 0 12px; font-size: 16px; font-weight: 600; letter-spacing: 0.02em; }
 .panel h2 .muted { color: var(--fg-muted); font-weight: 400; font-size: 13px; }
+.graph-row { display: grid; grid-template-columns: minmax(0, 1fr) minmax(220px, 300px); gap: 16px; align-items: start; }
+.graph-mermaid { min-width: 0; }
+.graph-unary { background: var(--bg-elev2); border: 1px solid var(--border); border-radius: 6px; padding: 12px; }
+.unary-heading { margin: 0 0 10px; font-size: 13px; font-weight: 600; letter-spacing: 0.02em; }
+.unary-heading .muted { font-weight: 400; }
+.unary-list { margin: 0; padding-left: 18px; list-style: disc; color: var(--fg); }
+.unary-list li { padding: 4px 0; font-size: 12px; }
+.unary-empty { margin: 0; font-size: 12px; }
 code { font-family: ui-monospace, 'SF Mono', Menlo, monospace; font-size: 12px;
        background: var(--bg-elev2); padding: 1px 6px; border-radius: 4px; }
 pre { font-family: ui-monospace, 'SF Mono', Menlo, monospace; font-size: 12px;
@@ -44,17 +48,13 @@
 .badge.type-position_limits, .badge.type-at_pose, .badge.type-at_position { background: #6b3a7a; }
 .badge.type-task { background: #2f343d; border: 1px solid #4a5; color: var(--accent); }
 .mermaid { background: var(--bg-elev2); padding: 8px; border-radius: 6px; min-height: 220px;
-           display: flex; align-items: center; justify-content: center; }
-.unary { margin-top: 12px; }
-.unary summary { cursor: pointer; color: var(--fg-muted); font-size: 13px; padding: 4px 0; }
-.unary ul { margin: 8px 0 0; padding-left: 20px; list-style: disc; color: var(--fg); }
-.unary li { padding: 3px 0; }
+           display: flex; align-items: center; justify-content: center; margin: 0; }
 table.tasks { width: 100%; border-collapse: collapse; }
 table.tasks th, table.tasks td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border);
                                   vertical-align: top; font-size: 12px; }
 table.tasks th { color: var(--fg-muted); font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em; }
 table.tasks pre { padding: 6px 8px; font-size: 11px; }
-.node-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 12px; }
+.node-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; }
 .node-card { background: var(--bg-elev2); border: 1px solid var(--border); border-radius: 8px;
              padding: 12px; display: flex; flex-direction: column; gap: 10px; }
 .node-card .thumb { aspect-ratio: 1 / 1; background: linear-gradient(135deg, #2a2f37, #1c2026);

From 8bd64e80c7115fec28f254f86c6e57804f433328 Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Mon, 15 Jun 2026 10:02:17 -0700
Subject: [PATCH 11/19] Add 16-env sim preview rollout to the review GUI
 sidecar.

Link YAML to arena env, solve relations, run 50 zero-action steps, and show
overview captures after reset and rollout in the visualization panel.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../review_gui/sim_preview.py                 | 148 ++++++++++++++++++
 .../review_gui/simapp_sidecar.py              |  25 +++
 .../review_gui/simapp_sidecar_client.py       |   8 +
 .../review_gui/streamlit_ui.py                |  99 ++++++++++--
 4 files changed, 270 insertions(+), 10 deletions(-)
 create mode 100644 isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py

diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
new file mode 100644
index 000000000..fa8e963fe
--- /dev/null
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
@@ -0,0 +1,148 @@
+# Copyright (c) 2026, The Isaac Lab Arena Project Developers (https://github.com/isaac-sim/IsaacLab-Arena/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""16-env relation-solver rollout preview for the review GUI SimApp sidecar."""
+
+from __future__ import annotations
+
+import argparse
+import contextlib
+import math
+import sys
+import time
+import uuid
+from pathlib import Path
+from typing import Any
+
+from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
+
+PREVIEW_CACHE_DIR = Path(__file__).resolve().parents[3] / ".cache" / "llm_env_gen_sim_preview"
+
+NUM_ENVS = 16
+ENV_SPACING_M = 1.5
+NUM_STEPS = 50
+
+
+def _preview_args() -> argparse.Namespace:
+    return argparse.Namespace(
+        num_envs=NUM_ENVS,
+        env_spacing=ENV_SPACING_M,
+        device="cuda:0",
+        disable_fabric=False,
+        solve_relations=True,
+        placement_seed=None,
+        resolve_on_reset=False,
+        random_yaw_init=False,
+        mimic=False,
+        distributed=False,
+        presets=None,
+    )
+
+
+def _overview_camera(
+    num_envs: int, env_spacing: float
+) -> tuple[tuple[float, float, float], tuple[float, float, float]]:
+    """Return (eye, target) for a diagonal overview of the env grid."""
+    cols = int(math.ceil(math.sqrt(num_envs)))
+    rows = int(math.ceil(num_envs / cols))
+    span_x = max((cols - 1) * env_spacing, env_spacing)
+    span_y = max((rows - 1) * env_spacing, env_spacing)
+    cx, cy = span_x * 0.5, span_y * 0.5
+    radius = max(span_x, span_y) + env_spacing
+    eye = (cx + radius * 0.2, cy - radius * 1.15, radius * 1.25)
+    target = (cx, cy, 0.35)
+    return eye, target
+
+
+def _capture_viewport(app, cache_path: Path) -> bytes | None:
+    from omni.kit.viewport.utility import capture_viewport_to_file, get_active_viewport  # noqa: PLC0415
+
+    from isaaclab_arena_examples.agentic_environment_generation.review_gui.thumbnail_render import (  # noqa: PLC0415
+        _wait_for_capture,
+    )
+
+    viewport = get_active_viewport()
+    cache_path.parent.mkdir(parents=True, exist_ok=True)
+    capture_obj = capture_viewport_to_file(viewport, str(cache_path))
+    for _ in range(10):
+        app.update()
+    _wait_for_capture(app, capture_obj, cache_path, max_updates=300)
+    if cache_path.exists() and cache_path.stat().st_size > 0:
+        return cache_path.read_bytes()
+    return None
+
+
+def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
+    """Link spec → arena env → relation solver → 50 zero-action steps; capture overview frames."""
+    import yaml
+
+    from isaaclab_arena.environments.arena_env_builder import ArenaEnvBuilder
+    from isaaclab_arena.policy.zero_action_policy import ZeroActionPolicy, ZeroActionPolicyArgs
+    from isaaclab_arena.utils.isaaclab_utils.simulation_app import reapply_viewer_cfg, teardown_simulation_app
+
+    raw = yaml.safe_load(yaml_text)
+    if not isinstance(raw, dict):
+        raise ValueError(f"expected mapping, got {type(raw).__name__}")
+
+    initial_spec = ArenaEnvInitialGraphSpec.model_validate(raw)
+    graph_spec = initial_spec.link()
+    arena_env = graph_spec.to_arena_env()
+    preview_name = f"{arena_env.name}_preview_{uuid.uuid4().hex[:8]}"
+    arena_env.name = preview_name
+
+    args = _preview_args()
+    builder = ArenaEnvBuilder(arena_env, args)
+    policy = ZeroActionPolicy(ZeroActionPolicyArgs())
+
+    PREVIEW_CACHE_DIR.mkdir(parents=True, exist_ok=True)
+    stamp = int(time.time() * 1000)
+    first_path = PREVIEW_CACHE_DIR / f"{preview_name}_{stamp}_first.png"
+    last_path = PREVIEW_CACHE_DIR / f"{preview_name}_{stamp}_last.png"
+
+    env = None
+    try:
+        env = builder.make_registered()
+        reapply_viewer_cfg(env)
+
+        eye, target = _overview_camera(args.num_envs, args.env_spacing)
+        env.unwrapped.sim.set_camera_view(eye, target)
+        for _ in range(15):
+            app.update()
+
+        obs, _ = env.reset()
+        for _ in range(10):
+            app.update()
+
+        if _capture_viewport(app, first_path) is None:
+            raise RuntimeError("failed to capture first-frame overview screenshot")
+
+        for _ in range(NUM_STEPS):
+            action = policy.get_action(env, obs)
+            obs, _, _, _, _ = env.step(action)
+
+        for _ in range(10):
+            app.update()
+
+        if _capture_viewport(app, last_path) is None:
+            raise RuntimeError("failed to capture last-frame overview screenshot")
+
+        print(
+            f"[sim_preview] captured {NUM_ENVS} envs @ {ENV_SPACING_M}m spacing, {NUM_STEPS} zero-action steps",
+            file=sys.stderr,
+        )
+        return {
+            "ok": True,
+            "first_frame": str(first_path),
+            "last_frame": str(last_path),
+            "env_name": preview_name,
+            "num_envs": args.num_envs,
+            "env_spacing": args.env_spacing,
+            "num_steps": NUM_STEPS,
+        }
+    finally:
+        if env is not None:
+            with contextlib.suppress(Exception):
+                env.close()
+        teardown_simulation_app(suppress_exceptions=True)
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
index 5d40a8f05..fa2179e65 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
@@ -53,6 +53,11 @@
                        "trace": [{"stage": "...", "query": "...", ...}]}
         (validates :class:`EnvironmentIntentSpec` and compiles to initial graph spec)
 
+    {"cmd": "run_sim_preview", "yaml_text": "..."}
+      → {"ok": true, "first_frame": "/abs/first.png", "last_frame": "/abs/last.png",
+                       "num_envs": 16, "env_spacing": 1.5, "num_steps": 50}
+        (link → to_arena_env → relation solver → 50 zero-action steps; overview captures)
+
     {"cmd": "shutdown"}
       → {"ok": true}   # sidecar exits cleanly after replying
 
@@ -159,6 +164,10 @@ def _serve() -> int:
                 _send(_handle_compile_intent(req))
                 continue
 
+            if cmd == "run_sim_preview":
+                _send(_handle_run_sim_preview(app, req))
+                continue
+
             _send({"ok": False, "error": f"unknown cmd: {cmd!r}"})
 
         return 0
@@ -249,6 +258,22 @@ def _handle_compile_intent(req: dict[str, Any]) -> dict[str, Any]:
     }
 
 
+def _handle_run_sim_preview(app, req: dict[str, Any]) -> dict[str, Any]:
+    """Build linked env, solve relations, roll out zero actions, capture overview frames."""
+    from isaaclab_arena_examples.agentic_environment_generation.review_gui.sim_preview import (  # noqa: PLC0415
+        run_sim_preview,
+    )
+
+    yaml_text = req.get("yaml_text")
+    if not isinstance(yaml_text, str):
+        return {"ok": False, "error": "run_sim_preview requires string 'yaml_text'"}
+
+    try:
+        return run_sim_preview(app, yaml_text)
+    except Exception as exc:
+        return {"ok": False, "error": f"sim preview failed: {exc}", "traceback": traceback.format_exc()}
+
+
 def _handle_render_spec(
     app,
     req: dict[str, Any],
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py
index d54a01462..b7758ed33 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar_client.py
@@ -122,6 +122,14 @@ def compile_intent(self, intent_dict: dict[str, Any]) -> dict[str, Any]:
         with self._lock:
             return self._request({"cmd": "compile_intent", "intent_dict": intent_dict})
 
+    def run_sim_preview(self, yaml_text: str) -> dict[str, Any]:
+        """Link, build env, solve relations, and capture overview rollout frames."""
+        if not self.is_alive():
+            raise SimAppSidecarError("SimApp sidecar is not running — start it first")
+
+        with self._lock:
+            return self._request({"cmd": "run_sim_preview", "yaml_text": yaml_text})
+
     def render_spec(self, spec: ArenaEnvInitialGraphSpec) -> dict[str, bytes]:
         """Ask the sidecar to render thumbnails for ``spec``."""
         if not self.is_alive():
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
index 9eae8c3c1..4e3f04b56 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
@@ -45,6 +45,11 @@
 from isaaclab_arena.agentic_environment_generation.intent_compiler import IntentCompiler
 from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
 from isaaclab_arena_examples.agentic_environment_generation.review_gui.render.dashboard import render_dashboard_html
+from isaaclab_arena_examples.agentic_environment_generation.review_gui.sim_preview import (
+    ENV_SPACING_M,
+    NUM_ENVS,
+    NUM_STEPS,
+)
 from isaaclab_arena_examples.agentic_environment_generation.review_gui.simapp_sidecar_client import (
     SimAppSidecar,
     SimAppSidecarError,
@@ -353,6 +358,46 @@ def run_generation_pipeline(prompt: str) -> tuple[bool, str]:
     return True, "Spec generated and loaded into the YAML editor."
 
 
+def run_sim_preview_pipeline(yaml_text: str) -> tuple[bool, str]:
+    """Link, build, solve relations, and capture overview frames in the sidecar."""
+    validation = validate_yaml_text(yaml_text)
+    if not validation.is_valid:
+        return False, validation.error or "YAML must be valid before running sim preview."
+
+    sidecar = _ensure_sidecar()
+    if sidecar is None:
+        return False, "SimApp sidecar is unavailable — cannot run sim preview."
+
+    try:
+        response = sidecar.run_sim_preview(yaml_text)
+    except SimAppSidecarError as exc:
+        _get_simapp_sidecar.clear()
+        return False, str(exc)
+
+    if not response.get("ok"):
+        err = response.get("error", "sim preview failed")
+        tb = response.get("traceback", "")
+        message = f"{err}\n\n{tb}" if tb else str(err)
+        return False, message
+
+    try:
+        first_path = Path(response["first_frame"])
+        last_path = Path(response["last_frame"])
+        st.session_state["sim_preview_first"] = first_path.read_bytes()
+        st.session_state["sim_preview_last"] = last_path.read_bytes()
+    except OSError as exc:
+        return False, f"Failed to read preview frames: {exc}"
+
+    return (
+        True,
+        (
+            f"Sim preview complete — {response.get('num_envs', NUM_ENVS)} envs, "
+            f"{response.get('env_spacing', ENV_SPACING_M)} m spacing, "
+            f"{response.get('num_steps', NUM_STEPS)} steps."
+        ),
+    )
+
+
 def parse_args() -> argparse.Namespace:
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument(
@@ -531,20 +576,54 @@ def render_generation_panel() -> None:
             st.code(_format_trace_lines(trace), language=None)
 
 
-def render_visualization_panel() -> None:
+def render_visualization_panel(validation: ValidationResult) -> None:
     st.subheader("Visualization")
     if not st.session_state.get("last_rendered_text", "").strip():
         st.caption("Generate or enter valid YAML to see the visualization.")
-        return
-
-    st.caption("Updates automatically when the YAML is valid.")
+    else:
+        st.caption("Updates automatically when the YAML is valid.")
+        st.components.v1.html(
+            st.session_state["rendered_html"],
+            height=_IFRAME_HEIGHT_PX,
+            scrolling=True,
+        )
 
-    st.components.v1.html(
-        st.session_state["rendered_html"],
-        height=_IFRAME_HEIGHT_PX,
-        scrolling=True,
+    st.divider()
+    st.subheader("Sim preview")
+    st.caption(
+        f"Runs link → to_arena_env → relation solver, then {NUM_STEPS} zero-action steps "
+        f"with {NUM_ENVS} parallel envs at {ENV_SPACING_M} m spacing. "
+        "Overview captures are taken after reset and after the rollout."
     )
 
+    if st.button(
+        "Run link + relation solver preview",
+        type="secondary",
+        use_container_width=True,
+        disabled=not validation.is_valid,
+        help="Requires valid YAML and a healthy SimApp sidecar. This may take several minutes.",
+    ):
+        with st.spinner(
+            f"Building env, solving relations, and rolling out {NUM_STEPS} steps ({NUM_ENVS} envs @ {ENV_SPACING_M} m)…"
+        ):
+            ok, message = run_sim_preview_pipeline(st.session_state["edited_text"])
+        if ok:
+            st.success(message, icon="✅")
+            st.rerun()
+        else:
+            st.error(f"Sim preview failed\n\n```\n{message}\n```", icon="🛑")
+
+    first_frame = st.session_state.get("sim_preview_first")
+    last_frame = st.session_state.get("sim_preview_last")
+    if first_frame and last_frame:
+        frame_cols = st.columns(2)
+        with frame_cols[0]:
+            st.caption("Overview — frame 1 (after reset)")
+            st.image(first_frame, use_container_width=True)
+        with frame_cols[1]:
+            st.caption(f"Overview — frame 2 (after {NUM_STEPS} zero-action steps)")
+            st.image(last_frame, use_container_width=True)
+
 
 def main() -> None:
     st.set_page_config(
@@ -565,9 +644,9 @@ def main() -> None:
     left, right = st.columns([2, 3], gap="large")
     with left:
         render_generation_panel()
-        render_editor_panel(yaml_path)
+        validation = render_editor_panel(yaml_path)
     with right:
-        render_visualization_panel()
+        render_visualization_panel(validation)
 
 
 main()

From ab6f54a84a1d6c16d871ad06bd5619ed6779841e Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Mon, 15 Jun 2026 10:09:23 -0700
Subject: [PATCH 12/19] Fix viewer look-at when relation solver sets PosePerEnv
 poses.

Multi-env sim preview failed because get_viewer_cfg_look_at_object only
handled Pose and PoseRange; add as_single_pose and use it at call sites.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 isaaclab_arena/tasks/lift_object_task.py | 10 +++-------
 isaaclab_arena/tests/test_pose.py        | 21 ++++++++++++++++++++-
 isaaclab_arena/utils/cameras.py          |  5 ++---
 isaaclab_arena/utils/pose.py             | 12 ++++++++++++
 4 files changed, 37 insertions(+), 11 deletions(-)

diff --git a/isaaclab_arena/tasks/lift_object_task.py b/isaaclab_arena/tasks/lift_object_task.py
index 4c4461fd7..100c6f734 100644
--- a/isaaclab_arena/tasks/lift_object_task.py
+++ b/isaaclab_arena/tasks/lift_object_task.py
@@ -26,7 +26,7 @@
 from isaaclab_arena.tasks.task_base import TaskBase
 from isaaclab_arena.tasks.terminations import lift_object_il_success, lift_object_rl_success
 from isaaclab_arena.utils.cameras import get_viewer_cfg_look_at_object
-from isaaclab_arena.utils.pose import PoseRange
+from isaaclab_arena.utils.pose import as_single_pose
 
 
 @register_task
@@ -54,9 +54,7 @@ def __init__(
         self.background_scene = background_scene
 
         # Compute goal position from object's initial pose + delta
-        initial_pose = lift_object.get_initial_pose()
-        if isinstance(initial_pose, PoseRange):
-            initial_pose = initial_pose.get_midpoint()
+        initial_pose = as_single_pose(lift_object.get_initial_pose())
 
         # Store goal pose for success termination (IL/teleoperation uses fixed goal)
         self.goal_position_xyz = (
@@ -163,9 +161,7 @@ def __init__(
 
         self.minimum_height_to_lift = minimum_height_to_lift
         # Get object's initial pose to compute absolute target ranges
-        initial_pose = lift_object.get_initial_pose()
-        if isinstance(initial_pose, PoseRange):
-            initial_pose = initial_pose.get_midpoint()
+        initial_pose = as_single_pose(lift_object.get_initial_pose())
 
         # Compute absolute target ranges from deltas
         self.target_x_range = (
diff --git a/isaaclab_arena/tests/test_pose.py b/isaaclab_arena/tests/test_pose.py
index bba6405b1..e5b0cbe41 100644
--- a/isaaclab_arena/tests/test_pose.py
+++ b/isaaclab_arena/tests/test_pose.py
@@ -5,7 +5,7 @@
 
 import math
 
-from isaaclab_arena.utils.pose import Pose, PosePerEnv, rotate_quat_by_yaw, wrap_angle_to_pi
+from isaaclab_arena.utils.pose import Pose, PosePerEnv, PoseRange, as_single_pose, rotate_quat_by_yaw, wrap_angle_to_pi
 
 
 def _yaw_of(quat_xyzw: tuple[float, float, float, float]) -> float:
@@ -40,6 +40,25 @@ def test_pose_composition():
     assert T_C_A.rotation_xyzw == (0.0, 0.0, 0.0, 1.0)
 
 
+def test_as_single_pose():
+    pose = Pose(position_xyz=(1.0, 2.0, 3.0))
+    assert as_single_pose(pose) is pose
+
+    pose_range = PoseRange(
+        position_xyz_min=(0.0, 0.0, 0.0),
+        position_xyz_max=(2.0, 4.0, 6.0),
+    )
+    assert as_single_pose(pose_range).position_xyz == (1.0, 2.0, 3.0)
+
+    pose_per_env = PosePerEnv(
+        poses=[
+            Pose(position_xyz=(1.0, 2.0, 3.0)),
+            Pose(position_xyz=(4.0, 5.0, 6.0)),
+        ]
+    )
+    assert as_single_pose(pose_per_env).position_xyz == (1.0, 2.0, 3.0)
+
+
 def test_pose_per_env_stores_poses():
     """Test that PosePerEnv stores the list of Pose objects correctly."""
     poses = [
diff --git a/isaaclab_arena/utils/cameras.py b/isaaclab_arena/utils/cameras.py
index 4567bb7e0..ddbb4c9e9 100644
--- a/isaaclab_arena/utils/cameras.py
+++ b/isaaclab_arena/utils/cameras.py
@@ -18,7 +18,7 @@
 
 from isaaclab_arena.assets.asset import Asset
 from isaaclab_arena.utils.configclass import make_configclass
-from isaaclab_arena.utils.pose import PoseRange
+from isaaclab_arena.utils.pose import as_single_pose
 
 
 def make_camera_observation_cfg(
@@ -114,8 +114,7 @@ def get_viewer_cfg_look_at_object(lookat_object: Asset, offset: np.ndarray) -> V
         print(f"{lookat_object.name} has no initial pose set. Using default ViewerCfg.")
         return ViewerCfg()
 
-    if isinstance(initial_pose, PoseRange):
-        initial_pose = initial_pose.get_midpoint()
+    initial_pose = as_single_pose(initial_pose)
 
     # TODO(cvolk): Add float coercion to Pose.__post_init__ so this conversion is unnecessary.
     # Ensure we only pass primitive Python floats (not NumPy scalars) into ViewerCfg,
diff --git a/isaaclab_arena/utils/pose.py b/isaaclab_arena/utils/pose.py
index ecc9289d6..3eb869df4 100644
--- a/isaaclab_arena/utils/pose.py
+++ b/isaaclab_arena/utils/pose.py
@@ -144,3 +144,15 @@ def get_midpoint(self) -> Pose:
             position_xyz=tuple(position_xyz.tolist()),
             rotation_xyzw=tuple(quat.tolist()),
         )
+
+
+def as_single_pose(pose: Pose | PoseRange | PosePerEnv) -> Pose:
+    """Return one representative ``Pose`` for viewer and bbox code that needs a single point.
+
+    ``PosePerEnv`` uses env 0; ``PoseRange`` uses its midpoint.
+    """
+    if isinstance(pose, PosePerEnv):
+        return pose.poses[0]
+    if isinstance(pose, PoseRange):
+        return pose.get_midpoint()
+    return pose

From adab971aa3cfe8ee89db2d34a8acc4e3ae15cb9d Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Mon, 15 Jun 2026 10:17:02 -0700
Subject: [PATCH 13/19] Tune sim preview: 10 steps and default scene viewport
 camera.

Drop the custom grid overview camera and task look-at-object offsets;
use Isaac Lab ViewerCfg like policy_runner and shorten the rollout.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../review_gui/sim_preview.py                 | 39 ++++++-------------
 .../review_gui/simapp_sidecar.py              |  4 +-
 .../review_gui/streamlit_ui.py                |  6 +--
 3 files changed, 16 insertions(+), 33 deletions(-)

diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
index fa8e963fe..a2b73b2d3 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
@@ -9,20 +9,21 @@
 
 import argparse
 import contextlib
-import math
 import sys
 import time
 import uuid
 from pathlib import Path
 from typing import Any
 
+from isaaclab.envs.common import ViewerCfg
+
 from isaaclab_arena.environments.arena_env_graph_spec import ArenaEnvInitialGraphSpec
 
 PREVIEW_CACHE_DIR = Path(__file__).resolve().parents[3] / ".cache" / "llm_env_gen_sim_preview"
 
 NUM_ENVS = 16
 ENV_SPACING_M = 1.5
-NUM_STEPS = 50
+NUM_STEPS = 10
 
 
 def _preview_args() -> argparse.Namespace:
@@ -41,21 +42,6 @@ def _preview_args() -> argparse.Namespace:
     )
 
 
-def _overview_camera(
-    num_envs: int, env_spacing: float
-) -> tuple[tuple[float, float, float], tuple[float, float, float]]:
-    """Return (eye, target) for a diagonal overview of the env grid."""
-    cols = int(math.ceil(math.sqrt(num_envs)))
-    rows = int(math.ceil(num_envs / cols))
-    span_x = max((cols - 1) * env_spacing, env_spacing)
-    span_y = max((rows - 1) * env_spacing, env_spacing)
-    cx, cy = span_x * 0.5, span_y * 0.5
-    radius = max(span_x, span_y) + env_spacing
-    eye = (cx + radius * 0.2, cy - radius * 1.15, radius * 1.25)
-    target = (cx, cy, 0.35)
-    return eye, target
-
-
 def _capture_viewport(app, cache_path: Path) -> bytes | None:
     from omni.kit.viewport.utility import capture_viewport_to_file, get_active_viewport  # noqa: PLC0415
 
@@ -75,12 +61,12 @@ def _capture_viewport(app, cache_path: Path) -> bytes | None:
 
 
 def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
-    """Link spec → arena env → relation solver → 50 zero-action steps; capture overview frames."""
+    """Link spec → arena env → relation solver → zero-action steps; capture viewport frames."""
     import yaml
 
     from isaaclab_arena.environments.arena_env_builder import ArenaEnvBuilder
     from isaaclab_arena.policy.zero_action_policy import ZeroActionPolicy, ZeroActionPolicyArgs
-    from isaaclab_arena.utils.isaaclab_utils.simulation_app import reapply_viewer_cfg, teardown_simulation_app
+    from isaaclab_arena.utils.isaaclab_utils.simulation_app import teardown_simulation_app
 
     raw = yaml.safe_load(yaml_text)
     if not isinstance(raw, dict):
@@ -103,20 +89,17 @@ def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
 
     env = None
     try:
-        env = builder.make_registered()
-        reapply_viewer_cfg(env)
-
-        eye, target = _overview_camera(args.num_envs, args.env_spacing)
-        env.unwrapped.sim.set_camera_view(eye, target)
-        for _ in range(15):
-            app.update()
+        # Match policy_runner: default Isaac Lab ViewerCfg (not task look-at-object offsets).
+        env_cfg = builder.compose_manager_cfg()
+        env_cfg.viewer = ViewerCfg()
+        env = builder.make_registered(env_cfg)
 
         obs, _ = env.reset()
         for _ in range(10):
             app.update()
 
         if _capture_viewport(app, first_path) is None:
-            raise RuntimeError("failed to capture first-frame overview screenshot")
+            raise RuntimeError("failed to capture first-frame viewport screenshot")
 
         for _ in range(NUM_STEPS):
             action = policy.get_action(env, obs)
@@ -126,7 +109,7 @@ def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
             app.update()
 
         if _capture_viewport(app, last_path) is None:
-            raise RuntimeError("failed to capture last-frame overview screenshot")
+            raise RuntimeError("failed to capture last-frame viewport screenshot")
 
         print(
             f"[sim_preview] captured {NUM_ENVS} envs @ {ENV_SPACING_M}m spacing, {NUM_STEPS} zero-action steps",
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
index fa2179e65..81d874d04 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
@@ -55,8 +55,8 @@
 
     {"cmd": "run_sim_preview", "yaml_text": "..."}
       → {"ok": true, "first_frame": "/abs/first.png", "last_frame": "/abs/last.png",
-                       "num_envs": 16, "env_spacing": 1.5, "num_steps": 50}
-        (link → to_arena_env → relation solver → 50 zero-action steps; overview captures)
+                       "num_envs": 16, "env_spacing": 1.5, "num_steps": 10}
+        (link → to_arena_env → relation solver → 10 zero-action steps; viewport captures)
 
     {"cmd": "shutdown"}
       → {"ok": true}   # sidecar exits cleanly after replying
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
index 4e3f04b56..4d669d81f 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
@@ -593,7 +593,7 @@ def render_visualization_panel(validation: ValidationResult) -> None:
     st.caption(
         f"Runs link → to_arena_env → relation solver, then {NUM_STEPS} zero-action steps "
         f"with {NUM_ENVS} parallel envs at {ENV_SPACING_M} m spacing. "
-        "Overview captures are taken after reset and after the rollout."
+        "Viewport captures use the default scene camera (same as policy_runner)."
     )
 
     if st.button(
@@ -618,10 +618,10 @@ def render_visualization_panel(validation: ValidationResult) -> None:
     if first_frame and last_frame:
         frame_cols = st.columns(2)
         with frame_cols[0]:
-            st.caption("Overview — frame 1 (after reset)")
+            st.caption("Viewport — frame 1 (after reset)")
             st.image(first_frame, use_container_width=True)
         with frame_cols[1]:
-            st.caption(f"Overview — frame 2 (after {NUM_STEPS} zero-action steps)")
+            st.caption(f"Viewport — frame 2 (after {NUM_STEPS} zero-action steps)")
             st.image(last_frame, use_container_width=True)
 
 

From 91ab7d182392642db70303784f11dd01d88a464b Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Tue, 16 Jun 2026 01:21:23 -0700
Subject: [PATCH 14/19] Fix repeat sim preview by sharing eval-runner env
 teardown.

Extract close_env_and_reset_sim so the sidecar resets SimulationContext,
closes the gym env, and clears CUDA cache between preview runs instead of
swallowing partial cleanup errors.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 isaaclab_arena/evaluation/eval_runner.py      | 27 +++++----------
 .../utils/isaaclab_utils/simulation_app.py    | 34 +++++++++++++++++++
 .../review_gui/sim_preview.py                 |  8 ++---
 3 files changed, 44 insertions(+), 25 deletions(-)

diff --git a/isaaclab_arena/evaluation/eval_runner.py b/isaaclab_arena/evaluation/eval_runner.py
index c1512700d..42a82169f 100644
--- a/isaaclab_arena/evaluation/eval_runner.py
+++ b/isaaclab_arena/evaluation/eval_runner.py
@@ -5,14 +5,12 @@
 
 import argparse
 import dataclasses
-import gc
 import json
 import math
 import os
 import subprocess
 import sys
 import tempfile
-import torch
 import traceback
 from gymnasium.wrappers import RecordVideo
 from pathlib import Path
@@ -24,7 +22,11 @@
 from isaaclab_arena.evaluation.policy_runner import get_policy_cls, rollout_policy
 from isaaclab_arena.metrics.aggregate_metrics import aggregate_metrics
 from isaaclab_arena.metrics.metrics_logger import MetricsLogger
-from isaaclab_arena.utils.isaaclab_utils.simulation_app import SimulationAppContext, teardown_simulation_app
+from isaaclab_arena.utils.isaaclab_utils.simulation_app import (
+    SimulationAppContext,
+    close_env_and_reset_sim,
+    collect_garbage_and_clear_cuda_cache,
+)
 from isaaclab_arena_environments.cli import get_arena_builder_from_cli, get_isaaclab_arena_environments_cli_parser
 
 if TYPE_CHECKING:
@@ -111,31 +113,18 @@ def get_policy_from_job(job: Job) -> "PolicyBase":
     return policy
 
 
-def _collect_garbage_and_clear_cuda_cache() -> None:
-    gc.collect()
-    if torch.cuda.is_available():
-        torch.cuda.empty_cache()
-
-
 def _close_policy(policy: "PolicyBase | None") -> None:
     try:
         if policy is not None:
             policy.close()
     finally:
-        _collect_garbage_and_clear_cuda_cache()
+        collect_garbage_and_clear_cuda_cache()
 
 
 def _close_env(env) -> None:
     if env is None:
         return
-    try:
-        teardown_simulation_app(suppress_exceptions=False, make_new_stage=True)
-    finally:
-        try:
-            # cleanup managers, including recorder manager closing hdf5 file
-            env.close()
-        finally:
-            _collect_garbage_and_clear_cuda_cache()
+    close_env_and_reset_sim(env)
 
 
 def _close_job_resources(policy: "PolicyBase | None", env) -> None:
@@ -326,7 +315,7 @@ def main():
                     finally:
                         policy = None
                         env = None
-                        _collect_garbage_and_clear_cuda_cache()
+                        collect_garbage_and_clear_cuda_cache()
 
             # Aggregate the metrics from the different experiments into a single view.
             if metrics_per_run:
diff --git a/isaaclab_arena/utils/isaaclab_utils/simulation_app.py b/isaaclab_arena/utils/isaaclab_utils/simulation_app.py
index 02db2a0f3..4593986e5 100644
--- a/isaaclab_arena/utils/isaaclab_utils/simulation_app.py
+++ b/isaaclab_arena/utils/isaaclab_utils/simulation_app.py
@@ -82,6 +82,40 @@ def teardown_simulation_app(suppress_exceptions: bool = False, make_new_stage: b
             omni.usd.get_context().new_stage()
 
 
+def collect_garbage_and_clear_cuda_cache() -> None:
+    """Run GC and release cached CUDA allocations after a sim env is torn down."""
+    import gc
+    import torch
+
+    gc.collect()
+    if torch.cuda.is_available():
+        torch.cuda.empty_cache()
+
+
+def close_env_and_reset_sim(
+    env=None,
+    *,
+    suppress_exceptions: bool = False,
+    make_new_stage: bool = True,
+) -> None:
+    """Tear down sim state and close a gym env so another can be built in the same SimApp.
+
+    Order matches :func:`isaaclab_arena.evaluation.eval_runner._close_env`: stop
+    :class:`~isaaclab.sim.SimulationContext`, open a fresh USD stage, then close
+    env managers and collect GPU garbage.
+    """
+    try:
+        teardown_simulation_app(suppress_exceptions=suppress_exceptions, make_new_stage=make_new_stage)
+    finally:
+        if env is not None:
+            if suppress_exceptions:
+                with suppress(Exception):
+                    env.close()
+            else:
+                env.close()
+        collect_garbage_and_clear_cuda_cache()
+
+
 def reapply_viewer_cfg(env) -> None:
     """Re-apply ViewerCfg camera position after visualizers are initialized.
 
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
index a2b73b2d3..36cebe0cc 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
@@ -8,7 +8,6 @@
 from __future__ import annotations
 
 import argparse
-import contextlib
 import sys
 import time
 import uuid
@@ -66,7 +65,7 @@ def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
 
     from isaaclab_arena.environments.arena_env_builder import ArenaEnvBuilder
     from isaaclab_arena.policy.zero_action_policy import ZeroActionPolicy, ZeroActionPolicyArgs
-    from isaaclab_arena.utils.isaaclab_utils.simulation_app import teardown_simulation_app
+    from isaaclab_arena.utils.isaaclab_utils.simulation_app import close_env_and_reset_sim
 
     raw = yaml.safe_load(yaml_text)
     if not isinstance(raw, dict):
@@ -125,7 +124,4 @@ def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
             "num_steps": NUM_STEPS,
         }
     finally:
-        if env is not None:
-            with contextlib.suppress(Exception):
-                env.close()
-        teardown_simulation_app(suppress_exceptions=True)
+        close_env_and_reset_sim(env)

From 8d4601d68ab4cc2d07ef5cfa0cc4a0eec22370f0 Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Tue, 16 Jun 2026 02:58:21 -0700
Subject: [PATCH 15/19] Run review GUI SimApp sidecar with Kit visualizer
 enabled.

Boot the persistent sidecar with --viz kit so thumbnails and sim preview
render in an interactive Kit viewport instead of headless mode.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../review_gui/simapp_sidecar.py                       |  2 +-
 .../review_gui/thumbnail_render.py                     | 10 +++++++---
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
index 81d874d04..17b1f727a 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/simapp_sidecar.py
@@ -5,7 +5,7 @@
 
 """Long-lived ``SimulationApp`` host process for the live review editor.
 
-Boots Kit's ``SimulationApp`` once on *its own* main thread and serves
+Boots Kit's ``SimulationApp`` once (with ``--viz kit``) on *its own* main thread and serves
 validation and thumbnail-render requests over a newline-delimited JSON-RPC
 pipe on stdin/stdout. The parent (``streamlit_ui.py`` running inside
 Streamlit) spawns exactly one of these and reuses it for the entire server
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/thumbnail_render.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/thumbnail_render.py
index d4ea06a9b..f63f17d4e 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/thumbnail_render.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/thumbnail_render.py
@@ -80,8 +80,13 @@ def _render_thumbnails_with_app(app, spec: ArenaEnvInitialGraphSpec) -> dict[str
     return resolved
 
 
+def _sidecar_launch_args() -> argparse.Namespace:
+    """AppLauncher args for the review GUI sidecar (Kit UI + viewport capture)."""
+    return argparse.Namespace(visualizer=["kit"], enable_cameras=True, livestream=-1)
+
+
 def _launch_simulation_app():
-    """Boot Isaac Sim's ``SimulationApp`` for headless viewport capture, or ``None`` on failure.
+    """Boot Isaac Sim's ``SimulationApp`` with the Kit visualizer, or ``None`` on failure.
 
     Kept as a tiny helper so the call site can lazy-import inside this
     function — module-level import of ``simulation_app`` would drag Kit
@@ -91,8 +96,7 @@ def _launch_simulation_app():
         # Lazy-import: keeps the default ``review_graph`` invocation Kit-free.
         from isaaclab_arena.utils.isaaclab_utils.simulation_app import get_app_launcher  # noqa: PLC0415
 
-        sim_args = argparse.Namespace(headless=True, enable_cameras=True, hide_ui=True, livestream=-1)
-        return get_app_launcher(sim_args).app
+        return get_app_launcher(_sidecar_launch_args()).app
     except Exception as exc:
         print(f"[thumbnail_render] SimulationApp launch failed: {exc}", file=sys.stderr)
         return None

From 973016102b4e82b331cf64ef8a2a63f9b1e3559b Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Tue, 16 Jun 2026 02:58:47 -0700
Subject: [PATCH 16/19] Frame sim preview captures on the full multi-env grid
 overview.

Set a raised world-frame camera via ViewerCfg and re-apply it through the
viewport controller before each capture so all 16 clones stay in frame.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../review_gui/sim_preview.py                 | 45 ++++++++++++++++---
 .../review_gui/streamlit_ui.py                |  2 +-
 2 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
index 36cebe0cc..97530b8fb 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
@@ -8,6 +8,7 @@
 from __future__ import annotations
 
 import argparse
+import math
 import sys
 import time
 import uuid
@@ -41,6 +42,39 @@ def _preview_args() -> argparse.Namespace:
     )
 
 
+def _overview_camera(
+    num_envs: int, env_spacing: float
+) -> tuple[tuple[float, float, float], tuple[float, float, float]]:
+    """Return (eye, lookat) in world frame for a high oblique view of the full env grid."""
+    cols = int(math.ceil(math.sqrt(num_envs)))
+    rows = int(math.ceil(num_envs / cols))
+    max_x = max((cols - 1) * env_spacing, 0.0)
+    max_y = max((rows - 1) * env_spacing, 0.0)
+    cx, cy = max_x * 0.5, max_y * 0.5
+    span = max(max_x, max_y, env_spacing)
+    # Oblique overview: close enough to fill the frame, still high enough for all clones.
+    height = span * 1.75 + env_spacing * 2.5
+    back = span * 1.4 + env_spacing * 2.0
+    side = span * 0.25
+    eye = (cx + side, cy - back, height)
+    target = (cx, cy, 0.75)
+    return eye, target
+
+
+def _apply_overview_camera(env, app, num_envs: int, env_spacing: float) -> None:
+    """Point the Kit viewport at the full multi-env grid (world frame)."""
+    eye, target = _overview_camera(num_envs, env_spacing)
+    unwrapped = env.unwrapped
+    vcc = getattr(unwrapped, "viewport_camera_controller", None)
+    if vcc is not None:
+        vcc.update_view_to_world()
+        vcc.update_view_location(eye=list(eye), lookat=list(target))
+    else:
+        unwrapped.sim.set_camera_view(eye, target)
+    for _ in range(20):
+        app.update()
+
+
 def _capture_viewport(app, cache_path: Path) -> bytes | None:
     from omni.kit.viewport.utility import capture_viewport_to_file, get_active_viewport  # noqa: PLC0415
 
@@ -88,14 +122,14 @@ def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
 
     env = None
     try:
-        # Match policy_runner: default Isaac Lab ViewerCfg (not task look-at-object offsets).
+        eye, target = _overview_camera(args.num_envs, args.env_spacing)
         env_cfg = builder.compose_manager_cfg()
-        env_cfg.viewer = ViewerCfg()
+        # World-frame overview (not task look-at-object) so all env clones are visible.
+        env_cfg.viewer = ViewerCfg(eye=eye, lookat=target, origin_type="world")
         env = builder.make_registered(env_cfg)
 
         obs, _ = env.reset()
-        for _ in range(10):
-            app.update()
+        _apply_overview_camera(env, app, args.num_envs, args.env_spacing)
 
         if _capture_viewport(app, first_path) is None:
             raise RuntimeError("failed to capture first-frame viewport screenshot")
@@ -104,8 +138,7 @@ def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
             action = policy.get_action(env, obs)
             obs, _, _, _, _ = env.step(action)
 
-        for _ in range(10):
-            app.update()
+        _apply_overview_camera(env, app, args.num_envs, args.env_spacing)
 
         if _capture_viewport(app, last_path) is None:
             raise RuntimeError("failed to capture last-frame viewport screenshot")
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
index 4d669d81f..d364822b9 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
@@ -593,7 +593,7 @@ def render_visualization_panel(validation: ValidationResult) -> None:
     st.caption(
         f"Runs link → to_arena_env → relation solver, then {NUM_STEPS} zero-action steps "
         f"with {NUM_ENVS} parallel envs at {ENV_SPACING_M} m spacing. "
-        "Viewport captures use the default scene camera (same as policy_runner)."
+        "Viewport captures use a world-frame overview of the full env grid."
     )
 
     if st.button(

From 5f1bce19389097dc9d314b8362d9c3efafa1b71c Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Tue, 16 Jun 2026 07:21:36 -0700
Subject: [PATCH 17/19] Fix repeat sim preview by closing env before resetting
 the USD stage.

Close gym env managers while SimulationContext is still valid, then
new_stage and pump Kit updates so stale cloner prims do not break the
next preview build in the sidecar.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../utils/isaaclab_utils/simulation_app.py    | 50 ++++++++++++++-----
 .../review_gui/sim_preview.py                 | 10 +++-
 2 files changed, 46 insertions(+), 14 deletions(-)

diff --git a/isaaclab_arena/utils/isaaclab_utils/simulation_app.py b/isaaclab_arena/utils/isaaclab_utils/simulation_app.py
index 4593986e5..7a4d4f264 100644
--- a/isaaclab_arena/utils/isaaclab_utils/simulation_app.py
+++ b/isaaclab_arena/utils/isaaclab_utils/simulation_app.py
@@ -97,23 +97,47 @@ def close_env_and_reset_sim(
     *,
     suppress_exceptions: bool = False,
     make_new_stage: bool = True,
+    app=None,
 ) -> None:
     """Tear down sim state and close a gym env so another can be built in the same SimApp.
 
-    Order matches :func:`isaaclab_arena.evaluation.eval_runner._close_env`: stop
-    :class:`~isaaclab.sim.SimulationContext`, open a fresh USD stage, then close
-    env managers and collect GPU garbage.
+    Close the gym env first so scene managers release prims while
+    :class:`~isaaclab.sim.SimulationContext` is still valid, then stop the timeline
+    and open a fresh USD stage.
     """
-    try:
-        teardown_simulation_app(suppress_exceptions=suppress_exceptions, make_new_stage=make_new_stage)
-    finally:
-        if env is not None:
-            if suppress_exceptions:
-                with suppress(Exception):
-                    env.close()
-            else:
-                env.close()
-        collect_garbage_and_clear_cuda_cache()
+    error_manager = suppress(Exception) if suppress_exceptions else nullcontext()
+
+    with error_manager:
+        if env is not None and not getattr(env.unwrapped, "_is_closed", True):
+            env.close()
+
+    # env.close() clears the singleton, but callers may omit env or close may fail partway.
+    with error_manager:
+        from isaaclab.sim import SimulationContext
+
+        sim = SimulationContext.instance()
+        if sim is not None:
+            sim._disable_app_control_on_stop_handle = True  # noqa: SLF001 (intentional private attr)
+            sim.stop()
+            sim.clear_instance()
+
+    with error_manager:
+        import omni.timeline
+
+        omni.timeline.get_timeline_interface().stop()
+
+    if make_new_stage:
+        with error_manager:
+            import omni.usd
+
+            omni.usd.get_context().new_stage()
+
+    if app is not None:
+        with error_manager:
+            for _ in range(20):
+                app.update()
+
+    collect_garbage_and_clear_cuda_cache()
 
 
 def reapply_viewer_cfg(env) -> None:
diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
index 97530b8fb..005bb7d8b 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
@@ -12,6 +12,7 @@
 import sys
 import time
 import uuid
+from contextlib import suppress
 from pathlib import Path
 from typing import Any
 
@@ -95,12 +96,16 @@ def _capture_viewport(app, cache_path: Path) -> bytes | None:
 
 def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
     """Link spec → arena env → relation solver → zero-action steps; capture viewport frames."""
+    import gymnasium as gym
     import yaml
 
     from isaaclab_arena.environments.arena_env_builder import ArenaEnvBuilder
     from isaaclab_arena.policy.zero_action_policy import ZeroActionPolicy, ZeroActionPolicyArgs
     from isaaclab_arena.utils.isaaclab_utils.simulation_app import close_env_and_reset_sim
 
+    # Drop any stale sim/scene state left from a prior preview in this sidecar.
+    close_env_and_reset_sim(suppress_exceptions=True, app=app)
+
     raw = yaml.safe_load(yaml_text)
     if not isinstance(raw, dict):
         raise ValueError(f"expected mapping, got {type(raw).__name__}")
@@ -157,4 +162,7 @@ def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
             "num_steps": NUM_STEPS,
         }
     finally:
-        close_env_and_reset_sim(env)
+        close_env_and_reset_sim(env, app=app)
+        with suppress(Exception):
+            if preview_name in gym.registry:
+                del gym.registry[preview_name]

From 1af0d55a1497f391983cd9caf710c708ddc699f4 Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Tue, 16 Jun 2026 07:43:16 -0700
Subject: [PATCH 18/19] Log sim preview phase timings before Kit scene spawn.

Emit flushed stderr milestones for teardown, spec linking, relation
solving, and gym.make so sidecar progress is visible during the silent
pre-spawn window.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../review_gui/sim_preview.py                 | 28 ++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
index 005bb7d8b..aad72af82 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/sim_preview.py
@@ -26,6 +26,14 @@
 ENV_SPACING_M = 1.5
 NUM_STEPS = 10
 
+# Placement pool size when preview uses resolve_on_reset=False (see ObjectPlacerParams).
+_PREVIEW_LAYOUTS_PER_ENV = 5
+
+
+def _preview_log(started_at: float, message: str) -> None:
+    elapsed = time.monotonic() - started_at
+    print(f"[sim_preview] +{elapsed:.1f}s {message}", file=sys.stderr, flush=True)
+
 
 def _preview_args() -> argparse.Namespace:
     return argparse.Namespace(
@@ -103,8 +111,12 @@ def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
     from isaaclab_arena.policy.zero_action_policy import ZeroActionPolicy, ZeroActionPolicyArgs
     from isaaclab_arena.utils.isaaclab_utils.simulation_app import close_env_and_reset_sim
 
+    started_at = time.monotonic()
+    _preview_log(started_at, "run_sim_preview started")
+
     # Drop any stale sim/scene state left from a prior preview in this sidecar.
     close_env_and_reset_sim(suppress_exceptions=True, app=app)
+    _preview_log(started_at, "cleared stale sim state")
 
     raw = yaml.safe_load(yaml_text)
     if not isinstance(raw, dict):
@@ -115,6 +127,7 @@ def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
     arena_env = graph_spec.to_arena_env()
     preview_name = f"{arena_env.name}_preview_{uuid.uuid4().hex[:8]}"
     arena_env.name = preview_name
+    _preview_log(started_at, f"linked spec → arena env ({preview_name})")
 
     args = _preview_args()
     builder = ArenaEnvBuilder(arena_env, args)
@@ -125,13 +138,24 @@ def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
     first_path = PREVIEW_CACHE_DIR / f"{preview_name}_{stamp}_first.png"
     last_path = PREVIEW_CACHE_DIR / f"{preview_name}_{stamp}_last.png"
 
+    pool_layouts = args.num_envs * _PREVIEW_LAYOUTS_PER_ENV
     env = None
     try:
         eye, target = _overview_camera(args.num_envs, args.env_spacing)
+        _preview_log(
+            started_at,
+            f"solving spatial relations ({args.num_envs} envs, {pool_layouts} layout pool)…",
+        )
+        t_relations = time.monotonic()
         env_cfg = builder.compose_manager_cfg()
+        _preview_log(started_at, f"relation solver finished ({time.monotonic() - t_relations:.1f}s)")
+
         # World-frame overview (not task look-at-object) so all env clones are visible.
         env_cfg.viewer = ViewerCfg(eye=eye, lookat=target, origin_type="world")
+        _preview_log(started_at, "spawning sim scene (gym.make)…")
+        t_spawn = time.monotonic()
         env = builder.make_registered(env_cfg)
+        _preview_log(started_at, f"sim scene ready ({time.monotonic() - t_spawn:.1f}s)")
 
         obs, _ = env.reset()
         _apply_overview_camera(env, app, args.num_envs, args.env_spacing)
@@ -149,8 +173,10 @@ def run_sim_preview(app, yaml_text: str) -> dict[str, Any]:
             raise RuntimeError("failed to capture last-frame viewport screenshot")
 
         print(
-            f"[sim_preview] captured {NUM_ENVS} envs @ {ENV_SPACING_M}m spacing, {NUM_STEPS} zero-action steps",
+            f"[sim_preview] captured {NUM_ENVS} envs @ {ENV_SPACING_M}m spacing, {NUM_STEPS} zero-action steps "
+            f"(total {time.monotonic() - started_at:.1f}s)",
             file=sys.stderr,
+            flush=True,
         )
         return {
             "ok": True,

From ce1d94b6595ad7c00b971968c287de8af7b3011c Mon Sep 17 00:00:00 2001
From: Qian Lin <qianl@nvidia.com>
Date: Tue, 16 Jun 2026 07:43:17 -0700
Subject: [PATCH 19/19] Skip redundant sidecar validation when launching sim
 preview.

Reuse the editor panel's ValidationResult on preview button click to
avoid a second validate_spec IPC round-trip on the same Streamlit rerun.

Signed-off-by: Qian Lin <qianl@nvidia.com>
---
 .../review_gui/streamlit_ui.py                  | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
index d364822b9..0d93e65f7 100644
--- a/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
+++ b/isaaclab_arena_examples/agentic_environment_generation/review_gui/streamlit_ui.py
@@ -358,11 +358,16 @@ def run_generation_pipeline(prompt: str) -> tuple[bool, str]:
     return True, "Spec generated and loaded into the YAML editor."
 
 
-def run_sim_preview_pipeline(yaml_text: str) -> tuple[bool, str]:
-    """Link, build, solve relations, and capture overview frames in the sidecar."""
-    validation = validate_yaml_text(yaml_text)
-    if not validation.is_valid:
-        return False, validation.error or "YAML must be valid before running sim preview."
+def run_sim_preview_pipeline(yaml_text: str, *, validation: ValidationResult | None = None) -> tuple[bool, str]:
+    """Link, build, solve relations, and capture overview frames in the sidecar.
+
+    When ``validation`` is already valid (e.g. from the editor panel on the same
+    rerun), skip the redundant sidecar ``validate_spec`` round-trip.
+    """
+    if validation is None or not validation.is_valid:
+        validation = validate_yaml_text(yaml_text)
+        if not validation.is_valid:
+            return False, validation.error or "YAML must be valid before running sim preview."
 
     sidecar = _ensure_sidecar()
     if sidecar is None:
@@ -606,7 +611,7 @@ def render_visualization_panel(validation: ValidationResult) -> None:
         with st.spinner(
             f"Building env, solving relations, and rolling out {NUM_STEPS} steps ({NUM_ENVS} envs @ {ENV_SPACING_M} m)…"
         ):
-            ok, message = run_sim_preview_pipeline(st.session_state["edited_text"])
+            ok, message = run_sim_preview_pipeline(st.session_state["edited_text"], validation=validation)
         if ok:
             st.success(message, icon="✅")
             st.rerun()