fix: keep saved running sessions sidebar-only on root boot

Root page loads should not automatically project a localStorage-saved running session into the active pane. Keep explicit /session/<sid> behavior unchanged while leaving the saved session discoverable from the sidebar.

(cherry picked from commit bb60cf21d911a84e285363bcecf46fb441181fb9)

static/boot.js

@@ -42,6 +42,17 @@ async function cancelSessionStream(session){
   if(typeof renderSessionList==='function') renderSessionList();
 }
 
+async function _savedSessionShouldStaySidebarOnly(sid){
+  if(!sid) return false;
+  try{
+    const data = await api(`/api/session?session_id=${encodeURIComponent(sid)}&messages=0&resolve_model=0`);
+    const session = data&&data.session;
+    return !!(session&&(session.active_stream_id||session.pending_user_message));
+  }catch(e){
+    return false;
+  }
+}
+
 // ── Mobile navigation ──────────────────────────────────────────────────────
 let _workspacePanelMode='closed'; // 'closed' | 'browse' | 'preview'
 
@@ -1346,9 +1357,18 @@ function applyBotName(){
   // Initialize reasoning chip on boot (fixes #1103 — chip hidden until session load)
   if(typeof fetchReasoningChip==='function') fetchReasoningChip();
   const urlSession=(typeof _sessionIdFromLocation==='function')?_sessionIdFromLocation():null;
-  const saved=urlSession||localStorage.getItem('hermes-webui-session');
+  const savedLocal=localStorage.getItem('hermes-webui-session');
+  const saved=urlSession||savedLocal;
   if(saved){
     try{
+      if(!urlSession&&savedLocal&&await _savedSessionShouldStaySidebarOnly(savedLocal)){
+        S.session=null; S.messages=[]; S.activeStreamId=null; S.busy=false;
+        S._bootReady=true;
+        syncTopbar();syncWorkspacePanelState();
+        $('emptyState').style.display='';
+        await renderSessionList();if(typeof startGatewaySSE==='function')startGatewaySSE();
+        return;
+      }
       await loadSession(saved);
       // If the restored session has no messages it is an ephemeral scratch pad —
       // treat the page as a fresh start rather than resuming a blank conversation.

tests/test_1694_root_saved_running_policy.py

@@ -0,0 +1,91 @@
+"""Regression tests for #1694 root boot policy around saved running sessions.
+
+The active pane is only a projection. A root `/` tab restored from
+``localStorage['hermes-webui-session']`` should not automatically project into a
+saved session that is still running, because that makes the new tab inherit the
+running pane's busy/stream state even though the user did not explicitly open
+that session.
+
+Explicit `/session/<sid>` reload remains different: it should still restore and
+reattach to the requested running session.
+"""
+
+from pathlib import Path
+
+
+REPO = Path(__file__).parent.parent
+BOOT_JS = (REPO / "static" / "boot.js").read_text(encoding="utf-8")
+
+
+def _boot_saved_session_block() -> str:
+    marker = "const urlSession="
+    start = BOOT_JS.find(marker)
+    assert start > 0, "boot saved-session restore block not found"
+    end_marker = "// no saved session"
+    end = BOOT_JS.find(end_marker, start)
+    assert end > start, "no-saved-session marker not found after restore block"
+    return BOOT_JS[start:end]
+
+
+def test_root_boot_distinguishes_url_session_from_localstorage_saved_session():
+    """Root restore and explicit URL restore must be separate decisions."""
+    block = _boot_saved_session_block()
+    assert "const savedLocal=" in block, (
+        "boot must keep the localStorage session separate from urlSession so "
+        "root `/` policy can differ from explicit `/session/<sid>` reload"
+    )
+    compact = block.replace(" ", "")
+    assert "constsaved=urlSession||savedLocal" in compact, (
+        "boot should still prefer explicit URL sessions over saved localStorage sessions"
+    )
+
+
+def test_root_saved_running_session_is_checked_before_load_session_projection():
+    """A saved running localStorage session should be detected before loadSession()."""
+    block = _boot_saved_session_block()
+    guard = "!urlSession&&savedLocal"
+    guard_pos = block.replace(" ", "").find(guard)
+    load_pos = block.find("await loadSession(saved)")
+    assert guard_pos >= 0, (
+        "root `/` boot must have a !urlSession && savedLocal guard for saved "
+        "running sessions before projecting them into the active pane"
+    )
+    assert load_pos >= 0, "loadSession(saved) call not found"
+    assert guard_pos < load_pos, (
+        "saved running-session root guard must run before loadSession(saved), "
+        "otherwise loadSession already projects the session into the active pane"
+    )
+    assert "_savedSessionShouldStaySidebarOnly" in block, (
+        "boot should delegate the saved-running metadata check to a named helper"
+    )
+
+
+def test_saved_running_session_helper_uses_metadata_only_and_runtime_markers():
+    """The helper should inspect metadata without loading messages or attaching SSE."""
+    helper_idx = BOOT_JS.find("async function _savedSessionShouldStaySidebarOnly")
+    assert helper_idx > 0, "saved-running root policy helper not found"
+    helper = BOOT_JS[helper_idx:helper_idx + 1200]
+    assert "/api/session?session_id=" in helper, (
+        "helper should inspect session metadata via /api/session before deciding"
+    )
+    assert "messages=0" in helper, "helper must avoid loading full messages"
+    assert "resolve_model=0" in helper, "helper must avoid unnecessary model resolution"
+    assert "active_stream_id" in helper, "helper must treat active_stream_id as running"
+    assert "pending_user_message" in helper, "helper must treat pending_user_message as running"
+    assert "loadSession(" not in helper, (
+        "helper must not call loadSession(), because that would already project "
+        "the saved session into the active pane"
+    )
+
+
+def test_root_saved_running_sidebar_only_path_renders_empty_state_and_sidebar():
+    """Skipping projection should still leave the app usable and sidebar visible."""
+    block = _boot_saved_session_block()
+    helper_pos = block.find("_savedSessionShouldStaySidebarOnly")
+    render_pos = block.find("await renderSessionList()", helper_pos)
+    empty_pos = block.find("$('emptyState').style.display=''", helper_pos)
+    return_pos = block.find("return;", helper_pos)
+    assert helper_pos >= 0, "saved-running helper call not found"
+    assert empty_pos > helper_pos, "sidebar-only path must show the empty state"
+    assert render_pos > helper_pos, "sidebar-only path must render the session list"
+    assert return_pos > render_pos, "sidebar-only path should return before loadSession(saved)"

tests/test_session_cross_tab_sync.py

@@ -41,7 +41,9 @@ def test_session_switch_updates_url_path_for_tab_local_anchor():
 
 def test_boot_prefers_url_session_over_local_storage_session():
     assert "const urlSession=(typeof _sessionIdFromLocation==='function')?_sessionIdFromLocation():null;" in BOOT_JS
-    assert "const saved=urlSession||localStorage.getItem('hermes-webui-session');" in BOOT_JS
+    assert "const savedLocal=localStorage.getItem('hermes-webui-session');" in BOOT_JS
+    assert "const saved=urlSession||savedLocal;" in BOOT_JS
+    assert "if(!urlSession&&savedLocal&&await _savedSessionShouldStaySidebarOnly(savedLocal))" in BOOT_JS
 
 
 def test_api_helper_resolves_against_document_base_not_session_path():