fix(session): propagate error when subagent produces no text output

docs/superpowers/specs/2026-10-09-llm-panel-design.md

@@ -0,0 +1,136 @@
+# LLM Panel — Design Spec
+
+**Date:** 2026-10-09  
+**Status:** Approved for implementation
+
+## Goal
+
+Add a toggleable right-side panel that shows a live, unformatted transcript of
+LLM exchanges as they stream — text deltas, tool calls, reasoning blocks, and
+step boundaries — giving developers a debug view of the model's output separate
+from the conversational chat UI.
+
+## Non-goals
+
+- Showing the raw HTTP wire format (request bodies, headers, token counts).
+- Showing the full messages array sent to the model each call.
+- A third simultaneous panel (left sidebar + right LLM panel at the same time).
+
+## Architecture
+
+### New component: `internal/tui/llmpanel.go`
+
+`LLMPanel` is a bubbletea component with:
+
+```go
+type LLMEntry struct {
+    Kind    string // "text" | "tool" | "step" | "reasoning"
+    Role    string // "assistant" | "tool"
+    Content string
+}
+
+type LLMPanel struct {
+    entries  []LLMEntry
+    viewport viewport.Model
+    width    int
+    height   int
+    open     bool
+    atBottom bool
+}
+```
+
+- `Append(e LLMEntry)` adds an entry and scrolls to bottom if `atBottom`.
+- `View()` renders each entry with a dim role prefix (`▸ text`, `⚙ tool`, `──`, `~ thinking`) and no markdown processing.
+- Scrollable via `j/k` or arrow keys when the panel has focus (future scope; v1 is display-only, always scrolled to bottom).
+- Ring buffer: cap at 500 entries to prevent unbounded memory growth.
+
+### Layout changes: `internal/tui/layout.go`
+
+Add `llmPanelWidth int` and `hasLLMPanel bool` to the `layout` struct.
+
+`calculateLayout` gains a `llmPanelOpen bool` parameter alongside the existing
+`sidebarOpen bool`. The two are mutually exclusive: if both are true,
+`llmPanelOpen` wins (the user explicitly asked for the debug view).
+
+Panel width: fixed at 44 columns (wider than the sidebar's 28 — tool JSON needs room).
+
+`composeView` updated to:
+```
+[sidebar?] [chat] [llmPanel?]
+[prompt]
+[status]
+```
+
+When `hasLLMPanel` is true, `chatWidth = totalWidth - llmPanelWidth` and the
+panel is placed on the right via `JoinHorizontal`.
+
+Minimum terminal width to show the panel: 120 columns (same threshold as sidebar).
+
+### App integration: `app.go` / `app_update.go`
+
+- `App` gains `llmPanel LLMPanel` field.
+- `layout` calculation passes `a.llmPanel.IsOpen()` as the new arg; if LLM panel
+  open, `sidebarOpen` is forced false for layout purposes.
+- `forwardSSEMessages` routes the following existing messages to `llmPanel.Append`:
+  - `MessagePartDeltaMsg` with field `"text"` → `LLMEntry{Kind:"text", Role:"assistant", Content: delta}`
+  - `MessagePartUpdatedMsg` where part type is `"reasoning"` → `LLMEntry{Kind:"reasoning", ...}`
+  - `MessagePartUpdatedMsg` where part type is `"tool"` → `LLMEntry{Kind:"tool", Role:"tool", Content: formatted JSON}`
+  - `SessionStatusMsg` with status change to `busy/idle` → `LLMEntry{Kind:"step", Content: "── step start / step end ──"}`
+
+No new bus events, no server-side changes.
+
+### Keybinding: `internal/tui/keys.go`
+
+Add `ToggleLLMPanel key.Binding` with `ctrl+x l` (l for "log").
+
+```go
+ToggleLLMPanel key.Binding // ctrl+x l
+```
+
+### Slash command: `internal/tui/commands.go`
+
+Add `{Name: "llm-log", Description: "Toggle LLM stream panel", InPalette: true}`.
+
+Handler in `app_update.go` fires `LLMPanelToggleMsg{}` (new msg type in `msg.go`).
+
+## Data flow
+
+```
+processor_llm.go
+  └─ bus.Publish("session.text.delta" / "session.tool.begin" / ...)
+       └─ server SSE stream
+            └─ TUI api.Client.Subscribe()
+                 └─ run_handlers.go → MessagePartDeltaMsg / MessagePartUpdatedMsg
+                      └─ forwardSSEMessages()
+                           ├─ chat.go (existing)
+                           └─ llmpanel.Append() (new)
+```
+
+## Testing
+
+- `llmpanel_test.go`: unit tests for `Append` (ring buffer cap, entry ordering),
+  `View` rendering (role prefix present, no markdown leaking through), scroll
+  tracking.
+- `layout_test.go`: extend existing layout tests with `llmPanelOpen=true` cases;
+  verify mutual exclusion with sidebar.
+- No integration test changes required (no server-side changes).
+
+## Files touched
+
+| File | Change |
+|------|--------|
+| `internal/tui/llmpanel.go` | New — LLMPanel component |
+| `internal/tui/llmpanel_test.go` | New — unit tests |
+| `internal/tui/layout.go` | Add llmPanel slot to layout calc + composeView |
+| `internal/tui/msg.go` | Add `LLMPanelToggleMsg` |
+| `internal/tui/app.go` | Add `llmPanel` field, wire into NewApp |
+| `internal/tui/app_update.go` | Toggle handler, route events to panel |
+| `internal/tui/keys.go` | Add `ToggleLLMPanel` binding (`ctrl+x l`) |
+| `internal/tui/commands.go` | Add `llm-log` slash command |
+
+## Open questions (resolved)
+
+- **Raw vs structured data**: Use existing structured events (no server changes).
+- **Left vs right placement**: Right side, mutually exclusive with left sidebar.
+- **Width**: 44 columns (enough for tool JSON); fixed, not resizable in v1.
+- **Scroll**: v1 always follows bottom (auto-scroll); keyboard scroll is future scope.

go.mod

@@ -1,6 +1,6 @@
 module github.com/bobbyjohnstx/tinycode
 
-go 1.27.1
+go 1.25.0
 
 require (
 	github.com/charmbracelet/bubbles v1.0.0

internal/provider/discovery.go

@@ -106,9 +106,9 @@ func (d *Discovery) poll(ctx context.Context, ollamaURL, vllmURL, lmStudioURL st
 
 // shouldPoll reports whether a provider should be probed this tick.
 // Dormant providers stay eligible so a late-start daemon can reconnect.
+// Disabled providers are never polled.
 func (d *Discovery) shouldPoll(providerID string) bool {
-	_ = providerID
-	return true
+	return !d.registry.isFiltered(providerID)
 }
 
 // isDormant reports whether a provider was removed after consecutive failures.

internal/server/session_subagent.go

@@ -171,5 +171,11 @@ func (sm *SessionManager) RunSubagent(ctx context.Context, parentSessionID strin
 
 	response := strings.Join(texts, "\n\n")
 	slog.Info("subagent completed", "label", label, "parent", parentSessionID, "agent", agent, "responseLen", len(response))
+	if response == "" {
+		if result.Error != nil {
+			return "", fmt.Errorf("subagent produced no output: %w", result.Error)
+		}
+		return "(subagent completed but produced no text output)", nil
+	}
 	return response, nil
 }

internal/tui/prompt.go

@@ -14,6 +14,13 @@ import (
 
 var (
 	oscHexFragment = regexp.MustCompile(`^[0-9a-fA-F]{1,4}(/[0-9a-fA-F]{1,4}){1,2}\\?$`)
+	// Tail of a split OSC rgb: color response, e.g. "b:0000/0000/0000" or "gb/0000:0000:0000".
+	// Terminals vary in separator: xterm uses "rgb:R/G/B", others use "rgb/R:G:B".
+	// Occurs when the response arrives split across reads: "\033]10;rg" is consumed
+	// by the escape-byte check and the remaining tail leaks into the textarea.
+	// Terminal color responses always use exactly 4 hex digits per channel (16-bit).
+	// Requiring {4} avoids false-positives on user input like "/exit" (/e = 1 hex char).
+	oscRGBTail = regexp.MustCompile(`^[rgb]{0,3}[:\/][0-9a-fA-F]{4}([:\/][0-9a-fA-F]{4}){0,2}\\?$`)
 	// Core CPR payload after optional mangled CSI/OSC prefixes are stripped.
 	cprCore        = regexp.MustCompile(`^\d{0,4};\d{1,4}R$`)
 	cprCorePartial = regexp.MustCompile(`^\d{0,4};?\d{0,4}$`)
@@ -807,7 +814,7 @@ func isTerminalEscape(s string) bool {
 	if strings.Contains(s, "rgb:") || strings.HasPrefix(s, "]10;") || strings.HasPrefix(s, "]11;") {
 		return true
 	}
-	if oscHexFragment.MatchString(s) {
+	if oscHexFragment.MatchString(s) || oscRGBTail.MatchString(s) {
 		return true
 	}
 	if cprCore.MatchString(stripCPRPrefix(s)) {