chore(renderer): tidy the comments and test hook noted in the pane isolation review

docs/superpowers/plans/2026-09-07-pane-isolation-review-notes.md

@@ -0,0 +1,171 @@
+### Task 2: Land Review B's three cosmetic notes from the #810 review
+
+**Files:**
+- Modify: `src/renderer/src/features/reply-to-selection/lib/selectionStash.ts:42`
+- Modify: `src/renderer/src/workspace/hook/helpers.ts:19-25` (the `EMPTY_RUNTIME` comment)
+- Modify: `src/renderer/src/workspace/tile-tree/TileLeaf/PaneHeader.tsx:163-174` (the related-agent status dot)
+- Modify: `src/renderer/src/workspace/tile-tree/TileLeaf/PaneHeader.phoneCoupling.renderer.test.tsx:61,77`
+- Create: `docs/superpowers/plans/2026-09-07-pane-isolation-review-notes.md` (this section)
+
+**Interfaces:**
+- Produces: a `data-related-status` attribute on the related-agent chip's status dot with values `'error' | 'attention' | 'running' | 'idle'`.
+
+Review B's notes, verbatim from the closed session: (1) "`selectionStash.ts:42` still names `setDraftVersion` in a WHY comment; the function is now `bumpDraftChanges`." (2) "The last sentence of the new `EMPTY_RUNTIME` comment in `helpers.ts` reads awkwardly." (3) "The new PaneHeader test detects the running state through a `.bg-accent` class query, which couples it to styling."
+
+- [ ] **Step 1: Create the worktree and commit the plan**
+
+```bash
+cd /Users/juliusolsson/Desktop/Development/agent-code
+git worktree add .worktrees/pane-isolation-review-notes -b chore/pane-isolation-review-notes origin/main
+cd .worktrees/pane-isolation-review-notes
+git submodule update --init && ln -s ../../node_modules node_modules
+# copy this Task 2 section into docs/superpowers/plans/2026-09-07-pane-isolation-review-notes.md
+git add docs/superpowers/plans/2026-09-07-pane-isolation-review-notes.md
+git commit -m "docs(renderer): plan the pane isolation review follow-ups
+
+Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
+Claude-Session: https://claude.ai/code/session_013SULm3ApxebET2a8eLxKHd"
+```
+
+- [ ] **Step 2: Fix the stale function name**
+
+In `src/renderer/src/features/reply-to-selection/lib/selectionStash.ts`, the comment currently reads:
+
+```
+//   quote" from last week would be a bug, not a feature). Runtime writes
+//   also bump setDraftVersion, which would dirty the autosave path on
+//   every mouse drag. codeBlockRegistry.ts sets the precedent for
+```
+
+Change the middle line to:
+
+```
+//   also call bumpDraftChanges, which would dirty the autosave path on
+```
+
+Confirm the name is current: `git grep -n "bumpDraftChanges" -- src/renderer/src/workspace/hook/actions/draft.ts` must list the declaration at line 39.
+
+- [ ] **Step 3: Rewrite the awkward invariant sentence**
+
+In `src/renderer/src/workspace/hook/helpers.ts`, replace the whole `EMPTY_RUNTIME` comment block (the lines from `// Missing sessions need a stable read-only fallback` through the line before `const EMPTY_RUNTIME = emptyRuntime()`) with:
+
+```ts
+// Missing sessions need a stable read-only fallback so merely asking for their
+// state cannot invalidate a memo boundary. Reducers still allocate their own.
+//
+// INVARIANT: this object is SHARED by every session that has no stored runtime
+// yet and must never be mutated in place. Update paths always build fresh
+// reducer-owned runtimes (spread + patch), so a `getRuntime()` result is only
+// ever read. An in-place edit here would leak into every runtime-less session
+// at once, because they all read this one object; the corruption would surface
+// only after one of them was created, which is the worst moment to debug it.
+```
+
+- [ ] **Step 4: Give the status dot a semantic hook and use it in the test**
+
+In `src/renderer/src/workspace/tile-tree/TileLeaf/PaneHeader.tsx`, the dot inside the related-agent chip is:
+
+```tsx
+                <span
+                  className={[
+                    'h-1.5 w-1.5 flex-shrink-0 rounded-full',
+                    attention === 'ERROR'
+                      ? 'bg-danger'
+                      : attention
+                        ? 'bg-warning'
+                        : running
+                          ? 'bg-accent'
+                          : 'bg-muted',
+                  ].join(' ')}
+                />
+```
+
+Add one attribute, computed from the same branches so the test and the color can never disagree:
+
+```tsx
+                <span
+                  // WHY a data attribute and not a role or aria-label: the dot
+                  // is decorative (the chip's `title` already carries the
+                  // relation and name for assistive tech), but tests need a
+                  // hook that does not depend on Tailwind class names. The
+                  // header row already uses `data-pane-header-row` for the
+                  // same reason, so this follows that precedent.
+                  data-related-status={
+                    attention === 'ERROR' ? 'error' : attention ? 'attention' : running ? 'running' : 'idle'
+                  }
+                  className={[
+                    'h-1.5 w-1.5 flex-shrink-0 rounded-full',
+                    attention === 'ERROR'
+                      ? 'bg-danger'
+                      : attention
+                        ? 'bg-warning'
+                        : running
+                          ? 'bg-accent'
+                          : 'bg-muted',
+                  ].join(' ')}
+                />
+```
+
+In `PaneHeader.phoneCoupling.renderer.test.tsx`, replace both occurrences of
+
+```ts
+    expect(chip!.querySelector('.bg-accent')).not.toBeNull()
+```
+
+with
+
+```ts
+    expect(chip!.querySelector('[data-related-status="running"]')).not.toBeNull()
+```
+
+- [ ] **Step 5: Run the affected tests and the type gate**
+
+```bash
+source /opt/homebrew/opt/nvm/nvm.sh && nvm use 24
+NODE_ENV=test npx vitest run --project renderer src/renderer/src/workspace/tile-tree/TileLeaf/PaneHeader.phoneCoupling.renderer.test.tsx
+npm run typecheck
+```
+Expected: 1 file / 3 tests passed; typecheck exit 0.
+
+- [ ] **Step 6: Commit, push, open the PR**
+
+```bash
+git add src/renderer/src/features/reply-to-selection/lib/selectionStash.ts src/renderer/src/workspace/hook/helpers.ts src/renderer/src/workspace/tile-tree/TileLeaf/PaneHeader.tsx src/renderer/src/workspace/tile-tree/TileLeaf/PaneHeader.phoneCoupling.renderer.test.tsx
+git commit -m "chore(renderer): tidy the comments and test hook noted in the pane isolation review
+
+The #810 review left three non-blocking notes: a comment naming a renamed
+function, an invariant sentence that read badly, and a regression test that
+detected the running state through a Tailwind class. The test now reads a
+data attribute computed from the same branches as the color, so styling
+changes cannot break it and the attribute cannot drift from the color.
+
+Refs #763
+
+Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
+Claude-Session: https://claude.ai/code/session_013SULm3ApxebET2a8eLxKHd"
+git push -u origin chore/pane-isolation-review-notes
+gh pr create --title "chore(renderer): tidy the comments and test hook noted in the pane isolation review" --body-file - <<'EOF'
+## Problem
+Review B of #810 left three non-blocking notes that were never actioned: a WHY comment in `selectionStash.ts` still named `setDraftVersion` (renamed to `bumpDraftChanges` in #810), the new `EMPTY_RUNTIME` invariant comment ended in a sentence that read badly, and the new `PaneHeader.phoneCoupling` test detected the running state through a `.bg-accent` class query.
+
+## Change
+- Comment names the current function.
+- Invariant comment rewritten; same invariant, plain sentences.
+- The related-agent status dot gets `data-related-status="error|attention|running|idle"` computed from the same branches as its color; the test queries that attribute.
+
+## Verification
+- `PaneHeader.phoneCoupling.renderer.test.tsx`: 3 tests pass on Node 24.
+- `npm run typecheck` clean.
+
+Refs #763
+
+🤖 Generated with [Claude Code](https://claude.com/claude-code)
+
+https://claude.ai/code/session_013SULm3ApxebET2a8eLxKHd
+EOF
+```
+
+CHECKPOINT: report the PR link; merge only on confirmation.
+
+---
+

src/renderer/src/features/reply-to-selection/lib/selectionStash.ts

@@ -39,7 +39,7 @@ import type { SessionId } from '@renderer/workspace/types'
 //   of those things — it is ephemeral and DOM-derived, and it must never
 //   be autosaved or rehydrated (resuming a session with a stale "pending
 //   quote" from last week would be a bug, not a feature). Runtime writes
-//   also bump setDraftVersion, which would dirty the autosave path on
+//   also call bumpDraftChanges, which would dirty the autosave path on
 //   every mouse drag. codeBlockRegistry.ts sets the precedent for
 //   DOM-derived data living in module scope.
 //

src/renderer/src/workspace/hook/helpers.ts

@@ -17,12 +17,12 @@ import { commandTargetSessionIdForState } from '@renderer/workspace/hook/selecto
 // Missing sessions need a stable read-only fallback so merely asking for their
 // state cannot invalidate a memo boundary. Reducers still allocate their own.
 //
-// INVARIANT: this object is SHARED across every missing session and must never
-// be mutated in place. Update paths always build fresh reducer-owned runtimes
-// (spread + patch), so a `getRuntime()` result is only ever read; an in-place
-// edit on it would silently contaminate every session that has no stored
-// runtime yet — until one session is created, then exactly one shared object
-// is shared by all of them at once (the worst possible time to corrupt it).
+// INVARIANT: this object is SHARED by every session that has no stored runtime
+// yet and must never be mutated in place. Update paths always build fresh
+// reducer-owned runtimes (spread + patch), so a `getRuntime()` result is only
+// ever read. An in-place edit here would leak into every runtime-less session
+// at once, because they all read this one object; the corruption would surface
+// only after one of them was created, which is the worst moment to debug it.
 const EMPTY_RUNTIME = emptyRuntime()
 
 // -----------------------------------------------------------------------------

src/renderer/src/workspace/tile-tree/TileLeaf/PaneHeader.phoneCoupling.renderer.test.tsx

@@ -58,7 +58,7 @@ describe('PaneHeader related-status store coupling', () => {
     )
     const chip = container.querySelector('button')
     expect(chip).not.toBeNull()
-    expect(chip!.querySelector('.bg-accent')).not.toBeNull()
+    expect(chip!.querySelector('[data-related-status="running"]')).not.toBeNull()
   })
 
   it('derives related status from the store when the key exists (desktop path)', () => {
@@ -74,6 +74,6 @@ describe('PaneHeader related-status store coupling', () => {
     )
     const chip = container.querySelector('button')
     expect(chip).not.toBeNull()
-    expect(chip!.querySelector('.bg-accent')).not.toBeNull()
+    expect(chip!.querySelector('[data-related-status="running"]')).not.toBeNull()
   })
 })

src/renderer/src/workspace/tile-tree/TileLeaf/PaneHeader.tsx

@@ -161,6 +161,15 @@ export function PaneHeader({
                 ].join(' ')}
               >
                 <span
+                  // WHY a data attribute and not a role or aria-label: the dot
+                  // is decorative (the chip's `title` already carries the
+                  // relation and name for assistive tech), but tests need a
+                  // hook that does not depend on Tailwind class names. The
+                  // header row already uses `data-pane-header-row` for the
+                  // same reason, so this follows that precedent.
+                  data-related-status={
+                    attention === 'ERROR' ? 'error' : attention ? 'attention' : running ? 'running' : 'idle'
+                  }
                   className={[
                     'h-1.5 w-1.5 flex-shrink-0 rounded-full',
                     attention === 'ERROR'