fix: harden and de-slop the merged contribution batch

Follow-ups promised on merge, plus review findings on the batch itself:

- chat: task-tool output now respects the 512KiB render cap; quick-open
  icon is visible at rest on coarse pointers and reachable by keyboard
  (row keydown no longer swallows inner-button Enter/Space); composer
  inline-code decoration drops the metric-shifting padding; a btw fork
  send carries only the boundary instruction, never the promotion notice
- sync: cascade revert/unrevert aborts busy descendants, busy state is
  read from every child store at the moment of use; rule 9 documents
  redo clearing all descendant revert markers
- electron: renderer recovery keeps memory-eviction (a valid
  render-process-gone reason) and both windows share one
  attachRendererRecovery helper
- vscode: process registry is a thin re-export of the web module
  (provider-env-aliases precedent) with ordered register/unregister
  writes and an awaited close
- server/cli: managed-process registry takes injectable deps (fixes the
  unreaped-orphans ReferenceError), corrupt settings errors name the
  file, getWorktrees test restores console.warn
- tests: module-mock harnesses removed (AgentsSidebar, SettingsView
  mobile focus — behaviors stay live but uncovered, accepted trade),
  QuestionMarkdown asserts rendered DOM
- i18n: German gains the debug-panel request keys, Japanese/German drop
  removed worktree keys, Ukrainian unit spacing fixed
- changelog: Copilot AI Credits entries (main + VS Code)

packages/ui/src/lib/btw.test.ts

@@ -58,7 +58,7 @@ mock.module('@/sync/sync-refs', () => ({
   }),
 }));
 
-const { btwSessionTitle, startBtwSession, destroyBtwSession, promoteBtwSession, filterBtwTailMessages, findLastCompletedAssistantMessageID, BTW_BOUNDARY_INSTRUCTION } =
+const { btwSessionTitle, startBtwSession, destroyBtwSession, promoteBtwSession, filterBtwTailMessages, findLastCompletedAssistantMessageID, BTW_BOUNDARY_INSTRUCTION, BTW_PROMOTION_NOTICE, buildBtwSyntheticTexts } =
   await import('@/lib/btw');
 const { useBtwStore } = await import('@/stores/useBtwStore');
 
@@ -304,3 +304,24 @@ describe('promoteBtwSession', () => {
     expect(currentSessionSwitches).toEqual([]);
   });
 });
+
+describe('buildBtwSyntheticTexts', () => {
+  test('a send routed to an active fork carries only the boundary instruction', () => {
+    // Regression: a promoted parent that opens a new btw fork used to send the
+    // promotion notice into the fork alongside the boundary instruction, telling
+    // the fork both that btw constraints apply and that they no longer apply.
+    expect(buildBtwSyntheticTexts({ isBtwActive: true, isPromotedBtwSession: true }))
+      .toEqual([BTW_BOUNDARY_INSTRUCTION]);
+    expect(buildBtwSyntheticTexts({ isBtwActive: true, isPromotedBtwSession: false }))
+      .toEqual([BTW_BOUNDARY_INSTRUCTION]);
+  });
+
+  test('a promoted session with no active fork carries the promotion notice', () => {
+    expect(buildBtwSyntheticTexts({ isBtwActive: false, isPromotedBtwSession: true }))
+      .toEqual([BTW_PROMOTION_NOTICE]);
+  });
+
+  test('an ordinary session carries neither', () => {
+    expect(buildBtwSyntheticTexts({ isBtwActive: false, isPromotedBtwSession: false })).toEqual([]);
+  });
+});