fix(hooks): don't emit permissionDecision 'defer' from question-preference-hook

'defer' is a real permissionDecision value in Claude Code, but it means
'pause this tool call and hand control back' and is honored in
print/non-interactive mode (interactive mode warns and ignores it).
The hook emitted it as its 'no opinion' outcome, which made every
AskUserQuestion call get deferred in non-interactive sessions (e.g. the
Claude Code desktop app): the question UI never rendered and AUQ
appeared completely broken after gstack setup registered the hook.

The neutral outcome for a PreToolUse hook is a silent exit 0 — so defer()
now emits nothing, or only additionalContext (without any
permissionDecision) when there is plan-tune memory context to inject.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

hosts/claude/hooks/question-preference-hook.ts

@@ -93,12 +93,23 @@ function readStdin(): Promise<string> {
 }
 
 function defer(additionalContext?: string): void {
-  const out: Record<string, unknown> = {
-    hookEventName: 'PreToolUse',
-    permissionDecision: 'defer',
-  };
-  if (additionalContext) out.additionalContext = additionalContext;
-  process.stdout.write(JSON.stringify({ hookSpecificOutput: out }));
+  // "No opinion" must be a SILENT exit 0 (optionally with additionalContext
+  // only), never an explicit `permissionDecision: 'defer'`. `defer` is a real
+  // value in Claude Code, but it means "pause this tool call and hand control
+  // back" and is honored in print/non-interactive mode. Emitting it here made
+  // every AskUserQuestion get deferred in non-interactive sessions (e.g. the
+  // desktop app) — the question UI never rendered. Interactive mode merely
+  // warns and ignores it.
+  if (additionalContext) {
+    process.stdout.write(
+      JSON.stringify({
+        hookSpecificOutput: {
+          hookEventName: 'PreToolUse',
+          additionalContext,
+        },
+      }),
+    );
+  }
   process.exit(0);
 }
 

test/memory-cache-injection.test.ts

@@ -91,7 +91,7 @@ describe('memory injection', () => {
         ],
       },
     });
-    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBeUndefined();
     expect(r.parsed?.hookSpecificOutput?.additionalContext).toContain('verbose explanations');
   });
 
@@ -115,7 +115,7 @@ describe('memory injection', () => {
         ],
       },
     });
-    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBeUndefined();
     expect(r.parsed?.hookSpecificOutput?.additionalContext).toBeUndefined();
   });
 
@@ -219,7 +219,7 @@ describe('per-session memory cache', () => {
         ],
       },
     });
-    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBeUndefined();
     expect(r.parsed?.hookSpecificOutput?.additionalContext).toBeUndefined();
   });
 });

test/question-preference-hook.test.ts

@@ -126,7 +126,7 @@ describe('defers (no enforcement)', () => {
       },
     });
     expect(r.status).toBe(0);
-    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBeUndefined();
   });
 
   test('marker missing → defer (D18)', () => {
@@ -141,7 +141,7 @@ describe('defers (no enforcement)', () => {
         ],
       },
     });
-    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBeUndefined();
   });
 
   test('always-ask preference → defer', () => {
@@ -156,7 +156,7 @@ describe('defers (no enforcement)', () => {
         ],
       },
     });
-    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBeUndefined();
   });
 
   test('empty stdin → defer (crash safety)', () => {
@@ -168,13 +168,13 @@ describe('defers (no enforcement)', () => {
     const res = spawnSync(HOOK, [], { env, input: '', encoding: 'utf-8' });
     expect(res.status).toBe(0);
     const parsed = JSON.parse(res.stdout || '{}');
-    expect(parsed.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(parsed.hookSpecificOutput?.permissionDecision).toBeUndefined();
   });
 
   test('non-AUQ tool_name → defer (defensive)', () => {
     writeProjectPref('test-q', 'never-ask');
     const r = runHook({ session_id: 's4', tool_name: 'Bash', tool_use_id: 'tu-4', tool_input: {} });
-    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBeUndefined();
   });
 });
 
@@ -219,7 +219,7 @@ describe('enforces never-ask preferences', () => {
         ],
       },
     });
-    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBeUndefined();
   });
 
   test('ambiguous recommendation (two labels) → defer (D2 refuse-on-ambiguous)', () => {
@@ -237,7 +237,7 @@ describe('enforces never-ask preferences', () => {
         ],
       },
     });
-    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBeUndefined();
   });
 
   test('no recommendation marker AND no prose match → defer', () => {
@@ -255,7 +255,7 @@ describe('enforces never-ask preferences', () => {
         ],
       },
     });
-    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBeUndefined();
   });
 });
 
@@ -317,7 +317,7 @@ describe('precedence: project wins over global (D8)', () => {
         ],
       },
     });
-    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBeUndefined();
   });
 });
 
@@ -443,7 +443,7 @@ describe('Conductor prose redirect', () => {
       undefined,
       CONDUCTOR,
     );
-    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(r.parsed?.hookSpecificOutput?.permissionDecision).toBeUndefined();
   });
 });
 

test/skill-e2e-plan-tune-cathedral.test.ts

@@ -296,7 +296,7 @@ describeIfSelected('PlanTune cathedral E2E: annotation', ['plan-tune-annotation'
     });
     expect(res.status).toBe(0);
     const parsed = JSON.parse(res.stdout || '{}');
-    expect(parsed.hookSpecificOutput?.permissionDecision).toBe('defer');
+    expect(parsed.hookSpecificOutput?.permissionDecision).toBeUndefined();
     expect(parsed.hookSpecificOutput?.additionalContext).toContain('verbose explanations');
   });
 });