feat(pty-runner): scope-gate question/auto-select detectors + observation flags

Two render-shape-anchored detectors (whitespace-squished, like the Pattern-4/5
collapsed-form handling): isScopeGateQuestionVisible requires the question text
PLUS option-body text (native AskUserQuestion renders numbered options, prose
fallback renders lettered — the option body appears in both; narration doesn't),
and isScopeGateAutoSelectVisible requires the announcement prefix PLUS the
selected-B token.

runPlanSkillObservation gains scopeGateQuestionObserved /
scopeGateAutoSelectObserved high-water flags (attached at every return path) so
paid smokes can assert gate behavior across the whole run instead of the lossy
2KB evidence tail. runPlanSkillFloorCheck no longer counts a scope-gate render
toward auqObserved (tail-scoped exclusion) — the floor measures FINDING-driven
questions, and the gate could fire inside the 3s pre-target window.

Unit fixtures pin clean/native/collapsed positives, narration negatives, and
the verbatim template announcement string (template rewording fails here first,
before the paid smokes degrade to vacuous asserts).

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

test/helpers/claude-pty-runner.unit.test.ts

@@ -28,6 +28,8 @@ import {
   isPermissionDialogVisible,
   isNumberedOptionListVisible,
   isProseAUQVisible,
+  isScopeGateQuestionVisible,
+  isScopeGateAutoSelectVisible,
   isPlanReadyVisible,
   parseNumberedOptions,
   classifyVisible,
@@ -194,6 +196,86 @@ describe('isNumberedOptionListVisible', () => {
   });
 });
 
+describe('scope-gate render detectors', () => {
+  // The verbatim announcement string from the plan-eng/plan-design SKILL.md
+  // templates. If the template rewording drifts, THIS fixture fails first —
+  // before the paid plan-mode smokes silently degrade to vacuous asserts.
+  const TEMPLATE_ANNOUNCEMENT =
+    'Scope gate: plan mode — auto-selected B (reviewing <target>).';
+
+  describe('isScopeGateQuestionVisible', () => {
+    test('matches the clean prose gate render (question + option bodies)', () => {
+      const sample = `
+What should I review?
+A) The current branch diff — the work in progress on this branch.
+B) A plan or design doc I'll paste or point you to.
+C) A specific file, directory, or path.
+Recommendation: A when a branch diff exists, otherwise B.
+`;
+      expect(isScopeGateQuestionVisible(sample)).toBe(true);
+    });
+
+    test('matches the native numbered render (no lettered markers)', () => {
+      const sample = `
+  What should I review?
+
+  ❯ 1. The current branch diff — the work in progress on this branch.
+    2. A plan or design doc I'll paste or point you to.
+    3. A specific file, directory, or path.
+`;
+      expect(isScopeGateQuestionVisible(sample)).toBe(true);
+    });
+
+    test('matches the PTY-collapsed render (stripAnsi squished spaces)', () => {
+      const sample = 'WhatshouldIreview?A)Thecurrentbranchdiff—theworkinprogress';
+      expect(isScopeGateQuestionVisible(sample)).toBe(true);
+    });
+
+    test('stays false on narration quoting only the question', () => {
+      const sample =
+        "Normally I'd ask 'What should I review?' but plan mode is active, so I'm proceeding.";
+      expect(isScopeGateQuestionVisible(sample)).toBe(false);
+    });
+
+    test('stays false on unrelated review prose', () => {
+      const sample = 'I will review the current branch diff and report findings.';
+      expect(isScopeGateQuestionVisible(sample)).toBe(false);
+    });
+  });
+
+  describe('isScopeGateAutoSelectVisible', () => {
+    test('matches the verbatim template announcement', () => {
+      expect(isScopeGateAutoSelectVisible(TEMPLATE_ANNOUNCEMENT)).toBe(true);
+    });
+
+    test('matches a real announcement with a concrete target', () => {
+      const sample =
+        'Scope gate: plan mode — auto-selected B (reviewing ~/.claude/plans/my-feature.md). Running the Design Doc Check next.';
+      expect(isScopeGateAutoSelectVisible(sample)).toBe(true);
+    });
+
+    test('matches the PTY-collapsed announcement', () => {
+      const sample = 'Scopegate:planmode—auto-selectedB(reviewingPLAN.md).';
+      expect(isScopeGateAutoSelectVisible(sample)).toBe(true);
+    });
+
+    test('stays false on narration about the behavior', () => {
+      const sample = "In plan mode I'd auto-select B and review the active plan.";
+      expect(isScopeGateAutoSelectVisible(sample)).toBe(false);
+    });
+
+    test('stays false on AUTO_DECIDE preamble output', () => {
+      const sample = 'Auto-decided scope question → B (your preference). Change with /plan-tune.';
+      expect(isScopeGateAutoSelectVisible(sample)).toBe(false);
+    });
+
+    test('stays false on a bare "selected B" without the announcement prefix', () => {
+      const sample = 'I selected B as the review target.';
+      expect(isScopeGateAutoSelectVisible(sample)).toBe(false);
+    });
+  });
+});
+
 describe('isProseAUQVisible', () => {
   test('matches 4 lettered options A) B) C) D) at line starts (plan-eng prose AUQ shape)', () => {
     const sample = `