feat: test failure ownership triage — see something say something

Adds two new preamble sections to all gstack skills:
- Repo Ownership Mode: explains solo vs collaborative behavior
- See Something, Say Something: proactive issue flagging principle

Adds {{TEST_FAILURE_TRIAGE}} template variable (opt-in, used by /ship):
- Classifies test failures as in-branch vs pre-existing
- Solo mode defaults to "investigate and fix now"
- Collaborative mode offers "blame + assign GitHub issue" option
- Also offers P0 TODO and skip options

/ship Step 3 now triages test failures instead of hard-stopping on all
failures. In-branch failures still block shipping. Pre-existing failures
get user-directed triage based on repo mode.

Adds P2 TODO for gstack notes system (deferred lightweight reminder).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

test/helpers/touchfiles.ts

@@ -64,7 +64,7 @@ export const E2E_TOUCHFILES: Record<string, string[]> = {
   'plan-eng-review-artifact':  ['plan-eng-review/**'],
 
   // Ship
-  'ship-base-branch': ['ship/**'],
+  'ship-base-branch': ['ship/**', 'bin/gstack-repo-mode'],
 
   // Retro
   'retro':             ['retro/**'],
@@ -84,7 +84,7 @@ export const E2E_TOUCHFILES: Record<string, string[]> = {
   'qa-bootstrap': ['qa/**', 'browse/src/**', 'ship/**'],
 
   // Ship coverage audit
-  'ship-coverage-audit': ['ship/**'],
+  'ship-coverage-audit': ['ship/**', 'bin/gstack-repo-mode'],
 
   // Design
   'design-consultation-core':     ['design-consultation/**'],

test/skill-validation.test.ts

@@ -1324,3 +1324,58 @@ describe('Codex skill validation', () => {
     }
   });
 });
+
+// --- Repo mode and test failure triage validation ---
+
+describe('Repo mode preamble validation', () => {
+  test('generated SKILL.md preamble contains REPO_MODE output', () => {
+    const content = fs.readFileSync(path.join(ROOT, 'SKILL.md'), 'utf-8');
+    expect(content).toContain('REPO_MODE:');
+    expect(content).toContain('gstack-repo-mode');
+  });
+
+  test('generated SKILL.md contains See Something Say Something section', () => {
+    const content = fs.readFileSync(path.join(ROOT, 'SKILL.md'), 'utf-8');
+    expect(content).toContain('See Something, Say Something');
+    expect(content).toContain('REPO_MODE');
+    expect(content).toContain('solo');
+    expect(content).toContain('collaborative');
+  });
+});
+
+describe('Test failure triage in ship skill', () => {
+  test('ship/SKILL.md contains Test Failure Ownership Triage', () => {
+    const content = fs.readFileSync(path.join(ROOT, 'ship', 'SKILL.md'), 'utf-8');
+    expect(content).toContain('Test Failure Ownership Triage');
+  });
+
+  test('ship/SKILL.md triage uses git diff for classification', () => {
+    const content = fs.readFileSync(path.join(ROOT, 'ship', 'SKILL.md'), 'utf-8');
+    expect(content).toContain('git diff origin/<base>...HEAD --name-only');
+  });
+
+  test('ship/SKILL.md triage has solo and collaborative paths', () => {
+    const content = fs.readFileSync(path.join(ROOT, 'ship', 'SKILL.md'), 'utf-8');
+    expect(content).toContain('REPO_MODE');
+    expect(content).toContain('solo');
+    expect(content).toContain('collaborative');
+    expect(content).toContain('Investigate and fix now');
+    expect(content).toContain('Add as P0 TODO');
+  });
+
+  test('ship/SKILL.md triage has GitHub issue assignment for collaborative mode', () => {
+    const content = fs.readFileSync(path.join(ROOT, 'ship', 'SKILL.md'), 'utf-8');
+    expect(content).toContain('gh issue create');
+    expect(content).toContain('--assignee');
+  });
+
+  test('{{TEST_FAILURE_TRIAGE}} placeholder is fully resolved in ship/SKILL.md', () => {
+    const content = fs.readFileSync(path.join(ROOT, 'ship', 'SKILL.md'), 'utf-8');
+    expect(content).not.toContain('{{TEST_FAILURE_TRIAGE}}');
+  });
+
+  test('ship/SKILL.md uses in-branch language for stop condition', () => {
+    const content = fs.readFileSync(path.join(ROOT, 'ship', 'SKILL.md'), 'utf-8');
+    expect(content).toContain('In-branch test failures');
+  });
+});