feat(evals): seedSkills opt-in for PTY slash-command tests + tripwire

Wire ClaudePtyOptions.seedSkills through launchClaudePty: when set (and
hermetic, and no per-test CLAUDE_CONFIG_DIR override), the child gets
hermeticSkillsConfigDir() so typed /skill slash commands resolve instead
of dying as Unknown command before any model turn. Opted in at the three
runPlanSkill* helpers and the four direct-launch slash-command tests
(plan-design-with-ui, plan-ceo-mode-routing, autoplan-chain,
ship-idempotency).

New static tripwire (test/pty-skill-seeding-wiring.test.ts): any test
file that sends a slash command over the PTY must route through a
runPlanSkill* helper or pass seedSkills: true — an unseeded slash-command
test spends money and measures nothing. hermetic-wiring.test.ts now
blesses the repo-tree seeding path explicitly (config dir under runRoot,
symlinks into the repo checkout, never operator ~/.claude).

The CI "Register gstack skills for PTY smoke" step keeps a keep-me note:
container cross-mount symlinks defeat the TUI scanner and HOME is not
hermeticized, so the real-file copies there must survive this change.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
(cherry picked from commit 63c52269daaffb833b3105ea9b4b99be6df8fec7)

test/pty-skill-seeding-wiring.test.ts

@@ -0,0 +1,77 @@
+/**
+ * Static-grep tripwire for PTY slash-command skill seeding. Free tier — no API.
+ *
+ * The default hermetic config dir registers NO skills, so a PTY test that
+ * TYPES a /skill slash command against it gets "Unknown command" before any
+ * model turn — the test still runs, still spends money, and measures nothing.
+ * Every test file that sends a slash command over the PTY must therefore
+ * either route through a runPlanSkill* helper (which opts in for you) or pass
+ * `seedSkills: true` in its own launchClaudePty options.
+ *
+ * Pattern mirrors test/hermetic-wiring.test.ts: read sources as text, assert
+ * invariants on their contents. Brittle by design — changing the seeding
+ * wiring must force the author to look here.
+ */
+
+import { describe, test, expect } from 'bun:test';
+import * as fs from 'fs';
+import * as path from 'path';
+
+const ROOT = path.resolve(new URL(import.meta.url).pathname, '..', '..');
+
+/** A PTY send whose payload starts with a slash command (`/name`, optionally
+ * followed by `\r`, whitespace, or the closing quote). A second slash right
+ * after the name (a file path like '/tmp/x') does NOT match. */
+const SLASH_SEND = /\.send\(\s*(['"`])\/[a-z][a-z0-9-]*(\\r|\s|\1)/;
+
+const RUN_PLAN_HELPER = /\brunPlanSkill(Observation|Counting|FloorCheck)\s*\(/;
+
+function testFiles(dir: string): string[] {
+  const out: string[] = [];
+  for (const entry of fs.readdirSync(dir, { withFileTypes: true })) {
+    const full = path.join(dir, entry.name);
+    if (entry.isDirectory()) out.push(...testFiles(full));
+    else if (entry.name.endsWith('.test.ts')) out.push(full);
+  }
+  return out;
+}
+
+describe('PTY skill-seeding tripwire', () => {
+  test('every slash-command PTY test seeds skills (helper or seedSkills: true)', () => {
+    const offenders: string[] = [];
+    for (const full of testFiles(path.join(ROOT, 'test'))) {
+      if (path.basename(full) === 'pty-skill-seeding-wiring.test.ts') continue;
+      const src = fs.readFileSync(full, 'utf-8');
+      const lines = src.split('\n');
+      const sendLine = lines.findIndex((l) => SLASH_SEND.test(l));
+      if (sendLine === -1) continue;
+      if (RUN_PLAN_HELPER.test(src)) continue;
+      if (src.includes('seedSkills: true')) continue;
+      offenders.push(`${path.relative(ROOT, full)}:${sendLine + 1}`);
+    }
+    expect(
+      offenders,
+      'These tests type a /skill slash command into a hermetic PTY child that has ' +
+        'no skills registered — claude rejects it as Unknown command and the test ' +
+        'measures nothing. Pass seedSkills: true to launchClaudePty (or route ' +
+        'through a runPlanSkill* helper): ' + offenders.join(', '),
+    ).toEqual([]);
+  });
+
+  test('the runPlanSkill* helpers all opt in via seedSkills: true', () => {
+    // The helper family types slash commands on behalf of ~20 test files;
+    // dropping the opt-in there silently un-measures all of them at once.
+    const src = fs.readFileSync(path.join(ROOT, 'test/helpers/claude-pty-runner.ts'), 'utf-8');
+    const optIns = src.match(/seedSkills: true/g) ?? [];
+    expect(optIns.length).toBeGreaterThanOrEqual(3);
+  });
+
+  test('launchClaudePty wires seedSkills to hermeticSkillsConfigDir()', () => {
+    const src = fs.readFileSync(path.join(ROOT, 'test/helpers/claude-pty-runner.ts'), 'utf-8');
+    // Gated on hermetic (EVALS_HERMETIC=0 must keep the operator config) and
+    // on the per-test env override (explicit CLAUDE_CONFIG_DIR wins).
+    const wired =
+      /if\s*\(opts\.seedSkills && hermetic && !opts\.env\?\.CLAUDE_CONFIG_DIR\)\s*\{\s*\n\s*childEnv\.CLAUDE_CONFIG_DIR = hermeticSkillsConfigDir\(\);/.test(src);
+    expect(wired, 'launchClaudePty must set CLAUDE_CONFIG_DIR from hermeticSkillsConfigDir() when seedSkills && hermetic && no per-test override').toBe(true);
+  });
+});