test: add e2e and LLM eval tests for SKILL.md setup block

- 3 Agent SDK e2e tests: happy path, NEEDS_SETUP, non-git-repo
- LLM eval: setup block clarity + actionability >= 4
- New error pattern: 'no such file or directory.*browse'

These tests catch the exact failure mode where agents can't discover
the browse binary via SKILL.md instructions.

test/skill-e2e.test.ts

@@ -73,6 +73,95 @@ Report what each command returned.`,
     expect(result.exitReason).toBe('success');
   }, 90_000);
 
+  test('agent discovers browse binary via SKILL.md setup block', async () => {
+    const ROOT = path.resolve(import.meta.dir, '..');
+    const skillMd = fs.readFileSync(path.join(ROOT, 'SKILL.md'), 'utf-8');
+    const setupStart = skillMd.indexOf('## SETUP');
+    const setupEnd = skillMd.indexOf('## IMPORTANT');
+    const setupBlock = skillMd.slice(setupStart, setupEnd);
+
+    // Guard: verify we extracted a valid setup block
+    expect(setupBlock).toContain('browse/dist/browse');
+
+    const result = await runSkillTest({
+      prompt: `Follow these instructions to find the browse binary and run a basic command.
+
+${setupBlock}
+
+After finding the binary, run: $B goto ${testServer.url}
+Then run: $B text
+Report whether it worked.`,
+      workingDirectory: tmpDir,
+      maxTurns: 10,
+      timeout: 60_000,
+    });
+
+    expect(result.browseErrors).toHaveLength(0);
+    expect(result.exitReason).toBe('success');
+  }, 90_000);
+
+  test('SKILL.md setup block shows NEEDS_SETUP when binary missing', async () => {
+    // Create a tmpdir with no browse binary
+    const emptyDir = fs.mkdtempSync(path.join(os.tmpdir(), 'skill-e2e-empty-'));
+
+    const ROOT = path.resolve(import.meta.dir, '..');
+    const skillMd = fs.readFileSync(path.join(ROOT, 'SKILL.md'), 'utf-8');
+    const setupStart = skillMd.indexOf('## SETUP');
+    const setupEnd = skillMd.indexOf('## IMPORTANT');
+    const setupBlock = skillMd.slice(setupStart, setupEnd);
+
+    const result = await runSkillTest({
+      prompt: `Follow these instructions exactly. Run the bash code block below and report what it outputs.
+
+${setupBlock}
+
+Report the exact output. Do NOT try to fix or install anything — just report what you see.`,
+      workingDirectory: emptyDir,
+      maxTurns: 5,
+      timeout: 30_000,
+    });
+
+    // Agent should see NEEDS_SETUP (not crash or guess wrong paths)
+    const allText = result.messages
+      .map((m: any) => JSON.stringify(m))
+      .join('\n');
+    expect(allText).toContain('NEEDS_SETUP');
+
+    // Clean up
+    try { fs.rmSync(emptyDir, { recursive: true, force: true }); } catch {}
+  }, 60_000);
+
+  test('SKILL.md setup block works outside git repo', async () => {
+    // Create a tmpdir outside any git repo
+    const nonGitDir = fs.mkdtempSync(path.join(os.tmpdir(), 'skill-e2e-nogit-'));
+
+    const ROOT = path.resolve(import.meta.dir, '..');
+    const skillMd = fs.readFileSync(path.join(ROOT, 'SKILL.md'), 'utf-8');
+    const setupStart = skillMd.indexOf('## SETUP');
+    const setupEnd = skillMd.indexOf('## IMPORTANT');
+    const setupBlock = skillMd.slice(setupStart, setupEnd);
+
+    const result = await runSkillTest({
+      prompt: `Follow these instructions exactly. Run the bash code block below and report what it outputs.
+
+${setupBlock}
+
+Report the exact output — either "READY: <path>" or "NEEDS_SETUP".`,
+      workingDirectory: nonGitDir,
+      maxTurns: 5,
+      timeout: 30_000,
+    });
+
+    // Should either find global binary (READY) or show NEEDS_SETUP — not crash
+    const allText = result.messages
+      .map((m: any) => JSON.stringify(m))
+      .join('\n');
+    expect(allText).toMatch(/READY|NEEDS_SETUP/);
+
+    // Clean up
+    try { fs.rmSync(nonGitDir, { recursive: true, force: true }); } catch {}
+  }, 60_000);
+
   test.todo('/qa quick completes without browse errors');
   test.todo('/ship completes without browse errors');
   test.todo('/review completes without browse errors');