feat: add Gemini CLI E2E tests

Two E2E tests (gemini-discover-skill, gemini-review-findings) that
verify gstack skills work when invoked by the Gemini CLI. Follows
the same pattern as codex-e2e.test.ts — gated by EVALS=1 + binary
availability, diff-based selection via touchfiles, eval persistence.

- Add test/gemini-e2e.test.ts
- Add Gemini entries to E2E_TOUCHFILES and GLOBAL_TOUCHFILES
- Add test:gemini and test♊all scripts to package.json
- Add gemini-e2e.test.ts to test:evals, test:e2e, and ignore list

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

package.json

@@ -12,13 +12,15 @@
     "gen:skill-docs": "bun run scripts/gen-skill-docs.ts",
     "dev": "bun run browse/src/cli.ts",
     "server": "bun run browse/src/server.ts",
-    "test": "bun test browse/test/ test/ --ignore test/skill-e2e.test.ts --ignore test/skill-llm-eval.test.ts --ignore test/skill-routing-e2e.test.ts --ignore test/codex-e2e.test.ts",
+    "test": "bun test browse/test/ test/ --ignore test/skill-e2e.test.ts --ignore test/skill-llm-eval.test.ts --ignore test/skill-routing-e2e.test.ts --ignore test/codex-e2e.test.ts --ignore test/gemini-e2e.test.ts",
-    "test:evals": "EVALS=1 bun test test/skill-llm-eval.test.ts test/skill-e2e.test.ts test/skill-routing-e2e.test.ts test/codex-e2e.test.ts",
+    "test:evals": "EVALS=1 bun test test/skill-llm-eval.test.ts test/skill-e2e.test.ts test/skill-routing-e2e.test.ts test/codex-e2e.test.ts test/gemini-e2e.test.ts",
-    "test:evals:all": "EVALS=1 EVALS_ALL=1 bun test test/skill-llm-eval.test.ts test/skill-e2e.test.ts test/skill-routing-e2e.test.ts test/codex-e2e.test.ts",
+    "test:evals:all": "EVALS=1 EVALS_ALL=1 bun test test/skill-llm-eval.test.ts test/skill-e2e.test.ts test/skill-routing-e2e.test.ts test/codex-e2e.test.ts test/gemini-e2e.test.ts",
-    "test:e2e": "EVALS=1 bun test test/skill-e2e.test.ts test/skill-routing-e2e.test.ts test/codex-e2e.test.ts",
+    "test:e2e": "EVALS=1 bun test test/skill-e2e.test.ts test/skill-routing-e2e.test.ts test/codex-e2e.test.ts test/gemini-e2e.test.ts",
-    "test:e2e:all": "EVALS=1 EVALS_ALL=1 bun test test/skill-e2e.test.ts test/skill-routing-e2e.test.ts test/codex-e2e.test.ts",
+    "test:e2e:all": "EVALS=1 EVALS_ALL=1 bun test test/skill-e2e.test.ts test/skill-routing-e2e.test.ts test/codex-e2e.test.ts test/gemini-e2e.test.ts",
     "test:codex": "EVALS=1 bun test test/codex-e2e.test.ts",
     "test:codex:all": "EVALS=1 EVALS_ALL=1 bun test test/codex-e2e.test.ts",
+    "test:gemini": "EVALS=1 bun test test/gemini-e2e.test.ts",
+    "test:gemini:all": "EVALS=1 EVALS_ALL=1 bun test test/gemini-e2e.test.ts",
     "skill:check": "bun run scripts/skill-check.ts",
     "dev:skill": "bun run scripts/dev-skill.ts",
     "start": "bun run browse/src/server.ts",

test/gemini-e2e.test.ts

@@ -0,0 +1,173 @@
+/**
+ * Gemini CLI E2E tests — verify skills work when invoked by Gemini CLI.
+ *
+ * Spawns `gemini -p` with stream-json output in the repo root (where
+ * .agents/skills/ already exists), parses JSONL events, and validates
+ * structured results. Follows the same pattern as codex-e2e.test.ts.
+ *
+ * Prerequisites:
+ * - `gemini` binary installed (npm install -g @google/gemini-cli)
+ * - Gemini authenticated via ~/.gemini/ config or GEMINI_API_KEY env var
+ * - EVALS=1 env var set (same gate as Claude E2E tests)
+ *
+ * Skips gracefully when prerequisites are not met.
+ */
+
+import { describe, test, expect, afterAll } from 'bun:test';
+import { runGeminiSkill } from './helpers/gemini-session-runner';
+import type { GeminiResult } from './helpers/gemini-session-runner';
+import { EvalCollector } from './helpers/eval-store';
+import { selectTests, detectBaseBranch, getChangedFiles, GLOBAL_TOUCHFILES } from './helpers/touchfiles';
+import * as path from 'path';
+
+const ROOT = path.resolve(import.meta.dir, '..');
+
+// --- Prerequisites check ---
+
+const GEMINI_AVAILABLE = (() => {
+  try {
+    const result = Bun.spawnSync(['which', 'gemini']);
+    return result.exitCode === 0;
+  } catch { return false; }
+})();
+
+const evalsEnabled = !!process.env.EVALS;
+
+// Skip all tests if gemini is not available or EVALS is not set.
+const SKIP = !GEMINI_AVAILABLE || !evalsEnabled;
+
+const describeGemini = SKIP ? describe.skip : describe;
+
+// Log why we're skipping (helpful for debugging CI)
+if (!evalsEnabled) {
+  // Silent — same as Claude E2E tests, EVALS=1 required
+} else if (!GEMINI_AVAILABLE) {
+  process.stderr.write('\nGemini E2E: SKIPPED — gemini binary not found (install: npm i -g @google/gemini-cli)\n');
+}
+
+// --- Diff-based test selection ---
+
+// Gemini E2E touchfiles — keyed by test name, same pattern as Codex E2E
+const GEMINI_E2E_TOUCHFILES: Record<string, string[]> = {
+  'gemini-discover-skill':  ['.agents/skills/**', 'test/helpers/gemini-session-runner.ts'],
+  'gemini-review-findings': ['review/**', '.agents/skills/gstack-review/**', 'test/helpers/gemini-session-runner.ts'],
+};
+
+let selectedTests: string[] | null = null; // null = run all
+
+if (evalsEnabled && !process.env.EVALS_ALL) {
+  const baseBranch = process.env.EVALS_BASE
+    || detectBaseBranch(ROOT)
+    || 'main';
+  const changedFiles = getChangedFiles(baseBranch, ROOT);
+
+  if (changedFiles.length > 0) {
+    const selection = selectTests(changedFiles, GEMINI_E2E_TOUCHFILES, GLOBAL_TOUCHFILES);
+    selectedTests = selection.selected;
+    process.stderr.write(`\nGemini E2E selection (${selection.reason}): ${selection.selected.length}/${Object.keys(GEMINI_E2E_TOUCHFILES).length} tests\n`);
+    if (selection.skipped.length > 0) {
+      process.stderr.write(`  Skipped: ${selection.skipped.join(', ')}\n`);
+    }
+    process.stderr.write('\n');
+  }
+  // If changedFiles is empty (e.g., on main branch), selectedTests stays null -> run all
+}
+
+/** Skip an individual test if not selected by diff-based selection. */
+function testIfSelected(testName: string, fn: () => Promise<void>, timeout: number) {
+  const shouldRun = selectedTests === null || selectedTests.includes(testName);
+  (shouldRun ? test : test.skip)(testName, fn, timeout);
+}
+
+// --- Eval result collector ---
+
+const evalCollector = evalsEnabled && !SKIP ? new EvalCollector('e2e-gemini') : null;
+
+/** DRY helper to record a Gemini E2E test result into the eval collector. */
+function recordGeminiE2E(name: string, result: GeminiResult, passed: boolean) {
+  evalCollector?.addTest({
+    name,
+    suite: 'gemini-e2e',
+    tier: 'e2e',
+    passed,
+    duration_ms: result.durationMs,
+    cost_usd: 0, // Gemini doesn't report cost in USD; tokens are tracked
+    output: result.output?.slice(0, 2000),
+    turns_used: result.toolCalls.length, // approximate: tool calls as turns
+    exit_reason: result.exitCode === 0 ? 'success' : `exit_code_${result.exitCode}`,
+  });
+}
+
+/** Print cost summary after a Gemini E2E test. */
+function logGeminiCost(label: string, result: GeminiResult) {
+  const durationSec = Math.round(result.durationMs / 1000);
+  console.log(`${label}: ${result.tokens} tokens, ${result.toolCalls.length} tool calls, ${durationSec}s`);
+}
+
+// Finalize eval results on exit
+afterAll(async () => {
+  if (evalCollector) {
+    await evalCollector.finalize();
+  }
+});
+
+// --- Tests ---
+
+describeGemini('Gemini E2E', () => {
+
+  testIfSelected('gemini-discover-skill', async () => {
+    // Run Gemini in the repo root where .agents/skills/ exists
+    const result = await runGeminiSkill({
+      prompt: 'List any skills or instructions you have available. Just list the names.',
+      timeoutMs: 60_000,
+      cwd: ROOT,
+    });
+
+    logGeminiCost('gemini-discover-skill', result);
+
+    // Gemini should have produced some output
+    const passed = result.exitCode === 0 && result.output.length > 0;
+    recordGeminiE2E('gemini-discover-skill', result, passed);
+
+    expect(result.exitCode).toBe(0);
+    expect(result.output.length).toBeGreaterThan(0);
+    // The output should reference skills in some form
+    const outputLower = result.output.toLowerCase();
+    expect(
+      outputLower.includes('review') || outputLower.includes('gstack') || outputLower.includes('skill'),
+    ).toBe(true);
+  }, 120_000);
+
+  testIfSelected('gemini-review-findings', async () => {
+    // Run gstack-review skill via Gemini on this repo
+    const result = await runGeminiSkill({
+      prompt: 'Run the gstack-review skill on this repository. Review the current branch diff and report your findings.',
+      timeoutMs: 540_000,
+      cwd: ROOT,
+    });
+
+    logGeminiCost('gemini-review-findings', result);
+
+    // Should produce structured review-like output
+    const output = result.output;
+    const passed = result.exitCode === 0 && output.length > 50;
+    recordGeminiE2E('gemini-review-findings', result, passed);
+
+    expect(result.exitCode).toBe(0);
+    expect(output.length).toBeGreaterThan(50);
+
+    // Review output should contain some review-like content
+    const outputLower = output.toLowerCase();
+    const hasReviewContent =
+      outputLower.includes('finding') ||
+      outputLower.includes('issue') ||
+      outputLower.includes('review') ||
+      outputLower.includes('change') ||
+      outputLower.includes('diff') ||
+      outputLower.includes('clean') ||
+      outputLower.includes('no issues') ||
+      outputLower.includes('p1') ||
+      outputLower.includes('p2');
+    expect(hasReviewContent).toBe(true);
+  }, 600_000);
+});

test/helpers/touchfiles.ts

@@ -84,6 +84,10 @@ export const E2E_TOUCHFILES: Record<string, string[]> = {
   'codex-discover-skill':  ['codex/**', '.agents/skills/**', 'test/helpers/codex-session-runner.ts'],
   'codex-review-findings': ['review/**', '.agents/skills/gstack-review/**', 'codex/**', 'test/helpers/codex-session-runner.ts'],
 
+  // Gemini E2E (tests skills via Gemini CLI)
+  'gemini-discover-skill':  ['.agents/skills/**', 'test/helpers/gemini-session-runner.ts'],
+  'gemini-review-findings': ['review/**', '.agents/skills/gstack-review/**', 'test/helpers/gemini-session-runner.ts'],
+
   // QA bootstrap
   'qa-bootstrap': ['qa/**', 'browse/src/**', 'ship/**'],
 
@@ -160,6 +164,7 @@ export const LLM_JUDGE_TOUCHFILES: Record<string, string[]> = {
 export const GLOBAL_TOUCHFILES = [
   'test/helpers/session-runner.ts',
   'test/helpers/codex-session-runner.ts',
+  'test/helpers/gemini-session-runner.ts',
   'test/helpers/eval-store.ts',
   'test/helpers/llm-judge.ts',
   'scripts/gen-skill-docs.ts',