test(perf): overhaul performance and memory baseline management

Comprehensive automation upgrades for performance and memory baselines. Includes GitHub Actions workflows for remote updates, automatic local comparisons against main, and git-ignored temporary baselines.

- Added update-baselines.yml GitHub Action to automate remote baseline upgrades efficiently in CI.
- Created scripts/run-perf-tests.js to wrap performance executions, safely stashing dirty alterations and gathering main-branch baselines locally when run without arguments.
- Enhanced PerfTestHarness and MemoryTestHarness to accommodate tolerance limits assertions safely.
- Updated test files to process TEMP_BASELINES_PATH environment variables, protecting tracked files clean during local evaluations.
- Formed docs/performance-and-memory-testing.md safely centrally detailing general strategies.
- Obsoleted folder files perf-tests/README.md, and memory-tests/README.md deleted altogether.
- Registered temporary baseline outputs inside .gitignore and updated scripts/clean.js safely for fast removals on npm run clean.

perf-tests/README.md

@@ -1,121 +0,0 @@
-# CPU Performance Integration Test Harness
-
-## Overview
-
-This directory contains performance/CPU integration tests for the Gemini CLI.
-These tests measure wall-clock time, CPU usage, and event loop responsiveness to
-detect regressions across key scenarios.
-
-CPU performance is inherently noisy, especially in CI. The harness addresses
-this with:
-
-- **IQR outlier filtering** — discards anomalous samples
-- **Median sampling** — takes N runs, reports the median after filtering
-- **Warmup runs** — discards the first run to mitigate JIT compilation noise
-- **15% default tolerance** — won't panic at slight regressions
-
-## Running
-
-```bash
-# Run tests (compare against committed baselines)
-npm run test:perf
-
-# Update baselines (after intentional changes)
-npm run test:perf:update-baselines
-
-# Verbose output
-VERBOSE=true npm run test:perf
-
-# Keep test artifacts for debugging
-KEEP_OUTPUT=true npm run test:perf
-```
-
-## How It Works
-
-### Measurement Primitives
-
-The `PerfTestHarness` class (in `packages/test-utils`) provides:
-
-- **`performance.now()`** — high-resolution wall-clock timing
-- **`process.cpuUsage()`** — user + system CPU microseconds (delta between
-  start/stop)
-- **`perf_hooks.monitorEventLoopDelay()`** — event loop delay histogram
-  (p50/p95/p99/max)
-
-### Noise Reduction
-
-1. **Warmup**: First run is discarded to mitigate JIT compilation artifacts
-2. **Multiple samples**: Each scenario runs N times (default 5)
-3. **IQR filtering**: Samples outside Q1−1.5×IQR and Q3+1.5×IQR are discarded
-4. **Median**: The median of remaining samples is used for comparison
-
-### Baseline Management
-
-Baselines are stored in `baselines.json` in this directory. Each scenario has:
-
-```json
-{
-  "cold-startup-time": {
-    "wallClockMs": 1234.5,
-    "cpuTotalUs": 567890,
-    "eventLoopDelayP99Ms": 12.3,
-    "timestamp": "2026-04-08T..."
-  }
-}
-```
-
-Tests fail if the measured value exceeds `baseline × 1.15` (15% tolerance).
-
-To recalibrate after intentional changes:
-
-```bash
-npm run test:perf:update-baselines
-# then commit baselines.json
-```
-
-### Report Output
-
-After all tests, the harness prints an ASCII summary:
-
-```
-═══════════════════════════════════════════════════
-         PERFORMANCE TEST REPORT
-═══════════════════════════════════════════════════
-
-cold-startup-time:   1234.5 ms (Baseline: 1200.0 ms, Delta: +2.9%) ✅
-idle-cpu-usage:         2.1 %  (Baseline: 2.0 %, Delta: +5.0%)     ✅
-skill-loading-time:  1567.8 ms (Baseline: 1500.0 ms, Delta: +4.5%) ✅
-```
-
-## Architecture
-
-```
-perf-tests/
-├── README.md              ← you are here
-├── baselines.json         ← committed baseline values
-├── globalSetup.ts         ← test environment setup
-├── perf-usage.test.ts     ← test scenarios
-├── perf.*.responses       ← fake API responses per scenario
-├── tsconfig.json          ← TypeScript config
-└── vitest.config.ts       ← vitest config (serial, isolated)
-
-packages/test-utils/src/
-├── perf-test-harness.ts   ← PerfTestHarness class
-└── index.ts               ← re-exports
-```
-
-## CI Integration
-
-These tests are **excluded from `preflight`** and designed for nightly CI:
-
-```yaml
-- name: Performance regression tests
-  run: npm run test:perf
-```
-
-## Adding a New Scenario
-
-1. Add a fake response file: `perf.<scenario-name>.responses`
-2. Add a test case in `perf-usage.test.ts` using `harness.runScenario()`
-3. Run `npm run test:perf:update-baselines` to establish initial baseline
-4. Commit the updated `baselines.json`

perf-tests/perf-usage.test.ts

@@ -5,13 +5,18 @@
  */
 
 import { describe, it, beforeAll, afterAll } from 'vitest';
-import { TestRig, PerfTestHarness } from '@google/gemini-cli-test-utils';
+import {
+  TestRig,
+  PerfTestHarness,
+  resolvePerfBaselinesPath,
+} from '@google/gemini-cli-test-utils';
 import { join, dirname } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { existsSync, readFileSync } from 'node:fs';
 
 const __dirname = dirname(fileURLToPath(import.meta.url));
-const BASELINES_PATH = join(__dirname, 'baselines.json');
+const MACHINE_FAMILY = process.env['PERF_MACHINE_FAMILY'];
+const BASELINES_PATH = resolvePerfBaselinesPath(__dirname, MACHINE_FAMILY);
 const UPDATE_BASELINES = process.env['UPDATE_PERF_BASELINES'] === 'true';
 const TOLERANCE_PERCENT = 15;
 
@@ -28,6 +33,7 @@ describe('CPU Performance Tests', () => {
       defaultTolerancePercent: TOLERANCE_PERCENT,
       sampleCount: SAMPLE_COUNT,
       warmupCount: WARMUP_COUNT,
+      machineFamily: MACHINE_FAMILY,
     });
   });