ci(MMQA-1667): skip native builds when PR only changes E2E/performance tests

.github/actions/find-reusable-build/action.yml

@@ -55,6 +55,13 @@ inputs:
       until a run-specific status match is found.
     required: false
     default: '30'
+  main-branch-only:
+    description: >-
+      When true, only search the base branch (typically `main`) for reusable
+      builds. Used for PRs with test-only changes that should not compile fresh
+      native artifacts.
+    required: false
+    default: 'false'
 
 outputs:
   found:
@@ -86,6 +93,7 @@ runs:
         STATUS_CONTEXT: ${{ inputs.status-context }}
         MAX_CANDIDATES: ${{ inputs.max-candidates-per-branch }}
         MAX_CANDIDATES_CROSS_PR: ${{ inputs.max-candidates-cross-pr }}
+        MAIN_BRANCH_ONLY: ${{ inputs.main-branch-only }}
         HEAD_BRANCH: ${{ github.head_ref || github.ref_name }}
         HEAD_SHA: ${{ github.event.pull_request.head.sha || github.sha }}
         CURRENT_RUN_ID: ${{ github.run_id }}
@@ -101,6 +109,7 @@ runs:
             STATUS_CONTEXT,
             MAX_CANDIDATES,
             MAX_CANDIDATES_CROSS_PR,
+            MAIN_BRANCH_ONLY,
             HEAD_BRANCH,
             HEAD_SHA,
             CURRENT_RUN_ID,
@@ -155,25 +164,32 @@ runs:
           //                     lookups can never discover another PR's run
           //                     (GitHub filters `branch` against head_branch,
           //                     which is the PR source branch).
-          const tiers = [
-            {
+          const tiers = [];
+          const mainBranchOnly = MAIN_BRANCH_ONLY === 'true';
+
+          if (!mainBranchOnly) {
+            tiers.push({
               label: `same-branch (branch=${HEAD_BRANCH})`,
               params: { branch: HEAD_BRANCH, per_page: maxCandidates },
-            },
-          ];
-          if (BASE_BRANCH && BASE_BRANCH !== HEAD_BRANCH) {
+            });
+          }
+
+          if (BASE_BRANCH && (mainBranchOnly || BASE_BRANCH !== HEAD_BRANCH)) {
             tiers.push({
               label: `base-branch (branch=${BASE_BRANCH})`,
               params: { branch: BASE_BRANCH, per_page: maxCandidates },
             });
           }
-          tiers.push({
-            label: `cross-pr (event=pull_request, any branch, last ${maxCandidatesCrossPr} runs)`,
-            params: { event: 'pull_request', per_page: maxCandidatesCrossPr },
-            // Skip runs already visited by the same-branch tier to avoid
-            // wasting API calls on duplicates.
-            skipHeadBranch: HEAD_BRANCH,
-          });
+
+          if (!mainBranchOnly) {
+            tiers.push({
+              label: `cross-pr (event=pull_request, any branch, last ${maxCandidatesCrossPr} runs)`,
+              params: { event: 'pull_request', per_page: maxCandidatesCrossPr },
+              // Skip runs already visited by the same-branch tier to avoid
+              // wasting API calls on duplicates.
+              skipHeadBranch: HEAD_BRANCH,
+            });
+          }
 
           async function hasRunFingerprintStatus(sha, runId) {
             try {

.github/guidelines/E2E_DECISION_TREE.md

@@ -12,6 +12,7 @@ flowchart TD
     L2 -->|ignorable-only changes| NoBlock[No merge block]
     L2 -->|non-ignorable changes| Skip2[⛔️ Merge blocked]
     GR -->|PR ignorable-only changes| Ignorable[No E2E]
+    GR -->|PR test-only changes| TestOnly[E2E + Smart selection, reuse main builds]
     GR -->|PR has Android-only changes| Android[Android Build + Tests needed]
     GR -->|PR has iOS-only changes| iOS[iOS Build + Test needed]
     GR -->|PR other files changed| Both[Both Build + Tests needed]
@@ -25,6 +26,18 @@ flowchart TD
     CONF -->|no| AllTagsFallback[Run all E2E needed]
 ```
 
+## Test-only PR changes
+
+When a PR only changes E2E/performance test files (and other ignorable files), CI still runs Smart E2E Selection and the selected E2E/performance suites, but **does not compile fresh iOS/Android native builds**. Instead, it reuses the latest matching artifacts from `main`.
+
+The native build fingerprint for test-only PRs is computed from **`main` HEAD** (not the PR merge tree) so the lookup key matches completed `ci.yml` runs on `main`. Reuse tries GitHub Actions artifacts first, then the Cirrus `main` APK cache on Android.
+
+If `main` has new native-changing commits but its CI build has not finished yet, reuse lookup may miss — CI logs a warning and **falls back to a fresh native build** instead of failing the workflow. Performance E2E on test-only PRs resolves BrowserStack apps by `custom_id` prefix `MetaMask-Android-*-main-*` so only uploads from `main` are reused (not other branches or PRs).
+
+This applies when all changed files match `e2e_test_files` or `e2e_ignorable` filters in `.github/rules/filter-rules.yml`, with at least one E2E test file changed, and no E2E-relevant workflow files were modified.
+
+Use the `force-builds` label or `[force-builds]` commit tag to override reuse and compile fresh builds — including on test-only PRs that would otherwise require main-branch artifacts.
+
 ## E2E tests skipped by default on new PRs
 
 To save infra resources while waiting for static analysis findings and potential fixes/iterations:

.github/rules/filter-rules.yml

@@ -45,6 +45,34 @@ config_files: &config_files
 ci_files: &ci_files
   - '.github/**'
 
+# E2E / PERFORMANCE TEST FILES — do not require a fresh native build, but still
+# run E2E + Smart E2E selection when these are the only non-ignorable changes.
+e2e_test_files: &e2e_test_files
+  - 'tests/smoke/**'
+  - 'tests/regression/**'
+  - 'tests/performance/**'
+  - 'tests/smoke-appium/**'
+  - 'tests/flows/**'
+  - 'tests/page-objects/**'
+  - 'tests/selectors/**'
+  - 'tests/locators/**'
+  - 'tests/framework/**'
+  - 'tests/api-mocking/**'
+  - 'tests/docs/**'
+  - 'tests/scripts/**'
+  - 'tests/reporters/**'
+  - 'tests/tools/e2e-ai-analyzer/**'
+  - 'tests/playwright*.config.ts'
+  - 'tests/playwright.*.config.ts'
+  - 'tests/init.detox.js'
+  - 'tests/environment.detox.js'
+  - 'tests/jest.e2e.detox.config.js'
+  - 'tests/helpers.js'
+  - 'tests/tags.js'
+  - 'tests/tags.performance.js'
+  - 'tests/teams-config.js'
+  - 'wdio/**'
+
 # ALL IGNORABLE FILES - safe to skip E2E
 e2e_ignorable:
   - *documentation_files
@@ -54,6 +82,16 @@ e2e_ignorable:
   - *config_files
   - *ci_files
 
+# Union of ignorable + E2E test files for test-only change detection.
+e2e_test_or_ignorable:
+  - *documentation_files
+  - *asset_files
+  - *low_level_test_files
+  - *locale_translation_files
+  - *config_files
+  - *ci_files
+  - *e2e_test_files
+
 e2e_relevant_workflows:
   - '.github/workflows/ci.yml'
   - '.github/workflows/get-requirements.yml'

.github/scripts/browserstack-app-validation.cjs

@@ -0,0 +1,78 @@
+/**
+ * Validates BrowserStack API fields before they are written to GitHub Actions
+ * outputs or other local files.
+ */
+
+/** BrowserStack app URLs use the bs:// scheme with an opaque app hash. */
+const BROWSERSTACK_APP_URL_PATTERN = /^bs:\/\/[A-Za-z0-9]+$/;
+
+const WITH_SRP_CUSTOM_ID_PATTERN =
+  /^MetaMask-Android-With-SRP-[A-Za-z0-9._-]+-\d+$/;
+const WITHOUT_SRP_CUSTOM_ID_PATTERN =
+  /^MetaMask-Android-Without-SRP-[A-Za-z0-9._-]+-\d+$/;
+
+const MAIN_BRANCH_BROWSERSTACK_SLUG = 'main';
+const MAIN_WITH_SRP_CUSTOM_ID_PREFIX = `MetaMask-Android-With-SRP-${MAIN_BRANCH_BROWSERSTACK_SLUG}-`;
+const MAIN_WITHOUT_SRP_CUSTOM_ID_PREFIX = `MetaMask-Android-Without-SRP-${MAIN_BRANCH_BROWSERSTACK_SLUG}-`;
+
+/**
+ * @param {unknown} value
+ * @param {RegExp} pattern
+ * @param {string} label
+ * @returns {string}
+ */
+function assertMatchesPattern(value, pattern, label) {
+  if (typeof value !== 'string' || !pattern.test(value)) {
+    throw new Error(`Invalid ${label}`);
+  }
+  return value;
+}
+
+/**
+ * @param {unknown} value
+ * @param {string} label
+ * @returns {string}
+ */
+function assertBrowserStackAppUrl(value, label) {
+  return assertMatchesPattern(value, BROWSERSTACK_APP_URL_PATTERN, label);
+}
+
+/**
+ * @param {unknown} value
+ * @param {'with-srp' | 'without-srp'} kind
+ * @returns {string}
+ */
+function assertBrowserStackCustomId(value, kind) {
+  const pattern =
+    kind === 'with-srp'
+      ? WITH_SRP_CUSTOM_ID_PATTERN
+      : WITHOUT_SRP_CUSTOM_ID_PATTERN;
+  return assertMatchesPattern(value, pattern, `${kind} custom_id`);
+}
+
+/**
+ * @param {string} path
+ * @param {Record<string, string>} outputs
+ */
+function writeGithubOutputs(path, outputs) {
+  const lines = [];
+  for (const [key, value] of Object.entries(outputs)) {
+    if (value.includes('\n') || value.includes('\r')) {
+      throw new Error(`Refusing to write multiline GitHub output for ${key}`);
+    }
+    lines.push(`${key}=${value}`);
+  }
+  require('node:fs').appendFileSync(path, `${lines.join('\n')}\n`);
+}
+
+module.exports = {
+  BROWSERSTACK_APP_URL_PATTERN,
+  WITH_SRP_CUSTOM_ID_PATTERN,
+  WITHOUT_SRP_CUSTOM_ID_PATTERN,
+  MAIN_BRANCH_BROWSERSTACK_SLUG,
+  MAIN_WITH_SRP_CUSTOM_ID_PREFIX,
+  MAIN_WITHOUT_SRP_CUSTOM_ID_PREFIX,
+  assertBrowserStackAppUrl,
+  assertBrowserStackCustomId,
+  writeGithubOutputs,
+};

.github/scripts/browserstack-app-validation.test.ts

@@ -0,0 +1,66 @@
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+
+const {
+  assertBrowserStackAppUrl,
+  assertBrowserStackCustomId,
+  writeGithubOutputs,
+} = require('./browserstack-app-validation.cjs');
+
+describe('browserstack-app-validation', () => {
+  it('accepts valid BrowserStack app URLs', () => {
+    expect(assertBrowserStackAppUrl('bs://abc123DEF', 'test')).toBe(
+      'bs://abc123DEF',
+    );
+  });
+
+  it('rejects malformed BrowserStack app URLs', () => {
+    expect(() =>
+      assertBrowserStackAppUrl('https://evil.example/app', 'test'),
+    ).toThrow('Invalid test');
+    expect(() =>
+      assertBrowserStackAppUrl('bs://bad chars', 'test'),
+    ).toThrow('Invalid test');
+  });
+
+  it('accepts expected custom_id formats with branch slug', () => {
+    expect(
+      assertBrowserStackCustomId(
+        'MetaMask-Android-With-SRP-main-123',
+        'with-srp',
+      ),
+    ).toBe('MetaMask-Android-With-SRP-main-123');
+    expect(
+      assertBrowserStackCustomId(
+        'MetaMask-Android-Without-SRP-main-456',
+        'without-srp',
+      ),
+    ).toBe('MetaMask-Android-Without-SRP-main-456');
+    expect(
+      assertBrowserStackCustomId(
+        'MetaMask-Android-With-SRP-feature_x-789',
+        'with-srp',
+      ),
+    ).toBe('MetaMask-Android-With-SRP-feature_x-789');
+  });
+
+  it('rejects legacy custom_id formats without branch slug', () => {
+    expect(() =>
+      assertBrowserStackCustomId('MetaMask-Android-With-SRP-123', 'with-srp'),
+    ).toThrow('Invalid with-srp custom_id');
+  });
+
+  it('writes only validated single-line GitHub outputs', () => {
+    const outputPath = path.join(os.tmpdir(), `gh-output-${Date.now()}.txt`);
+    writeGithubOutputs(outputPath, {
+      found: 'true',
+      'with-srp-browserstack-url': 'bs://abc123',
+    });
+
+    expect(fs.readFileSync(outputPath, 'utf8')).toBe(
+      'found=true\nwith-srp-browserstack-url=bs://abc123\n',
+    );
+    fs.unlinkSync(outputPath);
+  });
+});