test(ios): own snapshot differential on macOS

.github/workflows/macos.yml

@@ -70,6 +70,10 @@ jobs:
         uses: ./.github/actions/run-gate
         with: { gate: macos-coverage }
 
+      - name: Run iOS snapshot Swift/TypeScript differential
+        uses: ./.github/actions/run-gate
+        with: { gate: ios-snapshot-differential }
+
       - name: Restore and build macOS XCTest runner
         uses: ./.github/actions/setup-apple-runner-build
         with:

package.json

@@ -117,6 +117,7 @@
     "maestro:conformance": "node --experimental-strip-types scripts/node-test-tmpdir.ts --experimental-strip-types --test scripts/maestro-conformance/format-generated-json.test.mjs packages/maestro/test/conformance/verify.test.ts packages/maestro/test/conformance/differential/engine-process.test.ts packages/maestro/test/conformance/differential/report-output.test.ts packages/maestro/test/conformance/differential/run.test.ts packages/maestro/test/conformance/differential/invariants.test.ts",
     "maestro:conformance:regenerate": "node --experimental-strip-types scripts/maestro-conformance/regenerate.mjs",
     "maestro:conformance:differential": "node --experimental-strip-types packages/maestro/test/conformance/differential/run.ts",
+    "test:ios-snapshot-differential": "node --experimental-strip-types scripts/node-test-tmpdir.ts --experimental-strip-types --test scripts/ios-snapshot-differential.test.ts",
     "size": "node scripts/size-report.mjs",
     "perf": "node --experimental-strip-types scripts/perf/run.ts",
     "mutation:run": "node --experimental-strip-types scripts/mutation/run.ts",

scripts/check-affected/checks.ts

@@ -46,6 +46,12 @@ export const CHECK_CATALOG: readonly CheckSpec[] = [
   gate('package', 'Published package (publint, attw, clean-install resolution)', 'check:package'),
   gate('integration-node', 'Node integration smoke', 'test:integration:node'),
   gate('macos-coverage', 'macOS command coverage manifest', 'test:integration:macos-coverage'),
+  gate(
+    'ios-snapshot-differential',
+    'iOS snapshot Swift/TypeScript differential',
+    'test:ios-snapshot-differential',
+    false,
+  ),
   {
     id: 'vitest-related',
     label: 'Tests related by Vitest module graph',

scripts/check-affected/model.ts

@@ -46,6 +46,7 @@ export type CheckId =
   | 'provider-integration'
   | 'integration-node'
   | 'macos-coverage'
+  | 'ios-snapshot-differential'
   | 'integration-progress'
   | 'swift-runner-ios'
   | 'swift-runner-macos'
@@ -105,6 +106,7 @@ export const ALL_CHECKS: readonly CheckId[] = [
   // run before the related-project workload heats the host.
   'integration-node',
   'macos-coverage',
+  'ios-snapshot-differential',
   'vitest-related',
   'unit',
   'unit-ci',
@@ -435,6 +437,15 @@ const BUILD_OWNERSHIP: ReadonlyArray<{
   detail: string;
   owns: (file: string) => boolean;
 }> = [
+  {
+    check: 'ios-snapshot-differential',
+    rule: 'own:ios-snapshot-differential',
+    detail: 'the required macOS lane runs the Swift/TypeScript snapshot differential',
+    owns: (file) =>
+      file.startsWith('packages/capture-kit/src/ios-snapshot-engine/') ||
+      file.startsWith('apple/snapshot-presentation/') ||
+      file === 'contracts/fixtures/ios-snapshot-engine-conformance.json',
+  },
   // Both platform builds compile the same runner sources, and each is a separate
   // gate in a separate lane, so a Swift change owns both.
   {

scripts/ios-snapshot-differential.test.ts

@@ -1,14 +1,14 @@
 import assert from 'node:assert/strict';
+import { test } from 'node:test';
 import fc from 'fast-check';
-import { test } from 'vitest';
 import {
   compareDifferentialCases,
   swiftToolchainAvailable,
   SWIFT_RUN_TIMEOUT_MS,
   writeDifferentialFailureArtifact,
-} from './conformance-harness.ts';
-import { differentialBatchArbitrary } from './conformance-generator.ts';
-import { readIosSnapshotEngineFixture } from './conformance-fixture.ts';
+} from '../packages/capture-kit/src/ios-snapshot-engine/conformance-harness.ts';
+import { differentialBatchArbitrary } from '../packages/capture-kit/src/ios-snapshot-engine/conformance-generator.ts';
+import { readIosSnapshotEngineFixture } from '../packages/capture-kit/src/ios-snapshot-engine/conformance-fixture.ts';
 
 type DifferentialCase = Parameters<typeof compareDifferentialCases>[0][number];
 
@@ -16,9 +16,11 @@ const FUZZ_SEEDS = [219101, 219102, 219103, 219104];
 const RUNS_PER_SEED = 8;
 const MAX_TOTAL_DURATION_MS = 60_000;
 
-const differentialTest = swiftToolchainAvailable() ? test : test.skip;
+if (!swiftToolchainAvailable()) {
+  throw new Error('iOS snapshot differential requires the macOS Swift toolchain');
+}
 
-differentialTest('authored Swift and TypeScript golden cases agree', () => {
+test('authored Swift and TypeScript golden cases agree', { timeout: SWIFT_RUN_TIMEOUT_MS }, () => {
   const fixture = readIosSnapshotEngineFixture();
   const cases = fixture.cases
     .filter((testCase) => testCase.swift && !testCase.interactiveOnly)
@@ -36,41 +38,44 @@ differentialTest('authored Swift and TypeScript golden cases agree', () => {
   assert.equal(mismatch, undefined, mismatch ? JSON.stringify(mismatch, null, 2) : '');
 });
 
-differentialTest('raw unscoped depth compares the same acquisition frontier', () => {
-  const fixture = readIosSnapshotEngineFixture();
-  const depthCase = fixture.cases.find(
-    (testCase) => testCase.name === 'raw unscoped depth uses the acquisition frontier',
-  );
-  assert.ok(depthCase);
-  const deepNode = depthCase.nodes.at(-1);
-  assert.ok(deepNode);
-  const mismatch = compareDifferentialCases([
-    {
-      name: 'raw-depth-frontier-with-malformed-tail',
-      projection: 'raw',
-      interactiveOnly: false,
-      depth: 1,
-      scope: null,
-      foldPolicy: 'cursor-projected',
-      viewport: fixture.viewport,
-      nodes: [...depthCase.nodes, { ...deepNode, index: 1, parentIndex: 1, depth: 2 }],
-    },
-  ]);
-  assert.equal(mismatch, undefined, mismatch ? JSON.stringify(mismatch, null, 2) : '');
-});
+test(
+  'raw unscoped depth compares the same acquisition frontier',
+  { timeout: SWIFT_RUN_TIMEOUT_MS },
+  () => {
+    const fixture = readIosSnapshotEngineFixture();
+    const depthCase = fixture.cases.find(
+      (testCase) => testCase.name === 'raw unscoped depth uses the acquisition frontier',
+    );
+    assert.ok(depthCase);
+    const deepNode = depthCase.nodes.at(-1);
+    assert.ok(deepNode);
+    const mismatch = compareDifferentialCases([
+      {
+        name: 'raw-depth-frontier-with-malformed-tail',
+        projection: 'raw',
+        interactiveOnly: false,
+        depth: 1,
+        scope: null,
+        foldPolicy: 'cursor-projected',
+        viewport: fixture.viewport,
+        nodes: [...depthCase.nodes, { ...deepNode, index: 1, parentIndex: 1, depth: 2 }],
+      },
+    ]);
+    assert.equal(mismatch, undefined, mismatch ? JSON.stringify(mismatch, null, 2) : '');
+  },
+);
 
-differentialTest('deterministic Swift/TypeScript differential fuzz stays under 60000ms', () => {
-  assertDifferentialFuzz();
-});
-
-function assertDifferentialFuzz(): void {
-  const startedAt = performance.now();
-  for (const seed of FUZZ_SEEDS) {
-    assertDifferentialSeed(seed);
-    assertWithinKillCriterion(startedAt, seed);
-  }
-  assert.ok(true);
-}
+test(
+  'deterministic Swift/TypeScript differential fuzz stays under 60000ms',
+  { timeout: SWIFT_RUN_TIMEOUT_MS * FUZZ_SEEDS.length },
+  () => {
+    const startedAt = performance.now();
+    for (const seed of FUZZ_SEEDS) {
+      assertDifferentialSeed(seed);
+      assertWithinKillCriterion(startedAt, seed);
+    }
+  },
+);
 
 function assertDifferentialSeed(seed: number): void {
   const result = fc.check(