feat(01-14): monitorTypeSurfaces:'include' — narrow picker to monitor surfaces only

[per Plan 01-14; closes B-01-14-01 via Step 1b lockstep]

- src/offscreen/recorder.ts: add monitorTypeSurfaces:'include' as top-level
  DisplayMediaStreamOptions sibling of video: (W3C Screen Capture spec §6.1;
  Chrome >= 119; removes tab/window panes from the operator's picker per
  Plan 01-10 RESEARCH §5 + §Pitfall-5 recommendation). Typed widening cast
  extended in lockstep to keep the explicit-typing contract (no `as any`).
  D-15 post-grant validation block at recorder.ts:294 UNCHANGED — belt
  (picker narrowing) + suspenders (post-grant tear-down) chain preserved.

- tests/offscreen/display-surface-constraint.test.ts: lockstep update of
  the strict-deep-equality assertion at lines 223-226 with the same key
  ordering as the source change (video -> monitorTypeSurfaces -> audio).
  toHaveBeenCalledWith contract preserved (NO expect.objectContaining —
  the test author's "catches future drops of ANY field" discipline is
  honored). This edit + the source change land in the SAME commit so the
  98/98 baseline never crosses a commit boundary in RED state.

- src/test-hooks/offscreen-hooks.ts: capture last constraints object in
  module-scoped `lastGetDisplayMediaConstraints` cell (was `_constraints`
  received-but-unused; renamed to `constraints`); add `get-last-getDisplayMedia-constraints`
  bridge op to the __mokoshOffscreenQuery dispatcher between
  get-display-surface and get-segment-count. Defensive try/catch mirrors
  the existing dispatcher pattern; the cell is module-internal so the
  MokoshTestSurface cross-cast in types.ts requires NO change (decision
  documented inline in offscreen-hooks.ts).

- tests/uat/extension-page-harness.ts: add `assertA23` mirroring `assertA3`
  (bridge query → 2-check AssertionResult: non-null constraints + value).
  Extend the `Window.__mokoshHarness` declaration + runtime export + status
  bar text + console.log to reference A23.

- tests/uat/lib/harness-page-driver.ts: export `driveA23(page)` mirroring
  the `driveA14` page.evaluate wrapper shape. Standard read-only driver.

- tests/uat/harness.test.ts: extend FORBIDDEN_HOOK_STRINGS (line 85) with
  `lastGetDisplayMediaConstraints` and `get-last-getDisplayMedia-constraints`.
  Import driveA23. Append `{ name: 'A23', drive: driveA23 }` to the drivers
  array after the A14 entry. Update header comment + orchestrator stdout
  to reflect A14 + A23 chain. The `Total = drivers.length + 1` arithmetic
  adapts automatically: 14 + 1 = 15 → 15 + 1 = 16.

- tests/background/no-test-hooks-in-prod-bundle.test.ts: lockstep
  extension of FORBIDDEN_HOOK_STRINGS (line 105) with the same 2 strings.
  Header comment updated to "Total: 12 surface strings." (was 10).
  Confirms production `dist/` has ZERO occurrences after `npm run build`
  via the `__MOKOSH_UAT__` dead-branch tree-shake (T-01-14-04 mitigation).

D-01 (whole-desktop only via getDisplayMedia; reject window/tab surfaces) is
the design intent that monitorTypeSurfaces:'include' realizes at the picker-
UI level. D-15 post-grant validation (recorder.ts:294-307) remains the
actual enforcement against managed-policy/DevTools/older-Chrome overrides.

Verification chain (per Plan 01-14 §verify; clean post-commit):
- `npx tsc --noEmit` exit 0
- `npm run build` exit 0; dist/ produced, monitorTypeSurfaces ships in
  the offscreen chunk as the operator-facing picker hint
- `npm run build:test` exit 0; dist-test/ produced with the harness
  hooks intact (gated)
- `npm test` 100/100 GREEN (was 98/98; +2 via the 2 new FORBIDDEN_HOOK_STRINGS
  parametrized tests — both PASS, production bundle hook-free)
- `npm run test:uat` 16/16 GREEN (15 → 16 via A23). A23 reads constraints
  `{video: {...}, monitorTypeSurfaces: 'include', audio: false}` from the
  fakeGetDisplayMedia capture cell — round-trips through the full call site.
- Production bundle spot-check:
    `grep -rc 'lastGetDisplayMediaConstraints\|get-last-getDisplayMedia-constraints' dist/ | grep -v ':0$'`
    → empty (all `:0` filtered) → ZERO leakage.

References:
- W3C Screen Capture §6.1 DisplayMediaStreamOptions:
  https://www.w3.org/TR/screen-capture/#dom-displaymediastreamoptions-monitortypesurfaces
- Chrome screen-sharing-controls (Chrome 119+):
  https://developer.chrome.com/docs/web-platform/screen-sharing-controls
- Plan 01-10 RESEARCH §5 + §Pitfall-5 (recommendation provenance):
  .planning/phases/01-stabilize-video-pipeline/01-10-RESEARCH.md
- Architectural-note (replaces retired AMENDMENT-A.md improvisation per
  01-11-SUMMARY): canonical GSD ceremony — plan → checker (B-01-14-01)
  → executor → SUMMARY (this commit).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/offscreen/recorder.ts

@@ -267,11 +267,27 @@ async function startRecording(): Promise<void> {
     // Use a typed widening through `DisplayMediaStreamOptions &
     // {video: Record<...>}` instead of `as any` to stay explicit
     // about the precise field we're adding.
+    //
+    // Plan 01-14: `monitorTypeSurfaces: 'include'` is a TOP-LEVEL member
+    // of DisplayMediaStreamOptions (W3C Screen Capture spec §6.1 — NOT
+    // nested in `video:`; that would route it to MediaTrackConstraints).
+    // Chrome ≥ 119 (Chrome screen-sharing-controls release notes:
+    // https://developer.chrome.com/docs/web-platform/screen-sharing-controls)
+    // honors the constraint by narrowing the picker dialog to ONLY
+    // monitor surfaces — the Window and Chrome-Tab panes are elided.
+    // The post-grant validation block immediately below remains the
+    // actual enforcement (constraints are HINT-class per spec — the
+    // operator can still override via the picker UI on older Chrome
+    // versions, and managed-policy / DevTools can override anywhere).
+    // Belt (picker-UI narrowing) + suspenders (post-grant tear-down)
+    // per Plan 01-10 RESEARCH §5 + §Pitfall-5 recommendation.
     const stream = await navigator.mediaDevices.getDisplayMedia({
       video: { displaySurface: 'monitor', cursor: 'always' },
+      monitorTypeSurfaces: 'include',    // Plan 01-14 — Chrome ≥ 119 picker narrowing per W3C spec §6.1
       audio: false,    // SPEC §9 — Phase 2 / CAP-01 territory
     } as DisplayMediaStreamOptions & {
       video: { displaySurface: 'monitor'; cursor: 'always' };
+      monitorTypeSurfaces: 'include';
     });
     mediaStream = stream;
     // Plan 01-11 Task 2: wire the live MediaStream into the test hook

src/test-hooks/offscreen-hooks.ts

@@ -99,6 +99,22 @@ let fakeCanvas: HTMLCanvasElement | null = null;
 let fakeAnimationHandle: number | null = null;
 let fakeDrawInterval: ReturnType<typeof setInterval> | null = null;
 
+/**
+ * Plan 01-14 A23 contract — record the last-received constraints object
+ * from every `fakeGetDisplayMedia` invocation. The `installFakeDisplayMedia`
+ * shim already accepts the `constraints` parameter (previously prefixed
+ * `_constraints` as received-but-unused — see below), so the production
+ * call site's `monitorTypeSurfaces: 'include'` sibling lands here. The
+ * `get-last-getDisplayMedia-constraints` bridge op (later in this file)
+ * reads it for harness inspection.
+ *
+ * `null` until any `getDisplayMedia` call has been made — A23 always
+ * runs AFTER A2's `setupFreshRecording` so the cell is populated by
+ * then. Test bundle only; gated identically to the rest of this module
+ * by the top-of-module `__MOKOSH_UAT__` import in src/offscreen/recorder.ts.
+ */
+let lastGetDisplayMediaConstraints: DisplayMediaStreamOptions | null = null;
+
 /**
  * Replace `navigator.mediaDevices.getDisplayMedia` with a synthetic
  * implementation backed by a hidden 30 fps canvas. The returned
@@ -233,8 +249,13 @@ export function installFakeDisplayMedia(): void {
   // straight assignment would trip the type checker. The runtime
   // dispatch ignores arguments entirely — fake stream regardless.
   const fakeGetDisplayMedia = async (
-    _constraints?: DisplayMediaStreamOptions,
+    constraints?: DisplayMediaStreamOptions,
   ): Promise<MediaStream> => {
+    // Plan 01-14 A23: capture the production call's constraints object
+    // so the harness can verify `monitorTypeSurfaces: 'include'` reached
+    // the call site. Default to null on undefined-args so the bridge op
+    // reports an unambiguous "no args" signal rather than `undefined`.
+    lastGetDisplayMediaConstraints = constraints ?? null;
     return mintStream();
   };
   (navigator.mediaDevices as unknown as {
@@ -355,6 +376,14 @@ globalThis.__mokoshTest = {
 //       zero count is meaningful. The 10s rotation cadence (D-13;
 //       SEGMENT_DURATION_MS) means a recording that has been live for
 //       ~35s should report count ≥ 3 (3 × 10s = 30s = MAX_SEGMENTS).
+//   op='get-last-getDisplayMedia-constraints' → { constraints: object|null }
+//     — Plan 01-14 A23 contract. Returns the most-recent constraints
+//       object captured by `fakeGetDisplayMedia`. Used by the harness to
+//       verify the production call site passes `monitorTypeSurfaces: 'include'`
+//       (W3C Screen Capture spec §6.1; Chrome ≥ 119 picker-narrowing
+//       semantics). `null` only when no getDisplayMedia call has happened
+//       yet — A23 always runs AFTER A2's setupFreshRecording so a non-null
+//       value is the expected case.
 // Unknown ops respond { ok: false, error: 'unknown-op' }.
 //
 // The bridge handler MUST run BEFORE the production offscreen bridge
@@ -433,6 +462,34 @@ chrome.runtime.onMessage.addListener((rawMessage, _sender, sendResponse) => {
     }
     return false;
   }
+  if (op === 'get-last-getDisplayMedia-constraints') {
+    // Plan 01-14 A23 contract — return the most-recent constraints object
+    // captured by the `fakeGetDisplayMedia` shim. Production code at
+    // src/offscreen/recorder.ts:270 calls `navigator.mediaDevices.getDisplayMedia({
+    // video: {...}, monitorTypeSurfaces: 'include', audio: false })`; this op
+    // exposes that object so the harness can assert
+    // `constraints.monitorTypeSurfaces === 'include'`.
+    //
+    // `null` is returned in two cases:
+    //   (a) No `getDisplayMedia` call has been made yet — A23 always runs
+    //       AFTER A2's setupFreshRecording so this is unreachable in the
+    //       orchestrated sequence;
+    //   (b) The call was made with `undefined` args — also unreachable for
+    //       the production call site which always supplies the constraints
+    //       object.
+    // try/catch is defensive — bridge handlers must never propagate
+    // exceptions to chrome.runtime.sendMessage (the dispatcher contract
+    // shared by all ops above).
+    try {
+      sendResponse({ constraints: lastGetDisplayMediaConstraints });
+    } catch (err) {
+      sendResponse({
+        ok: false,
+        error: err instanceof Error ? err.message : String(err),
+      });
+    }
+    return false;
+  }
   if (op === 'get-segment-count') {
     // Plan 01-13 Wave 3D A11 contract — return the offscreen recorder's
     // live segment count via the `segmentCountGetter` closure wired at

tests/background/no-test-hooks-in-prod-bundle.test.ts

@@ -60,13 +60,16 @@
 //   - `__mokoshOffscreenQuery`      — 01-13 page→offscreen bridge message type
 //   - `get-display-surface`         — 01-13 Wave 3A bridge op string (A3 contract)
 //   - `get-segment-count`           — 01-13 Wave 3D bridge op string (A11 contract)
+//   - `lastGetDisplayMediaConstraints` — 01-14 A23 offscreen-side cell name
+//   - `get-last-getDisplayMedia-constraints` — 01-14 A23 bridge op string
 //
-// Total: 10 surface strings. Each MUST be absent from EVERY file under
+// Total: 12 surface strings. Each MUST be absent from EVERY file under
 // `dist/` post-build. The list is mirrored by the harness's A0
-// assertion (tests/uat/harness.test.ts in Wave 3A) so the same
+// assertion (tests/uat/harness.test.ts in Wave 3A; Plan 01-14 lockstep
-// invariant is enforced at unit-test time (fast, every CI run) AND
+// extension) so the same invariant is enforced at unit-test time
-// at UAT-harness time (belt+suspenders per the orchestrator-loaded
+// (fast, every CI run) AND at UAT-harness time (belt+suspenders per
-// `feedback-pre-checkpoint-bundle-gates.md` memory).
+// the orchestrator-loaded `feedback-pre-checkpoint-bundle-gates.md`
+// memory).
 //
 // Implementation mirrors `sw-bundle-import.test.ts`'s execFile pattern:
 //   - Spawn `npm run build` via execFile so the build is reproducible
@@ -113,6 +116,13 @@ const FORBIDDEN_HOOK_STRINGS: ReadonlyArray<string> = [
   '__mokoshOffscreenQuery',
   'get-display-surface',
   'get-segment-count',
+  // Plan 01-14 A23 surface — lockstep with UAT A0 inventory at
+  // tests/uat/harness.test.ts:85. Verifies the `__MOKOSH_UAT__` Vite
+  // define-token dead-branch tree-shake correctly elides the new
+  // `lastGetDisplayMediaConstraints` cell + the `get-last-getDisplayMedia-constraints`
+  // bridge op from production `dist/` (T-01-14-04 mitigation).
+  'lastGetDisplayMediaConstraints',
+  'get-last-getDisplayMedia-constraints',
 ];
 
 /** How long the build child has to finish (`npm run build` is ~10s).

tests/offscreen/display-surface-constraint.test.ts

@@ -219,9 +219,13 @@ describe('Plan 01-09 D-15-display-surface: getDisplayMedia constraints + post-gr
 
     expect(getDisplayMediaSpy).toHaveBeenCalledTimes(1);
     // Strict deep-equality — NOT expect.objectContaining. Catches a
-    // future drop of either `displaySurface` or `cursor`.
+    // future drop of either `displaySurface` or `cursor` (D-15) OR
+    // the Plan 01-14 top-level `monitorTypeSurfaces: 'include'` picker-
+    // narrowing constraint. Key ordering matches the source call at
+    // src/offscreen/recorder.ts: video → monitorTypeSurfaces → audio.
     expect(getDisplayMediaSpy).toHaveBeenCalledWith({
       video: { displaySurface: 'monitor', cursor: 'always' },
+      monitorTypeSurfaces: 'include',
       audio: false,
     });
   });

tests/uat/extension-page-harness.ts

@@ -1903,6 +1903,81 @@ async function assertA14(): Promise<AssertionResult> {
   return result;
 }
 
+/**
+ * A23 — Plan 01-14 picker-narrowing constraint verification.
+ *
+ * Asserts that the production `getDisplayMedia` call at
+ * src/offscreen/recorder.ts:270 passes `monitorTypeSurfaces: 'include'`
+ * as a top-level constraint sibling of `video:` (W3C Screen Capture
+ * spec §6.1; Chrome ≥ 119 picker-narrowing semantics — only monitor
+ * surfaces are offered, no Window/Chrome-Tab panes).
+ *
+ * Queries the offscreen bridge `get-last-getDisplayMedia-constraints` op
+ * which reads the recorded constraints from the `fakeGetDisplayMedia`
+ * shim's last invocation. A23 chains AFTER A14 (A14 is the final read-
+ * only post-SAVE state check; A23 is independent because A2's
+ * setupFreshRecording already invoked getDisplayMedia and the recorded
+ * cell is read-only from A23's perspective — no side effects).
+ *
+ * Mirrors `assertA3` (line 686): bridge query → structured AssertionResult
+ * with two checks (non-null constraints + monitorTypeSurfaces value).
+ *
+ * @returns Structured result with the monitorTypeSurfaces check.
+ */
+async function assertA23(): Promise<AssertionResult> {
+  const result: AssertionResult = {
+    passed: false,
+    name: 'A23 — getDisplayMedia called with monitorTypeSurfaces:\'include\' (Plan 01-14 picker narrowing)',
+    checks: [],
+    diagnostics: [],
+  };
+
+  try {
+    diag(result, "Step 1: bridge query 'get-last-getDisplayMedia-constraints'");
+    const resp = await offscreenQuery<{
+      constraints?: DisplayMediaStreamOptions | null;
+      ok?: boolean;
+      error?: string;
+    }>('get-last-getDisplayMedia-constraints');
+    diag(result, `Step 1 result: ${JSON.stringify(resp)}`);
+
+    if (resp.ok === false) {
+      throw new Error(
+        `get-last-getDisplayMedia-constraints returned ok=false: ${resp.error ?? '(no error)'}`,
+      );
+    }
+    const constraints = resp.constraints ?? null;
+
+    result.checks.push({
+      name: 'A23.1: constraints object recorded by fakeGetDisplayMedia (non-null)',
+      expected: 'non-null DisplayMediaStreamOptions',
+      actual: constraints === null ? '<null>' : JSON.stringify(constraints),
+      passed: constraints !== null,
+    });
+    // The constraints object MAY be widened by the production cast (per
+    // Plan 01-14 source change) to include the top-level field, so we
+    // dot-access via the same indexed-property shape (`as any`) since
+    // monitorTypeSurfaces is not in the lib.dom.d.ts DisplayMediaStreamOptions
+    // ambient (TypeScript bundled types lag the W3C spec — same lag that
+    // forced the `cursor: 'always'` typed-widening cast on recorder.ts:268).
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any -- constraints widening for top-level monitorTypeSurfaces sibling per W3C spec §6.1 (lib.dom.d.ts lag)
+    const monitorTypeSurfaces = (constraints as any)?.monitorTypeSurfaces ?? null;
+    result.checks.push({
+      name: 'A23.2: constraints.monitorTypeSurfaces === \'include\' (W3C spec §6.1; Chrome ≥ 119 picker narrowing)',
+      expected: 'include',
+      actual: monitorTypeSurfaces,
+      passed: monitorTypeSurfaces === 'include',
+    });
+
+    result.passed = result.checks.every((c) => c.passed);
+  } catch (err) {
+    result.error = err instanceof Error ? err.message : String(err);
+    diag(result, `THREW: ${result.error}`);
+  }
+
+  return result;
+}
+
 /**
  * Read `chrome.runtime.getManifest().version`. Used by the host-side
  * orchestrator at startup to capture the expected version for A13's
@@ -1934,6 +2009,7 @@ declare global {
       assertA12: () => Promise<AssertionResult>;
       assertA13: () => Promise<AssertionResult>;
       assertA14: () => Promise<AssertionResult>;
+      assertA23: () => Promise<AssertionResult>;
       getManifestVersion: () => Promise<string>;
     };
   }
@@ -1954,14 +2030,15 @@ window.__mokoshHarness = {
   assertA12,
   assertA13,
   assertA14,
+  assertA23,
   getManifestVersion,
 };
 
 const statusEl = document.getElementById('status');
 if (statusEl !== null) {
-  statusEl.textContent = 'Harness ready. window.__mokoshHarness.{assertA1..assertA14, getManifestVersion} available.';
+  statusEl.textContent = 'Harness ready. window.__mokoshHarness.{assertA1..assertA14, assertA23, getManifestVersion} available.';
 }
 
-console.log('[harness-page] ready — window.__mokoshHarness installed (Plan 01-13 Task 9: A1..A14 + getManifestVersion)');
+console.log('[harness-page] ready — window.__mokoshHarness installed (Plan 01-13 Task 9: A1..A14 + Plan 01-14: A23 + getManifestVersion)');
 
 export {};

tests/uat/harness.test.ts

@@ -19,7 +19,17 @@
 // Plan 01-13 Task 9 closure (debug 01-09-save-stops-recording) adds A14:
 // post-SAVE auto-stop state check (badge='', popup='', no new
 // mokosh-recovery-*). Chains off A13's SAVE_ARCHIVE — read-only
-// observation, no new dispatch. Final target: 15/15 GREEN.
+// observation, no new dispatch.
+//
+// Plan 01-14 adds A23 as the final functional assertion (post-A14 chain):
+// read-only inspection of the last `getDisplayMedia` constraints from
+// A2's setupFreshRecording; verifies the production call site passes
+// `monitorTypeSurfaces: 'include'` (W3C Screen Capture spec §6.1; Chrome
+// ≥ 119 picker-narrowing semantics — removes the Window + Chrome-Tab
+// panes from the operator's picker dialog). A23 has no side effects
+// (the constraints cell is populated by A2 and read by the bridge op);
+// hence independent of A14's no-side-effects post-SAVE contract.
+// Final target: 16/16 GREEN.
 //
 // The orchestrator structure is final from Wave 3A onward; future waves
 // only fill in the assertion-driver stubs.
@@ -67,6 +77,7 @@ import {
   driveA12,
   driveA13,
   driveA14,
+  driveA23,
   getManifestVersion,
 } from './lib/harness-page-driver';
 import {
@@ -93,6 +104,10 @@ const FORBIDDEN_HOOK_STRINGS: ReadonlyArray<string> = [
   '__mokoshOffscreenQuery',
   'get-display-surface',
   'get-segment-count',
+  // Plan 01-14 A23 surface — lockstep with unit-gate inventory at
+  // tests/background/no-test-hooks-in-prod-bundle.test.ts:105.
+  'lastGetDisplayMediaConstraints',
+  'get-last-getDisplayMedia-constraints',
 ];
 
 /** Build timeout for the pre-flight production rebuild (matches unit-gate value). */
@@ -230,8 +245,8 @@ async function assertA0_GrepGate(): Promise<{
  * @returns Process exit code: 0 on 15/15 GREEN, 1 on any failure.
  */
 async function main(): Promise<number> {
-  process.stdout.write('\nMokosh Plan 01-13 — UAT harness orchestrator\n');
+  process.stdout.write('\nMokosh Plan 01-13 + 01-14 — UAT harness orchestrator\n');
-  process.stdout.write('Architecture: A0 pre-flight + extension-internal page driver (A1..A13)\n');
+  process.stdout.write('Architecture: A0 pre-flight + extension-internal page driver (A1..A14, A23)\n');
   process.stdout.write('='.repeat(72) + '\n');
 
   // A0 pre-flight (no Chrome launch needed; runs against built dist/).
@@ -309,6 +324,13 @@ async function main(): Promise<number> {
     // notification ids state; no new SAVE dispatch — A13's already
     // exercised the SAVE path. Recording stays stopped after A14.
     { name: 'A14', drive: driveA14 },
+    // Plan 01-14 A23: read-only inspection of the last getDisplayMedia
+    // constraints object captured by A2's setupFreshRecording. Verifies
+    // the production call at src/offscreen/recorder.ts:270 passes
+    // `monitorTypeSurfaces: 'include'` (W3C Screen Capture spec §6.1;
+    // Chrome ≥ 119 picker-narrowing semantics). Independent of A14 —
+    // no new getDisplayMedia call, no new state change.
+    { name: 'A23', drive: driveA23 },
   ];
 
   const buffers = { swConsole: handles.swConsole, offConsole: handles.offConsole };
@@ -351,7 +373,9 @@ async function main(): Promise<number> {
   }
 
   const passedCount = results.filter((r) => r.passed).length;
-  // Total = 1 (A0) + drivers.length (A1..A14) = 15.
+  // Total = 1 (A0) + drivers.length (A1..A14, A23) = 16. Plan 01-14
+  // appended A23 after A14 — the running count adapts via `drivers.length`
+  // so no manual update is needed when future plans extend the chain.
   const total = drivers.length + 1;
   const finalPassed = passedCount + 1; // +1 for A0 (we already passed it to reach here)
 

tests/uat/lib/harness-page-driver.ts

@@ -993,6 +993,33 @@ export async function driveA14(page: Page): Promise<AssertionRecord> {
   }) as AssertionRecord;
 }
 
+/* ─── Plan 01-14 — driveA23 (monitorTypeSurfaces picker-narrowing) ─── */
+
+/**
+ * Drive A23 (Plan 01-14 picker-narrowing constraint verification).
+ * Standard page.evaluate wrapper — page side bridges to the offscreen
+ * `get-last-getDisplayMedia-constraints` op and asserts that the
+ * production `getDisplayMedia` call passes `monitorTypeSurfaces: 'include'`
+ * at the top level (W3C Screen Capture spec §6.1; Chrome ≥ 119 picker-
+ * narrowing semantics — only monitor surfaces are offered, no Window/
+ * Chrome-Tab panes).
+ *
+ * Chains AFTER driveA14 in the orchestrator. Read-only operation — A23
+ * does NOT call getDisplayMedia again; it reads the constraints recorded
+ * by A2's setupFreshRecording.
+ *
+ * @param page - The harness page from `launchHarnessBrowser`.
+ * @returns Structured AssertionRecord with 2 checks (A23.1 non-null + A23.2 monitorTypeSurfaces value).
+ */
+export async function driveA23(page: Page): Promise<AssertionRecord> {
+  return await page.evaluate(async () => {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any -- evaluate runs in browser context where Window types are loose.
+    const harness = (window as any).__mokoshHarness;
+    const r: AssertionRecord = await harness.assertA23();
+    return r;
+  }) as AssertionRecord;
+}
+
 // Note (Wave 3D): the AssertionWithBytes interface is retained at the
 // top of this file as a public export — but Wave 3D's drivers no
 // longer use it (the host side now does all bytes-handling internally