test(ui): poll compare-dock pointer hit after reveal transition

PR_POLICY_BODY.md

@@ -1,33 +1,29 @@
 ## Summary
 
-- On phone viewports (`max-width: 639px`), the header Mode picker opens as the shared bottom `Sheet` so the full mode list is scrollable with backdrop dismiss, Escape, focus trap, and return-focus to the Mode button.
-- Desktop (`sm:`+) keeps the existing anchored absolute dropdown, keyboard navigation, blur-leave dismiss, and outside-click dismiss via `useDismissableLayer`.
-- Hardens shared `Sheet` backdrop dismiss (gesture must start on the dimmed area; no click-through) and Tab-trap handling for roving `tabindex="-1"` menus.
-- Keeps PDF extractor process-tree termination reliable under suite load; Python binary resolution uses shared `python-bin` from main.
-- Fixes phone hydration: Mode layout gate initializes SSR-safe and syncs from `matchMedia` after mount / on open (avoids React #418 on phone route coverage).
+Hosted Production UI occasionally failed the differentials compare-dock tap assertion after scroll-reveal: a single `elementFromPoint` sample could miss while `translateY` was still easing. Poll the pointer-hit check through the reveal transition so the assertion waits for a stable hit target.
 
-## Verification
+The original phone Answer header gutter asymmetry is already fixed on `main` by #940 (`--header-edge-pad`); this PR does not change header spacing.
 
-- [x] Focused Vitest — header/sheet/audit-navigation contracts green after hydration fix
-- [x] Mode Playwright proofs — phone sheet open/scroll/select, backdrop dismiss + focus restore, desktop outside-click (no sheet), keyboard nav (5/5)
-- [x] Previously failing Production UI route-coverage journeys — DSM/specifier/differential phone hydration (3/3)
-- [x] `npm run check:production-readiness:ci` — READY (no blocking failures)
-- UI verification not run: full `verify:ui` / `verify:release` not required beyond the focused Mode + route-coverage proofs above
-- Provider-backed live evals not run: no answer-generation or retrieval scoring changes
+## Verification
 
-## Risk and rollout
+- [x] `npm run verify:pr-local`
+- [x] `npm run verify:ui` when UI, routing, styling, browser behavior, reduced-motion, or forced-colors behavior changed
+- [ ] `npm run verify:release` before release or handoff confidence claims
 
-- Risk: low — phone-only Mode open path plus shared Sheet dismiss/focus hardening; desktop Mode contracts preserved. Extractor change is fail-closed process cleanup only.
-- Rollback: revert this PR; Mode menu returns to the previous floating phone panel and prior Sheet/extractor behaviour.
-- Provider or production effects: None
+UI verification: Chromium compare-dock test and prior full `verify:ui` on this branch lineage; hosted Production UI also passed after the poll harden on earlier heads.
 
-## Clinical Governance Preflight
+- [ ] **`npm run eval:retrieval:quality` (must stay 36/36) when retrieval, ranking, selection, chunking, or scoring behavior changed** — not applicable
+- [ ] `npm run eval:rag -- --limit 15` + `npm run eval:quality -- --rag-only` when answer generation, the synthesis prompt, or answer post-processing changed — not applicable
+- [ ] `npm run check:production-readiness` when clinical workflow, privacy, environment, Supabase, source governance, or deployment behavior changed — not applicable
+- [ ] `npm run check:deployment-readiness` when deployment startup, hosting, or rollout behavior changed — not applicable
 
-Touched extractors/document.ts (fail-closed process-tree cleanup only). No answer, citation, source-governance, privacy, or document-access behaviour change.
+## Risk and rollout
 
-<!-- GOVERNANCE_PREFLIGHT -->
+- Risk: Low. Test-only wait hardening for a mid-transition pointer sample; no product behavior change.
+- Rollback: Revert the compare-dock `expect.poll` change in `tests/ui-tools.spec.ts`.
+- Provider or production effects: None
 
 ## Notes
 
-- Phone gate reuses `phoneSearchLayoutMediaQuery` (`max-width: 639px`).
-- `id="app-mode-menu"` is preserved inside the sheet for existing restore-focus guards.
+- Supersedes the component-level `px-3 sm:px-0` approach previously explored on this branch; #940 is the canonical phone header inset fix.
+- Also replaces the leftover Mode-menu `PR_POLICY_BODY.md` from #935 on this head so Sync applies this PR's description.

tests/ui-tools.spec.ts

@@ -1689,12 +1689,17 @@ test.describe("Clinical KB tools launcher", () => {
     await scrollPrimarySurface(page, 60);
     await expect(dock).not.toHaveAttribute("data-scroll-hidden", "true");
     await expect(compareAction).toBeVisible();
-    const restoredPointer = await compareAction.evaluate((element) => {
-      const rect = element.getBoundingClientRect();
-      const hit = document.elementFromPoint(rect.left + rect.width / 2, rect.top + rect.height / 2);
-      return hit === element || element.contains(hit);
-    });
-    expect(restoredPointer).toBe(true);
+    // Poll through the reveal transition: a single elementFromPoint sample can
+    // miss while translateY is still easing back into the viewport on CI.
+    await expect
+      .poll(async () =>
+        compareAction.evaluate((element) => {
+          const rect = element.getBoundingClientRect();
+          const hit = document.elementFromPoint(rect.left + rect.width / 2, rect.top + rect.height / 2);
+          return hit === element || element.contains(hit);
+        }),
+      )
+      .toBe(true);
     await expectNoPageHorizontalOverflow(page);
 
     // The result cards and compare bar remain in their non-desktop layout up