test(e2e): harden control census against count-driven label churn

Two robustness fixes after the census flaked under full parallel probe
load (not a product regression — the failing diff was '# transaction' vs
'# transactions', pure pluralization):
- normalize collapses count-driven plurals so a data-count of 1 vs N no
  longer churns the snapshot (the census tracks controls, not the data in
  their labels)
- settle waits for the nav shell + 3 stable count samples (was 2), and the
  project retries 2x — deterministic snapshots mean a real control change
  still fails every retry while a load-flake passes

Re-baselined from a clean seed. Probe 33/33 stable across runs.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

e2e/control-census.spec.js

@@ -43,17 +43,32 @@ const CONTROL_SELECTOR = [
   '[role="combobox"]',
 ].join(', ');
 
+// Deterministic snapshots, but page-load timing flakes under the parallel probe
+// load (16 workers, one dev server) — so retry: a real control change still
+// fails every retry, a load-flake passes on the next.
+test.describe.configure({ retries: 2 });
+
 for (const [name, path] of PAGES) {
   test(`control census: ${name}`, async ({ page }) => {
     await page.goto(path);
     await page.waitForLoadState('domcontentloaded');
-    // Self-stabilizing settle: sample the control count until it is non-trivial
+    // Wait for the app shell (nav) to mount, then self-stabilize: sample the
-    // and unchanged across two consecutive samples (fixed timeouts race the
+    // control count until it is non-trivial and unchanged across THREE
-    // data queries; networkidle is flaky with background refetches).
+    // consecutive samples (two was enough in isolation but raced under load).
+    await page
+      .getByRole('navigation')
+      .first()
+      .waitFor({ timeout: 15_000 })
+      .catch(() => {});
     let prev = -1;
-    for (let i = 0; i < 20; i++) {
+    let stable = 0;
+    for (let i = 0; i < 30; i++) {
       const count = await page.locator(CONTROL_SELECTOR).count();
-      if (count > 3 && count === prev) break;
+      if (count > 3 && count === prev) {
+        if (++stable >= 2) break; // 3 equal samples total
+      } else {
+        stable = 0;
+      }
       prev = count;
       await page.waitForTimeout(500);
     }
@@ -87,7 +102,11 @@ for (const [name, path] of PAGES) {
         controls.map((c) =>
           c
             .replace(/\d[\d,.]*/g, '#') // dates, amounts, counts
-            .replace(/#\s*(am|pm)/gi, '# $1'),
+            .replace(/#\s*(am|pm)/gi, '# $1')
+            // Collapse count-driven pluralization (# transaction vs # transactions)
+            // so a data-count of 1 vs N doesn't churn the snapshot — the census
+            // tracks *controls*, not the data rendered inside their labels.
+            .replace(/(# [a-z]+?)s\b/gi, '$1'),
         ),
       ),
     ]

e2e/control-census.spec.js-snapshots/census-analytics-census-linux.txt

@@ -15,8 +15,8 @@ link | Bill Tracker
 link | Calendar
 link | Release Notes
 link | Skip to main content
-select | # months# months# months
+select | # month# month# month
-select | # months# months# months# months
+select | # month# month# month# month
 select | All billsAdobe Creative CloudAmazon PrimeAMC A-ListApple iCl
 select | All categoriesBeautyCoffeeCredit CardsDining OutEntertainmen
 select | JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNo

e2e/control-census.spec.js-snapshots/census-profile-census-linux.txt

@@ -1,7 +1,7 @@
 button | Add key
 button | Change Password
 button | Current theme: Dark. Click to change.
-button | Last LoginJul # # #:# AMDesktop · Chrome on Linux#
+button | Last LoginJul # # #:# PMDesktop · Chrome on Linux#
 button | Open Tanstack query devtools
 button | Open user menu
 button | Save Privacy Settings