test(analytics): repair the PostHog contract tests

ROADMAP.md

@@ -3,24 +3,23 @@
 Loose, personal roadmap for the CodesWhat homepage. Not a ticket tracker (that's
 work). Just the ideas worth not forgetting.
 
-## Where things stand (2026-10-25)
+## Where things stand (2026-10-25, evening)
 
 The Catalogue redesign, the `/support` page and the analytics events shipped on
-2026-10-22 (#69, #70, #71). Production is `main@68520ee`. Two things are in
-flight:
-
-- [ ] Dependency security patch (Next 16.4.3, dompurify, sharp): PR #72 is green
-      on CI and preview and waiting on a delivered review before it lands in `dev`,
-      then a promotion to `main`.
-- [ ] CI hardening (support tests in `verify`, no duplicate promotion runs,
-      fork-safe skip, no persisted checkout credential, actions pinned to
-      commits): finished and tested locally, queued behind #72.
-- [ ] Remove the stray `visual-schedule-manager-portfolio/` app and root
-      `start.sh`; nothing references either.
+2026-10-22 (#69, #70, #71). On 2026-10-25 the dependency security patch (#72:
+Next 16.4.3, dompurify 3.4.17, sharp 0.35.5, which cleared every open Dependabot
+alert) and the CI hardening batch (#73: support tests in `verify`, no duplicate
+promotion runs, fork-safe skip, no persisted checkout credential, actions pinned
+to commits, stray `visual-schedule-manager-portfolio/` and `start.sh` removed)
+were promoted together in #74. Production is `main@722af11`, checked in a
+browser after the deploy.
+
+Still open:
+
 - [ ] Clean up `test/posthog.test.ts`, which imports a posthog-js internal path,
       then bump `posthog-js` and add `test:posthog:browser` to CI.
-- [ ] Close #58 (`.claude/` is already ignored on `main`). #57 is partly done;
-      the remaining items are tracked privately.
+- [ ] #57 is partly done (pins, credentials, CSP and input tests); the remaining
+      items are tracked privately.
 
 ## Progressive-enhancement fallback for the 3D layer
 

frontend/README-VERCEL.md

@@ -13,6 +13,12 @@ and persists after reload, the specimen plates render, and `/support` shows its
 buy links. Build success and analytics events alone do not establish that client
 initialization worked.
 
+Then run the PostHog response contract against the canonical domain:
+
+```sh
+POSTHOG_BROWSER_BASE_URL=https://codeswhat.com npm run test:posthog:browser
+```
+
 `npm run og` regenerates the share cards in `public/og*` with playwright-core
 and the locally installed Google Chrome; it isn't part of the build.
 

frontend/test/posthog-browser.test.mjs

@@ -14,6 +14,26 @@ test("production browser response keeps PostHog on the exact proxy", {
   assert.match(csp, /script-src[^;]*https:\/\/e\.codeswhat\.com/);
   assert.match(csp, /connect-src[^;]*https:\/\/e\.codeswhat\.com/);
   assert.doesNotMatch(csp, /\*\.posthog\.com|https:\/\/(app|us)\.posthog\.com/);
-  assert.doesNotMatch(body, /query-secret=should-not-leave/);
+  assert.match(
+    response.headers.get("cache-control") ?? "",
+    /\b(private|no-store)\b/,
+    "HTML reflects request data (Next.js flight payload), which is only safe if the page isn't shared-cached",
+  );
+  // Next.js inlines router state, including the request's own query, in
+  // self.__next_f.push(...) scripts. Only scripts whose body starts with that
+  // call are excluded; everything else must not reflect the query.
+  const flightCall =
+    /^\(self\.__next_f\s*=\s*self\.__next_f\s*\|\|\s*\[\]\)\.push\(|^self\.__next_f\.push\(/;
+  let flightScripts = 0;
+  const withoutFlightData = body.replace(/<script\b[^>]*>([\s\S]*?)<\/script>/g, (block, inner) => {
+    if (!flightCall.test(inner.trim())) return block;
+    flightScripts += 1;
+    return "";
+  });
+  assert.ok(
+    flightScripts > 0,
+    "expected Next.js Flight scripts in the HTML; the reflection exclusion is only valid when they exist",
+  );
+  assert.doesNotMatch(withoutFlightData, /query-secret/);
   assert.match(body, /<script\b[^>]*\bid="theme-init"/);
 });

frontend/test/posthog.test.ts

@@ -59,12 +59,20 @@ import {
 } from "../lib/posthog-privacy.ts";
 
 const require = createRequire(import.meta.url);
-const { PostHog } = require("../node_modules/posthog-js/lib/src/posthog-core.js") as {
+// Deep import on purpose: the published main bundle minifies `_runBeforeSend`
+// away, while lib/* is a published file in posthog-js's package.json `files`
+// with no exports map.
+const { PostHog } = require("posthog-js/lib/src/posthog-core.js") as {
   PostHog: new () => {
     config: { before_send?: (input: unknown) => unknown };
     _runBeforeSend: (input: unknown) => unknown;
   };
 };
+assert.equal(
+  typeof new PostHog()._runBeforeSend,
+  "function",
+  "posthog-js/lib/src/posthog-core.js no longer exposes PostHog#_runBeforeSend; the before_send pipeline contracts below need updating for this posthog-js version",
+);
 
 // posthog-js attaches these to every envelope by default (PostHog/posthog-js
 // packages/browser-common/src/utils/event-utils.ts, getEventProperties()).