feat(seo): strengthen interview hub internal linking

.githooks/pre-commit

@@ -33,7 +33,7 @@ fi
 STAGED_FILES="$(mktemp)"
 trap 'rm -f "$STAGED_FILES"' EXIT
 
-git diff --cached --name-only --diff-filter=ACMR > "$STAGED_FILES"
+git diff --cached --name-only --diff-filter=ACMRD > "$STAGED_FILES"
 
 if [ ! -s "$STAGED_FILES" ]; then
   echo "[pre-commit] No staged files. Skipping checks."

.github/workflows/angular-upgrade-visual.yml

@@ -18,6 +18,8 @@ jobs:
         browser: [chromium, firefox, webkit]
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
+        with:
+          fetch-depth: 0
       - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e
         with:
           node-version-file: .nvmrc
@@ -59,11 +61,17 @@ jobs:
       PLAYWRIGHT_WEB_SERVER: '1'
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
+        with:
+          fetch-depth: 0
       - name: Checkout immutable Angular 17 reference
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
         with:
           ref: 68d4939b049e266c1f68efc6b0cf0b94a8854274
           path: angular17-reference
+      - name: Apply the intentional interview hub navigation to the reference
+        run: |
+          git -C angular17-reference apply --check ../frontend/e2e/reference-patches/interview-hub-navigation.patch
+          git -C angular17-reference apply ../frontend/e2e/reference-patches/interview-hub-navigation.patch
       - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e
         with:
           node-version: 20.19.6
@@ -73,7 +81,7 @@ jobs:
           cp frontend/e2e/upgrade-visual.spec.ts frontend/e2e/interview-mocks.ts angular17-reference/frontend/e2e/
           cd angular17-reference/frontend
           npx playwright install --with-deps chromium
-      - name: Capture reference using the original application
+      - name: Capture Angular 17 reference with the same intended navigation
         working-directory: angular17-reference/frontend
         env:
           PLAYWRIGHT_PORT: '4251'

.github/workflows/fullstack-smoke.yml

@@ -45,6 +45,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
+        with:
+          fetch-depth: 0
 
       - name: Setup Node
         uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e

.github/workflows/lemonsqueezy-test-checkout.yml

@@ -31,6 +31,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
+        with:
+          fetch-depth: 0
 
       - name: Reject production target
         run: |

.github/workflows/playwright.yml

@@ -29,6 +29,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
+        with:
+          fetch-depth: 0
 
       - name: Setup Node
         uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e
@@ -93,6 +95,11 @@ jobs:
         env:
           CI: true
 
+      - name: Run production incident content and interaction contracts
+        run: npm run test:e2e:incidents:prod
+        env:
+          CI: true
+
       - name: Upload Playwright artifacts (on failure)
         if: failure()
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a
@@ -119,6 +126,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
+        with:
+          fetch-depth: 0
 
       - name: Setup Node
         uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e
@@ -179,6 +188,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
+        with:
+          fetch-depth: 0
 
       - name: Setup Node
         uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e
@@ -259,6 +270,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
+        with:
+          fetch-depth: 0
 
       - name: Setup Node
         uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e

.github/workflows/seo-guard.yml

@@ -7,14 +7,17 @@ jobs:
   prerender-sitemap-guard:
     name: SEO Prerender Guard
     runs-on: ubuntu-latest
-    timeout-minutes: 10
+    # PR merge commits can require a full semantic-history backfill before prerendering.
+    timeout-minutes: 20
     defaults:
       run:
         working-directory: frontend
 
     steps:
       - name: Checkout
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
+        with:
+          fetch-depth: 0
 
       - name: Setup Node
         uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e

cdn/data-version.json

@@ -1,3 +1,3 @@
 {
-  "dataVersion": "df2deae26a65"
+  "dataVersion": "b6eeb5c8fd50"
 }

docs/references/angular21-upgrade-verification.md

@@ -19,6 +19,15 @@ scenarios and Playwright version as the candidate, then compares the candidate
 without `--update-snapshots`. The two runs share the same runner and font setup.
 Do not update candidate snapshots to hide migration differences.
 
+The interview-hub navigation introduced by `6becd398115e8f25e674e06e87527f371ad457f9`
+is an intentional product change after the migration. CI applies the reviewed
+`frontend/e2e/reference-patches/interview-hub-navigation.patch` to the pinned
+Angular 17 source before capturing its reference. The patch contains only the
+header navigation changes and their responsive spacing; it preserves the
+reference's Angular 17 component metadata, imports, dependencies and remaining
+application. Screenshot thresholds and candidate-update restrictions remain
+unchanged. Future product changes require separate review of any reference patch.
+
 ## Angular 17 baseline
 
 - Production build and 615 prerender routes: passed.

frontend/.gitignore

@@ -30,6 +30,8 @@ yarn-error.log
 
 # Miscellaneous
 /.angular/cache
+/.angular/seo/
+/src/app/generated/seo-content-dates.ts
 /.angular/cdn-assets/
 .sass-cache/
 /connect.lock
@@ -43,6 +45,7 @@ testem.log
 /test-results/
 /e2e/*-snapshots/
 !/e2e/upgrade-visual.spec.ts-snapshots/
+!/e2e/incident-visual.spec.ts-snapshots/
 
 # System files
 .DS_Store

frontend/README.md

@@ -190,6 +190,24 @@ Or run locally with a prerendered build:
 2) Serve `dist/frontendatlas/browser` with a static server (any tool you prefer).
 3) `PLAYWRIGHT_BASE_URL=http://localhost:4200 PLAYWRIGHT_SSR=1 npx playwright test e2e/seo-ssr.spec.ts`
 
+### Incident content and UI contracts
+
+Build first with `npm run build:prod`, then run `npm run test:e2e:incidents:prod`.
+The suite checks every public incident's real prerendered educational markup,
+Premium solution exclusion, saved-session hydration, scoring, navigation, and
+keyboard accessibility. Backend requests are mocked. This suite also runs in
+the Playwright CI job against the production output.
+
+On macOS, `npm run test:e2e:incidents:visual` compares the same production output
+with 93 Chromium reference images captured before the renderer change
+(application revision `28a133614deb`). It covers every free incident at 390/1440px
+and the full Stale Search Race flow at 360/390/834/1366/1440px, with zero differing
+pixels allowed. The visual suite is opt-in (`INCIDENT_VISUAL=1`) and skips other
+operating systems because the committed references use macOS font rendering.
+Do not use `--update-snapshots` to verify a rendering change: investigate the
+diff first. New platform references must come from a known-good application
+using the same Chromium and font environment as the candidate.
+
 ## Draft versioning
 
 To safely handle “CDN updates a question (same id) while users have local drafts”, drafts are versioned by content. See `frontend/docs/draft-versioning.md`.
@@ -208,6 +226,63 @@ Notes:
 - Apply targeted rewrites only for private CSR paths (for this repo: `/dashboard`, `/profile`, `/admin/*`, `/billing/*`, `/onboarding/*`, premium `/tracks/:slug`, premium `/companies/:slug/*`).
 - Keep unknown URLs as real `404` responses.
 
+## Sitemap content dates
+
+`npm run gen:seo` generates sitemap XML under `.angular/seo/sitemaps/` and the
+ignored Angular module `src/app/generated/seo-content-dates.ts`. These artifacts
+are generated before builds and tests, and are not committed. Angular copies only
+the XML files to the public build; Git provenance remains in
+`.angular/seo/content-dates.json` on the build machine.
+The generated date module is excluded from `data-version` hashing, so assigning
+commit dates does not invalidate user drafts or require another content commit.
+
+Dates come from the last meaningful content transition in the target commit's
+first-parent Git history, using the committer's UTC day. A merge counts when its
+content enters that branch; a revert is also a content update. Build time, file
+mtime and editorial `updatedAt` fields do not determine SEO dates. Existing
+publication and editorial dates remain separate from `dateModified`.
+
+The inventory selects individual catalog objects, article content and explicitly
+mapped page dependencies. It ignores date fields, generated files, tests,
+comments and visual styles. Adding a public route requires a content mapping.
+When changing the meaning of a projection, increment `PROJECTION_VERSION` and
+rebuild the historical baseline from Git; do not stamp the current date. A build
+with an older projection checkpoint recomputes dates from full Git history
+without rewriting the checkpoint.
+
+- Generate: `npm run gen:seo` (also part of `gen:data`, install and test commands).
+- Verify existing output without writes: `npm run check:seo-dates`.
+- Validate staged sources without writes or staging: `node scripts/generate-seo-content-dates.mjs --staged`.
+- Rebuild the historical checkpoint: `node scripts/seo-content-history.mjs --baseline --target <existing-commit>`.
+- Regression tests: `npm run test:seo-dates`.
+
+The tracked `scripts/seo-content-baseline.json` is a historical checkpoint, not an
+always-current generated manifest. Review its source commits and date changes
+when deliberately refreshing it. The normal build resolves later transitions
+without changing this file. Unknown historical dates are omitted with a reason.
+
+Local uncommitted content is reported as pending and has no published lastmod.
+CI and Vercel builds reject pending semantic content. `--strict` enables that
+check explicitly for local generation. The pre-commit check validates the staged
+snapshot; it never treats unstaged files as staged or assigns a publication date
+before the commit exists.
+
+A Git checkout is required. CI checks out full history; `ensure-seo-history.mjs`
+completes a shallow checkout from its existing `origin` using existing credentials.
+For [Vercel's shallow checkout](https://vercel.com/kb/guide/how-do-i-use-the-ignored-build-step-field-on-vercel)
+without `origin`, it fetches the checked-out commit directly from GitHub using the
+validated `VERCEL_GIT_PROVIDER`, `VERCEL_GIT_REPO_OWNER` and `VERCEL_GIT_REPO_SLUG`
+[system metadata](https://vercel.com/docs/environment-variables/system-environment-variables).
+It does not add remotes or change credentials. Private repositories need an
+authenticated `origin` or a full Git checkout; inaccessible history still fails.
+`node scripts/ensure-seo-history.mjs --check` checks without fetching. Missing Git,
+unavailable history, invalid dates or missing content mappings fail explicitly;
+there is no build-time date fallback. Verify this prerequisite in a Vercel preview
+before releasing a change to the deployment pipeline.
+
+After building, `npm run seo:meta-check` verifies sitemap/JSON-LD date agreement,
+and `npm run seo:link-equity` verifies public URL reachability and inclusion.
+
 ## Further help
 
 To get more help on the Angular CLI use `ng help` or go check out the [Angular CLI Overview and Command Reference](https://angular.io/cli) page.

frontend/angular.json

@@ -32,7 +32,7 @@
               "src/llms.txt",
               {
                 "glob": "sitemap*.xml",
-                "input": "src",
+                "input": ".angular/seo/sitemaps",
                 "output": "/"
               },
               {
@@ -217,7 +217,7 @@
               "src/llms.txt",
               {
                 "glob": "sitemap*.xml",
-                "input": "src",
+                "input": ".angular/seo/sitemaps",
                 "output": "/"
               },
               {
@@ -337,7 +337,7 @@
               "src/robots.txt",
               {
                 "glob": "sitemap*.xml",
-                "input": "src",
+                "input": ".angular/seo/sitemaps",
                 "output": "/"
               },
               {

frontend/e2e/accessibility.smoke.spec.ts

@@ -109,6 +109,13 @@ test.describe('accessibility smoke', () => {
       name: 'Modal opens visually but fails screen-reader users',
     })).toBeVisible();
 
+    // The prerendered heading is visible before the simulator is interactive.
+    // Browser progress is written when the incident component has mounted.
+    await expect.poll(() => page.evaluate(() => {
+      const progress = JSON.parse(localStorage.getItem('fa:practice:progress:v3:guest') || '{}');
+      return progress['incident:modal-screen-reader-failure']?.started === true;
+    })).toBe(true);
+
     await page.getByRole('button', { name: 'Begin simulator' }).click();
 
     const group = page.getByRole('radiogroup', { name: 'What is actually broken here?' });

frontend/e2e/filtering.spec.ts

@@ -94,8 +94,13 @@ test('coding list filters sync to URL and persist on reload + back', async ({ pa
   await page.goto('/coding');
   await expect(page.getByTestId('coding-list-page')).toBeVisible();
   await expect(page.getByLabel('Search questions', { exact: true })).toBeVisible();
+  const technologyLinks = page.getByTestId('coding-tech-question-hubs').getByRole('link');
+  await expect(technologyLinks).toHaveCount(7);
 
   await page.getByTestId('filter-tech-javascript').click();
+  await expect(page).toHaveURL(/tech=javascript/);
+  await expect(technologyLinks).toHaveCount(1);
+  await expect(technologyLinks).toHaveAttribute('href', '/javascript/interview-questions');
   await page.getByTestId(`filter-difficulty-${jsFilters.difficulty}`).click();
   await page.getByTestId(`filter-importance-${jsFilters.importance}`).click();
   await page.getByTestId('coding-list-search').fill(JS_QUESTION.title);
@@ -109,6 +114,8 @@ test('coding list filters sync to URL and persist on reload + back', async ({ pa
 
   await page.reload();
   await expect(page.getByTestId('coding-list-page')).toBeVisible();
+  await expect(technologyLinks).toHaveCount(1);
+  await expect(technologyLinks).toHaveAttribute('href', '/javascript/interview-questions');
 
   await expect(page.getByTestId('coding-list-search')).toHaveValue(JS_QUESTION.title);
   await expect(page.getByTestId('filter-tech-javascript')).toHaveClass(/is-active/);
@@ -124,6 +131,8 @@ test('coding list filters sync to URL and persist on reload + back', async ({ pa
 
   await page.goBack();
   await expect(page.getByTestId('coding-list-page')).toBeVisible();
+  await expect(technologyLinks).toHaveCount(1);
+  await expect(technologyLinks).toHaveAttribute('href', '/javascript/interview-questions');
 
   await expect(page).toHaveURL(/tech=javascript/);
   await expect(page).toHaveURL(new RegExp(`diff=${jsFilters.difficulty}`));