Bust Astro build cache when the markdown pipeline changes

[benbalter]

Root cause

The failing E2E test — link-validation.spec.ts:92 › sample blog posts should not have broken internal links — has failed on every main push since the /q/<id> quote pages were retired. It flags two dead links in the cathedral-bazaar-management post: /q/match-management-to-the-moment/ and /q/cathedral-bazaar-operating-systems/.

The source is correct — those posts use inline :quote[…]{#id} directives that render #quote- anchors, and a cold build produces zero /q/ links. This is CI cache staleness, not content:

• Both workflows cache node_modules/.astro (Astro's content layer) with restore-keys: astro-cache-<os>-.
• Astro caches rendered markdown keyed on each file's content digest and reuses it for unchanged files regardless of the remark/rehype plugin code.
• When the quote plugin switched from /q/ links to #quote- anchors, the cathedral post's .md never changed — so CI restored the pre-change cache and kept shipping its stale /q/ HTML. astro preview (what E2E runs against) doesn't honor the /q/* → /posts/ 301 in _redirects, so it 404s.

Reproduced the reuse mechanism locally (building with a different plugin than what's cached leaves unchanged content un-re-rendered) and confirmed via the .astro data-store cache.

Fix

Fold a pipeline fingerprint (src/lib/**, astro.config.mjs, src/content.config.ts, package-lock.json) into both the cache key and the restore-keys prefix, in astro-e2e.yml and build-and-deploy.yml. A rendering-pipeline change now busts the cache; content-only edits still reuse it.

The deploy workflow had the identical bug, so prod was serving the degraded /q/ → /posts/ 301 on every quote share link until an unrelated edit touched those posts — this fixes that path too.

Verification

• Cold build (rm -rf node_modules/.astro && npm run build): 0 /q/ links, 27 quote posts rendering #quote- anchors.
• All 5 link-validation tests green against a stable preview server, including the originally-failing one.
• Both workflow YAMLs parse clean.

The new key format can't prefix-match any existing cache, so the first run on each workflow cold-builds automatically; no manual cache purge needed.

🤖 Generated with Claude Code