🐛 Fixed post card assets going missing until restart (in-memory serving)

[sagzy]

ref https://linear.app/ghost/issue/ONC-1865

Note: This is one of two alternative fixes for the same incident, opened for comparative review. The other is the minimal disk-recovery approach: #29129. Both supersede #29056, whose review surfaced races in the recovery-on-ENOENT design (torn reads from non-atomic writes, response-cache poisoning, throttle 404ing concurrent requests, rebuild loops for never-produced files).

Problem

/public/cards.min.css and /public/cards.min.js are minified at runtime into content/public/ and served by reading them back from disk. If the built files go missing at runtime, or the content folder is unwritable (EACCES), every request 404s until the process restarts — ~486 production sites accumulated in this state during Jun 25–29.

Solution: serve card assets from memory

The disk round-trip buys nothing: the assets are rebuilt from theme sources on every boot anyway, and the serving middleware already held the response body in memory permanently. The disk copy was never a real cache — it was just the failure surface.

• CardAssets.load() now builds in memory (Minifier.minifyInMemory()) and stores the outputs on the service; getContent(filename) is the source of truth for serving. A successful build is always servable — ENOENT/EACCES on the destination can no longer take the assets offline. The disk write still happens as best-effort back-compat, with failures logged and ignored.
• The two card routes use a new createInMemoryAssetMiddleware() that serves straight from the service with the same header shape as before (md5 ETag, Content-Length, Cache-Control), memoized per build.
• Build policy now lives in one place, AssetsMinificationBase.ensureLoaded(): concurrent callers join a single in-flight build; a 10s retry backoff stops a persistently failing build from minifying per request; invalidate() (theme activation) no longer forgets an in-flight build — a generation counter re-runs load() with the new config instead of allowing two concurrent minifier runs.
• serveMiddleware() no longer lets a rejected load() escape as an unhandled rejection (which left requests hanging under Express 4) — this also fixes the hang for AdminAuthAssets.

Testing

• New unit tests for ensureLoaded() (join-in-flight, backoff + expiry, invalidate resets backoff, mid-build invalidate re-runs load with no concurrency), CardAssets in-memory outputs (getContent, hasFile, ready + servable even when the disk write EACCESes), and the in-memory middleware (headers/ETag, {{blog-url}} replacement, 404 when the build legitimately produces no file, build trigger when not ready).
• ghost/core unit suite: 7187 passed; the 3 failures are pre-existing on main (verified by baseline run).

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Ensure the fix-ci command is configured to always run in your CI pipeline to get automatic fixes in future runs. For more information, please see https://nx.dev/ci/features/self-healing-ci

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Command	Status	Duration	Result
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☁️ Nx Cloud last updated this comment at 2026-07-06 09:49:10 UTC