fix(web): show a preview-failed state when an image won't load

[Zach Dunn (zachdunn)]

In plain terms

A corrupt or unreachable image on the public file page used to show the browser’s broken-image icon. That looks like a dead page even when the file record is fine. The stage now swaps to a preview-failed state, and a render crash in the signed-in React islands no longer blanks the rest of the shell.

What it does / what it is not

• Does: if an image or video fails to load, hide the native chrome and show “Preview failed” with a short reason and an Open original link. Fit / Full width hide because they don’t apply.
• Does: use the same fallback shell for known non-previewable kinds (file / unsupported / missing) on the file page, gallery item, and gallery grid.
• Does: wrap the files table and screenshots islands so a render throw keeps the header, nav, and rail up.
• Does: serve the branded /500 page if the Worker itself throws, instead of a Cloudflare 1101.
• Does not: diagnose why the bytes failed (corrupt upload vs CDN vs decode). The copy stays generic on purpose.
• Does not: change 404 / unlisted / deleted file pages. Those already had their own states.

How to try it

The 25-byte cache probe from the original report is still live:

https://uploads.sh/f/default/gh/_cachetest/probe-1783465136.png

Locally, pnpm dev:web and open the same path on http://localhost:4321 — the page talks to the production API, so the broken file is the same one.

Technical notes

• Load failures are a client error (or complete && naturalWidth === 0) on <img> / <video>. The file record can be fine while the object 404s, fails to decode, or never arrives.
• Shared helpers live in media-load.ts; the visible shell is MediaFallback.astro. ImagePreview and MediaStage bind directly. The gallery grid uses data-media-load + bindMediaFallbacks.
• The two signed-in React mounts (WorkspaceFileTable, ScreenshotsByPath) wrap in IslandErrorBoundary. Other account/admin pages are vanilla JS and already have per-flow error copy.
• Thumbnail cells use <img onError> instead of a silent empty background-image.

Test plan

• pnpm --filter @uploads/web test (619 passing)
• Opened the original 25-byte probe in a local browser: stage shows Preview failed, Fit/Full width gone, rail still works
• Mobile viewport of the same page
• Missing file (/f/default/does-not-exist.png) still shows file.not_found
• /500 still renders the branded application-error card
• CI lint + typecheck + test on this PR

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[cloudflare-workers-and-pages]

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	uploads-auth	ee6cdce	Commit Preview URL Branch Preview URL	Aug 14 2026, 06:45 PM

[cloudflare-workers-and-pages]

Deploying with    Cloudflare Workers

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	uploads-web	ee6cdce	Commit Preview URL Branch Preview URL	Aug 14 2026, 06:46 PM

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_{/f/default/gh/_cachetest/probe-1783465136.png · error}

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