feat(attachments): play every browser-playable video container inline + label sniffed types

[lopugit]

Why

A QuickTime-container screen recording named .mp4 (magic bytes ftypqt) uploaded to a post rendered as a generic 41.7 MiB · application/octet-stream file card instead of a video player, because the inline allowlist only admitted magic-byte-verified video/mp4 + video/webm and everything else collapsed to an unlabeled octet-stream download.

What

1. Every browser-playable video container now renders inline. ATTACHMENT_INLINE_CONTENT_TYPES (server) and the mirrored INLINE_VIDEO_TYPES (client) grow from MP4/WebM to: QuickTime (video/quicktime), M4V (video/x-m4v), Ogg (video/ogg), 3GPP/3GPP2, and Matroska (video/x-matroska). The decision still comes exclusively from server-side magic-byte sniffing at upload finalization (file-type over the first 8 KiB) — never the filename extension — and SVG/HTML/active formats remain opaque downloads. SAFE_VIDEO_CONTENT_TYPES in attachmentCore matches so canonical crystal re-derivation agrees.

2. Opaque downloads now name their real container. New optional crystal field detectedContentType preserves the sniffed MIME whenever the served contentType stays application/octet-stream (AVI, WMV, MPEG-TS, HEIC, PDF, ZIP…). The canonical crystal closed union accepts the field only alongside an octet-stream contentType, so it is display metadata that can never widen inline serving or accompany an inline type. It flows through attachmentPublicProjection → post/comment projections → the client normalizer, and the download row shows a friendly label (AVI video, PDF document, raw MIME as fallback) instead of application/octet-stream. Legacy 4-key crystals stay canonical.

3. Graceful codec fallback. Container support ≠ codec support (HEVC QuickTime on Firefox, MKV on Safari). PostAttachments now degrades a failed <video> element to its named download row via the element error event instead of leaving an inert black player.

Registration / docs

• apiDocs.ts: upload-complete + content endpoint details and steps updated (docs registry is the route registration; no new endpoints).
• schemas/registry.ts: attachment schema documents the optional detectedContentType field; the pinned projection in builtinSchemaProjection.test.ts updated per its review-prompt comment.
• TESTING.md: three new manual checklist rows (QuickTime/MKV inline, sniffed-container labels, codec-failure fallback).

Tests & verification

• npm run test:unit — green (exit 0), including 110 attachment tests with new cases: every new container finalizes inline; AVI finalizes octet + detectedContentType; canonical-crystal accepts the 5-key shape and rejects detected-on-inline, detected=octet, uppercase, and non-string forgeries; UI mediaKind/normalizer/label coverage.
• Targeted ESLint on all changed files — clean.
• Full production build (npm run build in remix/: Vite client + Nitro Vercel output + verify) — passes.
• The reporter's actual file (ftypqt QuickTime bytes, 41.7 MB) was verified locally as the exact trigger: file-type reports video/quicktime, previously excluded by the allowlist.
• Local env has no private-storage S3 config, so the end-to-end upload was not exercised locally; preview-deployment verification notes to follow on this PR.

Out of scope (follow-up)

Existing ready attachments keep their stored octet-stream crystal (finalized before this change); a backfill that re-sniffs stored objects and upgrades crystals (e.g., the reporter's original post) needs S3 access inside the admin-migration frame and is left as a follow-up. Re-uploading the file after deploy gets the new behavior. Inline audio remains deliberately disabled pending a vetted player.

🤖 Generated with Claude Code

[vercel]

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Project	Deployment	Actions	Updated (UTC)
thingtime	Ready	Preview	Aug 19, 2026 3:01am
thingtime (develop)	Ready	Preview	Aug 19, 2026 3:01am

[github-actions]

🧹 Develop S3 preview removed

The PR-specific alias and every workflow-created develop deployment were removed when this PR closed.

The ordinary generated Vercel Preview remains available on the shared development runtime.

[github-actions]

🤝 Merged develop into claude/screenshot-video-display-e3a72d — conflicts auto-resolved by the resolve-pr-conflicts workflow.

Conflicted files:

• remix/app/docs/apiDocs.ts

Please review the merge commit before relying on it.

[lopugit]

Preview verification notes

Reporter's actual file, exact server decision path (real bytes, real file-type, real detectedAttachmentType):

file-type (first 8 KiB): {"ext":"mov","mime":"video/quicktime"}   ← ftypqt QuickTime container named .mp4
finalized crystal patch: {"contentType":"video/quicktime","mediaKind":"video"}   ← now renders inline

Before this PR the same bytes collapsed to application/octet-stream / file card, which is exactly the reported bug.

Preview deployment E2E (thingtime-48ftqdhxb-…vercel.app, commit b657f57):

• App boots, anonymous feed renders; register + session + upload-start API flow works.
• The branch preview uses an empty branch-scoped DB. Fresh-signup upload starts correctly return 403 public_uploads_not_approved / private_uploads_not_approved (PR fix(auth): withhold public uploads from new signups until admin approval (hotfix → main) #301/feat(auth): upload approval scopes — public / private / all variations #309 gating working as designed), and with no admin in that DB nobody can approve — so a full upload-to-playback pass on the preview needs an admin-approved account (owner action), or lands naturally after merge. Three inert throwaway users (tt-e2e-mov-*) exist only in that disposable branch DB.
• The develop merge commit (12c0c2a, AI-resolved) composes cleanly with the attachment-reorder changes: test:attachments (110) and test:schemas (53) green on the merged head.

Remaining manual check for an approved account (30 seconds): upload a macOS screen recording (or this PR's reporter file) to a post — it should finalize as video/quicktime and play inline; an AVI should show a download row labelled AVI video instead of application/octet-stream.

🤖 Generated with Claude Code