feat(web): upload image attachments before sending

[t3dotgg]

Image attachments currently travel inside turn-start WebSocket messages as large base64 strings. The earlier direct-upload proposal would also break released mobile apps and older remote servers.

Images now upload over signed HTTP URLs as soon as they are attached. Existing mobile clients keep their current inline attachment format, and newer web clients fall back to inline uploads when an older server does not support direct uploads. Existing drafts and stashed prompts are preserved.

Based on #6276.

Verified with focused contract, server, web, mobile, and client-runtime tests, all 129 server router tests, the production web build, and targeted type checks.

Built by GPT-5.6 Sol in the Codex harness.

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Note

High Risk
Adds a signed-token HTTP upload path and filesystem persistence for pending attachments, plus claim/copy logic during turn dispatch. Token validation, size checks, and pending-only deletes are security-sensitive.

Overview
Composer images now upload immediately over signed HTTP URLs instead of riding as base64 in the turn-start WebSocket payload. Newer web clients wait for uploads (with progress, retry, and send blocking) and send attachment ids; older servers and mobile clients keep the inline dataUrl path via an optional attachmentUploads capability.

The server issues HMAC-signed upload URLs, accepts POST bytes at /api/attachments/upload/*, stores them as pending-* files, and claims them on dispatch by copying to a new thread-scoped id so failed bootstraps can retry. Stale pending (24h) and .part (1h) files are swept on startup and periodically; delete RPCs only remove pending uploads.

Thread ids that sanitize to pending are remapped to _pending so they cannot collide with the reserved pending segment.

^{Reviewed by Cursor Bugbot for commit 2718e15. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Upload image attachments before sending messages via signed URLs

• Adds server-side attachment upload flow: signed URL issuance via WS RPC, token-validated HTTP POST endpoint at /api/attachments/upload, atomic .part-based file storage, and stale upload sweeping (1h for partials, 24h for pending) at startup and URL issuance
• Introduces client upload queue in attachmentUploadQueue.ts with per-environment concurrency limit of 3, progress reporting, retry/cancel/release lifecycle, and send-gating until all images reach ready or failed state
• Extends Normalizer.normalizeDispatchCommand to claim pending uploads into thread-owned final paths with size/type validation, rollback of claimed copies on failure, and cleanup of claimed attachments on dispatch errors
• Updates ChatComposer and ChatView to start uploads on image add, display per-image progress and retry UI, use uploaded attachment metadata instead of inline data URLs, and release uploads after successful turn start
• Risk: toSafeThreadAttachmentSegment now maps sanitized thread IDs equal to pending to _pending; any existing thread whose ID sanitizes to pending will have its attachment directory path change. ClientThreadTurnStartCommand schema now accepts a union of UploadChatAttachment and ChatAttachment for message attachments.

^{Macroscope summarized 2718e15.}

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[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.4 KiB	13.4 KiB	−6 B (−0.0%)	15.1 KiB	✅
Codex	Thread snapshot wire	6.9 KiB	6.9 KiB	+2 B (+0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.5 KiB	6.5 KiB	−8 B (−0.1%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	55.0 KiB	55.0 KiB	0 B (0.0%)	66.4 KiB	✅
Codex	Live turn messages	16	16	0 (0.0%)	21	✅
Claude	Total thread wire	13.4 KiB	13.4 KiB	+4 B (+0.0%)	15.1 KiB	✅
Claude	Thread snapshot wire	6.9 KiB	6.9 KiB	−7 B (−0.1%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.6 KiB	6.6 KiB	+11 B (+0.2%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	55.8 KiB	55.8 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	16	16	0 (0.0%)	21	✅

Baseline: b4be33f · PR result: 2718e15 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 109.4 KiB
• Claude decoded thread snapshot: 110.1 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

[macroscopeapp]

UI consistency review: one finding on the new upload-progress overlay in the composer attachment thumbnails.

^{Posted via Macroscope — UI Consistency}

[macroscopeapp]

Two new retry actions convey the upload failure reason through the native title attribute instead of the shared Tooltip primitive. The repo enforces t3code/no-native-title-tooltip ("Use Tooltip + TooltipTrigger + TooltipPopup from components/ui/tooltip") — the rule only skips these because it ignores capitalized components, and Button forwards title straight onto the native <button>. Since upload.reason is the only place the specific failure ("Unsupported image type", "Upload rejected (500)", "Not connected") is surfaced, a native tooltip makes it unreachable on touch and keyboard focus, and it looks unlike the adjacent Tooltip in the same composer block.

^{Posted via Macroscope — UI Consistency}

[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 1 potential issue.

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[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR introduces a full signed image-upload workflow with new HTTP and WebSocket APIs, authorization changes, filesystem persistence, cleanup, and client-side upload state management. Its broad cross-layer runtime impact and security-sensitive upload path warrant human review.

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