feat(mobile): pick, share, and receive files in threads

[t3dotgg]

Mobile can attach photos today, but it cannot pick documents or retain files shared from other apps. This adds Photos and Files controls when the connected environment supports file uploads, plus native share targets for documents, audio, and video.

Files stay with drafts and queued messages until delivery. Uploads reuse verified pending references, rejected sends restore the draft, and cleanup waits until no draft, outbox message, or incoming share owns the file. Saved iOS attachments continue working when an app update moves the data container. Picker and open-in-place source documents are never deleted.

Received files download from the selected environment and open in the native save/share sheet with their filenames preserved. Leaving the thread cancels unfinished downloads. Files handed to another app remain cached long enough for the recipient to read them. Unknown attachment types remain visible as inert rows.

Validation: 210 focused mobile tests pass, along with mobile typechecking, targeted lint and formatting, and Expo native configuration introspection for iOS and Android.

The native share registration and Expo SDK 57 Android sharing patch require new iOS and Android builds. Device verification is still required for native sharing, file picking, and save/share behavior before shipping those builds. No simulator or device session was run for this update. The tolerant attachment contract from #8235 must ship to older mobile clients before they receive threads containing files.

Original work by Theo Browne with Claude Fable 5 in the Claude Code harness. Prior modernization by GPT-5.6 Sol in the Codex harness. This update by nathree in the Codex harness.

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Note

Medium Risk
Touches share ingestion, local file lifecycle, and server pending-upload paths with many edge cases (Android content URIs, iOS container moves); mistakes could leak files or block sends, but ownership checks and rollback paths mitigate the worst outcomes.

Overview
Extends the mobile composer and thread experience from image-only attachments to generic files, gated on each server’s file-upload capabilities and size limits.

Attach and send: Drafts now use a DraftComposerAttachment union. The composer can pick documents via pickComposerFiles / persistComposerAttachmentFile (app-owned copies, enforced counts and byte limits), upload file bytes through new prepareTurnAttachments (reuse pending uploads, persist ids on drafts/outbox), and show non-image thumbnails in ComposerAttachmentStrip. New-task and thread composers offer Photos vs Files when the server supports files.

Share into the app: Native share registration accepts files on iOS/Android. Incoming shares ingest file/audio/video payloads without base64, persist copies, filter attachments by destination server config, and roll back persisted files if durable inbox writes fail. Temporary share cleanup only deletes URIs under app-owned roots so open-in-place shares cannot wipe the sender’s document.

Read in threads: The feed renders file attachments as tappable rows that resolve a signed URL and download + share via downloadAndShareAttachment; unknown attachment types render inert rows.

Supporting changes include stricter incoming-share storage loading (strict mode), unused attachment cleanup sweeps on import/cancel/send, and moving some outbox removal imports to thread-outbox-removal.

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Note

Add file picking, sharing, and receiving to mobile threads

• Broadens DraftComposerAttachment from image-only to a union of image and file types across composer drafts, outbox models, and incoming share drafts.
• Refactors outbox drain to upload attachments before sending and adds per-message revision tracking in thread-outbox-manager.ts for compare-and-set updates, removals, and clears to protect against concurrent edits.
• Adds pickComposerFiles for selecting files, downloadAndShareAttachment for downloading and sharing received files, and renders file attachments with icons in the composer strip and thread feed.
• Updates incoming share processing to accept non-image files with size validation against server capabilities, persist them locally, and roll back on failure.
• Patches expo-sharing on Android to support simultaneous text and file payloads and preserve original filenames from DISPLAY_NAME.
• Risk: removeThreadOutboxMessage and clearThreadOutboxEnvironment exports are removed from thread-outbox.ts and moved to thread-outbox-removal.ts; out-of-tree callers importing from the old module will break.

^{Macroscope summarized 85b91ca.}

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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	13.3 KiB	13.3 KiB	+2 B (+0.0%)	15.1 KiB	✅
Codex	Thread snapshot wire	6.9 KiB	6.9 KiB	−3 B (−0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.4 KiB	6.4 KiB	+5 B (+0.1%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	55.6 KiB	55.6 KiB	0 B (0.0%)	66.4 KiB	✅
Codex	Live turn messages	11	11	0 (0.0%)	21	✅
Claude	Total thread wire	13.4 KiB	13.4 KiB	+3 B (+0.0%)	15.1 KiB	✅
Claude	Thread snapshot wire	6.9 KiB	6.9 KiB	+1 B (+0.0%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.5 KiB	6.5 KiB	+2 B (+0.0%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	56.4 KiB	56.4 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	11	11	0 (0.0%)	21	✅

Baseline: 7880a6e · PR result: 85b91ca · 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]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR adds a substantial mobile file workflow across native sharing, local persistence, uploads, queued delivery, and received-file sharing. It also changes native product defaults and requires new iOS/Android builds, so the scope and runtime impact warrant human review.

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[cursor]

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

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[t3dotgg]

@juliusmarminge you down to push this one over the finish line?