feat(mothership): Chat-scoped outputs/ folder in VFS + Fork/Duplicate Chat

[j15z]

Summary

Adds two related capabilities on the chat/VFS surface, plus the field fixes found while testing them. (1) A chat-scoped outputs/ namespace for one-off generated files (images, audio, video, ffmpeg results) — separate from workspace files/, living with the chat, saveable to the workspace on request; agent-side steering is behind the mothership chat-scoped-outputs flag, so it dark-launches. (2) Fork and Duplicate — one engine, two gestures. The Fork button on each assistant reply copies the conversation up to and including that message into a fresh chat (Fork | <name>); the right-click Duplicate action is the same fork route with no cut point (upToMessageId is now optional) — a whole-chat copy titled <name> (Copy) that keeps every message and copies agent outputs too. In both modes, copied files get fresh row ids and storage keys, bytes are physically copied and quota-charged, and every in-transcript file reference is re-pointed at the copies so the copy survives deletion of the original. Duplicates ask the mothership fork endpoint for its whole-chat clone mode (compacted working memory preserved verbatim); branch forks keep the truncate-and-rebuild path. Schema: one additive migration (0254) adds nullable workspace_files.message_id, the provenance column that lets a branch fork copy only the uploads born at-or-before the cut.

Field fixes included (found via live testing of the above):

• Ghost resources: a branch fork copied the chat's resources jsonb wholesale, keeping chips for files it doesn't have; file resources whose chat-owned file wasn't copied are now dropped.
• Fork on a live message: a just-streamed reply carries a synthetic live-assistant:<streamId> id and forking it 400'd; the Fork button now waits for the persisted id.
• Media-tool reference inputs: generate_image/video/audio and ffmpeg resolved inputs.files workspace-only, so uploads//outputs/ references never loaded — and generate_image silently generated from the prompt alone. New shared resolveToolInputFile covers all three VFS namespaces, and unresolvable explicit references now fail the call instead of being silently skipped.
• Phantom-stream reconnect wedge: an outputs/ link click on the home surface minted an empty-id resource that 400'd the next send and wedged the UI in "running" for ~3 minutes; empty-id resources are now rejected and a failed POST rolls back instead of retry-reconnecting.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation
• Other: ___________

Testing

• Targeted suites green (vitest run from apps/sim): fork route, fork-chat-files, rewrite-file-references, effective-transcript, resolve-input-file, upload/output-file-reader, vfs, materialize-file, track-chat-upload → 10 files, 101 tests passing. New coverage: whole-chat duplicate (all messages kept, both file contexts copied, (Copy) title, Go body without upToMessageId, quota over upload+output bytes, empty-chat duplicate, empty-string id still 400s), ghost-resource regressions (uncopied output resource dropped; ghosts dropped even when zero files copy; duplicates keep and re-point everything), and chat-scoped resolver cases.
• tsc --noEmit ✅ 0 errors · biome check ✅ clean · check:api-validation ✅ · check:react-query ✅. (apps/docs type-check noise is pre-existing — missing generated .source artifact; this branch touches no docs files.)
• Manual (local dev, three rounds of field-testing): uploads copy with their bytes and re-pointed references; branch forks start with clean outputs/; duplicates open as <name> (Copy) with every message; reference-image generation actually uses the uploaded reference.
• Reviewers should focus on: the two-mode branch in fork/route.ts (isWholeChatDuplicate drives the message cut, file listing, title, Go body, and analytics); the ghost-resource drop rule in rewriteResourceFileRefs (chat-owned ∧ not-copied ⇒ dropped; shared workspace files pass through); the deliberate quota divergence from the workspace-fork precedent (forked bytes ARE counted — see the comment at the increment site); and migration 0254 (additive, no backfill, NULL = birth-unknown ⇒ included in every fork).

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

Screenshots/Videos

Companion PR

Companion (mothership): https://github.com/simstudioai/mothership/pull/342

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Project	Deployment	Actions	Updated (UTC)
docs	Ready	Preview, Comment	Jul 4, 2026 12:05am

[cursor]

PR Summary

High Risk
Changes span file authorization (privacy leak fix), fork transactions with blob copies and quota, and broad chat/stream client state — mistakes could leak outputs across members or leave broken forks/resources.

Overview
Introduces a chat-scoped outputs/ namespace for agent-generated one-offs (parallel to uploads/), wired through VFS read/glob/grep, GET /api/mothership/chats/[chatId]/outputs, UI listing in the resource picker, and writeWorkspaceFileByPath / media tools when outputs/<name> is requested on interactive turns. materialize_file can promote outputs to workspace files/ with name disambiguation.

Fork / duplicate expands the mothership fork route: optional upToMessageId (branch vs whole-chat duplicate), physical file row + blob copies with quota checks, transcript/resource reference rewrites, ghost resource dropping, failed-copy cleanup, and sidebar Duplicate plus enabled message Fork (blocked on live assistant ids).

Security / access: output files require workspace membership and row owner; DB lookup includes output context so serve/view works; /api/files/view allows embedding output files.

Hardening: empty resource ids rejected in API and client; stream 404 stops reconnect loops; failed chat POST rolls back optimistic state; resolveToolInputFile for media reference paths; upload message_id stamping for timeline-aware fork cuts; chat cleanup includes output context.

^{Reviewed by Cursor Bugbot for commit 4e82a25. Bugbot is set up for automated code reviews on this repo. Configure here.}

[greptile-apps]

Greptile Summary

This PR adds two related features to the chat/VFS surface: (1) a chat-scoped outputs/ namespace for agent-generated files (images, audio, video, ffmpeg results) that live with the chat and can optionally be saved to the workspace, and (2) Fork and Duplicate — one engine that either branches a conversation at a message cutpoint or deep-copies the whole chat including outputs. It also bundles several field fixes found during live testing: ghost resources on branch forks, a live-message fork 400, media tool input resolution across all VFS namespaces, and the phantom-stream reconnect wedge.

• Schema change (0254): additive nullable workspace_files.message_id column that lets a branch fork copy only uploads born at-or-before the cut point; NULL rows are conservatively included in every fork.
• New storage context (output): uploadChatOutput writes agent-generated files to workspace_files with context='output', added to cleanup scopes and authorization paths with an ownership guard so workspace membership alone cannot serve another member's chat outputs.
• Two-mode fork route: isWholeChatDuplicate drives the message cut, file listing, title, Go body, and analytics; blob copies are best-effort post-transaction with dead-row cleanup on failure.

Confidence Score: 5/5

Safe to merge; the new output context authorization is backed by ownership checks and tests, the fork transaction is atomic with post-commit best-effort cleanup, and the schema change is purely additive.

The two-mode fork route is well-structured: quota gate before the transaction, atomic row plan inside it, and dead-row cleanup after blob failures. The output context ownership rule is applied on both the explicit-context serve path and the inferred-workspace path, covered by authorization tests. The message_id column is nullable and backward-compatible. The three flagged observations are an incomplete write-once mode guard, an advisory name dedup without a DB constraint, and a missing query invalidation — none affect data integrity or security.

resource-writer.ts (write-once guard covers only overwrite, not create-or-update) and workspace-file-manager.ts (advisory name dedup for outputs has no backing DB constraint).

Important Files Changed

Filename	Overview
apps/sim/app/api/mothership/chats/[chatId]/fork/route.ts	Two-mode fork/duplicate route; quota gate, transactional file row plan, post-commit best-effort blob copy with dead-row cleanup. Well-structured but outputs/ write-once enforcement is incomplete.
apps/sim/lib/copilot/chat/fork-chat-files.ts	New file: listForkableChatFiles/listDuplicableChatFiles/planChatFileCopies/executeChatFileBlobCopies implement per-chat file copying with idMap/keyMap for reference rewriting. Well-tested.
apps/sim/lib/copilot/chat/rewrite-file-references.ts	New file: rewrites message file refs and resource file refs using idMap/keyMap; drops ghost chat-owned resources not copied in a branch fork.
apps/sim/lib/copilot/tools/handlers/output-file-reader.ts	New file: read/list/grep for chat-scoped output files; mirrors upload-file-reader.ts with VFS name normalization and most-recent tie-breaking.
apps/sim/lib/copilot/vfs/resource-writer.ts	Adds outputs/ dispatch: rejects overwrite mode, calls uploadChatOutput for interactive chats, transparently redirects to files/ for non-interactive runs. create-or-update is not rejected.
apps/sim/app/api/files/authorization.ts	Routes output context to verifyWorkspaceFileAccess; adds outputOwnershipSatisfied check; WORKSPACE_FILE_LOOKUP_CONTEXTS extended to include output; backed by new tests.
apps/sim/lib/uploads/contexts/workspace/workspace-file-manager.ts	Adds uploadChatOutput (write-only, advisory name dedup), getPreviewableWorkspaceFile (output ownership guard), messageId param added to trackChatUpload.
apps/sim/app/workspace/[workspaceId]/home/hooks/use-chat.ts	Fixes phantom-stream reconnect wedge (streamStarted flag, StreamNotFoundError), empty-id resource guard, rollback on pre-stream POST failure.
apps/sim/lib/copilot/tools/server/image/generate-image.ts	Switches to resolveToolInputFile covering uploads/ and outputs/; unresolvable explicit references now fail the call rather than silently proceeding.
packages/db/schema.ts	Additive nullable message_id column on workspaceFiles; no FK by design; migration 0254 is a single ALTER TABLE ADD COLUMN with no backfill.
apps/sim/lib/cleanup/chat-cleanup.ts	Correctly extends CHAT_SCOPED_CONTEXTS to include output so agent-generated outputs are deleted with the owning chat.
apps/sim/lib/copilot/tools/server/files/resolve-input-file.ts	New unified resolver for tool input paths covering uploads/, outputs/, and workspace files/ namespaces.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant UI as UI (Sidebar/MessageActions)
    participant ForkAPI as POST /chats/[id]/fork
    participant DB as Database (Drizzle TX)
    participant Blob as Storage (S3/Local)
    participant GoAPI as Go Copilot Service

    UI->>ForkAPI: "{upToMessageId?} (omit = duplicate)"
    ForkAPI->>DB: load messages, list source files
    ForkAPI->>ForkAPI: quota gate (sum sizes)
    ForkAPI->>DB: BEGIN TX
    DB->>DB: INSERT copilot_chats (new row)
    DB->>DB: INSERT workspace_files (copy rows, fresh id+key)
    DB->>DB: rewriteResourceFileRefs (drop ghosts)
    DB->>DB: appendCopilotChatMessages (rewritten refs)
    DB->>DB: COMMIT
    ForkAPI->>Blob: executeChatFileBlobCopies (best-effort)
    alt blob copy fails
        ForkAPI->>DB: DELETE dead workspace_files rows
        ForkAPI->>DB: removeChatResources (broken chips)
    end
    ForkAPI->>GoAPI: POST /api/chats/fork (clone service state)
    ForkAPI-->>UI: "{id, failedFileCopies?}"
    UI->>UI: "navigate to new chat, show warning if failedFileCopies > 0"

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%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
sequenceDiagram
    participant UI as UI (Sidebar/MessageActions)
    participant ForkAPI as POST /chats/[id]/fork
    participant DB as Database (Drizzle TX)
    participant Blob as Storage (S3/Local)
    participant GoAPI as Go Copilot Service

    UI->>ForkAPI: "{upToMessageId?} (omit = duplicate)"
    ForkAPI->>DB: load messages, list source files
    ForkAPI->>ForkAPI: quota gate (sum sizes)
    ForkAPI->>DB: BEGIN TX
    DB->>DB: INSERT copilot_chats (new row)
    DB->>DB: INSERT workspace_files (copy rows, fresh id+key)
    DB->>DB: rewriteResourceFileRefs (drop ghosts)
    DB->>DB: appendCopilotChatMessages (rewritten refs)
    DB->>DB: COMMIT
    ForkAPI->>Blob: executeChatFileBlobCopies (best-effort)
    alt blob copy fails
        ForkAPI->>DB: DELETE dead workspace_files rows
        ForkAPI->>DB: removeChatResources (broken chips)
    end
    ForkAPI->>GoAPI: POST /api/chats/fork (clone service state)
    ForkAPI-->>UI: "{id, failedFileCopies?}"
    UI->>UI: "navigate to new chat, show warning if failedFileCopies > 0"

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