TuneCamp Collab

Collab lets multiple artists on the same instance build a track together: upload stems, save version snapshots, and iterate — no separate app, no realtime, no ZEN.

Why native, not a Lab app

Collab needs rich relational data (projects, versions, permissions) and dedicated pages (list, detail, version history) — the Lab SDK is designed for stateless one-shot tools embedded via iFrame, not this. Collab is a first-class TuneCamp feature with its own tables and routes.

Data model

• collab_projects — title, description, owner_id, visibility (shared | private).
• collab_versions — append-only, never overwritten (UNIQUE(project_id, version)). Each row is a snapshot (state, opaque JSON), authored by whoever saved it.
• collab_stems — raw in-progress audio layers, deliberately separate from tracks/samples (no publish/curation semantics).

See architecture-backend.md for the full schema list.

Permissions

Reuses the existing publishing gate — no new permission system:

• Read: requires login; visibility='shared' projects are readable by any logged-in user, private only by the owner.
• Write (create project, upload stem, save version): requires VisibilityGuardian.canPublishContent() — same gate as releases, sample packs, and every other publish endpoint.
• Delete: project creator (owner_id match) only.
• Open collaboration v1: any artist on the instance who passes canPublishContent can write to a shared project — no invite/collaborator list.

API

Method	Route	Notes
GET	/api/collab	List shared projects (?mine=true for the caller's own).
POST	/api/collab	Create a project.
GET	/api/collab/:id	Project + versions + stems.
DELETE	/api/collab/:id	Owner only.
POST	/api/collab/:id/versions	Save a version snapshot (state, optional note).
POST	/api/collab/:id/stems	Upload an audio stem (multipart file).
GET	/api/collab/:id/stems/:stemId/download	Stream a stem's audio.
DELETE	/api/collab/:id/stems/:stemId	Stem author or project owner.

All routes require login (authMiddleware.requireUser).

Webapp

• /collab — list shared projects, create new ones (if canPublishContent).
• /collab/:id — stems (upload/play/delete), version history, save-snapshot form.

Not (yet) realtime

No live cursors/presence — versioning (append-only rows) covers the collaboration need. Live presence is deferred to the already-planned "Phase C" ZEN-via-worker_thread-RPC work (ephemeral presence / real-time collaborative playlists) documented in the repo's session rules — Collab does not duplicate or depend on it.