Nebula separates metadata, blob bytes, and retrieval indexes into distinct storage layers with distinct failure domains.

Metadata DB
  repos, refs, snapshots, entries, workspaces, changesets,
  proposals, merge intents, policies, environments, integrations

Blob Store
  source bytes, binary files, encrypted private blobs,
  projection bundles, artifacts

Vector DB
  path/hash index metadata today
  future: semantic embeddings keyed by TreeSnapshotId

Merge in Nebula is modeled separately from Git. It produces a MergeResult with explicit operation records for audit and replay.

Proposal
  -> MergeIntent     # Planned composition
  -> MergeResult     # Outcome with new snapshot
  -> Ref update      # Pointer advancement
  -> Operation record # Audit trail

Release gates control when and how projections can be published. Gates can be immediate, delayed, or embargoed based on policy and approval state.

• →Immediate: Merge completes the projection immediately
• →Delayed: Scheduled release with configurable delay
• →Embargoed: Blocked until explicit release signal