Tasks assignment and Activity

Task execution ownership and display identity are intentionally separate:

• user: a human; the authenticated user hash identifies the assignee.
• openmates: native OpenMates execution; identity is openmates and the UI displays OpenMates.
• external_ai: execution outside OpenMates; the allowlisted identity is codex, displayed as Codex.
• unassigned: no current owner.

Only openmates Tasks participate in native queue admission or capacity accounting. Codex creates external_ai/codex Tasks atomically with encrypted external-chat context. Work that the user must personally perform remains user-assigned.

Activity is an append-oriented Task-scoped stream. User and agent updates reuse comment_added; deletion replaces comment content with a tombstone. The database mutation boundary automatically adds lifecycle_update rows for creation and real status transitions, including safe previous_status and next_status values. This keeps lifecycle history consistent across web, CLI, SDK, and automation callers.

Comment text is encrypted directly with the Task key. Every encryption uses a fresh AES-GCM nonce and versioned AAD containing the Task and Activity entry IDs. Embed-key material uses the same Task key but an independent nonce and distinct AAD domain. The obsolete per-comment wrapped entry key is not stored because Activity was unreleased and needs no compatibility path.