Table chat_histories {
  id uuid [pk, default: `gen_random_uuid()`]
  session_id text [not null]
  title text
  channel text
  agent_id text
  project_id uuid [ref: > projects.guid]
  messages jsonb [not null, default: `'[]'`]
  summary text
  metadata jsonb [not null, default: `'{}'`]
  created_at timestamptz [not null, default: `now()`]
  updated_at timestamptz [not null, default: `now()`]

  indexes {
    session_id
    project_id
    channel
    agent_id
    created_at
  }
}

Table tool_annotations {
  id bigserial [pk]
  tool_name text [unique, not null]
  notes text [not null, default: '']
  created_at timestamptz [not null, default: `now()`]
  updated_at timestamptz [not null, default: `now()`]
}

// Cross-file refs (for relspecgo merge)
Ref: chat_histories.project_id > projects.guid [delete: set null]