-- Chat-side pin of the agent's latest pushed context snapshot
-- (workspace_agent_context_snapshots). Written by hydration (chat
-- create and agent push) and the dirty fan-out, and re-pinned by the
-- refresh endpoint. These columns are dark plumbing: they do not feed
-- prompt building and the per-turn context pull is unchanged. They are
-- read by drift detection and the refresh endpoint only.
ALTER TABLE chats
    ADD COLUMN context_aggregate_hash bytea,
    ADD COLUMN context_dirty_since timestamptz,
    ADD COLUMN context_dirty_resources jsonb,
    ADD COLUMN context_error text NOT NULL DEFAULT '';

COMMENT ON COLUMN chats.context_aggregate_hash IS 'Aggregate hash of the agent context snapshot this chat is pinned to. NULL until first hydrated; compared against the agent''s latest snapshot hash to detect drift.';
COMMENT ON COLUMN chats.context_dirty_since IS 'Set when an agent push changes the pinned hash; cleared on refresh. NULL means clean.';
COMMENT ON COLUMN chats.context_dirty_resources IS 'Deterministic prefix of resources that changed since the pinned hash. Reserved for the dirty diff; left NULL until the UI phase populates it.';
COMMENT ON COLUMN chats.context_error IS 'Snapshot-level error copied from the pinned snapshot (count cap exceeded, watcher degraded, etc.). Empty when healthy.';

-- Refresh chats_expanded to include the new chat columns. The gentest
-- TestViewSubsetChat requires every chats column to appear in the view.
-- Drop and recreate because a view cannot have columns inserted in the
-- middle of its column list.
DROP VIEW IF EXISTS chats_expanded;
CREATE VIEW chats_expanded AS
 SELECT c.id,
    c.owner_id,
    c.workspace_id,
    c.title,
    c.status,
    c.worker_id,
    c.started_at,
    c.heartbeat_at,
    c.created_at,
    c.updated_at,
    c.parent_chat_id,
    c.root_chat_id,
    c.last_model_config_id,
    c.archived,
    c.last_error,
    c.mode,
    c.mcp_server_ids,
    c.labels,
    c.build_id,
    c.agent_id,
    c.pin_order,
    c.last_read_message_id,
    c.last_injected_context,
    c.dynamic_tools,
    c.organization_id,
    c.plan_mode,
    c.client_type,
    c.last_turn_summary,
    c.snapshot_version,
    c.history_version,
    c.queue_version,
    c.generation_attempt,
    c.retry_state,
    c.retry_state_version,
    c.runner_id,
    c.requires_action_deadline_at,
    COALESCE(root.user_acl, c.user_acl) AS user_acl,
    COALESCE(root.group_acl, c.group_acl) AS group_acl,
    owner.username AS owner_username,
    owner.name AS owner_name,
    c.context_aggregate_hash,
    c.context_dirty_since,
    c.context_dirty_resources,
    c.context_error
   FROM ((chats c
     LEFT JOIN chats root ON ((root.id = COALESCE(c.root_chat_id, c.parent_chat_id))))
     JOIN visible_users owner ON ((owner.id = c.owner_id)));