-- Durable registry of the live container backing each agent (terminal / agent /
-- browser), so ANY server replica can find + reuse it instead of the former
-- in-process map (which made a 2nd replica spawn duplicate containers). node_id
-- records placement for the multi-node node-pool (Phase 2); it is 'local' today.
CREATE TABLE agent_containers (
    agent_id      UUID NOT NULL REFERENCES agents (id) ON DELETE CASCADE,
    kind          TEXT NOT NULL,                 -- 'terminal' | 'agent' | 'browser'
    node_id       TEXT NOT NULL DEFAULT 'local',
    container_id  TEXT NOT NULL,
    name          TEXT NOT NULL,
    workspace_id  UUID NOT NULL REFERENCES workspaces (id) ON DELETE CASCADE,
    session_count INTEGER NOT NULL DEFAULT 0,    -- live attached sessions (terminals)
    created_at    TIMESTAMPTZ NOT NULL DEFAULT now(),
    last_seen     TIMESTAMPTZ NOT NULL DEFAULT now(),
    PRIMARY KEY (agent_id, kind)
);
CREATE INDEX agent_containers_idle_idx ON agent_containers (kind, last_seen);