-- Agent Workbench sessions: per-session token / cost accounting and metadata.
--
-- One row per agent conversation session. Token counts and cost accumulate
-- across the turns of a session; `updated_at` advances on every `/api/agent/chat`
-- round-trip. `user_id` is nullable so admin (global-token) sessions are allowed
-- without a user row, but every session is still isolated by its own sandbox
-- directory keyed on `id`.
CREATE TABLE IF NOT EXISTS agent_sessions (
    id              TEXT PRIMARY KEY NOT NULL,
    user_id         INTEGER,
    title           TEXT,
    model           TEXT NOT NULL DEFAULT '',
    permission_mode TEXT NOT NULL DEFAULT 'default',
    input_tokens    INTEGER NOT NULL DEFAULT 0,
    output_tokens   INTEGER NOT NULL DEFAULT 0,
    total_tokens    INTEGER NOT NULL DEFAULT 0,
    cost_usd        REAL NOT NULL DEFAULT 0,
    num_turns       INTEGER NOT NULL DEFAULT 0,
    message_count   INTEGER NOT NULL DEFAULT 0,
    created_at      TEXT NOT NULL DEFAULT (datetime('now')),
    updated_at      TEXT NOT NULL DEFAULT (datetime('now'))
);

CREATE INDEX IF NOT EXISTS agent_sessions_user_id_idx
    ON agent_sessions (user_id);

CREATE INDEX IF NOT EXISTS agent_sessions_updated_at_idx
    ON agent_sessions (updated_at);