-- Agent conversations (#56): multi-turn chat with the garden assistant.
--
-- "Now do the same to the north bed" needs the previous exchange, and history
-- held only by the client would be lost on a refresh — which is exactly when
-- someone reloads to see whether the agent's change actually landed.
--
-- One conversation per (user, garden). Two people editing a shared garden get
-- separate threads: a conversation is a dialogue with one person, and merging
-- them would put words in someone's mouth.
CREATE TABLE agent_conversations (
    id         INTEGER PRIMARY KEY,
    garden_id  INTEGER NOT NULL REFERENCES gardens (id) ON DELETE CASCADE,
    user_id    INTEGER NOT NULL REFERENCES users (id)   ON DELETE CASCADE,
    created_at TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
    updated_at TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
    UNIQUE (garden_id, user_id)
);

-- Only the user/assistant TEXT of each turn is kept, not the full model
-- transcript with its tool calls. Continuity needs what was said and what came
-- back; replaying a stored tool call would be replaying a decision made against
-- a garden that has since moved on. It also keeps the schema free of majordomo's
-- message shape, which is a dependency's business, not the database's.
CREATE TABLE agent_messages (
    conversation_id INTEGER NOT NULL REFERENCES agent_conversations (id) ON DELETE CASCADE,
    id              INTEGER PRIMARY KEY,
    role            TEXT    NOT NULL CHECK (role IN ('user', 'assistant')),
    body            TEXT    NOT NULL,
    -- The change set this turn produced, so the panel can offer Undo on the
    -- message that caused it. SET NULL rather than CASCADE: losing the history
    -- entry must not delete what was said about it.
    change_set_id   INTEGER REFERENCES change_sets (id) ON DELETE SET NULL,
    created_at      TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now'))
);

CREATE INDEX idx_agent_messages_conversation ON agent_messages (conversation_id, id);