-- Loops: durable recurring topology executions. A loop pairs a stored
-- topology graph + task template with a trigger configuration (any of
-- cron / on_completion / webhook) and a repeat policy (infinite / N iters /
-- until condition). Every iteration writes a normal topology_runs row with
-- loop_id + iteration + parent_run_id set so the existing SSE observer,
-- audit log, and gated approvals surface transparently.
--
-- Cross-iteration state: iteration N+1's run driver reads parent_run_id and
-- injects the parent's final assistant message into the first system prompt
-- as prior-iteration context (refine-over-time by default).
--
-- Missed schedules: if the loop scheduler wakes and finds next_fire_at in
-- the past (a restart or long stall), it fires ONCE and computes the next
-- fire from the current cron expression. Missed backlog is not drained.

CREATE TABLE loops (
    id             UUID PRIMARY KEY,
    workspace_id   UUID NOT NULL REFERENCES workspaces (id) ON DELETE CASCADE,
    title          TEXT NOT NULL,
    description    TEXT NOT NULL,
    -- Same shape as topology_runs.graph: JSON-encoded agent/node connectivity
    -- from the wizard's topology builder (or a template pick).
    graph          JSONB NOT NULL,
    -- Text prompt used as the task for every iteration. Templating is out of
    -- scope for v1 — the same string runs each time (with prior-iteration
    -- output prepended by the run driver for refine-over-time).
    task_template  TEXT NOT NULL,
    -- {cron?: '0 */6 * * *', on_completion?: bool, webhook_enabled?: bool}
    -- All three can be enabled simultaneously; whichever fires first wins.
    triggers       JSONB NOT NULL DEFAULT '{}'::JSONB,
    -- {kind: 'infinite' | 'iters' | 'until', spec: <kind-specific>}
    --   iters: {n: 10}                — stop after N iterations
    --   until: {event: 'ok', within_iters: 20} — stop when N events match
    repeat_policy  JSONB NOT NULL DEFAULT '{"kind":"infinite"}'::JSONB,
    enabled        BOOLEAN NOT NULL DEFAULT true,
    -- Computed by the scheduler from `triggers.cron` after each fire. NULL
    -- when no cron trigger is set (loop runs only on webhook / on_completion
    -- / manual).
    next_fire_at   TIMESTAMPTZ,
    last_run_id    UUID REFERENCES topology_runs (id) ON DELETE SET NULL,
    -- Opaque secret ID for the webhook endpoint. HMAC-SHA256 verification of
    -- the request body uses webhook_signing_key. Both are NULL when the
    -- webhook trigger is disabled; both are set when it's on. Rotation:
    -- disable trigger, re-enable to regenerate both.
    webhook_token        TEXT UNIQUE,
    webhook_signing_key  TEXT,
    created_by     UUID NOT NULL REFERENCES users (id) ON DELETE RESTRICT,
    created_at     TIMESTAMPTZ NOT NULL DEFAULT now(),
    updated_at     TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE INDEX loops_workspace_idx
    ON loops (workspace_id, updated_at DESC);
-- Scheduler tick query: SELECT ... WHERE enabled AND next_fire_at <= now().
-- Partial index keeps the scanner tight; disabled + no-cron loops stay out.
CREATE INDEX loops_next_fire_idx
    ON loops (next_fire_at)
    WHERE enabled AND next_fire_at IS NOT NULL;

-- Back-refs from durable runs. loop_id groups all iterations of a loop;
-- iteration is 1-indexed per loop; parent_run_id chains iteration N+1 back
-- to N so the run driver can pull prior context in one hop.
ALTER TABLE topology_runs
    ADD COLUMN loop_id       UUID REFERENCES loops (id) ON DELETE SET NULL,
    ADD COLUMN iteration     INT,
    ADD COLUMN parent_run_id UUID REFERENCES topology_runs (id) ON DELETE SET NULL;

-- Listing "recent iterations of loop X" hits this.
CREATE INDEX topology_runs_loop_idx
    ON topology_runs (loop_id, iteration DESC)
    WHERE loop_id IS NOT NULL;