-- Publish approval gate for research topics. Distinct from the existing
-- `approvals` table (0001), which is tightly coupled to gated tool calls
-- inside an agent run (session_key + run_id + action_type + category +
-- payload + preview + requested_by_agent, all NOT NULL). None of those apply
-- to a publish-of-a-static-topic gate; forcing them nullable would ripple
-- through cm_safety, so we give publish approvals their own small table.
--
-- Lifecycle:
--   1. Topic reaches `reviewing` (either the orchestrator flipped it after
--      the last agent run completed, or the user hit /submit-review).
--   2. A workspace member calls /api/research/:id/request-publish, which
--      writes a row here with status='pending'.
--   3. Another workspace member (any user in the workspace; per-role gating
--      can layer on later) approves or rejects.
--   4. On the first approval, the topic transitions `reviewing → publishing`
--      and (after any artifact assembly) `publishing → published`.
--   5. On a reject, the topic stays in `reviewing` and a new request is
--      allowed. Old rejected rows are audit history.

CREATE TABLE research_publish_approvals (
    id            UUID PRIMARY KEY,
    workspace_id  UUID NOT NULL REFERENCES workspaces (id) ON DELETE CASCADE,
    topic_id      UUID NOT NULL REFERENCES research_topics (id) ON DELETE CASCADE,
    requested_by  UUID NOT NULL REFERENCES users (id) ON DELETE RESTRICT,
    status        TEXT NOT NULL DEFAULT 'pending'
        CHECK (status IN ('pending', 'approved', 'rejected')),
    decided_by    UUID REFERENCES users (id) ON DELETE RESTRICT,
    decided_at    TIMESTAMPTZ,
    created_at    TIMESTAMPTZ NOT NULL DEFAULT now()
);

-- Sidebar "pending approvals" list query.
CREATE INDEX research_publish_approvals_pending_idx
    ON research_publish_approvals (workspace_id, created_at DESC)
    WHERE status = 'pending';

-- Look up "does this topic already have a pending approval?" before letting
-- a caller create a second one.
CREATE INDEX research_publish_approvals_topic_pending_idx
    ON research_publish_approvals (topic_id)
    WHERE status = 'pending';