-- spec.sr.ht full initial schema.
--
-- This is the authoritative DDL for a fresh install. The brant migration in
-- migrations/0001_initial.sql applies the same objects incrementally; keep the
-- two in sync.
--
-- Git is authoritative for document bodies; Postgres never stores a body. Every
-- table here holds only what git cannot answer cheaply, and every table here is
-- reconstructable from refs by the reconciler — which is what makes the
-- non-transactional merge path (git refs, then Postgres, then the index)
-- tolerable.
--
-- Deliberately absent: `comment` (inline comments are post-v1, and the
-- anchoring model should be settled by building the review UI before it is
-- committed to a schema).

-- Spaces exist as repos; this table is for listing and index bookkeeping.
CREATE TABLE space (
	id            SERIAL PRIMARY KEY,
	owner         TEXT NOT NULL,          -- "bigbes", no ~ prefix
	name          TEXT NOT NULL,
	created       TIMESTAMPTZ NOT NULL DEFAULT now(),
	CONSTRAINT uq_space_owner_name UNIQUE (owner, name)
);

-- Global, not per-project: a later import cannot collide. doc_id is the PRIMARY
-- KEY rather than a (space_id, doc_id) pair on purpose — global uniqueness is
-- the invariant the whole link/comment/staleness model rests on, so a colliding
-- registration must be impossible to insert, not merely detected in Go.
CREATE TABLE document_id (
	doc_id        TEXT PRIMARY KEY,       -- "SPEC-0007"
	space_id      INTEGER NOT NULL REFERENCES space(id) ON DELETE CASCADE,
	path          TEXT NOT NULL,          -- current path on the approved branch
	updated_rev   TEXT NOT NULL
);

CREATE TABLE proposal (
	id            SERIAL PRIMARY KEY,
	space_id      INTEGER NOT NULL REFERENCES space(id) ON DELETE CASCADE,
	title         TEXT NOT NULL,
	rationale     TEXT,
	base_rev      TEXT NOT NULL,          -- the If-Match value; does not move
	branch        TEXT NOT NULL,          -- "proposals/42"
	state         TEXT NOT NULL,          -- open | merged | rejected
	approval      TEXT,                   -- human | policy, set on merge
	merged_rev    TEXT,
	agent         TEXT NOT NULL,          -- "claude-code/spec-writer"
	agent_session TEXT NOT NULL,
	created       TIMESTAMPTZ NOT NULL DEFAULT now(),
	resolved      TIMESTAMPTZ,

	-- The state machine is `open -> merged` and `open -> rejected`, and nothing
	-- else. These constraints make every row that would contradict it
	-- unwritable; the UPDATE ... WHERE state = 'open' guard in db/proposal.go
	-- is what makes an illegal *transition* unwritable.
	CONSTRAINT ck_proposal_state CHECK (state IN ('open', 'merged', 'rejected')),
	CONSTRAINT ck_proposal_approval CHECK (approval IS NULL OR approval IN ('human', 'policy')),
	-- Auto-merged is not human-approved and readers must be able to tell, so a
	-- merged row without an approval kind (or an unmerged row carrying one)
	-- would launder unreviewed agent output as blessed.
	CONSTRAINT ck_proposal_merged CHECK ((state = 'merged') = (approval IS NOT NULL)),
	CONSTRAINT ck_proposal_merged_rev CHECK ((state = 'merged') = (merged_rev IS NOT NULL)),
	CONSTRAINT ck_proposal_resolved CHECK ((state = 'open') = (resolved IS NULL)),
	-- Provenance is the one thing that is not optional: one shared token still
	-- yields a full audit trail because the identity strings, not the
	-- credential, are what identify who did what. NOT NULL alone would accept
	-- the empty string and lose that.
	CONSTRAINT ck_proposal_provenance CHECK (length(agent) > 0 AND length(agent_session) > 0)
);
-- The inbox ("N proposals waiting on you") and the digest are both
-- state-filtered, newest-first scans.
CREATE INDEX ix_proposal_state_created ON proposal (state, created DESC);

-- Only a hash is ever stored; the token itself exists exactly once, at mint
-- time, in the response to the operator.
CREATE TABLE agent_token (
	id            SERIAL PRIMARY KEY,
	name          TEXT NOT NULL,
	token_hash    BYTEA NOT NULL UNIQUE,
	created       TIMESTAMPTZ NOT NULL DEFAULT now(),
	revoked       TIMESTAMPTZ
);

-- Index staleness: compared against the space's approved head.
CREATE TABLE index_stamp (
	space_id      INTEGER PRIMARY KEY REFERENCES space(id) ON DELETE CASCADE,
	rev           TEXT NOT NULL,
	indexed_at    TIMESTAMPTZ NOT NULL DEFAULT now()
);

-- "What landed since you last looked", for the policy-merged digest.
CREATE TABLE digest_mark (
	owner         TEXT PRIMARY KEY,
	seen_at       TIMESTAMPTZ NOT NULL
);

-- A project is pure metadata: a saved filter, not a container. It owns no index
-- and no storage, so this table is a name and the next one is the filter.
--
-- There is exactly one bleve index; querying a project means restricting that
-- index to the project's spaces. Per-project indexes were specified in an
-- earlier draft and retracted: every merge would fan out to N rebuilds and
-- adding a space to a project would force one. Nothing here scopes document
-- IDs either — those are global (see document_id above), because projects are
-- edited *after* merges, so a per-project registry could juxtapose two
-- already-merged documents sharing an ID with no merge left to reject.
CREATE TABLE project (
	id            SERIAL PRIMARY KEY,
	owner         TEXT NOT NULL,          -- "bigbes", no ~ prefix
	name          TEXT NOT NULL,          -- "tarantool", no + prefix
	created       TIMESTAMPTZ NOT NULL DEFAULT now(),
	CONSTRAINT uq_project_owner_name UNIQUE (owner, name)
);

-- The filter itself: which spaces a project selects. The composite primary key
-- is what makes membership a set — a space cannot be added to a project twice,
-- so no query has to deduplicate — and it is also the index for resolving a
-- project to its spaces. Both sides cascade: deleting a project drops its
-- membership rows and nothing else, and deleting a space removes it from every
-- project that named it rather than leaving a dangling filter term.
CREATE TABLE project_space (
	project_id    INTEGER NOT NULL REFERENCES project(id) ON DELETE CASCADE,
	space_id      INTEGER NOT NULL REFERENCES space(id) ON DELETE CASCADE,
	PRIMARY KEY (project_id, space_id)
);
-- The other direction: which projects contain this space. Not covered by the
-- primary key, whose leading column is project_id.
CREATE INDEX ix_project_space_space ON project_space (space_id);