ALTER TABLE services DROP CONSTRAINT services_available_source_check;
ALTER TABLE services ADD CONSTRAINT services_available_source_check
    CHECK (available_source IN ('', 'webhook', 'poll'));
ALTER TABLE services ADD COLUMN available_digest text NOT NULL DEFAULT '';
ALTER TABLE services ADD COLUMN last_poll_error  text NOT NULL DEFAULT '';
ALTER TABLE services ADD COLUMN last_auto_digest text NOT NULL DEFAULT '';

-- Every version the master has seen. '' means "no tag" / "digest unknown";
-- never NULL, so the unique constraint deduplicates.
CREATE TABLE image_versions (
    id            bigserial   PRIMARY KEY,
    repo          text        NOT NULL,
    tag           text        NOT NULL DEFAULT '',
    digest        text        NOT NULL DEFAULT '',
    source        text        NOT NULL CHECK (source IN ('webhook', 'poll', 'running')),
    first_seen_at timestamptz NOT NULL,
    CONSTRAINT image_versions_tag_or_digest CHECK (tag <> '' OR digest <> ''),
    CONSTRAINT image_versions_unique UNIQUE (repo, tag, digest)
);
CREATE INDEX image_versions_recent ON image_versions (repo, first_seen_at DESC, id DESC);