-- v1.1.5: filesystem-backed blob storage. The row holds metadata +
-- the SHA-256 checksum; the blob bytes live on disk at
--   <PICLOUD_FILES_ROOT>/files/<app_id>/<collection>/<id[0:2]>/<id>
-- (never in Postgres). Identity tuple is (app_id, collection, id) per
-- docs/sdk-shape.md, matching KV/docs collection scoping.
--
-- The checksum is computed in a single pass during the atomic write and
-- re-verified on read (FilesError::Corrupted on mismatch). Per-app
-- quotas are deferred to v1.2; only the per-file size cap is enforced
-- (in the service, not the schema).
CREATE TABLE files (
    app_id          UUID NOT NULL REFERENCES apps(id) ON DELETE CASCADE,
    collection      TEXT NOT NULL,
    id              UUID NOT NULL,
    name            TEXT NOT NULL,
    content_type    TEXT NOT NULL,
    size_bytes      BIGINT NOT NULL,
    checksum_sha256 TEXT NOT NULL,           -- hex, 64 chars, lowercase
    created_at      TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at      TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    PRIMARY KEY (app_id, collection, id)
);

-- List + cursor pagination scans by (app_id, collection).
CREATE INDEX idx_files_app_collection ON files (app_id, collection);