Add Haskell MVP BFF with mutation protocol and local compose stack.

sql/001_schema.sql

@@ -0,0 +1,61 @@
+-- Durable quota and mutation protocol state for Nuthatch.
+
+CREATE TABLE IF NOT EXISTS pools (
+    pool_id      TEXT PRIMARY KEY,
+    limit_bytes  BIGINT NOT NULL CHECK (limit_bytes > 0),
+    used_bytes   BIGINT NOT NULL DEFAULT 0 CHECK (used_bytes >= 0),
+    reserved_bytes BIGINT NOT NULL DEFAULT 0 CHECK (reserved_bytes >= 0)
+);
+
+INSERT INTO pools (pool_id, limit_bytes, used_bytes, reserved_bytes)
+VALUES ('shared', 10737418240, 0, 0)
+ON CONFLICT (pool_id) DO NOTHING;
+
+CREATE TABLE IF NOT EXISTS mutations (
+    user_id           TEXT NOT NULL,
+    kind              TEXT NOT NULL CHECK (kind IN ('put', 'delete')),
+    operation_id      TEXT NOT NULL,
+    pool_id           TEXT NOT NULL REFERENCES pools (pool_id),
+    object_key        TEXT NOT NULL,
+    relative_path     TEXT NOT NULL,
+    declared_size     BIGINT NOT NULL CHECK (declared_size >= 0),
+    content_sha256    TEXT,
+    prior_size        BIGINT NOT NULL CHECK (prior_size >= 0),
+    prior_sha256      TEXT,
+    growth_bytes      BIGINT NOT NULL CHECK (growth_bytes >= 0),
+    state             TEXT NOT NULL CHECK (
+                        state IN ('prepared', 'applying', 'succeeded', 'failed', 'rejected')
+                      ),
+    external_state    TEXT NOT NULL DEFAULT 'idle' CHECK (
+                        external_state IN ('idle', 'pending', 'settled')
+                      ),
+    created_at        TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at        TIMESTAMPTZ NOT NULL DEFAULT now(),
+    PRIMARY KEY (user_id, kind, operation_id)
+);
+
+CREATE INDEX IF NOT EXISTS mutations_active_key_idx
+    ON mutations (object_key)
+    WHERE state IN ('prepared', 'applying');
+
+CREATE INDEX IF NOT EXISTS mutations_active_idx
+    ON mutations (state)
+    WHERE state IN ('prepared', 'applying');
+
+CREATE TABLE IF NOT EXISTS key_locks (
+    object_key   TEXT PRIMARY KEY,
+    user_id      TEXT NOT NULL,
+    kind         TEXT NOT NULL,
+    operation_id TEXT NOT NULL,
+    acquired_at  TIMESTAMPTZ NOT NULL DEFAULT now(),
+    FOREIGN KEY (user_id, kind, operation_id)
+        REFERENCES mutations (user_id, kind, operation_id)
+);
+
+CREATE TABLE IF NOT EXISTS objects_meta (
+    object_key   TEXT PRIMARY KEY,
+    pool_id      TEXT NOT NULL REFERENCES pools (pool_id),
+    size_bytes   BIGINT NOT NULL CHECK (size_bytes >= 0),
+    content_sha256 TEXT NOT NULL,
+    updated_at   TIMESTAMPTZ NOT NULL DEFAULT now()
+);