feat: db migrations and store

app/db/migrations/001_chains.sql

@@ -0,0 +1,5 @@
+CREATE TABLE IF NOT EXISTS chains (
+    id          TEXT PRIMARY KEY,
+    name        TEXT NOT NULL,
+    created_at  REAL NOT NULL
+);

app/db/migrations/002_nodes.sql

@@ -0,0 +1,19 @@
+CREATE TABLE IF NOT EXISTS nodes (
+    id                TEXT PRIMARY KEY,
+    chain_id          TEXT NOT NULL REFERENCES chains(id) ON DELETE CASCADE,
+    parent_id         TEXT REFERENCES nodes(id) ON DELETE CASCADE,
+    audio_path        TEXT,
+    duration_s        REAL,
+    status            TEXT NOT NULL DEFAULT 'pending',
+    is_committed      INTEGER NOT NULL DEFAULT 0,
+    prompt            TEXT NOT NULL DEFAULT '',
+    energy            REAL,
+    tempo_feel        REAL,
+    density           REAL,
+    cfg_coef          REAL NOT NULL DEFAULT 3.0,
+    prompt_duration_s REAL NOT NULL DEFAULT 10.0,
+    error_msg         TEXT,
+    created_at        REAL NOT NULL
+);
+CREATE INDEX IF NOT EXISTS idx_nodes_chain_id ON nodes(chain_id);
+CREATE INDEX IF NOT EXISTS idx_nodes_parent_id ON nodes(parent_id);

app/db/store.py

@@ -0,0 +1,19 @@
+from __future__ import annotations
+import sqlite3
+from pathlib import Path
+
+_MIGRATIONS_DIR = Path(__file__).parent / "migrations"
+
+
+def get_connection(db_path: str) -> sqlite3.Connection:
+    conn = sqlite3.connect(db_path, check_same_thread=False)
+    conn.row_factory = sqlite3.Row
+    conn.execute("PRAGMA journal_mode=WAL")
+    conn.execute("PRAGMA foreign_keys=ON")
+    return conn
+
+
+def run_migrations(conn: sqlite3.Connection) -> None:
+    for migration in sorted(_MIGRATIONS_DIR.glob("*.sql")):
+        conn.executescript(migration.read_text())
+    conn.commit()

tests/test_store.py

@@ -0,0 +1,27 @@
+import sqlite3
+import tempfile
+import pytest
+from app.db.store import get_connection, run_migrations
+
+
+def test_migrations_create_tables():
+    with tempfile.NamedTemporaryFile(suffix=".db") as f:
+        conn = get_connection(f.name)
+        run_migrations(conn)
+        tables = {r[0] for r in conn.execute(
+            "SELECT name FROM sqlite_master WHERE type='table'"
+        )}
+        assert "chains" in tables
+        assert "nodes" in tables
+
+
+def test_foreign_keys_enforced():
+    with tempfile.NamedTemporaryFile(suffix=".db") as f:
+        conn = get_connection(f.name)
+        run_migrations(conn)
+        with pytest.raises(sqlite3.IntegrityError):
+            conn.execute(
+                "INSERT INTO nodes (id, chain_id, status, created_at) "
+                "VALUES ('n1', 'nonexistent', 'pending', 0.0)"
+            )
+            conn.commit()