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packages/db/src/adapters/bunsql.ts

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+/**
+ * Postgres + MySQL adapters built on Bun's native SQL client (`Bun.SQL`) — no
+ * external driver dependency. Both speak the same `Driver` interface; only the
+ * dialect (and thus the DDL types + placeholder style) differ.
+ *
+ * `Bun.SQL` pools connections, so transactions use its managed `begin(fn)` to
+ * keep BEGIN/…/COMMIT on one reserved connection.
+ */
+
+import type { Dialect } from "../sql.ts";
+import type { Driver, Row, TxHandle } from "../driver.ts";
+
+interface BunSqlClient {
+  unsafe(query: string, params?: unknown[]): Promise<unknown>;
+  begin<T>(fn: (tx: BunSqlClient) => Promise<T>): Promise<T>;
+  close(): Promise<void>;
+}
+
+interface ExecMeta {
+  count?: number;
+  affectedRows?: number;
+  lastInsertRowid?: number | bigint;
+  insertId?: number | bigint;
+}
+
+function runnerFor(client: BunSqlClient): TxHandle {
+  return {
+    async query(sql, params = []): Promise<Row[]> {
+      const rows = (await client.unsafe(sql, params)) as Iterable<Row>;
+      return Array.from(rows);
+    },
+    async exec(sql, params = []) {
+      const meta = (await client.unsafe(sql, params)) as ExecMeta;
+      const id = meta.lastInsertRowid ?? meta.insertId;
+      return {
+        changes: Number(meta.affectedRows ?? meta.count ?? 0),
+        lastInsertId: id != null ? Number(id) : undefined,
+      };
+    },
+  };
+}
+
+/** Create a Bun.sql-backed driver for the given connection URL + dialect. */
+export function bunSql(url: string, dialect: Dialect): Driver {
+  const Ctor = (Bun as unknown as { SQL: new (u: string) => BunSqlClient }).SQL;
+  const client = new Ctor(url);
+  const runner = runnerFor(client);
+  return {
+    dialect,
+    query: runner.query,
+    exec: runner.exec,
+    transaction(fn) {
+      return client.begin((tx) => fn(runnerFor(tx)));
+    },
+    close() {
+      return client.close();
+    },
+  };
+}
+
+/** PostgreSQL adapter (`postgres://user:pass@host:5432/db`). Placeholders: `$N`. */
+export function postgres(url: string): Driver {
+  return bunSql(url, "postgres");
+}
+
+/** MySQL adapter (`mysql://user:pass@host:3306/db`). Placeholders: `?`. */
+export function mysql(url: string): Driver {
+  return bunSql(url, "mysql");
+}