fix: address review findings on postgres backend

- PostgresMigrator: run JS migration parts on the transactional client
  (WrappedPgTx) instead of the pool, preserving migration atomicity
- pool.ts: guard ROLLBACK so a failing rollback no longer masks the
  original error (also applied in the migrator loop)
- pool.ts: share all/get/run between WrappedPool and WrappedPgTx via a
  common base class
- sql.ts: document that toPositional precludes JSONB ?/?|/?& operators
- PostgresInterface: implement deleteSession, required by
  BackendDbInterface since the logout-invalidation change on master

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/db/postgres/PostgresInterface.ts

@@ -408,6 +408,14 @@ export class PostgresInterface implements BackendDbInterface {
     `);
   }
 
+  async deleteSession(token: `as_${string}`): Promise<void> {
+    this.#checkReadonly();
+    await this.#db.run(sql`
+      DELETE FROM "sessions"
+      WHERE "token" = ${{ text: token }}
+    `);
+  }
+
   async #getApikeyByToken(
     token: `at_${string}`,
     db: WrappedPgClient

src/db/postgres/PostgresMigrator.ts

@@ -5,7 +5,7 @@ import type {
 } from "../types/Migrator.js";
 import { init, migrations } from "./migrations/index.js";
 import { pgToDate } from "./cast.js";
-import { WrappedPool } from "./pool.js";
+import { rollbackQuietly, WrappedPgTx, WrappedPool } from "./pool.js";
 import { sql, toPositional } from "./sql.js";
 
 export class PostgresMigrator implements Migrator {
@@ -97,6 +97,7 @@ export class PostgresMigrator implements Migrator {
     for (const migration of toApply) {
       console.log(`Applying migration ${migration.id} (${migration.name})`);
       const client = await this.#pool._pool.connect();
+      const tx = new WrappedPgTx(client, false);
       try {
         await client.query("BEGIN");
         for (const part of migration.parts) {
@@ -104,7 +105,7 @@ export class PostgresMigrator implements Migrator {
           if ("sql" in part) {
             await client.query(part.sql);
           } else {
-            await part.apply(this.#pool);
+            await part.apply(tx);
           }
         }
         const recordSql = sql`
@@ -114,7 +115,7 @@ export class PostgresMigrator implements Migrator {
         await client.query(toPositional(recordSql._sql), recordSql._vars);
         await client.query("COMMIT");
       } catch (e) {
-        await client.query("ROLLBACK");
+        await rollbackQuietly(client);
         throw e;
       } finally {
         client.release();

src/db/postgres/pool.ts

@@ -29,12 +29,22 @@ async function rethrow<R>(fn: () => Promise<R>): Promise<R> {
   }
 }
 
-class WrappedPgTx implements WrappedPgClient {
-  #client: pg.PoolClient;
+// Rollback on a broken connection can itself throw; the original error is
+// the one worth surfacing.
+export async function rollbackQuietly(
+  client: pg.PoolClient
+): Promise<void> {
+  try {
+    await client.query("ROLLBACK");
+  } catch {}
+}
+
+abstract class WrappedPgBase implements WrappedPgClient {
+  #queryable: pg.Pool | pg.PoolClient;
   #readonly: boolean;
 
-  constructor(client: pg.PoolClient, readonly_: boolean) {
-    this.#client = client;
+  constructor(queryable: pg.Pool | pg.PoolClient, readonly_: boolean) {
+    this.#queryable = queryable;
     this.#readonly = readonly_;
   }
 
@@ -42,10 +52,14 @@ class WrappedPgTx implements WrappedPgClient {
     return this.#readonly;
   }
 
-  async destroy(): Promise<void> {}
+  abstract destroy(): Promise<void>;
+  abstract multi<R>(fn: (tx: WrappedPgClient) => Promise<R>): Promise<R>;
 
   async all<R>(stmt: SqlCode): Promise<R[]> {
-    const result = await this.#client.query(toPositional(stmt._sql), stmt._vars);
+    const result = await this.#queryable.query(
+      toPositional(stmt._sql),
+      stmt._vars
+    );
     return result.rows as R[];
   }
 
@@ -56,72 +70,61 @@ class WrappedPgTx implements WrappedPgClient {
   }
 
   async run(stmt: SqlCode): Promise<{ changes: number }> {
-    const result = await this.#client.query(toPositional(stmt._sql), stmt._vars);
+    const result = await this.#queryable.query(
+      toPositional(stmt._sql),
+      stmt._vars
+    );
     return { changes: result.rowCount ?? 0 };
   }
 
-  multi<R>(_fn: (tx: WrappedPgClient) => Promise<R>): Promise<R> {
-    throw new Error("Nested transactions not supported");
-  }
-
   rethrow = rethrow;
 }
 
-export class WrappedPool implements WrappedPgClient {
+export class WrappedPgTx extends WrappedPgBase {
+  constructor(client: pg.PoolClient, readonly_: boolean) {
+    super(client, readonly_);
+  }
+
+  async destroy(): Promise<void> {}
+
+  multi<R>(_fn: (tx: WrappedPgClient) => Promise<R>): Promise<R> {
+    throw new Error("Nested transactions not supported");
+  }
+}
+
+export class WrappedPool extends WrappedPgBase {
   #pool: pg.Pool;
-  #readonly: boolean;
 
   constructor(connectionStringOrPool: string | pg.Pool, readonly_ = false) {
-    this.#pool =
+    const pool =
       typeof connectionStringOrPool === "string"
         ? new pg.Pool({ connectionString: connectionStringOrPool })
         : connectionStringOrPool;
-    this.#readonly = readonly_;
+    super(pool, readonly_);
+    this.#pool = pool;
   }
 
   get _pool(): pg.Pool {
     return this.#pool;
   }
 
-  get readonly(): boolean {
-    return this.#readonly;
-  }
-
   async destroy(): Promise<void> {
     await this.#pool.end();
   }
 
-  async all<R>(stmt: SqlCode): Promise<R[]> {
-    const result = await this.#pool.query(toPositional(stmt._sql), stmt._vars);
-    return result.rows as R[];
-  }
-
-  async get<R>(stmt: SqlCode): Promise<R | null> {
-    const rows = await this.all<R>(stmt);
-    if (rows.length > 1) throw new Error("Multiple results");
-    return rows[0] ?? null;
-  }
-
-  async run(stmt: SqlCode): Promise<{ changes: number }> {
-    const result = await this.#pool.query(toPositional(stmt._sql), stmt._vars);
-    return { changes: result.rowCount ?? 0 };
-  }
-
   async multi<R>(fn: (tx: WrappedPgClient) => Promise<R>): Promise<R> {
     const client = await this.#pool.connect();
-    const tx = new WrappedPgTx(client, this.#readonly);
+    const tx = new WrappedPgTx(client, this.readonly);
     try {
       await client.query("BEGIN");
       const result = await fn(tx);
       await client.query("COMMIT");
       return result;
     } catch (e) {
-      await client.query("ROLLBACK");
+      await rollbackQuietly(client);
       throw e;
     } finally {
       client.release();
     }
   }
-
-  rethrow = rethrow;
 }

src/db/postgres/sql.ts

@@ -73,6 +73,9 @@ export function calcUpdates<T extends object>(updater: {
   };
 }
 
+// Rewrites every literal `?` into a numbered placeholder, so queries must
+// not contain Postgres's JSONB `?` / `?|` / `?&` operators (use
+// `jsonb_exists`, `jsonb_exists_any`, `jsonb_exists_all` instead).
 export function toPositional(sql: string): string {
   let i = 0;
   return sql.replace(/\?/g, () => `$${++i}`);