Transaction-pool pipeline `LISTEN` sends `ReadyForQuery` before `Sync`

[apkipa]

Version

v0.1.57 (main 7594279, transaction pool mode with pub/sub enabled; pub_sub_channel_size = 100)

Description

A LISTEN followed by another command in one psycopg pipeline succeeds against PostgreSQL, but the transaction-pool endpoint reports an unexpected pipeline synchronization result instead of completing the pipeline. In the extended query protocol, ReadyForQuery terminates a Sync response, not an individual command (PostgreSQL protocol flow).

Transaction mode routes Command::Listen to the local listen() path. That path calls command_complete(), which sends both CommandComplete and ReadyForQuery before the client Sync (pub_sub.rs). Session mode instead forwards LISTEN through execute().

Reproduce

Run with psycopg 3 against a direct PostgreSQL endpoint and a PgDog transaction-pool endpoint. DIRECT_DSN and PGDOG_DSN refer to those endpoints.

import logging

import psycopg


logging.getLogger("psycopg").setLevel(logging.ERROR)


def run(label, dsn):
    conn = psycopg.connect(dsn, autocommit=True)
    try:
        with conn.pipeline() as pipeline:
            with conn.cursor() as cur:
                cur.execute("LISTEN pgdog_pipeline_listen")
                cur.execute("SELECT 1")
                pipeline.sync()
        print(f"{label}: {conn.execute('SELECT 42').fetchone()}")
    except Exception as exc:
        print(f"{label}: {type(exc).__name__}: {exc}")
    finally:
        conn.close()


run("direct", DIRECT_DSN)
run("pgdog", PGDOG_DSN)

Expected behavior

Both endpoints complete the pipeline and print:

direct: (42,)
pgdog: (42,)

Actual behavior

7594279 prints:

direct: (42,)
pgdog: InternalError: unexpected result status from query: PIPELINE_SYNC