• [Fix] Avoid a FrozenError on Producer#close when the producer is configured with a frozen string id (for example a frozen string literal, config.id = "rspec").
• [Fix] Emit connection_pool.shutdown only once when shutting down the global connection pool.
• [Fix] Retry a produce that races a concurrent idempotent fatal-error reload instead of leaking a raw Rdkafka::ClosedProducerError/Rdkafka::ClosedInnerError.
• [Maintenance] Stop the #partition_count when topic does not exist spec from flaking on slow CI runners by waiting for authoritative broker metadata before asserting the count.