Codex runtime: duplicate Lark DM replies

[voyax]

Summary

When running on the Codex runtime, the bot sends duplicate replies to the same Lark DM message.

Reported Behavior

• User sends a single DM in Lark
• Bot replies with the same response twice
• This happens consistently, not just occasionally

Environment

• Runtime: Codex
• Channel: Lark DM
• Agent type: zylos

Possible Causes

1. C4 dispatcher delivering the same message twice: The inbound message may be queued and delivered to the Codex session twice (e.g., retry logic treating a slow ack as a failure)
2. Codex processing the message twice: The Codex session may process the same prompt twice due to context/session handling
3. Send script called twice: The outbound c4-send.js may be invoked twice for the same response (e.g., both a streaming partial and a final response)
4. Lark component dedup failure: The Lark component's processedMessages map may fail to deduplicate under certain timing conditions with Codex's processing model

Next Steps

• Check c4-dispatcher logs for duplicate delivery of the same inbound message
• Check Codex session logs for duplicate prompt processing
• Check Lark outbound logs for duplicate send calls
• Verify the processedMessages dedup window (currently 10 minutes, 500 entries max) is sufficient

Workaround

None known yet. Need on-site debugging to identify the exact duplication point.