Codex prompts project twice since #3884 #3998

Summary

Since #3884 (a2a0cb1, released in v1.0.0-beta.87), every Codex user prompt is stored as two session messages. lcm_load_session returns the prompt twice, and the session database search returns it twice. Legacy rollouts that pair an agent_message event with an assistant response_item also duplicate the reply.

Cause

Codex writes one message as two records in the same turn:

• a response_item with payload.type: "message" and role user or assistant, and
• an event_msg with the same text: item_completed / UserMessage for prompts in current rollouts, or the legacy user_message and agent_message.

9d1f430 kept the response_item user message out of projection because item_completed already records it. #3884 made every user and assistant response_item message a canonical Message so import counts match the raw file. Projection is per record, so both records now become turns. The test change in #3995 asserts that both turns exist.

Evidence (record kinds and counts only)

A read-only census of local Codex rollouts:

The prompt pairs have different native ids. They share the turn id (payload.turn_id on the event, internal_chat_message_metadata_passthrough.turn_id on the response_item). Current rollouts write replies as item_completed / AgentMessage followed by an assistant response_item. Capture leaves AgentMessage unsupported, so current replies project once.

Most user response_item messages with no event are subagent prompts, which only exist in that form. Keeping them searchable was the goal of #3884.

Reproduced through the real import path:

• The runtime acceptance test that admits a current-shape rollout gets three session messages for one prompt and one reply: the prompt twice and the reply once.
• MCP lcm_load_session over the same rollout returns the prompt twice.

Expected

Each prompt and reply is one logical turn in projection, lcm_load_session and search. Capture keeps both records and their provenance. Stores that already hold both rows converge without a reset.