## Why
Multi-agent v2 `send_message` deliveries already reach the receiving
model as typed `agent_message` items with encrypted content.
Child-completion notifications are generated by Codex itself, so their
content is plaintext and previously fell back to a serialized JSON
envelope inside an assistant message.
With plaintext `input_text` supported for `agent_message`, both delivery
paths can use the same model-visible type while preserving explicit
author and recipient metadata.
## What changed
- add plaintext `input_text` support to `AgentMessageInputContent` and
regenerate the affected app-server schemas
- preserve `InterAgentCommunication` as structured mailbox input instead
of converting it to assistant text
- record delivered communications as typed `agent_message` history items
- persist a dedicated rollout item so local delivery metadata such as
`trigger_turn` remains available without leaking into the Responses
request
- reconstruct typed agent messages on resume and preserve fork-turn
truncation behavior
- remove request-time assistant-content parsing
- preserve plaintext and encrypted inter-agent deliveries in stage-one
memory inputs
- normalize and link plaintext and encrypted agent messages in rollout
traces without treating inbound messages as child results
- cover the real MultiAgent V2 child-completion path end to end with
deterministic mailbox synchronization
## Verification
- `just test -p codex-core
plaintext_multi_agent_v2_completion_sends_agent_message`
- `just test -p codex-core input_queue_drains_mailbox_in_delivery_order
record_initial_history_reconstructs_typed_inter_agent_message
fork_turn_positions_use_inter_agent_delivery_metadata`
- `just test -p codex-memories-write
serializes_inter_agent_communications_for_memory`
- `just test -p codex-rollout-trace
agent_messages_preserve_routing_and_content
sub_agent_started_activity_creates_spawn_edge`
- `just test -p codex-rollout-trace
agent_result_edge_falls_back_to_child_thread_without_result_message`
- `just test -p codex-protocol -p codex-rollout -p
codex-app-server-protocol`
## Summary
- Change last-`n` fork truncation to start at the first fork-turn
boundary instead of returning the full rollout when the fork history is
shorter than the requested window.
- Add coverage for the startup-prefix case in both rollout truncation
tests and agent control spawn behavior.
- Ensure bounded forked children still rebuild context after the cached
prefix is truncated.
## Testing
- Added unit coverage for truncation behavior when the parent history is
under the requested fork-turn limit.
- Added an agent control test covering bounded fork spawn behavior with
startup context present.
- Not run (not requested).
Adds this:
```
properties.insert(
"fork_turns".to_string(),
JsonSchema::String {
description: Some(
"Optional MultiAgentV2 fork mode. Use `none`, `all`, or a positive integer string such as `3` to fork only the most recent turns."
.to_string(),
),
},
);
```
---------
Co-authored-by: Codex <noreply@openai.com>
jifandGitHub
rhan-oaiandGitHub
Ahmed IbrahimandGitHub