codex/agentydragon/tasks/25-guard-tool-output-sequencing-rust.md

id: 25 title: Guard Against Missing Tool Output in Rust Server Sequencing status: Not started # one of: Not started, Started, Needs manual review, Done, Cancelled summary: Prevent out-of-order chat messages and missing tool output errors when user input interrupts tool execution in the Rust backend. goal: | Ensure the Rust server implementation sequences tool output and chat messages correctly. Add synchronization logic so that an in-flight tool invocation either completes or is cancelled before new messages are processed, avoiding "No tool output found" invalid_request errors. ## Acceptance Criteria - The Rust message broker must detect pending tool invocations and pause delivery of subsequent user or model messages until the tool result or cancellation is handled. - No panic or 400 Bad Request errors should occur due to missing tool output in edge cases of interrupted rollouts or mid-stream user input. - Add Rust integration tests simulating tool invocation interruption and user message interleaving, verifying correct ordering and delivery. ## Implementation How it was implemented
- Introduce a pending-invocation registry (HashMap<InvocationId, PendingState>) in the Rust message pipeline. - Modify handle_user_message and handle_model_event in the broker to check for unresolved pending invocations and enqueue incoming events accordingly. - On receiving the corresponding tool output or tool abort event, dequeue and dispatch any buffered messages in order. - Implement a timeout or explicit cancel path to avoid stuck invocations in case of unresponsive tools. - Extend the Rust test suite (e.g. in broker/tests/) with scenarios covering normal, aborted, and concurrent messages. ## Notes - Mirror the JS implementation guard patterns for consistency across backends. - Provide clear logging at the debug level to trace sequencing steps during development.