fix(executor): propagate complete_turn failure instead of silent warn

[majiayu000]

Summary

• Fixes complete_turn 失败仅 warn，违反 U-29 禁止静默降级 #626: complete_turn failure was only logged as warn, leaving the turn state inconsistent
• Upgrades to tracing::error! with structured thread_id and turn_id fields
• Calls mark_turn_failed to properly mark the turn failed, persist thread state, and emit TurnCompleted{Failed} notification
• Eliminates the silent degradation that violated U-29

Test plan

• cargo fmt --all — clean
• cargo clippy --workspace --all-targets -- -D warnings — clean
• cargo test -p harness-server — all 5 turn lifecycle tests pass

[gemini-code-assist]

Code Review

This pull request enhances error handling in the run_turn_lifecycle function by logging detailed error information and explicitly marking turns as failed when completion fails. The review feedback suggests improving consistency with other error handling paths by recording an error item in the thread history and persisting the thread state before marking the turn as failed.

[gemini-code-assist]

To maintain consistency with the error handling logic used when the agent execution itself fails (lines 319-343), consider adding an error item to the turn history and persisting the thread state before marking the turn as failed. This ensures that the system failure during the completion phase is recorded in the thread's item history, providing better visibility in the UI and audit logs.

            Err(err) => {
                let error_msg = err.to_string();
                tracing::error!(
                    thread_id = %thread_id,
                    turn_id = %turn_id,
                    "failed to complete turn after execution: {error_msg}"
                );
                if let Err(e) = server.thread_manager.add_item(
                    &thread_id,
                    &turn_id,
                    harness_core::types::Item::Error {
                        code: -1,
                        message: format!("Failed to complete turn: {error_msg}"),
                    },
                ) {
                    tracing::warn!("failed to add error item to turn: {e}");
                } else {
                    persist_runtime_thread(&thread_db, &server, &thread_id).await;
                }
                mark_turn_failed(
                    &server,
                    &thread_db,
                    &notify_tx,
                    &notification_tx,
                    &thread_id,
                    &turn_id,
                    error_msg,
                )
                .await;
            }

[majiayu000]

/gemini review

[gemini-code-assist]

Warning

You have reached your daily quota limit. Please wait up to 24 hours and I will start processing your requests again!

[github-actions]

/gemini review

[github-actions]

/gemini review

[github-actions]

/gemini review