Keep a service reply that a tool result was recorded after

[edwin-zvs]

Follow-up to #1162. Found while verifying that PR against a live interactive codex service.

Problem

A service turn whose final answer is followed by a tool result reports no reply at all:

• the poll endpoint (GET /svc/<name>/sessions/<id>) returns ready: true with reply: null
• wait_for_final (headless services) blocks until its 30-minute timeout

…while the answer is sitting in the transcript the whole time.

latest_assistant_reply walks the transcript backwards and stops at the first tool event. That's correct for the case it was written for — narration preceding a tool call is commentary, not the answer. But it also stops on a tool result that trails the answer, and harnesses don't guarantee a tool's result is recorded before the assistant text it produced. Codex flushes the reply tool's result afterwards, so the walk hit the result immediately and never reached the answer:

tool_use     construct_service_reply
message      assistant "CHARLIE"
tool_result  call_MXn6...            <- walk stopped here, reply = None

That transcript is from a real session, not a constructed one.

Fix

Skip trailing tool results until collection has actually begun. Once some answer text is in hand, a tool event is again the boundary that ends it — so a turn that stops inside a tool call still reports no reply, rather than serving pre-tool narration as the answer.

SessionEvent::ToolResult { .. } if parts.is_empty() => {}

Scope

The interactive reply path (construct_service_reply → record_reply → channel adapter) never went through this function, so Slack pushes were unaffected. What was affected:

caller	symptom
HTTP channel poll endpoint	ready: true, reply: null
wait_for_final, headless services	blocks to the 30-minute timeout

Tests

Two new cases, both pinned to real transcript shapes:

• reply_survives_a_tool_result_recorded_after_the_answer — the bug. Verified it fails on main (left: None, right: Some("CHARLIE")) and passes with the fix.
• a_turn_that_ends_inside_a_tool_call_reports_no_reply — guards the boundary the skip must not cross.

cargo test --workspace: 51 test binaries, 0 failures.

Binary

Touches crates/daemon → the relevant binary is construct.