* fix(agent/comments): re-emit trigger comment id every turn + server-side parent_id guard
Resumed Claude sessions keep prior turns' tool calls in context, so a
comment-triggered task could reuse the PREVIOUS turn's --parent UUID
instead of the current trigger's. The reply landed in the wrong thread
(MUL-1125): backend stored exactly what the agent sent, but the agent
pulled a stale UUID from its own conversation memory.
Two layers of defense:
1. Extract BuildCommentReplyInstructions so daemon.buildCommentPrompt
and execenv.InjectRuntimeConfig emit the same "use this exact
--parent, do not reuse values from previous turns" block. The
per-turn prompt now carries the current TriggerCommentID, which it
previously relied on CLAUDE.md for (and CLAUDE.md isn't re-read
mid-session).
2. Handler-side guard in CreateComment: when an agent posts from inside
a comment-triggered task (X-Agent-ID + X-Task-ID, task has
TriggerCommentID), require parent_id == task.TriggerCommentID or
return 409. Assignment-triggered tasks are untouched.
* fix(agent/comments): scope parent_id guard to the task's own issue
Two issues from CI + GPT-Boy's review:
1. Guard was too broad: the CLI stamps X-Task-ID on every request, so an
agent legitimately commenting on a different issue while its current
task was comment-triggered would get 409'd with the wrong issue's
trigger comment id. Narrow the guard to fire only when the request's
issue matches the task's own issue — cross-issue agent activity
stays unblocked.
2. The integration test tried to insert a second queued task for the
same (agent, issue), which hits the idx_one_pending_task_per_issue_agent
unique index. Replace the assignment-triggered-task sub-case with a
cross-issue regression test (the scenario we now need to cover anyway):
post on issue B while X-Task-ID points at a comment-triggered task on
issue A, expect 201.
