[Bug]: Review-round rule contradicts `t3_thread_send` on continuing a child#19821

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/server

Steps to reproduce

1. In a Codex thread (GPT-6.1-Sol), ask the agent for a three-round review in which each round must remember the last. Ask it to start the reviewer with delegate_task, and to continue the same reviewer with t3_thread_send to its childThreadId.
2. Do the same in a Claude thread (Opus 5.5) with the same prompt.
3. Check which tool each parent uses for rounds 2 and 3, and whether the reviewer remembers earlier rounds.

Expected behavior

Both parents send rounds 2 and 3 to the same child thread, and the reviewer keeps its memory. That is what t3_thread_send's description says to do: "For a follow-up that needs the same child's conversation, send to its childThreadId" (tools.ts#L238)

Since #17696, each follow-up gets its own task, status and notification. Since #16002, task_cancel on the first task stops later follow-ups too, which removes the misleading cancellation that #15115 added this rule to avoid.

Actual behavior

• The Claude parent used t3_thread_send, and the reviewer remembered earlier rounds.
• The Codex parent started a fresh delegate_task for each round, and the reviewer had no memory. It said T3's instructions override the prompt. Those instructions say to start every review round with a fresh delegate_task and not to use t3_thread_send on childThreadId. The rule appears in orchestrationInstructions.ts#L11 and in delegate_task's description (tools.ts#L68).

That rule came from #15115, before follow-ups had their own tasks, and was never narrowed to independent review rounds. Narrowing it to match t3_thread_send would fix this.

Impact

Minor bug or occasional failure

Version or commit

0.0.46-nightly.20261013.3080

Environment

macOS

Logs or stack traces

Screenshots, recordings, or supporting files

No response

Workaround

No response