[Bug]: #24850 reverses #24560: re-checks can no longer continue the same reviewer #24877

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. Run v0.1.3-nightly.20261025.3669 (includes feat(server): cut T3's agent instructions and tool copy by 60% #24850).
2. A parent agent delegates a review with delegate_task; the reviewer returns a must-fix finding and the author fixes it.
3. The parent needs that same reviewer to re-check the fix.

Expected behavior

As in #24560 (which fixed #19821): independent review rounds start a fresh delegate_task, while a same-scope re-check that needs the reviewer's own context continues the reviewer with t3_thread_send on its childThreadId. t3_thread_send still supports this path: a follow-up to a completed child starts a new tracked task, returns its taskId, and notifies the parent.

Actual behavior

#24850 replaced that distinction with:

Every new delegate review or re-check is a new delegate_task (brief, findings, objections), never a t3_thread_send.

and added tests that assert it (CodexDeveloperInstructions.test.ts, McpHttpServer.test.ts). So every re-check now has to go to a fresh reviewer, which re-reads the whole change and loses the context it used to raise the findings it is checking, plus the parent's prompt cache for that child. This reverses #24560 one day after it merged.

We agree with the other half of the same line ("Fix small review findings yourself; start no delegate for them"): skipping re-checks for small findings is a good change. This report is only about how a re-check that is still needed reaches the reviewer.

Could the guidance keep the #24560 distinction, or make this configurable? If agents were misusing t3_thread_send for independent reviews, keeping the distinction seems a narrower fix than banning the path.

Impact

Minor bug or occasional failure

Version or commit

v0.1.3-nightly.20261025.3669 (5f64c5e); regresses #24560 (909e4c9)

Environment

Windows 11, T3 Code desktop nightly; Claude Opus 5.5 parent delegating reviews to Codex GPT-6.1 Sol.

Workaround

Stay on v0.1.3-nightly.20261025.3655, or override the rule in user-level agent instructions.