docs: fix re-review findings — seat-migration obligation, evidence rule moved into the standard, first-cut family settled

Restore the ReactNode seats' pending-migration obligation the earlier
rewrite had flipped into a permanent exception; state the merged-PR/issue
evidence allowance in docs/AGENTS.md itself so the citations note defers
to the standard instead of overriding it; rewrite the one current-state
'first cut' fact and record the historical-stage-name exemption (with
indexical stamps still banned); pairs re-recorded.

.agents/notes/implemented/feature/2026-06-21-subagent-capability-seam.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/feature/2026-06-21-subagent-capability-seam.md
-2026-06-21-subagent-capability-seam.md: 72f17d7566aa982a5710e466cb4f740906ef167b
-2026-06-21-subagent-capability-seam.zh.md: 8205a6e2eab3bdaddf25b582c590034e2cf2f8dd
+2026-06-21-subagent-capability-seam.md: 28ecf985db1289ce4f80570583eac6a051cd2c0b
+2026-06-21-subagent-capability-seam.zh.md: 5f349ddcacebe66c346976b822c9dcc65bda8d18

.agents/notes/implemented/feature/2026-06-21-subagent-capability-seam.md

@@ -73,4 +73,4 @@ Registry and tool tests replace only the nondeterministic child boundary with a
 - **Recursion.** Without a bound, an in-process child can see the delegation tool and recurse. The in-process backends implement the optional absolute depth limit and scoped live-global `toolFilter`; ACP advertises both capabilities off and rejects such a request. The [subagent composition-controls Agent Note](2026-07-12-subagent-persona-tool-filter-and-depth.md) owns their exact semantics and security limits.
 - **Blocking the parent turn.** Foreground collection holds the parent's step open for the child's full duration. Background delegation uses the shared `ctx.tasks` runtime and generic `task_*` tools, the same collection mechanism as background bash; the subagent seam itself remains task-agnostic.
 - **Live progress.** Only lifecycle + the final result surface; a per-chunk child→parent update stream is deferred with the background redesign.
-- **ACP client surface.** Proxying `fs`/`terminal` from the ACP child back to the parent (a shared-workspace mode) is future work; the first cut advertises neither, so the child self-serves in its own process.
+- **ACP client surface.** Proxying `fs`/`terminal` from the ACP child back to the parent (a shared-workspace mode) is future work; the backend advertises neither capability, so the child self-serves in its own process.

.agents/notes/implemented/feature/2026-06-21-subagent-capability-seam.zh.md

@@ -73,4 +73,4 @@ bash seam（[能力 seam](../architecture/2026-06-13-capability-seams.md)）在
 - **递归。** 如果不设限制，进程内子 agent 能看到委派工具并递归调用。进程内后端实现了可选的绝对深度限制和有作用域的实时全局 `toolFilter`；ACP 声明这两项能力为关闭状态，并拒绝此类请求。[subagent 组合控制 Agent Note](2026-07-12-subagent-persona-tool-filter-and-depth.md) 负责定义它们的确切语义和安全边界。
 - **阻塞父轮次。** 前台收集在子 agent 的整个持续时间内保持父 agent 的步骤打开。后台委派使用共享的 `ctx.tasks` 运行时与通用 `task_*` 工具，与后台 bash 共用同一套收集机制；subagent seam 本身仍不感知任务。
 - **实时进度。** 仅暴露生命周期事件与最终结果；逐分片的子→父更新流推迟到后台重新设计时一并处理。
-- **ACP 客户端接口。** 将 ACP 子 agent 的 `fs`/`terminal` 代理回父 agent（共享工作区模式）是后续工作；首版不声明这两项能力，子 agent 在自己的进程中自行服务。
+- **ACP 客户端接口。** 将 ACP 子 agent 的 `fs`/`terminal` 代理回父 agent（共享工作区模式）是后续工作；该后端不声明这两项能力，子 agent 在自己的进程中自行服务。