diff --git a/.agents/notes/implemented/feature/2026-07-16-persistent-pty-sessions.i18n.yaml b/.agents/notes/implemented/feature/2026-07-16-persistent-pty-sessions.i18n.yaml
index 4c73d590af..34e6c14df6 100644
--- a/.agents/notes/implemented/feature/2026-07-16-persistent-pty-sessions.i18n.yaml
+++ b/.agents/notes/implemented/feature/2026-07-16-persistent-pty-sessions.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/2026-07-16-persistent-pty-sessions.md
-2026-07-16-persistent-pty-sessions.md: 43c87bb159cfe1ab9f8d3a80c2adf25a57ae6e3b
-2026-07-16-persistent-pty-sessions.zh.md: 8afc2103447cc58b1fcbc1062b9564e8ed643477
+2026-07-16-persistent-pty-sessions.md: 4fff1742721fa13ea11f1b8ec833e5e5b7e68df8
+2026-07-16-persistent-pty-sessions.zh.md: 88e7a0bc4b8af21dc51b6a654a1c9f93760b3e81
diff --git a/.agents/notes/implemented/feature/2026-07-16-persistent-pty-sessions.md b/.agents/notes/implemented/feature/2026-07-16-persistent-pty-sessions.md
index 43c87bb159..4fff174272 100644
--- a/.agents/notes/implemented/feature/2026-07-16-persistent-pty-sessions.md
+++ b/.agents/notes/implemented/feature/2026-07-16-persistent-pty-sessions.md
@@ -80,6 +80,8 @@ On macOS there is no exact syscall tier. Output silence returns `inferred_idle`
 
 Tier 2 returns `inferred_idle` after `idleSilenceMs` without output. A sleeping or network-blocked command can therefore look ready. Tier 3 returns `timeout` after `timeoutMs` so a foreground tool call cannot hold the agent indefinitely. The result preserves the distinction; callers may wait through `ctx.tasks`, signal the foreground group, or inspect from another session.
 
+Once a send settles under any tier, `PtySendOperation.append` stops accepting output, so later child output no longer reaches that settled operation; it still reaches the scrollback, and any send that is active when it arrives. A test that waits for a marker on the operation it started must therefore set `idleSilenceMs` and `timeoutMs` above the child's own startup latency; interpreter startup on a loaded macOS runner otherwise ends the send before the marker is printed.
+
 `node-pty` data notifications feed one terminal parser. Parser carry state handles control sequences and a trailing carriage return split across callbacks, so a divided CRLF produces one newline rather than a pagination-changing blank line. The implementation normalizes line-oriented output, but it does not promise correct interaction with a full-screen application.
 
 ### Model-visible output and durability
diff --git a/.agents/notes/implemented/feature/2026-07-16-persistent-pty-sessions.zh.md b/.agents/notes/implemented/feature/2026-07-16-persistent-pty-sessions.zh.md
index 8afc210344..88e7a0bc4b 100644
--- a/.agents/notes/implemented/feature/2026-07-16-persistent-pty-sessions.zh.md
+++ b/.agents/notes/implemented/feature/2026-07-16-persistent-pty-sessions.zh.md
@@ -80,6 +80,8 @@ macOS 没有精确 syscall 层。任何前台进程组输出静默都会返回 `
 
 Tier 2 在持续 `idleSilenceMs` 没有输出后返回 `inferred_idle`，因此 sleep 或网络阻塞的命令可能看似 ready。Tier 3 在 `timeoutMs` 后返回 `timeout`，避免前台工具调用无限占住 agent。结果保留这些区别；调用方可以通过 `ctx.tasks` 等待、向前台组发信号，或从另一个会话排查。
 
+一次 send 在任一层级 settle 之后，`PtySendOperation.append` 就不再接受输出，此后子进程的输出不会再进入那个已 settle 的 operation；它仍然会进入 scrollback，以及此时恰好处于活跃状态的任何 send。因此，等待自己所启动的 operation 上出现标记的测试，必须把 `idleSilenceMs` 与 `timeoutMs` 设得高于子进程自身的启动耗时；否则在负载较高的 macOS runner 上，解释器启动会在标记打印之前就结束这次 send。
+
 `node-pty` data 通知进入同一个终端 parser。parser 的 carry state 会处理跨 callback 的控制序列和位于 callback 末尾的回车；因此，即使 CRLF 被拆开，也只会生成一个换行，而不会产生改变分页的空行。实现会规范化行式输出，但不承诺正确操作全屏应用。
 
 ### 模型可见输出与持久性
diff --git a/packages/pty/pty-local/tests/local.spec.ts b/packages/pty/pty-local/tests/local.spec.ts
index 8c1c58f319..f3ed6675e7 100644
--- a/packages/pty/pty-local/tests/local.spec.ts
+++ b/packages/pty/pty-local/tests/local.spec.ts
@@ -66,6 +66,10 @@ async function harness(
   return { ctx, root, agent, fiber, sandbox: ctx.sandbox as PassthroughSandbox }
 }
 
+// PtySendOperation.append drops output once the operation settles, so this only
+// observes a marker the child prints while `operation` is still active. A caller
+// whose child is slow to print must raise the harness `timing` bounds too;
+// extending this deadline alone cannot recover output the operation never collected.
 async function waitForOutput(operation: PtySendOperation, expected: string, timeoutMs = 2_000): Promise<void> {
   const deadline = Date.now() + timeoutMs
   let output = ''