fix(agents): prefer background completion wake over polling (#60877)

* fix(agents): prefer completion wake over polling

* fix(changelog): note completion wake guidance

* fix(agents): qualify quiet exec completion wake

* fix(agents): qualify disabled exec completion wake

* fix(agents): split process polling from control actions

src/agents/bash-tools.process.ts

@@ -120,6 +120,7 @@ function resetPollRetrySuggestion(sessionId: string): void {
 export function describeProcessTool(params?: { hasCronTool?: boolean }): string {
   return [
     "Manage running exec sessions for commands already started: list, poll, log, write, send-keys, submit, paste, kill.",
+    "Use poll/log when you need status, logs, quiet-success confirmation, or completion confirmation when automatic completion wake is unavailable. Use write/send-keys/submit/paste/kill for input or intervention.",
     params?.hasCronTool
       ? "Do not use process polling to emulate timers or reminders; use cron for scheduled follow-ups."
       : undefined,