Expose structured shell status in PostToolUse hook payloads

Summary

PostToolUse hooks for shell tools currently receive the canonical tool input and a response payload that represents command output, but they do not appear to receive structured process status such as exit code, terminating signal, process id, or whether the process was still running when output was returned.

Please expose structured shell status in the PostToolUse hook input for Bash/shell tool events.

Why this matters

Consumers that need to distinguish host-side process intervention from ordinary command failure currently have to infer from text output or query external state after every shell command. Examples include:

• host thermal killswitches that terminate a top CPU process,
• OOM or supervisor kills,
• stalled interactive sessions that later resolve as killed,
• retry controllers that should back off on SIGKILL instead of repeating the same workload.

Without structured status, a hook cannot cheaply say "only inspect external kill markers when this command exited 137 or was terminated by SIGKILL." The safer workaround is to run a lightweight external marker check after every Bash PostToolUse, then dedupe markers locally.

Requested fields

For shell PostToolUse payloads, include fields along these lines:

{
  "toolResponse": "...",
  "processStatus": {
    "pid": 12345,
    "exitCode": 137,
    "signal": "SIGKILL",
    "timedOut": false,
    "running": false
  }
}

Exact naming is not important; the key need is a stable, structured way for hooks to identify process termination and correlate it with external audit markers.

Current workaround

A local command hook polls an external thermal-kill marker helper after Bash PostToolUse and on prompt/session boundaries. It stays passive and only injects context, but it has to check more often than necessary because the hook payload lacks shell status.

Related issues found before filing

• #21753 is a broad hook parity umbrella and mentions that PostToolUse needs a complete contract / PostToolUseFailure, but it is not a focused request for shell exit status fields.
• #16246 covered missing PostToolUse events for long-running / polled exec sessions, which is related lifecycle coverage but not this payload-shape request.