jim60105 Send Reply Skill
Send your final response to the user. This is the gateway to external communication.
Critical Rules
- One reply only: You can only send ONE reply. You MUST send exactly ONE reply.
- This is the ONLY external output: All other processing remains internal.
- Timeout: The script won't run for more than 30 seconds. If it hangs, do stop_bash.
- No second attempt: If you fail to send the reply or if the script encounters an error, you won't get a second chance to send another reply. That means you failed your job. Make sure your message is final and well-crafted before executing this skill.
- Think before you send: Take a moment to review your message for clarity, tone, and content. Once you hit send, there's no going back.
- Exit directly after sending the reply: After executing this
send-replyskill, you must exit immediately. Do not summarize, continue processing, or attempt to send another message. Your job is done. - Threading: The reply is threaded to the message the file tool (
send-file) most recently delivered, when one exists in this session; otherwise it is threaded to the user's trigger message.
Usage
Two-step flow — the message text MUST NOT appear on the command line.
Write your reply text to a payload file under the session staging directory using your edit/write tool:
$TMPDIR/$SESSION_ID/reply.mdThe
$TMPDIR/$SESSION_IDtokens in that path are expanded by the ACP path boundary, so the write is approved and the text bytes are preserved verbatim (no shell expansion).$TMPDIR/$SESSION_ID/is the per-spawn form of the staging directory; in shared-process deployments the staging directory is shown in your system prompt and the script resolves it automatically.Invoke the script with the payload file path:
${HOME}/.agents/skills/send-reply/scripts/send-reply.ts \ --session-id "$SESSION_ID" \ --message-file "$TMPDIR/$SESSION_ID/reply.md"
WARNING: Never put message content on the command line. The legacy --message "..." / --message=... flags are REMOVED: the shell expands $VAR in them (e.g. $0 → /usr/bin/bash, $HOME, $API_KEY), which corrupts your message and can leak environment variables to the user.
Parameters
| Parameter | Required | Description |
|---|---|---|
--session-id |
Yes | Use the session id rendered in your system prompt. $SESSION_ID works only in per-spawn deployments; in shared-process mode it is not set and the skill library resolves the owning session automatically — a mismatched value is never honored |
--message-file |
Yes | Path of the payload file containing the reply text (must be under $TMPDIR/$SESSION_ID/) |
Error Codes
If the script fails, read the JSON error on stderr. It contains the fix. Common codes:
| Code | Meaning | Fix |
|---|---|---|
SKILL_LEGACY_FLAG |
You used the removed --message flag |
Put the text in $TMPDIR/$SESSION_ID/reply.md and use --message-file |
SKILL_MISSING_PAYLOAD |
No --message-file given |
Write the payload file first, then invoke with --message-file |
SKILL_PAYLOAD_OUT_OF_BOUNDS |
Payload path is outside $TMPDIR/$SESSION_ID/ |
The script only reads its own session's staging dir — stage the text there |
SKILL_PAYLOAD_NOT_FOUND |
Payload file missing/unreadable | Write the file FIRST with the edit/write tool, then invoke the script |
Limits
- Maximum 1 reply per session. After sending the first reply, subsequent calls will be rejected.
- If rejected, use
edit-replyto modify the existing message instead. - Excessive retry attempts will cause the agent process to be terminated.
- Ultrathink carefully and ensure you have all the text prepared before proceeding, as you may not get another chance.