send-file

name	send-file
description	Send one or more files from the workspace to the user on the platform. The files must exist within the workspace directory.
allowed-tools	Bash

Send File Skill

Send one or more files from your workspace to the current conversation channel in a single invocation.

Critical Rules

1. Files must exist: Every file must already exist in your workspace before calling this skill.
2. Workspace boundary: Only files within the workspace or agent-workspace can be sent. Path traversal (../) is not allowed.
3. Size limits: Files exceeding the configured size limit will be rejected. Default per-file limit is 25 MB; default per-invocation batch limit is 50 MB total across all files. At most 10 files can be sent per invocation.
4. Extension restrictions: If an extension whitelist is configured, only matching file types can be sent.
5. One send per session: Only ONE successful send-file call is allowed per session (a multi-file batch counts as one call). Further calls are rejected with HTTP 429, and repeated attempts terminate the agent. If you need to send more, include everything in the single invocation.
6. This skill may be disabled: The administrator may disable this skill. If you receive a "disabled" error, inform the user that file sending is not available.
7. Timeout: The script won't run for more than 30 seconds. If it hangs, do stop_bash.
8. Threading: The file message is sent as a reply to the user's trigger message. A subsequent send-reply in the same session will be threaded to this file message (keeping the conversation in one thread), not to the trigger.

Result

On success the script returns messageId (the delivered message ID), messageIds (all delivered IDs, in send order), filesCount, and nextAction. On partial delivery (Misskey chat) it returns the delivered IDs alongside the error.

Usage

Pass one --file-paths flag per file (repeatable; short alias -f). At least one occurrence is required.

The caption is OPTIONAL. When present, it MUST NOT appear on the command line — use the two-step payload-file flow (same rules as send-reply):

1. (Optional) Write the caption text to a payload file under the session staging directory using your edit/write tool:

   $TMPDIR/$SESSION_ID/caption.md
   

   The $TMPDIR / $SESSION_ID tokens 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.

2. Invoke the script with the payload file path:

   ${HOME}/.agents/skills/send-file/scripts/send-file.ts \
     --session-id "$SESSION_ID" \
     --file-paths "relative/path/to/file.png" \
     --file-paths "relative/path/to/second.pdf" \
     --caption-file "$TMPDIR/$SESSION_ID/caption.md"
   

WARNING: Never put caption text on the command line. The legacy --caption "..." / --caption=... flag is REMOVED: the shell expands $VAR in it, which corrupts the caption and can leak environment variables to the user. The singular --file-path flag is also REMOVED — it is rejected with code SKILL_SINGLE_FILE_FLAG; use the repeatable --file-paths flag instead.

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
--file-paths	Yes	Repeatable file path (relative to the workspace root); one occurrence per file, at least 1
-f	No	Short alias for --file-paths
--caption-file	No	Path of the payload file containing the caption text (must be under $TMPDIR/$SESSION_ID/)

Example

# Send an image
${HOME}/.agents/skills/send-file/scripts/send-file.ts \
  --session-id "$SESSION_ID" \
  --file-paths "output/chart.png"

# Send multiple files in one message
${HOME}/.agents/skills/send-file/scripts/send-file.ts \
  --session-id "$SESSION_ID" \
  --file-paths "exports/report.pdf" \
  --file-paths "exports/chart.png" \
  --file-paths "exports/data.json"

# Send multiple files with a description
${HOME}/.agents/skills/send-file/scripts/send-file.ts \
  --session-id "$SESSION_ID" \
  --file-paths "exports/report.pdf" \
  --file-paths "exports/chart.png" \
  --caption-file "$TMPDIR/$SESSION_ID/caption.md"

Error Codes

If the script fails, read the JSON error on stderr. It contains the fix. Common codes: SKILL_SINGLE_FILE_FLAG (you used the removed singular --file-path flag — use repeatable --file-paths), SKILL_LEGACY_FLAG (you used the removed --caption flag — stage the text in $TMPDIR/$SESSION_ID/caption.md and use --caption-file), SKILL_PAYLOAD_OUT_OF_BOUNDS (payload path outside $TMPDIR/$SESSION_ID/), SKILL_PAYLOAD_NOT_FOUND (payload file not written yet — write it first with the edit/write tool).