background-callback

A callback tool that lets a running task send a message back into the coding agent's input.

In plain words
What is it for?
Use it for multi-step workflows, progress updates from scripts, and tasks that need the agent to continue after an external process responds.
Why use it?
It lets long or background tasks notify the agent when they reach a checkpoint or finish.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/shanjiaming/send-to-claude-plugin/background-callback
Any agent
npx skills add shanjiaming/send-to-claude-plugin --skill background-callback
Clone the repo
git clone --depth 1 https://github.com/shanjiaming/send-to-claude-plugin

Made for: Claude Code, Codex.

Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,078 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00024 $0.01078
Opus 5 $0.00012 $0.00539
Sonnet 5 $0.00005 $0.00216
Haiku 4.5 $0.00002 $0.00108

Measured 2d ago against content hash 971794ee1e87, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

background-callback scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

os.system(f'send-to-claude "{msg}"')
skills/background-callback/SKILL.md · 177 lines

How it starts

The opening of the file, as written. The whole thing — 177 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Background Callback Skill

IMPORTANT: You (Claude) can now send messages to your own terminal input.

The send-to-claude command lets you write text into your own terminal session, enabling:

  • Autonomous multi-step workflows (start task → get callback → continue automatically)
  • Progress reports from long-running scripts
  • Self-triggered actions

Core Capability

You can execute:

send-to-claude "Your message here"

And that message will appear in your input as if the user typed it, waking you up to continue working.

Key mechanism: When you create scripts (Python/Bash/etc), they inherit your terminal's environment variables ($TMUX or $ITERM_SESSION_ID). This means:

  1. You write a script with send-to-claude calls embedded
  2. The script runs (possibly in background)
  3. When script calls send-to-claude, it finds YOUR session via inherited environment variables
  4. Message gets sent back to YOUR input
  5. You wake up and continue working

This enables true autonomous workflows where external programs can call back into you.

When to Use

Use send-to-claude when the user requests:

  1. Background tasks with notifications

    • "Run this and let me know when it's done"
    • "Start training in the background and notify me"
    • "Execute this script and tell me the result"
  2. Progress reports

    • "Report progress during training"
    • "Let me know every 10 epochs"
    • "Update me on the status"
  3. Long-running tasks

    • Tasks that take >30 seconds
    • Multi-step workflows
    • Experiments or training runs

How to Use

In Python Scripts

When creating Python scripts, embed send-to-claude at key points:

import os

def callback(msg):
    os.system(f'send-to-claude "{msg}"')

# Start notification
callback("Starting training...")

# Progress updates
for epoch in range(100):
    train()
    if epoch % 10 == 0:
        callback(f"Progress: {epoch}/100 epochs")

# Completion
callback("Training complete! Check results.")

Read the full file on GitHub · 177 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 177 lines · 24 tokens per session scan A 971794ee1e87

Subscribe to this mod's changes

background-callback is a skill published in the GitHub repository shanjiaming/send-to-claude-plugin (5 stars, last pushed 7mo ago), licensed MIT. It adds 24 tokens to every session and 1,078 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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