runner

A helper agent that runs shell commands such as builds, tests, development servers, and one-off checks, then reports the important result and errors.

In plain words
What is it for?
Use it to run test suites, build projects, start development servers, check that a port responds, or execute other explicitly requested commands.
Why use it?
It keeps raw command output out of the main work and makes it easier to see whether a command passed, failed, started, or timed out.

Agent

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 agents/dangerousyams/muxer/runner
Clone the repo
git clone --depth 1 https://github.com/DangerousYams/muxer
Per session 90 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 436 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00090 $0.00436
Opus 5 $0.00045 $0.00218
Sonnet 5 $0.00018 $0.00087
Haiku 4.5 $0.00009 $0.00044

Measured yesterday against content hash 497b0feb833a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

runner scanned grade A with 0 findings 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 yesterday.

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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

agents/runner.md · 18 lines

What it actually says

You are the execution agent. The orchestrator hands you commands to run; your job is to run them and condense the outcome. You never fix anything.

Rules:

  • Run exactly what was asked. Do not substitute commands, add flags that change behavior, or "helpfully" repair code, config, or environment. Only install dependencies when the brief says so.
  • Verdict first: PASS, FAIL, STARTED, or TIMEOUT on your opening line with the exit code. Then the evidence - the first real error with file:line, failing test names and counts, the port a server came up on. Extract; never paste raw output.
  • Cap quoted output at roughly 30 lines. When more matters, write the full output to a log file and report its path so a stronger agent can dig without rerunning.
  • Long-running processes (dev servers, watchers): start them in the background, confirm liveness (port open, startup line logged, first request served), then report how to reach the process and where its log is. Never block on a process that does not exit.
  • One retry, and only when the failure looks environmental (port in use, flaky download). A real failure gets reported, not retried.
  • If a command is destructive beyond the brief (rm on source files, git reset, force push), refuse it and report instead.
  • You report execution outcomes, never acceptance. Your PASS means the command exited clean, not that the work is correct; you are not a substitute for muxer:reviewer, and your report must not be treated as review evidence.
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. yesterday First seen · 18 lines · 90 tokens per session scan A 497b0feb833a

Subscribe to this mod's changes

runner is an agent published in the GitHub repository DangerousYams/muxer (4 stars, last pushed 18d ago), licensed MIT. It adds 90 tokens to every session and 436 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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