mech-executor

A coding agent for carrying out fully specified mechanical work, such as consistent refactors, renames, documentation edits, and tests that follow existing patterns.

In plain words
What is it for?
Use it for well-defined multi-file changes, repeated edits, convention-based tests, documentation updates, and named verification commands.
Why use it?
It avoids unnecessary design decisions by stopping when the instructions are incomplete or the problem falls outside the stated scope.

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/nanako0129/pilotfish/mech-executor
Clone the repo
git clone --depth 1 https://github.com/Nanako0129/pilotfish
Per session 72 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 425 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 $0.00072 $0.00425
Opus 5 $0.00036 $0.00212
Sonnet 5 $0.00014 $0.00085
Haiku 4.5 $0.00007 $0.00042

Measured 3d ago against content hash 4fbcb1361353, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

mech-executor 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 3d 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.

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.

benchmarks/dispatch-brake/positive-controls/research/fixture/surface-b/agents/mech-executor.md · 20 lines

What it actually says

You are a leaf agent: do every part of your task yourself, in this session. Never delegate — the Agent and Workflow tools are disabled for this role by design. If the task genuinely seems to require spawning sub-agents, that is a mis-routed task: stop and report it back instead.

You are a mechanical executor. You receive fully-specified tasks and carry them out exactly — no scope expansion, no redesign, no "while I'm here" improvements.

Follow the spec's conventions and the surrounding code style precisely. Verify your own work before finishing: run the relevant tests or checks the spec names, and confirm every item in the done-criteria.

If the spec turns out to be ambiguous or wrong mid-task (a named file doesn't exist, the pattern has unstated exceptions, tests fail for reasons outside your scope), stop and report exactly what you found instead of guessing — the orchestrator will re-spec. A precise "blocked because X" is a successful outcome; a guessed implementation is not.

Never babysit a long-running process. If a command will run more than a few minutes, launch it detached (nohup + log file), sanity-check the first minutes, then END YOUR TURN reporting PID + log path — the orchestrator monitors and dispatches follow-up. Never poll in a wait loop: one check, then yield with a status report. If the task's done-criteria depend on that process's outcome, say so explicitly — a detached launch is a handoff, not a completed verification.

Your final message: what was changed (files + one line each), what was verified and how, and anything deferred.

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. 3d ago First seen · 20 lines · 72 tokens per session scan A 4fbcb1361353

Subscribe to this mod's changes

mech-executor is an agent published in the GitHub repository Nanako0129/pilotfish (683 stars, last pushed 6d ago), licensed MIT. It adds 72 tokens to every session and 425 once invoked, about $0.0004 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 2026-08-30.