loopsmith

Self-evolving agent loops. The gate is code, so "done" cannot be argued.

pip install loopsmith-cli
loopsmith doctor

This distribution is a Rust binary, not a Python library. There is nothing to import. It installs a loopsmith command. To drive loops from Python, use subprocess — its exit codes are its API.

What it is

You describe a purpose in a config — goals, how each is checked, what counts as success, when to stop, what the loop may never do. loopsmith handles scheduling, provider routing, memory, verification, and termination, and can run for weeks without you.

One rule holds the whole design up:

A model must not be the thing that certifies its own completion.

goal_satisfied is written by a deterministic Rust gate and by nothing else, and the gate can revoke: delete a required artifact and a satisfied goal flips back. A system that can only promote is a burndown chart with extra steps.

Five minutes

pip install loopsmith-cli

# --path must be outside any repo you care about: a loop edits files and writes
# state, so it does not get pointed at the tool that runs it.
loopsmith new --path ~/loops/nightly-refactor --purpose "keep the module simple"

cd ~/loops/nightly-refactor
$EDITOR loop.yaml           # your goals, and how each one is checked
loopsmith validate loop.yaml
loopsmith plan     loop.yaml
./run.sh                    # run.cmd on Windows

validate fails on purpose

error  pre_execution: 2 step(s) not marked done: Run this task manually end to
       end at least once; Write down what 'done' means in checkable terms.
       Automating before understanding produces fast, confident garbage

That refusal is the most valuable thing the tool does. Do the task by hand once — the manual run is the spec. Mark each pre_execution step done: true once you actually have.

What a config looks like

Ten sections, A to J: information, the manual work list, goals, validations, success criteria, stop gates, schedules, constraints, execution guidelines, default skills. YAML or Markdown — the same model either way.

name: nightly-refactor
description: keep the payments module simple without breaking it

pre_execution:
  - step: Ran the refactor by hand on one file and kept the diff
    done: true

goals:
  - name: simpler
    description: Cyclomatic complexity down, behaviour unchanged.

validations:
  - target: simpler
    name: tests-still-pass
    mode: objective
    statement: The suite exits clean.
    detector:
      type: script
      command: ./scripts/check-tests.sh
      expect_exit: 0
    blocking: true

success:
  - target: overall
    name: all-blocking-pass
    mode: percentage
    statement: Every blocking validation passes.
    threshold: 1.0

stop_gates:
  max_iterations: 8
  max_revisions_per_node: 3
  max_cost_usd: 5.0
  no_progress_iterations: 3

graph:
  nodes:
    - id: refactor
      role: builder
      instruction: Simplify one function. State any assumption you had to make.
      goals: [simpler]
      isolated: true          # its own git worktree
    - id: review
      role: judge
      instruction: Check the diff against the brief. Pass or fail per check, with evidence.
      depends_on: [refactor]
      goals: [simpler]
      tier: strong

Detectors are file_exists, regex, script, and composites. Only a detector can satisfy a goal — a model's opinion of its own work never does.

While it runs

The loop never edits its own config. Changes to goals, validations, success criteria, and sub-agent adoption are written as proposals for a human to apply.

Providers and BYOK

Every provider is a command template, which is what makes bring-your-own-key free: Claude Code, Ollama, a Grok CLI, an OpenAI-compatible endpoint driven by curl, an MCP server over stdio — all of them are "a program you run with a prompt". Adding one is a config edit, never a rebuild.

requires_env names variables that must exist. loopsmith never reads their values, so a key cannot reach a prompt, a log, or the ledger.

⚠ Never paste an API key into a chat window, a config file, or an issue. If one ends up somewhere it should not be, rotate it — deleting the message is not enough.

How this distribution installs the binary

The binary is fetched on first run, not during pip install, and cached under ~/.loopsmith/bin/<version>/ (override with LOOPSMITH_HOME).

That is deliberate. A wheel that downloads at install time breaks in every environment that installs without a network and runs with one — CI images, Docker build stages, locked-down build hosts — and the failure surfaces as an install error for a package the user has not tried to use yet.

Every download is verified against the release's published SHA256SUMS before it is executed. Fetching a binary and running it unverified is a supply-chain hole with a progress bar.

Prebuilt for:

Anywhere else, build from source — it is the same program:

cargo install loopsmith

The distribution name

loopsmith on PyPI was already registered by an unrelated project, so this distribution is loopsmith-cli. The installed command is loopsmith either way. Elsewhere: loopsmith on crates.io, @bitphill/loopsmith on npm, and the bitphill/loopsmith Homebrew tap.

Documentation

• Full README
• Section-by-section config reference
• Architecture and the reasoning behind it
• Thirteen worked examples
• Changelog

MIT licensed. © bitphill