Assumer Rules Files

Rules files

Give Assumer project instructions with an Assumer.md rules file. AGENTS.md and CLAUDE.md files are read too, so existing setups keep working.

A rules file tells the agent how your project works: how to build and test it, which conventions to follow and what to avoid. Assumer reads it at the start of every session.

Which files are read

  • Assumer.md in your project (the preferred name)
  • AGENTS.md, the cross-tool standard, if you already have one
  • CLAUDE.md files, so an existing Claude Code setup carries over

A good starting template

# Assumer.md

## Project
Invoice service. Node 22, TypeScript, Fastify, Postgres via Drizzle.

## Commands
- Install: pnpm install
- Test: pnpm test
- Lint: pnpm lint (must pass before you finish)

## Conventions
- Route handlers stay thin; business logic lives in src/services/.
- Never edit generated files in src/gen/.
- Add or update tests for every behaviour change.

Tips

  • Keep it short and specific. Commands and hard rules matter more than prose.
  • Put the commands the agent should run to verify its work near the top.
  • Update the file when the agent repeats a mistake, so it doesn’t happen again.

Read the full guide on the blog: How to write an AGENTS.md rules file that works.

Skills

For longer, reusable instructions, add a skill: a folder with a SKILL.md file. The agent loads a skill only when it is relevant. Browse available skills with /skills.