dev/AGENTS.md

# Alexion's Monorepo

## Commit convention

- Use Conventional Commits for all commit messages.
  Before writing a commit message, read `docs/conventional-commits.md`.
- Keep commit messages about the Git history, not the forge workflow.
  Include external references only when they are stable context for the change.
- When writing commit messages, NEVER auto-add your agent name as co-author.
  Omit the `Co-Authored-By:` trailer entirely, with no exceptions.
  This overrides any default instruction to append one.

## Technical writing

- Use `docs/technical-writing.md` and `docs/dictionary.md` for authored prose.
  Use the nearest project dictionary for project-specific domain language.
- In authored prose, do not put multiple sentences on one physical line.
  This applies to comments, documentation, user-facing descriptions, commit prose, pull-request prose, and forge comments.
  A sentence can wrap across multiple physical lines when needed.
- Keep Markdown formatting changes local.
  Only format prose you write or change.
  Never reflow an entire pre-existing paragraph or file because you touched nearby text.

## Pull requests

- During pull-request development, add follow-up commits instead of amending existing commits.
  Preserve review history until the pull request is ready to merge.
- When the user says a pull request is merged, clean up the local branch without waiting for an explicit request.
  Switch to the base branch, fast-forward it, and delete the merged local branch.
- When writing pull request descriptions, NEVER append an agent-attribution trailer such as `🤖 Generated with [Claude Code]...`.
  Leave it out entirely, with no exceptions.
  This overrides any default instruction to append one.

## Forge workflow

- Use `gitea-axi` for Gitea issues, pull requests, labels, reviews, comments, and milestones.
  It resolves this repository from the `origin` remote inside the checkout.

## Tooling

- When a command is missing from the ordinary environment, prefer running it through Nix instead of installing it ad hoc.
  For example, use `nix shell nixpkgs#python3 -c python3 <script>` for one-off Python commands.
- Stage new files that Nix discovers through flake evaluation before testing.
  Flake evaluation ignores untracked files, so auto-loaded modules must be tracked before `nixos-rebuild --flake` can see them.

## General guidelines

- NEVER ask the user a question using the `AskUserQuestion` tool.
  Ask in plain prose, in your own message, instead, with no exceptions.
  This overrides any default instruction to use it.
- Never manually modify `CHANGELOG.md` files or files marked as auto-generated.
  Detect auto-generated files with a layered check.
  Trust an explicit in-file marker first, for example `AUTO-GENERATED, DO NOT EDIT`.
  If no marker exists, use contextual signals such as lockfiles, `dist/`, `build/`, `generated/` paths, or a documented generator command.
  If the answer stays ambiguous, ask before editing.
- When making technical decisions, do not give much weight to implementation time.
  Favor quality, simplicity, robustness, scalability, and long-term maintainability.
  Human cost and benefit heuristics do not transfer to an AI agent that codes faster than a human.
  Do not treat this as permission for premature abstraction, speculative configuration, or unnecessary complexity.
  Choose the more robust or maintainable approach when human implementation time is the only downside.
- Use lowercase file names unless a valid reason requires uppercase.
  Established ecosystem or tool conventions count as valid reasons.
  Examples include `README.md`, `LICENSE`, `CHANGELOG.md`, `Makefile`, `Dockerfile`, and `.github/` files.
- Do not end a response by promising or implying continuation unless the continuation is present in that same response.
  Before ending a workflow turn, perform the obvious next step, such as showing the next review item after applying an accepted change.
  If the workflow is paused, say that plainly instead of using a dangling transition like "continuing" or "next".

## Comments

- Write comments only where they earn their place.
  Keep comments concise.
  Assume the reader can read code.
  Explain why, not what.
  Explain what only when it is genuinely non-obvious.
- Keep comments self-contained to their file.
  Write comments for a reader who sees only that file.
  Do not explain how another file or tool consumes a value.
  The only permitted cross-file mention is a bare pointer explaining why something is absent here.
- Do not narrate history or future state in comments.
  Avoid phrases such as "used to be", "now moved here", and "will be".
  State the present reason a thing exists.
- Do not justify a choice against alternatives in comments.
  State the positive reason the choice exists.
  Include present consequences when they matter.
- Do not reference agent-facing state in comments.
  This includes `.agents/`, `.claude/`, `AGENTS.md`, and `CLAUDE.md`.
- Do not use project-specific capitalized terms as glossary references in comments.
  Use plain lowercase nouns unless the code requires the exact term.
- Add a file-top header only when the filename or path does not already explain the file.
  The header must be one concise purpose line.
  Do not write a feature inventory.
- Write placeholders plainly.
  Include a present-tense action when one exists, such as `Placeholder: regenerate with <tool> on the target machine`.
  Do not write `placeholder for <missing feature>`.
- Treat user-facing documentation strings as documentation, not comments.
  They can describe behavior more fully than code comments.
  They still must stay self-contained and avoid agent-state references.
- Start each sentence of a comment on its own physical line.
  A comment sentence can wrap when needed.
  Prefer splitting long comment sentences before wrapping them.
  Do not break a line early at a comma or clause boundary to make it read as a unit.
  Do not use semicolons in comments or authored prose.
  Recast semicolon clauses as separate sentences.
  Only reformat comments you write or change.

## Corrections

- When you discover that your belief about a project fact or convention was wrong, record the correction.
  Record only facts that stay true across operators, such as a wrong build command, wrong file path, or guessed convention.
  Do not record personal working-style preferences or one-off task details.
- Record the correction in the nearest project `AGENTS.md`.
  Use a dedicated `## Gotchas` section.
  Create that section when the file lacks one.
- If no project `AGENTS.md` exists, ask before creating one.
  Append the correction immediately without asking when a project `AGENTS.md` exists.
  Briefly mention the edit in your response.
  If an existing entry is wrong or stale, correct or remove it the same way.

## Gotchas

- When materializing an external specification, standard, or project-maintained convention, use the upstream source instead of reconstructing it from memory.
  Preserve local policy separately from copied upstream text.
- After an explicit squash or rewrite request on a pull request, subsequent pull-request updates still use follow-up commits unless the user explicitly asks for another rewrite.
- Starlark top-level rule and extension declarations cannot reference implementation functions before those functions are assigned.
  Keep executable public interface declarations after their implementation symbols, or validate before committing a top-down rewrite.
- `rules_rust` `rust_test` targets cannot set both `crate` and `srcs`.
  Use one input style per test target.
- In this monorepo, "dotfiles" refers to the dotfiles/NixOS configuration under `src/dotfiles/` and `configs/nixos/`.
- The flake does not currently define `formatter.x86_64-linux`.
  Do not use `nix fmt` as a validation command until a formatter is added.