Nested .alint.yml (monorepo layering)

Opt into per-subtree configs by setting nested_configs: true on the root .alint.yml:

# /.alint.yml (root)
version: 1
nested_configs: true
rules:
  - id: readme-exists
    kind: file_exists
    paths: ["README.md"]
    root_only: true
    level: warning

/packages/frontend/.alint.yml

version: 1
rules:
  - id: frontend-ts-final-newline
    kind: final_newline
    paths: "**/*.ts"
    level: warning

/packages/backend/.alint.yml

version: 1
rules:
  - id: backend-rust-snake-case
    kind: filename_case
    paths: "src/**/*.rs"
    case: snake
    level: error

At load time, alint walks the tree (respecting .gitignore + ignore:), picks up every nested .alint.yml / .alint.yaml, and prefixes each nested rule’s path-like fields (paths, select, primary) with the relative directory the config lives in. So the frontend rule above evaluates as if it were paths: "packages/frontend/**/*.ts" at the root — it fires only on frontend TypeScript files.

Restrictions (MVP)

• Only the root config sets nested_configs: true. Nested configs can’t spawn further nesting.
• Nested configs can only declare version: and rules: — extends:, facts:, vars:, ignore:, respect_gitignore:, and fix_size_limit: are root-only.
• Every rule in a nested config must have a path-like scope field (paths, select, or primary). Rules without any (e.g. no_submodules, which is hardcoded to repo root) can’t be nested.
• Absolute paths and ..-prefixed globs are rejected — they’d escape the subtree the config is supposed to confine.
• Rule-id collisions across configs are rejected with a clear error. Per-subtree overrides aren’t supported yet; if you want to disable a root rule under one subtree, use a when: gate on the root rule for now.

Planned rulesets (v0.5)

• alint://bundled/python@v1 — pyproject.toml, no __pycache__, no committed venv.
• alint://bundled/java@v1 — Maven / Gradle manifest, standard source layout.
• alint://bundled/go@v1 — go.mod, go.sum, no committed vendor/ without the official workflow.
• alint://bundled/compliance/reuse@v1 — FSFE REUSE specification (SPDX headers + LICENSES/).
• alint://bundled/compliance/apache-2@v1 — Apache 2.0 headers + NOTICE file.

Until those ship, you can compose any of them yourself by pairing extends: against an HTTPS URL (with SHA-256 SRI) or a local path.