easa-erules

Universal, deterministic toolkit for EASA Easy Access Rules / eRules XML publications.

This is not “XML → Markdown only”. It is a local CLI for humans and LLM agents:

• fetch a regulation (or a pinned version) from EASA,
• load Flat OPC / OOXML packages,
• parse into a canonical Regulation AST,
• export Markdown, JSON, and HTML,
• extract single rules, search with SQLite FTS5, explore cross-references,
• validate conversions without silently dropping content.

Regulatory text is never rewritten by an LLM during conversion. Conversion is deterministic; models should reason on tool output.

Project status

Verdict: MVP complete for agent-local EAR workflows, with designation/metadata polish and docs in place. Next expansion is optional (more live packages, FAA/ASTM when needed).

Install

Requires Python ≥ 3.11.

# PyPI (recommended for users)
pip install easa-erules

# or with uv
uv pip install easa-erules

From source / development:

git clone https://github.com/mrSpringpeace/easa-erules.git
cd easa-erules
uv venv && source .venv/bin/activate
uv pip install -e ".[dev]"
# or: pip install -e ".[dev]"

Pinned git tag (if PyPI is unavailable):

pip install "git+https://github.com/mrSpringpeace/easa-erules.git@v0.1.2"

Entry point: easa-erules.

Disclaimer: Unofficial toolkit. Always verify critical interpretations against the official EASA Easy Access Rules publication. This software does not re-license regulatory text.

Quick start

# Catalog
easa-erules list
easa-erules info vla

# Download latest XML into the cache
easa-erules fetch cs-vla
easa-erules fetch cs-vla --version "Amendment 1"

# Inspect / convert / extract / search / refs
easa-erules inspect cs-vla
easa-erules convert cs-vla -o ./out --split
easa-erules convert ./local.xml -o ./out --format html
easa-erules extract cs-vla CS-VLA.303 --format json
easa-erules query cs-vla "factor of safety" --json
easa-erules refs cs-vla CS-VLA.303 --json
easa-erules validate ./out

Local path or registry id/alias is accepted for most commands. Use --fetch on convert/extract/query when the id is not cached yet.

Cache layout

~/.cache/easa-erules/          # override: EASA_ERULES_CACHE
  cs-vla/
    source.xml                 # latest convenience copy
    meta.yaml
    search.sqlite              # FTS index (built on first query)
    versions/<slug>/
      source.xml
      meta.yaml                # sha256, download_url, retrieved_at, …
      original.zip

Split convert output

out/
├── index.md
├── metadata.yaml
├── document.json
├── conversion-report.json
├── rules/
│   └── cs-vla-303.md
└── assets/
    └── cs-vla-303-fig-01.png

CLI reference

Architecture

EASA landing page ──fetch──► cache (XML + meta)
                              │
Local XML/DOCX ───────────────┤
                              ▼
                     OpcPackage (Flat OPC / ZIP)
                              ▼
                     EasaDocumentParser
                              ▼
                     Regulation AST ──normalize──►
                              ▼
              ┌───────────────┼───────────────┐
              ▼               ▼               ▼
          Markdown          JSON            HTML
              │
              ├── SQLite FTS5 (query)
              ├── Reference graph (refs)
              └── Validation / conversion-report.json

Built-in sources

Defined in src/easa_erules/sources/easa.yaml (stable landing pages, not fragile direct URLs):

cs-vla, cs-lsa, cs-22, cs-23, cs-25, cs-27, cs-29, cs-e, cs-p, cs-etso, part-21, uas-rules

For LLM agents

Use the thin skills under skills/ (generic / Codex / Claude Code / OpenCode).

Cookbook: examples/agent-cookbook.md
Full manual: docs/MANUAL.md

Rules of engagement:

1. Prefer query / extract / refs with --json over stuffing full regulations into context.
2. Never hand-write or “fix” regulatory text from model memory.
3. After bulk convert, run validate.
4. Ground answers only on tool output.

Development

pytest
# real EAR smokes (checked-in samples):
pytest tests/test_real_samples.py -v
# optional live network re-fetch:
EASA_ERULES_LIVE=1 pytest tests/test_real_samples.py -v

ruff check src tests

• Unit fixtures: tests/fixtures/
• Golden renders: tests/golden/
• Real documents: tests/real_samples/ (see README there)

Design principles

• Deterministic conversion — same source + parser version → same AST/ids/exports
• No silent content loss — unknown elements and failed structures are reported
• AST in the middle — no direct XML → Markdown hacks
• Agent-first CLI — stable JSON shapes for extract/query/refs

License

MIT