Skill: lang

Load trigger: "load lang skill" > DORA: AI Capabilities 3, 4 Token cost: Low

Purpose

Language-specific toolchain conventions for Python and TypeScript. CI gate commands, file layout, interface patterns, and configuration standards. Implements DORA AI Capabilities 3, 4.

When to Use

• Working on a Python or TypeScript/JavaScript project
• Setting up CI gates for language-specific tooling

Sub-skills (now integrated)

PYTHON

Skill: Language — Python

Load trigger: "load lang-python skill" > Stack: Python 3.11+, ruff, mypy, pytest, pytest-cov, uv or pip Token cost: Low

Toolchain Reference

File Layout Convention

src/
  [package_name]/
    __init__.py
    services/           ← business logic
    utils/              ← pure functions
    models/             ← data models (Pydantic or dataclasses)
    api/                ← HTTP handlers / FastAPI routers
tests/
  test_services/        ← mirrors src/services/
  test_utils/           ← mirrors src/utils/
  conftest.py           ← shared fixtures
pyproject.toml          ← all tool config here (not setup.py)

CI Gate Commands (ci-quality.yml)

- name: Set up Python
  uses: actions/setup-python@v5
  with:
    python-version: "3.11"

- name: Install dependencies
  run: pip install -e ".[dev]"

- name: Lint
  run: ruff check .

- name: Typecheck
  run: mypy src/

- name: Test with coverage
  run: pytest --cov=src --cov-fail-under=80 --cov-report=xml

Type Standards

• All public function signatures fully annotated
• Use from __future__ import annotations for forward references
• Prefer TypeAlias over bare assignments for complex types
• Pydantic v2 for data validation at service boundaries
• No # type: ignore without an inline comment explaining why

pyproject.toml Minimum Config

[tool.ruff]
line-length = 88
target-version = "py311"

[tool.ruff.lint]
select = ["E", "F", "I", "UP", "B"]

[tool.mypy]
strict = true
python_version = "3.11"

[tool.pytest.ini_options]
testpaths = ["tests"]
addopts = "--strict-markers"

[tool.coverage.run]
source = ["src"]
omit = ["tests/*"]

OTEL SDK (for obs-agent)

pip install opentelemetry-sdk opentelemetry-exporter-otlp-proto-http

Init pattern: call configure_otel() at application entry point before importing service modules. Read OTEL_SERVICE_NAME and OTEL_EXPORTER_OTLP_ENDPOINT from env.

TYPESCRIPT

Skill: Language — TypeScript

Load trigger: "load lang-typescript skill" > Stack: TypeScript, Node.js, ESLint, tsc, Jest/Vitest, npm Token cost: Low

Toolchain Reference

File Layout Convention

src/
  types/index.ts        ← all shared types and interfaces
  services/             ← business logic, no UI dependencies
  utils/                ← pure functions, no side effects
  screens/ or pages/    ← UI layer only
tests/
  services/             ← mirrors src/services/
  utils/                ← mirrors src/utils/

CI Gate Commands (ci-quality.yml)

- name: Lint
  run: npm ci && npm run lint

- name: Typecheck
  run: npm run typecheck

- name: Test with coverage
  run: npm run test:coverage
  env:
    CI: true

- name: Coverage threshold
  run: |
    COVERAGE=$(cat coverage/coverage-summary.json | jq '.total.lines.pct')
    if (( $(echo "$COVERAGE < 80" | bc -l) )); then
      echo "Coverage $COVERAGE% is below 80% threshold"
      exit 1
    fi

Type Standards

• No any in service or utility functions
• Catch blocks: catch (error: unknown) — narrow before use
• All external API responses typed with Zod or explicit interface
• No inline type definitions in function signatures — define in src/types/index.ts

OTEL SDK (for obs-agent)

npm install @opentelemetry/sdk-node @opentelemetry/exporter-trace-otlp-http

Init pattern: src/instrumentation.ts — imported before all other imports in entry point.

Node Version

Node 22 LTS. Pin in .nvmrc and engines field in package.json. GitHub Actions: uses: actions/setup-node@v4 with node-version: '22'.