# ADR 007: TypeScript and Python toolchains

- HTML version: https://robbiepalmer.me/projects/personal-engineering-platform/adrs/007-language-toolchains
- Project: Personal Engineering Platform (https://robbiepalmer.me/projects/personal-engineering-platform.md)
- Status: Accepted
- Date: 2026-09-15
- Initiatives: Semi-autonomous Software Development (https://robbiepalmer.me/initiatives/semi-autonomous-software-development.md)

## Context

The language defaults need to cover the ordinary edit, check, and test loop,
not only runtime schema validation. The repository already repeats one
TypeScript toolchain across the UI, packages, Workers, and evaluation code. Its
Python environments use locked uv projects with Ruff and pytest.

## Decision

For TypeScript, use pnpm for packages and workspaces, Vitest for tests, Biome
for formatting and linting, Husky for repository hooks, Knip for unused code
and dependencies, and CodeQL for semantic security analysis.

For Python, use uv for packages and environments, Ruff for formatting and
linting, and pytest as the test runner. Keep Pydantic and pytest-cases as the
existing validation and reusable-test-case choices.

## Consequences

The language layer now describes a usable development loop. Projects can run
the same locked commands locally and in CI, while mise remains the language
independent entry point.

Some packages need runner-specific integration, such as workerd tests for
Cloudflare Workers or CUDA setup for model tests. Those remain local additions.
The platform selects the default tool, not one universal test environment.

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