Code Style and Tooling

Biome (Formatting + Linting)

Biome is the primary tool for both formatting and linting. There is no Prettier.

Configuration lives in biome.json at the repo root.

Formatting

Setting	Value
Line width	120
Indent style	Spaces
Indent width	2

Run the formatter:

pnpm format  # biome check --write .
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Linting

Biome's recommended rules are enabled. Notable additions:

Rule	Level	Purpose
noUndeclaredEnvVars (nursery)	warn	Encourages documenting env variable usage
noRestrictedImports (apps/web)	error	Prevents importing @repo/db directly in the web app

Test File Overrides

Test files (*.test.ts, *.test.tsx) have relaxed rules:

• noExplicitAny: off
• noNonNullAssertion: off

This allows pragmatic test code without fighting the linter.

Import Organization

Biome automatically organizes imports into groups separated by blank lines:

// 1. Node builtins, third-party packages (excluding @repo)
import { z } from "zod";
import { TRPCError } from "@trpc/server";

// 2. Internal @repo/* packages
import { patientsRepo } from "@repo/db";
import { authenticatedProcedure } from "@repo/trpc/procedures";

// 3. App-level aliases (~/)
import { Providers } from "~/lib/providers";

// 4. Relative imports
import { PatientForm } from "./components/PatientForm";
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The groups are configured in biome.json:

{
  "assist": {
    "actions": {
      "source": {
        "organizeImports": {
          "level": "on",
          "options": {
            "groups": [
              [
                ":NODE:",
                ":PACKAGE:",
                ":PACKAGE_WITH_PROTOCOL:",
                ":URL:",
                "!@repo/**"
              ],
              ":BLANK_LINE:",
              "@repo/**",
              ":BLANK_LINE:",
              "~/**",
              ":PATH:"
            ]
          }
        }
      }
    }
  }
}
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Test files have their own import order: mocks first, then vitest/test utilities, then everything else.

ESLint

ESLint is used only for Next.js-specific rules in apps/web. The config is in apps/web/eslint.config.mjs and uses @next/eslint-plugin-next (recommended + core-web-vitals).

The lint script in apps/web runs both Biome and ESLint:

{
  "lint": "biome check . && next lint"
}
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TypeScript

Strict Mode

All packages use TypeScript strict mode. The shared configs live in packages/typescript-config/:

Config	Used By	Key Settings
base.json	Most packages	strict: true, target: ES2022, module: NodeNext, noUncheckedIndexedAccess: true
nextjs.json	apps/web	Extends base; module: ESNext, moduleResolution: Bundler, jsx: preserve
react-library.json	React packages	Extends base with React/JSX support

Key Compiler Options

• strict: true: All strict checks enabled.
• noUncheckedIndexedAccess: true: Array/object index access returns T | undefined.
• isolatedModules: true: Ensures compatibility with transpilers.
• declaration: true + declarationMap: true: Generates .d.ts files for package consumers.

Type Checking

pnpm check-types  # Runs tsc --noEmit across all packages via Turbo
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Turborepo

Task definitions live in turbo.json:

Task	Dependencies	Cached	Notes
build	^build	Yes	Outputs: .next/**; env vars included in cache key
dev	--	No	Persistent task
test	^build	Yes	Inputs: **/*.test.{ts,tsx}, .env*
test:watch	--	No	Persistent task
lint	^lint	Yes
check-types	^check-types	Yes
storybook:build	^build	Yes	Outputs: storybook-static/**

Cache Keys

Build and test cache keys include environment variables to ensure rebuilds when config changes:

• BASE_URL, SUPABASE_URL, SUPABASE_ANON_KEY, DATABASE_URL
• NEXT_PUBLIC_TRPC_URL, NEXT_PUBLIC_OAUTH_REDIRECT_URL
• And more (see turbo.json env arrays).

pnpm

Workspace Layout

Defined in pnpm-workspace.yaml:

packages:
  - "apps/*"
  - "packages/*"
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Overrides

The root package.json pins zod to 4.3.6 across the workspace:

{
  "pnpm": {
    "overrides": {
      "zod": "4.3.6"
    }
  }
}
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Engine Requirements

{
  "engines": {
    "node": ">=20"
  },
  "packageManager": "pnpm@10.23.0"
}
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Next: Testing