Create packages/<package-name>/.
Add:
- package.json
- tsconfig.json
- tsconfig.build.json
- CHANGELOG.md
- README.md
- LICENSE
- src/
For new packages, start CHANGELOG.md with ## Unreleased as the first section to indicate changes are not released yet.

Set up package.json using monorepo conventions.

Use:
- name: @remix-run/<package-name>
- version (for brand-new packages): "0.0.0"
- type: "module"
- license: "MIT"
- repository.directory: packages/<package-name>
- homepage: https://github.com/remix-run/remix/tree/main/packages/<package-name>#readme
Include files:
- LICENSE
- README.md
- dist
- src
- !src/**/*.test.ts
Add standard scripts:
- build: tsgo -p tsconfig.build.json
- clean: git clean -fdX
- prepublishOnly: pnpm run build
- test: remix-test
- test:bun: bun x --bun remix-test
- typecheck: tsgo --noEmit
Use baseline dev dependencies:
- "@remix-run/assert": "workspace:^"
- "@remix-run/test": "workspace:^"
- "@types/node": "catalog:"
- "@typescript/native-preview": "catalog:"
Add keywords like existing packages (short, lowercase, feature-focused).

Define exports with src entry files only.

In exports, map each public subpath to a dedicated file in src.
Always include ./package.json.
Mirror each export in publishConfig.exports with dist output:
- types: ./dist/<entry>.d.ts
- default: ./dist/<entry>.js
Rule: every export must have a src file that re-exports from src/lib.
- Example: export ./foo -> src/foo.ts -> export { ... } from './lib/foo.ts'

Add TypeScript config files with shared defaults.

Use this tsconfig.json pattern:

{
  "compilerOptions": {
    "strict": true,
    "lib": ["ES2024", "DOM", "DOM.Iterable"],
    "module": "ES2022",
    "moduleResolution": "Bundler",
    "target": "ESNext",
    "allowImportingTsExtensions": true,
    "rewriteRelativeImportExtensions": true,
    "verbatimModuleSyntax": true
  }
}

Use this tsconfig.build.json pattern:

{
  "extends": "./tsconfig.json",
  "compilerOptions": {
    "declaration": true,
    "declarationMap": true,
    "outDir": "./dist"
  },
  "include": ["src"],
  "exclude": ["src/**/*.test.ts"]
}

Implement source structure and test setup.

Structure source as:
- src/<entry>.ts for public entry points
- src/lib/*.ts for implementation
- src/lib/*.test.ts for tests (colocated with implementation)
Tests use Remix's test runner:
- import * as assert from '@remix-run/assert'
- import { describe, it } from '@remix-run/test'
Keep tests IDE-friendly:
- Do not generate tests with loops/conditionals inside describe().

Follow monorepo code style rules while implementing.

Use import type { ... } and export type { ... } for types.
Include .ts extensions in relative imports.
Prefer let for locals; use const only at module scope.
Never use var.
Prefer function declarations/expressions for normal functions.
Use arrow functions for callbacks; use concise callbacks when returning a single expression.
Use object method shorthand (method() {}) instead of arrow properties.
Use native class fields and #private members.
Avoid Node-specific APIs when Web APIs are available.

Write README in the same style and section order as existing packages.

Start with:
- # <package-name>
- One short paragraph describing purpose.
Typical section order:
- ## Features
- ## Installation
- ## Usage
- Optional deep-dive sections (only if needed)
- ## Related Packages (if applicable)
- ## License
Installation instructions must always include installing the remix package.
If using the package requires a peer dependency, installation instructions must also include that peer dependency in the command.
Preferred installation pattern:

npm i remix

Example when a peer dependency is required:

npm i remix <peer-dependency>

Usage examples must always import from remix package exports, not from @remix-run/<package-name> directly.
License section format:
- See [LICENSE](https://github.com/remix-run/remix/blob/main/LICENSE)

Handle generated remix package updates deliberately.

packages/remix is generated automatically in CI.
Do not hand-edit packages/remix/package.json or packages/remix/src/*; run the generator when generated output is required.
When adding a new package, add it to packages/remix/manifest.json before running the generator:
- Add one entry per export: "remix/<canonical-path>": "@remix-run/<package-name>","remix/<canonical-path>/foo": "@remix-run/<package-name>/foo".
- Choose a domain-oriented canonical path (e.g. remix/middleware/logger, not remix/logger-middleware).
If user asks for full surfacing, you can still update root README.md package list when applicable.

Validate before finishing.

Run package checks:
- pnpm --filter @remix-run/<package-name> run typecheck
- pnpm --filter @remix-run/<package-name> run test
- pnpm --filter @remix-run/<package-name> run build
Run repo lint (required):
- pnpm run lint
Create packages/<package-name>/.changes/ on demand and add or update a change file when requested by contribution workflow.
For a brand-new package, the initial change file should use a minor. filename (for example, minor.initial-release.md) so the first release bumps 0.0.0 to 0.1.0.

Templates

Use this minimal src/index.ts style:

export { createThing, type ThingOptions } from './lib/thing.ts'

Use this minimal test style:

import * as assert from '@remix-run/assert'
import { describe, it } from '@remix-run/test'

import { createThing } from './thing.ts'

describe('createThing', () => {
  it('returns expected value', () => {
    let result = createThing()
    assert.equal(result, 'ok')
  })
})

add-package

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