diff --git a/DEVELOPMENT.md b/DEVELOPMENT.md
index 4d89058..a9c9571 100644
--- a/DEVELOPMENT.md
+++ b/DEVELOPMENT.md
@@ -1,19 +1,42 @@
 # Development Documentation
 
+## Quick reference
+
+| Task                          | Command                      |
+| ----------------------------- | ---------------------------- |
+| Run tests                     | `npm test` or `npm run test` |
+| Tests + coverage              | `npm run test-coverage`      |
+| Lint                          | `npm run lint`               |
+| Lint and fix                  | `npm run lint-fix`           |
+| Build                         | `npm run build`              |
+| Run from source               | `npm run dev`                |
+| Link package                  | `npm link` (see Build)       |
+| Run knip (for unused imports) | `npm run knip`               |
+
 ## Testing and Code Coverage
 
-### Running Tests
+### Run our test suite
 
-The project uses Vitest for testing. To run the test suite you can use:
+The project uses Vitest to write and run tests. To run the test suite use the
+command:
 
 ```bash
 npm test
 ```
 
-This runs all tests with code coverage analysis enabled.
+That runs all tests without a coverage report. If you want coverage (handy for
+seeing what's covered and what's now), use `npm run test-coverage`—see Coverage
+reports below.
+
+If you like running tests from VS Code, install the Vitest extension or use the
+built-in test runner so your tests are discovered and you can debug in the IDE.
+
+When you run the test suite it will default to running all tests and we continue
+to run in "watch" mode. This means that if you make changes to the code, the
+tests will automatically re-run.
 
-Note: if you want to run your tests locally in VS Code using the interactive
-IDE, be sure to install the Jest (orta) extension so your tests are discovered.
+To exit the watch mode, you can press `Ctrl+C` or `Command+C` depending on your
+operating system. Or hit `q` which prompt vitest to exit.
 
 ### Test Configuration
 
@@ -33,226 +56,189 @@ configuration file:
 
 Tests will fail if coverage drops below these thresholds.
 
+TODO: We likely want much higher coverage than this given the use of the project
+but for now we are slowly refactoring and improving coverage as we go.
+
 ### Coverage Reports
 
-Run `test-coverage` to generate coverage reports in the `coverage/` directory:
+Run `npm run test-coverage` to generate coverage reports in the `coverage/`
+directory:
 
-- **`coverage/lcov-report/index.html`** — Interactive HTML report (open in
-  browser)
+- **`coverage/lcov-report/index.html`** — Interactive HTML report (open in a
+  browser to explore)
 - **`coverage/lcov.info`** — LCOV format (used by Codecov)
 
-The HTML report provides a visual breakdown of which files are covered by tests.
+The HTML report gives you a visual breakdown of which files are covered by
+tests.
 
 ### Codecov Integration
 
 The project uses Codecov to track code coverage over time and on pull requests.
 
-#### CI Integration
+#### CI integration
 
-- The GitHub Actions workflow (`.github/workflows/test-deploy.yml`)
-  automatically uploads coverage to Codecov after running tests
+- The GitHub Actions workflow (`.github/workflows/test-deploy.yml`) uploads
+  coverage to Codecov after running tests
 - Coverage reports appear as comments on pull requests (if enabled)
 - The workflow uses `codecov/codecov-action@vxxx` (whatever version is most
   recent) to upload the `lcov.info` file
 
 #### Configuration
 
-Codecov behavior is configured in `.codecov.yml`:
+Codecov is configured in `.codecov.yml`:
 
 - Patch coverage is tracked (checks coverage of changed code in PRs)
 - Project-level status checks are disabled
 - PR comments are disabled
 - Codecov now requires a token for all uploads so we have one generated in the
-  repo as a secret `secrets.CODECOV_TOKEN`.
+  repo as a secret `secrets.CODECOV_TOKEN`. This token was generated by
+  `@lwasser` but it can be easily regenerated if a maintianer needs to do that.
 
-#### Local Usage
+#### Local usage
 
-You don't need a Codecov account to view coverage locally—just run `pnpm test`
-and open the HTML report. Codecov integration is primarily for tracking coverage
-trends and to simplify PR reviews in the CI/CD pipeline.
+You don't need a Codecov account to view coverage locally. Just run
+`npm run test-coverage` and open the HTML report. The Codecov integration is
+mainly for tracking coverage over time and for PR reviews in CI.
 
 ## Linting
 
-2026 update: The project is now using ESLint 9 and the flat config format. As we
-update things from the old config we will update this document to reflect the
-changes. Once the code base is stable and things work, we can delete some of the
-historical documentation. But for now this document can help us track design
-decisions and changes made.
-
-### Overview
-
-The project uses a native ESLint configuration that was migrated from
-kcd-scripts. The setup supports both CommonJS source files and ES module test
-files, using ESLint 9's flat config format.
-
-### What changed
-
-Previously, the project used `kcd-scripts` for linting configuration. Because
-that project is no longer actively maintained, we migrated to a native ESLint
-setup that replicates the same behavior.
-
-**Migration details:**
-
-- Replaced `kcd-scripts lint` with native ESLint
-- Created `eslint.config.mjs` using ESLint 9 flat config format
-- Extracted rules from `eslint-config-kentcdodds` to create a simplified,
-  maintainable config. This included removing a lot of the custom rules and
-  leaning more on the recommended rules.
-- Preserved some custom rule overrides from the original setup
-- Supports both CommonJS (source files) and ES modules (test files)
-
-Note: We should consider refacting the project to use ES modules instead of
-CommonJS (if everyone supports that) in the future for consistency.
+The project uses ESLint 9 with a native configuration (we migrated from
+kcd-scripts). The setup supports both CommonJS source files and ES module test
+files.
 
 ### How to run the linter
 
-To check for linting errors you can run:
+To check for linting errors:
 
 ```bash
 npm run lint
 ```
 
-ESlint can automatically fix some errors. to fix errors automatically run:
+To fix many issues automatically (recommended before committing):
 
 ```bash
-npm run lint -- --fix
+npm run lint-fix
 ```
 
-The `--fix` flag will automatically fix many common issues like:
+The fix command handles a lot of common issues, for example:
 
-- Vitest method aliases (e.g., `toThrowError()` → `toThrow()`)
+- Vitest method aliases (e.g. `toThrowError()` → `toThrow()`)
 - Unused eslint-disable directives
-- Some formatting issues
+- Many formatting issues
 
-**Note:** Some errors require manual fixes (e.g., unused variables, tests
-without assertions).
+Some things still need manual fixes (e.g. unused variables, tests without
+assertions), but lint-fix will get you most of the way there.
 
 ### Pre-commit hooks
 
-The project uses Husky to run pre-commit hooks that automatically lint and fix
-staged files before each commit.
+We use Husky so that staged files are linted and fixed before each commit. That
+way the codebase stays consistent without you having to remember to run lint
+every time.
 
-#### How it works:
+1. When you run `git commit`, Husky runs `lint-staged`.
+2. `lint-staged` runs `eslint --fix` and Prettier on staged JS/TS files.
+3. If everything passes, the commit goes through; if not, the commit is blocked
+   so you can fix the issues.
 
-1. When you run `git commit`, Husky intercepts the commit
-2. The pre-commit hook runs `lint-staged`
-3. `lint-staged` runs `eslint --fix` on all staged JavaScript/TypeScript files
-4. If linting passes, the commit proceeds; if it fails, the commit is blocked
+If the hook fails, run `npm run lint-fix` (see above) and address any remaining
+errors. If you're in a pinch, you can skip the hook once with
+`git commit --no-verify`—but if you do that, please mention it in your PR so a
+maintainer can help you get things passing.
 
-What this means... this workflow ensures that code is automatically linted and
-fixed before it's committed to version control.
+Husky and `lint-staged` are configured in `package.json`; the ESLint config
+lives in `eslint.config.mjs`.
 
-If you are encountering issues with the pre-commit hook, you can run the
-following command to manually lint and fix the files:
+### Dependencies
+
+These are the main packages we use for linting:
+
+- **eslint** — ESLint core
+- **@eslint/js** — Recommended rules
+- **eslint-plugin-import** — Import/export rules and module resolution
+- **@vitest/eslint-plugin** — Vitest-specific rules for test files
+- **globals** — Global variables for Node and Vitest environments
+
+### Configuration file
+
+The ESLint config is in `eslint.config.mjs` at the project root. It uses ESLint
+9's flat config format and includes:
+
+- Base rules from `eslint:recommended`
+- Import plugin rules
+- Vitest plugin rules (for test files only)
+- Custom overrides for project-specific needs
+- Support for both CommonJS and ES module syntax
+
+## Build and local testing
+
+The build has been migrated from `kcd-scripts build` to native Babel. After a
+build, the CLI runs from the `dist/` directory.
+
+### How to build
+
+From the repo root:
 
 ```bash
-npm run lint -- --fix
+npm run build
 ```
 
-Or if it's really problematic, you can skip verification and commit anyway with
-the `--no-verify` flag.
+That compiles `src/` into `dist/` using Babel (see `babel.config.js`). The entry
+point is `dist/cli.js`; you can also run it with `npm start`.
+
+### Running from source (no build)
+
+When you're developing, you often don't need to build. You can run the CLI from
+source instead:
 
 ```bash
-git commit --no-verify
+npm run dev
 ```
 
-If you do this please ping one of the maintainers in the PR that you open so
-they can help you fix the issues!
+That runs `./src/cli.js` directly. Use it when you're iterating; use the built
+package when you want to test the same code path that users get after they
+install from npm.
 
-**Configuration:**
+### Linking the package locally
 
-- Husky configuration is in `package.json` under the `husky.hooks.pre-commit`
-  field
-- `lint-staged` configuration is in `package.json` under the `lint-staged` field
-- The setup uses the native ESLint configuration (`eslint.config.mjs`)
+If you want to install the cli as if you'd installed it from npm you can do so
+by linking the package locally.
 
-**Note:** Previously, the project used `kcd-scripts pre-commit` which handled
-both hook management and linting. We migrated to using `lint-staged` directly
-with our native ESLint config to avoid version conflicts.
+1. In the CLI repo root, build and link the project:
+   ```bash
+   npm run build
+   npm link
+   ```
+2. In another directory (any repo that has a `.all-contributorsrc`, or wherever
+   you want to run the binary), the global `all-contributors` command will now
+   use your built package. run:
 
-### Dependencies
+   ```bash
+   all-contributors add <username> code
+   all-contributors generate
+   ```
 
-The following packages are typical starters for linting a JavaScript project:
+3. When you're done, you can unlink with `npm unlink -g all-contributors-cli` in
+   the CLI repo, and reinstall the real package elsewhere if you need to.
 
-- **eslint** — ESLint core
-- **@eslint/js** — ESLint recommended rules configuration
-- **eslint-plugin-import** — Import/export rules for module resolution and best
-  practices
-- **@vitest/eslint-plugin** — Vitest-specific rules for test files
-- **globals** — Provides properly formatted global variables for Node.js and
-  Vitest environments
+### Testing the linked package
 
-### Configuration file
+Once you've run `npm link`, switch to another directory and run
+`all-contributors` commands as you normally would. Confirm that behavior matches
+what you expect.
 
-The ESLint configuration is in `eslint.config.mjs` at the project root. It uses
-ESLint 9's flat config format and includes:
+Remember: after you change code in the CLI repo, run `npm run build` again
+before testing from the other directory. The link points at the built `dist/`
+output, so your latest changes won't show up until you rebuild.
 
-- Base rules from `eslint:recommended`
-- Import plugin rules
-- Vitest plugin rules (for test files only)
-- Custom overrides for project-specific needs
-- Support for both CommonJS and ES module syntax
+This workflow is a great way to double-check the built artifact and the exact
+code path users get when they install the package.
+
+### Build dependencies (migration notes)
+
+We removed most of the build dependencies that kcd-scripts used; they're
+redundant with current Node.
+
+Removed: `@babel/plugin-transform-class-properties`, `babel-plugin-macros`,
+`semver`, `@babel/runtime`.
 
-## Build system and process migration
-
-Our build system has been migrated from `kcd-scripts build` to native Babel.
-Below are the dependencies we add for the new native build and a description of
-what each does.
-
-For now we are keeping _some_ of the dependencies from the kcd-scripts build
-system. We might be able to remove others as we refine the build process and
-better get to know the project.
-
-### Build dependencies (from kcd-scripts → native Babel)
-
-- **@babel/core**
-  - **Status:** Required
-  - **Purpose:** The Babel compiler. Performs the actual transpilation (parse →
-    transform → generate).
-
-- **@babel/cli**
-  - **Status:** Required
-  - **Purpose:** Command-line interface. Runs `babel src --out-dir dist` and
-    feeds files to @babel/core.
-
-- **@babel/preset-env**
-  - **Status:** Required
-  - **Purpose:** Preset that compiles modern JS to match a target environment
-    (e.g. Node 22). Handles syntax and, optionally, module format.
-
-- **@babel/plugin-transform-runtime**
-  - **Status:** REMOVED
-  - **Purpose:** Replaces inlined Babel helpers with
-    `require('@babel/runtime/...')` so helpers live in one place. Keeps dist
-    smaller and avoids duplicating helper code in every file.
-
-- **@babel/plugin-transform-modules-commonjs**
-  - **Status:** REMOVED
-  - **Purpose:** Converts ES module syntax to CommonJS. Only needed if
-    preset-env is set with `modules: false`; if preset-env uses
-    `modules: 'commonjs'`, this plugin is redundant.
-
-- **@babel/plugin-transform-class-properties**
-  - **Status:** REMOVED
-  - **Purpose:** Transpiles class properties (including static) in loose mode.
-
-- **babel-plugin-macros**
-  - **Status:** Removed
-  - **Purpose:** Enables macro-based transforms (e.g. preval, codegen).
-    kcd-scripts includes it by default. We don't use macros in this project.
-
-- **semver**
-  - **Status:** Removed
-  - **Purpose:** Used in a config helper to read `engines.node` from
-    package.json and derive the target Node version. We hardcode our target
-    (e.g. `node: '22.22.0'`) in babel.config.js instead.
-
-- **@babel/runtime**
-  - **Status:** Required
-  - **Purpose:** Already a production dependency. Provides the helper functions
-    that `@babel/plugin-transform-runtime` injects imports for. Required at
-    runtime when using that plugin.
-
-IMPORTANT: there are still 2 bugs in the cli that i don't want to fix in this PR
-but the cli is broken. We can fix these bugs in a future pr and also add tests
-that will catch these bugs in the future.
+Kept: `@babel/cli`, `@babel/core` (and any others you see in `package.json`).
diff --git a/src/cli.js b/src/cli.js
index 359226a..4a11b71 100755
--- a/src/cli.js
+++ b/src/cli.js
@@ -70,14 +70,14 @@ function startGeneration(argv) {
 }
 
 async function addContribution(argv) {
-  // ensure the config file exists
-  await util.configFile.readConfig(argv.config)
+  const configData = await util.configFile.readConfig(argv.config)
+  Object.assign(argv, configData)
 
   const username = argv._[1] === undefined ? undefined : String(argv._[1])
   const contributions = argv._[2]
 
   // Add or update contributor in the config file
-  const data = updateContributors(argv, username, contributions)
+  const data = await updateContributors(argv, username, contributions)
 
   argv.contributors = data.contributors
 
@@ -189,4 +189,8 @@ async function run() {
   }
 }
 
-run()
+if (require.main === module) {
+  run()
+} else {
+  module.exports = {addContribution}
+}
diff --git a/src/contributors/__tests__/add.js b/src/contributors/__tests__/add.js
index 84ee3c9..4b79835 100644
--- a/src/contributors/__tests__/add.js
+++ b/src/contributors/__tests__/add.js
@@ -1,7 +1,14 @@
-import {test, expect} from 'vitest'
+import {test, expect, vi} from 'vitest'
 import addContributor from '../add.js'
 import fixtures from './fixtures/index.js'
 
+/**
+ * Mock function that simulates fetching contributor info from an API.
+ * Returns a promise resolving to contributor data without making real API calls.
+ *
+ * @param {string} username - GitHub username to fetch
+ * @returns {Promise<Object>} Contributor info (login, name, avatar_url, profile)
+ */
 function mockInfoFetcher(username) {
   return Promise.resolve({
     login: username,
@@ -11,6 +18,12 @@ function mockInfoFetcher(username) {
   })
 }
 
+/**
+ * Returns test options with one contributor that has a capitalized login ('Login1').
+ * Used for testing that case-insensitive username matching works correctly.
+ *
+ * @returns {Object} Options object with contributors array containing one entry
+ */
 function caseFixtures() {
   const options = {
     contributors: [
@@ -26,6 +39,10 @@ function caseFixtures() {
   return {options}
 }
 
+/**
+ * Tests that addContributor properly propagates errors when infoFetcher rejects.
+ * The same error should be returned without being swallowed or transformed.
+ */
 test('callback with error if infoFetcher fails', async () => {
   const {options} = fixtures()
   const username = 'login3'
@@ -44,6 +61,37 @@ test('callback with error if infoFetcher fails', async () => {
   expect(resolvedError).toBe(error)
 })
 
+/**
+ * Tests that addContributor calls infoFetcher with the correct arguments
+ * (username, repoType, and repoHost) when adding a new contributor.
+ * This ensures repository metadata is properly passed for API URL construction.
+ */
+test('calls infoFetcher with (username, options.repoType, options.repoHost) when adding new contributor', async () => {
+  const {options} = fixtures()
+  options.repoType = 'github'
+  options.repoHost = 'https://github.com'
+  const username = 'newuser'
+  const contributions = ['doc']
+  const infoFetcher = vi.fn().mockResolvedValue({
+    login: username,
+    name: 'New User',
+    avatar_url: '',
+    profile: '',
+  })
+
+  await addContributor(options, username, contributions, infoFetcher)
+
+  expect(infoFetcher).toHaveBeenCalledWith(
+    username,
+    'github',
+    'https://github.com',
+  )
+})
+
+/**
+ * Tests that a new contributor is added to the end of the existing contributors list
+ * with all required fields (login, name, avatar_url, profile, contributions).
+ */
 test('add new contributor at the end of the list of contributors', () => {
   const {options} = fixtures()
   const username = 'login3'
@@ -63,6 +111,10 @@ test('add new contributor at the end of the list of contributors', () => {
   )
 })
 
+/**
+ * Tests that contributions are stored as objects with type and url properties
+ * when options.url is provided, allowing contributions to link to specific resources.
+ */
 test('add new contributor at the end of the list of contributors with a url link', () => {
   const {options} = fixtures()
   const username = 'login3'
@@ -83,6 +135,10 @@ test('add new contributor at the end of the list of contributors with a url link
   )
 })
 
+/**
+ * Tests that addContributor responds accordingly when a contributor already has
+ * the exact same contribution types. The contributors list should remain unchanged.
+ */
 test(`should not update an existing contributor's contributions where nothing has changed`, () => {
   const {options} = fixtures()
   const username = 'login2'
@@ -95,6 +151,10 @@ test(`should not update an existing contributor's contributions where nothing ha
   )
 })
 
+/**
+ * Tests that username matching is case-insensitive. Adding contributions for 'login1'
+ * should match an existing 'Login1' contributor without creating duplicates.
+ */
 test(`should not update an existing contributor's contributions where nothing has changed but the casing`, () => {
   const {options} = caseFixtures()
   const username = 'login1'
@@ -107,6 +167,10 @@ test(`should not update an existing contributor's contributions where nothing ha
   )
 })
 
+/**
+ * Tests that adding a new contribution type to an existing contributor
+ * updates their contributions array while keeping the list length unchanged.
+ */
 test(`should update an existing contributor's contributions if a new type is added`, () => {
   const {options} = fixtures()
   const username = 'login1'
@@ -125,6 +189,10 @@ test(`should update an existing contributor's contributions if a new type is add
   )
 })
 
+/**
+ * Tests that case-insensitive matching works when updating contributions.
+ * Adding 'bug' for 'login1' should update 'Login1' while preserving the original casing.
+ */
 test(`should update an existing contributor's contributions if a new type is added with different username case`, () => {
   const {options} = caseFixtures()
   const username = 'login1'
@@ -143,6 +211,10 @@ test(`should update an existing contributor's contributions if a new type is add
   )
 })
 
+/**
+ * Tests that when adding a new contribution type with options.url set,
+ * the new contribution is stored as an object with type and url properties.
+ */
 test(`should update an existing contributor's contributions if a new type is added with a link`, () => {
   const {options} = fixtures()
   const username = 'login1'
@@ -163,6 +235,10 @@ test(`should update an existing contributor's contributions if a new type is add
   )
 })
 
+/**
+ * Tests that passing a subset of a contributor's current contributions
+ * replaces (not merges with) their contribution list, allowing removal of types.
+ */
 test(`should update an existing contributor's contributions if an existing type is removed`, () => {
   const {options} = fixtures()
   const username = 'login2'
diff --git a/src/contributors/__tests__/prompt.js b/src/contributors/__tests__/prompt.js
index eab98ed..a1795ad 100644
--- a/src/contributors/__tests__/prompt.js
+++ b/src/contributors/__tests__/prompt.js
@@ -1,8 +1,9 @@
 import {test, expect} from 'vitest'
-import prompt from '../prompt.js'
+import prompt, {getQuestions} from '../prompt.js'
 
 function fixtures() {
   const options = {
+    repoType: 'github',
     contributors: [
       {
         login: 'jfmengels',
@@ -58,3 +59,91 @@ test(`should filter valid contribution types from user inserted types`, () => {
     expect(answers.contributions).toEqual(['code', 'bug'])
   })
 })
+
+test(`should prompt for contributions when username is provided but contributions are undefined`, () => {
+  const options = fixtures()
+  const username = 'userName'
+  const contributions = undefined
+
+  const questions = getQuestions(options, username, contributions)
+  const contributionsQuestion = questions.find(q => q.name === 'contributions')
+
+  expect(contributionsQuestion).toBeDefined()
+  expect(contributionsQuestion.message).toBe('What are the contribution types?')
+})
+
+test(`should return prompt with username message when username and contributions are not provided`, () => {
+  const options = fixtures()
+  const username = undefined
+  const contributions = undefined
+  const questions = getQuestions(options, username, contributions)
+  const usernameQuestion = questions.find(q => q.name === 'username')
+  expect(usernameQuestion).toBeDefined()
+  expect(usernameQuestion.message).toBe(
+    "Oops. Missing something. What is the contributor's GitHub username?",
+  )
+})
+
+test(`username validation should return error when input is empty`, () => {
+  const options = fixtures()
+  const questions = getQuestions(options, undefined, undefined)
+  const usernameQuestion = questions.find(q => q.name === 'username')
+
+  const result = usernameQuestion.validate('')
+  expect(result).toBe('Username not provided')
+})
+
+test(`username validation should return true when input is provided`, () => {
+  const options = fixtures()
+  const questions = getQuestions(options, undefined, undefined)
+  const usernameQuestion = questions.find(q => q.name === 'username')
+
+  const result = usernameQuestion.validate('lwasser')
+  expect(result).toBe(true)
+})
+
+test(`contributions validation should return error when no contributions selected`, () => {
+  const options = fixtures()
+  const questions = getQuestions(options, 'userName', undefined)
+  const contributionsQuestion = questions.find(q => q.name === 'contributions')
+
+  // Simulate user selecting nothing (empty array)
+  const result = contributionsQuestion.validate([], {username: 'userName'})
+  expect(result).toBe('Use space to select at least one contribution type.')
+})
+
+test(`contributions validation should return error when selection matches previous contributions`, () => {
+  const options = {
+    repoType: 'github',
+    contributors: [
+      {
+        login: 'jfmengels',
+        name: 'Jeroen Engels',
+        contributions: ['code', 'doc'], // Existing contributions
+      },
+    ],
+  }
+
+  const questions = getQuestions(options, 'jfmengels', undefined)
+  const contributionsQuestion = questions.find(q => q.name === 'contributions')
+
+  // The user's contrib types already existing in the all-contribs file
+  const result = contributionsQuestion.validate(['code', 'doc'], {
+    username: 'jfmengels',
+  })
+  expect(result).toBe(
+    'Nothing changed, use space to select contribution types.',
+  )
+})
+
+test(`contributions validation should return true when valid selection is made`, () => {
+  const options = fixtures()
+  const questions = getQuestions(options, 'userName', undefined)
+  const contributionsQuestion = questions.find(q => q.name === 'contributions')
+
+  // Simulate user selecting valid contributions
+  const result = contributionsQuestion.validate(['code', 'doc'], {
+    username: 'userName',
+  })
+  expect(result).toBe(true)
+})
diff --git a/src/contributors/prompt.js b/src/contributors/prompt.js
index 58fdd90..a5a63e4 100644
--- a/src/contributors/prompt.js
+++ b/src/contributors/prompt.js
@@ -22,7 +22,7 @@ function getQuestions(options, username, contributions) {
     {
       type: 'input',
       name: 'username',
-      message: `What is the contributor's ${repo.getTypeName(
+      message: `Oops. Missing something. What is the contributor's ${repo.getTypeName(
         options.repoType,
       )} username?`,
       when: !username,
@@ -101,10 +101,15 @@ module.exports = function prompt(options, username, contributions) {
   const defaults = {
     username,
     contributions:
-      username === undefined && contributions === undefined
+      contributions === undefined
         ? []
         : getValidUserContributions(options, contributions),
   }
   const questions = getQuestions(options, username, contributions)
   return inquirer.prompt(questions).then(_.assign(defaults))
 }
+
+/** @testonly */
+module.exports.getQuestions = getQuestions
+/** @testonly */
+module.exports.getValidUserContributions = getValidUserContributions
diff --git a/src/generate/__tests__/index.js b/src/generate/__tests__/index.js
index a6a6a63..3454c43 100644
--- a/src/generate/__tests__/index.js
+++ b/src/generate/__tests__/index.js
@@ -2,6 +2,13 @@ import {test, expect} from 'vitest'
 import generate from '../index.js'
 import contributors from './fixtures/contributors.json'
 
+/**
+ * Returns test fixtures including options, sample contributor, and markdown content.
+ * The content includes ALL-CONTRIBUTORS-LIST comment tags where the contributor
+ * table should be injected.
+ *
+ * @returns {Object} Test data with options, jfmengels contributor, and sample content
+ */
 function fixtures() {
   const options = {
     projectOwner: 'kentcdodds',
@@ -35,6 +42,22 @@ function fixtures() {
   return {options, jfmengels, content}
 }
 
+/**
+ * Tests that generate throws an error when contributors is undefined.
+ * This prevents callers from forgetting to await the contributors promise
+ * before passing it to generate.
+ */
+test('throws when contributors is undefined (caller must await and pass resolved array)', () => {
+  const {options, content} = fixtures()
+  expect(() => generate(options, undefined, content)).toThrow(
+    /Cannot read properties of undefined \(reading 'length'\)/,
+  )
+})
+
+/**
+ * Tests that generate replaces content between ALL-CONTRIBUTORS-LIST tags
+ * with a properly formatted table of contributors.
+ */
 test('replace the content between the ALL-CONTRIBUTORS-LIST tags by a table of contributors', () => {
   const {kentcdodds, bogas04} = contributors
   const {options, jfmengels, content} = fixtures()
@@ -44,6 +67,10 @@ test('replace the content between the ALL-CONTRIBUTORS-LIST tags by a table of c
   expect(result).toMatchSnapshot()
 })
 
+/**
+ * Tests that generate includes a link to usage documentation when
+ * linkToUsage option is set to true.
+ */
 test('replace the content between the ALL-CONTRIBUTORS-LIST tags by a table of contributors with linkToUsage', () => {
   const {kentcdodds, bogas04} = contributors
   const {options, jfmengels, content} = fixtures()
@@ -57,6 +84,10 @@ test('replace the content between the ALL-CONTRIBUTORS-LIST tags by a table of c
   expect(result).toMatchSnapshot()
 })
 
+/**
+ * Tests that generate does not include a usage link when linkToUsage
+ * option is explicitly set to false.
+ */
 test('replace the content between the ALL-CONTRIBUTORS-LIST tags by a table of contributors without linkToUsage', () => {
   const {kentcdodds, bogas04} = contributors
   const {options, jfmengels, content} = fixtures()
@@ -70,6 +101,11 @@ test('replace the content between the ALL-CONTRIBUTORS-LIST tags by a table of c
   expect(result).toMatchSnapshot()
 })
 
+/**
+ * Tests that generate uses a custom wrapper template when provided.
+ * The wrapper template can contain <%= bodyContent %> to position the
+ * contributor list within custom HTML/markdown.
+ */
 test('replace the content between the ALL-CONTRIBUTORS-LIST tags by a custom wrapper around the list of contributors contained in the "bodyContent" tag', () => {
   const {kentcdodds, bogas04} = contributors
   const {options, jfmengels, content} = fixtures()
@@ -83,6 +119,10 @@ test('replace the content between the ALL-CONTRIBUTORS-LIST tags by a custom wra
   expect(result).toMatchSnapshot()
 })
 
+/**
+ * Tests that generate splits contributors into multiple table rows when
+ * the number of contributors exceeds the contributorsPerLine setting.
+ */
 test('split contributors into multiples lines when there are too many', () => {
   const {kentcdodds} = contributors
   const {options, content} = fixtures()
@@ -100,6 +140,10 @@ test('split contributors into multiples lines when there are too many', () => {
   expect(result).toMatchSnapshot()
 })
 
+/**
+ * Tests that generate splits contributors into multiple rows with linkToUsage
+ * enabled when there are more contributors than fit on one line.
+ */
 test('split contributors into multiples lines when there are too many with linkToUsage', () => {
   const {kentcdodds} = contributors
   const {options, content} = fixtures()
@@ -121,6 +165,11 @@ test('split contributors into multiples lines when there are too many with linkT
   expect(result).toMatchSnapshot()
 })
 
+/**
+ * Tests that generate sorts contributors alphabetically when
+ * contributorsSortAlphabetically option is true. The output should
+ * match regardless of the input order.
+ */
 test('sorts the list of contributors if contributorsSortAlphabetically=true', () => {
   const {kentcdodds, bogas04} = contributors
   const {options, jfmengels, content} = fixtures()
@@ -141,6 +190,10 @@ test('sorts the list of contributors if contributorsSortAlphabetically=true', ()
   expect(resultPreSorted).toEqual(resultAutoSorted)
 })
 
+/**
+ * Tests that generate returns the content unchanged when there are no
+ * ALL-CONTRIBUTORS-LIST tags present in the content.
+ */
 test('not inject anything if there is no tags to inject content in', () => {
   const {kentcdodds} = contributors
   const {options} = fixtures()
@@ -153,6 +206,10 @@ test('not inject anything if there is no tags to inject content in', () => {
   expect(result).toBe(content)
 })
 
+/**
+ * Tests that generate returns the content unchanged when the start tag
+ * is malformed (e.g., ALL-CONTRIBUTORS-LIST:SSSSSSSTART instead of :START).
+ */
 test('not inject anything if start tag is malformed', () => {
   const {kentcdodds} = contributors
   const {options} = fixtures()
@@ -171,6 +228,10 @@ test('not inject anything if start tag is malformed', () => {
   expect(result).toBe(content)
 })
 
+/**
+ * Tests that generate returns the content unchanged when the end tag
+ * is malformed (e.g., ALL-CONTRIBUTORS-LIST:EEEEEEEND instead of :END).
+ */
 test('not inject anything if end tag is malformed', () => {
   const {kentcdodds} = contributors
   const {options} = fixtures()
@@ -189,6 +250,10 @@ test('not inject anything if end tag is malformed', () => {
   expect(result).toBe(content)
 })
 
+/**
+ * Tests that generate injects only the comment structure (with prettier
+ * and markdownlint directives) when the contributors list is empty.
+ */
 test('inject nothing if there are no contributors', () => {
   const {options, content} = fixtures()
   const contributorList = []
@@ -215,6 +280,11 @@ test('inject nothing if there are no contributors', () => {
   expect(result).toBe(expected)
 })
 
+/**
+ * Tests that generate updates the all-contributors badge count when
+ * ALL-CONTRIBUTORS-BADGE tags are present in the content. The badge
+ * count should match the number of contributors.
+ */
 test('replace all-contributors badge if present', () => {
   const {kentcdodds} = contributors
   const {options} = fixtures()
@@ -253,6 +323,11 @@ test('replace all-contributors badge if present', () => {
   expect(result).toBe(expected)
 })
 
+/**
+ * Tests that generate correctly calculates cell width when contributorsPerLine
+ * results in a decimal value. The width should be floored to an integer to
+ * ensure valid HTML table attributes.
+ */
 test('validate if cell width attribute is floored correctly', () => {
   const {kentcdodds} = contributors
   const {options, content} = fixtures()