Merge pull request #1 from maxmind/greg/eng-4043

ENG-4043: Add device tracking library

Author: horgh

.githooks/pre-commit

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+#!/bin/sh
+precious lint --staged

.github/dependabot.yml

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+version: 2
+updates:
+  - package-ecosystem: npm
+    directory: /
+    schedule:
+      interval: daily
+      time: '14:00'
+    open-pull-requests-limit: 20
+    groups:
+      minor-and-patch:
+        patterns:
+          - '*'
+        update-types:
+          - minor
+          - patch
+    cooldown:
+      default-days: 7
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: daily
+      time: '14:00'
+    cooldown:
+      default-days: 7

.github/workflows/codeql-analysis.yml

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+name: "Code scanning - action"
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+  schedule:
+    - cron: '0 3 * * 6'
+
+jobs:
+  CodeQL-Build:
+
+    runs-on: ubuntu-latest
+
+    permissions:
+      security-events: write
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      with:
+        fetch-depth: 2
+        persist-credentials: false
+
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@cdefb33c0f6224e58673d9004f47f7cb3e328b89 # v4.31.10
+
+    - name: Autobuild
+      uses: github/codeql-action/autobuild@cdefb33c0f6224e58673d9004f47f7cb3e328b89 # v4.31.10
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@cdefb33c0f6224e58673d9004f47f7cb3e328b89 # v4.31.10

.github/workflows/lint.yml

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+name: Precious
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+  schedule:
+    - cron: '3 0 * * SUN'
+  workflow_dispatch:
+permissions:
+  contents: read
+jobs:
+  precious:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          fetch-depth: 0
+          persist-credentials: false
+      - uses: jdx/mise-action@6d1e696aa24c1aa1bcc1adea0212707c71ab78a8 # v3.6.1
+      - run: pnpm install --frozen-lockfile
+      - name: Fetch base ref
+        if: ${{ github.event.pull_request }}
+        run: git fetch origin "${BASE_REF}"
+        env:
+          BASE_REF: ${{ github.base_ref }}
+      - name: Select files
+        id: select-files
+        run: |
+          if [[ -n "${PR_NUMBER}" ]]; then
+            echo "precious-args=--git-diff-from origin/${BASE_REF}" >> "$GITHUB_OUTPUT"
+          else
+            echo 'precious-args=--all' >> "$GITHUB_OUTPUT"
+          fi
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+          BASE_REF: ${{ github.base_ref }}
+      - name: Lint files
+        run: precious lint ${PRECIOUS_ARGS}
+        env:
+          PRECIOUS_ARGS: ${{ steps.select-files.outputs.precious-args }}

.github/workflows/release.yml

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+name: Release
+
+on:
+  workflow_dispatch:
+  pull_request:
+  push:
+    branches:
+      - main
+  release:
+    types: [published]
+
+permissions: {}
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+      - uses: jdx/mise-action@6d1e696aa24c1aa1bcc1adea0212707c71ab78a8 # v3.6.1
+      - run: pnpm install --frozen-lockfile
+      - run: pnpm test
+      - run: pnpm run lint
+      - run: pnpm run build
+
+  publish:
+    needs: build
+    if: github.event_name == 'release' && github.event.action == 'published'
+    runs-on: ubuntu-latest
+    environment: npm
+    permissions:
+      contents: write
+      id-token: write
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+      - uses: jdx/mise-action@6d1e696aa24c1aa1bcc1adea0212707c71ab78a8 # v3.6.1
+      - uses: actions/setup-node@6044e13b5dc448c55e2357c09f80417699197238 # v6.2.0
+        with:
+          registry-url: 'https://registry.npmjs.org'
+      - run: pnpm install --frozen-lockfile
+      - run: pnpm run build
+      - run: pnpm publish --provenance --no-git-checks
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}

.github/workflows/test.yml

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+name: Run tests
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+  schedule:
+    - cron: '3 2 * * SUN'
+permissions: {}
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+      - uses: jdx/mise-action@6d1e696aa24c1aa1bcc1adea0212707c71ab78a8 # v3.6.1
+      - run: pnpm install --frozen-lockfile
+      - run: pnpm test --coverage
+      - run: pnpm run build

.github/workflows/zizmor.yml

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+name: GitHub Actions Security Analysis with zizmor
+
+on:
+  push:
+    branches: ["main"]
+  pull_request:
+    branches: ["**"]
+
+permissions: {}
+
+jobs:
+  zizmor:
+    runs-on: ubuntu-latest
+    permissions:
+      security-events: write
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Run zizmor
+        uses: zizmorcore/zizmor-action@0dce2577a4760a2749d8cfb7a84b7d5585ebcb7d # v0.5.0

.precious.toml

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+[commands.eslint]
+type = "lint"
+cmd = ["pnpm", "exec", "eslint"]
+invoke = "once"
+include = ["src/**/*.ts"]
+ok-exit-codes = 0
+
+[commands.tsc]
+type = "lint"
+cmd = ["pnpm", "exec", "tsc", "--noEmit"]
+invoke = "once"
+path-args = "none"
+include = ["src/**/*.ts", "tsconfig.json"]
+ok-exit-codes = 0
+
+[commands.prettier]
+type = "both"
+cmd = ["pnpm", "exec", "prettier", "--parser", "typescript"]
+lint-flags = ["--check"]
+tidy-flags = ["--write"]
+path-args = "absolute-file"
+include = ["src/**/*.ts"]
+ok-exit-codes = 0

.prettierignore

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+dist/
+node_modules/
+pnpm-lock.yaml

CLAUDE.md

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+# @maxmind/device-tracking
+
+A thin TypeScript loader that validates inputs,
+dynamically imports a remote fingerprinting module from MaxMind's servers, and
+returns a device tracking token. Runs in the browser.
+
+## Commands
+
+```sh
+pnpm test              # Jest (ESM via --experimental-vm-modules)
+pnpm test:watch        # Jest in watch mode
+pnpm run lint          # ESLint + tsc --noEmit
+pnpm run build         # Clean build to dist/
+pnpm run prettier:ts   # Format src/**/*.ts
+```
+
+Run a single test file:
+
+```sh
+pnpm test -- src/loader.spec.ts
+```
+
+Jest prints an `ExperimentalWarning` about VM Modules on every run. This is
+expected and harmless.
+
+## Architecture
+
+```
+src/
+  index.ts          # Public API: trackDevice() with input validation
+  loader.ts         # Singleton module loader with caching and timeout
+  dynamic-import.ts # Thin wrapper around import() for test mocking
+  types.ts          # TrackDeviceOptions, TrackResult interfaces
+  *.spec.ts         # Co-located test files
+```
+
+- `index.ts` is the only public entry point (`package.json` exports map).
+- `loader.ts` caches module promises per-host; clears cache on failure for retry.
+- `dynamic-import.ts` exists solely to make `import()` mockable in Jest.
+- Tests use `jest.unstable_mockModule` (ESM-compatible mocking).
+
+## Conventions
+
+- **ESM only** — `"type": "module"` in package.json, `.js` extensions in imports.
+- **Strict TypeScript** — `strict: true`, target ES2022, module Node16.
+- **Prettier** — single quotes, trailing commas (es5).
+- **Formatting separate from logic** — keep style-only changes in their own commits.
+- **`fixup!` commits** — prefix fixup commits with `fixup! <original subject>` for autosquash.
+- **Error messages include context** — URLs, received values, types.
+- **`@internal` JSDoc tag** — marks exports that exist only for testing (e.g. `resetModuleCache`).
+
+## Testing notes
+
+- Test environment is jsdom (browser globals).
+- Tests co-locate next to source files (`*.spec.ts`).
+- The `moduleNameMapper` in jest.config.js strips `.js` extensions for ts-jest.
+- Loader tests use real dynamic import (which fails in Node) to exercise error paths.
+- Mocked-module tests use `jest.unstable_mockModule` + dynamic `import()` to get fresh modules.
+- Fake timers are used for timeout tests — always call `jest.useRealTimers()` in `afterEach`.
+
+## Tooling
+
+- **mise** manages Node, pnpm, and precious versions (see `mise.toml`).
+- **precious** is the code-quality runner (config: `.precious.toml`).
+- **Git hooks** live in `.githooks/`. Enable with: `git config core.hooksPath .githooks`
+- GitHub Actions: test, lint, CodeQL, zizmor, release workflows.