build: modernize renderer tooling and preserve Node 12 support

.c8rc

@@ -1,4 +1,10 @@
 {
   "reporter": ["lcov", "text"],
-  "extension": [".js"]
-}
+  "include": ["dist/**/*.js"],
+  "exclude-after-remap": false,
+  "check-coverage": true,
+  "statements": 100,
+  "functions": 100,
+  "lines": 100,
+  "branches": 95
+}

.editorconfig

@@ -2,18 +2,11 @@ root = true
 
 [*]
 indent_style = space
-indent_size = 4
+indent_size = 2
 end_of_line = lf
 charset = utf-8
-quote_type = single
 trim_trailing_whitespace = true
 insert_final_newline = true
 
-[{*.json,*.yaml,*.yml,*.jade,*.pss,*.css,*.js,*.md,.*,*.ts}]
-indent_size = 2
-
-[{changelog.md,.*}]
-insert_final_newline = false
-
 [*.md]
 trim_trailing_whitespace = false

.github/CONTRIBUTING.md

@@ -0,0 +1,77 @@
+# Contributing
+
+## Development
+
+Use Node.js 24, selected by `.nvmrc`:
+
+```sh
+nvm install
+nvm use
+npm ci
+npm run check
+```
+
+`check` builds with TypeScript, runs ESLint, checks current and minimum
+TypeScript consumers, runs the full suite with coverage, and verifies CommonJS
+and native ESM loading. `prepublishOnly` runs the same checks before publication.
+
+- `npm test` rebuilds and runs the suite with coverage.
+- `npm run test:unit` tests the existing build with `node:test`.
+- `npm run dev` watches TypeScript sources.
+- `npm run typecheck:minimum` checks TypeScript 4.3.5 consumers.
+
+Development tools require modern Node.js; the published renderer still supports
+Node.js 12 and newer. The parser 0.9 development dependency supplies a round-trip
+fixture that also works on the oldest runtime. Current parser integration is
+checked through PostHTML's packed-package suite.
+
+## Installed-package checks
+
+After `npm run check`, pack the built output and test it:
+
+```sh
+mkdir -p artifacts
+npm pack --ignore-scripts --pack-destination artifacts
+npm run test:packed -- artifacts/posthtml-render-3.0.0.tgz
+```
+
+Use the actual version in the tarball path. `test:packed` installs the production
+package in an isolated consumer, runs the complete shared synchronous suite and
+CJS/ESM consumers, then compiles standalone TypeScript consumers. Pass
+`--node /path/to/node` to run the JavaScript checks with another runtime while
+npm and TypeScript remain on Node.js 24. Failed fixtures are preserved for
+debugging; `POSTHTML_TEST_TMP` selects their temporary parent directory.
+
+CI builds one tarball on Node.js 24 and tests that artifact on Node.js 12.0,
+12/14/16/18/20/22/24/26. Native ESM checks use the historical experimental flag on
+Node.js versions before 12.17. Coverage reports are workflow artifacts.
+
+For coordinated changes, follow `AGENTS.md` and run the core packed tests with
+`--render /path/to/posthtml-render-<version>.tgz`.
+
+## Changes and pull requests
+
+- Keep commits focused, with short imperative subjects. Prefixes such as `fix:`,
+  `docs:` and `build:` are optional.
+- Include exact-output regression tests for changes to rendering behavior.
+- Keep coverage at 100% statements/functions/lines and at least 95% branches.
+- Check public declarations against TypeScript 4.3.5 and the current compiler.
+- Commit `package-lock.json` with dependency changes. Keep generated `dist/`,
+  coverage reports, tarballs and temporary consumers out of commits.
+- Add user-visible notes to `Unreleased` in `changelog.md`, preserving history.
+- Describe verification in the pull request. Checks run in CI and before npm
+  publication; no local Git hooks are installed.
+
+## Releases
+
+1. Prepare a release pull request. Update the version and lockfile with
+   `npm version <version> --no-git-tag-version`.
+2. Turn `Unreleased` into a dated version entry and start a new `Unreleased`
+   section above it. Maintain the changelog by hand.
+3. Run `npm run check`, test the tarball and validate it in PostHTML.
+4. Merge the release pull request after its checks pass. Tag the tested master
+   commit as `v<version>` and publish that checkout with `npm publish`.
+5. Verify the npm version/dist-tag and a fresh registry install before updating
+   the renderer dependency range in core.
+
+Publishing and pushing release tags require an explicit maintainer request.

.github/ISSUE_TEMPLATE.md

@@ -1,29 +1,17 @@
-> ✏️ Briefly describe the issue you are experiencing (or the feature you want to see added to the plugin). Tell us what you were trying to do and what happened instead. Remember, this is _not_ a place to ask questions. For that, go to http://gitter.im/posthtml/posthtml
+## Description
 
-### `Details`
+What happened, and what output did you expect?
 
-> ✏️ Describe in more detail the problem you have been experiencing, if necessary.
+## Reproduction
 
-## `Error (Logs|Stacks)`
+Include the input tree or HTML, renderer options, and a minimal runnable example.
 
-> 👉 Create a [gist](https://gist.github.com) which is a paste of your **full** logs, and link them here.
+## Environment
 
-> ⚠️ Do **not** paste your full logs here (or at least hide them by using a `<details></details>` block), as it will make this issue long and hard to read! If you are reporting a bug, **always** include logs!
+- posthtml-render version:
+- Node.js version:
+- Operating system:
 
-### `Reproduction (Code)`
+## Logs
 
-> ⚠️ Please remember that, with sample code; it's easier to reproduce a bug and much faster to fix it.
-
-> 🔗 Please refer to a simple code example.
-
-```bash
-$ git clone https://github.com/<user>/<sample>
-```
-
-### `Environment`
-
-> ℹ️ Please provide information about your current environment.
-
-|OS|node|npm/yarn|package|
-|:-:|:--:|:-:|:------:|
-|[name][version]|[version]|[version]|[version]|
+Include relevant errors or stack traces, if any.

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,55 +1,12 @@
-### `Notable Changes`
+## Summary
 
-> ✏️ Describe the big picture of your changes here to communicate to the maintainers why we should accept this pull request. If it fixes a bug or resolves a feature request, be sure to link to that issue down below.
+Describe the change and link any related issues.
 
-#### `Commit Message Summary (CHANGELOG)`
+## Compatibility
 
-```
-commit message body...
-```
+Describe changes to output, options, declarations or supported runtimes, if any.
 
-### `Type`
+## Verification
 
-> ℹ️  What types of changes does your code introduce?
-
-> 👉 _Put an `x` in the boxes that apply and delete all others_
-
-- [ ] CI
-- [ ] Fix
-- [ ] Perf
-- [ ] Docs
-- [ ] Test
-- [ ] Chore
-- [ ] Style
-- [ ] Build
-- [ ] Feature
-- [ ] Refactor
-
-### `SemVer`
-
-> ℹ️  What changes to the current `semver` range does your PR introduce?
-
-> 👉  _Put an `x` in the boxes that apply and delete all others_
-
-- [ ] Fix (:label: Patch)
-- [ ] Feature (:label: Minor)
-- [ ] Breaking Change (:label: Major)
-
-### `Issues`
-
-> ℹ️ What issue(s) (if any) are closed by your PR?
-
-> 👉  _Replace `#1` with the issue number that applies and remove the ``` ` ```_
-
-- Fixes `#1`
-
-### `Checklist`
-
-> ℹ️  You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. This is a reminder of what we are going to look for before merging your code.
-
-> 👉  _Put an `x` in the boxes that apply and delete all others._
-
-- [ ] Lint and unit tests pass with my changes
-- [ ] I have added tests that prove my fix is effective/works
-- [ ] I have added necessary documentation (if appropriate)
-- [ ] Any dependent changes are merged and published in downstream modules
+List the checks performed, including `npm run check`, tarball tests and any
+cross-package integration checks relevant to this change.

.github/workflows/nodejs.yml

@@ -1,39 +1,70 @@
-name: Actions Status
+name: build
+
 on:
+  push:
+    branches: [master]
   pull_request:
-    types: [opened, synchronize]
-    branches:
-      - master
-env:
-  CI: true
+    types: [opened, synchronize, reopened]
+    branches: [master]
+  workflow_dispatch:
+
+permissions:
+  contents: read
 
 jobs:
-  run:
-    name: Node ${{ matrix.node }} on ${{ matrix.os }}
-    runs-on: ${{ matrix.os }}
+  check:
+    name: Build and check (Node 24)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7.0.1
+      - uses: actions/setup-node@v7.1.0
+        with:
+          node-version-file: .nvmrc
+          cache: npm
+      - run: npm ci
+      - run: npm run check
+      - name: Upload coverage
+        uses: actions/upload-artifact@v7.0.2
+        with:
+          name: coverage
+          path: coverage/lcov.info
+          if-no-files-found: error
+      - name: Pack the checked build
+        run: |
+          mkdir artifacts
+          npm pack --ignore-scripts --pack-destination artifacts
+      - uses: actions/upload-artifact@v7.0.2
+        with:
+          name: npm-package
+          path: artifacts/*.tgz
+          if-no-files-found: error
 
+  runtime:
+    name: Packed runtime Node ${{ matrix.node }}
+    needs: check
+    runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
-        node: [12, 14, 16]
-        os: [ubuntu-latest]
-
+        node: ['12.0.0', '12', '14', '16', '18', '20', '22', '24', '26']
     steps:
-      - name: Clone repository
-        uses: actions/checkout@v2
-
-      - name: Set Node.js version
-        uses: actions/setup-node@v1
+      - uses: actions/checkout@v7.0.1
+      - name: Select the consumer runtime
+        uses: actions/setup-node@v7.1.0
         with:
           node-version: ${{ matrix.node }}
-
-      - name: Install npm dependencies
-        run: npm ci
-
-      - name: Run tests
-        run: npm run test
-
-      - name: Run Coveralls
-        uses: coverallsapp/github-action@master
+      - name: Record the consumer executable
+        id: runtime-path
+        run: echo "node=$(node -p process.execPath)" >> "$GITHUB_OUTPUT"
+      - name: Use development Node for npm and TypeScript
+        uses: actions/setup-node@v7.1.0
+        with:
+          node-version-file: .nvmrc
+          cache: npm
+      - run: npm ci --ignore-scripts
+      - uses: actions/download-artifact@v8.0.2
         with:
-          github-token: "${{ secrets.GITHUB_TOKEN }}"
+          name: npm-package
+          path: artifacts
+      - name: Run the complete suite and consumers against the tarball
+        run: npm run test:packed -- "artifacts/posthtml-render-$(node -p 'require("./package.json").version').tgz" --node "${{ steps.runtime-path.outputs.node }}"

.gitignore

@@ -2,4 +2,6 @@ node_modules
 coverage
 .nyc_output
 npm-debug.log
-dist
+dist
+artifacts
+*.tgz

.nvmrc

@@ -0,0 +1 @@
+24