Enable React Compiler for Portal (lazy-ref → useState)

.changeset/perf-remove-expensive-has-selectors.md

@@ -0,0 +1,5 @@
+---
+'@primer/react': patch
+---
+
+Improve rendering performance in Safari by removing expensive `:has()` selectors from ActionList/NavList, Breadcrumbs, SelectPanel, and SegmentedControl. No visual or API changes.

.changeset/silent-buses-knock.md

@@ -0,0 +1,14 @@
+---
+"@primer/react": minor
+---
+
+Add data-component attributes and associated tests for:
+
+SplitPageLayout
+Stack
+StateLabel
+SubNav
+TabNav
+Text
+TextArea
+ThemeProvider

.changeset/underline-nav-shared-overflow-observer.md

@@ -0,0 +1,5 @@
+---
+'@primer/react': patch
+---
+
+UnderlineNav, ActionBar: Detect item overflow with a single shared IntersectionObserver per component instead of one observer per item, reducing observer churn during resize. No public API changes.

.devcontainer/devcontainer.json

@@ -1,6 +1,6 @@
 {
   "name": "Primer React",
-  "image": "mcr.microsoft.com/vscode/devcontainers/typescript-node:24",
+  "image": "mcr.microsoft.com/vscode/devcontainers/typescript-node:26",
   "customizations": {
     "vscode": {
       "extensions": [
@@ -16,6 +16,9 @@
   "onCreateCommand": ["/bin/bash", "-c", "npm run setup"],
   "remoteUser": "node",
   "features": {
+    "ghcr.io/devcontainers/features/node:1": {
+      "version": "26.4.0"
+    },
     "ghcr.io/devcontainers/features/sshd:1": {
       "version": "latest"
     },

.github/copilot-instructions.md

@@ -26,6 +26,11 @@ The primary workspace is `packages/react` which contains the `@primer/react` pac
 - `npm run build` -- builds all packages. NEVER CANCEL. Takes 90 seconds without turbo cache, ~1 second with cache. Set timeout to 120+ minutes.
 - `npx turbo run build` -- builds all packages including example applications. Takes ~33 seconds.
 
+**Node.js version updates:**
+
+- When updating Node.js, update `.nvmrc` and `.devcontainer/devcontainer.json` together. Also check contributor documentation for any hardcoded Node.js version guidance, such as `contributor-docs/CONTRIBUTING.md`.
+- GitHub Actions workflows use `node-version-file: '.nvmrc'`; only update workflow files if they stop using `.nvmrc`.
+
 **Run tests:**
 
 - `npm test` -- runs unit tests. NEVER CANCEL. Takes 75 seconds. Set timeout to 90+ minutes. Runs 1500+ tests using Vitest in both node and chromium environments.
@@ -86,6 +91,7 @@ ComponentName/
 ├── index.ts              // Re-exports
 ├── ComponentName.tsx     // Main component
 ├── ComponentName.stories.tsx  // Storybook stories
+├── ComponentName.features.stories.tsx  // (optional) Storybook feature stories
 ├── ComponentName.test.tsx     // Unit tests
 ├── ComponentName.docs.json    // Documentation metadata
 └── __snapshots__/        // Test snapshots (being migrated to VRT)
@@ -95,7 +101,8 @@ ComponentName/
 
 - `*.module.css` -- CSS Modules for component styling
 - `*.test.tsx` -- Unit tests using Vitest and Testing Library
-- `*.stories.tsx` -- Storybook stories for documentation and testing
+- `[ComponentName].stories.tsx` -- Default Storybook stories for documentation and testing
+- `[ComponentName].features.stories.tsx` -- Storybook feature stories
 - `*.docs.json` -- Component metadata for documentation generation
 
 ## CI/CD and Workflows
@@ -104,7 +111,6 @@ ComponentName/
 
 - `.github/workflows/ci.yml` -- Main CI pipeline (format, lint, test, type-check, build)
 - `.github/workflows/vrt.yml` -- Visual regression testing
-- `.github/workflows/storybook-tests.yml` -- Storybook interaction tests
 
 **The CI will fail if:**
 
@@ -145,6 +151,13 @@ npm run lint:fix        # Auto-fix linting issues
 
 When working on UI components, always use the `primer-storybook` MCP tools to access Storybook's component and documentation knowledge before answering or taking any action. Reference the `.github/skills/storybook/SKILL.md` file for detailed instructions on using the Storybook MCP effectively and accurately.
 
+**Story conventions:**
+
+- Each component should have a default stories file colocated with the component (for most components: `packages/react/src/[ComponentName]/[ComponentName].stories.tsx`).
+- The default stories file should use the `Components/[ComponentName]` Storybook title and include `Default` and `Playground` stories when the component supports configurable controls.
+- Put feature-specific stories colocated with the component (for most components: `packages/react/src/[ComponentName]/[ComponentName].features.stories.tsx`) with the `Components/[ComponentName]/Features` Storybook title.
+- Keep examples or scenario-based stories in separate files, such as `[ComponentName].examples.stories.tsx`, when they are distinct from core feature coverage
+
 ## Slots
 
 When building, modifying, or wrapping compound components that use child-component "slots" (anything involving `__SLOT__`, `useSlots`, `isSlot`, or `asSlot`), reference the `.github/skills/slots/SKILL.md` file. It documents when to add slot markers, naming conventions for `Symbol(...)` descriptions, the public slot APIs, and common pitfalls.

.github/dependabot.yml

@@ -9,6 +9,8 @@ updates:
     directory: '/'
     schedule:
       interval: 'weekly'
+    cooldown:
+      default-days: 7
     versioning-strategy: increase
     labels:
       - 'dependencies'
@@ -31,11 +33,10 @@ updates:
           - '@types/react'
           - '@types/react-dom'
           - '@types/react-is'
-      rollup:
+      rolldown:
         patterns:
-          - '@rollup/*'
-          - 'rollup'
-          - 'rollup-plugin-*'
+          - '@rolldown/*'
+          - 'rolldown'
       storybook:
         patterns:
           - '@storybook/*'
@@ -49,6 +50,8 @@ updates:
     directory: '/'
     schedule:
       interval: 'weekly'
+    cooldown:
+      default-days: 7
     labels:
       - 'dependencies'
       - 'skip changeset'

.github/instructions/typescript-react.instructions.md

@@ -25,3 +25,12 @@ Apply the [general coding guidelines](./general-coding.instructions.md) to all c
 - Use React.FC type for components with children
 - Keep components small and focused
 - Use CSS modules for component styling
+
+## Storybook Guidelines
+
+- Put the default component stories alongside the component (for most components this is `packages/react/src/[ComponentName]/[ComponentName].stories.tsx`)
+- Include `Default` and `Playground` stories in the default stories file when the component supports configurable controls
+- Use the `Components/[ComponentName]` Storybook title for the default stories file
+- Put feature-specific stories alongside the component (for most components this is `packages/react/src/[ComponentName]/[ComponentName].features.stories.tsx`)
+- Use the `Components/[ComponentName]/Features` Storybook title for feature stories
+- Put examples or scenario-based stories in separate files, such as `[ComponentName].examples.stories.tsx`, when they are distinct from core feature coverage

.github/pull_request_template.md

@@ -34,16 +34,4 @@ Closes #
 <!-- Describe any specific details to help reviewers test or review this Pull Request -->
 <!-- To publish a canary release for integration testing, apply the "Canary Release" label to this PR -->
 
-### Merge checklist
-
-- [ ] Added/updated tests
-- [ ] Added/updated documentation
-- [ ] Added/updated previews (Storybook)
-- [ ] Changes are [SSR compatible](https://github.com/primer/react/blob/main/contributor-docs/CONTRIBUTING.md#ssr-compatibility)
-- [ ] Tested in Chrome
-- [ ] Tested in Firefox
-- [ ] Tested in Safari
-- [ ] Tested in Edge
-- [ ] (GitHub staff only) Integration tests pass at github/github-ui ([Learn more about how to run integration tests](https://github.com/github/primer-engineering/blob/main/how-we-work/testing-primer-react-pr-at-dotcom.md))
-
 <!-- Take a look at the [What we look for in reviews](https://github.com/primer/react/blob/main/contributor-docs/CONTRIBUTING.md#what-we-look-for-in-reviews) section of the contributing guidelines for more information on how we review PRs. -->

.github/workflows/aat-reports.yml

@@ -24,7 +24,7 @@ jobs:
           node-version-file: '.nvmrc'
           cache: 'npm'
       - name: Set up turbo cache
-        uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb
+        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9
         with:
           path: .turbo
           key: ${{ runner.os }}-turbo-${{ github.job }}-shard-${{ matrix.shard }}-${{ github.run_id }}-${{ github.run_attempt }}

.github/workflows/check_for_changeset.yml

@@ -15,11 +15,30 @@ jobs:
   check-for-changeset:
     name: Check for changeset
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: read
     steps:
-      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
       - name: 'Check for changeset'
-        uses: brettcannon/check-for-changed-files@v1
-        with:
-          file-pattern: '.changeset/*.md'
-          skip-label: 'skip changeset'
-          failure-message: 'No changeset found. If these changes should not result in a new version, apply the ${skip-label} label to this pull request. If these changes should result in a version bump, please add a changeset https://git.io/J6QvQ'
+        env:
+          GH_TOKEN: ${{ github.token }}
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+          SKIP_LABEL: 'skip changeset'
+        run: |
+          set -euo pipefail
+
+          if jq -r '.pull_request.labels[]?.name // empty' "$GITHUB_EVENT_PATH" | grep -Fxq "$SKIP_LABEL"; then
+            echo "The skip label \"$SKIP_LABEL\" is set"
+            exit 0
+          fi
+
+          changed_files="$(gh api --paginate "repos/$GITHUB_REPOSITORY/pulls/$PR_NUMBER/files" --jq '.[].filename')"
+
+          if grep -Eq '^\.changeset/[^/]+\.md$' <<<"$changed_files"; then
+            echo 'The ".changeset/*.md" file pattern matched the changed files of the pull request'
+            exit 0
+          fi
+
+          failure_message="No changeset found. If these changes should not result in a new version, apply the \"$SKIP_LABEL\" label to this pull request. If these changes should result in a version bump, please add a changeset https://git.io/J6QvQ"
+          echo "::error::$failure_message"
+          exit 1

.github/workflows/ci.yml

@@ -68,7 +68,7 @@ jobs:
           node-version-file: '.nvmrc'
           cache: 'npm'
       - name: Set up turbo cache
-        uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb
+        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9
         with:
           path: .turbo
           key: ${{ runner.os }}-turbo-${{ github.job }}-${{ matrix.react-version }}-${{ github.run_id }}-${{ github.run_attempt }}
@@ -103,7 +103,7 @@ jobs:
           node-version-file: '.nvmrc'
           cache: 'npm'
       - name: Set up turbo cache
-        uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb
+        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9
         with:
           path: .turbo
           key: ${{ runner.os }}-turbo-${{ github.job }}-${{ matrix.react-version }}-${{ github.run_id }}-${{ github.run_attempt }}
@@ -137,7 +137,7 @@ jobs:
           node-version-file: '.nvmrc'
           cache: 'npm'
       - name: Set up turbo cache
-        uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb
+        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9
         with:
           path: .turbo
           key: ${{ runner.os }}-turbo-${{ github.job }}-${{ matrix.react-version }}-${{ github.run_id }}-${{ github.run_attempt }}
@@ -164,7 +164,7 @@ jobs:
           node-version-file: '.nvmrc'
           cache: 'npm'
       - name: Set up turbo cache
-        uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb
+        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9
         with:
           path: .turbo
           key: ${{ runner.os }}-turbo-${{ github.job }}-default-${{ github.run_id }}-${{ github.run_attempt }}
@@ -194,7 +194,7 @@ jobs:
           node-version-file: '.nvmrc'
           cache: 'npm'
       - name: Set up turbo cache
-        uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb
+        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9
         with:
           path: .turbo
           key: ${{ runner.os }}-turbo-${{ github.job }}-default-${{ github.run_id }}-${{ github.run_attempt }}