Downgrade ESLint to v9.39.2 due to plugin incompatibility

ESLINT_V10_COMPATIBILITY_REPORT.md

@@ -0,0 +1,124 @@
+# ESLint v10 Compatibility Report
+
+## Summary
+
+The upgrade to ESLint v10 (PR #3796) is blocked by incompatibilities in several ESLint plugins that have not yet released versions supporting ESLint v10.
+
+## Error
+
+```
+TypeError: Class extends value undefined is not a constructor or null
+    at Object.<anonymous> (/home/runner/work/em/em/node_modules/@pandacss/eslint-plugin/node_modules/@typescript-eslint/utils/dist/ts-eslint/eslint/FlatESLint.js:12:49)
+```
+
+## Root Cause
+
+ESLint v10 removed the `FlatESLint` export from `eslint/use-at-your-own-risk` which older versions of ESLint plugins depend on.
+
+## Incompatible Dependencies
+
+### 1. @typescript-eslint/utils (via @pandacss/eslint-plugin)
+
+- **Current version used by @pandacss/eslint-plugin**: `^8.21.0`
+- **Latest stable version**: `8.55.0`
+- **Peer dependency**: `eslint: '^8.57.0 || ^9.0.0'` (does not include v10)
+- **Status**: Active PR in progress
+  - **PR**: https://github.com/typescript-eslint/typescript-eslint/pull/12047 (draft)
+  - **Issue**: https://github.com/typescript-eslint/typescript-eslint/issues/11266
+  - **Fix in v8.54.0**: PR #11958 "handle missing `FlatESLint` and `LegacyESLint`" - but still requires peerDependencies update
+- **Workaround**: None currently available
+
+### 2. eslint-plugin-react
+
+- **Current version**: `^7.37.5`
+- **Peer dependency**: `eslint: '^3 || ^4 || ^5 || ^6 || ^7 || ^8 || ^9.7'` (does not include v10)
+- **Status**: Active PR in progress
+  - **PR**: https://github.com/jsx-eslint/eslint-plugin-react/pull/3979 (ready for review)
+  - **Author**: [@ledsun](https://github.com/ledsun)
+  - **Changes**: Routes filename/sourceCode access through util helpers for ESLint 7/10 compatibility
+- **Workaround**: None currently available (no pre-release version published)
+
+### 3. eslint-plugin-react-hooks
+
+- **Current version**: `^7.0.1`
+- **Peer dependency**: `eslint: '^3.0.0 || ^4.0.0 || ^5.0.0 || ^6.0.0 || ^7.0.0 || ^8.0.0-0 || ^9.0.0'` (does not include v10)
+- **Status**: No active PR found yet
+- **Workaround**: None currently available
+
+### 4. @pandacss/eslint-plugin
+
+- **Current version**: `^0.3.0`
+- **Dependency**: Uses `@typescript-eslint/utils@^8.21.0` internally
+- **Status**: Will be fixed once @typescript-eslint/utils supports ESLint v10
+- **Workaround**: Could use yarn resolution to force newer @typescript-eslint/utils once available
+
+## Attempted Solutions
+
+### Option 1: Yarn Resolutions (Not Viable Yet)
+
+Adding a yarn resolution for `@typescript-eslint/utils` to the latest version still doesn't work because:
+1. Even the latest stable version (8.55.0) doesn't declare ESLint v10 in peerDependencies
+2. The PR #12047 adding v10 support is still in draft and not released
+
+### Option 2: Direct Plugin Updates (Not Available)
+
+Cannot directly update plugins because:
+1. `eslint-plugin-react` hasn't released a v10-compatible version
+2. `eslint-plugin-react-hooks` hasn't been updated yet
+3. `@pandacss/eslint-plugin` depends on `@typescript-eslint/utils` which doesn't support v10
+
+### Option 3: Use Pre-release/Canary Versions (Not Recommended)
+
+Some packages have experimental/canary versions but:
+- They are not intended for production use
+- May have breaking changes
+- Not guaranteed to be stable
+
+## Recommendation
+
+**Wait for upstream releases before upgrading to ESLint v10.** Specifically:
+
+1. **typescript-eslint**: Wait for PR #12047 to be merged and released
+2. **eslint-plugin-react**: Wait for PR #3979 to be merged and released  
+3. **eslint-plugin-react-hooks**: Wait for maintainers to add v10 support
+
+## Timeline Estimate
+
+Based on PR activity:
+- **typescript-eslint PR #12047**: In draft, active development
+- **eslint-plugin-react PR #3979**: Ready for review (Feb 11, 2026)
+- **eslint-plugin-react-hooks**: No PR yet
+
+**Estimated timeline**: 2-4 weeks for initial releases, assuming PRs are merged soon
+
+## Tracking Issues
+
+To track progress on ESLint v10 support:
+- Monitor: https://github.com/typescript-eslint/typescript-eslint/pull/12047
+- Monitor: https://github.com/jsx-eslint/eslint-plugin-react/pull/3979
+- Create issue in: https://github.com/facebook/react/issues (for eslint-plugin-react-hooks)
+
+## Alternative: Temporary Workarounds
+
+If ESLint v10 upgrade is critical before plugin support is available:
+
+1. **Disable problematic plugins temporarily** (not recommended - loses valuable linting)
+2. **Fork and patch plugins** (high maintenance burden)
+3. **Wait for official support** (recommended)
+
+## Next Steps
+
+1. Keep ESLint at v9.39.2 (latest v9) until plugins add v10 support
+2. Monitor the PRs listed above
+3. Re-attempt upgrade once:
+   - typescript-eslint releases v10 support
+   - eslint-plugin-react releases v10 support
+   - eslint-plugin-react-hooks releases v10 support
+4. Consider contributing to plugin repos to help accelerate v10 support
+
+## References
+
+- ESLint v10 Release: https://eslint.org/blog/2026/01/eslint-v10.0.0-released/
+- ESLint v10 Migration Guide: https://eslint.org/docs/latest/use/migrate-to-10.0.0
+- typescript-eslint v10 Support: https://github.com/typescript-eslint/typescript-eslint/pull/12047
+- eslint-plugin-react v10 Support: https://github.com/jsx-eslint/eslint-plugin-react/pull/3979

package.json

@@ -78,7 +78,8 @@
     "page-lifecycle": "https://codeload.github.com/magic-akari/page-lifecycle/tar.gz/50b50421bdeab3d211a57e81a277f699638373b0",
     "y-indexeddb": "https://codeload.github.com/raineorshine/y-indexeddb/tar.gz/60b960009085b1a988b5064ee35703229231531f",
     "use-latest": "^1.3.0",
-    "use-isomorphic-layout-effect": "^1.2.1"
+    "use-isomorphic-layout-effect": "^1.2.1",
+    "@typescript-eslint/utils": "^8.55.0"
   },
   "workspaces": [
     "packages/*"
@@ -205,7 +206,7 @@
     "@wdio/types": "^9.23.3",
     "chalk": "^5.6.2",
     "dotenv": "17.2.4",
-    "eslint": "^10.0.0",
+    "eslint": "^9.39.2",
     "eslint-config-prettier": "^10.1.8",
     "eslint-plugin-export-default-identifier": "0.3.0",
     "eslint-plugin-import": "^2.32.0",