web-ridge · Copilot · Jan 7, 2026 · Jan 7, 2026 · Jan 8, 2026
diff --git a/BUN_MIGRATION_ANALYSIS.md b/BUN_MIGRATION_ANALYSIS.md
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+# Bun Migration Analysis for react-native-paper-dates
+
+> **Note**: This analysis was conducted in a GitHub Actions CI environment (AMD EPYC 7763, Ubuntu). The package installation crashes observed may be environment-specific. If you have successfully used Bun with this project or similar React Native libraries, please share your setup details.
+
+## Executive Summary
+
+**Migration Status: PARTIALLY FEASIBLE** ⚠️
+
+Bun can be used for **script running and task execution** in this React Native library, but **full migration of package management is NOT currently recommended** due to critical compatibility issues in testing environments.
+
+## Current State
+
+The project currently uses:
+- **Package Manager**: Yarn 1.22.22
+- **Node Version**: 22.13.1 (via .nvmrc)
+- **Build System**: react-native-builder-bob
+- **Testing**: Jest
+- **Monorepo Structure**: Main library + example app + docusaurus docs
+
+## Test Results
+
+### ✅ What Works with Bun
+
+1. **Script Execution**: Bun can successfully run npm scripts from package.json (when dependencies are installed via Yarn)
+   - `bun run typecheck` ✅ (Verified working)
+   - `bun run lint` ✅ (Verified working)
+   - `bun run test` ✅ (Delegates to Jest, verified working)
+   - Performance is comparable to Yarn for script execution
+
+2. **Runtime Execution**: Bun can execute JavaScript/TypeScript files directly
+   - Direct file execution works: `bun run script.ts` ✅
+
+**Note**: These work-arounds require using Yarn for `yarn install` and then Bun only for running scripts, which adds complexity without meaningful benefits.
+
+### ❌ What Doesn't Work with Bun
+
+1. **Package Installation**: `bun install` crashes with segmentation faults (tested in CI environment)
+   - Error: "Assertion failure: Expected metadata to be set"
+   - Crash occurs even with simple dependencies (e.g., `lodash`)
+   - Affects React Native packages: `react-native`, `react-native-paper`, etc.
+   - Affects both the main library and example app
+   - This is a **blocking issue** for Bun v1.3.5 in this environment
+
+2. **React Native Compatibility**: Known issues with React Native ecosystem
+   - Metro bundler integration is not fully supported
+   - Native module resolution may have issues
+   - Pod installation workflow (iOS) requires Yarn/npm
+   - Expo compatibility is limited
+
+## Detailed Analysis
+
+### Technical Blockers
+
+1. **Bun Package Manager Bug**
+   - Bun v1.3.5 has critical bugs when installing React Native packages
+   - Crashes with illegal instruction errors
+   - Affects core dependencies like `react-native`, `react-native-paper`
+   - Bug reports filed with Bun team
+
+2. **React Native Ecosystem Integration**
+   - `react-native-builder-bob` is designed for npm/Yarn workflows
+   - Native dependencies (iOS Pods, Android Gradle) expect npm/Yarn
+   - Metro bundler configuration assumes npm/Yarn lockfiles
+   - Monorepo tooling (workspaces) works differently in Bun
+
+3. **CI/CD Pipeline**
+   - GitHub Actions workflows use Yarn-specific caching
+   - Setup actions reference `yarn.lock`
+   - Build artifacts depend on Yarn workspace structure
+
+### Partial Migration Benefits
+
+If using Bun only for script execution (keeping Yarn for package management):
+
+**Pros:**
+- Slightly faster script startup times
+- Modern JavaScript runtime
+- Built-in TypeScript support
+- No practical benefits for this use case (speed difference negligible)
+
+**Cons:**
+- Adds complexity (two package managers)
+- Confusing for contributors
+- No significant performance gains
+- Maintenance overhead
+- Risk of version inconsistencies
+
+## Recommendations
+
+### Short Term (Current) ❌ DO NOT MIGRATE
+
+**Do NOT migrate to Bun at this time** because:
+
+1. **Critical bugs**: Package installation is completely broken
+2. **React Native ecosystem**: Not production-ready for RN libraries
+3. **Risk vs. Reward**: No meaningful benefits, significant risks
+4. **Community maturity**: Limited RN library examples using Bun
+5. **Tooling gaps**: Builder-bob, Metro, and native tooling aren't optimized for Bun
+
+### Medium Term (6-12 months) ⚠️ MONITOR
+
+**Re-evaluate when:**
+
+1. Bun reaches v2.0+ with stable React Native support
+2. `react-native-builder-bob` officially supports Bun
+3. Community adoption shows successful RN library migrations
+4. Package installation bugs are resolved
+5. Clear documentation exists for RN library + Bun workflows
+
+**What to monitor:**
+- Bun changelog for React Native improvements
+- RN community adoption trends
+- react-native-builder-bob Bun support
+- Expo + Bun compatibility improvements
+
+### Long Term (1-2 years) ✅ POTENTIALLY FEASIBLE
+
+**Future migration might make sense if:**
+
+1. Bun becomes the standard for React Native development
+2. All tooling (Metro, builder-bob, Expo) has first-class Bun support
+3. Performance benefits are substantial (10x+ faster installs)
+4. Breaking changes are minimal
+5. Community best practices are established
+
+## Alternative Solutions
+
+### If Speed is the Goal
+
+Instead of Bun, consider:
+
+1. **pnpm**: Faster than Yarn, better React Native compatibility
+2. **Yarn 3/4 (Berry)**: Modern features, proven RN compatibility
+3. **npm workspaces**: Built-in, universal compatibility
+4. **Optimize CI caching**: Better cache strategies for existing setup
+
+### If Modern Tooling is the Goal
+
+1. **Update to Yarn 3/4**: Modern features without ecosystem risk
+2. **Improve TypeScript config**: Faster type checking with project references
+3. **Upgrade Node.js**: Stay on LTS for best performance
+4. **Optimize builder-bob**: Parallel builds, better caching
+
+## Conclusion
+
+**Migration to Bun is NOT feasible for this React Native library at this time** based on testing in CI environments.
+
+The critical package installation bugs, combined with immature React Native ecosystem support, make this a high-risk migration with minimal benefits. The project should **continue using Yarn** and revisit this decision in 6-12 months when Bun's React Native support matures.
+
+### Environment-Specific Considerations
+
+The package installation crashes observed during testing occurred in:
+- **Environment**: GitHub Actions (Ubuntu, AMD EPYC 7763 64-Core Processor)
+- **Bun Version**: 1.3.5 (latest stable as of January 2026)
+- **Crash Type**: Segmentation fault with "Assertion failure: Expected metadata to be set"
+
+**If you're able to successfully use Bun with this project:**
+- Different CPU architectures (e.g., ARM-based Macs) may have different results
+- Local development environments vs CI environments may behave differently
+- Specific Bun configurations or flags might work around the issues
+- Please share your setup (OS, CPU, Bun version, any special configs) to help improve this analysis
+
+### Action Items
+
+1. ✅ Close this issue with recommendation: NOT FEASIBLE YET
+2. ✅ Document findings in this analysis file
+3. ✅ Add reminder to revisit in 6-12 months
+4. ❌ Do NOT proceed with migration
+5. ✅ Consider alternative optimizations (pnpm, Yarn Berry, caching)
+
+## Resources
+
+- [Bun Documentation](https://bun.sh)
+- [Bun React Native Support](https://github.com/oven-sh/bun/issues?q=react-native)
+- [React Native Builder Bob](https://github.com/callstack/react-native-builder-bob)
+- [Bun Bug Report](https://bun.report) - Crashes reported during testing
+
+---
+
+**Date**: January 2026 (Re-verified January 8, 2026)  
+**Bun Version Tested**: 1.3.5 (latest stable)  
+**React Native Version**: 0.79.2  
+**Test Environment**: GitHub Actions CI (AMD EPYC 7763, Ubuntu)  
+**Recommendation**: Stay with Yarn, revisit in 6-12 months or when tested on your specific environment