feat: fiber architecture rewrite with lane-based scheduler and type safety

BREAKING CHANGE: Replaces the old hook-based reconciler with a full fiber
architecture modeled after React's internals. The public API surface remains
compatible, but the internal reconciliation engine is completely new.

## New Architecture
- **Fiber tree**: work-in-progress / current dual tree for interruptible renders
- **Work loop**:  and
- **Begin / Complete work**: separate phases for building and finalizing fibers
- **Commit phase**: mutation + layout effects, then passive effects flush
- **Lane-based priority system**: 16-bit branded  /  with merge,
  intersect, highest-priority selection, and entanglement
- **Scheduler**: binary min-heap () with ,
  , and priority-based task ordering
- **Concurrent rendering groundwork**: time-slicing ready, sync path still default

## Type Safety Hardening
- Centralised unsafe-cast boundary:  — all  /
   /  conversions live here; zero stray  elsewhere
-  alias resolves impossible branded-type incompatibilities
-  (bitwise OR produces  naturally)
- Compile-time enforcement:  with
   directives

## New Modules
-  — branded type conversion helpers
-  — binary min-heap for scheduler task queue
-  — work loop + sync + concurrent rendering paths
-  — begin work phase
-  — complete work phase
-  — DOM mutation helpers
-  — commit root orchestration
-  — priority task scheduler
-  — lane priority system
-  — child reconciliation with key-based diff
-  — hook implementations for fiber architecture
-  — effect collection and execution
-  — WIP tree management
-  — fiber factory functions
-  — runtime type guards and assertions
-  — SSR hydration support
-  — serialization / deserialization for SSR
-  — live Vite-powered browser demo

## Tests
- 9 new test modules covering previously untested internals
- 473 tests, 0 failures, 1,526 expectations across 38 files

## Verification
```bash
bun test          # 473 pass, 0 fail
bun run typecheck # 0 errors
```

Author: MarcelOlsen

.github/workflows/ci.yml

@@ -22,12 +22,15 @@ jobs:
       - name: 📦 Install dependencies
         run: bun install
 
-      - name: 🧪 Run tests
-        run: bun test
-
       - name: 🔍 Lint and format check
         run: bun run check
 
+      - name: 🔎 Typecheck
+        run: bun run typecheck
+
+      - name: 🧪 Run tests
+        run: bun test
+
       - name: 🏗️ Test build
         run: bun run build
 

.trae/rules/project_rules.md

@@ -60,27 +60,28 @@ Each phase includes clear specifications, working implementations, and extensive
 
 ## Current Status
 
-🆕 **Current Phase**: Stable Release Track - Phase 12 ✅ **COMPLETE**
+🆕 **Current Phase**: Stable Release Track - Phase 13 ✅ **COMPLETE**
 
 **Latest Achievements**:
 
-- ✅ **Phase 12 Complete**: Performance Optimization Suite - memo, useMemo, useCallback with comprehensive test coverage
-- ✅ **Enhanced Performance**: React.memo equivalent for component memoization and optimization hooks
-- ✅ **272 Tests Passing**: Comprehensive test suite covering all functionality including performance optimizations
-- ✅ **Zero Linter Issues**: Clean codebase with consistent formatting and biome configuration
-- ✅ **Complete Performance Toolkit**: memo, useMemo, useCallback hooks for production-grade optimization
-- ✅ **Production-Ready**: Robust error handling, TypeScript support, and comprehensive edge case coverage
-- ✅ **Package Preparation**: Ready for npm registry publication with performance features
+- ✅ **Fiber Reconciler**: Real React-like fiber architecture with work loop, begin/complete work, and commit phases
+- ✅ **Lane-Based Priorities**: Branded `Lane`/`Lanes` type system with priority scheduling and lane merging
+- ✅ **Scheduler**: Binary min-heap task queue with `scheduleCallback`, `shouldYield`, and priority levels
+- ✅ **Concurrent Rendering Groundwork**: `performConcurrentWorkOnRoot` with time-slicing support
+- ✅ **Type Safety Hardening**: Centralised unsafe-cast boundary (`bitwise.ts`), zero stray `as number` casts, compile-time enforcement
+- ✅ **473 Tests Passing**: Comprehensive test suite across 38 files with 1,526 expectations
+- ✅ **Zero Type Errors**: `bun typecheck` clean (0 errors)
+- ✅ **Interactive Showcase**: Live browser demo at `examples/interactive-showcase/`
 
-**Stable Release Progress**: 1/9 phases complete (11% complete) 🚀
+**Stable Release Progress**: 2/9 phases complete (22% complete) 🚀
 
 **Immediate Milestones**:
 
-- 🚀 **npm Package Publication**: Package will be available on npm registry soon
-- 📦 **Alpha Release v0.1.0**: Complete core React-like functionality now available
-- 📚 **Documentation & Examples**: Comprehensive guides and demo applications
+- 🚀 **npm Package v0.3.0**: Published with fiber reconciler and performance toolkit
+- 📚 **Documentation & Examples**: Interactive showcase + updated API docs
+- 🧪 **Testing & Quality Assurance**: Phase 19 test coverage underway
 
-**Post-Alpha Roadmap**: 12 additional phases planned for stable v1.0.0 release with advanced features including concurrent rendering, SSR, dev tools, and production optimizations.
+**Post-Alpha Roadmap**: 11 additional phases planned for stable v1.0.0 release with advanced features including concurrent rendering, SSR, dev tools, and production optimizations.
 
 ---
 
@@ -378,7 +379,7 @@ const App = () => {
 
 ### 📋 Testing & Quality
 
-- **261 Comprehensive Tests**: Full test coverage for all features and edge cases including all hooks
+- **473 Comprehensive Tests**: Full test coverage for all features and edge cases including all hooks
 - **TypeScript Support**: Full type safety with detailed type definitions
 - **Linting & Formatting**: Biome-based code quality and consistent formatting
 - **Error Handling**: Graceful degradation and helpful error messages
@@ -581,7 +582,7 @@ mini-react/
 - ✅ Advanced rendering (Portals, Fragments)
 - ✅ Production-ready reconciliation engine
 - ✅ Comprehensive TypeScript support
-- ✅ 261 tests with full coverage
+- ✅ 473 tests with full coverage
 - ✅ Developer-friendly API matching React patterns
 - ✅ npm package ready for publication
 

README.md

@@ -31,6 +31,12 @@
 				"noUnusedImports": "error",
 				"noUnusedVariables": "error"
 			},
+			"complexity": {
+				"useLiteralKeys": "off"
+			},
+			"style": {
+				"noNonNullAssertion": "error"
+			},
 			"security": {
 				"noGlobalEval": "warn"
 			}