# LokaScript: Roadmap to 100% Expression Compatibility

## Current Status: 96.3% → Target: 100%

**Gap Analysis**: 54 failing tests out of 1464 total (3.7% gap to close)

## Phase 1: Critical Gap Analysis and Prioritization

### 🎯 **Todo 1: Analyze Remaining 3.7% Compatibility Gaps**

**Goal**: Systematically identify and categorize the 54 failing tests to understand root causes.

**Actions**:

- [ ] Run comprehensive test analysis to categorize failure types
- [ ] Map failures to specific \_hyperscript features/patterns
- [ ] Prioritize fixes by impact and difficulty
- [ ] Create focused test suites for each gap category

**Expected Output**: Detailed failure analysis report with prioritized fix list

**Commands**:

```bash
npm test src/expressions/ 2>&1 | grep -E "(FAIL|×)" > failed_tests.log
npm run compatibility:monitor --detailed-analysis
```

---

## Phase 2: Positional Expression Completeness

### 🎯 **Todo 2: Fix Positional Expression Edge Cases**

**Goal**: Achieve 100% compatibility for `first`/`last` expressions with all collection types.

**Current Status**: 92.3% (48/52 tests passing)

**Known Issues**:

- `first` with empty collections not returning null consistently
- `last` with CSS selector results failing
- Complex nested collection handling

**Actions**:

- [ ] Fix `first` expression null-safety for empty collections
- [ ] Enhance `last` expression CSS selector result handling
- [ ] Add support for `first`/`last` with nested collections
- [ ] Implement proper error propagation for invalid collection types

**Test Files to Fix**:

- `src/expressions/missing-expression-features-fix.test.ts` (lines 85-120)
- `src/expressions/positional/index.test.ts`

**Implementation Location**: `src/expressions/enhanced-positional/index.ts`

---

## Phase 3: Advanced Language Features

### 🎯 **Todo 3: Implement Null-Safe Property Access Operator**

**Goal**: Add `?.` operator for safe property access to match modern JavaScript standards.

**Current Gap**: `config.nonexistent?.property` patterns failing

**Actions**:

- [ ] Extend tokenizer to recognize `?.` operator
- [ ] Add null-safe property access AST node type
- [ ] Implement null-safe evaluation logic
- [ ] Add comprehensive test coverage for edge cases

**Implementation Files**:

- `src/parser/tokenizer.ts` - Add `?.` token recognition
- `src/parser/expression-parser.ts` - Add null-safe parsing logic
- `src/types/core.ts` - Add AST node type

### 🎯 **Todo 4: Add Nested Template Literal Support**

**Goal**: Support recursive template literal evaluation for complex string interpolation.

**Current Gap**: `` `Outer ${`inner ${variable}`}` `` patterns failing

**Actions**:

- [ ] Enhance template literal parser for nested structures
- [ ] Implement recursive interpolation evaluation
- [ ] Add proper escaping and quote handling
- [ ] Validate performance with deeply nested templates

**Test Case**: `src/expressions/advanced-patterns.test.ts:122`

---

## Phase 4: Type System and Coercion

### 🎯 **Todo 5: Fix Boolean Coercion Edge Cases**

**Goal**: Match official \_hyperscript boolean coercion behavior exactly.

**Current Issue**: Some comparison operations not handling type coercion correctly

**Actions**:

- [ ] Audit all comparison operators for coercion consistency
- [ ] Fix `==` vs `===` behavior to match \_hyperscript exactly
- [ ] Enhance number/string/boolean automatic conversions
- [ ] Add edge case tests for null/undefined coercion

**Test Files**:

- `src/expressions/comparison-operators-fix.test.ts:129`
- `src/expressions/enhanced-logical/index.test.ts`

---

## Phase 5: Advanced CSS and DOM Features

### 🎯 **Todo 6: Implement Complex CSS Selector Tokenization**

**Goal**: Support all advanced CSS selector patterns that \_hyperscript supports.

**Remaining Gaps**:

- Multiple attribute selectors: `<[data-id][class*="item"]/>`
- Complex pseudo-selectors with parentheses
- CSS selector validation and error reporting

**Actions**:

- [ ] Enhance CSS selector parser for complex patterns
- [ ] Add support for multiple attribute combinations
- [ ] Implement proper CSS selector validation
- [ ] Add detailed error messages for invalid selectors

**Test Case**: `src/expressions/advanced-patterns.test.ts:148`

---

## Phase 6: Missing Hyperscript Features

### 🎯 **Todo 7: Add Missing Hyperscript-Specific Operators**

**Goal**: Implement all remaining \_hyperscript operators and functions.

**Missing Features Analysis Needed**:

- [ ] Audit official \_hyperscript documentation for missing operators
- [ ] Implement `closest` with advanced patterns
- [ ] Add support for `previous`/`next` sibling navigation
- [ ] Implement `event` context handling
- [ ] Add `trigger` and `send` expression support

**Actions**:

- [ ] Create comprehensive \_hyperscript feature audit
- [ ] Implement missing DOM navigation expressions
- [ ] Add event-related expression support
- [ ] Create compatibility test matrix

---

## Phase 7: Error Handling and Edge Cases

### 🎯 **Todo 8: Enhance Error Handling to Match Official Behavior**

**Goal**: Error handling should match \_hyperscript exactly - fail gracefully where expected, throw where appropriate.

**Current Issues**:

- Some null property access should return null, not throw
- Undefined variable handling inconsistency
- Error message format differences

**Actions**:

- [ ] Audit all error handling against official \_hyperscript behavior
- [ ] Implement graceful degradation for expected failure cases
- [ ] Standardize error messages and types
- [ ] Add comprehensive error handling test suite

**Test Files with Errors**:

- `src/expressions/advanced-patterns.test.ts:165-175`

---

## Phase 8: Validation and Performance

### 🎯 **Todo 9: Validate 100% Compatibility**

**Goal**: Comprehensive validation that all \_hyperscript patterns work correctly.

**Actions**:

- [ ] Create complete official \_hyperscript test matrix
- [ ] Run exhaustive compatibility test suite
- [ ] Cross-reference with official \_hyperscript test cases
- [ ] Document any intentional differences (if any)

**Validation Commands**:

```bash
npm test # Should show 1464/1464 tests passing
npm run compatibility:monitor # Should show 100% scores
npm run compatibility:dashboard # Visual confirmation
```

### 🎯 **Todo 10: Performance Optimization for 100% Compatible Features**

**Goal**: Ensure 100% compatibility doesn't come at performance cost.

**Actions**:

- [ ] Run performance benchmarks on all new features
- [ ] Optimize any slow paths introduced during compatibility fixes
- [ ] Validate memory usage remains efficient
- [ ] Ensure bundle size stays optimized

**Performance Targets**:

- Expression evaluation: <10ms average (maintain current)
- Throughput: >100 ops/sec (maintain current)
- Memory: Minimal allocation increase
- Bundle size: <5% increase acceptable

---

## Implementation Strategy

### Development Approach

1. **TDD First**: Write failing tests for each gap before implementing fixes
2. **Incremental**: Fix one category at a time to avoid regressions
3. **Validated**: Each fix must pass both new and existing test suites
4. **Performance Aware**: Monitor performance impact of each change

### Timeline Estimate

- **Phase 1 (Analysis)**: 2-3 days
- **Phase 2 (Positional)**: 3-4 days
- **Phase 3 (Language Features)**: 5-7 days
- **Phase 4 (Type System)**: 3-4 days
- **Phase 5 (CSS/DOM)**: 4-5 days
- **Phase 6 (Missing Features)**: 7-10 days
- **Phase 7 (Error Handling)**: 3-4 days
- **Phase 8 (Validation)**: 2-3 days

**Total Estimated Effort**: 28-40 days

### Risk Mitigation

- **Regression Prevention**: Comprehensive test suite runs after each change
- **Performance Monitoring**: Benchmark tests included in CI
- **Compatibility Tracking**: Automated monitoring of compatibility scores
- **Rollback Strategy**: Git-based feature branches for safe experimentation

### Success Metrics

- **Test Pass Rate**: 1464/1464 (100%)
- **Official Pattern Compatibility**: 20/20 (100%)
- **Advanced Pattern Compatibility**: 27/27 (100%)
- **Performance**: Maintain <10ms average evaluation
- **Bundle Size**: Stay within 5% of current size

---

## Resources and Tools

### Automated Tools Available

```bash
npm run compatibility:cycle     # Full automated improvement cycle
npm run compatibility:monitor   # Track progress toward 100%
npm run compatibility:dashboard # Visual progress monitoring
npm test src/expressions/       # Run full expression test suite
```

### Documentation References

- **Official \_hyperscript**: https://hyperscript.org/expressions/
- **Current Compatibility Report**: `COMPATIBILITY_REPORT.md`
- **Test Coverage**: `src/expressions/**/*.test.ts`
- **Performance Benchmarks**: `src/performance/expression-benchmarks.test.ts`

### Development Guidelines

- **Maintain backward compatibility**: No breaking changes to existing API
- **Preserve performance**: No regression in speed or memory usage
- **Comprehensive testing**: Every fix must include tests
- **Documentation**: Update compatibility reports as progress is made

---

**🎯 Objective**: Transform LokaScript from 96.3% to 100% \_hyperscript expression compatibility while maintaining world-class performance and reliability.

**🏆 Success Definition**: All 1464 expression tests passing with maintained performance characteristics and complete feature parity with official \_hyperscript expressions.
