Layer 4 complete. 449 tests, 0 failures, 36 excluded

Author: NSHkr

LAYER3_QUAD.md

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+# Product Requirements Document (PRD): Layer 4 - JSON Validation
+
+## Document Information
+- **Product**: JsonRemedy Layer 4 - JSON Validation
+- **Version**: 1.0
+- **Date**: January 2025
+- **Status**: Draft
+- **Owner**: JsonRemedy Development Team
+
+## Executive Summary
+
+Layer 4 (JSON Validation) serves as the "fast path" validation layer in the JsonRemedy pipeline, providing high-performance JSON parsing for content that has been successfully repaired by previous layers or was already valid. This layer leverages the Jason library to attempt standard JSON parsing and either returns parsed results or passes malformed content to subsequent layers for more aggressive processing.
+
+## Product Overview
+
+### Purpose
+Layer 4 acts as a performance optimization checkpoint that:
+- Validates JSON syntax using industry-standard parsing (Jason)
+- Provides immediate results for valid JSON (fast path)
+- Efficiently identifies content requiring further processing
+- Maintains pipeline integrity through proper error handling
+
+### Position in Pipeline
+```
+Layer 1 → Layer 2 → Layer 3 → Layer 4 → Layer 5
+Content   Structural  Syntax     JSON      Tolerant
+Cleaning   Repair     Normal.    Validation Parsing
+```
+
+Layer 4 receives input from Layer 3 (Syntax Normalization) and either:
+- **Success Path**: Returns parsed JSON to the pipeline caller
+- **Continue Path**: Passes malformed content to Layer 5 (Tolerant Parsing)
+
+## Goals and Objectives
+
+### Primary Goals
+1. **Performance Optimization**: Provide fast parsing for valid JSON content
+2. **Standard Compliance**: Ensure RFC 7159/ECMA-404 JSON compliance validation
+3. **Pipeline Efficiency**: Minimize processing overhead for already-valid content
+4. **Error Classification**: Accurately identify content requiring further processing
+
+### Success Metrics
+- **Performance**: Valid JSON parsing < 100μs for inputs under 10KB
+- **Accuracy**: 100% compliance with JSON standards
+- **Throughput**: Handle 1000+ validations/second under load
+- **Memory**: < 2x input size memory overhead during parsing
+
+## Target Users
+
+### Primary Users
+- **JsonRemedy Pipeline**: Automated processing system
+- **API Developers**: Processing external JSON responses
+- **Configuration Systems**: Validating config files
+- **Data Processing Pipelines**: Handling JSON data streams
+
+### Use Cases
+1. **Clean JSON Processing**: Fast path for already-valid JSON
+2. **Repaired Content Validation**: Validating output from previous layers
+3. **Quality Gate**: Ensuring JSON compliance before final output
+4. **Performance Critical Paths**: High-throughput JSON validation
+
+## Functional Requirements
+
+### Core Functionality
+
+#### FR-001: Jason Integration
+- **Requirement**: Integrate Jason library for JSON parsing
+- **Details**: 
+  - Use Jason.decode/2 for parsing operations
+  - Configure appropriate decode options
+  - Handle all Jason error types gracefully
+- **Priority**: P0 (Critical)
+
+#### FR-002: Fast Path Processing
+- **Requirement**: Provide optimized parsing for valid JSON
+- **Details**:
+  - Attempt Jason parsing first
+  - Return parsed Elixir terms on success
+  - Complete within performance thresholds
+- **Priority**: P0 (Critical)
+
+#### FR-003: Pass-Through Behavior
+- **Requirement**: Pass malformed JSON to next layer
+- **Details**:
+  - Return `{:continue, input, context}` for parse failures
+  - Preserve input string exactly
+  - Maintain all context information
+- **Priority**: P0 (Critical)
+
+#### FR-004: Context Preservation
+- **Requirement**: Maintain repair context from previous layers
+- **Details**:
+  - Preserve existing repairs list
+  - Maintain options and metadata
+  - Update layer processing status
+- **Priority**: P0 (Critical)
+
+### Input/Output Specifications
+
+#### Input Requirements
+- **Type**: String (binary)
+- **Format**: Potentially valid JSON or malformed content
+- **Size**: Up to 100MB (configurable)
+- **Encoding**: UTF-8
+
+#### Output Specifications
+- **Success**: `{:ok, parsed_json, updated_context}`
+- **Continue**: `{:continue, input_string, preserved_context}`
+- **Error**: `{:error, error_reason}` (rare, only for system failures)
+
+### Error Handling
+
+#### EH-001: Jason Decode Errors
+- **Requirement**: Handle all Jason.DecodeError cases
+- **Behavior**: Convert to continue result, preserve input
+- **Examples**: Syntax errors, invalid escapes, truncated JSON
+
+#### EH-002: System Errors
+- **Requirement**: Handle unexpected system failures
+- **Behavior**: Return error tuple with descriptive message
+- **Examples**: Memory exhaustion, timeout conditions
+
+#### EH-003: Input Validation
+- **Requirement**: Validate input parameters
+- **Behavior**: Handle nil, non-string, oversized inputs gracefully
+
+## Non-Functional Requirements
+
+### Performance Requirements
+
+#### NFR-001: Parsing Speed
+- **Requirement**: Valid JSON parsing performance targets
+- **Metrics**:
+  - < 10μs for simple JSON (< 1KB)
+  - < 100μs for medium JSON (1KB - 10KB)
+  - < 1ms for large JSON (10KB - 100KB)
+- **Priority**: P0 (Critical)
+
+#### NFR-002: Memory Efficiency
+- **Requirement**: Minimize memory overhead
+- **Metrics**:
+  - < 2x input size peak memory usage
+  - No memory leaks on repeated calls
+  - Efficient garbage collection
+- **Priority**: P1 (High)
+
+#### NFR-003: Throughput
+- **Requirement**: Support high-volume processing
+- **Metrics**:
+  - 1000+ validations/second sustained
+  - Linear scaling with CPU cores
+  - Minimal resource contention
+- **Priority**: P1 (High)
+
+### Reliability Requirements
+
+#### NFR-004: Error Recovery
+- **Requirement**: Graceful handling of all error conditions
+- **Metrics**:
+  - No crashes on malformed input
+  - Proper error classification
+  - Consistent behavior under stress
+- **Priority**: P0 (Critical)
+
+#### NFR-005: Thread Safety
+- **Requirement**: Safe concurrent usage
+- **Metrics**:
+  - No shared mutable state
+  - Race condition prevention
+  - Deterministic results
+- **Priority**: P0 (Critical)
+
+### Security Requirements
+
+#### NFR-006: Input Safety
+- **Requirement**: Safe processing of untrusted input
+- **Details**:
+  - Prevent JSON bomb attacks
+  - Input size limits
+  - Memory usage controls
+- **Priority**: P1 (High)
+
+## Technical Specifications
+
+### Architecture Design
+
+#### Layer Integration
+```elixir
+@behaviour JsonRemedy.LayerBehaviour
+
+@impl true
+def process(input, context) do
+  case Jason.decode(input) do
+    {:ok, parsed} -> 
+      {:ok, parsed, update_context(context)}
+    {:error, _jason_error} -> 
+      {:continue, input, context}
+  end
+rescue
+  error -> {:error, format_error(error)}
+end
+```
+
+#### Configuration Options
+- `:jason_options` - Options passed to Jason.decode/2
+- `:fast_path_optimization` - Enable/disable optimizations
+- `:validate_encoding` - UTF-8 validation before parsing
+- `:timeout_ms` - Maximum parsing time
+- `:max_input_size` - Input size limits
+
+#### Dependencies
+- **Jason**: Primary JSON parsing library
+- **JsonRemedy.LayerBehaviour**: Interface compliance
+- **String**: UTF-8 validation utilities
+
+### Data Structures
+
+#### Repair Context
+```elixir
+%{
+  repairs: [repair_action()],
+  options: keyword(),
+  metadata: %{
+    layer4_processed: boolean(),
+    validation_time_us: non_neg_integer(),
+    parsed_successfully: boolean()
+  }
+}
+```
+
+#### Layer Result
+```elixir
+{:ok, json_value(), repair_context()} |
+{:continue, String.t(), repair_context()} |
+{:error, String.t()}
+```
+
+## Implementation Plan
+
+### Phase 1: Core Implementation (Week 1)
+- [ ] Basic Jason integration
+- [ ] LayerBehaviour implementation
+- [ ] Core process/2 function
+- [ ] Basic error handling
+
+### Phase 2: Optimization (Week 2)
+- [ ] Performance optimizations
+- [ ] Configuration system
+- [ ] Memory efficiency improvements
+- [ ] Concurrent access safety
+
+### Phase 3: Testing & Validation (Week 3)
+- [ ] Comprehensive test suite (40+ tests)
+- [ ] Performance benchmarks
+- [ ] Security testing
+- [ ] Integration testing
+
+### Phase 4: Documentation & Polish (Week 4)
+- [ ] API documentation
+- [ ] Usage examples
+- [ ] Performance guide
+- [ ] Error handling guide
+
+## Testing Strategy
+
+### Unit Testing
+- **Coverage Target**: 95%+ line coverage
+- **Test Categories**: Basic validation, error handling, edge cases
+- **Performance Tests**: Timing and memory validation
+- **Security Tests**: Malicious input handling
+
+### Integration Testing
+- **Pipeline Integration**: Test with all other layers
+- **Real-world Data**: Test with actual JSON from various sources
+- **Stress Testing**: High-volume concurrent processing
+
+### Property-Based Testing
+- **JSON Invariants**: Valid JSON always parses
+- **Performance Properties**: Timing characteristics
+- **Memory Properties**: No leaks or excessive usage
+
+## Quality Assurance
+
+### Acceptance Criteria
+1. **Functional**: All 40 essential test cases pass
+2. **Performance**: Meets all NFR timing requirements
+3. **Reliability**: Zero crashes on malformed input
+4. **Integration**: Seamless pipeline operation
+
+### Quality Gates
+- **Code Review**: All code reviewed by 2+ developers
+- **Performance Review**: Benchmarks meet requirements
+- **Security Review**: Input safety validation
+- **Documentation Review**: Complete and accurate docs
+
+## Risk Assessment
+
+### Technical Risks
+| Risk | Impact | Probability | Mitigation |
+|------|--------|-------------|------------|
+| Jason dependency issues | High | Low | Pin version, test compatibility |
+| Memory leaks in parsing | Medium | Medium | Comprehensive memory testing |
+| Performance regressions | High | Medium | Continuous benchmarking |
+| Unicode handling issues | Medium | Low | Extensive UTF-8 testing |
+
+### Operational Risks
+| Risk | Impact | Probability | Mitigation |
+|------|--------|-------------|------------|
+| Breaking API changes | High | Low | Semantic versioning, deprecation |
+| Integration failures | Medium | Medium | Comprehensive integration tests |
+| Production performance | Medium | Low | Load testing, monitoring |
+
+## Success Criteria
+
+### Definition of Done
+- [ ] All functional requirements implemented
+- [ ] All non-functional requirements met
+- [ ] 40+ essential tests passing
+- [ ] Performance benchmarks satisfied
+- [ ] Documentation complete
+- [ ] Security review passed
+
+### Launch Criteria
+- [ ] Integration tests with full pipeline pass
+- [ ] Performance meets production requirements
+- [ ] Error handling robustness validated
+- [ ] Code review and approval complete
+
+## Future Considerations
+
+### Potential Enhancements
+1. **Custom Validation Rules**: Extend beyond basic JSON syntax
+2. **Schema Validation**: JSON Schema compliance checking
+3. **Streaming Support**: Large file processing optimization
+4. **Caching**: Result caching for repeated inputs
+
+### Maintenance Requirements
+- **Dependency Updates**: Regular Jason version updates
+- **Performance Monitoring**: Ongoing benchmark tracking
+- **Security Updates**: Address any discovered vulnerabilities
+- **Documentation Updates**: Keep current with changes
+
+## Appendices
+
+### Appendix A: Jason Library Integration
+- Configuration options mapping
+- Error type handling matrix
+- Performance optimization settings
+
+### Appendix B: Performance Benchmarks
+- Target timing specifications
+- Memory usage profiles
+- Concurrent processing metrics
+
+### Appendix C: Security Considerations
+- Input validation strategies
+- Attack vector prevention
+- Resource limit enforcement
+
+---
+
+**Document Approval**
+- [ ] Technical Lead Review
+- [ ] Architecture Review
+- [ ] Security Review
+- [ ] Product Owner Approval
+
+**Last Updated**: January 2025  
+**Next Review Date**: February 2025