Summary

Create a comprehensive feature parity matrix documenting which C++ features are available in each Rust port, their implementation status, and API differences.

Parent Issue

Part of: [EPIC] docs: Address documentation gaps across all ecosystem systems (#325)

Background (Why)

The kcenon ecosystem has parallel Rust implementations for several systems:

• rust_thread_system — Thread pool and job scheduling
• rust_logger_system — Logging (23 .rs files)
• rust_monitoring_system — Monitoring and metrics
• rust_database_system — Database access (SQLite only)
• rust_network_system — Networking
• rust_container_system — Container types
• rust_integrated_thread_system — Integrated thread system

Users choosing between C++ and Rust versions need to know which features are available, missing, or different. No such comparison exists.

Scope (What)

Create docs/RUST_PARITY.md covering:

1. Overall Parity Status

2. Per-System Feature Comparison

For each system, create a detailed table:

#### thread_system
| Feature | C++ | Rust | Notes |
|---------|-----|------|-------|
| Basic thread pool | ✅ | ✅ | API differs |
| Policy queues | ✅ | ❌ | Not ported |
| NUMA support | ✅ | ❌ | Not ported |
| Autoscaler | ✅ | ✅ | Simplified |
| DAG scheduler | ✅ | ❌ | Not ported |
| Diagnostics | ✅ | ❌ | Not ported |

3. API Mapping Guide

• Naming convention differences (C++ snake_case vs Rust snake_case)
• Type mapping (std::string ↔ String, Result ↔ Result<T, E>)
• Error handling differences (C++ Result vs Rust std::result::Result)
• Memory management (C++ RAII vs Rust ownership)

4. Interop Considerations

• FFI boundaries (if any)
• Data format compatibility
• Protocol compatibility for network communication
• Shared configuration format

5. Roadmap

• Planned Rust features per system
• Priority of feature ports
• Timeline estimates (if available)

Acceptance Criteria

• Parity matrix for all 7 systems with C++ and Rust versions
• Per-system feature comparison tables
• API mapping guide for common patterns
• Interop considerations documented
• Current status accurately reflects source code
• Updated as Rust ports evolve (living document)