Architecture analysis: Identify coupling issues and refactoring opportunities

[Copilot]

Comprehensive architectural review of Primus training framework to identify tight coupling, abstraction leaks, and incremental refactoring opportunities.

Deliverables

ARCHITECTURE_ANALYSIS.md - Full technical analysis (710 lines)

• Current architecture: 6 core + 4 backend + 3 supporting subsystems
• Top 5 pain points with file paths and severity ratings
• 5 incremental refactoring suggestions (≤2 files each)

ARCHITECTURE_SUMMARY.txt - Executive summary for quick scanning

Key Findings

Overall: Solid plugin architecture with clean backend isolation. Minor fixable issues.

Top 5 Pain Points

1. 🔴 HIGH: Backend-specific logic in core layer

   • primus/core/trainer/base_trainer.py:92-97 hardcodes Megatron global vars
   • Violates abstraction boundary

2. 🔴 HIGH: Legacy config parser coupling

   • primus/core/config/primus_config.py depends on "legacy" PrimusParser
   • Blocks config system evolution

3. ⚠️ MEDIUM: Scattered patch application

   • 3 different entry points (BaseTrainer, BackendAdapter, MegatronBaseTrainer)
   • Unclear execution order

4. ⚠️ MEDIUM: Silent config merging

   • backend_adapter.py:238-249 overwrites without warnings
   • Hard to debug conflicts

5. ⚠️ LOW: Late version detection

   • Backend version unavailable during setup patches
   • Limits flexibility

Refactoring Suggestions

All maintain backward compatibility and touch ≤2 files:

1. Extract backend initialization hook → removes Megatron hardcoding
2. Introduce ConfigLoader interface → decouples from legacy parser
3. Centralize patch application → single source of truth
4. Add config merge validation → detect conflicts
5. Early version detection → enable version-aware setup patches

Architecture Strengths

• Clean backend adapter abstraction (Strategy pattern)
• Plugin registry with lazy loading
• Version-aware patch system
• Zero cross-backend dependencies
• Template method for consistent workflows

No code changes made - analysis only.

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