[SESSION_127] ConfigAgent: Implement Node Reordering Optimizer (Phase 23)

Feature: Node Reordering Optimization

Component: ConfigAgent (/agents/config_agent/)
Severity: 🔴 CRITICAL BLOCKER
Session: SESSION 127 (Definition of Done)
Current Status: Returns empty recommendations list
Target Phase: Phase 23

Context

Pipeline DAG optimization is a high-value recommendation for throughput improvement. ConfigAgent currently returns empty recommendations for node reordering, missing major performance gains.

Requirements

• Analyze pipeline DAG structure
• Calculate node execution cost (latency, CPU/GPU)
• Detect suboptimal orderings
• Generate reordering recommendations with expected improvement
• Verify topological validity after reordering

Impact

Without this feature:

• Cannot optimize pipeline order
• Lost throughput gains (5-20% typical)
• Users deploy suboptimal pipelines

Effort Estimate

• Topological sort implementation: 4-6 hours
• Cost analysis engine: 6-8 hours
• Testing: 3-4 hours
• Total: 15-20 hours

Technical Approach

• Pipeline DAG analysis (node dependencies)
• Critical path analysis
• Cost-benefit calculation per reordering
• Recommendation ranking by expected improvement

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Generated by SESSION 127 FASE 2.7