fable-agent/PHASES/phase-06-convergence-check.md

Phase 6: Convergence Check

Purpose: The loop doesn't run forever. It runs until it converges. TS Module: src/tier2-primitives/loops/convergence-check.ts

What It Does

Detects when to stop the loop:

1. Max iterations reached → hard stop
2. Diminishing returns → improvement delta below threshold for N iterations
3. Quality plateau → quality score flat for N iterations and already acceptable
4. Target achieved → quality and success rate both above 0.95

Signals

Signal	Meaning	Action
continuing	Loop should keep running	Let it run
diminishing_returns	Delta below threshold	Exit — more iterations won't help
quality_plateau	Quality flat and acceptable	Exit with current state
target_achieved	Quality > 0.95 and success > 0.95	Exit — goal fully met

Key Rules

• Set convergenceThreshold based on task difficulty (0.05 for standard, 0.02 for precise)
• In the rubric engine, convergence is replaced by rubric-guided exit conditions
• A plateau with low quality signals "restart approach" — not "exit successful"