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+# ADR-CE-021: Shared SONA
+
+**Status**: Accepted
+**Date**: 2026-01-22
+**Parent**: ADR-014 Coherence Engine Architecture
+
+## Context
+
+Both RuvLLM and Prime-Radiant use SONA for adaptive tuning:
+- RuvLLM: Quality thresholds, routing weights
+- Prime-Radiant: Coherence thresholds, escalation triggers
+
+Running two SONA instances wastes resources and may learn conflicting adaptations.
+
+## Decision
+
+**SonaIntegration shared between ruvllm and Prime-Radiant.**
+
+Shared components:
+- `SonaEngine`: Single instance with multiple learning targets
+- `ReasoningBank`: Unified pattern storage
+- `EWC++`: Consolidated knowledge across both systems
+
+Configuration:
+```rust
+pub struct SharedSona {
+    engine: SonaEngine,
+    llm_targets: Vec<LlmLearningTarget>,
+    coherence_targets: Vec<CoherenceLearningTarget>,
+}
+```
+
+Learning coordination:
+- Both systems contribute trajectories
+- EWC++ prevents forgetting across domains
+- Patterns accessible to both systems
+
+## Consequences
+
+### Benefits
+- Unified adaptation reduces resource usage
+- Cross-domain learning (LLM patterns help coherence, vice versa)
+- Consistent behavior across systems
+
+### Risks
+- Coupling between systems
+- Bad learning in one domain affects both
+
+## References
+
+- ADR-014: Coherence Engine Architecture, "RuvLLM Integration"
+- sona crate documentation