# Eval Drift — Guardrails and Fix Pattern
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> - [**RAG** — retrieval-augmented generation and knowledge grounding](./README.md)
> - [**WFGY Global Fix Map** — main Emergency Room, 300+ structured fixes](../README.md)
> - [**WFGY Problem Map 1.0** — 16 reproducible failure modes](../../README.md)
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When evaluation metrics **swing unpredictably** across runs (precision, recall, ΔS, coverage) even though the data and index appear unchanged.
This signals **eval drift**: your evaluation harness is not structurally stable.
---
## Open these first
- Recovery overview: [RAG Architecture & Recovery](https://github.com/onestardao/WFGY/blob/main/ProblemMap/rag-architecture-and-recovery.md)
- Retrieval knobs: [Retrieval Playbook](https://github.com/onestardao/WFGY/blob/main/ProblemMap/retrieval-playbook.md)
- Eval acceptance rules: [Eval — Quality & Readiness Gates](https://github.com/onestardao/WFGY/blob/main/ProblemMap/eval/README.md)
- Precision & recall contract: [Eval RAG Precision/Recall](https://github.com/onestardao/WFGY/blob/main/ProblemMap/eval/eval_rag_precision_recall.md)
- Ordering control: [Bootstrap Ordering](https://github.com/onestardao/WFGY/blob/main/ProblemMap/bootstrap-ordering.md)
- Pre-deploy safety: [Predeploy Collapse](https://github.com/onestardao/WFGY/blob/main/ProblemMap/predeploy-collapse.md)
---
## Core acceptance
- ΔS(question, retrieved) ≤ 0.45 across 3 paraphrases
- Coverage ≥ 0.70 per target section
- λ convergent on 2 seeds, stable across runs
- Variance of metrics ≤ 0.05 across replays
---
## Typical symptoms → exact fix
| Symptom | Likely cause | Open this |
|---------|--------------|-----------|
| Precision/recall varies ±0.20 each run | eval harness non-deterministic | [Eval Precision/Recall](https://github.com/onestardao/WFGY/blob/main/ProblemMap/eval/eval_rag_precision_recall.md) |
| Identical queries give different metrics | bootstrap not fenced | [Bootstrap Ordering](https://github.com/onestardao/WFGY/blob/main/ProblemMap/bootstrap-ordering.md) |
| Eval metrics collapse on fresh deploy | index not fully warmed | [Predeploy Collapse](https://github.com/onestardao/WFGY/blob/main/ProblemMap/predeploy-collapse.md) |
| Coverage < 0.50 despite gold answers | embedding or chunk drift | [Embedding ≠ Semantic](https://github.com/onestardao/WFGY/blob/main/ProblemMap/embedding-vs-semantic.md), [Chunking Checklist](https://github.com/onestardao/WFGY/blob/main/ProblemMap/chunking-checklist.md) |
---
## Fix in 60 seconds
1. **Lock seeds**
Fix random seeds at retrieval, reranker, and eval harness layers.
2. **Fence bootstrap**
Require `VECTOR_READY==true` and index hash match before eval begins.
3. **Replay 3 paraphrases**
Eval the same question with 3 paraphrases. Require ΔS variance < 0.05.
4. **Cross-seed check**
Run two seeds. λ must remain convergent across both.
5. **Regression gate**
Ship only if coverage ≥ 0.70 and precision/recall stable within 0.05.
---
## Copy-paste eval harness snippet
```python
def eval_guardrails(question, retrieved, gold):
ds_qr = deltaS(question, retrieved)
ds_rg = deltaS(retrieved, gold)
assert ds_qr <= 0.45, "ΔS drift detected"
assert coverage(retrieved, gold) >= 0.70, "Coverage too low"
assert lambda_state(retrieved) in {"→","←","<>"} , "λ divergent"
return {
"ΔS_qr": ds_qr,
"ΔS_rg": ds_rg,
"coverage": coverage(retrieved, gold),
"λ": lambda_state(retrieved)
}
````
---
## Diagnostic probes
* **Re-run variance test**: run eval 5 times, log precision/recall. Stddev >0.05 → unstable harness.
* **Anchor comparison**: compare ΔS to gold anchor vs decoy. If both similar, re-embed.
* **Deploy warm-up**: log `VECTOR_READY` and index hash before eval.
---
### 🔗 Quick-Start Downloads (60 sec)
| Tool | Link | 3-Step Setup |
| -------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------- |
| **WFGY 1.0 PDF** | [Engine Paper](https://github.com/onestardao/WFGY/blob/main/I_am_not_lizardman/WFGY_All_Principles_Return_to_One_v1.0_PSBigBig_Public.pdf) | 1️⃣ Download · 2️⃣ Upload to your LLM · 3️⃣ Ask “Answer using WFGY + ” |
| **TXT OS (plain-text OS)** | [TXTOS.txt](https://github.com/onestardao/WFGY/blob/main/OS/TXTOS.txt) | 1️⃣ Download · 2️⃣ Paste into any LLM chat · 3️⃣ Type “hello world” — OS boots instantly |
---
### 🧭 Explore More
| Module | Description | Link |
| ------------------------ | ---------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------- |
| WFGY Core | WFGY 2.0 engine is live: full symbolic reasoning architecture and math stack | [View →](https://github.com/onestardao/WFGY/tree/main/core/README.md) |
| Problem Map 1.0 | Initial 16-mode diagnostic and symbolic fix framework | [View →](https://github.com/onestardao/WFGY/tree/main/ProblemMap/README.md) |
| Problem Map 2.0 | RAG-focused failure tree, modular fixes, and pipelines | [View →](https://github.com/onestardao/WFGY/blob/main/ProblemMap/rag-architecture-and-recovery.md) |
| Semantic Clinic Index | Expanded failure catalog: prompt injection, memory bugs, logic drift | [View →](https://github.com/onestardao/WFGY/blob/main/ProblemMap/SemanticClinicIndex.md) |
| Semantic Blueprint | Layer-based symbolic reasoning & semantic modulations | [View →](https://github.com/onestardao/WFGY/tree/main/SemanticBlueprint/README.md) |
| Benchmark vs GPT-5 | Stress test GPT-5 with full WFGY reasoning suite | [View →](https://github.com/onestardao/WFGY/tree/main/benchmarks/benchmark-vs-gpt5/README.md) |
| 🧙♂️ Starter Village 🏡 | New here? Lost in symbols? Click here and let the wizard guide you through | [Start →](https://github.com/onestardao/WFGY/blob/main/StarterVillage/README.md) |
---
> 👑 **Early Stargazers: [See the Hall of Fame](https://github.com/onestardao/WFGY/tree/main/stargazers)**
> ⭐ [WFGY Engine 2.0](https://github.com/onestardao/WFGY/blob/main/core/README.md) is already unlocked. ⭐
[](https://github.com/onestardao/WFGY)
[](https://github.com/onestardao/WFGY/tree/main/OS)
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