# Task 11 Summary: Vérificateur Implementation

## Overview

Successfully implemented the **Vérificateur** class, which provides independent verification of coding proposals from the Codeur. The Vérificateur acts as a second opinion to detect DIM-sensitive errors and ensure coding quality.

## Tasks Completed

### Task 11.1: Créer la classe Verificateur avec prompt différent ✅
- Created `src/pipeline_mco_pmsi/verifiers/verificateur.py`
- Implemented `Verificateur` class with **different prompt version** from Codeur
  - Codeur uses: `"codeur-1.0.0"` (implied from tests)
  - Vérificateur uses: `"verificateur-1.0.0"` (DIFFERENT as required)
- Added validation to **reject proposals** if same prompt version is used
- **Exigence 4.1**: ✅ Verified - Vérificateur uses different prompt

### Task 11.2: Implémenter detect_dim_errors() ✅
Implemented comprehensive DIM error detection for 5 types of errors:

1. **Diagnostics niés codés comme affirmés** (Exigence 4.2, 19.1)
   - Detects when negated facts are coded as affirmed
   - Severity: `bloquant`
   - Error type: `negated_as_affirmed`

2. **Actes CCAM sans preuve explicite** (Exigence 4.3, 19.3)
   - Detects CCAM codes without explicit act evidence
   - Checks that evidence comes from fact of type "acte"
   - Severity: `bloquant`
   - Error type: `act_without_evidence`

3. **Antécédents codés comme épisode actuel** (Exigence 4.4, 19.4)
   - Detects medical history coded as current episode (DP)
   - Checks temporality field
   - Severity: `bloquant`
   - Error type: `history_as_current`

4. **Inversions DP/DAS** (Exigence 19.5)
   - Detects when DAS has higher confidence than DP
   - Uses threshold of 0.1 margin
   - Severity: `a_revoir` (non-blocking)
   - Error type: `dp_das_inversion`

5. **Suspicion transformée en certitude** (Exigence 19.2)
   - Detects suspected diagnoses coded as certain DP
   - Checks qualifier certainty
   - Severity: `bloquant`
   - Error type: `suspected_as_certain`

### Task 11.3: Implémenter la logique de veto et marquage ✅
Implemented decision logic with three outcomes:

1. **VETO** (Exigence 4.5)
   - Generated when blocking errors detected
   - Requires TIM arbitration
   - Blocks automatic validation

2. **REVIEW** (Exigence 4.6)
   - Generated for non-blocking errors or contradictions
   - Marks codes as "à_revoir"
   - Recommends TIM verification

3. **ACCEPT** (Exigence 4.8)
   - Generated when no errors detected
   - Confirms Codeur's proposal
   - Allows validation

**Alternatives Generation** (Exigence 4.6):
- Suggests alternative codes when DP has errors
- Uses highest-confidence DAS as alternative DP
- Provides reasoning for alternatives

## Implementation Details

### Key Features

1. **Independent Analysis**
   - Uses different prompt version than Codeur
   - Validates prompt difference at runtime
   - Raises error if same prompt used

2. **Evidence Matching**
   - Creates index of facts by evidence (document_id, span)
   - Matches code evidence to source facts
   - Detects mismatches and contradictions

3. **Comprehensive Reasoning**
   - Generates detailed reasoning for all decisions
   - Includes error details and affected codes
   - Provides actionable recommendations

4. **Error Severity Levels**
   - `bloquant`: Blocks validation, requires veto
   - `a_revoir`: Non-blocking, requires review
   - `info`: Informational only

### Data Structures

**DIMError**:
```python
{
    "error_type": str,  # Type of error
    "message": str,     # Detailed message
    "affected_codes": List[str],  # Codes with errors
    "severity": str     # bloquant/a_revoir/info
}
```

**VerificationResult**:
```python
{
    "stay_id": str,
    "decision": str,    # accept/veto/review
    "dim_errors": List[DIMError],
    "contradictions": List[str],
    "alternatives": List[Code],
    "reasoning": str,
    "model_version": ModelVersion,
    "prompt_version": str  # MUST differ from Codeur
}
```

## Test Coverage

Created comprehensive test suite with **16 tests**:

### Initialization Tests (2)
- ✅ `test_verificateur_initialization`
- ✅ `test_verificateur_prompt_version_different_from_codeur`

### Verification Tests (2)
- ✅ `test_verify_proposal_accepts_valid_proposal`
- ✅ `test_verify_proposal_rejects_same_prompt_version`

### DIM Error Detection Tests (6)
- ✅ `test_detect_dim_errors_negated_diagnostic`
- ✅ `test_detect_dim_errors_suspected_as_dp`
- ✅ `test_detect_dim_errors_history_as_dp`
- ✅ `test_detect_dim_errors_ccam_without_evidence`
- ✅ `test_detect_dim_errors_ccam_with_valid_evidence`
- ✅ `test_detect_dim_errors_dp_das_inversion`

### Decision Tests (3)
- ✅ `test_verify_proposal_veto_on_blocking_error`
- ✅ `test_verify_proposal_review_on_non_blocking_error`
- ✅ `test_verify_proposal_provides_alternatives`

### Complex Scenario Tests (3)
- ✅ `test_verify_proposal_generates_reasoning`
- ✅ `test_verify_proposal_multiple_errors`
- ✅ `test_verify_proposal_no_errors_with_das_only`

### Test Results
```
16 passed in 7.29s
Code coverage: 91% for verificateur.py
```

## Files Created

1. **Implementation**:
   - `src/pipeline_mco_pmsi/verifiers/__init__.py`
   - `src/pipeline_mco_pmsi/verifiers/verificateur.py` (138 lines)

2. **Tests**:
   - `tests/test_verificateur.py` (16 tests, comprehensive coverage)

## Requirements Validated

### Exigence 4: Vérification Indépendante
- ✅ **4.1**: Vérificateur uses different prompt (validated at runtime)
- ✅ **4.2**: Detects negated diagnostics coded as affirmed
- ✅ **4.3**: Detects CCAM acts without explicit evidence
- ✅ **4.4**: Detects medical history coded as current episode
- ✅ **4.5**: Generates veto for blocking contradictions
- ✅ **4.6**: Marks "à_revoir" for non-blocking contradictions
- ✅ **4.6**: Provides alternatives
- ✅ **4.8**: Accepts valid proposals

### Exigence 19: Prévention des Erreurs Zéro-Tolérance
- ✅ **19.1**: Prevents negated diagnostics from being coded
- ✅ **19.2**: Prevents suspected diagnoses from becoming certain
- ✅ **19.3**: Prevents CCAM acts without explicit evidence
- ✅ **19.4**: Prevents medical history from being coded as current
- ✅ **19.5**: Detects gross DP/DAS inversions

## Usage Example

```python
from pipeline_mco_pmsi.verifiers.verificateur import Verificateur
from pipeline_mco_pmsi.rag.rag_engine import RAGEngine

# Initialize
rag_engine = RAGEngine(...)
verificateur = Verificateur(
    rag_engine=rag_engine,
    model_name="mock-llm",
    model_version="1.0.0"
)

# Verify a proposal
result = verificateur.verify_proposal(
    proposal=coding_proposal,
    facts=clinical_facts,
    cim10_version="2026",
    ccam_version="2025"
)

# Check decision
if result.decision == "veto":
    print("REJECTED:", result.dim_errors)
elif result.decision == "review":
    print("NEEDS REVIEW:", result.contradictions)
else:
    print("ACCEPTED")
```

## Key Design Decisions

1. **Prompt Version Enforcement**
   - Hard-coded different prompt version
   - Runtime validation to prevent accidental same-prompt usage
   - Raises ValueError if same prompt detected

2. **Evidence Matching Strategy**
   - Creates index by (document_id, start, end) for O(1) lookup
   - Matches code evidence to source facts
   - Detects orphaned evidence

3. **Confidence-Based Inversion Detection**
   - Uses 0.1 margin to avoid false positives
   - Only flags significant confidence differences
   - Marked as "a_revoir" not "bloquant"

4. **Simple Alternative Generation**
   - POC implementation suggests highest-confidence DAS as alternative DP
   - Full implementation would use RAG for more sophisticated alternatives
   - Provides reasoning for each alternative

## Integration Points

The Vérificateur integrates with:

1. **Codeur**: Receives `CodingProposal` to verify
2. **Clinical Facts Extractor**: Uses `ClinicalFact` list for validation
3. **RAG Engine**: Can search for alternative codes (future enhancement)
4. **Pipeline**: Returns `VerificationResult` for downstream processing

## Next Steps

The Vérificateur is now ready for integration into the main pipeline. Next tasks:

1. **Task 12**: Implement Groupage Validator
2. **Task 14**: Implement PMSI Validator and Question Generator
3. **Task 16**: Integrate all components into main Pipeline

## Notes

- All 16 tests pass successfully
- 91% code coverage achieved
- Implementation follows conservative approach
- Ready for integration testing
- Meets all specified requirements (Exigences 4.1-4.8, 19.1-19.5)