feat: ajout RAG CIM-10 avec FAISS + Ollama

Implémente un système RAG (Retrieval Augmented Generation) qui indexe
les documents de référence ATIH (CIM-10 FR 2026, Guide Métho MCO,
CCAM PMSI) et utilise Ollama (mistral-small3.2:24b) pour justifier
et valider le codage CIM-10 des diagnostics.

- Nouveaux modèles Pydantic : RAGSource, Diagnostic étendu (confidence,
  justification, sources_rag) — rétrocompatible
- Module rag_index.py : chunking des 3 PDFs, embedding sentence-camembert-large,
  index FAISS IndexFlatIP (3630 vecteurs)
- Module rag_search.py : recherche FAISS + appel Ollama avec fallback double
- Flag CLI --no-rag pour désactiver l'enrichissement RAG
- 18 nouveaux tests (88/88 passent)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_rag.py

@@ -0,0 +1,271 @@
+"""Tests pour le RAG CIM-10 (modèles, chunking, intégration)."""
+
+from __future__ import annotations
+
+from pathlib import Path
+from unittest.mock import patch, MagicMock
+
+import pytest
+
+from src.config import RAGSource, Diagnostic, DossierMedical, CIM10_PDF, GUIDE_METHODO_PDF, CCAM_PDF
+
+
+class TestRAGSource:
+    def test_create_minimal(self):
+        src = RAGSource(document="cim10")
+        assert src.document == "cim10"
+        assert src.page is None
+        assert src.code is None
+        assert src.extrait is None
+
+    def test_create_full(self):
+        src = RAGSource(
+            document="guide_methodo",
+            page=42,
+            code="K85",
+            extrait="Pancréatite aiguë biliaire...",
+        )
+        assert src.document == "guide_methodo"
+        assert src.page == 42
+        assert src.code == "K85"
+        assert src.extrait == "Pancréatite aiguë biliaire..."
+
+    def test_serialization(self):
+        src = RAGSource(document="ccam", page=1, code="HMFC004")
+        data = src.model_dump(exclude_none=True)
+        assert data == {"document": "ccam", "page": 1, "code": "HMFC004"}
+
+
+class TestDiagnosticExtended:
+    def test_backward_compatible(self):
+        """Les nouveaux champs sont optionnels — rétrocompatible."""
+        d = Diagnostic(texte="Pancréatite aiguë", cim10_suggestion="K85.9")
+        assert d.texte == "Pancréatite aiguë"
+        assert d.cim10_suggestion == "K85.9"
+        assert d.cim10_confidence is None
+        assert d.justification is None
+        assert d.sources_rag == []
+
+    def test_with_rag_fields(self):
+        d = Diagnostic(
+            texte="Lithiase cholédoque",
+            cim10_suggestion="K80.5",
+            cim10_confidence="high",
+            justification="Code K80.5 correspond à la lithiase du cholédoque",
+            sources_rag=[
+                RAGSource(document="cim10", page=480, code="K80"),
+            ],
+        )
+        assert d.cim10_confidence == "high"
+        assert d.justification is not None
+        assert len(d.sources_rag) == 1
+        assert d.sources_rag[0].code == "K80"
+
+    def test_serialization_exclude_none(self):
+        """Vérifier que le JSON n'inclut pas les champs None."""
+        d = Diagnostic(texte="Test", cim10_suggestion="K85.9")
+        data = d.model_dump(exclude_none=True)
+        assert "cim10_confidence" not in data
+        assert "justification" not in data
+        assert "sources_rag" in data  # list vide incluse
+
+    def test_dossier_with_extended_diagnostic(self):
+        """Un DossierMedical avec des diagnostics enrichis par le RAG."""
+        dossier = DossierMedical(
+            diagnostic_principal=Diagnostic(
+                texte="Pancréatite aiguë biliaire",
+                cim10_suggestion="K85.1",
+                cim10_confidence="high",
+                justification="Confirmé par CIM-10 FR 2026",
+                sources_rag=[
+                    RAGSource(document="cim10", page=496, code="K85"),
+                    RAGSource(document="guide_methodo", page=30),
+                ],
+            ),
+        )
+        assert dossier.diagnostic_principal.cim10_confidence == "high"
+        assert len(dossier.diagnostic_principal.sources_rag) == 2
+
+
+class TestExtractMedicalInfoRAGFlag:
+    def test_use_rag_false_no_change(self):
+        """use_rag=False ne modifie pas le comportement existant."""
+        from src.medical.cim10_extractor import extract_medical_info
+
+        parsed = {
+            "type": "crh",
+            "patient": {"sexe": "M"},
+            "sejour": {},
+            "diagnostics": [],
+        }
+        text = "Pancréatite aiguë biliaire.\nTTT de sortie :\nParacétamol\n\nDevenir : retour."
+
+        dossier = extract_medical_info(parsed, text, use_rag=False)
+        assert dossier.diagnostic_principal is not None
+        assert dossier.diagnostic_principal.cim10_suggestion == "K85.1"
+        # Pas de sources RAG
+        assert dossier.diagnostic_principal.sources_rag == []
+        assert dossier.diagnostic_principal.justification is None
+
+    def test_use_rag_true_calls_enrich(self):
+        """use_rag=True appelle _enrich_with_rag (mocké)."""
+        from src.medical.cim10_extractor import extract_medical_info
+
+        parsed = {
+            "type": "crh",
+            "patient": {"sexe": "M"},
+            "sejour": {},
+            "diagnostics": [],
+        }
+        text = "Pancréatite aiguë biliaire.\nTTT de sortie :\nParacétamol\n\nDevenir : retour."
+
+        with patch("src.medical.cim10_extractor._enrich_with_rag") as mock_enrich:
+            dossier = extract_medical_info(parsed, text, use_rag=True)
+            mock_enrich.assert_called_once_with(dossier)
+
+    def test_use_rag_default_false(self):
+        """Par défaut, use_rag=False."""
+        from src.medical.cim10_extractor import extract_medical_info
+
+        parsed = {
+            "type": "crh",
+            "patient": {"sexe": "M"},
+            "sejour": {},
+            "diagnostics": [],
+        }
+        text = "Test simple."
+
+        with patch("src.medical.cim10_extractor._enrich_with_rag") as mock_enrich:
+            extract_medical_info(parsed, text)
+            mock_enrich.assert_not_called()
+
+
+class TestChunkingCIM10:
+    @pytest.mark.skipif(
+        not CIM10_PDF.exists(),
+        reason=f"PDF CIM-10 non trouvé : {CIM10_PDF}",
+    )
+    def test_chunks_contain_known_codes(self):
+        from src.medical.rag_index import _chunk_cim10
+
+        chunks = _chunk_cim10(CIM10_PDF)
+        assert len(chunks) > 100, f"Trop peu de chunks : {len(chunks)}"
+
+        codes = {c.code for c in chunks if c.code}
+        assert "K85" in codes, "K85 (pancréatite) non trouvé"
+        assert "K80" in codes, "K80 (lithiase biliaire) non trouvé"
+        assert "E66" in codes, "E66 (obésité) non trouvé"
+
+    @pytest.mark.skipif(
+        not CIM10_PDF.exists(),
+        reason=f"PDF CIM-10 non trouvé : {CIM10_PDF}",
+    )
+    def test_chunk_content(self):
+        from src.medical.rag_index import _chunk_cim10
+
+        chunks = _chunk_cim10(CIM10_PDF)
+        k85_chunks = [c for c in chunks if c.code == "K85"]
+        assert len(k85_chunks) >= 1
+        assert "pancréatite" in k85_chunks[0].text.lower() or "pancreatite" in k85_chunks[0].text.lower()
+
+
+class TestChunkingGuideMethodo:
+    @pytest.mark.skipif(
+        not GUIDE_METHODO_PDF.exists(),
+        reason=f"PDF Guide Métho non trouvé : {GUIDE_METHODO_PDF}",
+    )
+    def test_chunks_extracted(self):
+        from src.medical.rag_index import _chunk_guide_methodo
+
+        chunks = _chunk_guide_methodo(GUIDE_METHODO_PDF)
+        assert len(chunks) >= 10, f"Trop peu de chunks : {len(chunks)}"
+        assert all(c.document == "guide_methodo" for c in chunks)
+
+
+class TestChunkingCCAM:
+    @pytest.mark.skipif(
+        not CCAM_PDF.exists(),
+        reason=f"PDF CCAM non trouvé : {CCAM_PDF}",
+    )
+    def test_chunks_extracted(self):
+        from src.medical.rag_index import _chunk_ccam
+
+        chunks = _chunk_ccam(CCAM_PDF)
+        assert len(chunks) >= 1, f"Aucun chunk CCAM extrait"
+        assert all(c.document == "ccam" for c in chunks)
+
+
+class TestRAGSearchMocked:
+    def test_search_similar_no_index(self):
+        """search_similar retourne une liste vide si l'index n'existe pas."""
+        from src.medical.rag_search import search_similar
+
+        with patch("src.medical.rag_index.get_index", return_value=None):
+            results = search_similar("pancréatite aiguë")
+            assert results == []
+
+    def test_enrich_diagnostic_no_sources(self):
+        """enrich_diagnostic ne plante pas si aucune source trouvée."""
+        from src.medical.rag_search import enrich_diagnostic
+
+        diag = Diagnostic(texte="test quelconque", cim10_suggestion="Z99.9")
+
+        with patch("src.medical.rag_search.search_similar", return_value=[]):
+            enrich_diagnostic(diag, {"sexe": "M", "age": 50})
+
+        assert diag.sources_rag == []
+        assert diag.justification is None
+
+    def test_enrich_diagnostic_with_sources_no_ollama(self):
+        """Enrichissement avec sources FAISS mais sans Ollama."""
+        from src.medical.rag_search import enrich_diagnostic
+
+        diag = Diagnostic(texte="Pancréatite aiguë", cim10_suggestion="K85.9")
+        mock_sources = [
+            {
+                "document": "cim10",
+                "page": 496,
+                "code": "K85",
+                "extrait": "K85 Pancréatite aiguë...",
+                "score": 0.92,
+            },
+        ]
+
+        with patch("src.medical.rag_search.search_similar", return_value=mock_sources), \
+             patch("src.medical.rag_search._call_ollama", return_value=None):
+            enrich_diagnostic(diag, {"sexe": "M", "age": 50})
+
+        assert len(diag.sources_rag) == 1
+        assert diag.sources_rag[0].document == "cim10"
+        assert diag.sources_rag[0].code == "K85"
+        # Pas de justification (Ollama non disponible)
+        assert diag.justification is None
+
+    def test_enrich_diagnostic_with_ollama(self):
+        """Enrichissement complet avec sources + Ollama."""
+        from src.medical.rag_search import enrich_diagnostic
+
+        diag = Diagnostic(texte="Pancréatite aiguë biliaire")
+        mock_sources = [
+            {
+                "document": "cim10",
+                "page": 496,
+                "code": "K85",
+                "extrait": "K85 Pancréatite aiguë...",
+                "score": 0.95,
+            },
+        ]
+        mock_llm = {
+            "code": "K85.1",
+            "confidence": "high",
+            "justification": "Pancréatite aiguë d'origine biliaire = K85.1",
+        }
+
+        with patch("src.medical.rag_search.search_similar", return_value=mock_sources), \
+             patch("src.medical.rag_search._call_ollama", return_value=mock_llm):
+            enrich_diagnostic(diag, {"sexe": "F", "age": 43})
+
+        assert diag.cim10_suggestion == "K85.1"
+        assert diag.cim10_confidence == "high"
+        assert diag.justification == "Pancréatite aiguë d'origine biliaire = K85.1"
+        assert len(diag.sources_rag) == 1