Live AI provider/model switching without restart

Backend:
- RuntimeAIConfig singleton: mutable in-memory overrides for provider/model
- PATCH /admin/api/ai/config: change active provider/model on the fly
- GET /admin/api/ai/config: read current runtime state
- ai_vision.py: uses runtime_ai_config before falling back to settings
- health/status endpoints reflect runtime overrides

Frontend:
- 'Définir comme actif' button in AI config section
- Live feedback message on save

app/main.py

@@ -188,15 +188,20 @@ async def root():
 
 @app.get("/health", tags=["Santé"])
 async def health():
+    from app.services.runtime_config import runtime_ai_config
+    active_provider = runtime_ai_config.provider or settings.AI_PROVIDER
+    active_model = runtime_ai_config.model or (
+        settings.OPENROUTER_MODEL if active_provider == "openrouter"
+        else settings.GEMINI_MODEL
+    )
     ai_configured = (
-        (settings.AI_PROVIDER == "gemini" and bool(settings.GEMINI_API_KEY)) or
-        (settings.AI_PROVIDER == "openrouter" and bool(settings.OPENROUTER_API_KEY))
+        (active_provider == "gemini" and bool(settings.GEMINI_API_KEY)) or
+        (active_provider == "openrouter" and bool(settings.OPENROUTER_API_KEY))
     )
-    active_model = settings.OPENROUTER_MODEL if settings.AI_PROVIDER == "openrouter" else settings.GEMINI_MODEL
     return {
         "status": "healthy",
         "ai_enabled": settings.AI_ENABLED,
-        "ai_provider": settings.AI_PROVIDER,
+        "ai_provider": active_provider,
         "ai_configured": ai_configured,
         "ocr_enabled": settings.OCR_ENABLED,
         "model": active_model,

app/routers/admin_ai.py

@@ -17,6 +17,7 @@ from app.config import settings
 from app.database import get_db
 from app.dependencies.auth import require_scope
 from app.models.client import APIClient
+from app.services.runtime_config import runtime_ai_config
 
 logger = logging.getLogger(__name__)
 
@@ -114,13 +115,14 @@ def _build_providers() -> list[ProviderInfo]:
 @router.get("/status", response_model=AIStatusResponse)
 async def get_ai_status():
     """Retourne la configuration AI actuelle et les fournisseurs/modèles disponibles."""
-    active_model = (
-        settings.OPENROUTER_MODEL if settings.AI_PROVIDER == "openrouter"
+    active_provider = runtime_ai_config.provider or settings.AI_PROVIDER
+    active_model = runtime_ai_config.model or (
+        settings.OPENROUTER_MODEL if active_provider == "openrouter"
         else settings.GEMINI_MODEL
     )
     return AIStatusResponse(
         ai_enabled=settings.AI_ENABLED,
-        current_provider=settings.AI_PROVIDER,
+        current_provider=active_provider,
         current_model=active_model,
         providers=_build_providers(),
     )
@@ -252,3 +254,67 @@ async def _test_gemini(model: str, prompt: Optional[str], image_b64: Optional[st
         return {"success": True, "response": text[:500], "tokens": tokens}
     except Exception as e:
         return {"success": False, "error": str(e)[:500]}
+
+
+# ─────────────────────────────────────────────────────────────
+# GET /admin/api/ai/config  —  état actuel du runtime config
+# ─────────────────────────────────────────────────────────────
+
+@router.get("/config")
+async def get_runtime_config():
+    """Retourne la configuration AI runtime actuelle (provider + modèle)."""
+    return runtime_ai_config.to_dict()
+
+
+# ─────────────────────────────────────────────────────────────
+# PATCH /admin/api/ai/config  —  changer le provider/modèle live
+# ─────────────────────────────────────────────────────────────
+
+class UpdateAIConfigRequest(BaseModel):
+    provider: Optional[str] = Field(None, description="openrouter ou gemini")
+    model: Optional[str] = Field(None, description="Nom du modèle à activer")
+    reset: bool = Field(False, description="true = réinitialiser aux valeurs .env")
+
+class UpdateAIConfigResponse(BaseModel):
+    provider: str
+    model: str
+    is_overridden: bool
+    message: str
+
+
+@router.patch("/config", response_model=UpdateAIConfigResponse)
+async def update_runtime_config(
+    body: UpdateAIConfigRequest,
+    _=Depends(require_scope("admin")),
+):
+    """Change le fournisseur et/ou le modèle AI actif sans redémarrer."""
+    if body.reset:
+        runtime_ai_config.clear()
+        state = runtime_ai_config.to_dict()
+        return UpdateAIConfigResponse(
+            provider=state["provider"],
+            model=state["model"],
+            is_overridden=False,
+            message="Configuration AI réinitialisée aux valeurs .env",
+        )
+
+    if not body.provider and not body.model:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Spécifiez provider et/ou model, ou reset=true",
+        )
+
+    runtime_ai_config.set(provider=body.provider, model=body.model)
+    state = runtime_ai_config.to_dict()
+
+    logger.info("ai.runtime_config.updated", extra={
+        "provider": state["provider"],
+        "model": state["model"],
+    })
+
+    return UpdateAIConfigResponse(
+        provider=state["provider"],
+        model=state["model"],
+        is_overridden=True,
+        message=f"Fournisseur changé à {state['provider']}, modèle {state['model']}",
+    )

app/services/ai_vision.py

@@ -22,6 +22,7 @@ from google.genai import types
 
 from app.config import settings
 from app.services.storage_backend import get_storage_backend
+from app.services.runtime_config import runtime_ai_config
 
 logger = logging.getLogger(__name__)
 
@@ -128,7 +129,7 @@ async def _generate_gemini(
         contents.append(types.Part.from_bytes(data=image_bytes, mime_type=media_type))
     contents.append(prompt)
 
-    model = model_override or settings.GEMINI_MODEL
+    model = model_override or runtime_ai_config.model or settings.GEMINI_MODEL
 
     async def _call():
         return await asyncio.wait_for(
@@ -165,7 +166,7 @@ async def _generate_openrouter(
         logger.warning("ai.openrouter.no_key")
         return {"text": None, "usage": (None, None)}
 
-    model = model_override or settings.OPENROUTER_MODEL
+    model = model_override or runtime_ai_config.model or settings.OPENROUTER_MODEL
 
     headers = {
         "Authorization": f"Bearer {settings.OPENROUTER_API_KEY}",
@@ -233,7 +234,7 @@ async def _generate(
     model_override: Optional[str] = None,
 ) -> dict:
     """Dispatcher vers le bon provider, avec override optionnel par client."""
-    provider = provider_override or settings.AI_PROVIDER.lower()
+    provider = provider_override or runtime_ai_config.provider or settings.AI_PROVIDER.lower()
     logger.info("ai.generate", extra={"provider": provider})
 
     if provider == "openrouter":
@@ -289,8 +290,8 @@ async def analyze_image(
     if not settings.AI_ENABLED:
         return {}
 
-    active_provider = provider_override or settings.AI_PROVIDER
-    active_model = model_override or (
+    active_provider = provider_override or runtime_ai_config.provider or settings.AI_PROVIDER
+    active_model = model_override or runtime_ai_config.model or (
         settings.OPENROUTER_MODEL if active_provider == "openrouter"
         else settings.GEMINI_MODEL
     )

app/services/runtime_config.py

@@ -0,0 +1,63 @@
+"""
+Runtime AI Config — mutable overrides pour le provider/model actif.
+
+Permet à l'admin de changer le fournisseur/modèle sans redémarrer.
+Les overrides sont stockés en mémoire (perdus au redémarrage du backend).
+"""
+import threading
+from typing import Optional
+
+
+class RuntimeAIConfig:
+    """Singleton thread-safe pour les overrides AI runtime."""
+
+    def __init__(self):
+        self._lock = threading.Lock()
+        self._provider: Optional[str] = None
+        self._model: Optional[str] = None
+
+    @property
+    def provider(self) -> Optional[str]:
+        with self._lock:
+            return self._provider
+
+    @property
+    def model(self) -> Optional[str]:
+        with self._lock:
+            return self._model
+
+    @property
+    def has_override(self) -> bool:
+        with self._lock:
+            return self._provider is not None
+
+    def set(self, provider: Optional[str] = None, model: Optional[str] = None) -> None:
+        """Définit les overrides. None = utiliser le défaut de settings."""
+        with self._lock:
+            self._provider = provider
+            self._model = model
+
+    def clear(self) -> None:
+        """Réinitialise aux valeurs par défaut."""
+        with self._lock:
+            self._provider = None
+            self._model = None
+
+    def to_dict(self) -> dict:
+        """Retourne l'état actuel pour les API."""
+        from app.config import settings
+        with self._lock:
+            return {
+                "provider": self._provider or settings.AI_PROVIDER,
+                "model": self._model or (
+                    settings.OPENROUTER_MODEL if (self._provider or settings.AI_PROVIDER) == "openrouter"
+                    else settings.GEMINI_MODEL
+                ),
+                "is_overridden": self._provider is not None,
+                "override_provider": self._provider,
+                "override_model": self._model,
+            }
+
+
+# Singleton global
+runtime_ai_config = RuntimeAIConfig()

imago-admin/src/api/ai.ts

@@ -1,4 +1,4 @@
-import { apiGet, apiPost } from './client';
+import { apiGet, apiPost, apiPatch } from './client';
 import type { AIStatus, TestModelRequest, TestModelResponse } from '@/types/ai.types';
 
 export async function fetchAIStatus(): Promise<AIStatus> {
@@ -8,3 +8,24 @@ export async function fetchAIStatus(): Promise<AIStatus> {
 export async function testModel(body: TestModelRequest): Promise<TestModelResponse> {
     return apiPost<TestModelResponse>('/admin/api/ai/test', body);
 }
+
+export interface UpdateAIConfigRequest {
+    provider?: string;
+    model?: string;
+    reset?: boolean;
+}
+
+export interface UpdateAIConfigResponse {
+    provider: string;
+    model: string;
+    is_overridden: boolean;
+    message: string;
+}
+
+export async function updateAIConfig(body: UpdateAIConfigRequest): Promise<UpdateAIConfigResponse> {
+    return apiPatch<UpdateAIConfigResponse>('/admin/api/ai/config', body);
+}
+
+export async function fetchRuntimeConfig(): Promise<UpdateAIConfigResponse> {
+    return apiGet<UpdateAIConfigResponse>('/admin/api/ai/config');
+}

imago-admin/src/components/admin/AIConfigSection.tsx

@@ -1,6 +1,6 @@
 import { useState, useEffect, useCallback } from 'react';
 import { useQuery } from '@tanstack/react-query';
-import { fetchAIStatus, testModel } from '@/api/ai';
+import { fetchAIStatus, testModel, updateAIConfig } from '@/api/ai';
 import type { TestModelResponse } from '@/types/ai.types';
 import { Bot, Zap, AlertTriangle, CheckCircle, Loader2, RefreshCw, Cpu, ChevronDown } from 'lucide-react';
 import { clsx } from 'clsx';
@@ -18,6 +18,8 @@ export function AIConfigSection() {
     const [testResult, setTestResult] = useState<TestModelResponse | null>(null);
     const [isTesting, setIsTesting] = useState(false);
     const [testError, setTestError] = useState<string | null>(null);
+    const [isSaving, setIsSaving] = useState(false);
+    const [saveMessage, setSaveMessage] = useState<string | null>(null);
 
     // Sync dropdowns with current config when data loads
     useEffect(() => {
@@ -64,6 +66,26 @@ export function AIConfigSection() {
         }
     }, [selectedProvider, selectedModel]);
 
+    const handleSetActive = useCallback(async () => {
+        if (!selectedProvider || !selectedModel) return;
+
+        setIsSaving(true);
+        setSaveMessage(null);
+        try {
+            const result = await updateAIConfig({
+                provider: selectedProvider,
+                model: selectedModel,
+            });
+            setSaveMessage(result.message);
+            // Auto-clear message after 4s
+            setTimeout(() => setSaveMessage(null), 4000);
+        } catch (err: any) {
+            setSaveMessage(err?.message || 'Erreur lors de la mise à jour');
+        } finally {
+            setIsSaving(false);
+        }
+    }, [selectedProvider, selectedModel]);
+
     if (isLoading) {
         return (
             <section className="card mb-6">
@@ -240,6 +262,30 @@ export function AIConfigSection() {
                     )}
                 </button>
 
+                <button
+                    onClick={handleSetActive}
+                    disabled={isSaving || !selectedProvider || !selectedModel}
+                    className="btn-secondary flex items-center gap-2 text-sm disabled:opacity-50 ml-3"
+                >
+                    {isSaving ? (
+                        <>
+                            <Loader2 size={14} className="animate-spin" />
+                            Application...
+                        </>
+                    ) : (
+                        <>
+                            <CheckCircle size={14} />
+                            Définir comme actif
+                        </>
+                    )}
+                </button>
+
+                {saveMessage && (
+                    <span className="ml-3 text-sm text-status-ok animate-fade-in">
+                        {saveMessage}
+                    </span>
+                )}
+
                 {/* Test result — live, no refresh needed */}
                 {(testResult || testError || isTesting) && (
                     <div className={clsx(