Add support for configuring router multimodal model via env

Introduces the LLM_ROUTER_MULTIMODAL_MODEL environment variable to allow specifying a preferred multimodal model for the router. If set, the router will use the configured model for multimodal requests; otherwise, it falls back to the first available multimodal model. Updates are reflected in .env, prod.yaml, and endpoint.ts.

.env

@@ -65,6 +65,8 @@ LLM_ROUTER_ARCH_TIMEOUT_MS=10000
 
 # Enable router multimodal fallback (set to true to allow image inputs via router)
 LLM_ROUTER_ENABLE_MULTIMODAL=false
+# Optional: specific model to use for multimodal requests. If not set, uses first multimodal model
+LLM_ROUTER_MULTIMODAL_MODEL=
 
 # Router UI overrides (client-visible)
 # Public display name for the router entry in the model list. Defaults to "Omni".

chart/env/prod.yaml

@@ -73,6 +73,7 @@ envVars:
   LLM_ROUTER_OTHER_ROUTE: "casual_conversation"
   LLM_ROUTER_ARCH_TIMEOUT_MS: "10000"
   LLM_ROUTER_ENABLE_MULTIMODAL: "true"
+  LLM_ROUTER_MULTIMODAL_MODEL: "Qwen/Qwen3-VL-235B-A22B-Thinking"
   PUBLIC_LLM_ROUTER_DISPLAY_NAME: "Omni"
   PUBLIC_LLM_ROUTER_LOGO_URL: "https://cdn-uploads.huggingface.co/production/uploads/5f17f0a0925b9863e28ad517/C5V0v1xZXv6M7FXsdJH9b.png"
   PUBLIC_LLM_ROUTER_ALIAS_ID: "omni"

src/lib/server/router/endpoint.ts

@@ -161,6 +161,27 @@ export async function makeRouterEndpoint(routerModel: ProcessedModel): Promise<E
 			try {
 				const mod = await import("../models");
 				const all = (mod as { models: ProcessedModel[] }).models;
+
+				// Check if a specific multimodal model is configured via env variable
+				const preferredModelId = config.LLM_ROUTER_MULTIMODAL_MODEL;
+				if (preferredModelId) {
+					const preferredModel = all?.find(
+						(m) => (m.id === preferredModelId || m.name === preferredModelId) && m.multimodal
+					);
+					if (preferredModel) {
+						logger.info(
+							{ model: preferredModel.id ?? preferredModel.name },
+							"[router] using configured multimodal model"
+						);
+						return preferredModel.id ?? preferredModel.name;
+					}
+					logger.warn(
+						{ configuredModel: preferredModelId },
+						"[router] configured multimodal model not found or not multimodal, falling back to first available"
+					);
+				}
+
+				// Fallback to first multimodal model
 				const first = all?.find((m) => !m.isRouter && m.multimodal);
 				return first?.id ?? first?.name;
 			} catch (e) {