feat: Switching models logic for ChatForm or when regenerating messges + modality detection logic

tools/server/webui/src/lib/components/app/chat/ChatForm/ChatForm.svelte

@@ -9,8 +9,14 @@
 	} from '$lib/components/app';
 	import { INPUT_CLASSES } from '$lib/constants/input-classes';
 	import { config } from '$lib/stores/settings.svelte';
-	import { selectedModelId } from '$lib/stores/models.svelte';
-	import { isRouterMode } from '$lib/stores/props.svelte';
+	import { modelOptions, selectedModelId } from '$lib/stores/models.svelte';
+	import {
+		isRouterMode,
+		supportsAudio,
+		supportsVision,
+		fetchModelProps,
+		getModelProps
+	} from '$lib/stores/props.svelte';
 	import { getConversationModel } from '$lib/stores/chat.svelte';
 	import { activeMessages } from '$lib/stores/conversations.svelte';
 	import {
@@ -74,6 +80,68 @@
 	let isRouter = $derived(isRouterMode());
 	let hasModelSelected = $derived(!isRouter || !!conversationModel || !!selectedModelId());
 
+	// Get active model ID for capability detection
+	let activeModelId = $derived.by(() => {
+		if (!isRouter) return null;
+
+		const options = modelOptions();
+
+		// First try user-selected model
+		const selectedId = selectedModelId();
+		if (selectedId) {
+			const model = options.find((m) => m.id === selectedId);
+			if (model) return model.model;
+		}
+
+		// Fallback to conversation model
+		if (conversationModel) {
+			const model = options.find((m) => m.model === conversationModel);
+			if (model) return model.model;
+		}
+
+		return null;
+	});
+
+	// State for model props reactivity
+	let modelPropsVersion = $state(0);
+
+	// Fetch model props when active model changes
+	$effect(() => {
+		if (isRouter && activeModelId) {
+			const cached = getModelProps(activeModelId);
+			if (!cached) {
+				fetchModelProps(activeModelId).then(() => {
+					modelPropsVersion++;
+				});
+			}
+		}
+	});
+
+	// Derive modalities from model props (ROUTER) or server props (MODEL)
+	let hasAudioModality = $derived.by(() => {
+		if (!isRouter) return supportsAudio();
+
+		if (activeModelId) {
+			void modelPropsVersion;
+			const props = getModelProps(activeModelId);
+			if (props) return props.modalities?.audio ?? false;
+		}
+
+		return false;
+	});
+
+	let hasVisionModality = $derived.by(() => {
+		if (!isRouter) return supportsVision();
+
+		if (activeModelId) {
+			void modelPropsVersion;
+			const props = getModelProps(activeModelId);
+			if (props) return props.modalities?.vision ?? false;
+		}
+
+		return false;
+	});
+
 	function checkModelSelected(): boolean {
 		if (!hasModelSelected) {
 			// Open the model selector
@@ -251,6 +319,8 @@
 <ChatFormFileInputInvisible
 	bind:this={fileInputRef}
 	bind:accept={fileAcceptString}
+	{hasAudioModality}
+	{hasVisionModality}
 	onFileSelect={handleFileSelect}
 />
 

tools/server/webui/src/lib/components/app/chat/ChatForm/ChatFormActions/ChatFormActionFileAttachments.svelte

@@ -5,18 +5,25 @@
 	import * as Tooltip from '$lib/components/ui/tooltip';
 	import { TOOLTIP_DELAY_DURATION } from '$lib/constants/tooltip-config';
 	import { FileTypeCategory } from '$lib/enums';
-	import { supportsAudio, supportsVision } from '$lib/stores/props.svelte';
 
 	interface Props {
 		class?: string;
 		disabled?: boolean;
+		hasAudioModality?: boolean;
+		hasVisionModality?: boolean;
 		onFileUpload?: (fileType?: FileTypeCategory) => void;
 	}
 
-	let { class: className = '', disabled = false, onFileUpload }: Props = $props();
+	let {
+		class: className = '',
+		disabled = false,
+		hasAudioModality = false,
+		hasVisionModality = false,
+		onFileUpload
+	}: Props = $props();
 
 	const fileUploadTooltipText = $derived.by(() => {
-		return !supportsVision()
+		return !hasVisionModality
 			? 'Text files and PDFs supported. Images, audio, and video require vision models.'
 			: 'Attach files';
 	});
@@ -53,7 +60,7 @@
 				<Tooltip.Trigger class="w-full">
 					<DropdownMenu.Item
 						class="images-button flex cursor-pointer items-center gap-2"
-						disabled={!supportsVision()}
+						disabled={!hasVisionModality}
 						onclick={() => handleFileUpload(FileTypeCategory.IMAGE)}
 					>
 						<Image class="h-4 w-4" />
@@ -62,7 +69,7 @@
 					</DropdownMenu.Item>
 				</Tooltip.Trigger>
 
-				{#if !supportsVision()}
+				{#if !hasVisionModality}
 					<Tooltip.Content>
 						<p>Images require vision models to be processed</p>
 					</Tooltip.Content>
@@ -73,7 +80,7 @@
 				<Tooltip.Trigger class="w-full">
 					<DropdownMenu.Item
 						class="audio-button flex cursor-pointer items-center gap-2"
-						disabled={!supportsAudio()}
+						disabled={!hasAudioModality}
 						onclick={() => handleFileUpload(FileTypeCategory.AUDIO)}
 					>
 						<Volume2 class="h-4 w-4" />
@@ -82,7 +89,7 @@
 					</DropdownMenu.Item>
 				</Tooltip.Trigger>
 
-				{#if !supportsAudio()}
+				{#if !hasAudioModality}
 					<Tooltip.Content>
 						<p>Audio files require audio models to be processed</p>
 					</Tooltip.Content>
@@ -110,7 +117,7 @@
 					</DropdownMenu.Item>
 				</Tooltip.Trigger>
 
-				{#if !supportsVision()}
+				{#if !hasVisionModality}
 					<Tooltip.Content>
 						<p>PDFs will be converted to text. Image-based PDFs may not work properly.</p>
 					</Tooltip.Content>

tools/server/webui/src/lib/components/app/chat/ChatForm/ChatFormActions/ChatFormActionRecord.svelte

@@ -2,11 +2,11 @@
 	import { Mic, Square } from '@lucide/svelte';
 	import { Button } from '$lib/components/ui/button';
 	import * as Tooltip from '$lib/components/ui/tooltip';
-	import { supportsAudio } from '$lib/stores/props.svelte';
 
 	interface Props {
 		class?: string;
 		disabled?: boolean;
+		hasAudioModality?: boolean;
 		isLoading?: boolean;
 		isRecording?: boolean;
 		onMicClick?: () => void;
@@ -15,6 +15,7 @@
 	let {
 		class: className = '',
 		disabled = false,
+		hasAudioModality = false,
 		isLoading = false,
 		isRecording = false,
 		onMicClick
@@ -28,7 +29,7 @@
 				class="h-8 w-8 rounded-full p-0 {isRecording
 					? 'animate-pulse bg-red-500 text-white hover:bg-red-600'
 					: ''}"
-				disabled={disabled || isLoading || !supportsAudio()}
+				disabled={disabled || isLoading || !hasAudioModality}
 				onclick={onMicClick}
 				type="button"
 			>
@@ -42,7 +43,7 @@
 			</Button>
 		</Tooltip.Trigger>
 
-		{#if !supportsAudio()}
+		{#if !hasAudioModality}
 			<Tooltip.Content>
 				<p>Current model does not support audio</p>
 			</Tooltip.Content>

tools/server/webui/src/lib/components/app/chat/ChatForm/ChatFormActions/ChatFormActions.svelte

@@ -9,12 +9,17 @@
 	} from '$lib/components/app';
 	import { FileTypeCategory } from '$lib/enums';
 	import { getFileTypeCategory } from '$lib/utils/file-type';
-	import { supportsAudio } from '$lib/stores/props.svelte';
+	import {
+		supportsAudio,
+		supportsVision,
+		isRouterMode,
+		fetchModelProps,
+		getModelProps
+	} from '$lib/stores/props.svelte';
 	import { config } from '$lib/stores/settings.svelte';
 	import { modelOptions, selectedModelId, selectModelByName } from '$lib/stores/models.svelte';
 	import { getConversationModel } from '$lib/stores/chat.svelte';
 	import { activeMessages } from '$lib/stores/conversations.svelte';
-	import { isRouterMode } from '$lib/stores/props.svelte';
 	import type { ChatUploadedFile } from '$lib/types/chat';
 
 	interface Props {
@@ -44,7 +49,84 @@
 	}: Props = $props();
 
 	let currentConfig = $derived(config());
-	let hasAudioModality = $derived(supportsAudio());
+	let isRouter = $derived(isRouterMode());
+
+	let conversationModel = $derived(getConversationModel(activeMessages() as DatabaseMessage[]));
+
+	let previousConversationModel: string | null = null;
+
+	$effect(() => {
+		if (conversationModel && conversationModel !== previousConversationModel) {
+			previousConversationModel = conversationModel;
+			selectModelByName(conversationModel);
+		}
+	});
+
+	// Get active model ID for fetching props
+	// Priority: user-selected model > conversation model (allows changing model mid-chat)
+	let activeModelId = $derived.by(() => {
+		if (!isRouter) return null;
+
+		const options = modelOptions();
+
+		const selectedId = selectedModelId();
+		if (selectedId) {
+			const model = options.find((m) => m.id === selectedId);
+			if (model) return model.model;
+		}
+
+		if (conversationModel) {
+			const model = options.find((m) => m.model === conversationModel);
+			if (model) return model.model;
+		}
+
+		return null;
+	});
+
+	// State for model props (fetched from /props?model=<id>)
+	let modelPropsVersion = $state(0); // Used to trigger reactivity after fetch
+
+	// Fetch model props when active model changes
+	$effect(() => {
+		if (isRouter && activeModelId) {
+			// Check if we already have cached props
+			const cached = getModelProps(activeModelId);
+			if (!cached) {
+				// Fetch props for this model
+				fetchModelProps(activeModelId).then(() => {
+					// Trigger reactivity update
+					modelPropsVersion++;
+				});
+			}
+		}
+	});
+
+	let hasAudioModality = $derived.by(() => {
+		if (!isRouter) return supportsAudio();
+
+		if (activeModelId) {
+			void modelPropsVersion;
+
+			const props = getModelProps(activeModelId);
+			if (props) return props.modalities?.audio ?? false;
+		}
+
+		return false;
+	});
+
+	let hasVisionModality = $derived.by(() => {
+		if (!isRouter) return supportsVision();
+
+		if (activeModelId) {
+			void modelPropsVersion;
+
+			const props = getModelProps(activeModelId);
+			if (props) return props.modalities?.vision ?? false;
+		}
+
+		return false;
+	});
+
 	let hasAudioAttachments = $derived(
 		uploadedFiles.some((file) => getFileTypeCategory(file.type) === FileTypeCategory.AUDIO)
 	);
@@ -52,22 +134,6 @@
 		hasAudioModality && !hasText && !hasAudioAttachments && currentConfig.autoMicOnEmpty
 	);
 
-	// Get model from conversation messages (last assistant message with model)
-	let conversationModel = $derived(getConversationModel(activeMessages() as DatabaseMessage[]));
-
-	// Sync selected model with conversation model when it changes
-	// Only sync when conversation HAS a model - don't clear selection for new chats
-	// to allow user to select a model before first message
-	$effect(() => {
-		if (conversationModel) {
-			selectModelByName(conversationModel);
-		}
-	});
-
-	let isRouter = $derived(isRouterMode());
-
-	// Check if any model is selected (either from conversation or user selection)
-	// In single MODEL mode, there's always a model available
 	let hasModelSelected = $derived(!isRouter || !!conversationModel || !!selectedModelId());
 
 	let isSelectedModelInCache = $derived.by(() => {
@@ -91,28 +157,35 @@
 		if (!hasModelSelected) {
 			return 'Please select a model first';
 		}
+
 		if (!isSelectedModelInCache) {
 			return 'Selected model is not available, please select another';
 		}
+
 		return '';
 	});
 
-	// Ref to SelectorModel for programmatic opening
 	let selectorModelRef: SelectorModel | undefined = $state(undefined);
 
-	// Export function to open the model selector
 	export function openModelSelector() {
 		selectorModelRef?.open();
 	}
 </script>
 
 <div class="flex w-full items-center gap-3 {className}" style="container-type: inline-size">
-	<ChatFormActionFileAttachments class="mr-auto" {disabled} {onFileUpload} />
+	<ChatFormActionFileAttachments
+		class="mr-auto"
+		{disabled}
+		{hasAudioModality}
+		{hasVisionModality}
+		{onFileUpload}
+	/>
 
 	<SelectorModel
 		bind:this={selectorModelRef}
 		currentModel={conversationModel}
 		forceForegroundText={true}
+		useGlobalSelection={true}
 	/>
 
 	{#if isLoading}
@@ -125,7 +198,7 @@
 			<Square class="h-8 w-8 fill-destructive stroke-destructive" />
 		</Button>
 	{:else if shouldShowRecordButton}
-		<ChatFormActionRecord {disabled} {isLoading} {isRecording} {onMicClick} />
+		<ChatFormActionRecord {disabled} {hasAudioModality} {isLoading} {isRecording} {onMicClick} />
 	{:else}
 		<ChatFormActionSubmit
 			canSend={canSend && hasModelSelected && isSelectedModelInCache}

tools/server/webui/src/lib/components/app/chat/ChatForm/ChatFormFileInputInvisible.svelte

@@ -4,6 +4,8 @@
 	interface Props {
 		accept?: string;
 		class?: string;
+		hasAudioModality?: boolean;
+		hasVisionModality?: boolean;
 		multiple?: boolean;
 		onFileSelect?: (files: File[]) => void;
 	}
@@ -11,6 +13,8 @@
 	let {
 		accept = $bindable(),
 		class: className = '',
+		hasAudioModality = false,
+		hasVisionModality = false,
 		multiple = true,
 		onFileSelect
 	}: Props = $props();
@@ -18,7 +22,13 @@
 	let fileInputElement: HTMLInputElement | undefined;
 
 	// Use modality-aware accept string by default, but allow override
-	let finalAccept = $derived(accept ?? generateModalityAwareAcceptString());
+	let finalAccept = $derived(
+		accept ??
+			generateModalityAwareAcceptString({
+				hasVision: hasVisionModality,
+				hasAudio: hasAudioModality
+			})
+	);
 
 	export function click() {
 		fileInputElement?.click();

tools/server/webui/src/lib/components/app/chat/ChatMessages/ChatMessage.svelte

@@ -20,7 +20,7 @@
 		) => void;
 		onEditUserMessagePreserveResponses?: (message: DatabaseMessage, newContent: string) => void;
 		onNavigateToSibling?: (siblingId: string) => void;
-		onRegenerateWithBranching?: (message: DatabaseMessage) => void;
+		onRegenerateWithBranching?: (message: DatabaseMessage, modelOverride?: string) => void;
 		siblingInfo?: ChatMessageSiblingInfo | null;
 	}
 
@@ -133,8 +133,8 @@
 		}
 	}
 
-	function handleRegenerate() {
-		onRegenerateWithBranching?.(message);
+	function handleRegenerate(modelOverride?: string) {
+		onRegenerateWithBranching?.(message, modelOverride);
 	}
 
 	function handleContinue() {

tools/server/webui/src/lib/components/app/chat/ChatMessages/ChatMessageAssistant.svelte

@@ -44,7 +44,7 @@
 		onEditKeydown?: (event: KeyboardEvent) => void;
 		onEditedContentChange?: (content: string) => void;
 		onNavigateToSibling?: (siblingId: string) => void;
-		onRegenerate: () => void;
+		onRegenerate: (modelOverride?: string) => void;
 		onSaveEdit?: () => void;
 		onShowDeleteDialogChange: (show: boolean) => void;
 		onShouldBranchAfterEditChange?: (value: boolean) => void;
@@ -101,11 +101,12 @@
 		return null;
 	});
 
-	async function handleModelChange(modelId: string) {
+	async function handleModelChange(modelId: string, modelName: string) {
 		try {
 			await selectModel(modelId);
 
-			onRegenerate();
+			// Pass the selected model name for regeneration
+			onRegenerate(modelName);
 		} catch (error) {
 			console.error('Failed to change model:', error);
 		}

tools/server/webui/src/lib/components/app/chat/ChatMessages/ChatMessages.svelte

@@ -87,10 +87,10 @@
 		refreshAllMessages();
 	}
 
-	async function handleRegenerateWithBranching(message: DatabaseMessage) {
+	async function handleRegenerateWithBranching(message: DatabaseMessage, modelOverride?: string) {
 		onUserAction?.();
 
-		await regenerateMessageWithBranching(message.id);
+		await regenerateMessageWithBranching(message.id, modelOverride);
 
 		refreshAllMessages();
 	}

tools/server/webui/src/lib/components/app/chat/ChatScreen/ChatScreen.svelte

@@ -36,8 +36,13 @@
 		supportsAudio,
 		propsLoading,
 		serverWarning,
-		propsStore
+		propsStore,
+		isRouterMode,
+		fetchModelProps,
+		getModelProps
 	} from '$lib/stores/props.svelte';
+	import { modelOptions, selectedModelId } from '$lib/stores/models.svelte';
+	import { getConversationModel } from '$lib/stores/chat.svelte';
 	import { parseFilesToMessageExtras } from '$lib/utils/convert-files-to-extra';
 	import { isFileTypeSupported } from '$lib/utils/file-type';
 	import { filterFilesByModalities } from '$lib/utils/modality-file-validation';
@@ -89,6 +94,72 @@
 
 	let isCurrentConversationLoading = $derived(isLoading());
 
+	// Model-specific capability detection (same logic as ChatFormActions)
+	let isRouter = $derived(isRouterMode());
+	let conversationModel = $derived(getConversationModel(activeMessages() as DatabaseMessage[]));
+
+	// Get active model ID for fetching props
+	let activeModelId = $derived.by(() => {
+		if (!isRouter) return null;
+
+		const options = modelOptions();
+
+		// First try user-selected model
+		const selectedId = selectedModelId();
+		if (selectedId) {
+			const model = options.find((m) => m.id === selectedId);
+			if (model) return model.model;
+		}
+
+		// Fallback to conversation model
+		if (conversationModel) {
+			const model = options.find((m) => m.model === conversationModel);
+			if (model) return model.model;
+		}
+
+		return null;
+	});
+
+	// State for model props reactivity
+	let modelPropsVersion = $state(0);
+
+	// Fetch model props when active model changes
+	$effect(() => {
+		if (isRouter && activeModelId) {
+			const cached = getModelProps(activeModelId);
+			if (!cached) {
+				fetchModelProps(activeModelId).then(() => {
+					modelPropsVersion++;
+				});
+			}
+		}
+	});
+
+	// Derive modalities from model props (ROUTER) or server props (MODEL)
+	let hasAudioModality = $derived.by(() => {
+		if (!isRouter) return supportsAudio();
+
+		if (activeModelId) {
+			void modelPropsVersion;
+			const props = getModelProps(activeModelId);
+			if (props) return props.modalities?.audio ?? false;
+		}
+
+		return false;
+	});
+
+	let hasVisionModality = $derived.by(() => {
+		if (!isRouter) return supportsVision();
+
+		if (activeModelId) {
+			void modelPropsVersion;
+			const props = getModelProps(activeModelId);
+			if (props) return props.modalities?.vision ?? false;
+		}
+
+		return false;
+	});
+
 	async function handleDeleteConfirm() {
 		const conversation = activeConversation();
 		if (conversation) {
@@ -220,16 +291,20 @@
 			}
 		}
 
-		const { supportedFiles, unsupportedFiles, modalityReasons } =
-			filterFilesByModalities(generallySupported);
+		// Use model-specific capabilities for file validation
+		const capabilities = { hasVision: hasVisionModality, hasAudio: hasAudioModality };
+		const { supportedFiles, unsupportedFiles, modalityReasons } = filterFilesByModalities(
+			generallySupported,
+			capabilities
+		);
 
 		const allUnsupportedFiles = [...generallyUnsupported, ...unsupportedFiles];
 
 		if (allUnsupportedFiles.length > 0) {
 			const supportedTypes: string[] = ['text files', 'PDFs'];
 
-			if (supportsVision()) supportedTypes.push('images');
-			if (supportsAudio()) supportedTypes.push('audio files');
+			if (hasVisionModality) supportedTypes.push('images');
+			if (hasAudioModality) supportedTypes.push('audio files');
 
 			fileErrorData = {
 				generallyUnsupported,

tools/server/webui/src/lib/components/app/misc/SelectorModel.svelte

@@ -21,6 +21,8 @@
 		onModelChange?: (modelId: string, modelName: string) => void;
 		disabled?: boolean;
 		forceForegroundText?: boolean;
+		/** When true, user's global selection takes priority over currentModel (for form selector) */
+		useGlobalSelection?: boolean;
 	}
 
 	let {
@@ -28,7 +30,8 @@
 		currentModel = null,
 		onModelChange,
 		disabled = false,
-		forceForegroundText = false
+		forceForegroundText = false,
+		useGlobalSelection = false
 	}: Props = $props();
 
 	let options = $derived(modelOptions());
@@ -260,6 +263,14 @@
 			return undefined;
 		}
 
+		// When useGlobalSelection is true (form selector), prioritize user selection
+		// Otherwise (message display), prioritize currentModel
+		if (useGlobalSelection && activeId) {
+			const selected = options.find((option) => option.id === activeId);
+			if (selected) return selected;
+		}
+
+		// Show currentModel (from message payload or conversation)
 		if (currentModel) {
 			if (!isCurrentModelInCache()) {
 				return {
@@ -273,7 +284,7 @@
 			return options.find((option) => option.model === currentModel);
 		}
 
-		// Check if user has selected a model (for new chats before first message)
+		// Fallback to user selection (for new chats before first message)
 		if (activeId) {
 			return options.find((option) => option.id === activeId);
 		}

tools/server/webui/src/lib/services/chat.ts

@@ -150,7 +150,7 @@ export class ChatService {
 		};
 
 		const isRouter = isRouterMode();
-		const activeModel = isRouter ? selectedModelName() : null;
+		const activeModel = isRouter ? options.model || selectedModelName() : null;
 
 		if (isRouter && activeModel) {
 			requestBody.model = activeModel;

tools/server/webui/src/lib/services/props.ts

@@ -40,4 +40,34 @@ export class PropsService {
 		const data = await response.json();
 		return data as ApiLlamaCppServerProps;
 	}
+
+	/**
+	 * Fetches server properties for a specific model (ROUTER mode)
+	 *
+	 * @param modelId - The model ID to fetch properties for
+	 * @returns {Promise<ApiLlamaCppServerProps>} Server properties for the model
+	 * @throws {Error} If the request fails or returns invalid data
+	 */
+	static async fetchForModel(modelId: string): Promise<ApiLlamaCppServerProps> {
+		const currentConfig = config();
+		const apiKey = currentConfig.apiKey?.toString().trim();
+
+		const url = new URL('./props', window.location.href);
+		url.searchParams.set('model', modelId);
+
+		const response = await fetch(url.toString(), {
+			headers: {
+				...(apiKey ? { Authorization: `Bearer ${apiKey}` } : {})
+			}
+		});
+
+		if (!response.ok) {
+			throw new Error(
+				`Failed to fetch model properties: ${response.status} ${response.statusText}`
+			);
+		}
+
+		const data = await response.json();
+		return data as ApiLlamaCppServerProps;
+	}
 }

tools/server/webui/src/lib/stores/chat.svelte.ts

@@ -489,7 +489,8 @@ class ChatStore {
 		allMessages: DatabaseMessage[],
 		assistantMessage: DatabaseMessage,
 		onComplete?: (content: string) => Promise<void>,
-		onError?: (error: Error) => void
+		onError?: (error: Error) => void,
+		modelOverride?: string | null
 	): Promise<void> {
 		let streamedContent = '';
 		let streamedReasoningContent = '';
@@ -520,6 +521,7 @@ class ChatStore {
 			allMessages,
 			{
 				...this.getApiOptions(),
+				...(modelOverride ? { model: modelOverride } : {}),
 				onChunk: (chunk: string) => {
 					streamedContent += chunk;
 					this.setChatStreaming(assistantMessage.convId, streamedContent, assistantMessage.id);
@@ -996,7 +998,7 @@ class ChatStore {
 		}
 	}
 
-	async regenerateMessageWithBranching(messageId: string): Promise<void> {
+	async regenerateMessageWithBranching(messageId: string, modelOverride?: string): Promise<void> {
 		const activeConv = conversationsStore.activeConversation;
 		if (!activeConv || this.isLoading) return;
 		try {
@@ -1035,7 +1037,16 @@ class ChatStore {
 				parentMessage.id,
 				false
 			) as DatabaseMessage[];
-			await this.streamChatCompletion(conversationPath, newAssistantMessage);
+			// Use modelOverride if provided, otherwise use the original message's model
+			// If neither is available, don't pass model (will use global selection)
+			const modelToUse = modelOverride || msg.model || undefined;
+			await this.streamChatCompletion(
+				conversationPath,
+				newAssistantMessage,
+				undefined,
+				undefined,
+				modelToUse
+			);
 		} catch (error) {
 			if (!this.isAbortError(error))
 				console.error('Failed to regenerate message with branching:', error);

tools/server/webui/src/lib/stores/props.svelte.ts

@@ -39,6 +39,10 @@ class PropsStore {
 	private _serverMode = $state<ServerMode | null>(null);
 	private fetchPromise: Promise<void> | null = null;
 
+	// Model-specific props cache (ROUTER mode)
+	private _modelPropsCache = $state<Map<string, ApiLlamaCppServerProps>>(new Map());
+	private _modelPropsFetching = $state<Set<string>>(new Set());
+
 	// ─────────────────────────────────────────────────────────────────────────────
 	// LocalStorage persistence
 	// ─────────────────────────────────────────────────────────────────────────────
@@ -238,6 +242,52 @@ class PropsStore {
 		await fetchPromise;
 	}
 
+	// ─────────────────────────────────────────────────────────────────────────────
+	// Fetch Model-Specific Properties (ROUTER mode)
+	// ─────────────────────────────────────────────────────────────────────────────
+
+	/**
+	 * Get cached props for a specific model
+	 */
+	getModelProps(modelId: string): ApiLlamaCppServerProps | null {
+		return this._modelPropsCache.get(modelId) ?? null;
+	}
+
+	/**
+	 * Check if model props are being fetched
+	 */
+	isModelPropsFetching(modelId: string): boolean {
+		return this._modelPropsFetching.has(modelId);
+	}
+
+	/**
+	 * Fetches properties for a specific model (ROUTER mode)
+	 * Results are cached for subsequent calls
+	 */
+	async fetchModelProps(modelId: string): Promise<ApiLlamaCppServerProps | null> {
+		// Return cached if available
+		const cached = this._modelPropsCache.get(modelId);
+		if (cached) return cached;
+
+		// Don't fetch if already fetching
+		if (this._modelPropsFetching.has(modelId)) {
+			return null;
+		}
+
+		this._modelPropsFetching.add(modelId);
+
+		try {
+			const props = await PropsService.fetchForModel(modelId);
+			this._modelPropsCache.set(modelId, props);
+			return props;
+		} catch (error) {
+			console.warn(`Failed to fetch props for model ${modelId}:`, error);
+			return null;
+		} finally {
+			this._modelPropsFetching.delete(modelId);
+		}
+	}
+
 	// ─────────────────────────────────────────────────────────────────────────────
 	// Error Handling
 	// ─────────────────────────────────────────────────────────────────────────────
@@ -365,3 +415,5 @@ export const isModelMode = () => propsStore.isModelMode;
 
 // Actions
 export const fetchProps = propsStore.fetch.bind(propsStore);
+export const fetchModelProps = propsStore.fetchModelProps.bind(propsStore);
+export const getModelProps = propsStore.getModelProps.bind(propsStore);

tools/server/webui/src/lib/types/settings.d.ts

@@ -14,6 +14,8 @@ export interface SettingsFieldConfig {
 
 export interface SettingsChatServiceOptions {
 	stream?: boolean;
+	// Model override (for regenerate with specific model)
+	model?: string;
 	// Generation parameters
 	temperature?: number;
 	max_tokens?: number;

tools/server/webui/src/lib/utils/modality-file-validation.ts

@@ -4,7 +4,6 @@
  */
 
 import { getFileTypeCategory } from '$lib/utils/file-type';
-import { supportsVision, supportsAudio } from '$lib/stores/props.svelte';
 import {
 	FileExtensionAudio,
 	FileExtensionImage,
@@ -17,13 +16,24 @@ import {
 	FileTypeCategory
 } from '$lib/enums';
 
+/** Modality capabilities for file validation */
+export interface ModalityCapabilities {
+	hasVision: boolean;
+	hasAudio: boolean;
+}
+
 /**
- * Check if a file type is supported by the current model's modalities
+ * Check if a file type is supported by the given modalities
  * @param filename - The filename to check
  * @param mimeType - The MIME type of the file
- * @returns true if the file type is supported by the current model
+ * @param capabilities - The modality capabilities to check against
+ * @returns true if the file type is supported
  */
-export function isFileTypeSupportedByModel(filename: string, mimeType?: string): boolean {
+export function isFileTypeSupportedByModel(
+	filename: string,
+	mimeType: string | undefined,
+	capabilities: ModalityCapabilities
+): boolean {
 	const category = mimeType ? getFileTypeCategory(mimeType) : null;
 
 	// If we can't determine the category from MIME type, fall back to general support check
@@ -44,11 +54,11 @@ export function isFileTypeSupportedByModel(filename: string, mimeType?: string):
 
 		case FileTypeCategory.IMAGE:
 			// Images require vision support
-			return supportsVision();
+			return capabilities.hasVision;
 
 		case FileTypeCategory.AUDIO:
 			// Audio files require audio support
-			return supportsAudio();
+			return capabilities.hasAudio;
 
 		default:
 			// Unknown categories - be conservative and allow
@@ -59,9 +69,13 @@ export function isFileTypeSupportedByModel(filename: string, mimeType?: string):
 /**
  * Filter files based on model modalities and return supported/unsupported lists
  * @param files - Array of files to filter
+ * @param capabilities - The modality capabilities to check against
  * @returns Object with supportedFiles and unsupportedFiles arrays
  */
-export function filterFilesByModalities(files: File[]): {
+export function filterFilesByModalities(
+	files: File[],
+	capabilities: ModalityCapabilities
+): {
 	supportedFiles: File[];
 	unsupportedFiles: File[];
 	modalityReasons: Record<string, string>;
@@ -70,8 +84,7 @@ export function filterFilesByModalities(files: File[]): {
 	const unsupportedFiles: File[] = [];
 	const modalityReasons: Record<string, string> = {};
 
-	const hasVision = supportsVision();
-	const hasAudio = supportsAudio();
+	const { hasVision, hasAudio } = capabilities;
 
 	for (const file of files) {
 		const category = getFileTypeCategory(file.type);
@@ -119,16 +132,17 @@ export function filterFilesByModalities(files: File[]): {
  * Generate a user-friendly error message for unsupported files
  * @param unsupportedFiles - Array of unsupported files
  * @param modalityReasons - Reasons why files are unsupported
+ * @param capabilities - The modality capabilities to check against
  * @returns Formatted error message
  */
 export function generateModalityErrorMessage(
 	unsupportedFiles: File[],
-	modalityReasons: Record<string, string>
+	modalityReasons: Record<string, string>,
+	capabilities: ModalityCapabilities
 ): string {
 	if (unsupportedFiles.length === 0) return '';
 
-	const hasVision = supportsVision();
-	const hasAudio = supportsAudio();
+	const { hasVision, hasAudio } = capabilities;
 
 	let message = '';
 
@@ -152,12 +166,12 @@ export function generateModalityErrorMessage(
 }
 
 /**
- * Generate file input accept string based on current model modalities
+ * Generate file input accept string based on model modalities
+ * @param capabilities - The modality capabilities to check against
  * @returns Accept string for HTML file input element
  */
-export function generateModalityAwareAcceptString(): string {
-	const hasVision = supportsVision();
-	const hasAudio = supportsAudio();
+export function generateModalityAwareAcceptString(capabilities: ModalityCapabilities): string {
+	const { hasVision, hasAudio } = capabilities;
 
 	const acceptedExtensions: string[] = [];
 	const acceptedMimeTypes: string[] = [];