feat(llm): basic cost multiplier

apps/client/src/widgets/type_widgets/llm_chat/LlmChat.tsx

@@ -41,6 +41,11 @@ interface LlmChatContent {
     enableExtendedThinking?: boolean;
 }
 
+/** Extended model info with cost description for dropdown display */
+interface ModelOption extends LlmModelInfo {
+    costDescription?: string;
+}
+
 export default function LlmChat({ note, ntxId, noteContext }: TypeWidgetProps) {
     const [messages, setMessages] = useState<StoredMessage[]>([]);
     const [input, setInput] = useState("");
@@ -49,7 +54,7 @@ export default function LlmChat({ note, ntxId, noteContext }: TypeWidgetProps) {
     const [streamingThinking, setStreamingThinking] = useState("");
     const [toolActivity, setToolActivity] = useState<string | null>(null);
     const [pendingCitations, setPendingCitations] = useState<LlmCitation[]>([]);
-    const [availableModels, setAvailableModels] = useState<LlmModelInfo[]>([]);
+    const [availableModels, setAvailableModels] = useState<ModelOption[]>([]);
     const [selectedModel, setSelectedModel] = useState<string>("");
     const [enableWebSearch, setEnableWebSearch] = useState(true);
     const [enableNoteTools, setEnableNoteTools] = useState(false);
@@ -62,7 +67,14 @@ export default function LlmChat({ note, ntxId, noteContext }: TypeWidgetProps) {
     // Fetch available models on mount
     useEffect(() => {
         getAvailableModels().then(models => {
-            setAvailableModels(models);
+            // Add cost description for display
+            const modelsWithDescription = models.map(m => ({
+                ...m,
+                costDescription: m.costMultiplier
+                    ? `${m.costMultiplier}x cost`
+                    : undefined
+            }));
+            setAvailableModels(modelsWithDescription);
             // Set default model if not already selected
             if (!selectedModel) {
                 const defaultModel = models.find(m => m.isDefault) || models[0];
@@ -384,6 +396,7 @@ export default function LlmChat({ note, ntxId, noteContext }: TypeWidgetProps) {
                             values={availableModels}
                             keyProperty="id"
                             titleProperty="name"
+                            descriptionProperty="costDescription"
                             currentValue={selectedModel}
                             onChange={handleModelChange}
                             disabled={isStreaming}

apps/server/src/services/llm/providers/anthropic.ts

@@ -8,10 +8,18 @@ import type { LlmProvider, LlmProviderConfig, ModelInfo, ModelPricing, StreamRes
 const DEFAULT_MODEL = "claude-sonnet-4-20250514";
 const DEFAULT_MAX_TOKENS = 8096;
 
+/**
+ * Calculate effective cost for comparison (weighted average: 1 input + 3 output).
+ * Output is weighted more heavily as it's typically the dominant cost factor.
+ */
+function effectiveCost(pricing: ModelPricing): number {
+    return (pricing.input + 3 * pricing.output) / 4;
+}
+
 /**
  * Available Anthropic models with pricing (USD per million tokens).
  */
-const AVAILABLE_MODELS: ModelInfo[] = [
+const BASE_MODELS: Omit<ModelInfo, "costMultiplier">[] = [
     // Claude 4 family
     {
         id: "claude-sonnet-4-20250514",
@@ -37,6 +45,15 @@ const AVAILABLE_MODELS: ModelInfo[] = [
     }
 ];
 
+// Find cheapest model as baseline for cost multiplier
+const baselineCost = Math.min(...BASE_MODELS.map(m => effectiveCost(m.pricing)));
+
+// Build models with cost multipliers
+const AVAILABLE_MODELS: ModelInfo[] = BASE_MODELS.map(m => ({
+    ...m,
+    costMultiplier: Math.round((effectiveCost(m.pricing) / baselineCost) * 10) / 10
+}));
+
 // Build pricing lookup from available models
 const MODEL_PRICING: Record<string, ModelPricing> = Object.fromEntries(
     AVAILABLE_MODELS.map(m => [m.id, m.pricing])

apps/server/src/services/llm/types.ts

@@ -42,6 +42,8 @@ export interface ModelInfo {
     pricing: ModelPricing;
     /** Whether this is the default model */
     isDefault?: boolean;
+    /** Cost multiplier relative to the cheapest model (1x = cheapest) */
+    costMultiplier?: number;
 }
 
 export interface LlmProvider {

packages/commons/src/lib/llm_api.ts

@@ -63,6 +63,8 @@ export interface LlmModelInfo {
     pricing: LlmModelPricing;
     /** Whether this is the default model */
     isDefault?: boolean;
+    /** Cost multiplier relative to the cheapest model (1x = cheapest) */
+    costMultiplier?: number;
 }
 
 /**