feat(24-02): track incurred cost for video and external providers

- Add SelectedModelPricing interface to providers.ts
- Update SelectedModel type with optional pricing field
- Track fal.ai costs in nanoBanana execution and regeneration
- Track fal.ai costs in generateVideo execution and regeneration
- Skip cost tracking for Replicate (no pricing API available)
- Gemini continues to use hardcoded pricing

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/store/workflowStore.ts

@@ -1021,8 +1021,16 @@ export const useWorkflowStore = create<WorkflowStore>((set, get) => ({
                 });
 
                 // Track cost
-                const generationCost = calculateGenerationCost(nodeData.model, nodeData.resolution);
-                get().addIncurredCost(generationCost);
+                // Cost tracking: Gemini (hardcoded), fal.ai (from API). Replicate excluded (no pricing API).
+                if (nodeData.selectedModel?.provider === "fal" && nodeData.selectedModel?.pricing) {
+                  // External fal.ai provider - use pricing from selectedModel
+                  get().addIncurredCost(nodeData.selectedModel.pricing.amount);
+                } else if (!nodeData.selectedModel || nodeData.selectedModel.provider === "gemini") {
+                  // Legacy Gemini or Gemini via selectedModel - use hardcoded pricing
+                  const generationCost = calculateGenerationCost(nodeData.model, nodeData.resolution);
+                  get().addIncurredCost(generationCost);
+                }
+                // Note: Replicate has no pricing API, so costs are not tracked
 
                 // Auto-save to generations folder if configured
                 const genPath = get().generationsPath;
@@ -1226,6 +1234,13 @@ export const useWorkflowStore = create<WorkflowStore>((set, get) => ({
                   selectedVideoHistoryIndex: 0,
                 });
 
+                // Track cost for video generation
+                // Cost tracking: fal.ai (from API). Replicate excluded (no pricing API).
+                if (nodeData.selectedModel?.provider === "fal" && nodeData.selectedModel?.pricing) {
+                  get().addIncurredCost(nodeData.selectedModel.pricing.amount);
+                }
+                // Note: Replicate has no pricing API, so video costs are not tracked
+
                 // Auto-save video to generations folder if configured
                 const genPath = get().generationsPath;
                 if (genPath) {
@@ -1264,6 +1279,12 @@ export const useWorkflowStore = create<WorkflowStore>((set, get) => ({
                   selectedVideoHistoryIndex: 0,
                 });
 
+                // Track cost for video generation (image fallback case)
+                // Cost tracking: fal.ai (from API). Replicate excluded (no pricing API).
+                if (nodeData.selectedModel?.provider === "fal" && nodeData.selectedModel?.pricing) {
+                  get().addIncurredCost(nodeData.selectedModel.pricing.amount);
+                }
+
                 // Auto-save image preview to generations folder if configured
                 const genPath = get().generationsPath;
                 if (genPath) {
@@ -1750,8 +1771,13 @@ export const useWorkflowStore = create<WorkflowStore>((set, get) => ({
           });
 
           // Track cost
-          const generationCost = calculateGenerationCost(nodeData.model, nodeData.resolution);
-          get().addIncurredCost(generationCost);
+          // Cost tracking: Gemini (hardcoded), fal.ai (from API). Replicate excluded (no pricing API).
+          if (nodeData.selectedModel?.provider === "fal" && nodeData.selectedModel?.pricing) {
+            get().addIncurredCost(nodeData.selectedModel.pricing.amount);
+          } else if (!nodeData.selectedModel || nodeData.selectedModel.provider === "gemini") {
+            const generationCost = calculateGenerationCost(nodeData.model, nodeData.resolution);
+            get().addIncurredCost(generationCost);
+          }
 
           // Auto-save to generations folder if configured
           const genPath = get().generationsPath;
@@ -2009,6 +2035,12 @@ export const useWorkflowStore = create<WorkflowStore>((set, get) => ({
             selectedVideoHistoryIndex: 0,
           });
 
+          // Track cost for video regeneration
+          // Cost tracking: fal.ai (from API). Replicate excluded (no pricing API).
+          if (nodeData.selectedModel?.provider === "fal" && nodeData.selectedModel?.pricing) {
+            get().addIncurredCost(nodeData.selectedModel.pricing.amount);
+          }
+
           // Auto-save video to generations folder if configured
           const genPath = get().generationsPath;
           if (genPath) {
@@ -2046,6 +2078,12 @@ export const useWorkflowStore = create<WorkflowStore>((set, get) => ({
             selectedVideoHistoryIndex: 0,
           });
 
+          // Track cost for video regeneration (image fallback case)
+          // Cost tracking: fal.ai (from API). Replicate excluded (no pricing API).
+          if (nodeData.selectedModel?.provider === "fal" && nodeData.selectedModel?.pricing) {
+            get().addIncurredCost(nodeData.selectedModel.pricing.amount);
+          }
+
           // Auto-save image preview to generations folder if configured
           const genPath = get().generationsPath;
           if (genPath) {

src/types/providers.ts

@@ -8,11 +8,18 @@
 // Provider Types for multi-provider support (image/video generation)
 export type ProviderType = "gemini" | "openai" | "replicate" | "fal";
 
+// Model pricing info (stored when model is selected)
+export interface SelectedModelPricing {
+  type: 'per-run' | 'per-second';
+  amount: number;
+}
+
 // Selected model for image/video generation nodes
 export interface SelectedModel {
   provider: ProviderType;
   modelId: string;
   displayName: string;
+  pricing?: SelectedModelPricing;  // Optional pricing info from provider API
 }
 
 export interface ProviderConfig {