fix: warn on unknown model pricing lookups

Add console.warn when calculateMessageCost encounters an unknown model,
so pricing.json gaps are visible rather than silently returning $0.
Update tests to expect the warning.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/shared/utils/pricing.ts

@@ -73,7 +73,12 @@ export function calculateMessageCost(
   cacheCreationTokens: number
 ): number {
   const pricing = getPricing(modelName);
-  if (!pricing) return 0;
+  if (!pricing) {
+    if (inputTokens > 0 || outputTokens > 0) {
+      console.warn(`[pricing] No pricing data for model "${modelName}", cost will be $0`);
+    }
+    return 0;
+  }
 
   const inputCost = calculateTieredCost(
     inputTokens,

test/main/utils/costCalculation.test.ts

@@ -2,7 +2,7 @@
  * Tests for cost calculation in jsonl.ts
  */
 
-import { describe, it, expect } from 'vitest';
+import { describe, it, expect, vi } from 'vitest';
 import { calculateMetrics } from '@main/utils/jsonl';
 import type { ParsedMessage } from '@main/types';
 
@@ -84,6 +84,7 @@ describe('Cost Calculation', () => {
     });
 
     it('should return 0 cost when model pricing not found', () => {
+      const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
       const messages: ParsedMessage[] = [
         {
           type: 'assistant',
@@ -103,6 +104,7 @@ describe('Cost Calculation', () => {
 
       const metrics = calculateMetrics(messages);
       expect(metrics.costUsd).toBe(0);
+      warnSpy.mockRestore();
     });
   });
 

test/shared/utils/pricing.test.ts

@@ -1,4 +1,4 @@
-import { describe, it, expect } from 'vitest';
+import { describe, it, expect, vi } from 'vitest';
 import {
   getPricing,
   calculateTieredCost,
@@ -55,8 +55,13 @@ describe('Shared Pricing Module', () => {
     });
 
     it('should return 0 for unknown models', () => {
+      const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
       const cost = calculateMessageCost('unknown-model', 1000, 500, 0, 0);
       expect(cost).toBe(0);
+      expect(warnSpy).toHaveBeenCalledWith(
+        '[pricing] No pricing data for model "unknown-model", cost will be $0'
+      );
+      warnSpy.mockRestore();
     });
 
     it('should include cache token costs', () => {