fix(pricing): handle date-stamped 4.6 thinking model IDs

src/web-server/model-pricing.ts

@@ -734,7 +734,7 @@ const UNKNOWN_MODEL_PRICING: ModelPricing = {
 
 /**
  * Normalize model name for matching
- * Handles variations like provider prefixes, case differences, and date suffixes
+ * Handles variations like provider prefixes and case differences
  */
 function normalizeModelName(model: string): string {
   // Remove provider prefixes (e.g., "anthropic/claude-..." -> "claude-...")
@@ -747,10 +747,14 @@ function normalizeModelName(model: string): string {
 
 /**
  * Strip trailing date suffix from model name (e.g., "-20260101")
- * Only strips 8-digit YYYYMMDD suffixes at the end of the string.
+ * Claude session IDs can place dates either at the end or before "-thinking".
  */
 function stripDateSuffix(model: string): string {
-  return model.replace(/-\d{8}$/, '');
+  if (!model.startsWith('claude-')) {
+    return model;
+  }
+
+  return model.replace(/-\d{8}(?=-thinking(?:$|:))/g, '').replace(/-\d{8}(?=$|:)/g, '');
 }
 
 const NORMALIZED_PRICING_REGISTRY: Record<string, ModelPricing> = Object.entries(

tests/unit/model-pricing.test.ts

@@ -120,6 +120,18 @@ describe('model-pricing', () => {
       expect(opus46.inputPerMillion).toBe(5.0);
       expect(opus46.outputPerMillion).toBe(25.0);
     });
+
+    it('should match date-stamped thinking Claude Opus 4.6 to correct pricing', () => {
+      const opus46 = getModelPricing('claude-opus-4-6-20260101-thinking');
+      expect(opus46.inputPerMillion).toBe(5.0);
+      expect(opus46.outputPerMillion).toBe(25.0);
+    });
+
+    it('should match provider-prefixed date-stamped thinking model to correct pricing', () => {
+      const opus46 = getModelPricing('anthropic/claude-opus-4-6-20260101-thinking');
+      expect(opus46.inputPerMillion).toBe(5.0);
+      expect(opus46.outputPerMillion).toBe(25.0);
+    });
   });
 
   describe('calculateCost', () => {
@@ -209,6 +221,10 @@ describe('model-pricing', () => {
       expect(hasCustomPricing('qwen3-coder')).toBe(true);
     });
 
+    it('should not treat date-stamped non-Claude IDs as deterministic aliases', () => {
+      expect(hasCustomPricing('qwen3-32b-20260101')).toBe(false);
+    });
+
     it('should return false for unknown models', () => {
       expect(hasCustomPricing('unknown-model-xyz')).toBe(false);
     });