Fix DeepSeek cost attribution and pricing

internal/ai/cost/pricing.go

@@ -43,10 +43,13 @@ var providerPrices = map[string][]modelPrice{
 		{Pattern: "claude-sonnet*", InputUSDPerMTok: 3.00, OutputUSDPerMTok: 15.00},
 		{Pattern: "claude-haiku*", InputUSDPerMTok: 0.25, OutputUSDPerMTok: 1.25},
 	},
+	"deepseek": {
+		// DeepSeek docs include an "input cache hit" discount; this uses cache-miss rates for conservative estimates.
+		{Pattern: "deepseek-*", InputUSDPerMTok: 0.28, OutputUSDPerMTok: 0.42},
+	},
 	"ollama": {
 		{Pattern: "*", InputUSDPerMTok: 0, OutputUSDPerMTok: 0},
 	},
-	// deepseek pricing intentionally omitted until stable public pricing is confirmed.
 }
 
 func lookupPrice(provider, model string) (TokenPrice, bool) {

internal/ai/cost/store.go

@@ -122,8 +122,9 @@ func (s *Store) GetSummary(days int) Summary {
 	var totalInput, totalOutput int64
 
 	for _, e := range events {
-		provider := e.Provider
+		provider := strings.ToLower(strings.TrimSpace(e.Provider))
 		model := normalizeModel(provider, e.RequestModel, e.ResponseModel)
+		provider, model = inferProviderAndModel(provider, model)
 
 		k := pmKey{provider: provider, model: model}
 		pm := pmTotals[k]
@@ -278,6 +279,19 @@ func normalizeModel(provider, requestModel, responseModel string) string {
 	return ""
 }
 
+func inferProviderAndModel(provider, model string) (string, string) {
+	if provider == "openai" {
+		parts := strings.SplitN(strings.TrimSpace(model), ":", 2)
+		if len(parts) == 2 && strings.ToLower(parts[0]) == "deepseek" {
+			return "deepseek", parts[1]
+		}
+		if strings.HasPrefix(strings.ToLower(strings.TrimSpace(model)), "deepseek") {
+			return "deepseek", model
+		}
+	}
+	return provider, model
+}
+
 // ProviderModelSummary is a rollup for a provider/model pair.
 type ProviderModelSummary struct {
 	Provider     string  `json:"provider"`

internal/ai/cost/store_test.go

@@ -130,7 +130,11 @@ func TestEstimateUSDKnownAndUnknownModels(t *testing.T) {
 	}
 
 	usd, ok, _ = EstimateUSD("deepseek", "deepseek-reasoner", 1_000_000, 1_000_000)
-	if ok || usd != 0 {
+	if !ok {
-		t.Fatalf("expected deepseek pricing to be unknown, got ok=%v usd=%.4f", ok, usd)
+		t.Fatalf("expected deepseek pricing to be known for deepseek-reasoner")
+	}
+	expected = 0.70 // 1M input * $0.28 + 1M output * $0.42
+	if math.Abs(usd-expected) > 0.0001 {
+		t.Fatalf("expected usd %.4f, got %.4f", expected, usd)
 	}
 }

internal/ai/service.go

@@ -1002,9 +1002,13 @@ Always execute the commands rather than telling the user how to do it.`
 		}
 
 		if costStore != nil {
+			providerName, _ := config.ParseModelString(modelString)
+			if providerName == "" {
+				providerName = provider.Name()
+			}
 			costStore.Record(cost.UsageEvent{
 				Timestamp:     time.Now(),
-				Provider:      provider.Name(),
+				Provider:      providerName,
 				RequestModel:  modelString,
 				ResponseModel: resp.Model,
 				UseCase:       req.UseCase,
@@ -1189,9 +1193,13 @@ Always execute the commands rather than telling the user how to do it.`
 		}
 
 		if costStore != nil {
+			providerName, _ := config.ParseModelString(modelString)
+			if providerName == "" {
+				providerName = provider.Name()
+			}
 			costStore.Record(cost.UsageEvent{
 				Timestamp:     time.Now(),
-				Provider:      provider.Name(),
+				Provider:      providerName,
 				RequestModel:  modelString,
 				ResponseModel: resp.Model,
 				UseCase:       req.UseCase,