fix: resolve $0.00 session costs in tapes deck

pkg/deck/pricing.go

@@ -34,6 +34,7 @@ func DefaultPricing() PricingTable {
 		"claude-sonnet-4":   {Input: 3.00, Output: 15.00, CacheRead: 0.30, CacheWrite: 3.75},
 		"claude-sonnet-3.7": {Input: 3.00, Output: 15.00, CacheRead: 0.30, CacheWrite: 3.75},
 		"claude-haiku-4.5":  {Input: 1.00, Output: 5.00, CacheRead: 0.10, CacheWrite: 1.25},
+		"claude-haiku-4.6":  {Input: 1.00, Output: 5.00, CacheRead: 0.10, CacheWrite: 1.25},
 		"claude-3.5-sonnet": {Input: 3.00, Output: 15.00, CacheRead: 0.30, CacheWrite: 3.75},
 		"claude-3.5-haiku":  {Input: 0.80, Output: 4.00, CacheRead: 0.08, CacheWrite: 1.00},
 		"claude-3-opus":     {Input: 15.00, Output: 75.00, CacheRead: 1.50, CacheWrite: 18.75},

pkg/deck/pricing_test.go

@@ -193,6 +193,19 @@ var _ = Describe("PricingForModel", func() {
 		Expect(p.CacheRead).To(Equal(0.14))
 	})
 
+	It("resolves claude-haiku-4.6", func() {
+		p, ok := PricingForModel(pricing, "claude-haiku-4.6")
+		Expect(ok).To(BeTrue())
+		Expect(p.Input).To(Equal(1.00))
+		Expect(p.Output).To(Equal(5.00))
+	})
+
+	It("resolves claude-haiku-4-6 with date suffix", func() {
+		p, ok := PricingForModel(pricing, "claude-haiku-4-6-20260219")
+		Expect(ok).To(BeTrue())
+		Expect(p.Input).To(Equal(1.00))
+	})
+
 	It("returns false for unknown models", func() {
 		_, ok := PricingForModel(pricing, "totally-unknown-model")
 		Expect(ok).To(BeFalse())

pkg/deck/query.go

@@ -759,6 +759,7 @@ func (q *Query) buildSessionSummaryFromNodes(nodes []*ent.Node) (SessionSummary,
 
 	hasToolError := false
 	hasGitActivity := false
+	var lastModel string
 	for _, n := range nodes {
 		blocks, _ := parseContentBlocks(n.Content)
 		toolCalls += countToolCalls(blocks)
@@ -782,9 +783,13 @@ func (q *Query) buildSessionSummaryFromNodes(nodes []*ent.Node) (SessionSummary,
 		outputTokens += t.Output
 
 		model := normalizeModel(n.Model)
+		if model == "" {
+			model = lastModel
+		}
 		if model == "" {
 			continue
 		}
+		lastModel = model
 
 		pricing, ok := PricingForModel(q.pricing, model)
 		if !ok {

pkg/deck/query_test.go

@@ -71,6 +71,66 @@ var _ = Describe("Session labels", func() {
 	})
 })
 
+var _ = Describe("Empty-model cost fallback", func() {
+	intPtr := func(v int) *int { return &v }
+
+	It("uses last-seen model for response nodes with empty model", func() {
+		pricing := DefaultPricing()
+		q := &Query{pricing: pricing}
+
+		nodes := []*ent.Node{
+			{
+				ID:    "node-1",
+				Role:  "user",
+				Model: "claude-opus-4-6-20260219",
+				Content: []map[string]any{{
+					"text": "Hello",
+					"type": "text",
+				}},
+				PromptTokens:     intPtr(100),
+				CompletionTokens: intPtr(0),
+			},
+			{
+				ID:               "node-2",
+				Role:             "assistant",
+				Model:            "", // empty model — the bug
+				Content:          []map[string]any{{"text": "Hi!", "type": "text"}},
+				PromptTokens:     intPtr(0),
+				CompletionTokens: intPtr(50),
+			},
+		}
+
+		summary, modelCosts, _, err := q.buildSessionSummaryFromNodes(nodes)
+		Expect(err).NotTo(HaveOccurred())
+
+		// The assistant node should have been costed using the user node's model
+		Expect(summary.TotalCost).To(BeNumerically(">", 0))
+		Expect(modelCosts).To(HaveKey("claude-opus-4.6"))
+		cost := modelCosts["claude-opus-4.6"]
+		Expect(cost.OutputTokens).To(Equal(int64(50)))
+		Expect(cost.TotalCost).To(BeNumerically(">", 0))
+	})
+
+	It("skips nodes when no model has been seen yet", func() {
+		pricing := DefaultPricing()
+		q := &Query{pricing: pricing}
+
+		nodes := []*ent.Node{
+			{
+				ID:               "node-1",
+				Role:             "assistant",
+				Model:            "", // no model, and no prior model
+				Content:          []map[string]any{{"text": "orphan", "type": "text"}},
+				CompletionTokens: intPtr(50),
+			},
+		}
+
+		_, modelCosts, _, err := q.buildSessionSummaryFromNodes(nodes)
+		Expect(err).NotTo(HaveOccurred())
+		Expect(modelCosts).To(BeEmpty())
+	})
+})
+
 var _ = Describe("Analytics helper functions", func() {
 	Describe("buildDurationBuckets", func() {
 		It("distributes sessions into correct duration buckets", func() {

proxy/proxy.go

@@ -559,6 +559,9 @@ func (p *Proxy) enqueueStreamedResponse(allChunks [][]byte, fullContent string,
 
 		finalResp := p.reconstructStreamedResponse(allChunks, fullContent, streamUsage, meta, prov)
 		if finalResp != nil {
+			if finalResp.Model == "" && parsedReq.Model != "" {
+				finalResp.Model = parsedReq.Model
+			}
 			p.workerPool.Enqueue(worker.Job{
 				Provider:  prov.Name(),
 				AgentName: agentName,