Fix $0.00 cost on OpenRouter image generation models

Image-gen models are billed per-image/per-request, not at the plain
per-token prompt/completion rates ModelInfo.Pricing captures — so
token-based cost calculation was always near-zero for them regardless
of actual spend. Now requests OpenRouter's usage.include=true, decodes
the actual billed usage.cost, and prefers it over calculated cost via
a new resolveCost() helper (covers the dedicated Images API, regular
chat completions, streaming, and the tool-calling loop alike).

oAI/Providers/OpenRouterModels.swift

@@ -47,11 +47,18 @@ struct OpenRouterChatRequest: Codable {
     let modalities: [String]?
     let reasoning: ReasoningAPIConfig?
     let cacheControl: CacheControl?
+    let usage: UsageOptions?
 
     struct CacheControl: Codable {
         let type: String
     }
 
+    /// Requests OpenRouter to include the actual billed USD cost in the response's `usage`
+    /// object — needed for models priced outside plain per-token rates (e.g. per-image).
+    struct UsageOptions: Codable {
+        let include: Bool
+    }
+
     struct APIMessage: Codable {
         let role: String
         let content: MessageContent
@@ -141,6 +148,7 @@ struct OpenRouterChatRequest: Codable {
         case toolChoice = "tool_choice"
         case modalities
         case reasoning
+        case usage
         case cacheControl = "cache_control"
     }
 }
@@ -230,6 +238,9 @@ struct OpenRouterChatResponse: Codable {
         let completionTokens: Int
         let totalTokens: Int
         let promptTokensDetails: PromptTokensDetails?
+        /// Actual billed USD cost — only present when the request opted in via `usage.include`.
+        /// Needed for models priced outside plain per-token rates (e.g. per-image generation).
+        let cost: Double?
 
         struct PromptTokensDetails: Codable {
             let cachedTokens: Int?
@@ -246,6 +257,7 @@ struct OpenRouterChatResponse: Codable {
             case completionTokens = "completion_tokens"
             case totalTokens = "total_tokens"
             case promptTokensDetails = "prompt_tokens_details"
+            case cost
         }
     }
 }

oAI/Providers/OpenRouterProvider.swift

@@ -276,7 +276,8 @@ class OpenRouterProvider: AIProvider {
         var body: [String: Any] = [
             "model": model,
             "messages": messages,
-            "stream": false
+            "stream": false,
+            "usage": ["include": true]
         ]
         if let tools = tools {
             let toolsData = try JSONEncoder().encode(tools)
@@ -505,7 +506,8 @@ class OpenRouterProvider: AIProvider {
             toolChoice: request.tools != nil ? "auto" : nil,
             modalities: request.imageGeneration ? ["text", "image"] : nil,
             reasoning: reasoningConfig,
-            cacheControl: cacheControl
+            cacheControl: cacheControl,
+            usage: OpenRouterChatRequest.UsageOptions(include: true)
         )
     }
     
@@ -544,7 +546,8 @@ class OpenRouterProvider: AIProvider {
                     completionTokens: usage.completionTokens,
                     totalTokens: usage.totalTokens,
                     cacheCreationInputTokens: usage.promptTokensDetails?.cacheWriteTokens,
-                    cacheReadInputTokens: usage.promptTokensDetails?.cachedTokens
+                    cacheReadInputTokens: usage.promptTokensDetails?.cachedTokens,
+                    rawCostUSD: usage.cost
                 )
             },
             created: Date(timeIntervalSince1970: TimeInterval(apiResponse.created)),
@@ -585,7 +588,8 @@ class OpenRouterProvider: AIProvider {
                     completionTokens: usage.completionTokens,
                     totalTokens: usage.totalTokens,
                     cacheCreationInputTokens: usage.promptTokensDetails?.cacheWriteTokens,
-                    cacheReadInputTokens: usage.promptTokensDetails?.cachedTokens
+                    cacheReadInputTokens: usage.promptTokensDetails?.cachedTokens,
+                    rawCostUSD: usage.cost
                 )
             }
         )

oAI/ViewModels/ChatViewModel.swift

@@ -1150,8 +1150,7 @@ Don't narrate future actions ("Let me...") - just use the tools.
                         if let usage = response.usage {
                             messages[index].tokens = usage.completionTokens
                             if let model = selectedModel {
-                                let hasPricing = model.pricing.prompt > 0 || model.pricing.completion > 0
+                                let cost = Self.resolveCost(usage: usage, pricing: model.pricing)
-                                let cost: Double? = hasPricing ? Self.calculateCost(usage: usage, pricing: model.pricing) : nil
                                 messages[index].cost = cost
                                 sessionStats.addMessage(inputTokens: usage.promptTokens, outputTokens: usage.completionTokens, cost: cost)
                             }
@@ -1214,8 +1213,7 @@ Don't narrate future actions ("Let me...") - just use the tools.
                         if let usage = totalTokens {
                             messages[index].tokens = usage.completionTokens
                             if let model = selectedModel {
-                                let hasPricing = model.pricing.prompt > 0 || model.pricing.completion > 0
+                                let cost = Self.resolveCost(usage: usage, pricing: model.pricing)
-                                let cost: Double? = hasPricing ? Self.calculateCost(usage: usage, pricing: model.pricing) : nil
                                 messages[index].cost = cost
                                 sessionStats.addMessage(inputTokens: usage.promptTokens, outputTokens: usage.completionTokens, cost: cost)
                             }
@@ -1859,8 +1857,7 @@ Don't narrate future actions ("Let me...") - just use the tools.
                 if willAutoContinue && finalContent.isEmpty {
                     // Nothing worth showing yet — still record usage/cost for this turn.
                     if let usage = totalUsage, let model = selectedModel {
-                        let hasPricing = model.pricing.prompt > 0 || model.pricing.completion > 0
+                        let cost = Self.resolveCost(usage: usage, pricing: model.pricing)
-                        let cost: Double? = hasPricing ? Self.calculateCost(usage: usage, pricing: model.pricing) : nil
                         sessionStats.addMessage(
                             inputTokens: usage.promptTokens,
                             outputTokens: usage.completionTokens,
@@ -1884,8 +1881,7 @@ Don't narrate future actions ("Let me...") - just use the tools.
 
                     // Calculate cost
                     if let usage = totalUsage, let model = selectedModel {
-                        let hasPricing = model.pricing.prompt > 0 || model.pricing.completion > 0
+                        let cost = Self.resolveCost(usage: usage, pricing: model.pricing)
-                        let cost: Double? = hasPricing ? Self.calculateCost(usage: usage, pricing: model.pricing) : nil
                         if let index = messages.lastIndex(where: { $0.id == assistantMessage.id }) {
                             messages[index].cost = cost
                         }
@@ -2604,6 +2600,16 @@ Don't narrate future actions ("Let me...") - just use the tools.
         return inputCost + cacheReadCost + cacheWriteCost + outputCost
     }
 
+    /// Resolves a response's cost, preferring the provider's actual billed amount
+    /// (`usage.rawCostUSD` — e.g. OpenRouter's `usage.include` cost, needed for models priced
+    /// outside plain per-token rates like per-image generation) over token-based calculation.
+    /// Falls back to `nil` when neither the raw cost nor per-token pricing is available.
+    nonisolated static func resolveCost(usage: ChatResponse.Usage, pricing: ModelInfo.Pricing) -> Double? {
+        if let raw = usage.rawCostUSD { return raw }
+        guard pricing.prompt > 0 || pricing.completion > 0 else { return nil }
+        return calculateCost(usage: usage, pricing: pricing)
+    }
+
     /// Summarize a chunk of messages into a concise summary
     private func summarizeMessageChunk(_ messages: [Message]) async -> String? {
         guard let provider = providerRegistry.getProvider(for: currentProvider),

oAITests/ChatViewModelPureLogicTests.swift

@@ -82,6 +82,36 @@ struct ChatViewModelPureLogicTests {
         #expect(ChatViewModel.calculateCost(usage: usage, pricing: pricing) == 0.0)
     }
 
+    // MARK: - resolveCost
+
+    @Test("Raw provider-billed cost wins over token-based pricing when present")
+    func resolveCostPrefersRawCostUSD() {
+        let usage = ChatResponse.Usage(promptTokens: 1_000_000, completionTokens: 1_000_000, totalTokens: 2_000_000, rawCostUSD: 0.19)
+        let pricing = ModelInfo.Pricing(prompt: 3.0, completion: 15.0)
+        #expect(ChatViewModel.resolveCost(usage: usage, pricing: pricing) == 0.19)
+    }
+
+    @Test("Raw cost of zero is trusted, not treated as missing")
+    func resolveCostTrustsZeroRawCost() {
+        let usage = ChatResponse.Usage(promptTokens: 0, completionTokens: 0, totalTokens: 0, rawCostUSD: 0.0)
+        let pricing = ModelInfo.Pricing(prompt: 3.0, completion: 15.0)
+        #expect(ChatViewModel.resolveCost(usage: usage, pricing: pricing) == 0.0)
+    }
+
+    @Test("Falls back to token-based pricing when no raw cost is reported")
+    func resolveCostFallsBackToCalculation() {
+        let usage = ChatResponse.Usage(promptTokens: 1_000_000, completionTokens: 1_000_000, totalTokens: 2_000_000)
+        let pricing = ModelInfo.Pricing(prompt: 3.0, completion: 15.0)
+        #expect(ChatViewModel.resolveCost(usage: usage, pricing: pricing) == 18.0)
+    }
+
+    @Test("Returns nil when neither raw cost nor per-token pricing is available")
+    func resolveCostNilWhenNoDataAvailable() {
+        let usage = ChatResponse.Usage(promptTokens: 1_000_000, completionTokens: 1_000_000, totalTokens: 2_000_000)
+        let pricing = ModelInfo.Pricing(prompt: 0, completion: 0)
+        #expect(ChatViewModel.resolveCost(usage: usage, pricing: pricing) == nil)
+    }
+
     // MARK: - draftFingerprint
 
     @Test("Identical message content produces the same fingerprint")