ayman3000 · ayman3000 · Jul 27, 2026 · Jul 27, 2026
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -6,9 +6,13 @@ All notable changes to LLMProviderKit will be documented in this file.
 
 ### Fixed
 - Decode streaming response lines from complete UTF-8 byte buffers instead of byte-by-byte Unicode scalars, preserving multi-byte characters such as Arabic, CJK, accents, and emoji.
+- Send a valid `anthropic-version` header (`2023-06-01`) instead of the branding string, which Anthropic rejected with HTTP 400; moved branding to `User-Agent`.
+- Send Gemini tool results (`functionResponse` parts) in a `user` turn instead of `model`; Gemini only accepts `user`/`model` roles and mishandled tool results sent as `model`.
 
 ### Added
+- Latest curated models: OpenAI GPT-5.6 (`gpt-5.6`), Gemini 3.6 Flash (`gemini-3.6-flash`) and Gemini 3.5 Flash-Lite (`gemini-3.5-flash-lite`), and Anthropic Opus 4.7 / Opus 4.6. Gemini's default preset model is now Gemini 3.6 Flash.
 - Regression coverage for non-ASCII streaming text.
+- Regression coverage for the Anthropic version header and Gemini tool-result role.
 - MIT license file.
 
 ## 0.1.0-alpha.4 - 2026-07-06

diff --git a/Sources/LLMProviderKitAnthropic/AnthropicProvider.swift b/Sources/LLMProviderKitAnthropic/AnthropicProvider.swift
@@ -28,7 +28,10 @@ public struct AnthropicProvider: LLMProvider {
         if let apiKey = configuration.apiKey {
             urlRequest.setValue(apiKey, forHTTPHeaderField: "x-api-key")
         }
-        urlRequest.setValue("LLMProviderKit/1.0", forHTTPHeaderField: "anthropic-version")
+        // Anthropic requires a dated API version string; an arbitrary value is rejected
+        // with HTTP 400 "invalid anthropic-version".
+        urlRequest.setValue("2023-06-01", forHTTPHeaderField: "anthropic-version")
+        urlRequest.setValue("LLMProviderKit/1.0", forHTTPHeaderField: "User-Agent")
 
         let maxTokens = request.maxTokens ?? 4096
 
@@ -405,6 +408,8 @@ public enum AnthropicModel {
     // Current models
     public static let fable5 = "claude-fable-5"
     public static let opus48 = "claude-opus-4-8"
+    public static let opus47 = "claude-opus-4-7"
+    public static let opus46 = "claude-opus-4-6"
     public static let sonnet46 = "claude-sonnet-4-6"
     public static let haiku45 = "claude-haiku-4-5-20251001"
     // Legacy
@@ -440,6 +445,24 @@ extension AnthropicProvider {
             categories: [.text, .vision, .multimodal],
             releaseStage: .stable
         ),
+        LLMModelInfo(
+            id: AnthropicModel.opus47,
+            providerName: name,
+            displayName: "Claude Opus 4.7",
+            contextWindow: 1_000_000,
+            capabilities: [.chat, .textGeneration, .streaming, .reasoning, .tools, .vision, .imageInput, .structuredOutput],
+            categories: [.text, .vision, .multimodal],
+            releaseStage: .stable
+        ),
+        LLMModelInfo(
+            id: AnthropicModel.opus46,
+            providerName: name,
+            displayName: "Claude Opus 4.6",
+            contextWindow: 1_000_000,
+            capabilities: [.chat, .textGeneration, .streaming, .reasoning, .tools, .vision, .imageInput, .structuredOutput],
+            categories: [.text, .vision, .multimodal],
+            releaseStage: .stable
+        ),
         LLMModelInfo(
             id: AnthropicModel.sonnet46,
             providerName: name,

diff --git a/Sources/LLMProviderKitGemini/GeminiProvider.swift b/Sources/LLMProviderKitGemini/GeminiProvider.swift
@@ -339,7 +339,10 @@ public struct GeminiProvider: LLMProvider {
         case .system: return "user"
         case .user: return "user"
         case .assistant: return "model"
-        case .tool: return "model" // Gemini uses "model" role for function responses
+        // Gemini only accepts "user" and "model" roles in `contents`. Function
+        // responses (`functionResponse` parts) must be sent in a "user" turn;
+        // sending them as "model" is rejected/mishandled by the API.
+        case .tool: return "user"
         }
     }
 
@@ -374,7 +377,7 @@ public struct GeminiProvider: LLMProvider {
         // Keep this conservative for live metadata. Curated records can add
         // reasoning for known flagship non-Pro IDs, but a broad `contains("3.")`
         // marks every Gemini 3.x Flash/Lite model as reasoning-capable.
-        modelID.contains("-pro") || modelID.hasPrefix("gemini-3.5-")
+        modelID.contains("-pro") || modelID.hasPrefix("gemini-3.5-") || modelID.hasPrefix("gemini-3.6-")
     }
 
     private static func categories(for model: GeminiModelsResponse.Model, cleanId: String) -> Set<LLMModelCategory> {
@@ -498,7 +501,9 @@ private struct GeminiModelsResponse: Decodable {
 
 public enum GeminiModel {
     // Gemini 3.x family (current)
+    public static let flash36 = "gemini-3.6-flash"
     public static let flash35 = "gemini-3.5-flash"
+    public static let flashLite35 = "gemini-3.5-flash-lite"
     public static let flashLite31 = "gemini-3.1-flash-lite"
     public static let pro31 = "gemini-3.1-pro"
     public static let flash30 = "gemini-3-flash"
@@ -512,6 +517,15 @@ public enum GeminiModel {
 
 extension GeminiProvider {
     public static let curatedModels: [LLMModelInfo] = [
+        LLMModelInfo(
+            id: GeminiModel.flash36,
+            providerName: name,
+            displayName: "Gemini 3.6 Flash",
+            capabilities: [.chat, .textGeneration, .streaming, .tools, .vision, .imageInput, .reasoning, .structuredOutput],
+            categories: [.text, .vision, .multimodal],
+            releaseStage: .stable,
+            notes: "Latest Gemini Flash — stronger agentic/multimodal performance at lower cost than 3.5 Flash."
+        ),
         LLMModelInfo(
             id: GeminiModel.flash35,
             providerName: name,
@@ -521,6 +535,15 @@ extension GeminiProvider {
             releaseStage: .stable,
             notes: "Stable Gemini 3.x model for agentic and coding workloads."
         ),
+        LLMModelInfo(
+            id: GeminiModel.flashLite35,
+            providerName: name,
+            displayName: "Gemini 3.5 Flash-Lite",
+            capabilities: [.chat, .textGeneration, .streaming, .tools, .vision, .imageInput, .structuredOutput],
+            categories: [.text, .vision, .multimodal],
+            releaseStage: .stable,
+            notes: "Fastest, lowest-cost model in the 3.5 family for high-throughput execution."
+        ),
         LLMModelInfo(
             id: GeminiModel.flashLite31,
             providerName: name,
@@ -573,7 +596,7 @@ extension GeminiProvider {
         ),
     ]
 
-    public static func gemini(apiKey: String, model: String = GeminiModel.flash35) -> LLMProviderConfiguration {
+    public static func gemini(apiKey: String, model: String = GeminiModel.flash36) -> LLMProviderConfiguration {
         LLMProviderConfiguration(
             name: name,
             baseURL: URL(string: "https://generativelanguage.googleapis.com/v1beta")!,

diff --git a/Sources/LLMProviderKitOpenAI/OpenAIProvider.swift b/Sources/LLMProviderKitOpenAI/OpenAIProvider.swift
@@ -291,7 +291,9 @@ private struct OpenAIModelsResponse: Decodable {
 // MARK: - Model constants
 
 public enum OpenAIModel {
-    // GPT-5.5 family (current flagship)
+    // GPT-5.6 family (current flagship). `gpt-5.6` is an alias that routes to GPT-5.6 Sol.
+    public static let gpt56 = "gpt-5.6"
+    // GPT-5.5 family
     public static let gpt55 = "gpt-5.5"
     // GPT-5.4 family
     public static let gpt54 = "gpt-5.4"
@@ -305,6 +307,16 @@ public enum OpenAIModel {
 
 extension OpenAIProvider {
     public static let curatedModels: [LLMModelInfo] = [
+        LLMModelInfo(
+            id: OpenAIModel.gpt56,
+            providerName: name,
+            displayName: "GPT-5.6",
+            contextWindow: 1_000_000,
+            capabilities: [.chat, .textGeneration, .streaming, .tools, .vision, .imageInput, .reasoning, .structuredOutput],
+            categories: [.text, .vision, .multimodal],
+            releaseStage: .stable,
+            notes: "Current flagship (alias for GPT-5.6 Sol) — most intelligent and token-efficient for complex work."
+        ),
         LLMModelInfo(
             id: OpenAIModel.gpt55,
             providerName: name,
@@ -313,7 +325,7 @@ extension OpenAIProvider {
             capabilities: [.chat, .textGeneration, .streaming, .tools, .vision, .imageInput, .reasoning, .structuredOutput],
             categories: [.text, .vision, .multimodal],
             releaseStage: .stable,
-            notes: "Flagship model for complex reasoning and coding."
+            notes: "Previous flagship for complex reasoning and coding."
         ),
         LLMModelInfo(
             id: OpenAIModel.gpt54,

diff --git a/Tests/LLMProviderKitTests/LLMKitTests.swift b/Tests/LLMProviderKitTests/LLMKitTests.swift
@@ -701,6 +701,41 @@ extension ProviderTests {
         #expect(firstMsg["content"] is String)
     }
 
+    @Test func anthropicSendsValidVersionHeader() async throws {
+        let provider = AnthropicProvider(configuration: AnthropicProvider.anthropic(apiKey: "test", model: "claude-3-5-sonnet-20241022"))
+        let request = LLMRequest(model: "claude-3-5-sonnet-20241022", messages: [.user("Hi")])
+        let urlRequest = try provider.prepareRequest(request, stream: false)
+
+        // Anthropic requires a dated version string; the branding string belongs in User-Agent.
+        #expect(urlRequest.value(forHTTPHeaderField: "anthropic-version") == "2023-06-01")
+        #expect(urlRequest.value(forHTTPHeaderField: "anthropic-version") != "LLMProviderKit/1.0")
+    }
+
+    @Test func geminiSendsToolResultsAsUserRole() async throws {
+        let provider = GeminiProvider(configuration: GeminiProvider.gemini(apiKey: "test", model: "gemini-2.5-flash"))
+        let request = LLMRequest(
+            model: "gemini-2.5-flash",
+            messages: [
+                .user("What time is it?"),
+                .assistant(content: "", toolCalls: [
+                    LLMToolCall(id: "call_1", name: "current_datetime", arguments: "{}")
+                ]),
+                .tool("{\"result\":\"noon\"}", toolCallId: "current_datetime")
+            ]
+        )
+
+        let body = try #require(provider.prepareRequest(request, stream: false).httpBody)
+        let json = try #require(JSONSerialization.jsonObject(with: body) as? [String: Any])
+        let contents = try #require(json["contents"] as? [[String: Any]])
+
+        // The turn carrying the functionResponse part must use the "user" role.
+        let functionResponseTurn = try #require(contents.first { turn in
+            guard let parts = turn["parts"] as? [[String: Any]] else { return false }
+            return parts.contains { $0["functionResponse"] != nil }
+        })
+        #expect(functionResponseTurn["role"] as? String == "user")
+    }
+
     @Test func ollamaAssistantToolCallsSerializeArgumentsAsJSONObject() async throws {
         let ollama = OllamaProvider(configuration: OllamaProvider.local(model: "qwen3:0.6b"))
         let request = LLMRequest(