Demonstrate API compatibility

README.md

@@ -1,6 +1,6 @@
 # AnyLanguageModel
 
-A Swift package that provides an API-compatible, drop-in replacement for 
+A Swift package that provides an API-compatible replacement for 
 [Apple's Foundation Models framework](https://developer.apple.com/documentation/FoundationModels)
 with support for custom language model providers.
 
@@ -63,12 +63,47 @@ dependencies: [
 
 ## Usage
 
+AnyLanguageModel is a drop-in replacement for Apple's Foundation Models framework.
+All you need to do is change your import statement:
+
+```diff
+- import FoundationModels
++ import AnyLanguageModel
+```
+
+```swift
+struct WeatherTool: Tool {
+    let name = "getWeather"
+    let description = "Retrieve the latest weather information for a city"
+
+    @Generable
+    struct Arguments {
+        @Guide(description: "The city to fetch the weather for")
+        var city: String
+    }
+
+    func call(arguments: Arguments) async throws -> String {
+        "The weather in \(arguments.city) is sunny and 72°F / 23°C"
+    }
+}
+
+let model = SystemLanguageModel.default
+let session = LanguageModelSession(model: model, tools: [WeatherTool()])
+
+let response = try await session.respond {
+    Prompt("How's the weather in Cupertino?")
+}
+print(response.content)
+```
+
+Here's an example using all of the available language model providers:
+
 ```swift
 import AnyLanguageModel
 
 // Core functionality (always available)
 var models: [(any LanguageModel)] = [
-    SystemLanguageModel(), // Apple Foundation Models
+    SystemLanguageModel.default,
     OllamaLanguageModel(model: "qwen3") // `ollama pull qwen3:0.6b`
     AnthropicLanguageModel(
         apiKey: ProcessInfo.processInfo.environment["ANTHROPIC_API_KEY"]!,
@@ -93,24 +128,9 @@ models.append(MLXLanguageModel(modelId: "mlx-community/Qwen3-0.6B-4bit"))
 models.append(LlamaLanguageModel(modelPath: "/path/to/model.gguf"))
 #endif
 
-struct WeatherTool: Tool {
-    let name = "getWeather"
-    let description = "Retrieve the latest weather information for a city"
-
-    @Generable
-    struct Arguments {
-        @Guide(description: "The city to fetch the weather for")
-        var city: String
-    }
-
-    func call(arguments: Arguments) async throws -> String {
-        "The weather in \(arguments.city) is sunny and 72°F / 23°C"
-    }
-}
-
 for model in models {
     let session = LanguageModelSession(model: model, tools: [WeatherTool()])
-    let response = try await session.respond(to: "What's the weather in Cupertino?")
+    let response = try await session.respond(to: "How's the weather in Cupertino?")
     print(response.text) // "It's sunny and 72°F in Cupertino"
 }
 ```

Tests/AnyLanguageModelTests/APICompatibilityAnyLanguageModelTests.swift

@@ -0,0 +1,31 @@
+import Testing
+
+#if canImport(FoundationModels)
+    import AnyLanguageModel
+
+    @available(macOS 26.0, *)
+    @Test("AnyLanguageModel Drop-In Compatibility", .enabled(if: SystemLanguageModel.default.isAvailable))
+    func anyLanguageModelCompatibility() async throws {
+        let model = SystemLanguageModel.default
+        let session = LanguageModelSession(
+            model: model,
+            instructions: Instructions("You are a helpful assistant.")
+        )
+
+        let options = GenerationOptions(temperature: 0.7)
+        let response = try await session.respond(options: options) {
+            Prompt("Say 'Hello'")
+        }
+        #expect(!response.content.isEmpty)
+
+        let stream = session.streamResponse {
+            Prompt("Count to 3")
+        }
+        var hasSnapshots = false
+        for try await _ in stream {
+            hasSnapshots = true
+            break
+        }
+        #expect(hasSnapshots)
+    }
+#endif

Tests/AnyLanguageModelTests/APICompatibilityFoundationModelsTests.swift

@@ -0,0 +1,31 @@
+import Testing
+
+#if canImport(FoundationModels)
+    import FoundationModels
+
+    @available(macOS 26.0, *)
+    @Test("FoundationModels Drop-In Compatibility", .enabled(if: SystemLanguageModel.default.isAvailable))
+    func foundationModelsCompatibility() async throws {
+        let model = SystemLanguageModel.default
+        let session = LanguageModelSession(
+            model: model,
+            instructions: Instructions("You are a helpful assistant.")
+        )
+
+        let options = GenerationOptions(temperature: 0.7)
+        let response = try await session.respond(options: options) {
+            Prompt("Say 'Hello'")
+        }
+        #expect(!response.content.isEmpty)
+
+        let stream = session.streamResponse {
+            Prompt("Count to 3")
+        }
+        var hasSnapshots = false
+        for try await _ in stream {
+            hasSnapshots = true
+            break
+        }
+        #expect(hasSnapshots)
+    }
+#endif

Tests/AnyLanguageModelTests/AnthropicLanguageModelTests.swift

@@ -90,7 +90,7 @@ struct AnthropicLanguageModelTests {
         let weatherTool = WeatherTool()
         let session = LanguageModelSession(model: model, tools: [weatherTool])
 
-        let response = try await session.respond(to: "What's the weather in San Francisco?")
+        let response = try await session.respond(to: "How's the weather in San Francisco?")
 
         var foundToolOutput = false
         for case let .toolOutput(toolOutput) in response.transcriptEntries {

Tests/AnyLanguageModelTests/MLXLanguageModelTests.swift

@@ -64,7 +64,7 @@ import Testing
                 instructions: "You are a helpful assistant. Use available tools when needed."
             )
 
-            let response = try await session.respond(to: "What's the weather in San Francisco?")
+            let response = try await session.respond(to: "How's the weather in San Francisco?")
 
             var foundToolOutput = false
             for case let .toolOutput(toolOutput) in response.transcriptEntries {

Tests/AnyLanguageModelTests/OllamaLanguageModelTests.swift

@@ -85,7 +85,7 @@ struct OllamaLanguageModelTests {
         let weatherTool = spy(on: WeatherTool())
         let session = LanguageModelSession(model: model, tools: [weatherTool])
 
-        let response = try await session.respond(to: "What's the weather in San Francisco?")
+        let response = try await session.respond(to: "How's the weather in San Francisco?")
 
         var foundToolOutput = false
         for case let .toolOutput(toolOutput) in response.transcriptEntries {

Tests/AnyLanguageModelTests/OpenAILanguageModelTests.swift

@@ -104,7 +104,7 @@ struct OpenAILanguageModelTests {
             let weatherTool = WeatherTool()
             let session = LanguageModelSession(model: model, tools: [weatherTool])
 
-            let response = try await session.respond(to: "What's the weather in San Francisco?")
+            let response = try await session.respond(to: "How's the weather in San Francisco?")
 
             var foundToolOutput = false
             for case let .toolOutput(toolOutput) in response.transcriptEntries {
@@ -196,7 +196,7 @@ struct OpenAILanguageModelTests {
             let weatherTool = WeatherTool()
             let session = LanguageModelSession(model: model, tools: [weatherTool])
 
-            let response = try await session.respond(to: "What's the weather in San Francisco?")
+            let response = try await session.respond(to: "How's the weather in San Francisco?")
 
             var foundToolOutput = false
             for case let .toolOutput(toolOutput) in response.transcriptEntries {