feat: finally nailed down phases 1-4

MLXServerTests/Server/APIServerResponseResolutionTests.swift

@@ -0,0 +1,44 @@
+import MLXLMCommon
+import XCTest
+@testable import MLX_Server
+
+final class APIServerResponseResolutionTests: XCTestCase {
+    @MainActor
+    func testResolveAssistantResponseUsesFrameworkToolCalls() throws {
+        let frameworkToolCalls = [
+            ToolCall(function: ToolCall.Function(name: "weather", arguments: ["city": "Berlin"]))
+        ]
+
+        let resolved = APIServer.resolveAssistantResponse(
+            fullText: "I will call the tool.",
+            frameworkToolCalls: frameworkToolCalls,
+            tools: [mockWeatherTool]
+        )
+
+        XCTAssertEqual(resolved.finishReason, "tool_calls")
+        XCTAssertEqual(resolved.content, "I will call the tool.")
+        let toolCall = try XCTUnwrap(resolved.toolCalls?.first)
+        XCTAssertEqual(toolCall.function.name, "weather")
+        XCTAssertEqual(toolCall.function.arguments, #"{"city":"Berlin"}"#)
+    }
+
+    private var mockWeatherTool: APIToolDefinition {
+        APIToolDefinition(
+            type: "function",
+            function: APIFunctionDefinition(
+                name: "weather",
+                description: "Look up weather for a city.",
+                parameters: [
+                    "type": AnyCodable("object"),
+                    "properties": AnyCodable([
+                        "city": [
+                            "type": "string",
+                            "description": "City name"
+                        ]
+                    ]),
+                    "required": AnyCodable(["city"])
+                ]
+            )
+        )
+    }
+}