feat: finally nailed down phases 1-4

MLXServerTests/Server/ToolCallParserTests.swift

@@ -0,0 +1,47 @@
+import XCTest
+@testable import MLX_Server
+
+final class ToolCallParserTests: XCTestCase {
+    func testParseGemmaToolCodeBlockExtractsToolCallAndStripsFence() throws {
+        let tools = [mockWeatherTool]
+        let text = "Before\n```tool_code\nweather(city=\"Berlin\")\n```\nAfter"
+
+        let parsed = ToolCallParser.parse(text: text, tools: tools)
+
+        XCTAssertEqual(parsed.0, "Before\n\nAfter")
+        let toolCall = try XCTUnwrap(parsed.1.first)
+        XCTAssertEqual(toolCall.name, "weather")
+        XCTAssertEqual(toolCall.arguments, #"{"city":"Berlin"}"#)
+    }
+
+    func testParseQwenToolCallTagExtractsJSONPayloadAndStripsTag() throws {
+        let text = "<tool_call>{\"name\":\"weather\",\"arguments\":{\"city\":\"Paris\"}}</tool_call>"
+
+        let parsed = ToolCallParser.parse(text: text, tools: [mockWeatherTool])
+
+        XCTAssertEqual(parsed.0, "")
+        let toolCall = try XCTUnwrap(parsed.1.first)
+        XCTAssertEqual(toolCall.name, "weather")
+        XCTAssertEqual(toolCall.arguments, #"{"city":"Paris"}"#)
+    }
+
+    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"])
+                ]
+            )
+        )
+    }
+}