fix(mac): harden gateway frame decoding

apps/macos/Tests/ClawdisIPCTests/GatewayFrameDecodeTests.swift

@@ -28,4 +28,71 @@ import Testing
         #expect(payload?["count"]?.value as? Int == 1)
         #expect(evt.seq == 7)
     }
+
+    @Test func decodesRequestFrameWithNestedParams() throws {
+        let json = """
+        {
+          "type": "req",
+          "id": "1",
+          "method": "agent.send",
+          "params": {
+            "text": "hi",
+            "items": [1, null, {"ok": true}],
+            "meta": { "count": 2 }
+          }
+        }
+        """
+
+        let frame = try JSONDecoder().decode(GatewayFrame.self, from: Data(json.utf8))
+
+        #expect({
+            if case .req = frame { true } else { false }
+        }(), "expected .req frame")
+
+        guard case let .req(req) = frame else {
+            return
+        }
+
+        let params = req.params?.value as? [String: AnyCodable]
+        #expect(params?["text"]?.value as? String == "hi")
+
+        let items = params?["items"]?.value as? [AnyCodable]
+        #expect(items?.count == 3)
+        #expect(items?[0].value as? Int == 1)
+        #expect(items?[1].value is NSNull)
+
+        let item2 = items?[2].value as? [String: AnyCodable]
+        #expect(item2?["ok"]?.value as? Bool == true)
+
+        let meta = params?["meta"]?.value as? [String: AnyCodable]
+        #expect(meta?["count"]?.value as? Int == 2)
+    }
+
+    @Test func decodesUnknownFrameAndPreservesRaw() throws {
+        let json = """
+        {
+          "type": "made-up",
+          "foo": "bar",
+          "count": 1,
+          "nested": { "ok": true }
+        }
+        """
+
+        let frame = try JSONDecoder().decode(GatewayFrame.self, from: Data(json.utf8))
+
+        #expect({
+            if case .unknown = frame { true } else { false }
+        }(), "expected .unknown frame")
+
+        guard case let .unknown(type, raw) = frame else {
+            return
+        }
+
+        #expect(type == "made-up")
+        #expect(raw["type"]?.value as? String == "made-up")
+        #expect(raw["foo"]?.value as? String == "bar")
+        #expect(raw["count"]?.value as? Int == 1)
+        let nested = raw["nested"]?.value as? [String: AnyCodable]
+        #expect(nested?["ok"]?.value as? Bool == true)
+    }
 }