feat: 2025-11-25 review fixes (#201)

* fix: review fixes of the latest changes

* fix: updated unit tests

* chore: more conformance compliance improvements

* chore: reverted protocol changes

* chore: more compliance improvements

* chore: more conformance compliance improvements

* chore: improvements to the backcompat and updated to Tool unit tests

* chore: ci update

Sources/MCP/Base/PendingRequest.swift

@@ -0,0 +1,43 @@
+import class Foundation.JSONDecoder
+import class Foundation.JSONEncoder
+
+/// An error indicating a type mismatch when decoding a pending request response.
+struct TypeMismatchError: Swift.Error {}
+
+/// A pending request with a continuation for the result.
+struct PendingRequest<T> {
+    let continuation: CheckedContinuation<T, Swift.Error>
+}
+
+/// A type-erased pending request.
+struct AnyPendingRequest: Sendable {
+    private let _resume: @Sendable (Result<Any, Swift.Error>) -> Void
+
+    init<T: Sendable & Decodable>(_ request: PendingRequest<T>) {
+        _resume = { result in
+            switch result {
+            case .success(let value):
+                if let typedValue = value as? T {
+                    request.continuation.resume(returning: typedValue)
+                } else if let value = value as? Value,
+                    let data = try? JSONEncoder().encode(value),
+                    let decoded = try? JSONDecoder().decode(T.self, from: data)
+                {
+                    request.continuation.resume(returning: decoded)
+                } else {
+                    request.continuation.resume(throwing: TypeMismatchError())
+                }
+            case .failure(let error):
+                request.continuation.resume(throwing: error)
+            }
+        }
+    }
+
+    func resume(returning value: Any) {
+        _resume(.success(value))
+    }
+
+    func resume(throwing error: Swift.Error) {
+        _resume(.failure(error))
+    }
+}