clamped the effectiveTimeout and fixed the comment (#821)

So the problem is that the performRpc is a public function, and we never
sanity check if users provide values larger than the connection_timeout,
which might cause unexpected behavior.

This PR fixes the comment and also clamp the connection response timeout
if needed.

See similar PR on JS SDK:
livekit/client-sdk-js#1694

Author: xianshijing-lk

.changes/clamp-response-timeout

@@ -0,0 +1 @@
+patch type="fixed" "clamp response timeout in performRpc to minimal 1s"

Sources/LiveKit/Participant/LocalParticipant+RPC.swift

@@ -24,7 +24,10 @@ public extension LocalParticipant {
     ///   - destinationIdentity: The identity of the destination participant
     ///   - method: The method name to call
     ///   - payload: The payload to pass to the method
-    ///   - responseTimeout: Timeout for receiving a response after initial connection. (default 10s)
+    ///   - responseTimeout: Timeout for receiving a response after the initial connection (in seconds).
+    ///     If a value less than 8s is provided, it will be automatically clamped to 8s
+    ///     to ensure sufficient time for round-trip latency buffering.
+    ///     Default: 15s.
     /// - Returns: The response payload
     /// - Throws: RpcError on failure. Details in RpcError.message
     func performRpc(destinationIdentity: Identity,
@@ -40,8 +43,8 @@ public extension LocalParticipant {
 
         let requestId = UUID().uuidString
         let maxRoundTripLatency: TimeInterval = 7
-        let effectiveTimeout = responseTimeout - maxRoundTripLatency
-
+        let minEffectiveTimeout: TimeInterval = 1
+        let effectiveTimeout = max(responseTimeout - maxRoundTripLatency, minEffectiveTimeout)
         try await publishRpcRequest(destinationIdentity: destinationIdentity,
                                     requestId: requestId,
                                     method: method,

Tests/LiveKitTestSupport/Room.swift

@@ -210,7 +210,7 @@ public extension Room {
 
 public final class RoomWatcher<T: Decodable & Sendable>: RoomDelegate, Sendable {
     public let id: String
-    public let didReceiveDataCompleters = CompleterMapActor<T>(label: "Data receive completer", defaultTimeout: 10)
+    public let didReceiveDataCompleters = CompleterMapActor<T>(label: "Data receive completer", defaultTimeout: 15)
 
     // MARK: - Private