docs: remove warning and add TODO

Signed-off-by: Rob Walworth <[email protected]>

Author: rwalworth

Sources/Hiero/Client/ChannelBalancer.swift

@@ -20,12 +20,20 @@ import SwiftProtobuf
 /// - Complexity of maintaining accurate per-channel metrics
 /// - Race conditions in concurrent request tracking
 ///
+/// ## Timeout Handling
+/// This balancer does not enforce per-request timeouts. Timeout protection is
+/// provided at the execution layer via `ExponentialBackoff.maxElapsedTime` and
+/// `Backoff.requestTimeout`, which prevent indefinite hangs during retries.
+///
+/// - TODO: Implement GRPC-level timeouts using `Backoff.grpcTimeout`.
+///   To add this functionality, update `Execute.applyGrpcHeader()` to accept
+///   a timeout parameter and configure `CallOptions.timeLimit`. This would provide
+///   finer-grained timeout control for individual GRPC calls.
+///
 /// ## Related Types
 /// - `NodeConnection` - Uses ChannelBalancer for node-level load balancing
 /// - `MirrorNetwork` - Uses ChannelBalancer for mirror node distribution
-///
-/// - Warning: If a request to a non-existent host never returns, the system may hang.
-///   Consider implementing timeout handling at a higher level.
+/// - `Backoff` - Contains grpcTimeout field for future GRPC-level timeout support
 internal final class ChannelBalancer: GRPCChannel {
     // MARK: - Properties
 
@@ -42,12 +50,16 @@ internal final class ChannelBalancer: GRPCChannel {
     /// - Parameters:
     ///   - eventLoop: The event loop for channel operations
     ///   - targetSecurityPairs: Array of connection targets paired with their security configurations
+    ///
+    /// - Precondition: GRPC channel pool creation must succeed. If it fails, this is a
+    ///   programming error and the application should crash rather than continue with invalid state.
     internal init(
         eventLoop: EventLoop,
         targetSecurityPairs: [(GRPC.ConnectionTarget, GRPCChannelPool.Configuration.TransportSecurity)]
     ) {
         self.eventLoop = eventLoop
         self.channels = targetSecurityPairs.map { (target, security) in
+            // Crash intentionally if channel creation fails - no recovery possible at initialization
             try! GRPCChannelPool.with(target: target, transportSecurity: security, eventLoopGroup: eventLoop)
         }
     }

Sources/Hiero/Client/Client.swift

@@ -334,7 +334,10 @@ public final class Client: Sendable {
     public static func fromConfig(_ config: String) throws -> Self {
         let configData: ClientConfig
         do {
-            configData = try JSONDecoder().decode(ClientConfig.self, from: config.data(using: .utf8)!)
+            guard let data = config.data(using: .utf8) else {
+                throw HError.basicParse("Invalid UTF-8 in configuration string")
+            }
+            configData = try JSONDecoder().decode(ClientConfig.self, from: data)
         } catch let error as DecodingError {
             throw HError.basicParse(String(describing: error))
         }

Sources/Hiero/Client/NodeHealth.swift

@@ -116,7 +116,7 @@ internal enum NodeHealth: Sendable {
 
         // Apply exponential backoff
         var backoff = self.backoff
-        let backoffInterval = backoff.next()!
+        let backoffInterval = backoff.next()!  // Safe: backoff has unlimited max elapses time (never returns nil)
         let healthyAt = now.adding(nanos: backoffInterval.nanoseconds)
 
         self = .unhealthy(