         process: ProcessHandle,
         result: CommandExtendedResult
     ) {
+        if let buffer = self.nonSwiftMessageBuffers[command.name] {
+            queue.async {
+                self.progressAnimation.clear()
+                self.outputStream <<< buffer
+                self.outputStream.flush()
+                self.nonSwiftMessageBuffers[command.name] = nil
+            }
+        }
         if result.result == .failed {
             // The command failed, so we queue up an asynchronous task to see if we have any error messages from the target to provide advice about.
             queue.async {

    /// Swift parsers keyed by llbuild command name.
    private var swiftParsers: [String: SwiftCompilerOutputParser] = [:]

    /// The build execution context.
    private let buildExecutionContext: BuildExecutionContext


            swiftParser.parse(bytes: data)
        } else {
            queue.async {
                self.nonSwiftMessageBuffers[command.name, default: []] += data
            }
        }
    }
