 +    state = StdoutState.CollectDiagnostic;
    }
  }
- 
-@@ -199,7 +227,7 @@ class KernelCompiler {
- 
+
+@@ -200,7 +228,7 @@ class KernelCompiler {
+
        if (await fingerprinter.doesFingerprintMatch()) {
          printTrace('Skipping kernel compilation. Fingerprint match.');
 -        return CompilerOutput(outputFilePath, 0);
 +        return CompilerOutput(outputFilePath, 0, /* sources */ null);
        }
      }
- 
-@@ -449,10 +477,13 @@ class ResidentCompiler {
+
+@@ -453,10 +481,13 @@ class ResidentCompiler {
          ? _mapFilename(request.mainPath, packageUriMapper) + ' '
          : '';
      _server.stdin.writeln('recompile $mainUri$inputKey');

     }
     _compileRequestNeedsConfirmation = false;
   }
@@ -617,6 +650,7 @@ class ResidentCompiler {
     }
     _stdoutHandler.reset();
     _server.stdin.writeln('reject');

     }
     _server.stdin.writeln(inputKey);
+    printTrace('<- $inputKey');

     return _stdoutHandler.compilerOutput.future;
   }
@@ -546,6 +577,7 @@ class ResidentCompiler {
       .listen((String message) { printError(message); });

     _server.stdin.writeln('compile $scriptUri');
+    printTrace('<- compile $scriptUri');

     return _stdoutHandler.compilerOutput.future;
   }
@@ -598,6 +630,7 @@ class ResidentCompiler {
   void accept() {
     if (_compileRequestNeedsConfirmation) {
       _server.stdin.writeln('accept');
