diff --git a/pkg/executor/executor.go b/pkg/executor/executor.go
index c43ea0a6..3c3967bb 100644
--- a/pkg/executor/executor.go
+++ b/pkg/executor/executor.go
@@ -32,6 +32,16 @@ func Run(cmd *exec.Cmd) error {
 	return cmd.Run()
 }
 
+// StderrError is returned by RunAndLogLines when a command fails and produces
+// output on stderr. Callers can use errors.As to access the raw stderr content.
+type StderrError struct {
+	Message string
+}
+
+func (e *StderrError) Error() string {
+	return e.Message
+}
+
 type Executor struct {
 	cmd              *exec.Cmd
 	logProxyHookJSON bool
@@ -147,7 +157,7 @@ func (e *Executor) RunAndLogLines(ctx context.Context, logLabels map[string]stri
 	err := e.cmd.Run()
 	if err != nil {
 		if len(stdErr.Bytes()) > 0 {
-			return nil, fmt.Errorf("stderr: %s", stdErr.String())
+			return nil, &StderrError{Message: stdErr.String()}
 		}
 
 		return nil, fmt.Errorf("cmd run: %w", err)