Add additional subprocess diagnostics for the audita interface

internal/adapters/audita/subprocess.go

@@ -189,11 +189,16 @@ func (r *SubprocessRunner) Run(ctx context.Context, req PolishRequest) (PolishRe
 		StderrLogPath: req.StderrLogPath,
 	})
 	if err != nil {
-		return r.failureResult(req, reqModules, runRes, credentialPresent, primaryConcurrencyViaEnv), fmt.Errorf(
-			"run audita process (binary=%q, stdout_log=%q, stderr_log=%q): %w",
+		wrappedMessage := fmt.Sprintf(
+			"run audita process (binary=%q, stdout_log=%q, stderr_log=%q)",
 			r.binary,
 			req.StdoutLogPath,
 			req.StderrLogPath,
+		)
+		wrappedMessage = addSubprocessStreamHint(wrappedMessage, err)
+		return r.failureResult(req, reqModules, runRes, credentialPresent, primaryConcurrencyViaEnv), fmt.Errorf(
+			"%s: %w",
+			wrappedMessage,
 			err,
 		)
 	}
@@ -328,6 +333,17 @@ func validateProcessedOutput(path string) error {
 	return nil
 }
 
+func addSubprocessStreamHint(message string, runErr error) string {
+	if runErr == nil {
+		return message
+	}
+	lower := strings.ToLower(runErr.Error())
+	if strings.Contains(lower, "bad file descriptor") || strings.Contains(lower, "exit code 120") {
+		return message + "; hint=audita child process may have started with invalid stderr/stdout descriptors"
+	}
+	return message
+}
+
 func validateJSONFile(path string) error {
 	data, err := os.ReadFile(path)
 	if err != nil {