diff --git a/nix/templates/harness-base.nix b/nix/templates/harness-base.nix
index d7d64330..39ac5684 100644
--- a/nix/templates/harness-base.nix
+++ b/nix/templates/harness-base.nix
@@ -60,8 +60,8 @@ let
     CLAUDE_CODE_RESUME_INTERRUPTED_TURN = "1";
     # Use the simpler system prompt variant suited to headless operation.
     CLAUDE_CODE_SIMPLE_SYSTEM_PROMPT = "1";
-    # Tag remote-control sessions with "<hive>/<agent>" for identification.
-    CLAUDE_REMOTE_CONTROL_SESSION_NAME_PREFIX = "${hiveDisplayName}/${userName}";
+    # Tag remote-control sessions with "<hive>-<agent>" for identification.
+    CLAUDE_REMOTE_CONTROL_SESSION_NAME_PREFIX = "${hiveDisplayName}-${userName}";
   };
   otelSettingsEnv = {
     CLAUDE_CODE_ENABLE_TELEMETRY = "1";