fix(b3): eliminate command -v herdr bash function false positive in preflight checks (100% PASS)

.agents/skills/multi-agent-mux-create/SKILL.md

@@ -34,7 +34,10 @@ Before doing anything, verify the environment:
 
 ```bash
 # 1) herdr available and isolated server status
-command -v herdr || { echo "ERROR: herdr not installed"; exit 1; }
+# Use lib.sh's has_real_herdr, NOT `command -v herdr` / `type -P herdr`: once
+# lib.sh is sourced the former matches its herdr() function and the latter
+# matches the .mam/shim wrapper, so both pass on a host with no herdr (B-3).
+has_real_herdr || { echo "ERROR: herdr not installed"; exit 1; }
 echo "Herdr session name: ${HERDR_SESSION_NAME:-default}"
 
 # 2) claude / agy available