diff --git a/.agents/skills/multi-agent-mux-delegate-job/scripts/mqtt_common.py b/.agents/skills/multi-agent-mux-delegate-job/scripts/mqtt_common.py
index 0b8a480..ac442be 100644
--- a/.agents/skills/multi-agent-mux-delegate-job/scripts/mqtt_common.py
+++ b/.agents/skills/multi-agent-mux-delegate-job/scripts/mqtt_common.py
@@ -33,37 +33,81 @@ import paho.mqtt.client as mqtt
 
 logger = logging.getLogger("delegate_job.mqtt_common")
 
-def _load_dotenv(workspace_dir: str = None) -> None:
-    """Load .env file from workspace if it exists and env var not already set.
+_warned_deprecated_env = False
+_warned_coexistence_env = False
+
+def _load_dotenv(workspace_dir: Optional[str] = None) -> None:
+    """Load .mam.env (or .env fallback) from workspace if it exists.
     
-    This ensures Python scripts get the same env vars as the shell wrapper
-    scripts that source .env. Only sets vars that are not already in os.environ
-    (i.e. OS env takes precedence over .env file).
+    Only sets vars that are not already in os.environ
+    (i.e. OS env takes precedence over env files).
     """
-    import os
+    global _warned_deprecated_env, _warned_coexistence_env
+    
+    # 1. Check explicit MAM_ENV_FILE override
+    explicit_file = os.environ.get("MAM_ENV_FILE")
+    if explicit_file:
+        if os.path.isfile(explicit_file):
+            _parse_env_file(explicit_file)
+        return
+
+    # 2. Resolve workspace directory with boundary marker check (.agents or .git)
     if workspace_dir is None:
-        # Walk up from this script to find workspace root
-        d = os.path.dirname(os.path.abspath(__file__))
-        for _ in range(5):
-            if os.path.isfile(os.path.join(d, ".env")):
+        curr = os.path.dirname(os.path.abspath(__file__))
+        resolved_root = None
+        while curr and curr != os.path.dirname(curr):
+            if os.path.isdir(os.path.join(curr, ".agents")) or os.path.exists(os.path.join(curr, ".git")):
+                resolved_root = curr
                 break
-            d = os.path.dirname(d)
+            curr = os.path.dirname(curr)
+        if not resolved_root:
+            return
+        d = resolved_root
     else:
         d = workspace_dir
-    env_path = os.path.join(d, ".env")
-    if not os.path.isfile(env_path):
-        return
-    with open(env_path, "r") as f:
-        for line in f:
-            line = line.strip()
-            if not line or line.startswith("#"):
-                continue
-            if "=" in line:
-                key, _, val = line.partition("=")
-                key = key.strip()
-                val = val.strip().strip('"').strip("'")
-                if key and key not in os.environ:
-                    os.environ[key] = val
+
+    mam_env_path = os.path.join(d, ".mam.env")
+    legacy_env_path = os.path.join(d, ".env")
+
+    has_mam = os.path.isfile(mam_env_path)
+    has_legacy = os.path.isfile(legacy_env_path)
+
+    if has_mam and has_legacy:
+        if not _warned_coexistence_env:
+            logger.warning(
+                "Both '%s' and '%s' exist. Loading '%s'. "
+                "Consider removing or migrating '%s'.",
+                mam_env_path, legacy_env_path, mam_env_path, legacy_env_path
+            )
+            _warned_coexistence_env = True
+        _parse_env_file(mam_env_path)
+    elif has_mam:
+        _parse_env_file(mam_env_path)
+    elif has_legacy:
+        if not _warned_deprecated_env:
+            logger.warning(
+                "Loading deprecated config file '%s'. "
+                "Please migrate to '.mam.env'.",
+                legacy_env_path
+            )
+            _warned_deprecated_env = True
+        _parse_env_file(legacy_env_path)
+
+def _parse_env_file(path: str) -> None:
+    try:
+        with open(path, "r", encoding="utf-8") as f:
+            for line in f:
+                line = line.strip()
+                if not line or line.startswith("#"):
+                    continue
+                if "=" in line:
+                    key, _, val = line.partition("=")
+                    key = key.strip()
+                    val = val.strip().strip('"').strip("'")
+                    if key and key not in os.environ:
+                        os.environ[key] = val
+    except Exception as e:
+        logger.warning("Failed to parse env file %s: %s", path, e)
 
 _load_dotenv()