diff --git a/trustgraph-flow/trustgraph/gateway/dispatch/mux.py b/trustgraph-flow/trustgraph/gateway/dispatch/mux.py
index b9bb45bc..7d62f163 100644
--- a/trustgraph-flow/trustgraph/gateway/dispatch/mux.py
+++ b/trustgraph-flow/trustgraph/gateway/dispatch/mux.py
@@ -123,20 +123,33 @@ class Mux:
                 return
 
             # Workspace resolution.  Authenticated sockets override
-            # the client-supplied workspace with the resolved value
-            # from the identity; mismatch is an access-denied error.
+            # any client-supplied workspace — on both the envelope and
+            # the inner request payload — with the resolved value from
+            # the identity.  A mismatched value at either layer is an
+            # access-denied error.  Injecting into the inner request
+            # means clients don't have to repeat the workspace in
+            # every payload; the same convenience HTTP callers get
+            # via enforce_workspace.
             if self.identity is not None:
-                requested_ws = data.get("workspace", "")
-                if requested_ws and requested_ws != self.identity.workspace:
-                    await self.ws.send_json({
-                        "id": request_id,
-                        "error": {
-                            "message": "access denied",
-                            "type": "access-denied",
-                        },
-                        "complete": True,
-                    })
-                    return
+                for layer, blob in (
+                        ("envelope", data),
+                        ("inner", data.get("request")),
+                ):
+                    if not isinstance(blob, dict):
+                        continue
+                    req = blob.get("workspace", "")
+                    if req and req != self.identity.workspace:
+                        await self.ws.send_json({
+                            "id": request_id,
+                            "error": {
+                                "message": "access denied",
+                                "type": "access-denied",
+                            },
+                            "complete": True,
+                        })
+                        return
+                    blob["workspace"] = self.identity.workspace
+
                 workspace = self.identity.workspace
             else:
                 workspace = data.get("workspace", "default")