Run the router as its own account, ask unlinking of the linked account, and take no approval where an agent can become root (hq ADR 0259 §7, §8)

modules/messenger/module.json

@@ -2,6 +2,7 @@
   "module": "messenger",
   "version": "1",
   "slug": "msgr",
+  "runs-as": "messenger",
   "seats": [
     {
       "name": "operator-channel",
@@ -92,6 +93,10 @@
     },
     "identities"
   ],
+  "own-secrets": {
+    "broker": "${dir:state}/broker"
+  },
+  "secrets-owner": "messenger",
   "tools": [
     "messenger_status",
     "messenger_recent",
@@ -101,11 +106,19 @@
     "messenger_unlink"
   ],
   "resources": [
+    {
+      "id": "account",
+      "type": "user",
+      "name": "messenger",
+      "shell": "/usr/bin/nologin",
+      "home": "/var/lib/messenger"
+    },
     {
       "id": "state",
       "type": "directory",
       "mode": "0700",
-      "place": "."
+      "place": ".",
+      "owner": "messenger"
     },
     {
       "id": "settings",
@@ -113,7 +126,8 @@
       "path": "${dir:state}/settings.json",
       "mode": "0600",
       "merge": "json",
-      "content": "{\n  \"time-zone\": \"\"\n}\n"
+      "content": "{\n  \"time-zone\": \"\"\n}\n",
+      "owner": "messenger"
     }
   ],
   "build": {
@@ -129,7 +143,8 @@
           "messenger"
         ],
         "env": {
-          "MESH_MESSENGER_SETTINGS": "${dir:state}/settings.json"
+          "MESH_MESSENGER_SETTINGS": "${dir:state}/settings.json",
+          "MESH_MESSENGER_STATE": "${dir:state}"
         }
       }
     ]