The node-engine owns the composition it alone runs (H1, H2)

ADR 0593 §1 and §7: compose, its bus reader and runtime reader, takein,
validate, the overlay generator, the composer's run and mesh-compose, and
the judgement of a move leave mesh-sdk for the node-engine's internal
packages, so no other module composes and a change to them rebuilds only
the node-engine. The shapes others read (the composer's request and
verdict, the overlay's names, compositions and answers) stay in mesh-sdk.
The node's grant is now a golden file of what the grants part composes,
since the composer of the bus's user list leaves mesh-sdk too.

Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL

cmd/mesh-compose/testdata/mesh-catalog/modules/snapd/module.json.captured

@@ -0,0 +1,31 @@
+{
+  "module": "snapd",
+  "version": "1",
+  "tools": [
+    "snapd_status",
+    "snapd_list",
+    "snapd_info",
+    "snapd_updates",
+    "snapd_disk_usage",
+    "snapd_services",
+    "snapd_changes",
+    "snapd_install",
+    "snapd_remove",
+    "snapd_refresh"
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "tools",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/snapd-tools",
+        "binary": "snapd-tools",
+        "loads": [
+          "snapd-tools"
+        ]
+      }
+    ]
+  }
+}