K6 (one capabilities event): the node-engine seat says manifest-reads-changed alone

capabilities-changed and its body go, the one event of a node's stated capabilities is manifest-reads-changed, which
already carries why. Generated code waits for K21.

Builds: design 47 G §590

Claude-Session: https://claude.ai/code/session_01JG73KEq4zoDfM9WtYpcQgZ

seats/node-engine/fixtures/events.json

@@ -131,19 +131,5 @@
       "stopped": true,
       "at": "2026-11-11T09:00:00Z"
     }
-  },
-  {
-    "name": "capabilities-changed is said",
-    "of": "event:capabilities-changed",
-    "subject": "mesh.seat.node-engine.event.capabilities-changed.ace",
-    "given": {
-      "v": 1,
-      "node": "ace",
-      "capabilities": [
-        "build-go",
-        "docker"
-      ],
-      "at": "2026-11-09T20:02:00Z"
-    }
   }
 ]

seats/node-engine/seat.json

@@ -904,13 +904,6 @@
       "body": {
         "$ref": "#/defs/Running"
       }
-    },
-    {
-      "name": "capabilities-changed",
-      "subject": "capabilities-changed.<node>",
-      "body": {
-        "$ref": "#/defs/CapabilitiesChanged"
-      }
     }
   ],
   "family": {
@@ -2929,38 +2922,6 @@
         "at"
       ]
     },
-    "CapabilitiesChanged": {
-      "type": "object",
-      "description": "a node's capabilities changed, which the assigner places by",
-      "properties": {
-        "v": {
-          "type": "integer",
-          "description": "the layout's version"
-        },
-        "node": {
-          "type": "string",
-          "description": "the node"
-        },
-        "capabilities": {
-          "type": "array",
-          "items": {
-            "type": "string"
-          },
-          "description": "its capabilities now"
-        },
-        "at": {
-          "type": "string",
-          "description": "when, RFC 3339",
-          "format": "date-time"
-        }
-      },
-      "required": [
-        "v",
-        "node",
-        "capabilities",
-        "at"
-      ]
-    },
     "ProcessBuild": {
       "type": "object",
       "description": "the build one process of a module was started with",