K17 (refused said): the asks record says when an ask ended

decided already names ask, outcome refused, words and at; the record gains at beside state refused and answer.
Generated code waits for K21.

Builds: design 47 G §570, §638

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

operator-and-conversation/seats/operator-channel/fixtures/states.json

@@ -45,5 +45,20 @@
       "opened": "2026-11-10T10:00:00Z",
       "state": "held-back"
     }
+  },
+  {
+    "name": "an ask the router refused at take-in, closed (design 47 G 570)",
+    "of": "state:asks/<asker>.<id>",
+    "given": {
+      "answer": "refused: its expiry passes the bound of its highest option level",
+      "asker": "nats",
+      "at": "2026-11-11T10:00:01Z",
+      "asker_told": true,
+      "expires": "2026-11-12T10:00:00Z",
+      "headline": "Recreate a bus entry",
+      "key": "nats.r-1",
+      "opened": "2026-11-11T10:00:00Z",
+      "state": "refused"
+    }
   }
 ]

operator-and-conversation/seats/operator-channel/seat.json

@@ -319,6 +319,10 @@
               "answer": {
                 "type": "string",
                 "description": "how it ended, in words"
+              },
+              "at": {
+                "type": "string",
+                "description": "when it ended, RFC 3339; present once it ended, a refused ask's refusal time (design 47 G 570, 638)"
               }
             },
             "required": [