minio: read who holds a seat from the placement seat's state, not the controller's seats (issue 1955, ADR 0571 clause 4)

modules/minio/cmd/object-store/server_test.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"encoding/json"
 	"errors"
 	"net/url"
 	"os"
@@ -25,12 +24,13 @@ const grantFile = `{
   ]
 }`
 
-// The seats answer is the controller's (mesh-controller.seats read on 2026-10-21): seats[].holders[] of {node, module},
-// and outside[] of {Claim, Node, Module}.
-const seatsAnswer = `{"answer": {"seats": [
-  {"seat": "node-files", "scope": "node", "holders": [{"node": "g14", "module": "mesh-files"}, {"node": "shanks", "module": "mesh-files"}]},
-  {"seat": "node-backup", "scope": "node", "holders": [{"node": "g14", "module": "restic"}]}
- ], "outside": [{"Claim": "printer", "Scope": "mesh", "Node": "shanks", "Module": "brother", "Site": "home", "Kind": ""}]}}`
+// The placement seat's state of who holds which seat (seat-holders): a key per node seat and node, a key per mesh seat.
+var seatHolderKeys = map[string][]byte{
+	"node-files.g14":    []byte(`{"v":1,"seat":"node-files","scope":"node","node":"g14","holders":[{"module":"mesh-files","node":"g14"}]}`),
+	"node-files.shanks": []byte(`{"v":1,"seat":"node-files","scope":"node","node":"shanks","holders":[{"module":"mesh-files","node":"shanks"}]}`),
+	"node-backup.g14":   []byte(`{"v":1,"seat":"node-backup","scope":"node","node":"g14","holders":[{"module":"restic","node":"g14"}]}`),
+	"printer":           []byte(`{"v":1,"seat":"printer","scope":"mesh","holders":[{"module":"brother","node":"shanks"}]}`),
+}
 
 type rig struct {
 	s          *server
@@ -64,12 +64,12 @@ func newRig(t *testing.T) *rig {
 		t.Fatal(err)
 	}
 	s.now = func() time.Time { return r.now }
-	s.seats = func() (json.RawMessage, error) {
+	s.seats = func() (map[string][]byte, error) {
 		r.seatsCalls++
 		if r.seatsErr != nil {
 			return nil, r.seatsErr
 		}
-		return json.RawMessage(seatsAnswer), nil
+		return seatHolderKeys, nil
 	}
 	r.s = s
 	return r