Qualify optimistic tree reparenting with authoritative cycle rejection

test/fixtures/tree/TreeData.qx

@@ -0,0 +1,11 @@
+interface TreeData id "tree:data" revision "tree:data@1" {
+  operation reparent id "tree:reparent" : optional<interface-ref<TreeData>> -> unit {
+    call id "tree:reparent:call" execution transaction targets [browser, server];
+  }
+  queryable relation parent id "tree:parent" : optional-one interface TreeData {
+    resolve id "tree:parent:resolve" execution snapshot targets [browser, server];
+  }
+  queryable relation children id "tree:children" : many interface TreeData {
+    resolve id "tree:children:resolve" execution snapshot targets [browser, server];
+  }
+}

test/fixtures/tree/TreeRuntime.qx

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+external atom Node id "tree:node";
+import interface TreeData;
+package TreeRuntime id "tree:runtime" revision "tree:runtime@1" {
+  operation reparent id "tree:runtime:reparent" : optional<interface-ref<TreeData>> -> unit
+  mode call execution transaction targets [browser, server] receiver atom Node requires {
+    edge parent id "tree:move:parent" : optional-one interface TreeData [resolve, connect, disconnect];
+  } accept using check;
+  operation check id "tree:runtime:check" : optional<interface-ref<TreeData>> -> unit
+  mode call execution snapshot targets [server] receiver atom Node requires {
+    edge current id "tree:check:current" : optional-one interface TreeData [resolve];
+    interface ancestors id "tree:check:ancestors" : TreeData using [parent.resolve] from input;
+  };
+}

test/fixtures/tree/workspace.qx

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+workspace Tree id "workspace:tree" revision "workspace:tree@1" commit "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" {
+  import interface TreeData;
+  import package TreeRuntime;
+  atom Node id "tree:node";
+  conform Node as TreeData id "tree:node:data" {
+    private edge Parent id "tree:parent-edge" {
+      atom Node projection parent id "tree:parent-projection" optional-one;
+      interface TreeData projection children id "tree:children-projection" many;
+    }
+    bind parent.resolve to edge Parent.parent.resolve;
+    bind children.resolve to edge Parent.children.resolve;
+    bind reparent.call to package TreeRuntime.reparent with {
+      parent to edge Parent.parent;
+    } accept with {
+      current to edge Parent.parent;
+      ancestors to interface TreeData from input;
+    };
+  }
+}