Ensure patched assertions are added before being removed, to avoid glitching

examples/box-and-client.js

@@ -73,6 +73,17 @@ new Ground(() => {
       });
       return [Syndicate.Observe(BoxState(_$)), handler];
     });
+    Dataspace.currentFacet().addEndpoint(() => {
+      let handler = Skeleton.analyzeAssertion(BoxState(__));
+      handler.callback = Dataspace.wrap((evt, vs) => {
+        if (evt === Skeleton.EVENT_REMOVED) {
+          Dataspace.currentFacet().actor.scheduleScript(() => {
+            console.log('box gone');
+          });
+        }
+      });
+      return [Syndicate.Observe(BoxState(__)), handler];
+    });
   });
 }).start().addStopHandler(() => {
   console.timeEnd('box-and-client-' + N.toString());

src/dataspace.js

@@ -200,12 +200,20 @@ Dataspace.prototype.addActor = function (name, bootProc, initialAssertions) {
 };
 
 Dataspace.prototype.applyPatch = function (ac, delta) {
+  let removals = [];
   delta.forEach((count, a) => {
     if (a !== void 0) {
-      this.index.adjustAssertion(a, count);
+      if (count > 0) {
+        this.index.adjustAssertion(a, count);
+      } else {
+        removals.push([count, a]);
+      }
       ac.cleanupChanges.change(a, -count);
     }
   });
+  removals.forEach(([count, a]) => {
+    this.index.adjustAssertion(a, count);
+  });
 };
 
 Dataspace.prototype.subscribe = function (handler) {