Fix header reveal flash on note switch

Author: ChristianChiarulli

app/src/features/editor/extensions/markdown-decorations/markdown-decorations.test.ts

@@ -40,6 +40,11 @@ function createDecoratedView(doc: string, selection: EditorSelection) {
   });
 }
 
+async function flush() {
+  await new Promise((resolve) => setTimeout(resolve, 0));
+  await new Promise(requestAnimationFrame);
+}
+
 afterEach(() => {
   document.body.replaceChildren();
 });
@@ -189,4 +194,30 @@ describe("markdownDecorations pointer selection normalization", () => {
     expect(view.state.selection.main.head).toBe(2);
     view.destroy();
   });
+
+  it("keeps heading syntax hidden when a new note loads into an inactive editor", async () => {
+    const view = createDecoratedView(
+      "# Old heading\nBody",
+      EditorSelection.create([EditorSelection.cursor(2)]),
+    );
+
+    view.contentDOM.focus();
+    await flush();
+
+    view.dom.classList.add("comet-editor-inactive");
+    view.dispatch({
+      changes: {
+        from: 0,
+        to: view.state.doc.length,
+        insert: "# New heading\nBody",
+      },
+    });
+
+    await flush();
+
+    const firstLine = view.dom.querySelector(".cm-line");
+    expect(firstLine?.textContent).toBe("New heading");
+
+    view.destroy();
+  });
 });

app/src/features/editor/extensions/markdown-decorations/plugin.ts

@@ -129,12 +129,16 @@ function expandedVisibleRanges(
   return ranges;
 }
 
+function hasActiveEditorFocus(view: EditorView) {
+  return view.hasFocus && !view.dom.classList.contains("comet-editor-inactive");
+}
+
 function buildDecorations(
   view: EditorView,
   searchMatches: SearchMatch[],
 ): { atomicRanges: DecorationSet; decorations: DecorationSet } {
   const { state } = view;
-  const hasFocus = view.hasFocus;
+  const hasFocus = hasActiveEditorFocus(view);
   const debugEnabled = isEditorDebugEnabled();
   const ranges = expandedVisibleRanges(view);
   const ctx: BuilderContext = {