Handle synchronous comment snapshots in video modal

js/ui/videoModalCommentController.js

@@ -202,21 +202,29 @@ export default class VideoModalCommentController {
     this.videoModal.resetCommentComposer?.();
     this.videoModal.setCommentStatus?.("Loading comments…");
 
-    const loadPromise = this.commentThreadService.loadThread({
+    const loadResult = this.commentThreadService.loadThread({
       video,
       parentCommentId: null,
       limit: this.modalCommentLimit,
     });
 
-    if (!loadPromise || typeof loadPromise.then !== "function") {
+    if (!loadResult) {
       this.applyCommentComposerAuthState();
       return;
     }
 
-    this.modalCommentLoadPromise = loadPromise;
-    loadPromise
+    if (typeof loadResult.then !== "function") {
+      const didRenderSnapshot = this.handleCommentThreadReady(loadResult);
+      if (didRenderSnapshot === false) {
+        this.applyCommentComposerAuthState();
+      }
+      return;
+    }
+
+    this.modalCommentLoadPromise = loadResult;
+    loadResult
       .then((snapshot) => {
-        if (this.modalCommentLoadPromise === loadPromise) {
+        if (this.modalCommentLoadPromise === loadResult) {
           this.modalCommentLoadPromise = null;
         }
 
@@ -226,7 +234,7 @@ export default class VideoModalCommentController {
         }
       })
       .catch((error) => {
-        if (this.modalCommentLoadPromise === loadPromise) {
+        if (this.modalCommentLoadPromise === loadResult) {
           this.modalCommentLoadPromise = null;
         }
         this.handleCommentThreadError(error);

tests/video-modal-comments.test.mjs

@@ -240,6 +240,60 @@ test(
   },
 );
 
+test(
+  "Controller renders synchronous loadThread snapshots immediately",
+  async (t) => {
+    const { modal, cleanup } = await setupModal();
+    t.after(cleanup);
+
+    const snapshot = {
+      videoEventId: "video-sync-snapshot",
+      parentCommentId: null,
+      commentsById: new Map([
+        [
+          "sync-comment",
+          createCommentEvent({
+            id: "sync-comment",
+            pubkey: "pk-sync",
+            content: "Snapshot delivered instantly",
+            createdAt: 1700000200,
+          }),
+        ],
+      ]),
+      childrenByParent: new Map([[null, ["sync-comment"]]]),
+      profiles: new Map([["pk-sync", { name: "Synchronous" }]]),
+    };
+
+    const controller = new VideoModalCommentController({
+      commentThreadService: {
+        defaultLimit: 1,
+        setCallbacks: () => {},
+        teardown: () => {},
+        loadThread: () => snapshot,
+      },
+      videoModal: modal,
+      auth: {
+        isLoggedIn: () => false,
+      },
+    });
+
+    controller.load({ id: "video-sync-snapshot", enableComments: true });
+    await Promise.resolve();
+
+    const renderedComments = Array.from(
+      modal.commentsList.querySelectorAll("[data-comment-id]") || [],
+    );
+    assert.equal(renderedComments.length, 1);
+    assert.equal(renderedComments[0].dataset.commentId, "sync-comment");
+
+    const statusText =
+      modal.commentsStatusMessage?.textContent.trim().replace(/\s+/g, " ") ||
+      "";
+    assert.equal(statusText, "");
+    assert.equal(modal.commentComposerState.reason, "login-required");
+  },
+);
+
 test(
   "VideoModalCommentController attaches profiles using normalized pubkeys",
   async () => {