fix(board): prevent transient no threads state (#1151)

* fix(board): prevent transient no threads state

* fix(board): scope raw thread fallback by sort

* fix(board): keep flash table loading during feed sync

src/lib/utils/__tests__/raw-board-thread-state.test.ts

@@ -0,0 +1,63 @@
+import { describe, expect, it } from 'vitest';
+import type { Comment, CommunitiesPages, Community } from '@bitsocial/bitsocial-react-hooks';
+import { getRawBoardThreadState } from '../raw-board-thread-state';
+
+const rootThread = (cid: string): Comment =>
+  ({
+    cid,
+    postCid: cid,
+  }) as Comment;
+
+describe('getRawBoardThreadState', () => {
+  it('keeps the preloaded fallback scoped to the requested sort type', () => {
+    const community = {
+      posts: {
+        pageCids: {
+          new: 'new-page-1',
+        },
+        pages: {
+          active: {
+            comments: [],
+          },
+          new: {
+            comments: [rootThread('new-thread')],
+            nextCid: 'new-page-2',
+          },
+        },
+      },
+    } as Community;
+
+    expect(
+      getRawBoardThreadState({
+        accountId: undefined,
+        communitiesPages: {} as CommunitiesPages,
+        community,
+        sortType: 'active',
+      }),
+    ).toMatchObject({
+      isFullyLoaded: true,
+      rootThreadCids: new Set<string>(),
+    });
+  });
+
+  it('treats an empty preloaded requested-sort page as a fully loaded empty board', () => {
+    const community = {
+      posts: {
+        pages: {
+          active: {
+            comments: [],
+          },
+        },
+      },
+    } as Community;
+
+    expect(
+      getRawBoardThreadState({
+        accountId: undefined,
+        communitiesPages: {} as CommunitiesPages,
+        community,
+        sortType: 'active',
+      }).isFullyLoaded,
+    ).toBe(true);
+  });
+});