fix(feeds): force infinite scroll on multiboards and canonicalize page URLs

src/lib/utils/__tests__/route-utils.test.ts

@@ -0,0 +1,29 @@
+import { describe, it, expect } from 'vitest';
+import { normalizeMultiboardFeedPath } from '../route-utils';
+
+describe('normalizeMultiboardFeedPath', () => {
+  it('normalizes /all/3 -> /all', () => {
+    expect(normalizeMultiboardFeedPath('/all/3')).toBe('/all');
+  });
+
+  it('normalizes /all/1w/3 -> /all/1w', () => {
+    expect(normalizeMultiboardFeedPath('/all/1w/3')).toBe('/all/1w');
+  });
+
+  it('normalizes /subs/2/settings -> /subs/settings', () => {
+    expect(normalizeMultiboardFeedPath('/subs/2/settings')).toBe('/subs/settings');
+  });
+
+  it('normalizes /mod/catalog/4 -> /mod/catalog', () => {
+    expect(normalizeMultiboardFeedPath('/mod/catalog/4')).toBe('/mod/catalog');
+  });
+
+  it('leaves non-multiboard paths unchanged', () => {
+    expect(normalizeMultiboardFeedPath('/biz')).toBe('/biz');
+    expect(normalizeMultiboardFeedPath('/biz/3')).toBe('/biz/3');
+    expect(normalizeMultiboardFeedPath('/biz/1w/2')).toBe('/biz/1w/2');
+    expect(normalizeMultiboardFeedPath('/biz/catalog/4')).toBe('/biz/catalog/4');
+    expect(normalizeMultiboardFeedPath('/pending/0')).toBe('/pending/0');
+    expect(normalizeMultiboardFeedPath('/')).toBe('/');
+  });
+});

src/lib/utils/route-utils.ts

@@ -150,6 +150,43 @@ export const BOARD_PAGE_REGEX = /^([1-9]|10)$/;
 
 export const isBoardFeedPageNumber = (segment: string): boolean => BOARD_PAGE_REGEX.test(segment);
 
+/** Internal: check if segment is a multiboard root (all, subs, mod) */
+function isMultiboardRoot(segment: string): boolean {
+  return segment === 'all' || segment === 'subs' || segment === 'mod';
+}
+
+/** Internal: check if pathname is a multiboard feed path (starts with /all, /subs, or /mod) */
+function isMultiboardFeedPath(pathname: string): boolean {
+  const trimmed = pathname.replace(/\/$/, '');
+  const segments = trimmed.split('/').filter(Boolean);
+  return segments.length > 0 && isMultiboardRoot(segments[0]);
+}
+
+/**
+ * Normalize multiboard feed paths by removing trailing page-number segments (1–10),
+ * while preserving /settings and valid time-filter segments.
+ * Non-multiboard paths are returned unchanged.
+ */
+export const normalizeMultiboardFeedPath = (pathname: string): string => {
+  let path = pathname.replace(/\/$/, '');
+  if (!isMultiboardFeedPath(path)) {
+    return pathname;
+  }
+
+  const hasSettings = path.endsWith('/settings');
+  if (hasSettings) {
+    path = path.replace(/\/settings$/, '');
+  }
+
+  const segments = path.split('/').filter(Boolean);
+  if (segments.length > 1 && isBoardFeedPageNumber(segments[segments.length - 1])) {
+    const newPath = '/' + segments.slice(0, -1).join('/');
+    return hasSettings ? newPath + '/settings' : newPath;
+  }
+
+  return hasSettings ? path + '/settings' : path;
+};
+
 /** Strip trailing page number (1–10) from path for feed cache key */
 export const stripPageFromFeedPath = (path: string): string => {
   const segments = path.split('/').filter(Boolean);