diff --git a/frontend/src/routes/documents/+page.svelte b/frontend/src/routes/documents/+page.svelte
index 22f756d3..80159e25 100644
--- a/frontend/src/routes/documents/+page.svelte
+++ b/frontend/src/routes/documents/+page.svelte
@@ -36,46 +36,84 @@ let showAdvanced = $state(untrack(hasAdvancedFilters));
 
 let searchTimer: ReturnType<typeof setTimeout>;
 
+type FilterSnapshot = {
+	q: string;
+	from: string;
+	to: string;
+	senderId: string;
+	receiverId: string;
+	tags: string[];
+	sort: string;
+	dir: string;
+	tagQ: string;
+	tagOp: 'AND' | 'OR';
+};
+
+/**
+ * Builds a URLSearchParams from a filter snapshot. Single source of truth for
+ * which params the `/documents` URL understands — add a filter here and both
+ * filter-change nav (triggerSearch) and page nav (buildPageHref) will pick it
+ * up. `page` is appended only when > 0 so the default page 0 stays out of the
+ * URL, keeping the filter-change-resets-to-page-0 behaviour implicit.
+ */
+function buildSearchParams(filters: FilterSnapshot, targetPage?: number): SvelteURLSearchParams {
+	const params = new SvelteURLSearchParams();
+	if (filters.q) params.set('q', filters.q);
+	if (filters.from) params.set('from', filters.from);
+	if (filters.to) params.set('to', filters.to);
+	if (filters.senderId) params.set('senderId', filters.senderId);
+	if (filters.receiverId) params.set('receiverId', filters.receiverId);
+	filters.tags.forEach((tag) => params.append('tag', tag));
+	if (filters.sort) params.set('sort', filters.sort);
+	if (filters.dir) params.set('dir', filters.dir);
+	if (filters.tagQ) params.set('tagQ', filters.tagQ);
+	if (filters.tagOp === 'OR') params.set('tagOp', 'OR');
+	if (targetPage !== undefined && targetPage > 0) params.set('page', String(targetPage));
+	return params;
+}
+
 /**
  * Rebuilds the URL from the CURRENT local filter state. `page` is intentionally
- * not carried over — any filter change implicitly resets back to page 0, which
- * is the expected behaviour. For page-only navigation use {@link buildPageHref}
- * instead, which preserves every filter from the server `data`.
+ * not carried over — any filter change implicitly resets back to page 0.
  */
 function triggerSearch() {
-	const params = new SvelteURLSearchParams();
-	if (q) params.set('q', q);
-	if (from) params.set('from', from);
-	if (to) params.set('to', to);
-	if (senderId) params.set('senderId', senderId);
-	if (receiverId) params.set('receiverId', receiverId);
-	tagNames.forEach((tag) => params.append('tag', tag.name));
-	if (sort) params.set('sort', sort);
-	if (dir) params.set('dir', dir);
-	if (tagQ) params.set('tagQ', tagQ);
-	if (tagOperator === 'OR') params.set('tagOp', 'OR');
+	const params = buildSearchParams({
+		q,
+		from,
+		to,
+		senderId,
+		receiverId,
+		tags: tagNames.map((t) => t.name),
+		sort,
+		dir,
+		tagQ,
+		tagOp: tagOperator
+	});
 	goto(`/documents?${params.toString()}`, { keepFocus: true, noScroll: true });
 }
 
 /**
- * Builds the href for a Pagination prev/next link. Preserves every current
- * filter param and only updates `page`. Uses a normal <a href> (not goto)
- * so SvelteKit's default scroll restoration brings the user to the top of
- * the new slice — the expected behaviour for page navigation.
+ * Builds the href for a Pagination prev/next link. Preserves every filter
+ * param from server `data` and updates `page`. Uses a normal <a href> (not
+ * goto) so SvelteKit's default scroll restoration brings the user to the top
+ * of the new slice — the expected behaviour for page navigation.
  */
 function buildPageHref(targetPage: number): string {
-	const params = new SvelteURLSearchParams();
-	if (data.q) params.set('q', data.q);
-	if (data.from) params.set('from', data.from);
-	if (data.to) params.set('to', data.to);
-	if (data.senderId) params.set('senderId', data.senderId);
-	if (data.receiverId) params.set('receiverId', data.receiverId);
-	(data.tags || []).forEach((t: string) => params.append('tag', t));
-	if (data.sort) params.set('sort', data.sort);
-	if (data.dir) params.set('dir', data.dir);
-	if (data.tagQ) params.set('tagQ', data.tagQ);
-	if (data.tagOp === 'OR') params.set('tagOp', 'OR');
-	if (targetPage > 0) params.set('page', String(targetPage));
+	const params = buildSearchParams(
+		{
+			q: data.q || '',
+			from: data.from || '',
+			to: data.to || '',
+			senderId: data.senderId || '',
+			receiverId: data.receiverId || '',
+			tags: data.tags || [],
+			sort: data.sort || '',
+			dir: data.dir || '',
+			tagQ: data.tagQ || '',
+			tagOp: (data.tagOp as 'AND' | 'OR') || 'AND'
+		},
+		targetPage
+	);
 	const qs = params.toString();
 	return qs ? `/documents?${qs}` : '/documents';
 }