diff --git a/frontend/src/routes/SearchFilterBar.svelte b/frontend/src/routes/SearchFilterBar.svelte
index f9441d41..9786bec6 100644
--- a/frontend/src/routes/SearchFilterBar.svelte
+++ b/frontend/src/routes/SearchFilterBar.svelte
@@ -14,6 +14,7 @@ let {
 	receiverId = $bindable(''),
 	tagNames = $bindable<{ name: string; id?: string; color?: string; parentId?: string }[]>([]),
 	tagQ = $bindable(''),
+	tagOperator = $bindable<'AND' | 'OR'>('AND'),
 	sort = $bindable('DATE'),
 	dir = $bindable('desc'),
 	showAdvanced = $bindable(false),
@@ -31,6 +32,7 @@ let {
 	receiverId?: string;
 	tagNames?: { name: string; id?: string; color?: string; parentId?: string }[];
 	tagQ?: string;
+	tagOperator?: 'AND' | 'OR';
 	sort?: string;
 	dir?: string;
 	showAdvanced?: boolean;
@@ -153,6 +155,26 @@ $effect(() => {
 						onSearch();
 					}}
 				/>
+				{#if tagNames.length >= 2}
+					<div data-testid="and-or-toggle" class="mt-2 flex items-center gap-1">
+						<button
+							type="button"
+							class="rounded px-2 py-0.5 text-xs font-bold tracking-widest uppercase transition-colors {tagOperator === 'AND' ? 'bg-primary text-primary-fg' : 'bg-muted text-ink-2 hover:bg-line'}"
+							onclick={() => {
+								tagOperator = 'AND';
+								onSearch();
+							}}>AND</button
+						>
+						<button
+							type="button"
+							class="rounded px-2 py-0.5 text-xs font-bold tracking-widest uppercase transition-colors {tagOperator === 'OR' ? 'bg-primary text-primary-fg' : 'bg-muted text-ink-2 hover:bg-line'}"
+							onclick={() => {
+								tagOperator = 'OR';
+								onSearch();
+							}}>OR</button
+						>
+					</div>
+				{/if}
 			</div>
 
 			<!-- Sender -->
diff --git a/frontend/src/routes/SearchFilterBar.svelte.spec.ts b/frontend/src/routes/SearchFilterBar.svelte.spec.ts
index c3f8a454..86075e09 100644
--- a/frontend/src/routes/SearchFilterBar.svelte.spec.ts
+++ b/frontend/src/routes/SearchFilterBar.svelte.spec.ts
@@ -1,8 +1,10 @@
-import { describe, expect, it, vi } from 'vitest';
-import { render } from 'vitest-browser-svelte';
+import { describe, expect, it, vi, afterEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
 import { page } from 'vitest/browser';
 import SearchFilterBar from './SearchFilterBar.svelte';
 
+afterEach(() => cleanup());
+
 const defaultProps = {
 	onSearch: vi.fn()
 };
@@ -41,6 +43,68 @@ describe('SearchFilterBar – loading spinner', () => {
 	});
 });
 
+describe('SearchFilterBar – AND/OR tag operator toggle', () => {
+	async function openAdvanced() {
+		const filterBtn = page.getByRole('button', { name: 'Filter', exact: true });
+		await filterBtn.click();
+	}
+
+	it('hides AND/OR toggle when fewer than 2 tags are selected', async () => {
+		vi.stubGlobal(
+			'fetch',
+			vi.fn().mockResolvedValue({ ok: true, json: vi.fn().mockResolvedValue([]) })
+		);
+		render(SearchFilterBar, {
+			...defaultProps,
+			sort: 'DATE',
+			dir: 'desc',
+			tagNames: [{ name: 'Tag1' }]
+		});
+		await openAdvanced();
+		await expect.element(page.getByRole('button', { name: 'AND' })).not.toBeInTheDocument();
+		vi.unstubAllGlobals();
+	});
+
+	it('shows AND/OR toggle when 2+ tags are selected', async () => {
+		vi.stubGlobal(
+			'fetch',
+			vi.fn().mockResolvedValue({ ok: true, json: vi.fn().mockResolvedValue([]) })
+		);
+		render(SearchFilterBar, {
+			...defaultProps,
+			sort: 'DATE',
+			dir: 'desc',
+			tagNames: [{ name: 'Tag1' }, { name: 'Tag2' }]
+		});
+		await openAdvanced();
+		const toggle = page.getByTestId('and-or-toggle');
+		await expect.element(toggle).toBeInTheDocument();
+		await expect.element(toggle.getByRole('button', { name: 'AND' })).toBeInTheDocument();
+		await expect.element(toggle.getByRole('button', { name: 'OR' })).toBeInTheDocument();
+		vi.unstubAllGlobals();
+	});
+
+	it('calls onSearch when operator is toggled', async () => {
+		vi.stubGlobal(
+			'fetch',
+			vi.fn().mockResolvedValue({ ok: true, json: vi.fn().mockResolvedValue([]) })
+		);
+		const onSearch = vi.fn();
+		render(SearchFilterBar, {
+			...defaultProps,
+			onSearch,
+			sort: 'DATE',
+			dir: 'desc',
+			tagNames: [{ name: 'Tag1' }, { name: 'Tag2' }]
+		});
+		await openAdvanced();
+		const toggle = page.getByTestId('and-or-toggle');
+		await toggle.getByRole('button', { name: 'OR' }).click();
+		await expect.poll(() => onSearch.mock.calls.length).toBeGreaterThan(0);
+		vi.unstubAllGlobals();
+	});
+});
+
 describe('SearchFilterBar – tagQ live filter', () => {
 	it('calls onSearch when tag text changes in TagInput', async () => {
 		vi.stubGlobal(