diff --git a/app/src/__tests__/e2e/functional/custom-rules-paste-target.spec.ts b/app/src/__tests__/e2e/functional/custom-rules-paste-target.spec.ts
new file mode 100644
index 00000000..f8deedc9
--- /dev/null
+++ b/app/src/__tests__/e2e/functional/custom-rules-paste-target.spec.ts
@@ -0,0 +1,77 @@
+import { test, expect } from '@playwright/test';
+import { registerMocks } from '../../mocks/registerMocks';
+
+// The browser only offers Copy/Paste in its context or long-press menu when the
+// pointer lands on the <input> itself. The empty add-rule box must therefore keep
+// its input stretched across the visible field rather than collapsing to the
+// width of the (empty) typed text behind the placeholder.
+test.describe('@functional custom rules add box exposes a pasteable input', () => {
+  test('the empty add-rule field is hit by the input, not its wrapper', async ({ page }) => {
+    await registerMocks(page, {
+      authenticated: true,
+      customProfiles: [{ id: 'prof1', profile_id: 'prof1', name: 'Default', settings: { custom_rules: [] } }],
+    });
+    await page.goto('/custom-rules');
+
+    const input = page.locator('input#react-select-rule-composer-denylist-input');
+    await expect(input).toBeAttached();
+
+    const control = page.locator('.rule-composer__control').first();
+    const placeholder = page.locator('.rule-composer__placeholder').first();
+    await expect(placeholder).toBeVisible();
+    // Centre the field so neither the sticky header nor the mobile bottom nav overlaps it.
+    await control.evaluate((el) => el.scrollIntoView({ block: 'center' }));
+
+    const box = await placeholder.boundingBox();
+    const controlBox = await control.boundingBox();
+    if (!box || !controlBox) throw new Error('add-rule field did not render');
+
+    // Right-click / long-press where the placeholder text is drawn.
+    const hit = await page.evaluate(
+      ([x, y]) => { const el = document.elementFromPoint(x, y); return el ? el.tagName + '.' + el.className : null; },
+      [box.x + box.width / 2, box.y + box.height / 2],
+    );
+    expect(hit).toMatch(/^INPUT\b/);
+
+    // And the input spans the free space of the field, not a few pixels.
+    const inputBox = await input.boundingBox();
+    if (!inputBox) throw new Error('input has no box');
+    expect(inputBox.width).toBeGreaterThan(controlBox.width * 0.5);
+  });
+
+  test('a real right-click on the empty field reaches the input (desktop)', async ({ page }) => {
+    test.skip(!/chromium-desktop/i.test(test.info().project.name), 'context menus are a desktop pointer path');
+
+    await registerMocks(page, {
+      authenticated: true,
+      customProfiles: [{ id: 'prof1', profile_id: 'prof1', name: 'Default', settings: { custom_rules: [] } }],
+    });
+    await page.goto('/custom-rules');
+
+    const control = page.locator('.rule-composer__control').first();
+    const placeholder = page.locator('.rule-composer__placeholder').first();
+    await expect(placeholder).toBeVisible();
+    await control.evaluate((el) => el.scrollIntoView({ block: 'center' }));
+
+    // Record what the contextmenu event lands on and whether anything cancels it.
+    await page.evaluate(() => {
+      const w = window as Window & { __ctx?: { tag: string; id: string; prevented: boolean } };
+      document.addEventListener(
+        'contextmenu',
+        (e) => {
+          const t = e.target as HTMLElement;
+          w.__ctx = { tag: t.tagName, id: t.id, prevented: e.defaultPrevented };
+        },
+        { capture: false },
+      );
+    });
+
+    const box = await placeholder.boundingBox();
+    if (!box) throw new Error('add-rule field did not render');
+    await page.mouse.click(box.x + box.width / 2, box.y + box.height / 2, { button: 'right' });
+
+    const ctx = await page.evaluate(() => (window as Window & { __ctx?: unknown }).__ctx);
+    expect(ctx).toEqual({ tag: 'INPUT', id: 'react-select-rule-composer-denylist-input', prevented: false });
+    await expect(page.locator('input#react-select-rule-composer-denylist-input')).toBeFocused();
+  });
+});
diff --git a/app/src/pages/custom_rules/RuleComposer.tsx b/app/src/pages/custom_rules/RuleComposer.tsx
index 0543863d..7f30e450 100644
--- a/app/src/pages/custom_rules/RuleComposer.tsx
+++ b/app/src/pages/custom_rules/RuleComposer.tsx
@@ -146,6 +146,11 @@ const selectStyles: StylesConfig<RuleOption, true, RuleOptionGroup> = {
         color: "var(--tailwind-colors-slate-100)",
         caretColor: "var(--tailwind-colors-rdns-400)",
         minWidth: "6rem",
+        // react-select sizes the inner <input> to the mirrored typed text (0 min-content),
+        // so an empty field leaves a 2px-wide input under the placeholder. Browsers only
+        // offer Copy/Paste in the context or long-press menu when the pointer lands on
+        // the <input> itself, so let it fill the wrapper instead.
+        gridTemplateColumns: "0 1fr",
     }),
 };