diff --git a/backend/Cargo.lock b/backend/Cargo.lock
index ec54b59..8ee1d71 100644
--- a/backend/Cargo.lock
+++ b/backend/Cargo.lock
@@ -1558,7 +1558,7 @@ checksum = "c41e0c4fef86961ac6d6f8a82609f55f31b05e4fce149ac5710e439df7619ba4"
 
 [[package]]
 name = "mangalord"
-version = "0.118.0"
+version = "0.118.1"
 dependencies = [
  "anyhow",
  "argon2",
diff --git a/backend/Cargo.toml b/backend/Cargo.toml
index a25f41a..b1a8515 100644
--- a/backend/Cargo.toml
+++ b/backend/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mangalord"
-version = "0.118.0"
+version = "0.118.1"
 edition = "2021"
 default-run = "mangalord"
 
diff --git a/frontend/e2e/detail-tag-add.spec.ts b/frontend/e2e/detail-tag-add.spec.ts
new file mode 100644
index 0000000..5292e01
--- /dev/null
+++ b/frontend/e2e/detail-tag-add.spec.ts
@@ -0,0 +1,88 @@
+import { test, expect, type Page } from './fixtures';
+
+// Adding a tag on the detail page should feel instant: the chip appears
+// optimistically while the request is in flight, and is reconciled with the
+// server's (normalized) tag on success.
+
+const mangaId = 'e1111111-1111-1111-1111-111111111111';
+
+async function mockDetail(page: Page) {
+    await page.route('**/api/v1/auth/config', (r) =>
+        r.fulfill({
+            status: 200,
+            contentType: 'application/json',
+            body: JSON.stringify({ self_register_enabled: true, private_mode: false })
+        })
+    );
+    await page.route('**/api/v1/auth/me', (r) =>
+        r.fulfill({
+            status: 200,
+            contentType: 'application/json',
+            body: JSON.stringify({ user: { id: 'u1', username: 'reader', created_at: '2026-01-01T00:00:00Z', is_admin: false } })
+        })
+    );
+    await page.route('**/api/v1/auth/me/preferences', (r) =>
+        r.fulfill({ status: 200, contentType: 'application/json', body: '{}' })
+    );
+    await page.route('**/api/v1/me/bookmarks*', (r) =>
+        r.fulfill({ status: 200, contentType: 'application/json', body: JSON.stringify({ items: [], page: { limit: 50, offset: 0, total: 0 } }) })
+    );
+    await page.route(`**/api/v1/mangas/${mangaId}/chapters*`, (r) =>
+        r.fulfill({ status: 200, contentType: 'application/json', body: JSON.stringify({ items: [], page: { limit: 50, offset: 0, total: 0 } }) })
+    );
+    await page.route(`**/api/v1/mangas/${mangaId}/similar`, (r) =>
+        r.fulfill({ status: 200, contentType: 'application/json', body: JSON.stringify({ items: [] }) })
+    );
+    await page.route(`**/api/v1/me/read-progress/${mangaId}`, (r) =>
+        r.fulfill({ status: 404, contentType: 'application/json', body: '{"error":{"code":"x","message":"x"}}' })
+    );
+    await page.route(`**/api/v1/me/reactions/${mangaId}`, (r) =>
+        r.fulfill({ status: 404, contentType: 'application/json', body: '{"error":{"code":"x","message":"x"}}' })
+    );
+    // Autocomplete suggestions endpoint — keep it empty/fast.
+    await page.route('**/api/v1/tags*', (r) =>
+        r.fulfill({ status: 200, contentType: 'application/json', body: JSON.stringify([]) })
+    );
+    await page.route(`**/api/v1/mangas/${mangaId}`, (r) =>
+        r.fulfill({
+            status: 200,
+            contentType: 'application/json',
+            body: JSON.stringify({
+                id: mangaId, title: 'Berserk', status: 'ongoing', alt_titles: [], description: null,
+                cover_image_path: null, created_at: '2026-01-01T00:00:00Z', updated_at: '2026-01-01T00:00:00Z',
+                authors: [], genres: [], tags: [], content_warnings: [], chapter_storage_bytes: 0
+            })
+        })
+    );
+}
+
+test('adds a tag optimistically before the request resolves', async ({ page }) => {
+    await mockDetail(page);
+
+    let release: () => void = () => {};
+    const gate = new Promise<void>((resolve) => {
+        release = resolve;
+    });
+    await page.route(`**/api/v1/mangas/${mangaId}/tags`, async (route) => {
+        await gate;
+        await route.fulfill({
+            status: 200,
+            contentType: 'application/json',
+            body: JSON.stringify({ id: 'tag1', name: 'action', added_by: 'u1' })
+        });
+    });
+
+    await page.goto(`/manga/${mangaId}`);
+    await expect(page.getByTestId('manga-title')).toHaveText('Berserk');
+
+    await page.getByTestId('tag-input').fill('action');
+    await page.getByTestId('tag-input').press('Enter');
+
+    // Optimistic: the chip shows while the POST is still gated.
+    await expect(page.getByTestId('manga-tags')).toContainText('action');
+
+    release();
+    // Still present after the server confirms (reconciled to the real tag).
+    await expect(page.getByTestId('manga-tags')).toContainText('action');
+    await expect(page.getByTestId('tag-chip-tag1')).toBeVisible();
+});
diff --git a/frontend/package.json b/frontend/package.json
index 1668ffd..9e84fd5 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mangalord-frontend",
-  "version": "0.118.0",
+  "version": "0.118.1",
   "private": true,
   "type": "module",
   "scripts": {
diff --git a/frontend/src/routes/manga/[id]/+page.svelte b/frontend/src/routes/manga/[id]/+page.svelte
index 87f8569..9a9e36b 100644
--- a/frontend/src/routes/manga/[id]/+page.svelte
+++ b/frontend/src/routes/manga/[id]/+page.svelte
@@ -257,18 +257,27 @@
     async function submitTag(name: string) {
         const trimmed = name.trim();
         if (!trimmed || !session.user || tagAddBusy) return;
+        const snapshot = tags;
+        // Show the chip immediately with the typed name; reconcile with the
+        // server ref (which may normalize the name/id) on success. Drop any
+        // existing same-name chip so a re-add doesn't duplicate.
+        const tempId = `optimistic-${crypto.randomUUID()}`;
+        tags = [
+            ...tags.filter((t) => t.name.toLowerCase() !== trimmed.toLowerCase()),
+            { id: tempId, name: trimmed, added_by: session.user.id }
+        ];
+        tagDraft = '';
+        suggestions = [];
+        suggestHighlight = -1;
         tagAddBusy = true;
         tagError = null;
         try {
             const attached = await attachTag(manga.id, trimmed);
-            // If the tag was already attached by someone else, the
-            // server returns 200 + the existing ref — replace any
-            // matching entry to keep local state coherent.
-            tags = [...tags.filter((t) => t.id !== attached.id), attached];
-            tagDraft = '';
-            suggestions = [];
-            suggestHighlight = -1;
+            // Replace the placeholder (and any pre-existing entry the server
+            // may have matched) with the authoritative ref.
+            tags = [...tags.filter((t) => t.id !== tempId && t.id !== attached.id), attached];
         } catch (e) {
+            tags = snapshot;
             tagError = (e as Error).message;
         } finally {
             tagAddBusy = false;