diff --git a/ui/src/components/conversation.rs b/ui/src/components/conversation.rs
index bdae7bb1..d54ffe34 100644
--- a/ui/src/components/conversation.rs
+++ b/ui/src/components/conversation.rs
@@ -1808,14 +1808,16 @@ fn MessageGroupComponent(
                                                     // Message body, wrapped in a padding container so the
                                                     // "(edited)" indicator can sit inline at the trailing
                                                     // edge of the body text rather than as a separate
-                                                    // flex-column row. `break-words` ensures long URLs and
-                                                    // unbreakable tokens wrap instead of clipping (the
-                                                    // bubble has `overflow-hidden` to keep the reply strip
-                                                    // contained).
+                                                    // flex-column row. `[overflow-wrap:anywhere]` ensures
+                                                    // long URLs and unbreakable tokens wrap instead of
+                                                    // forcing the bubble past `max-w-prose`. `anywhere` is
+                                                    // stricter than `break-word`: it also lowers the
+                                                    // element's min-content so flex/grid parents can shrink
+                                                    // the bubble to fit.
                                                     div {
                                                         class: "px-3 py-2 min-w-0",
                                                         div {
-                                                            class: "prose prose-sm dark:prose-invert max-w-none break-words",
+                                                            class: "prose prose-sm dark:prose-invert max-w-none [overflow-wrap:anywhere]",
                                                             dangerous_inner_html: "{msg.content_html}"
                                                         }
                                                         if msg.edited {
diff --git a/ui/src/example_data.rs b/ui/src/example_data.rs
index 41fb5a01..e8552e98 100644
--- a/ui/src/example_data.rs
+++ b/ui/src/example_data.rs
@@ -355,6 +355,25 @@ fn add_example_messages(
         messages.messages.push(reply_msg);
     }
 
+    // Add a message containing an unbreakable long URL so the bubble width
+    // regression for #212 is exercised by Playwright.
+    {
+        let (long_url_author_id, long_url_signing_key) = authors[0];
+        current_time_ms += 30_000;
+        let long_url_msg = AuthorizedMessageV1::new(
+            MessageV1 {
+                room_owner: *owner_id,
+                author: long_url_author_id,
+                time: get_time_from_millis(current_time_ms),
+                content: RoomMessageBody::public(
+                    "https://example.com/longlongurlpathlonglongurlpathlonglongurlpathlonglongurlpathlonglongurlpathlonglongurlpathlonglongurlpathlonglongurlpathlonglongurlpathlonglongurlpath".to_string(),
+                ),
+            },
+            long_url_signing_key,
+        );
+        messages.messages.push(long_url_msg);
+    }
+
     // Add reactions to messages from OTHER members (not owner)
     // Rule: One reaction per user per message
     // In "Your Private Room" the owner IS self, so this shows self reacting to others
diff --git a/ui/tests/message-layout.spec.ts b/ui/tests/message-layout.spec.ts
index 716fa99d..8bf73cf9 100644
--- a/ui/tests/message-layout.spec.ts
+++ b/ui/tests/message-layout.spec.ts
@@ -298,3 +298,67 @@ test.describe("Reply strip keyboard accessibility (#210)", () => {
       .toBeGreaterThan(0);
   });
 });
+
+// #212: a message containing an unbreakable long string (e.g. a long URL)
+// must wrap inside the bubble without overflowing. `overflow-wrap: break-word`
+// (the `break-words` utility) inserts soft breaks when content would
+// otherwise overflow, but does NOT lower min-content sizing — so an ancestor
+// `min-w-0` flex parent still gets stretched by the long token. Switching to
+// `overflow-wrap: anywhere` also lowers min-content, which is what lets the
+// bubble actually shrink to fit.
+test.describe("Long unbreakable content (#212)", () => {
+  test.use({ viewport: { width: 1024, height: 900 } });
+
+  test("bubble with long URL wraps and does not cause horizontal overflow", async ({
+    page,
+  }) => {
+    await page.goto("/");
+    await waitForApp(page);
+    await selectRoom(page, "Your Private Room");
+
+    const longTokenBubble = page
+      .locator(".max-w-prose")
+      .filter({ hasText: "longlongurlpath" })
+      .first();
+    await expect(longTokenBubble).toBeVisible({ timeout: 10_000 });
+    await longTokenBubble.scrollIntoViewIfNeeded();
+
+    // Core assertion: the inner prose body must not overflow its own box —
+    // i.e. the long URL must actually wrap. If `overflow-wrap` fails to
+    // apply, the <a> element's min-content exceeds the parent width and
+    // scrollWidth > clientWidth.
+    const proseOverflow = await longTokenBubble.evaluate((el) => {
+      const prose = el.querySelector(".max-w-none") as HTMLElement | null;
+      if (!prose) return { ok: false, reason: "no prose div" };
+      const a = prose.querySelector("a") as HTMLElement | null;
+      const aRect = a?.getBoundingClientRect();
+      const pRect = prose.getBoundingClientRect();
+      return {
+        ok: true,
+        proseScroll: prose.scrollWidth,
+        proseClient: prose.clientWidth,
+        aWidth: aRect?.width ?? 0,
+        proseWidth: pRect.width,
+      };
+    });
+    expect(proseOverflow.ok).toBe(true);
+    // The prose content must not overflow its own container.
+    expect(proseOverflow.proseScroll).toBeLessThanOrEqual(
+      proseOverflow.proseClient + 1
+    );
+    // And the rendered <a> must fit inside the prose box (i.e. the URL
+    // wrapped rather than forcing the link to be wider than its parent).
+    expect(proseOverflow.aWidth).toBeLessThanOrEqual(
+      proseOverflow.proseWidth + 1
+    );
+
+    // Defense in depth: no horizontal overflow on the document. The
+    // original regression screenshot showed the long-URL bubble pushing
+    // the chat column wider than its sibling bubbles.
+    const docOverflow = await page.evaluate(() => ({
+      scroll: document.documentElement.scrollWidth,
+      client: document.documentElement.clientWidth,
+    }));
+    expect(docOverflow.scroll).toBeLessThanOrEqual(docOverflow.client + 1);
+  });
+});