diff --git a/src/adapters/discord_bot/views/task_modals.py b/src/adapters/discord_bot/views/task_modals.py
index cfbb8ad..bac361f 100644
--- a/src/adapters/discord_bot/views/task_modals.py
+++ b/src/adapters/discord_bot/views/task_modals.py
@@ -71,9 +71,12 @@ async def on_submit(self, interaction: discord.Interaction) -> None:
             keep_archived = (task.status == TaskStatus.COMPLETED or task.is_archived) if task else False
             async with unarchive_thread_if_needed(thread, keep_archived=keep_archived):
                 await interaction.response.send_message(
-                    f"✅ Note added to **{self.short_id}** by <@{interaction.user.id}>:\n> {note_text}",
-                    ephemeral=False,
+                    f"✅ Note added to **{self.short_id}**.",
+                    ephemeral=True,
                 )
+                from src.adapters.discord_bot.menu_manager import menu_manager
+
+                menu_manager.schedule_toast_dismissal(interaction, delay=6.0)
         except Exception as e:
             await send_interaction_error(
                 interaction, e, f"adding note to task '{self.short_id}'", logger, ephemeral=True
diff --git a/tests/test_discord_thread_lifecycle.py b/tests/test_discord_thread_lifecycle.py
index f651611..909aeae 100644
--- a/tests/test_discord_thread_lifecycle.py
+++ b/tests/test_discord_thread_lifecycle.py
@@ -465,6 +465,49 @@ async def test_task_note_modal_completed_archived_thread(services):
     interaction.response.send_message.assert_awaited_once()
 
 
+@pytest.mark.asyncio
+async def test_task_note_modal_responds_ephemerally_to_prevent_duplicate_activity(services, monkeypatch):
+    """Verify TaskNoteModal acknowledges ephemerally so thread does not get duplicate public messages."""
+    from src.adapters.discord_bot.menu_manager import menu_manager
+    from src.adapters.discord_bot.views.task_modals import TaskNoteModal
+
+    scheduled = []
+    monkeypatch.setattr(menu_manager, "schedule_toast_dismissal", lambda target, delay=6.0: scheduled.append(target))
+
+    proj_srv = services["project"]
+    task_srv = services["task"]
+    guild_id = 11224455
+
+    project = await proj_srv.create_project(guild_id=guild_id, name="Notes Single Post Test", prefix="NOT2")
+    task = await task_srv.create_task(
+        guild_id=guild_id,
+        title="Task for Single Note Post",
+        creator_discord_id=1001,
+        project_id=project.id,
+    )
+
+    modal = TaskNoteModal(
+        task_id=task.id,
+        short_id=task.short_id,
+        task_service=task_srv,
+    )
+    modal.note_input._value = "Checking single activity log."
+
+    interaction = MagicMock(spec=discord.Interaction)
+    interaction.user = MagicMock()
+    interaction.user.id = 1001
+    interaction.channel = MagicMock(spec=discord.Thread)
+    interaction.response = MagicMock()
+    interaction.response.send_message = AsyncMock()
+
+    await modal.on_submit(interaction)
+
+    interaction.response.send_message.assert_awaited_once()
+    assert interaction.response.send_message.call_args.kwargs.get("ephemeral") is True
+    assert len(scheduled) == 1
+    assert scheduled[0] is interaction
+
+
 @pytest.mark.asyncio
 async def test_task_edit_modal_completed_archived_thread(services):
     """Verify editing details of a completed/archived task unarchives then re-archives thread."""