diff --git a/decart/realtime/webrtc_connection.py b/decart/realtime/webrtc_connection.py
index 12f53ed..a51e8ed 100644
--- a/decart/realtime/webrtc_connection.py
+++ b/decart/realtime/webrtc_connection.py
@@ -62,6 +62,10 @@ def __init__(
         self._local_track: Optional[MediaStreamTrack] = None
         self._model_name: Optional[str] = None
         self._connection_error: Optional[str] = None
+        # Per-connect() dedup: _handle_error and connect()'s except branches both
+        # may see the same error; whichever fires first flips this to True and the
+        # other skips. Reset at the top of every connect() call.
+        self._on_error_fired: bool = False
 
     async def connect(
         self,
@@ -77,6 +81,7 @@ async def connect(
             self._local_track = local_track
             self._model_name = model_name
             self._connection_error = None
+            self._on_error_fired = False
 
             await self._set_state("connecting")
 
@@ -116,10 +121,18 @@ async def connect(
 
             raise TimeoutError("Connection timeout")
 
+        except WebRTCError as e:
+            logger.error(f"Connection failed: {e}")
+            await self._set_state("disconnected")
+            if self._on_error and not self._on_error_fired:
+                self._on_error_fired = True
+                self._on_error(e)
+            raise
         except Exception as e:
             logger.error(f"Connection failed: {e}")
             await self._set_state("disconnected")
-            if self._on_error:
+            if self._on_error and not self._on_error_fired:
+                self._on_error_fired = True
                 self._on_error(e)
             raise WebRTCError(str(e), cause=e)
 
@@ -394,6 +407,7 @@ def _handle_error(self, message: ErrorMessage) -> None:
         self._resolve_pending_waits(message.error)
 
         if self._on_error:
+            self._on_error_fired = True
             self._on_error(error)
 
     def register_image_set_wait(self) -> tuple[asyncio.Event, dict]:
diff --git a/tests/test_realtime_unit.py b/tests/test_realtime_unit.py
index b748eed..d13e82d 100644
--- a/tests/test_realtime_unit.py
+++ b/tests/test_realtime_unit.py
@@ -1354,3 +1354,111 @@ async def inject_error_soon():
                 )
     finally:
         injector.cancel()
+
+
+@pytest.mark.asyncio
+async def test_connect_does_not_double_wrap_webrtc_error():
+    """WebRTCError raised inside connect() re-raises as-is — no nested cause, no duplicate on_error."""
+    from decart.realtime.webrtc_connection import WebRTCConnection
+    from decart.errors import WebRTCError
+
+    errors: list[Exception] = []
+    connection = WebRTCConnection(on_error=lambda e: errors.append(e))
+
+    connection._setup_peer_connection = AsyncMock()  # type: ignore[assignment]
+    connection._create_and_send_offer = AsyncMock()  # type: ignore[assignment]
+
+    async def _noop_receive():
+        await asyncio.sleep(60)
+
+    connection._receive_messages = _noop_receive  # type: ignore[assignment]
+
+    fake_ws = MagicMock()
+    fake_ws.closed = False
+    fake_ws.close = AsyncMock()
+
+    mock_session = MagicMock()
+    mock_session.closed = False
+    mock_session.close = AsyncMock()
+    mock_session.ws_connect = AsyncMock(return_value=fake_ws)
+
+    async def inject_error_soon():
+        await asyncio.sleep(0.15)
+        # Simulate _handle_error having run: it sets _connection_error, fires
+        # on_error, and marks _on_error_fired so connect() doesn't double-fire.
+        connection._connection_error = "Server at capacity. Please try again later."
+        errors.append(WebRTCError("Server at capacity. Please try again later."))
+        connection._on_error_fired = True
+
+    injector = asyncio.create_task(inject_error_soon())
+
+    try:
+        with patch(
+            "decart.realtime.webrtc_connection.aiohttp.ClientSession",
+            return_value=mock_session,
+        ):
+            with pytest.raises(WebRTCError) as exc_info:
+                await connection.connect(
+                    url="https://example.com/ws",
+                    local_track=None,
+                    timeout=10.0,
+                )
+    finally:
+        injector.cancel()
+
+    assert exc_info.value.message == "Server at capacity. Please try again later."
+    assert not isinstance(exc_info.value.cause, WebRTCError)
+    assert len(errors) == 1, (
+        "connect()'s WebRTCError handler must not fire on_error again when _handle_error "
+        f"already did; got {errors!r}"
+    )
+
+
+@pytest.mark.asyncio
+async def test_connect_direct_raise_fires_on_error_once():
+    """Direct-raise WebRTCError paths (e.g. ack timeouts) must fire on_error exactly once."""
+    from decart.realtime.webrtc_connection import WebRTCConnection
+    from decart.errors import WebRTCError
+
+    errors: list[Exception] = []
+    connection = WebRTCConnection(on_error=lambda e: errors.append(e))
+
+    async def _raise_ack_timeout(prompt, timeout=15.0):
+        raise WebRTCError("Initial prompt acknowledgment timed out")
+
+    connection._send_initial_prompt_and_wait = _raise_ack_timeout  # type: ignore[assignment]
+    connection._setup_peer_connection = AsyncMock()  # type: ignore[assignment]
+    connection._create_and_send_offer = AsyncMock()  # type: ignore[assignment]
+
+    async def _noop_receive():
+        await asyncio.sleep(60)
+
+    connection._receive_messages = _noop_receive  # type: ignore[assignment]
+
+    fake_ws = MagicMock()
+    fake_ws.closed = False
+    fake_ws.close = AsyncMock()
+
+    mock_session = MagicMock()
+    mock_session.closed = False
+    mock_session.close = AsyncMock()
+    mock_session.ws_connect = AsyncMock(return_value=fake_ws)
+
+    with patch(
+        "decart.realtime.webrtc_connection.aiohttp.ClientSession",
+        return_value=mock_session,
+    ):
+        with pytest.raises(WebRTCError) as exc_info:
+            await connection.connect(
+                url="https://example.com/ws",
+                local_track=None,
+                timeout=10.0,
+                initial_prompt={"text": "hello", "enhance": True},
+            )
+
+    assert exc_info.value.message == "Initial prompt acknowledgment timed out"
+    assert not isinstance(exc_info.value.cause, WebRTCError)
+    assert (
+        len(errors) == 1
+    ), f"on_error should fire exactly once for direct-raise paths; got {errors!r}"
+    assert errors[0] is exc_info.value