fix: remove EventChain fast path to preserve per-spec event actions

The fast path grouped backend-only EventSpecs into a single addEvents
call, which lost per-spec event actions like individual debounce values.
Each EventSpec now renders its own addEvents call, and chain-level actions
use applyEventActions consistently.

Author: FarhanAliRaza

reflex/event.py

@@ -2115,22 +2115,6 @@ def create(
             raise ValueError(msg)
         assert invocation is not None
 
-        if not any(isinstance(event, FunctionVar) for event in value.events):
-            return cls(
-                _js_expr="",
-                _var_type=EventChain,
-                _var_data=_var_data,
-                _args=FunctionArgs(arg_def),
-                _return_expr=invocation.call(
-                    LiteralVar.create([
-                        LiteralVar.create(event) for event in value.events
-                    ]),
-                    arg_def_expr,
-                    value.event_actions,
-                ),
-                _var_value=value,
-            )
-
         call_args = arg_vars if sig.parameters else (Var(_js_expr="...args"),)
         statements = [
             (

tests/units/test_event.py

@@ -760,23 +760,52 @@ def do_a_thing(self):
     assert isinstance(button.event_triggers["on_click"], EventChain)
 
 
-def test_event_chain_codegen_uses_fast_path_for_backend_only_events():
-    """Backend-only chains should render through a single addEvents call."""
+def test_event_chain_codegen_preserves_backend_event_actions_per_spec():
+    """Backend-only chains should keep per-spec event actions separate."""
 
     class FastPathState(BaseState):
         @event
-        def do_a_thing(self):
+        def do_a_thing(self, value: str):
             pass
 
     chain = EventChain.create(
-        [FastPathState.do_a_thing, FastPathState.do_a_thing],
+        [
+            FastPathState.do_a_thing("first x 1000").debounce(1000),
+            FastPathState.do_a_thing("second x 200").debounce(200),
+        ],
         args_spec=lambda: (),
-        event_actions={"preventDefault": True},
     )
     rendered = str(LiteralVar.create(chain))
 
     assert "applyEventActions(" not in rendered
-    assert rendered.count("addEvents(") == 1
+    assert rendered.count("addEvents(") == 2
+    assert '["debounce"] : 1000' in rendered
+    assert '["debounce"] : 200' in rendered
+    assert rendered.index("first x 1000") < rendered.index("second x 200")
+
+
+def test_event_chain_codegen_keeps_chain_event_actions_for_backend_only_events():
+    """Chain-level actions should still wrap backend-only event chains."""
+
+    class FastPathState(BaseState):
+        @event
+        def do_a_thing(self, value: str):
+            pass
+
+    chain = EventChain.create(
+        [
+            FastPathState.do_a_thing("first x 1000").debounce(1000),
+            FastPathState.do_a_thing("second x 200").debounce(200),
+        ],
+        args_spec=lambda: (),
+        event_actions={"preventDefault": True},
+    )
+    rendered = str(LiteralVar.create(chain))
+
+    assert "applyEventActions(" in rendered
+    assert rendered.count("addEvents(") == 2
+    assert '["debounce"] : 1000' in rendered
+    assert '["debounce"] : 200' in rendered
     assert '["preventDefault"] : true' in rendered
 
 

tests/units/utils/test_format.py

@@ -53,7 +53,7 @@ def make_timeout_logger():
 
 
 def test_format_prop_event_chain_pure_eventspec_grouped():
-    """Pure EventSpec chains should stay grouped in one addEvents call."""
+    """Pure EventSpec chains should preserve order with separate addEvents calls."""
     chain = EventChain(
         events=[
             EventSpec(handler=EventHandler(fn=mock_event)),
@@ -63,8 +63,9 @@ def test_format_prop_event_chain_pure_eventspec_grouped():
     )
 
     assert format.format_prop(LiteralVar.create(chain)) == (
-        '((_e) => (addEvents([(ReflexEvent("mock_event", ({  }), ({  }))), '
-        '(ReflexEvent("mock_event_two", ({  }), ({  })))], [_e], ({  }))))'
+        '((_e) => {(addEvents([(ReflexEvent("mock_event", ({  }), ({  })))], '
+        '[_e], ({  })));(addEvents([(ReflexEvent("mock_event_two", ({  }), '
+        "({  })))], [_e], ({  })));})"
     )
 
 
@@ -510,7 +511,7 @@ def test_format_match(
                 args_spec=no_args_event_spec,
                 event_actions={"stopPropagation": True},
             ),
-            '((...args) => (addEvents([(ReflexEvent("mock_event", ({  }), ({  })))], args, ({ ["stopPropagation"] : true }))))',
+            '((...args) => (applyEventActions((() => {(addEvents([(ReflexEvent("mock_event", ({  }), ({  })))], args, ({  })));}), ({ ["stopPropagation"] : true }), ...args)))',
         ),
         (
             EventChain(
@@ -530,7 +531,7 @@ def test_format_match(
                 args_spec=no_args_event_spec,
                 event_actions={"preventDefault": True},
             ),
-            '((...args) => (addEvents([(ReflexEvent("mock_event", ({  }), ({  })))], args, ({ ["preventDefault"] : true }))))',
+            '((...args) => (applyEventActions((() => {(addEvents([(ReflexEvent("mock_event", ({  }), ({  })))], args, ({  })));}), ({ ["preventDefault"] : true }), ...args)))',
         ),
         ({"a": "red", "b": "blue"}, '({ ["a"] : "red", ["b"] : "blue" })'),
         (Var(_js_expr="var", _var_type=int).guess_type(), "var"),