Replace get_catch w is_available

libs/langgraph/langgraph/channels/any_value.py

@@ -1,8 +1,9 @@
-from typing import Generic, Optional, Sequence, Type
+from typing import Any, Generic, Optional, Sequence, Type
 
 from typing_extensions import Self
 
 from langgraph.channels.base import BaseChannel, Value
+from langgraph.constants import MISSING
 from langgraph.errors import EmptyChannelError
 
 
@@ -12,6 +13,10 @@ class AnyValue(Generic[Value], BaseChannel[Value, Value, Value]):
 
     __slots__ = ("typ", "value")
 
+    def __init__(self, typ: Any, key: str = "") -> None:
+        super().__init__(typ, key)
+        self.value = MISSING
+
     def __eq__(self, value: object) -> bool:
         return isinstance(value, AnyValue)
 
@@ -34,17 +39,19 @@ class AnyValue(Generic[Value], BaseChannel[Value, Value, Value]):
 
     def update(self, values: Sequence[Value]) -> bool:
         if len(values) == 0:
-            try:
-                del self.value
-                return True
-            except AttributeError:
+            if self.value is MISSING:
                 return False
+            else:
+                self.value = MISSING
+                return True
 
         self.value = values[-1]
         return True
 
     def get(self) -> Value:
-        try:
-            return self.value
-        except AttributeError:
+        if self.value is MISSING:
             raise EmptyChannelError()
+        return self.value
+
+    def is_available(self) -> bool:
+        return self.value is not MISSING

libs/langgraph/langgraph/channels/base.py

@@ -3,7 +3,6 @@ from typing import Any, Generic, Optional, Sequence, TypeVar
 
 from typing_extensions import Self
 
-from langgraph.constants import MISSING
 from langgraph.errors import EmptyChannelError, InvalidUpdateError
 
 Value = TypeVar("Value")
@@ -65,13 +64,16 @@ class BaseChannel(Generic[Value, Update, C], ABC):
         """
         return False
 
-    def get_catch(self) -> Value:
-        """Return the current value of the channel, or MISSING if the channel
-        is empty. Subclasses can override to skip the EmptyChannelError check."""
+    def is_available(self) -> bool:
+        """Return True if the channel is available (not empty), False otherwise.
+        Subclasses should override this method to provide a more efficient
+        implementation than calling get() and catching EmptyChannelError.
+        """
         try:
-            return self.get()
+            self.get()
+            return True
         except EmptyChannelError:
-            return MISSING
+            return False
 
 
 __all__ = [

libs/langgraph/langgraph/channels/binop.py

@@ -10,6 +10,7 @@ from typing import (
 from typing_extensions import NotRequired, Required, Self
 
 from langgraph.channels.base import BaseChannel, Value
+from langgraph.constants import MISSING
 from langgraph.errors import EmptyChannelError
 
 
@@ -51,7 +52,7 @@ class BinaryOperatorAggregate(Generic[Value], BaseChannel[Value, Value, Value]):
         try:
             self.value = typ()
         except Exception:
-            pass
+            self.value = MISSING
 
     def __eq__(self, value: object) -> bool:
         return isinstance(value, BinaryOperatorAggregate) and (
@@ -81,7 +82,7 @@ class BinaryOperatorAggregate(Generic[Value], BaseChannel[Value, Value, Value]):
     def update(self, values: Sequence[Value]) -> bool:
         if not values:
             return False
-        if not hasattr(self, "value"):
+        if self.value is MISSING:
             self.value = values[0]
             values = values[1:]
         for value in values:
@@ -89,7 +90,9 @@ class BinaryOperatorAggregate(Generic[Value], BaseChannel[Value, Value, Value]):
         return True
 
     def get(self) -> Value:
-        try:
-            return self.value
-        except AttributeError:
+        if self.value is MISSING:
             raise EmptyChannelError()
+        return self.value
+
+    def is_available(self) -> bool:
+        return self.value is not MISSING

libs/langgraph/langgraph/channels/dynamic_barrier_value.py

@@ -85,6 +85,9 @@ class DynamicBarrierValue(
             raise EmptyChannelError()
         return None
 
+    def is_available(self) -> bool:
+        return self.seen == self.names
+
     def consume(self) -> bool:
         if self.seen == self.names:
             self.seen = set()

libs/langgraph/langgraph/channels/ephemeral_value.py

@@ -57,5 +57,5 @@ class EphemeralValue(Generic[Value], BaseChannel[Value, Value, Value]):
             raise EmptyChannelError()
         return self.value
 
-    def get_catch(self) -> Value:
-        return self.value
+    def is_available(self) -> bool:
+        return self.value is not MISSING

libs/langgraph/langgraph/channels/last_value.py

@@ -59,5 +59,5 @@ class LastValue(Generic[Value], BaseChannel[Value, Value, Value]):
             raise EmptyChannelError()
         return self.value
 
-    def get_catch(self) -> Value:
-        return self.value
+    def is_available(self) -> bool:
+        return self.value is not MISSING

libs/langgraph/langgraph/channels/named_barrier_value.py

@@ -60,6 +60,9 @@ class NamedBarrierValue(Generic[Value], BaseChannel[Value, Value, set[Value]]):
             raise EmptyChannelError()
         return None
 
+    def is_available(self) -> bool:
+        return self.seen == self.names
+
     def consume(self) -> bool:
         if self.seen == self.names:
             self.seen = set()

libs/langgraph/langgraph/channels/topic.py

@@ -75,3 +75,6 @@ class Topic(
             return list(self.values)
         else:
             raise EmptyChannelError
+
+    def is_available(self) -> bool:
+        return bool(self.values)

libs/langgraph/langgraph/channels/untracked_value.py

@@ -54,5 +54,5 @@ class UntrackedValue(Generic[Value], BaseChannel[Value, Value, Value]):
             raise EmptyChannelError()
         return self.value
 
-    def get_catch(self) -> Value:
-        return self.value
+    def is_available(self) -> bool:
+        return self.value is not MISSING

libs/langgraph/langgraph/pregel/algo.py

@@ -48,7 +48,6 @@ from langgraph.constants import (
     EMPTY_SEQ,
     ERROR,
     INTERRUPT,
-    MISSING,
     NO_WRITES,
     NS_END,
     NS_SEP,
@@ -650,7 +649,7 @@ def prepare_single_task(
         if triggers := sorted(
             chan
             for chan in proc.triggers
-            if channels[chan].get_catch() is not MISSING
+            if channels[chan].is_available()
             and checkpoint["channel_versions"].get(chan, null_version)  # type: ignore[operator]
             > seen.get(chan, null_version)
         ):