Merge

libs/checkpoint/src/memory.ts

@@ -54,17 +54,7 @@ export class MemorySaver extends BaseCheckpointSaver {
             ];
           })
         );
-        const parentConfig =
-          parentCheckpointId !== undefined
-            ? {
-                configurable: {
-                  thread_id,
-                  checkpoint_ns,
-                  checkpoint_id,
-                },
-              }
-            : undefined;
-        return {
+        const checkpointTuple: CheckpointTuple = {
           config,
           checkpoint: (await this.serde.loadsTyped(
             "json",
@@ -75,8 +65,17 @@ export class MemorySaver extends BaseCheckpointSaver {
             metadata
           )) as CheckpointMetadata,
           pendingWrites,
-          parentConfig,
         };
+        if (parentCheckpointId !== undefined) {
+          checkpointTuple.parentConfig = {
+            configurable: {
+              thread_id,
+              checkpoint_ns,
+              checkpoint_id,
+            },
+          };
+        }
+        return checkpointTuple;
       }
     } else {
       const checkpoints = this.storage[thread_id]?.[checkpoint_ns];
@@ -99,17 +98,7 @@ export class MemorySaver extends BaseCheckpointSaver {
             ];
           })
         );
-        const parentConfig =
-          parentCheckpointId !== undefined
-            ? {
-                configurable: {
-                  thread_id,
-                  checkpoint_ns,
-                  checkpoint_id: parentCheckpointId,
-                },
-              }
-            : undefined;
-        return {
+        const checkpointTuple: CheckpointTuple = {
           config: {
             configurable: {
               thread_id,
@@ -126,8 +115,17 @@ export class MemorySaver extends BaseCheckpointSaver {
             metadata
           )) as CheckpointMetadata,
           pendingWrites,
-          parentConfig,
         };
+        if (parentCheckpointId !== undefined) {
+          checkpointTuple.parentConfig = {
+            configurable: {
+              thread_id,
+              checkpoint_ns,
+              checkpoint_id: parentCheckpointId,
+            },
+          };
+        }
+        return checkpointTuple;
       }
     }
 
@@ -191,7 +189,7 @@ export class MemorySaver extends BaseCheckpointSaver {
           })
         );
 
-        yield {
+        const checkpointTuple: CheckpointTuple = {
           config: {
             configurable: {
               thread_id: threadId,
@@ -205,16 +203,17 @@ export class MemorySaver extends BaseCheckpointSaver {
           )) as Checkpoint,
           metadata,
           pendingWrites,
-          parentConfig: parentCheckpointId
-            ? {
-                configurable: {
-                  thread_id: threadId,
-                  checkpoint_ns: checkpointNamespace,
-                  checkpoint_id: parentCheckpointId,
-                },
-              }
-            : undefined,
         };
+        if (parentCheckpointId !== undefined) {
+          checkpointTuple.parentConfig = {
+            configurable: {
+              thread_id: threadId,
+              checkpoint_ns: checkpointNamespace,
+              checkpoint_id: parentCheckpointId,
+            },
+          };
+        }
+        yield checkpointTuple;
       }
     }
   }

libs/checkpoint/src/serde/jsonplus.ts

@@ -5,7 +5,9 @@ import { SerializerProtocol } from "./base.js";
 
 async function _reviver(value: any): Promise<any> {
   if (value && typeof value === "object") {
-    if (
+    if (value.lc === 2 && value.type === "undefined") {
+      return undefined;
+    } else if (
       value.lc === 2 &&
       value.type === "constructor" &&
       Array.isArray(value.id)
@@ -64,14 +66,19 @@ function _encodeConstructorArgs(
     lc: 2,
     type: "constructor",
     id: [constructor.name],
-    method,
+    method: method ?? null,
     args: args ?? [],
     kwargs: kwargs ?? {},
   };
 }
 
 function _default(_key: string, obj: any): any {
-  if (obj instanceof Set || obj instanceof Map) {
+  if (obj === undefined) {
+    return {
+      lc: 2,
+      type: "undefined",
+    };
+  } else if (obj instanceof Set || obj instanceof Map) {
     return _encodeConstructorArgs(obj.constructor, undefined, [
       Array.from(obj),
     ]);

libs/checkpoint/src/serde/tests/jsonplus.test.ts

@@ -3,7 +3,7 @@ import { AIMessage, HumanMessage } from "@langchain/core/messages";
 import { uuid6 } from "../../id.js";
 import { JsonPlusSerializer } from "../jsonplus.js";
 
-const value = {
+const complexValue = {
   number: 1,
   id: uuid6(-1),
   error: new Error("test error"),
@@ -18,6 +18,7 @@ const value = {
     new Error("nestedfoo"),
     5,
     true,
+    null,
     false,
     {
       a: "b",
@@ -26,12 +27,27 @@ const value = {
   ],
   object: {
     messages: [new HumanMessage("hey there"), new AIMessage("hi how are you")],
+    nestedNullVal: null,
+    emptyString: "",
   },
+  emptyString: "",
+  nullVal: null,
 };
 
-it("should serialize and deserialize various data types", async () => {
-  const serde = new JsonPlusSerializer();
-  const [type, serialized] = serde.dumpsTyped(value);
-  const deserialized = await serde.loadsTyped(type, serialized);
-  expect(deserialized).toEqual(value);
-});
+const VALUES = [
+  ["undefined", undefined],
+  ["null", null],
+  ["empty string", ""],
+  ["simple string", "foobar"],
+  ["various data types", complexValue],
+] satisfies [string, unknown][];
+
+it.each(VALUES)(
+  "should serialize and deserialize %s",
+  async (_description, value) => {
+    const serde = new JsonPlusSerializer();
+    const [type, serialized] = serde.dumpsTyped(value);
+    const deserialized = await serde.loadsTyped(type, serialized);
+    expect(deserialized).toEqual(value);
+  }
+);

libs/langgraph/src/pregel/index.ts

@@ -457,7 +457,6 @@ export class Pregel<
         writers.length > 1 ? RunnableSequence.from(writers as any) : writers[0],
       writes: [],
       triggers: [INTERRUPT],
-      config: undefined,
       id: uuid5(INTERRUPT, checkpoint.id),
     };
 

libs/langgraph/src/pregel/loop.ts

@@ -302,7 +302,7 @@ export class PregelLoop {
         : mapOutputValues(outputKeys, writes, this.channels).next().value;
       await this._putCheckpoint({
         source: "loop",
-        writes: metadataWrites,
+        writes: metadataWrites ?? null,
       });
       // after execution, check if we should interrupt
       if (shouldInterrupt(this.checkpoint, interruptAfter, this.tasks)) {
@@ -456,7 +456,10 @@ export class PregelLoop {
         this.checkpointerGetNextVersion
       );
       // save input checkpoint
-      await this._putCheckpoint({ source: "input", writes: this.input });
+      await this._putCheckpoint({
+        source: "input",
+        writes: this.input ?? null,
+      });
     }
     // done with input
     this.input = isResuming ? INPUT_RESUMING : INPUT_DONE;

libs/langgraph/src/pregel/types.ts

@@ -87,7 +87,7 @@ export interface PregelExecutableTask<
   readonly input: unknown;
   readonly proc: Runnable;
   readonly writes: PendingWrite<C>[];
-  readonly config: RunnableConfig | undefined;
+  readonly config?: RunnableConfig;
   readonly triggers: Array<string>;
   readonly retry_policy?: RetryPolicy;
   readonly id: string;