feat(js): Adds developer role as a system role alias

langchain-core/src/messages/base.ts

@@ -34,6 +34,7 @@ export type MessageType =
   | "human"
   | "ai"
   | "generic"
+  | "developer"
   | "system"
   | "function"
   | "tool"

langchain-core/src/messages/tests/base_message.test.ts

@@ -346,6 +346,7 @@ describe("Message like coercion", () => {
         role: "system",
         content: "6",
       },
+      { role: "developer", content: "6.1" },
       {
         role: "user",
         content: [{ type: "image_url", image_url: { url: "7.1" } }],
@@ -374,6 +375,13 @@ describe("Message like coercion", () => {
       new SystemMessage({
         id: "foobar",
         content: "6",
+        additional_kwargs: {},
+      }),
+      new SystemMessage({
+        content: "6.1",
+        additional_kwargs: {
+          __openai_role__: "developer",
+        },
       }),
       new HumanMessage({
         content: [{ type: "image_url", image_url: { url: "7.1" } }],

langchain-core/src/messages/transformers.ts

@@ -906,6 +906,10 @@ const _MSG_CHUNK_MAP: Record<
     message: SystemMessage,
     messageChunk: SystemMessageChunk,
   },
+  developer: {
+    message: SystemMessage,
+    messageChunk: SystemMessageChunk,
+  },
   tool: {
     message: ToolMessage,
     messageChunk: ToolMessageChunk,
@@ -977,6 +981,25 @@ function _switchTypeToMessage(
         msg = new SystemMessage(fields);
       }
       break;
+    case "developer":
+      if (returnChunk) {
+        chunk = new SystemMessageChunk({
+          ...fields,
+          additional_kwargs: {
+            ...fields.additional_kwargs,
+            __openai_role__: "developer",
+          },
+        });
+      } else {
+        msg = new SystemMessage({
+          ...fields,
+          additional_kwargs: {
+            ...fields.additional_kwargs,
+            __openai_role__: "developer",
+          },
+        });
+      }
+      break;
     case "tool":
       if ("tool_call_id" in fields) {
         if (returnChunk) {

langchain-core/src/messages/utils.ts

@@ -107,6 +107,14 @@ function _constructMessageFromParams(
     return new AIMessage({ ...other, tool_calls });
   } else if (type === "system") {
     return new SystemMessage(rest);
+  } else if (type === "developer") {
+    return new SystemMessage({
+      ...rest,
+      additional_kwargs: {
+        ...rest.additional_kwargs,
+        __openai_role__: "developer",
+      },
+    });
   } else if (type === "tool" && "tool_call_id" in rest) {
     return new ToolMessage({
       ...rest,
@@ -117,7 +125,7 @@ function _constructMessageFromParams(
   } else {
     const error = addLangChainErrorFields(
       new Error(
-        `Unable to coerce message from array: only human, AI, system, or tool message coercion is currently supported.\n\nReceived: ${JSON.stringify(
+        `Unable to coerce message from array: only human, AI, system, developer, or tool message coercion is currently supported.\n\nReceived: ${JSON.stringify(
           params,
           null,
           2

langchain-core/src/prompts/tests/chat.test.ts

@@ -373,7 +373,7 @@ test("Test MessagesPlaceholder not optional with invalid input should throw", as
       badInput,
       null,
       2
-    )}\n\nAdditional message: Unable to coerce message from array: only human, AI, system, or tool message coercion is currently supported.`
+    )}\n\nAdditional message: Unable to coerce message from array: only human, AI, system, developer, or tool message coercion is currently supported.`
   );
 });