fix(aws): inference config and system message | ChatBedrockConverse

.changeset/few-lemons-love.md

@@ -0,0 +1,5 @@
+---
+"@langchain/aws": patch
+---
+
+fix(aws): conditional inference config and system message | ChatBedrockConverse

libs/providers/langchain-aws/src/chat_models.ts

@@ -814,13 +814,26 @@ export class ChatBedrockConverse
           : undefined,
       };
     }
+    const candidateInferenceConfig: NonNullable<
+      ConverseCommandParams["inferenceConfig"]
+    > = {
+      maxTokens: this.maxTokens,
+      temperature: this.temperature,
+      topP: this.topP,
+      stopSequences: options?.stop,
+    };
+
+    const hasInferenceValues =
+      candidateInferenceConfig.maxTokens !== undefined ||
+      candidateInferenceConfig.temperature !== undefined ||
+      candidateInferenceConfig.topP !== undefined ||
+      (Array.isArray(candidateInferenceConfig.stopSequences) &&
+        candidateInferenceConfig.stopSequences.length > 0);
+
     return {
-      inferenceConfig: {
-        maxTokens: this.maxTokens,
-        temperature: this.temperature,
-        topP: this.topP,
-        stopSequences: options?.stop,
-      },
+      inferenceConfig: hasInferenceValues
+        ? candidateInferenceConfig
+        : undefined,
       toolConfig,
       additionalModelRequestFields:
         this.additionalModelRequestFields ??
@@ -870,7 +883,9 @@ export class ChatBedrockConverse
     const command = new ConverseCommand({
       modelId: this.model,
       messages: converseMessages,
-      system: converseSystem,
+      ...(Array.isArray(converseSystem) && converseSystem.length > 0
+        ? { system: converseSystem }
+        : {}),
       requestMetadata: options.requestMetadata,
       ...params,
     });
@@ -911,7 +926,9 @@ export class ChatBedrockConverse
     const command = new ConverseStreamCommand({
       modelId: this.model,
       messages: converseMessages,
-      system: converseSystem,
+      ...(Array.isArray(converseSystem) && converseSystem.length > 0
+        ? { system: converseSystem }
+        : {}),
       requestMetadata: options.requestMetadata,
       ...params,
     });

libs/providers/langchain-aws/src/tests/chat_models.invocation.test.ts

@@ -0,0 +1,308 @@
+import { describe, expect, test, vi } from "vitest";
+import { HumanMessage, SystemMessage } from "@langchain/core/messages";
+import { ChatBedrockConverse } from "../chat_models.js";
+import type {
+  ConverseCommandInput,
+  ConverseStreamCommandInput,
+} from "@aws-sdk/client-bedrock-runtime";
+
+vi.mock("@aws-sdk/client-bedrock-runtime", () => {
+  class ConverseCommand {
+    input: ConverseCommandInput;
+    static lastInput: ConverseCommandInput;
+    constructor(input: ConverseCommandInput) {
+      this.input = input;
+      ConverseCommand.lastInput = input;
+    }
+  }
+  class ConverseStreamCommand {
+    input: ConverseStreamCommandInput;
+    static lastInput: ConverseStreamCommandInput;
+    constructor(input: ConverseStreamCommandInput) {
+      this.input = input;
+      ConverseStreamCommand.lastInput = input;
+    }
+  }
+  class BedrockRuntimeClient {
+    async send(command: unknown) {
+      // Non-stream path
+      if (
+        (command as { constructor?: unknown })?.constructor === ConverseCommand
+      ) {
+        return {
+          output: {
+            message: {
+              role: "assistant",
+              content: [{ text: "Response" }],
+            },
+          },
+          usage: {
+            inputTokens: 10,
+            outputTokens: 5,
+            totalTokens: 15,
+          },
+        };
+      }
+      // Stream path
+      if (
+        (command as { constructor?: unknown })?.constructor ===
+        ConverseStreamCommand
+      ) {
+        return {
+          stream: (async function* () {
+            yield {
+              contentBlockDelta: {
+                contentBlockIndex: 0,
+                delta: { text: "Response" },
+              },
+            };
+            yield {
+              metadata: {
+                usage: {
+                  inputTokens: 10,
+                  outputTokens: 5,
+                  totalTokens: 15,
+                },
+              },
+            };
+          })(),
+        };
+      }
+      return {};
+    }
+  }
+  return {
+    BedrockRuntimeClient,
+    ConverseCommand,
+    ConverseStreamCommand,
+  };
+});
+
+import {
+  ConverseCommand,
+  ConverseStreamCommand,
+} from "@aws-sdk/client-bedrock-runtime";
+
+describe("ChatBedrockConverse invocationParams", () => {
+  const baseConstructorArgs = {
+    region: "us-east-1",
+    credentials: {
+      secretAccessKey: "test-secret",
+      accessKeyId: "test-key",
+    },
+    model: "anthropic.claude-3-sonnet-20240229-v1:0",
+  };
+
+  describe("inferenceConfig conditional logic", () => {
+    test("covers all inferenceConfig scenarios compactly", () => {
+      const cases: Array<{
+        name: string;
+        ctor?: Partial<ConstructorParameters<typeof ChatBedrockConverse>[0]>;
+        opts?: Parameters<ChatBedrockConverse["invocationParams"]>[0];
+        expectDefined: boolean;
+        expectValues?: Partial<{
+          maxTokens: number;
+          temperature: number;
+          topP: number;
+          stopSequences: string[];
+        }>;
+        expectUndefinedKeys?: Array<
+          "maxTokens" | "temperature" | "topP" | "stopSequences"
+        >;
+      }> = [
+        {
+          name: "undefined when no inference values are set",
+          expectDefined: false,
+        },
+        {
+          name: "includes only maxTokens when set",
+          ctor: { maxTokens: 100 },
+          expectDefined: true,
+          expectValues: { maxTokens: 100 },
+          expectUndefinedKeys: ["temperature", "topP", "stopSequences"],
+        },
+        {
+          name: "includes only temperature when set",
+          ctor: { temperature: 0.7 },
+          expectDefined: true,
+          expectValues: { temperature: 0.7 },
+          expectUndefinedKeys: ["maxTokens", "topP", "stopSequences"],
+        },
+        {
+          name: "includes only topP when set",
+          ctor: { topP: 0.9 },
+          expectDefined: true,
+          expectValues: { topP: 0.9 },
+          expectUndefinedKeys: ["maxTokens", "temperature", "stopSequences"],
+        },
+        {
+          name: "includes stopSequences when provided",
+          opts: { stop: ["END", "STOP"] },
+          expectDefined: true,
+          expectValues: { stopSequences: ["END", "STOP"] },
+          expectUndefinedKeys: ["maxTokens", "temperature", "topP"],
+        },
+        {
+          name: "includes all values when all are set",
+          ctor: { maxTokens: 200, temperature: 0.5, topP: 0.95 },
+          opts: { stop: ["END"] },
+          expectDefined: true,
+          expectValues: {
+            maxTokens: 200,
+            temperature: 0.5,
+            topP: 0.95,
+            stopSequences: ["END"],
+          },
+        },
+        {
+          name: "undefined when stop sequences is empty array",
+          opts: { stop: [] },
+          expectDefined: false,
+        },
+      ];
+
+      for (const c of cases) {
+        const model = new ChatBedrockConverse({
+          ...baseConstructorArgs,
+          ...(c.ctor ?? {}),
+        });
+        const params = model.invocationParams(c.opts);
+        if (!c.expectDefined) {
+          expect(params.inferenceConfig).toBeUndefined();
+        } else {
+          expect(params.inferenceConfig).toBeDefined();
+          if (c.expectValues?.maxTokens !== undefined) {
+            expect(params.inferenceConfig?.maxTokens).toBe(
+              c.expectValues.maxTokens
+            );
+          }
+          if (c.expectValues?.temperature !== undefined) {
+            expect(params.inferenceConfig?.temperature).toBe(
+              c.expectValues.temperature
+            );
+          }
+          if (c.expectValues?.topP !== undefined) {
+            expect(params.inferenceConfig?.topP).toBe(c.expectValues.topP);
+          }
+          if (c.expectValues?.stopSequences !== undefined) {
+            expect(params.inferenceConfig?.stopSequences).toEqual(
+              c.expectValues.stopSequences
+            );
+          }
+          const ic = params.inferenceConfig as Record<
+            "maxTokens" | "temperature" | "topP" | "stopSequences",
+            unknown
+          >;
+          for (const k of c.expectUndefinedKeys ?? []) {
+            expect(ic?.[k]).toBeUndefined();
+          }
+        }
+      }
+    });
+  });
+
+  describe("system parameter conditional logic", () => {
+    test.each([
+      {
+        name: "no system messages",
+        messages: [new HumanMessage("Hello")],
+        expectedSystem: { present: false, length: 0, texts: [] as string[] },
+      },
+      {
+        name: "one system message",
+        messages: [
+          new SystemMessage("You are a helpful assistant."),
+          new HumanMessage("Hello"),
+        ],
+        expectedSystem: {
+          present: true,
+          length: 1,
+          texts: ["You are a helpful assistant."],
+        },
+      },
+      {
+        name: "multiple system messages",
+        messages: [
+          new SystemMessage("You are a helpful assistant."),
+          new SystemMessage("Be concise in your responses."),
+          new HumanMessage("Hello"),
+        ],
+        expectedSystem: {
+          present: true,
+          length: 2,
+          texts: [
+            "You are a helpful assistant.",
+            "Be concise in your responses.",
+          ],
+        },
+      },
+    ])(
+      "invoke should handle system parameter: $name",
+      async ({ messages, expectedSystem }) => {
+        const model = new ChatBedrockConverse(baseConstructorArgs);
+        await model.invoke(messages);
+        const input = Reflect.get(
+          ConverseCommand,
+          "lastInput"
+        ) as ConverseCommandInput;
+        if (expectedSystem.present) {
+          expect(input).toHaveProperty("system");
+          const system = input.system as NonNullable<typeof input.system>;
+          expect(system).toHaveLength(expectedSystem.length);
+          expectedSystem.texts.forEach((t, i) => {
+            expect(system[i]).toHaveProperty("text", t);
+          });
+        } else {
+          expect(input).not.toHaveProperty("system");
+        }
+      }
+    );
+  });
+
+  describe("stream method system parameter logic", () => {
+    test.each([
+      {
+        name: "no system messages",
+        messages: [new HumanMessage("Hello")],
+        expectedPresent: false,
+        expectedLength: 0,
+        expectedTexts: [] as string[],
+      },
+      {
+        name: "one system message",
+        messages: [
+          new SystemMessage("You are a helpful assistant."),
+          new HumanMessage("Hello"),
+        ],
+        expectedPresent: true,
+        expectedLength: 1,
+        expectedTexts: ["You are a helpful assistant."],
+      },
+    ])(
+      "stream should handle system parameter: $name",
+      async ({ messages, expectedPresent, expectedLength, expectedTexts }) => {
+        const model = new ChatBedrockConverse(baseConstructorArgs);
+        const stream = await model.stream(messages);
+        const chunks = [];
+        for await (const chunk of stream) {
+          chunks.push(chunk);
+        }
+        expect(chunks.length).toBeGreaterThan(0);
+        const input = Reflect.get(
+          ConverseStreamCommand,
+          "lastInput"
+        ) as ConverseStreamCommandInput;
+        if (expectedPresent) {
+          expect(input).toHaveProperty("system");
+          const system = input.system as NonNullable<typeof input.system>;
+          expect(system).toHaveLength(expectedLength);
+          expectedTexts.forEach((t: string, i: number) => {
+            expect(system[i]).toHaveProperty("text", t);
+          });
+        } else {
+          expect(input).not.toHaveProperty("system");
+        }
+      }
+    );
+  });
+});