support AWS bedrock agents with streaming (#4850)

* support AWS bedrock agents with streaming

* Add back error handlers from previous fix

server/utils/AiProviders/bedrock/index.js

@@ -146,10 +146,13 @@ class AWSBedrockLLM {
   }
 
   /**
-   * Indicates if the provider supports streaming responses.
-   * @returns {boolean} True.
+   * Some Bedrock models (Titan, Cohere) don't support streaming.
+   * Set AWS_BEDROCK_STREAMING_DISABLED to any value to disable streaming for those models.
+   * Since this can be any model even custom models we leave it to the user to disable streaming if needed.
+   * @returns {boolean} True if streaming is supported, false otherwise.
    */
   streamingEnabled() {
+    if (!!process.env.AWS_BEDROCK_STREAMING_DISABLED) return false;
     return "streamGetChatCompletion" in this;
   }
 

server/utils/agents/aibitat/providers/bedrock.js

@@ -34,8 +34,15 @@ class AWSBedrockProvider extends InheritMultiple([Provider, UnTooled]) {
     this.verbose = true;
   }
 
+  /**
+   * Some Bedrock models (Titan, Cohere) don't support streaming.
+   * Set AWS_BEDROCK_STREAMING_DISABLED to any value to disable streaming for those models.
+   * Since this can be any model even custom models we leave it to the user to disable streaming if needed.
+   * @returns {boolean} True if streaming is supported, false otherwise.
+   */
   get supportsAgentStreaming() {
-    return false;
+    if (!!process.env.AWS_BEDROCK_STREAMING_DISABLED) return false;
+    return true;
   }
 
   /**
@@ -90,6 +97,73 @@ class AWSBedrockProvider extends InheritMultiple([Provider, UnTooled]) {
     return response?.content;
   }
 
+  /**
+   * Create a streaming response from the Langchain Bedrock client and convert
+   * it to OpenAI-compatible format expected by UnTooled.
+   * @param {Object} options - The options object containing messages.
+   * @param {Array} options.messages - The messages to send to the LLM.
+   * @returns {AsyncGenerator} An async iterable yielding OpenAI-compatible chunks.
+   */
+  async #handleFunctionCallStream({ messages = [] }) {
+    const langchainMessages = this.#convertToLangchainPrototypes(messages);
+    const stream = await this.client.stream(langchainMessages);
+
+    // Wrap Langchain stream to OpenAI format expected by UnTooled
+    const self = this;
+    return {
+      async *[Symbol.asyncIterator]() {
+        try {
+          for await (const chunk of stream) {
+            // Langchain chunks have .content property directly
+            const content =
+              typeof chunk.content === "string" ? chunk.content : "";
+            if (content) {
+              yield {
+                choices: [
+                  {
+                    delta: {
+                      content: content,
+                    },
+                  },
+                ],
+              };
+            }
+          }
+        } catch (e) {
+          AWSBedrockLLM.errorToHumanReadable(e, {
+            method: "stream",
+            model: self.model,
+          });
+        }
+      },
+    };
+  }
+
+  /**
+   * Stream a chat completion from the Bedrock LLM with tool calling.
+   *
+   * @param {any[]} messages - The messages to send to the LLM.
+   * @param {any[]} functions - The functions to use in the LLM.
+   * @param {function} eventHandler - The event handler to use to report stream events.
+   * @returns {Promise<{ functionCall: any, textResponse: string }>} - The result of the chat completion.
+   */
+  async stream(messages, functions = [], eventHandler = null) {
+    return await UnTooled.prototype.stream
+      .call(
+        this,
+        messages,
+        functions,
+        this.#handleFunctionCallStream.bind(this),
+        eventHandler
+      )
+      .catch((e) => {
+        AWSBedrockLLM.errorToHumanReadable(e, {
+          method: "stream",
+          model: this.model,
+        });
+      });
+  }
+
   /**
    * Create a completion based on the received messages.
    *
@@ -98,54 +172,14 @@ class AWSBedrockProvider extends InheritMultiple([Provider, UnTooled]) {
    * @returns The completion.
    */
   async complete(messages, functions = []) {
-    try {
-      let completion;
-      if (functions.length > 0) {
-        const { toolCall, text } = await this.functionCall(
-          messages,
-          functions,
-          this.#handleFunctionCallChat.bind(this)
-        );
-
-        if (toolCall !== null) {
-          this.providerLog(`Valid tool call found - running ${toolCall.name}.`);
-          this.deduplicator.trackRun(toolCall.name, toolCall.arguments);
-          return {
-            result: null,
-            functionCall: {
-              name: toolCall.name,
-              arguments: toolCall.arguments,
-            },
-            cost: 0,
-          };
-        }
-        completion = { content: text };
-      }
-
-      if (!completion?.content) {
-        this.providerLog(
-          "Will assume chat completion without tool call inputs."
-        );
-        const response = await this.client.invoke(
-          this.#convertToLangchainPrototypes(this.cleanMsgs(messages))
-        );
-        completion = response;
-      }
-
-      // The UnTooled class inherited Deduplicator is mostly useful to prevent the agent
-      // from calling the exact same function over and over in a loop within a single chat exchange
-      // _but_ we should enable it to call previously used tools in a new chat interaction.
-      this.deduplicator.reset("runs");
-      return {
-        result: completion.content,
-        cost: 0,
-      };
-    } catch (error) {
-      AWSBedrockLLM.errorToHumanReadable(error, {
-        method: "complete",
-        model: this.model,
+    return await UnTooled.prototype.complete
+      .call(this, messages, functions, this.#handleFunctionCallChat.bind(this))
+      .catch((e) => {
+        AWSBedrockLLM.errorToHumanReadable(e, {
+          method: "complete",
+          model: this.model,
+        });
       });
-    }
   }
 
   /**

server/utils/helpers/updateENV.js

@@ -1251,6 +1251,9 @@ function dumpENV() {
 
     // Allow disabling of MCP tool cooldown
     "MCP_NO_COOLDOWN",
+
+    // Allow disabling of streaming for AWS Bedrock
+    "AWS_BEDROCK_STREAMING_DISABLED",
   ];
 
   // Simple sanitization of each value to prevent ENV injection via newline or quote escaping.