feat: Enhance chat streaming and tool call processing (#498)

* feat: Enhance chat streaming and tool call processing

- Added support for MongoDB checkpointer in the chat streaming workflow.
- Introduced functions to process tool call chunks and sanitize arguments.
- Improved event message creation with additional metadata.
- Enhanced error handling for JSON serialization in event messages.
- Updated the frontend to convert escaped characters in tool call arguments.
- Refactored the workflow input preparation and initial message processing.
- Added new dependencies for MongoDB integration and tool argument sanitization.

* fix: Update MongoDB checkpointer configuration to use LANGGRAPH_CHECKPOINT_DB_URL

* feat: Add support for Postgres checkpointing and update README with database recommendations

* feat: Implement checkpoint saver functionality and update MongoDB connection handling

* refactor: Improve code formatting and readability in app.py and json_utils.py

* refactor: Clean up commented code and improve formatting in server.py

* refactor: Remove unused imports and improve code organization in app.py

* refactor: Improve code organization and remove unnecessary comments in app.py

* chore: use langgraph-checkpoint-postgres==2.0.21 to avoid the JSON convert issue in the latest version, implement chat stream persistant with Postgres

* feat: add MongoDB and PostgreSQL support for LangGraph checkpointing, enhance environment variable handling

* fix: update comments for clarity on Windows event loop policy

* chore: remove empty code changes in MongoDB and PostgreSQL checkpoint tests

* chore: clean up unused imports and code in checkpoint-related files

* chore: remove empty code changes in test_checkpoint.py

* chore: remove empty code changes in test_checkpoint.py

* chore: remove empty code changes in test_checkpoint.py

* test: update status code assertions in MCP endpoint tests to allow for 403 responses

* test: update MCP endpoint tests to assert specific status codes and enable MCP server configuration

* chore: remove unnecessary environment variables from unittest workflow

* fix: invert condition for MCP server configuration check to raise 403 when disabled

* chore: remove pymongo from test dependencies in uv.lock

* chore:  optimize the _get_agent_name method

* test: enhance ChatStreamManager tests for PostgreSQL and MongoDB initialization

* test: add persistence tests for ChatStreamManager with PostgreSQL and MongoDB

* test: add unit tests for ChatStreamManager initialization with PostgreSQL and MongoDB

* test: enhance persistence tests for ChatStreamManager with PostgreSQL and MongoDB to verify message aggregation

* test: add unit tests for ChatStreamManager with PostgreSQL and MongoDB

* test: add unit tests for ChatStreamManager initialization with PostgreSQL and MongoDB

* test: add unit tests for ChatStreamManager initialization with PostgreSQL and MongoDB

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

web/src/core/messages/merge-message.ts

@@ -49,7 +49,11 @@ function mergeTextMessage(message: Message, event: MessageChunkEvent) {
     message.reasoningContentChunks.push(event.data.reasoning_content);
   }
 }
-
+function convertToolChunkArgs(args: string) {
+  // Convert escaped characters in args
+  if (!args) return "";
+  return args.replace(/[/g, "[").replace(/]/g, "]").replace(/{/g, "{").replace(/}/g, "}");
+}
 function mergeToolCallMessage(
   message: Message,
   event: ToolCallsEvent | ToolCallChunksEvent,
@@ -70,14 +74,14 @@ function mergeToolCallMessage(
         (toolCall) => toolCall.id === chunk.id,
       );
       if (toolCall) {
-        toolCall.argsChunks = [chunk.args];
+        toolCall.argsChunks = [convertToolChunkArgs(chunk.args)];
       }
     } else {
       const streamingToolCall = message.toolCalls.find(
         (toolCall) => toolCall.argsChunks?.length,
       );
       if (streamingToolCall) {
-        streamingToolCall.argsChunks!.push(chunk.args);
+        streamingToolCall.argsChunks!.push(convertToolChunkArgs(chunk.args));
       }
     }
   }