Refactor API methods to use AsyncGenerator for SSE.

Updated `write_report` and `get_research_sources` to stream results via server-sent events (SSE) using `AsyncGenerator`. This allows incremental data delivery and better error reporting, improving client-server communication.

src/phoenix_technologies/gpt_researcher/server.py

@@ -240,7 +240,7 @@ async def quick_search(query: str) -> AsyncGenerator[str, None]:
 
 
 @mcp.tool()
-async def write_report(research_id: str, custom_prompt: Optional[str] = None) -> Dict[str, Any]:
+async def write_report(research_id: str, custom_prompt: Optional[str] = None) -> AsyncGenerator[str, None]:
     """
     Generate a report based on previously conducted research.
 
@@ -253,7 +253,7 @@ async def write_report(research_id: str, custom_prompt: Optional[str] = None) ->
     """
     success, researcher, error = get_researcher_by_id(mcp.researchers, research_id)
     if not success:
-        return error
+        yield format_sse_event("message", error)
 
     logger.info(f"Generating report for research ID: {research_id}")
 
@@ -265,17 +265,29 @@ async def write_report(research_id: str, custom_prompt: Optional[str] = None) ->
         sources = researcher.get_research_sources()
         costs = researcher.get_costs()
 
-        return create_success_response({
+        final_data_payload = {
             "report": report,
             "source_count": len(sources),
             "costs": costs
-        })
+        }
+
+        # Sende das finale Ergebnis als 'tool_result' Event
+        yield format_sse_event("message", final_data_payload)
+        logger.info(f"Sent final research result for ID: {research_id}")
     except Exception as e:
-        return handle_exception(e, "Report generation")
+        logger.error(f"Error during deep_research for query: {e}", exc_info=True)
+        # Sende ein Fehler-Event an den Client
+        error_payload = {
+            "research_id": research_id,
+            "status": "Error occurred",
+            "error_message": str(e),
+            "error_details": "Check server logs for more information."
+        }
+        yield format_sse_event("message", error_payload)
 
 
 @mcp.tool()
-async def get_research_sources(research_id: str) -> Dict[str, Any]:
+async def get_research_sources(research_id: str) -> AsyncGenerator[str, None]:
     """
     Get the sources used in the research.
 
@@ -287,15 +299,19 @@ async def get_research_sources(research_id: str) -> Dict[str, Any]:
     """
     success, researcher, error = get_researcher_by_id(mcp.researchers, research_id)
     if not success:
-        return error
+        yield format_sse_event("message", error)
 
     sources = researcher.get_research_sources()
     source_urls = researcher.get_source_urls()
 
-    return create_success_response({
+    final_data_payload = {
         "sources": format_sources_for_response(sources),
         "source_urls": source_urls
-    })
+    }
+
+    # Sende das finale Ergebnis als 'tool_result' Event
+    yield format_sse_event("message", final_data_payload)
+    logger.info(f"Sent final research result for ID: {research_id}")
 
 
 @mcp.tool()