fix: disable streaming by default in sync chat methods (fixes #1733)

src/praisonai-agents/praisonaiagents/agent/chat_mixin.py

@@ -507,7 +507,7 @@ def _process_stream_response(self, messages, temperature, start_time, formatted_
             emit_events=True
         )
 
-    def _chat_completion(self, messages, temperature=1.0, tools=None, stream=True, reasoning_steps=False, task_name=None, task_description=None, task_id=None, response_format=None, _retry_depth=0):
+    def _chat_completion(self, messages, temperature=1.0, tools=None, stream=None, reasoning_steps=False, task_name=None, task_description=None, task_id=None, response_format=None, _retry_depth=0):
         start_time = time.time()
 
         # --- Context compaction (opt-in via ExecutionConfig.context_compaction) ---
@@ -577,6 +577,39 @@ def _chat_completion(self, messages, temperature=1.0, tools=None, stream=True, r
         # Use the new _format_tools_for_completion helper method
         formatted_tools = self._format_tools_for_completion(tools)
 
+        # Smart fallback for streaming: try streaming first, fall back to non-streaming if unsupported
+        if stream is None:
+            # Auto-detect: prefer streaming for better UX, fallback if adapter doesn't support it
+            try:
+                # First attempt: try with streaming enabled for better user experience
+                stream_callback = self.stream_emitter.emit if hasattr(self, 'stream_emitter') else None
+                final_response = self._execute_unified_chat_completion(
+                    messages=messages,
+                    temperature=temperature,
+                    tools=formatted_tools,
+                    stream=True,  # Try streaming first
+                    reasoning_steps=reasoning_steps,
+                    task_name=task_name,
+                    task_description=task_description,
+                    task_id=task_id,
+                    response_format=response_format,
+                    stream_callback=stream_callback,
+                    emit_events=True
+                )
+                return final_response
+            except ValueError as e:
+                if "Streaming is not supported" in str(e):
+                    # Fallback: retry with non-streaming for sync adapters
+                    logging.debug(f"{self.name}: Streaming not supported by adapter, falling back to non-streaming")
+                    stream = False  # Set for the main execution below
+                else:
+                    raise  # Re-raise if it's a different ValueError
+            except Exception:
+                # For any other exception, fall back to non-streaming
+                logging.debug(f"{self.name}: Streaming attempt failed, falling back to non-streaming")
+                stream = False  # Set for the main execution below
+
+        # If stream was explicitly set or fallback occurred, use the specified/fallback value
         try:
             # NEW: Unified protocol dispatch path (Issue #1304, #1362)
             # UNIFIED: Single protocol-driven dispatch path (fixes DRY violation)
@@ -774,7 +807,7 @@ def _execute_unified_chat_completion(
         messages, 
         temperature=1.0, 
         tools=None, 
-        stream=True,
+        stream=None,
         reasoning_steps=False,
         task_name=None,
         task_description=None,
@@ -806,6 +839,47 @@ def _execute_unified_chat_completion(
             # Cache the dispatcher
             self._unified_dispatcher = dispatcher
 
+        # Smart fallback for streaming: try streaming first, fall back to non-streaming if unsupported
+        if stream is None:
+            # Auto-detect: prefer streaming for better UX, fallback if adapter doesn't support it
+            try:
+                # First attempt: try with streaming enabled for better user experience
+                if stream_callback is None and hasattr(self, 'stream_emitter'):
+                    stream_callback = getattr(self.stream_emitter, 'emit', None)
+                final_response = self._unified_dispatcher.chat_completion(
+                    messages=messages,
+                    tools=tools,
+                    tool_choice=getattr(self, 'tool_choice', None),
+                    temperature=temperature,
+                    max_tokens=getattr(self, 'max_tokens', None),
+                    stream=True,  # Try streaming first
+                    response_format=response_format,
+                    execute_tool_fn=getattr(self, 'execute_tool', None),
+                    console=self.console if (self.verbose or True) else None,  # Enable console for streaming
+                    display_fn=self._display_generating if self.verbose else None,
+                    stream_callback=stream_callback,
+                    emit_events=emit_events,
+                    verbose=self.verbose,
+                    max_iterations=10,
+                    reasoning_steps=reasoning_steps,
+                    task_name=task_name,
+                    task_description=task_description,
+                    task_id=task_id,
+                    agent_name=getattr(self, 'name', 'assistant')
+                )
+                return final_response
+            except ValueError as e:
+                if "Streaming is not supported" in str(e):
+                    # Fallback: retry with non-streaming for sync adapters
+                    logging.debug(f"Agent: Streaming not supported by adapter, falling back to non-streaming")
+                    stream = False  # Set for the main execution below
+                else:
+                    raise  # Re-raise if it's a different ValueError
+            except Exception:
+                # For any other exception, fall back to non-streaming
+                logging.debug(f"Agent: Streaming attempt failed, falling back to non-streaming")
+                stream = False  # Set for the main execution below
+
         # Execute unified dispatch with all necessary parameters
         # Includes all parameters from both legacy paths to ensure full compatibility
         try:
@@ -857,7 +931,7 @@ async def _execute_unified_achat_completion(
         messages, 
         temperature=1.0, 
         tools=None, 
-        stream=True,
+        stream=True,  # Async methods keep stream=True default (async adapters support streaming vs sync smart fallback)
         reasoning_steps=False,
         task_name=None,
         task_description=None,

src/praisonai-agents/tests/unit/agent/test_chat_sync_stream_defaults.py

@@ -0,0 +1,48 @@
+import ast
+from pathlib import Path
+
+
+def _chat_mixin_path() -> Path:
+    for candidate in Path(__file__).resolve().parents:
+        chat_mixin = candidate / "praisonaiagents" / "agent" / "chat_mixin.py"
+        if chat_mixin.exists():
+            return chat_mixin
+    raise FileNotFoundError("Could not locate praisonaiagents/agent/chat_mixin.py")
+
+
+def get_chat_mixin_stream_parameter_default(function_name: str):
+    chat_mixin = _chat_mixin_path()
+    tree = ast.parse(chat_mixin.read_text(encoding="utf-8"))
+
+    for node in tree.body:
+        if isinstance(node, ast.ClassDef) and node.name == "ChatMixin":
+            for item in node.body:
+                if isinstance(item, ast.FunctionDef) and item.name == function_name:
+                    args = item.args.args
+                    defaults = item.args.defaults
+                    first_default_index = len(args) - len(defaults)
+                    for idx, arg in enumerate(args):
+                        if arg.arg == "stream":
+                            default_idx = idx - first_default_index
+                            if default_idx < 0:
+                                raise AssertionError(
+                                    f"Function '{function_name}' has no default for stream"
+                                )
+                            default = defaults[default_idx]
+                            if isinstance(default, ast.Constant):
+                                return default.value
+                            raise AssertionError(
+                                f"Function '{function_name}' stream default is non-constant"
+                            )
+    raise AssertionError(f"Function '{function_name}' or stream parameter not found")
+
+
+def test_chat_completion_stream_default_is_none():
+    assert get_chat_mixin_stream_parameter_default("_chat_completion") is None
+
+
+def test_execute_unified_chat_completion_stream_default_is_none():
+    assert (
+        get_chat_mixin_stream_parameter_default("_execute_unified_chat_completion")
+        is None
+    )