fix(sdk): harden AG-UI dispatch, add exception hierarchy, fix docstrings

Address code review findings:
- Wrap AG-UI tool call dispatch in try/except with compensating
  TOOL_CALL_END to prevent clients hanging on partial emission
- Reject non-dict/non-str args at the dispatch layer (lists, ints, None)
- Guard against None event value before calling .get()
- Fix docstring examples that reuse variable names (won't compile)
- Introduce CopilotKitError base class; all exceptions now inherit from
  it; CopilotKitMisuseError inherits from both CopilotKitError and
  ValueError
- Add missing validation tests for name and args across LangGraph and
  CrewAI Python variants, plus AG-UI dispatch edge cases

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mxmzb

packages/sdk-js/src/langgraph/utils.ts

@@ -301,10 +301,10 @@ export async function copilotkitEmitMessage(
  * ```typescript
  * import { copilotkitEmitToolCall } from "@copilotkit/sdk-js";
  *
- * const toolCallId = await copilotkitEmitToolCall(config, "SearchTool", { steps: 10 });
+ * const autoId = await copilotkitEmitToolCall(config, "SearchTool", { steps: 10 });
  *
  * // With a custom ID for correlation/idempotency:
- * const toolCallId = await copilotkitEmitToolCall(config, "SearchTool", { steps: 10 }, { toolCallId: "my-custom-id" });
+ * const customId = await copilotkitEmitToolCall(config, "SearchTool", { steps: 10 }, { toolCallId: "my-custom-id" });
  * ```
  */
 export async function copilotkitEmitToolCall(

sdk-python/copilotkit/crewai/crewai_sdk.py

@@ -236,10 +236,10 @@ async def copilotkit_emit_tool_call(
     ```python
     from copilotkit.crewai import copilotkit_emit_tool_call
 
-    tool_call_id = await copilotkit_emit_tool_call(name="SearchTool", args={"steps": 10})
+    auto_id = await copilotkit_emit_tool_call(name="SearchTool", args={"steps": 10})
 
     # With a custom ID for correlation/idempotency:
-    tool_call_id = await copilotkit_emit_tool_call(name="SearchTool", args={"steps": 10}, tool_call_id="my-custom-id")
+    custom_id = await copilotkit_emit_tool_call(name="SearchTool", args={"steps": 10}, tool_call_id="my-custom-id")
     ```
 
     Parameters

sdk-python/copilotkit/exc.py

@@ -1,23 +1,32 @@
 """Exceptions for CopilotKit."""
 
 
-class ActionNotFoundException(Exception):
+class CopilotKitError(Exception):
+    """Base exception for all CopilotKit errors.
+
+    Catch this to handle any CopilotKit-specific exception.
+    """
+
+    pass
+
+
+class ActionNotFoundException(CopilotKitError):
     """Exception raised when an action or agent is not found."""
 
     def __init__(self, name: str):
         self.name = name
         super().__init__(f"Action '{name}' not found.")
 
 
-class AgentNotFoundException(Exception):
+class AgentNotFoundException(CopilotKitError):
     """Exception raised when an agent is not found."""
 
     def __init__(self, name: str):
         self.name = name
         super().__init__(f"Agent '{name}' not found.")
 
 
-class ActionExecutionException(Exception):
+class ActionExecutionException(CopilotKitError):
     """Exception raised when an action fails to execute."""
 
     def __init__(self, name: str, error: Exception):
@@ -26,7 +35,7 @@ def __init__(self, name: str, error: Exception):
         super().__init__(f"Action '{name}' failed to execute: {error}")
 
 
-class AgentExecutionException(Exception):
+class AgentExecutionException(CopilotKitError):
     """Exception raised when an agent fails to execute."""
 
     def __init__(self, name: str, error: Exception):
@@ -35,10 +44,11 @@ def __init__(self, name: str, error: Exception):
         super().__init__(f"Agent '{name}' failed to execute: {error}")
 
 
-class CopilotKitMisuseError(ValueError):
+class CopilotKitMisuseError(CopilotKitError, ValueError):
     """Exception raised when CopilotKit detects incorrect usage of its APIs.
 
-    Subclasses ValueError for backward compatibility with existing handlers.
+    Inherits from both CopilotKitError (for ``except CopilotKitError``) and
+    ValueError (for backward compatibility with ``except ValueError`` handlers).
     """
 
     pass

sdk-python/copilotkit/langgraph.py

@@ -387,10 +387,10 @@ async def copilotkit_emit_tool_call(
     ```python
     from copilotkit.langgraph import copilotkit_emit_tool_call
 
-    tool_call_id = await copilotkit_emit_tool_call(config, name="SearchTool", args={"steps": 10})
+    auto_id = await copilotkit_emit_tool_call(config, name="SearchTool", args={"steps": 10})
 
     # With a custom ID for correlation/idempotency:
-    tool_call_id = await copilotkit_emit_tool_call(config, name="SearchTool", args={"steps": 10}, tool_call_id="my-custom-id")
+    custom_id = await copilotkit_emit_tool_call(config, name="SearchTool", args={"steps": 10}, tool_call_id="my-custom-id")
     ```
 
     Parameters

sdk-python/copilotkit/langgraph_agui_agent.py

@@ -1,7 +1,10 @@
 import json
+import logging
 from typing import Dict, Any, List, Optional, Union, AsyncGenerator
 from enum import Enum
 from .exc import CopilotKitMisuseError
+
+logger = logging.getLogger(__name__)
 from ag_ui_langgraph import LangGraphAgent
 from ag_ui.core import (
     EventType,
@@ -106,6 +109,11 @@ def _dispatch_event(self, event) -> str:
 
             if custom_event.name == CustomEventNames.ManuallyEmitToolCall.value:
                 value = custom_event.value
+                if not isinstance(value, dict):
+                    raise CopilotKitMisuseError(
+                        f"ManuallyEmitToolCall event 'value' must be a dict, got {type(value).__name__}"
+                    )
+
                 tool_call_id = value.get("id")
                 tool_call_name = value.get("name")
                 tool_call_args = value.get("args")
@@ -118,9 +126,10 @@ def _dispatch_event(self, event) -> str:
                     raise CopilotKitMisuseError(
                         f"ManuallyEmitToolCall event missing valid 'name': got {type(tool_call_name).__name__}"
                     )
-                if tool_call_args is None:
+                if not isinstance(tool_call_args, (dict, str)):
                     raise CopilotKitMisuseError(
-                        "ManuallyEmitToolCall event missing 'args'"
+                        f"ManuallyEmitToolCall 'args' must be a dict or pre-serialized JSON string, "
+                        f"got {type(tool_call_args).__name__} for tool_call_id={tool_call_id}"
                     )
 
                 try:
@@ -129,35 +138,54 @@ def _dispatch_event(self, event) -> str:
                         if isinstance(tool_call_args, str)
                         else json.dumps(tool_call_args)
                     )
-                except (TypeError, ValueError) as e:
+                except Exception as e:
                     raise CopilotKitMisuseError(
                         f"ManuallyEmitToolCall 'args' is not JSON-serializable for tool_call_id={tool_call_id}: {e}"
                     ) from e
 
-                super()._dispatch_event(
-                    ToolCallStartEvent(
-                        type=EventType.TOOL_CALL_START,
-                        tool_call_id=tool_call_id,
-                        tool_call_name=tool_call_name,
-                        parent_message_id=tool_call_id,
-                        raw_event=event,
+                dispatched_start = False
+                try:
+                    super()._dispatch_event(
+                        ToolCallStartEvent(
+                            type=EventType.TOOL_CALL_START,
+                            tool_call_id=tool_call_id,
+                            tool_call_name=tool_call_name,
+                            parent_message_id=tool_call_id,
+                            raw_event=event,
+                        )
                     )
-                )
-                super()._dispatch_event(
-                    ToolCallArgsEvent(
-                        type=EventType.TOOL_CALL_ARGS,
-                        tool_call_id=tool_call_id,
-                        delta=delta,
-                        raw_event=event,
+                    dispatched_start = True
+                    super()._dispatch_event(
+                        ToolCallArgsEvent(
+                            type=EventType.TOOL_CALL_ARGS,
+                            tool_call_id=tool_call_id,
+                            delta=delta,
+                            raw_event=event,
+                        )
                     )
-                )
-                super()._dispatch_event(
-                    ToolCallEndEvent(
-                        type=EventType.TOOL_CALL_END,
-                        tool_call_id=tool_call_id,
-                        raw_event=event,
+                    super()._dispatch_event(
+                        ToolCallEndEvent(
+                            type=EventType.TOOL_CALL_END,
+                            tool_call_id=tool_call_id,
+                            raw_event=event,
+                        )
                     )
-                )
+                except Exception:
+                    if dispatched_start:
+                        try:
+                            super()._dispatch_event(
+                                ToolCallEndEvent(
+                                    type=EventType.TOOL_CALL_END,
+                                    tool_call_id=tool_call_id,
+                                    raw_event=event,
+                                )
+                            )
+                        except Exception as close_err:
+                            logger.error(
+                                "Failed to emit compensating TOOL_CALL_END for %s: %s",
+                                tool_call_id, close_err,
+                            )
+                    raise
                 return super()._dispatch_event(event)
 
             if custom_event.name == CustomEventNames.ManuallyEmitState.value:

sdk-python/copilotkit/sdk.py

@@ -10,6 +10,8 @@
 from .action import Action, ActionDict, ActionResultDict
 from .types import Message, MetaEvent
 from .exc import (
+    CopilotKitError,
+    CopilotKitMisuseError,
     ActionNotFoundException,
     AgentNotFoundException,
     ActionExecutionException,

sdk-python/tests/test_emit_tool_call_optional_id.py

@@ -4,6 +4,8 @@
   1. LangGraph variant: default UUID generation, custom ID passthrough, return value
   2. CrewAI variant: default UUID generation, custom ID passthrough, return value
   3. AG-UI agent dispatch: custom ID propagates to all three TOOL_CALL events
+  4. AG-UI dispatch validation: defensive CopilotKitMisuseError paths for
+     missing/invalid id, name, args, non-serializable args, and non-dict value
 """
 
 import json
@@ -163,6 +165,43 @@ async def test_whitespace_only_id_raises(self):
                     config, name="Tool", args={}, tool_call_id="   "
                 )
 
+    @pytest.mark.asyncio
+    async def test_whitespace_only_name_raises(self):
+        """Passing a whitespace-only name should raise CopilotKitMisuseError."""
+        with patch(
+            "copilotkit.langgraph.adispatch_custom_event", new_callable=AsyncMock
+        ):
+            from copilotkit.langgraph import copilotkit_emit_tool_call
+
+            config = {"metadata": {}}
+            with pytest.raises(CopilotKitMisuseError, match="non-empty string"):
+                await copilotkit_emit_tool_call(config, name="   ", args={})
+
+    @pytest.mark.asyncio
+    async def test_empty_name_raises(self):
+        """Passing an empty name should raise CopilotKitMisuseError."""
+        with patch(
+            "copilotkit.langgraph.adispatch_custom_event", new_callable=AsyncMock
+        ):
+            from copilotkit.langgraph import copilotkit_emit_tool_call
+
+            config = {"metadata": {}}
+            with pytest.raises(CopilotKitMisuseError, match="non-empty string"):
+                await copilotkit_emit_tool_call(config, name="", args={})
+
+    @pytest.mark.asyncio
+    async def test_non_dict_args_raises(self):
+        """Passing non-dict args should raise CopilotKitMisuseError."""
+        with patch(
+            "copilotkit.langgraph.adispatch_custom_event", new_callable=AsyncMock
+        ):
+            from copilotkit.langgraph import copilotkit_emit_tool_call
+
+            config = {"metadata": {}}
+            for bad_args in [None, [1, 2], "raw", 42]:
+                with pytest.raises(CopilotKitMisuseError, match="must be a dict"):
+                    await copilotkit_emit_tool_call(config, name="Tool", args=bad_args)
+
 
 # ---- CrewAI variant tests ----
 
@@ -254,6 +293,39 @@ async def test_whitespace_only_id_raises(self):
                     name="Tool", args={}, tool_call_id="   "
                 )
 
+    @pytest.mark.asyncio
+    async def test_none_id_generates_uuid(self):
+        """Explicitly passing tool_call_id=None should behave the same as omitting it."""
+        with patch(
+            "copilotkit.crewai.crewai_sdk.queue_put", new_callable=AsyncMock
+        ):
+            from copilotkit.crewai.crewai_sdk import copilotkit_emit_tool_call
+
+            result = await copilotkit_emit_tool_call(
+                name="Tool", args={}, tool_call_id=None
+            )
+            assert isinstance(result, str)
+            uuid.UUID(result)
+
+    @pytest.mark.asyncio
+    async def test_whitespace_only_name_raises(self):
+        """Passing a whitespace-only name should raise CopilotKitMisuseError."""
+        with patch("copilotkit.crewai.crewai_sdk.queue_put", new_callable=AsyncMock):
+            from copilotkit.crewai.crewai_sdk import copilotkit_emit_tool_call
+
+            with pytest.raises(CopilotKitMisuseError, match="non-empty string"):
+                await copilotkit_emit_tool_call(name="   ", args={})
+
+    @pytest.mark.asyncio
+    async def test_non_dict_args_raises(self):
+        """Passing non-dict args should raise CopilotKitMisuseError."""
+        with patch("copilotkit.crewai.crewai_sdk.queue_put", new_callable=AsyncMock):
+            from copilotkit.crewai.crewai_sdk import copilotkit_emit_tool_call
+
+            for bad_args in [None, [1, 2], "raw", 42]:
+                with pytest.raises(CopilotKitMisuseError, match="must be a dict"):
+                    await copilotkit_emit_tool_call(name="Tool", args=bad_args)
+
 
 # ---- AG-UI dispatch: custom ID propagates through all events ----
 
@@ -426,15 +498,45 @@ def test_missing_args_raises(self, agent):
             name=CustomEventNames.ManuallyEmitToolCall.value,
             value={"id": "valid-id", "name": "Tool"},
         )
-        with pytest.raises(CopilotKitMisuseError, match="missing 'args'"):
+        with pytest.raises(CopilotKitMisuseError, match="must be a dict or pre-serialized"):
             agent._dispatch_event(event)
 
     def test_non_serializable_args_raises(self, agent):
-        """Event with non-JSON-serializable args should raise CopilotKitMisuseError."""
+        """Event with non-JSON-serializable args (set) should raise CopilotKitMisuseError."""
         event = CustomEvent(
             type=EventType.CUSTOM,
             name=CustomEventNames.ManuallyEmitToolCall.value,
             value={"id": "valid-id", "name": "Tool", "args": {1, 2, 3}},
         )
-        with pytest.raises(CopilotKitMisuseError, match="not JSON-serializable"):
+        with pytest.raises(CopilotKitMisuseError, match="must be a dict or pre-serialized"):
+            agent._dispatch_event(event)
+
+    def test_non_dict_value_raises(self, agent):
+        """Event with non-dict value should raise CopilotKitMisuseError."""
+        event = CustomEvent(
+            type=EventType.CUSTOM,
+            name=CustomEventNames.ManuallyEmitToolCall.value,
+            value=None,
+        )
+        with pytest.raises(CopilotKitMisuseError, match="must be a dict"):
+            agent._dispatch_event(event)
+
+    def test_list_args_raises(self, agent):
+        """Event with list args should raise CopilotKitMisuseError."""
+        event = CustomEvent(
+            type=EventType.CUSTOM,
+            name=CustomEventNames.ManuallyEmitToolCall.value,
+            value={"id": "valid-id", "name": "Tool", "args": [1, 2, 3]},
+        )
+        with pytest.raises(CopilotKitMisuseError, match="must be a dict or pre-serialized"):
+            agent._dispatch_event(event)
+
+    def test_int_args_raises(self, agent):
+        """Event with int args should raise CopilotKitMisuseError."""
+        event = CustomEvent(
+            type=EventType.CUSTOM,
+            name=CustomEventNames.ManuallyEmitToolCall.value,
+            value={"id": "valid-id", "name": "Tool", "args": 42},
+        )
+        with pytest.raises(CopilotKitMisuseError, match="must be a dict or pre-serialized"):
             agent._dispatch_event(event)