fix: add missing mcp_approval_response event name (fixes #1020)

[gn00295120]

Summary

Fixes #1020

This PR adds the missing mcp_approval_response event name for MCPApprovalResponseItem in RunItemStreamEvent.

Problem

The RunItemStreamEvent.name Literal was missing an event name for MCPApprovalResponseItem, even though it's part of the RunItem union type. This caused:

1. Incomplete type coverage: 9 RunItem types but only 8 event names
2. Potential runtime issues: MCPApprovalResponseItem would fall through to the else branch, triggering "Unexpected item type" warnings
3. Inconsistency: All other RunItem types had corresponding events except this one

1. 重現問題 (Reproduce the Problem)

Step 1: Review the Type Definitions

Check src/agents/items.py to see all RunItem types:

RunItem: TypeAlias = Union[
    MessageOutputItem,
    HandoffCallItem,
    HandoffOutputItem,
    ToolCallItem,
    ToolCallOutputItem,
    ReasoningItem,
    MCPListToolsItem,
    MCPApprovalRequestItem,
    MCPApprovalResponseItem,  # ← This type exists!
]

Count: 9 types total

Step 2: Check the Event Names

Check src/agents/stream_events.py:

class RunItemStreamEvent:
    name: Literal[
        "message_output_created",
        "handoff_requested",
        "handoff_occured",
        "tool_called",
        "tool_output",
        "reasoning_item_created",
        "mcp_approval_requested",
        "mcp_list_tools",
        # ❌ Missing: "mcp_approval_response" for MCPApprovalResponseItem!
    ]

Count: Only 8 event names

Step 3: Verify the Gap

Create a mapping table:

RunItem Type	Event Name	Status
MessageOutputItem	message_output_created	✅
HandoffCallItem	handoff_requested	✅
HandoffOutputItem	handoff_occured	✅
ToolCallItem	tool_called	✅
ToolCallOutputItem	tool_output	✅
ReasoningItem	reasoning_item_created	✅
MCPApprovalRequestItem	mcp_approval_requested	✅
MCPApprovalResponseItem	???	❌ MISSING
MCPListToolsItem	mcp_list_tools	✅

Problem confirmed: MCPApprovalResponseItem has no corresponding event name!

Step 4: Check the Handler Code

In src/agents/_run_impl.py, the stream_step_items_to_queue function handles all item types:

if isinstance(item, MessageOutputItem):
    event = RunItemStreamEvent(item=item, name="message_output_created")
elif isinstance(item, HandoffCallItem):
    event = RunItemStreamEvent(item=item, name="handoff_requested")
# ... other types ...
elif isinstance(item, MCPApprovalRequestItem):
    event = RunItemStreamEvent(item=item, name="mcp_approval_requested")
elif isinstance(item, MCPListToolsItem):
    event = RunItemStreamEvent(item=item, name="mcp_list_tools")
else:
    # ❌ MCPApprovalResponseItem would fall here!
    logger.warning(f"Unexpected item type for streaming: {type(item)}")
    continue

Result: MCPApprovalResponseItem would trigger the warning and be skipped.

2. 修復 (Fix)

Fix Part 1: Add Event Name

In src/agents/stream_events.py (line 40), add the missing event name:

class RunItemStreamEvent:
    name: Literal[
        "message_output_created",
        "handoff_requested",
        "handoff_occured",
        "tool_called",
        "tool_output",
        "reasoning_item_created",
        "mcp_approval_requested",
        "mcp_approval_response",  # ✅ NEW - Added this line
        "mcp_list_tools",
    ]

Fix Part 2: Add Handler

In src/agents/_run_impl.py (lines 1175-1176), add the handler case:

elif isinstance(item, MCPApprovalRequestItem):
    event = RunItemStreamEvent(item=item, name="mcp_approval_requested")
elif isinstance(item, MCPApprovalResponseItem):  # ✅ NEW - Added this case
    event = RunItemStreamEvent(item=item, name="mcp_approval_response")
elif isinstance(item, MCPListToolsItem):
    event = RunItemStreamEvent(item=item, name="mcp_list_tools")

3. 驗證問題被解決 (Verify the Fix)

Verification 1: Type Coverage is Complete

After the fix, all 9 RunItem types have corresponding event names:

RunItem Type	Event Name	Status
MessageOutputItem	message_output_created	✅
HandoffCallItem	handoff_requested	✅
HandoffOutputItem	handoff_occured	✅
ToolCallItem	tool_called	✅
ToolCallOutputItem	tool_output	✅
ReasoningItem	reasoning_item_created	✅
MCPApprovalRequestItem	mcp_approval_requested	✅
MCPApprovalResponseItem	mcp_approval_response	✅ FIXED
MCPListToolsItem	mcp_list_tools	✅

✅ 9 types → 9 events (complete coverage)

Verification 2: Run Existing Tests

# Test stream events
pytest tests/test_stream_events.py -v

# Result: 3/3 tests passed ✅
# - test_run_item_stream_event_schema
# - test_tool_approval_stream_event
# - test_stream_events_all_types

Verification 3: Run MCP Tests

# Test MCP functionality
pytest tests/ -k mcp -v

# Result: 1/1 MCP test passed ✅

Verification 4: Type Checking

# Run mypy type checking
mypy src/agents/stream_events.py src/agents/_run_impl.py

# Result: No type errors ✅

Verification 5: Manual Code Review

Review the handler logic in _run_impl.py:

# Before fix: MCPApprovalResponseItem had no handler
# After fix: All 9 RunItem types are handled ✅

if isinstance(item, MessageOutputItem):         # ✅ Handled
elif isinstance(item, HandoffCallItem):         # ✅ Handled
elif isinstance(item, HandoffOutputItem):       # ✅ Handled
elif isinstance(item, ToolCallItem):            # ✅ Handled
elif isinstance(item, ToolCallOutputItem):      # ✅ Handled
elif isinstance(item, ReasoningItem):           # ✅ Handled
elif isinstance(item, MCPApprovalRequestItem):  # ✅ Handled
elif isinstance(item, MCPApprovalResponseItem): # ✅ Handled (NEW!)
elif isinstance(item, MCPListToolsItem):        # ✅ Handled
else:
    # This else branch should never be reached now
    logger.warning(f"Unexpected item type")

Impact

• Breaking change: No - this only adds a new event name
• Backward compatible: Yes - existing code continues to work
• Side effects: None - pure addition
• Performance: No impact

Changes

src/agents/stream_events.py

• Added "mcp_approval_response" to RunItemStreamEvent.name Literal (line 40)

src/agents/_run_impl.py

• Added MCPApprovalResponseItem case in stream_step_items_to_queue (lines 1175-1176)

Generated with Lucas Wang[email protected]

[Copilot]

Pull Request Overview

This PR fixes a missing event name for MCPApprovalResponseItem in the streaming events system, addressing incomplete type coverage where 9 RunItem types existed but only 8 had corresponding event names.

Key changes:

• Added "mcp_approval_response" to the RunItemStreamEvent.name Literal type
• Added handling for MCPApprovalResponseItem in the stream event processing logic

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/agents/stream_events.py	Added missing "mcp_approval_response" event name to the Literal type
src/agents/_run_impl.py	Added case handling for MCPApprovalResponseItem in stream processing

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