[BUG] --include-hook-events flag not emitting hook lifecycle events to message stream

[raman-kumar8]

Problem

When using the Claude Agent SDK (Python v0.2.87) with include_hook_events=True,
hook callbacks execute correctly but hook_started and hook_response system messages
are not emitted to the message stream, despite the --include-hook-events CLI flag
being passed to Claude Code.

Expected Behavior

According to the Agent SDK documentation,
when include_hook_events=True is set, the CLI should emit hook lifecycle events
(hook_started and hook_response messages with type: "system" and subtype in
["hook_started", "hook_response"]) into the message stream as HookEventMessage objects.

Actual Behavior

• Hook callbacks ARE returning correct hookSpecificOutput format
• --include-hook-events CLI flag IS being passed to Claude Code
• BUT hook_started and hook_response system messages NEVER appear in the stream
• Only init and status system messages appear

Steps to Reproduce

1. Use Claude Agent SDK (Python) with include_hook_events=True
2. Register PreToolUse and PostToolUse hooks
3. Make a query that triggers tool use
4. Listen to message stream with client.receive_messages()
5. Observe that HookEventMessage objects never appear

Environment

• Claude Code CLI: 2.1.150
• Claude Agent SDK (Python): 0.2.87
• Output format: stream-json
• Mode: Streaming/bidirectional

Logs

Hook callbacks execute and print to console, confirming they're being called.
However, no hook_started or hook_response messages appear in the parsed message stream.

python api.py
INFO: Started server process [34419]
INFO: Waiting for application startup.
INFO: Application startup complete.
INFO: Uvicorn running on http://0.0.0.0:8000 (Press CTRL+C to quit)
INFO: 127.0.0.1:51645 - "GET /chat HTTP/1.1" 200 OK

---

PreToolUse Event:
{'session_id': 'a561c82a-f6d7-4c89-b6f3-f839625b5dd1', 'transcript_path': '/Users/raman/.claude/projects/-Users-raman-Developer-claude-agent-sdk-backend/a561c82a-f6d7-4c89-b6f3-f839625b5dd1.jsonl', 'cwd': '/Users/raman/Developer/claude-agent-sdk/backend', 'permission_mode': 'default', 'hook_event_name': 'PreToolUse', 'tool_name': 'Bash', 'tool_input': {'command': 'find . -type f ! -path "/node_modules/" ! -path "/venv/" | wc -l', 'description': 'Count files in current directory, excluding node_modules and venv'}, 'tool_use_id': 'toolu_019AASM8eM8emLZiY565mA7N'}

---

---

PostToolUse Event:
{'session_id': 'a561c82a-f6d7-4c89-b6f3-f839625b5dd1', 'transcript_path': '/Users/raman/.claude/projects/-Users-raman-Developer-claude-agent-sdk-backend/a561c82a-f6d7-4c89-b6f3-f839625b5dd1.jsonl', 'cwd': '/Users/raman/Developer/claude-agent-sdk/backend', 'permission_mode': 'default', 'hook_event_name': 'PostToolUse', 'tool_name': 'Bash', 'tool_input': {'command': 'find . -type f ! -path "/node_modules/" ! -path "/venv/" | wc -l', 'description': 'Count files in current directory, excluding node_modules and venv'}, 'tool_response': {'stdout': ' 3', 'stderr': '', 'interrupted': False, 'isImage': False, 'noOutputExpected': False}, 'tool_use_id': 'toolu_019AASM8eM8emLZiY565mA7N', 'duration_ms': 59}

---

api.py

SSE UI STREAMS LOGS
data: {"type": "system", "subtype": "init"}

data: {"type": "system", "subtype": "status"}

data: {"type": "thinking", "thinking": "The user wants to find the number of files in the current working directory, ignoring node_modules and venv folders.\n\nI should use the Bash tool to run a command that counts files while excluding those directories. A good approach would be to use find command with appropriate exclusion patterns.\n\nLet me run a command to count the files."}

data: {"type": "tool_use", "tool": "Bash", "input": {"command": "find . -type f ! -path "/node_modules/" ! -path "/venv/" | wc -l", "description": "Count files in current directory, excluding node_modules and venv"}}

data: {"type": "system", "subtype": "status"}

data: {"type": "thinking", "thinking": "The command found 3 files in the current working directory when excluding node_modules and venv directories."}

data: {"type": "text", "text": "There are 3 files in the current working directory (excluding node_modules and venv directories)."}

[rudra-sett]

+1 - seeing this as well. just upgraded to 0.2.87 and am not seeing this work correctly.