CLAUDE_CODE_EMIT_USER_PROMPT_SUBMIT_HOOK_EVENTS

Updated October 31, 2026 by Alex Sorokoletov

CLAUDE_CODE_EMIT_USER_PROMPT_SUBMIT_HOOK_EVENTS is a Claude Code environment variable: When set, enables emitting start and end hook events for user prompt submission; the value is read once and then cleared. Added in v2.1.311 and still present in v2.1.315. It is not in the official reference.

How to set it

For one session, export it in the shell that starts Claude Code:

export CLAUDE_CODE_EMIT_USER_PROMPT_SUBMIT_HOOK_EVENTS=<value>
claude

To apply it to every session, add it to the env object of a settings file:

// ~/.claude/settings.json
{
  "env": {
    "CLAUDE_CODE_EMIT_USER_PROMPT_SUBMIT_HOOK_EVENTS": "<value>"
  }
}

Related variables

• CLAUDE_CODE_APPEND_PROMPT_HEAD: Designates a prompt-head string that is validated for integrity before use and then cleared after a single read; an invalid value is ignored.
• CLAUDE_CODE_ATTACHMENTS_IN_USER_DATA: Off unless set.
• CLAUDE_CODE_CONFIG_WATCH_EVENTS: On Linux, when set, watches config files with filesystem events instead of interval polling; ignored on other platforms.
• CLAUDE_CODE_EMIT_STARTUP_TIMING: When set, emits startup timing phase metrics, which are also emitted in remote mode; otherwise they are not reported.
• CLAUDE_CODE_MESSAGES_PROMPT_CACHE_TTL: Set to 5m to force the messages prompt cache to a five-minute lifetime.
• CLAUDE_CODE_MORNING_BRIEF_PROMPT: Set a custom prompt for the morning brief; used when its trimmed length was within bounds, otherwise the default prompt applied.
• CLAUDE_CODE_PROMPT_CACHE_TTL: Sets the prompt cache TTL for the main conversation (interactive, -p, and SDK turns) to "5m" or "1h".
• CLAUDE_CODE_REMOVE_PROMPT_STRINGS: Takes a JSON array of strings that are stripped from the prompt before sending; falls back to the remove_prompt_strings client setting, and is ignored when it is not a valid list.

Frequently asked questions

All variables, searchable: Claude Code environment variables.