[FEATURE] Graceful shutdown signal for headless/long-running sessions

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When running Claude Code headless (e.g., orchestrating via claude -p or long-running automated sessions), I want a way to request a graceful shutdown.

Proposed Solution

Requested behavior:
Some way to signal Claude Code to shut down gracefully. Equivalent to hitting <esc> to interrupt the thought and saying something like "Finish what you're doing and wrap this up, we need to stop."

1. Finish or abort the current tool call
2. Fire SessionEnd hooks
3. Terminate all child processes it spawned (Bash tool shells, subagents)
4. Exit cleanly

Alternative Solutions

Current behavior:

• SIGTERM / SIGINT kills the Claude Code process but orphans all Bash tool child processes (they get reparented to PID 1)
• SIGKILL is worse — no hooks fire at all
• SessionEnd hooks only fire on interactive exits (/exit, Ctrl+D)

Priority

Medium - Would be very helpful

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_