Send save prompt to inner Claude before session shutdown

[dcellison]

Summary

When the inner Claude subprocess is about to be killed (idle eviction, /stop, restart), it has no opportunity to save what it learned during the session. Interactive Claude Code sessions do this automatically via auto-memory, but the inner Claude runs in stream-json mode where auto-memory does not function.

A "save prompt" sent before shutdown would give the inner Claude a chance to persist important context to MEMORY.md, replicating the auto-memory save behavior for the headless subprocess.

Proposed approach

Before killing the subprocess, send a final message like:

"Save anything worth remembering from this session to your memory file, then respond with DONE."

Wait for the response (with a short timeout), then proceed with the kill.

Considerations

• Requires sending a message to a subprocess that's about to be killed
• Need to wait for the save to complete before killing (short timeout)
• Must handle the case where the subprocess is unresponsive (timeout and kill anyway)
• The /stop path needs the kill to be fast - the save prompt adds latency
• Idle eviction is the most natural place for this (the subprocess is about to die anyway, no user waiting)
• Could be limited to idle eviction only, skipping /stop (which implies urgency)

Depends on

• Fix inner Claude memory path #147 (inner Claude needs the correct MEMORY.md path first)

Priority

Low. This is an enhancement for long-term memory building. The explicit memory system (CLAUDE.md + MEMORY.md + history) handles the core use case.

[dcellison]

Triage by Kai

Triage summary: Feature request to send a save-prompt to the inner Claude subprocess before shutdown (idle eviction or /stop) so it can persist session context to MEMORY.md, replicating auto-memory behavior for headless stream-json mode. Explicitly marked low priority and depends on #147.

Priority: low
Labels applied: enhancement
Related issues: #147