End-of-session ritual that turns sessions into institutional memory via Zengram. Detects repeatable workflows worth capturing as skills AND mistakes/corrections worth capturing as CLAUDE.md rules. Reflects honestly, stores to Zengram, updates local memory, spots workflow patterns, and proposes rule updates. Use when the user types /sessionend, says they're done, wrapping up, signing off, 'that's it for today', 'end session', 'let's wrap up', 'save and close', or any signal that the session is ending. Also triggers on 'session summary', 'what did we do', or 'capture this session'. This is the closing ritual — if a session is ending, start here.