Typing /summary (optionally with a topic hint) produces a structured
summary as a normal assistant message — without compacting or mutating
session history. Reuses the existing "Start new session from this answer"
button for hand-off.
Prompts are customizable in Settings → Magic Prompts under a new Session
group. Autocomplete shows an 'openchamber' badge to distinguish our
commands from OpenCode-built-in ones.