Typing /context in the composer opens a centered dialog with the current
composition (provider-anchored headline, stacked bar, legend) and the
last-10-turn trend chart — the same pushed contextTimeline projection the
tab renders, no RPC, no polling.
The command is the plugin's own '/' trigger source, fully client-side:
no host descriptor, no session log records, nothing model-visible. The
composer token is consumed only when the modal closes (deferred
slash/input-consume-token with span / bare-token guards, fail-soft if the
draft changed meanwhile). Esc, backdrop click, and the close button all
close it and restore composer focus.
Also extracts the provider-anchored headline derivation shared by the tab
and the modal (headline.ts).