Currently both system subtypes fall through to the generic muted
note renderer (⚙ <subtype>), giving the operator no insight into
what is happening.
plugin_install:
Render status explicitly — "loading…" on started, "✓ done" on
completed — so a slow plugin boot is visible in the scrollback
instead of two identical cryptic rows.
commands_changed:
Render the count of available slash commands in the summary row
and expand to the full list in a collapsible details block. The
list is most useful right after a fresh plugin_install so the
operator can see exactly which /commands are now on offer.
Both handlers sit immediately before the generic catch-all in the
system-subtype dispatch in renderStream, preserving the existing
fall-through for other subtypes (context_window_exceeded etc.).
Closes#2183.