live sessions default to agents only, and you ask by name for a commander

`?kind=` was opt-in, so a client that said nothing got everything — which is the
wrong default for the one caller that cannot cope. The phone swipes between live
chats one at a time, has no room for tabs and no way to skip a row, so a commander
in that list is a commander you are stuck on. Defaulting to `agent` means
forgetting the parameter can only ever under-report.

The two callers that want both now say `kind=all` explicitly, and that is a fair
price: they are few, they are on screens built to show both kinds, and they are
the ones positioned to notice when the answer is wrong. `counts` still describes
every live session whatever the filter, so a filtered caller renders both tab
numbers from one request rather than two.

Also corrects useLiveSessions' comment, which said `isCommander` was derived from
the cwd. It stopped being true when a commander gained the right to choose its own
working directory — it comes from the `command_hq_sessions` row, and the directory
answers nothing.

Unrelated but caught by docs:check on the way past: the registry gained a
nineteenth entry (minesweeper, execution) and CLAUDE.md still said eighteen, which
also left the generated platform skill two lines stale. Both corrected; the check
is green again. The minesweeper feature itself is half-landed and not mine —
`rfb.ts` fails typecheck and its registry test fails on a websocket that is not
served.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/chat-sessions-list.md

@@ -57,6 +57,25 @@ so the walk exists — this is a second consumer of it, not a new class of work.
 live count needs no new endpoint. Correlate `live.claudeSessionId === session.id`; a live row whose id is
 still null contributes to no directory (see above).
 
+**`/chat/live` returns only agents unless asked otherwise.** `?kind=` takes `agent` (the default),
+`commander`, or `all`; anything else is a 400 rather than a silent fallback, and the plural forms are
+accepted because the web client's own type is already `'agents' | 'commanders'`.
+
+The default is the point. Commanders run background work and the phone swipes between live chats one at a
+time, with no room for tabs and no way to skip a row — so a client that forgets the parameter must not be
+handed a deploy commander. Defaulting to `agent` means forgetting can only ever under-report. The two
+callers that genuinely want both say `kind=all`, which is a fair price: they are few, they are on screens
+built to show both, and they are the ones positioned to notice if the answer is wrong.
+
+`counts` describes **every** live session regardless of the filter, so a filtered caller still renders
+`Agents (n) / Commanders (n)` without a second request. That is what stops a server-side filter from
+costing more round trips than the client-side one it replaced.
+
+Which rows are commanders comes from `command_hq_sessions`, **not** from the working directory — a
+commander chooses its own cwd, so the directory answers nothing. `GET /chat/sessions` reports no
+`isCommander` at all, because it removes commanders entirely; a list that excludes them has nothing to say
+about which of its rows is one.
+
 ---
 
 ## Landmines