A crowd you can find, and a phone 65px too narrow

Two reports against 1.6.0 and 1.7.0, both correct.

The crowd worked end to end and was, in practice, not there: the picker was
behind the ⋯ menu of a chat that already existed, and the switch was a card on
the Agents page, which made it read as an agent-chat feature. The picker is now
a button in the composer toolbar on both screens that include it, and on the
new-chat screen the choice rides along with the first message, so a chat can
start as a crowd instead of having to be converted into one. The instance
switch has its own page.

The width bug was the suggestion cards, exactly as reported. `.suggestions`
rendered 455px inside a 366px column, and the tree's standing rule applied on
its own made it worse -- 428px to 455px. A grid item carries `min-width: auto`,
which is a min-content floor, and a floor beats `width: 100%`; the floor is
measured while the percentage is indefinite, so `min(100%, …)` alone sends the
track to a card's max-content. Both halves now go on all four auto-fit grids,
and a test refuses either alone.

It survived four releases of narrow-width checking because the harness never
rendered that screen: `TestClient(app)` runs no lifespan outside a `with` block,
so the startup-seeded cards were missing from every shot ever taken of it. And
its overflow check skipped anything inside a scroller -- right for a table in
its own scroller, blind to the scroller itself, which `overflow-y: auto` makes
scroll sideways too. Both fixed; it now names the box and the child to blame.

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

src/lembas/web/static/css/chat.css

@@ -266,7 +266,27 @@
 */
 .suggestions {
   display: grid;
-  grid-template-columns: repeat(auto-fit, minmax(13rem, 1fr));
+  /* 🚨 `min-width: 0` is what keeps this grid on the screen, and `width: 100%`
+     alone did not: it is a grid item of `.thread__intro`, so it carries
+     `min-width: auto`, which for a grid item means *a min-content floor* -- and
+     min-width beats width. Its min-content size is two cards side by side, so it
+     rendered 428px wide inside a 390px phone with `width: 100%` set and ignored.
+
+     That floor is also why writing the track as `minmax(min(100%, 13rem), 1fr)`
+     -- the tree's standing rule, and right -- made it *worse* on its own, 428px
+     to 455px: a percentage is indefinite while the floor is being measured, so
+     the track fell back to a card's max-content and raised the very number that
+     was overflowing. The two go together. With the floor removed, `width: 100%`
+     finally resolves against the 366px column, `min(100%, …)` hands the track
+     366px to clamp against, and `auto-fit` places one column.
+
+     It scrolled `.thread-scroll` rather than the page, which is why a pass
+     looking for a document that scrolls sideways never saw it: `overflow-y: auto`
+     makes the other axis scrollable too. Reported on a phone, found by asking
+     which *element* could scroll and then reading its computed `width` against
+     its parent's. */
+  min-width: 0;
+  grid-template-columns: repeat(auto-fit, minmax(min(100%, 13rem), 1fr));
   gap: var(--sp-3);
   width: 100%;
   max-width: 40rem;