Make the settings card behave like the other plugin cards

It rendered as a flat, always-open block with no header. The framework's card
chrome is a disclosure: the tab renders every card into a <ul>, each card's root
is an <li>, its header is its own <button> that discloses the controls in place,
it starts collapsed, the header marks it when it holds unsaved edits, and a save
that lands folds it back up.

Three things were wrong and only one of them was cosmetic:

  * the root was a <div> inside the tab's <ul>, so the list and card styling
    never reached it
  * there was no header button, so no disclosure and no aria-expanded
  * nothing marked unsaved edits, and nothing collapsed after a save

`PluginCard` is not importable — it lives in that package's client bundle, and
the client purity gate forbids cross-plugin value imports — so the behaviour is
reproduced rather than borrowed, with inline styles for the same reason.

The collapse-on-save originally lived in an effect watching a `saving` flag, which
is how the shipped card does it because its form state comes from a controller.
This card awaits its own writes, so it already knows the save landed; collapsing
directly in the success path is simpler and is what the tests can actually reach.
A failed save still keeps the card open with its drafts.

Tests cover the disclosure itself: the root element, collapsed-by-default, the
header's aria-expanded and label, that staged edits survive collapsing, and that
a landed save folds the card up.

client/client.js

@@ -7,6 +7,14 @@
  * claims, so a served namespace with no card draws nothing at all, and a card
  * whose namespace is not served is never dispatched.
  *
+ * The chrome follows the framework's `PluginCard`: the root is an `<li>` (the
+ * tab renders every card into a `<ul>`), the header is its own `<button>` that
+ * discloses the controls in place, the card starts collapsed, it marks itself
+ * when it holds unsaved edits, and it collapses again after a successful save.
+ * Nothing about that is imported — `PluginCard` lives in that package's client
+ * bundle and the client purity gate forbids cross-plugin value imports — so the
+ * behaviour is reproduced here rather than borrowed.
+ *
  * Hand-written plain JavaScript inside the module-loader wrapper, with no build
  * step and no bundler. `dsh plugin add git+…` fetches sources rather than build
  * output, so a `prepare` script would make every user allowlist a build before
@@ -14,8 +22,8 @@
  * platform seed table; anything outside that table would have to be bundled
  * into this file or declared in `dsh.client.external`.
  *
- * Styling is inline on purpose. The client bundle purity gate forbids
- * cross-plugin value imports, so there is no stylesheet this file may reach.
+ * Styling is inline on purpose, for the same reason: there is no stylesheet this
+ * file may reach.
  */
 window.__ModuleLoader__.load({
   id: 'dsh-slopo',
@@ -28,6 +36,9 @@ window.__ModuleLoader__.load({
     const NS = 'dsh-slopo'
     const h = react.createElement
 
+    const TITLE = 'Slopo'
+    const DESCRIPTION = 'Embedding backend, index scope and the budget that stops a large embed.'
+
     /**
      * The settings this card edits.
      *
@@ -79,11 +90,43 @@ window.__ModuleLoader__.load({
       { key: 'timeoutMs', label: 'Foreground timeout (ms)', kind: 'number' },
     ]
 
+    const BORDER = '1px solid var(--dsh-border, #3a3a3a)'
+
     const S = {
-      card: { border: '1px solid var(--dsh-border, #3a3a3a)', borderRadius: '8px', padding: '16px', margin: '8px 0' },
-      head: { display: 'flex', alignItems: 'baseline', justifyContent: 'space-between', gap: '12px', marginBottom: '4px' },
-      title: { fontSize: '14px', fontWeight: 600 },
-      badge: { fontSize: '11px', opacity: 0.7 },
+      // The tab renders into a <ul>, so the root must be an <li> or the list
+      // styling never reaches it.
+      card: { listStyle: 'none', border: BORDER, borderRadius: '8px', margin: '8px 0', overflow: 'hidden' },
+      cardOpen: { background: 'var(--dsh-surface, rgba(255,255,255,0.02))' },
+      header: {
+        display: 'flex',
+        alignItems: 'center',
+        gap: '12px',
+        width: '100%',
+        padding: '12px 16px',
+        border: 'none',
+        background: 'transparent',
+        color: 'inherit',
+        textAlign: 'left',
+        cursor: 'pointer',
+        font: 'inherit',
+      },
+      headText: { display: 'flex', flexDirection: 'column', gap: '2px', flex: '1 1 auto', minWidth: 0 },
+      name: { fontSize: '14px', fontWeight: 600 },
+      description: { fontSize: '11px', opacity: 0.65, lineHeight: 1.45 },
+      pending: {
+        flex: '0 0 auto',
+        fontSize: '10px',
+        textTransform: 'uppercase',
+        letterSpacing: '0.04em',
+        padding: '2px 6px',
+        borderRadius: '4px',
+        border: BORDER,
+        opacity: 0.8,
+      },
+      chevron: { flex: '0 0 auto', fontSize: '10px', opacity: 0.7, transition: 'transform 120ms ease' },
+      chevronOpen: { transform: 'rotate(180deg)' },
+      body: { padding: '0 16px 16px 16px' },
+      readOnly: { fontSize: '11px', opacity: 0.75, marginTop: 0, marginBottom: '12px' },
       hint: { fontSize: '11px', opacity: 0.65, marginTop: '2px', lineHeight: 1.45 },
       row: { marginTop: '12px' },
       label: { display: 'block', fontSize: '12px', fontWeight: 500, marginBottom: '4px' },
@@ -93,7 +136,7 @@ window.__ModuleLoader__.load({
         padding: '6px 8px',
         fontSize: '12px',
         borderRadius: '6px',
-        border: '1px solid var(--dsh-border, #3a3a3a)',
+        border: BORDER,
         background: 'transparent',
         color: 'inherit',
       },
@@ -102,14 +145,13 @@ window.__ModuleLoader__.load({
         padding: '6px 12px',
         fontSize: '12px',
         borderRadius: '6px',
-        border: '1px solid var(--dsh-border, #3a3a3a)',
+        border: BORDER,
         background: 'transparent',
         color: 'inherit',
         cursor: 'pointer',
       },
       primary: { fontWeight: 600 },
       note: { fontSize: '11px', opacity: 0.75, marginLeft: 'auto' },
-      dirty: { fontSize: '11px', opacity: 0.8 },
     }
 
     /** The editable string form of one field's value. */
@@ -180,6 +222,8 @@ window.__ModuleLoader__.load({
       const [draft, setDraft] = react.useState(null)
       const [busy, setBusy] = react.useState(false)
       const [note, setNote] = react.useState('')
+      // Collapsed on mount, like every other card in the tab.
+      const [open, setOpen] = react.useState(false)
 
       react.useEffect(() => scope.subscribe(() => setSnapshot(scope.getSnapshot())), [scope])
 
@@ -196,6 +240,7 @@ window.__ModuleLoader__.load({
 
       const dirtyKeys = FIELDS.filter((field) => current[field.key] !== baseline[field.key]).map((field) => field.key)
       const overriddenKeys = user !== null && typeof user === 'object' ? Object.keys(user) : []
+      const writable = snapshot.writable === true
 
       const save = async () => {
         setBusy(true)
@@ -211,6 +256,9 @@ window.__ModuleLoader__.load({
           }
           setDraft(null)
           setNote('Saved.')
+          // A landed save folds the card back up. A failed or blocked one stays
+          // open with the drafts, which is the whole point of staging them.
+          setOpen(false)
         } catch (error) {
           setNote(`Save failed: ${error?.message ?? error}`)
         } finally {
@@ -233,49 +281,59 @@ window.__ModuleLoader__.load({
       }
 
       return h(
-        'div',
-        { style: S.card },
+        'li',
+        { style: open ? { ...S.card, ...S.cardOpen } : S.card },
         h(
-          'div',
-          { style: S.head },
-          h('div', { style: S.title }, 'Slopo'),
+          'button',
+          {
+            type: 'button',
+            style: S.header,
+            'aria-expanded': open,
+            'aria-label': `${open ? 'Collapse' : 'Expand'}: ${TITLE}`,
+            onClick: () => setOpen(!open),
+          },
           h(
-            'div',
-            { style: S.badge },
-            status === 'loading' ? 'loading…' : 'configuration',
-            snapshot.writable === true ? '' : ' · read-only',
+            'span',
+            { style: S.headText },
+            h('span', { style: S.name }, TITLE),
+            h('span', { style: S.description }, DESCRIPTION),
           ),
+          // Marked on the header, so unsaved edits are visible while collapsed.
+          dirtyKeys.length > 0 ? h('span', { style: S.pending }, 'unsaved') : null,
+          h('span', { style: open ? { ...S.chevron, ...S.chevronOpen } : S.chevron }, '▾'),
         ),
-        h(
-          'div',
-          { style: S.hint },
-          'Slopo runs as a separate process. Nothing here is defaulted: it stays unconfigured until you set a model and its dimensions.',
-        ),
-        ...FIELDS.map((field) =>
-          h(Field, {
-            key: field.key,
-            field,
-            value: current[field.key],
-            overridden: overriddenKeys.includes(field.key),
-            disabled: busy || snapshot.writable !== true,
-            onChange: (next) => setDraft({ ...current, [field.key]: next }),
-          }),
-        ),
-        h(
-          'div',
-          { style: S.actions },
-          h(
-            'button',
-            { type: 'button', style: { ...S.button, ...S.primary }, disabled: busy || dirtyKeys.length === 0, onClick: save },
-            dirtyKeys.length === 0 ? 'Save' : `Save ${dirtyKeys.length} change${dirtyKeys.length === 1 ? '' : 's'}`,
-          ),
-          h(
-            'button',
-            { type: 'button', style: S.button, disabled: busy || overriddenKeys.length === 0, onClick: reset },
-            `Reset ${overriddenKeys.length} override${overriddenKeys.length === 1 ? '' : 's'}`,
-          ),
-          note === '' ? null : h('span', { style: S.note }, note),
-        ),
+        open
+          ? h(
+              'div',
+              { style: S.body },
+              writable ? null : h('p', { style: S.readOnly, role: 'status' }, 'This namespace is read-only here.'),
+              ...FIELDS.map((field) =>
+                h(Field, {
+                  key: field.key,
+                  field,
+                  value: current[field.key],
+                  overridden: overriddenKeys.includes(field.key),
+                  disabled: busy || !writable,
+                  onChange: (next) => setDraft({ ...current, [field.key]: next }),
+                }),
+              ),
+              h(
+                'div',
+                { style: S.actions },
+                h(
+                  'button',
+                  { type: 'button', style: { ...S.button, ...S.primary }, disabled: busy || dirtyKeys.length === 0, onClick: save },
+                  dirtyKeys.length === 0 ? 'Save' : `Save ${dirtyKeys.length} change${dirtyKeys.length === 1 ? '' : 's'}`,
+                ),
+                h(
+                  'button',
+                  { type: 'button', style: S.button, disabled: busy || overriddenKeys.length === 0, onClick: reset },
+                  `Reset ${overriddenKeys.length} override${overriddenKeys.length === 1 ? '' : 's'}`,
+                ),
+                note === '' ? null : h('span', { style: S.note }, note),
+              ),
+            )
+          : null,
       )
     }