fix(fleet): equalize action card heights, swap order, replace native autocomplete (#1138)

Three visual adjustments to the Fleet Actions tab:

1. Drop the xl:grid-cols-3 breakpoint. The cards carry live previews and
   per-node estimate wells that compress badly at 3-up on a 1440 monitor.
   2-up is the new max. Pair with auto-rows-fr so every row equalizes to
   the tallest content height, and let <FleetActionCard> stretch into the
   cell via flex flex-col h-full plus a flex-1 body. Footer pins to the
   bottom; the shorter card's body grows whitespace below its content.

2. Reorder the JSX to Prune, Bulk, Stop. Prune sits top-left with its
   live "~ N GB reclaimable" estimate populated on first render. Stop,
   which reads "awaiting target" until the operator types, drops to
   row 2 below the fold.

3. Replace the native <datalist> on the Stop card with a custom
   LabelAutocomplete: free-form text input + a Sencho-styled popover
   (border-glass-border, bg-popover, backdrop-blur) that filters the
   known-label set as the operator types. Click a suggestion via
   mousedown + preventDefault so the input stays focused and the
   selection registers before any blur-driven close. Outside-click and
   Escape close the popover. Operator can still run against a label
   that was not in the autocomplete set; the server-side match-preview
   resolves it.

Also: whitespace-nowrap on the primary button so "Stop fleet" /
"Prune fleet" do not wrap in tight viewports.

frontend/src/components/fleet/FleetActions/FleetActionsTab.tsx

@@ -22,14 +22,17 @@ export function FleetActionsTab({ nodes }: Props) {
     return <EmptyState />;
   }
 
-  // Grid breakpoints per audit §18.7: 1 / 2 / 3 columns at 760 / 1280. The
-  // 4-column breakpoint is reserved for when a 4th card lands; v1 has three
-  // so it is intentionally omitted to avoid a hanging gap on wide displays.
+  // Grid: 1 col under lg, 2 cols at lg and above. auto-rows-fr distributes
+  // available height evenly across the auto-created rows, and each card uses
+  // `flex flex-col h-full` (in <FleetActionCard>) with a `flex-1` body so it
+  // fills its grid cell. Result: all three cards render at the same height,
+  // with shorter cards growing their body whitespace before the footer pins.
+  // Order: Prune top-left, Bulk top-right, Stop on row 2.
   return (
-    <div className="grid grid-cols-1 lg:grid-cols-2 xl:grid-cols-3 gap-[18px] items-start auto-rows-min">
-      <LabelFleetStopCard nodes={nodes} />
-      <BulkLabelAssignCard nodes={nodes} />
+    <div className="grid grid-cols-1 lg:grid-cols-2 gap-[18px] auto-rows-fr">
       <FleetPruneCard nodes={nodes} />
+      <BulkLabelAssignCard nodes={nodes} />
+      <LabelFleetStopCard nodes={nodes} />
     </div>
   );
 }

frontend/src/components/fleet/FleetActions/cards/LabelFleetStopCard.tsx

@@ -201,18 +201,13 @@ export function LabelFleetStopCard({ nodes }: Props) {
           title="Label · target"
           meta={`auto-suggested · ${knownLabelNames.length} known`}
         >
-          <Input
-            id="fleet-stop-label-input"
-            list="fleet-stop-label-suggestions"
+          <LabelAutocomplete
             value={labelName}
-            onChange={(e) => setLabelName(e.target.value)}
-            placeholder="e.g. production"
-            className="h-9 text-sm"
+            onChange={setLabelName}
+            suggestions={knownLabelNames}
             disabled={running}
+            placeholder="e.g. production"
           />
-          <datalist id="fleet-stop-label-suggestions">
-            {knownLabelNames.map(n => <option key={n} value={n} />)}
-          </datalist>
         </SheetSection>
 
         {previewSection}
@@ -308,3 +303,91 @@ function PreviewWell({ perNode }: PreviewWellProps) {
     </div>
   );
 }
+
+interface LabelAutocompleteProps {
+  value: string;
+  onChange: (next: string) => void;
+  suggestions: string[];
+  disabled?: boolean;
+  placeholder?: string;
+}
+
+// Free-form text input with a Sencho-styled suggestion popover. Replaces the
+// browser-native <datalist> so the dropdown matches the rest of the kit (same
+// surface tokens as <Combobox>). The operator can still type a label name
+// that was not in the suggestions list; the server-side match-preview will
+// resolve it or report 0 nodes match.
+function LabelAutocomplete({ value, onChange, suggestions, disabled, placeholder }: LabelAutocompleteProps) {
+  const [open, setOpen] = useState(false);
+  const wrapperRef = useRef<HTMLDivElement>(null);
+
+  const filtered = useMemo(() => {
+    const q = value.trim().toLowerCase();
+    if (q.length === 0) return suggestions;
+    return suggestions.filter(s => s.toLowerCase().includes(q));
+  }, [value, suggestions]);
+
+  useEffect(() => {
+    if (!open) return;
+    const onClick = (e: MouseEvent) => {
+      if (wrapperRef.current && !wrapperRef.current.contains(e.target as Node)) {
+        setOpen(false);
+      }
+    };
+    const onKey = (e: KeyboardEvent) => {
+      if (e.key === 'Escape') {
+        e.stopPropagation();
+        setOpen(false);
+      }
+    };
+    document.addEventListener('mousedown', onClick);
+    document.addEventListener('keydown', onKey, true);
+    return () => {
+      document.removeEventListener('mousedown', onClick);
+      document.removeEventListener('keydown', onKey, true);
+    };
+  }, [open]);
+
+  const handleSelect = (next: string) => {
+    onChange(next);
+    setOpen(false);
+  };
+
+  return (
+    <div ref={wrapperRef} className="relative">
+      <Input
+        id="fleet-stop-label-input"
+        value={value}
+        onChange={(e) => {
+          onChange(e.target.value);
+          if (!open) setOpen(true);
+        }}
+        onFocus={() => { if (!disabled) setOpen(true); }}
+        placeholder={placeholder}
+        className="h-9 text-sm"
+        disabled={disabled}
+        autoComplete="off"
+        spellCheck={false}
+      />
+      {open && filtered.length > 0 && (
+        <div className="absolute left-0 top-full mt-1 z-50 w-full rounded-md border border-glass-border bg-popover text-popover-foreground shadow-md backdrop-blur-[10px] backdrop-saturate-[1.15]">
+          <ul className="max-h-[200px] overflow-y-auto overflow-x-hidden p-1">
+            {filtered.map((s) => (
+              <li key={s}>
+                <button
+                  type="button"
+                  // mousedown + preventDefault keeps the input focused so the
+                  // selection registers before any blur-driven close fires.
+                  onMouseDown={(e) => { e.preventDefault(); handleSelect(s); }}
+                  className="flex w-full items-center rounded-sm px-2 py-1.5 font-mono text-xs text-stat-value hover:bg-accent hover:text-accent-foreground"
+                >
+                  {s}
+                </button>
+              </li>
+            ))}
+          </ul>
+        </div>
+      )}
+    </div>
+  );
+}

frontend/src/components/ui/fleet-action-card.tsx

@@ -12,6 +12,14 @@ export type FleetActionClass = 'destructive' | 'transformative' | 'maintenance';
 export type BlastRadiusTone = 'warning' | 'success' | 'muted';
 export type PrimaryActionVariant = 'primary' | 'destructive';
 
+/**
+ * System-Sheet recipe card for the Fleet Actions tab (audit §18, DESIGN §10).
+ *
+ * Layout note: the outer <Card> is `flex flex-col h-full` and the body slot
+ * is `flex-1`, so when a parent gives the card explicit height (e.g. the
+ * equalized-row wrapper in FleetActionsTab.tsx), the body grows and the
+ * footer pins to the bottom. In a content-sized parent this is a no-op.
+ */
 export interface FleetActionCardProps {
   /** Crumb segments. Last segment renders in --stat-title; the rest in --stat-subtitle with separators. */
   crumb: string[];
@@ -107,7 +115,7 @@ export function FleetActionCard(props: FleetActionCardProps) {
   const headCrumbs = crumb.slice(0, -1);
 
   return (
-    <Card className="relative overflow-hidden p-0">
+    <Card className="relative overflow-hidden p-0 flex flex-col h-full">
       <span
         aria-hidden="true"
         className="absolute inset-y-0 left-0 w-[3px] bg-brand"
@@ -166,7 +174,7 @@ export function FleetActionCard(props: FleetActionCardProps) {
         />
       </div>
 
-      <div className="px-6">
+      <div className="px-6 flex-1">
         {children}
       </div>