fix(drain-plan): focusable caveat trigger; drop stale ack at refresh time

The estimate-caveat tooltip trigger is now a button, so keyboard focus
opens it (the Tooltip already handles focus/blur). The emptyDir
acknowledgement is cleared synchronously when refresh is clicked rather
than by the effect that watches generatedAt, which runs a paint after
the refreshed plan renders and would leave one frame where a stale
acknowledgement still enables Drain.

Claude-Session: https://claude.ai/code/session_01NE55VsYGkb5tV3neKDmtZw

Author: hisco

packages/k8s-ui/src/components/shared/DrainPlanDialog.test.tsx

@@ -120,6 +120,11 @@ describe('DrainPlanContent', () => {
     expect(render({ plan: p })).not.toContain('Recompute the plan')
   })
 
+  it('exposes the estimate caveat on a focusable trigger', () => {
+    const html = render({ plan: plan([pod('web', 'evict')]) })
+    expect(html).toMatch(/<button[^>]*aria-label="About this estimate"/)
+  })
+
   it('offers a retry on a failed plan only when the host can recompute it', () => {
     expect(render({ error: 'boom', onRefreshPlan: noop })).toContain('Try again')
     expect(render({ error: 'boom' })).not.toContain('Try again')

packages/k8s-ui/src/components/shared/DrainPlanDialog.tsx

@@ -178,7 +178,13 @@ export function DrainPlanContent({
             <div className="flex items-center gap-1 shrink-0 text-xs text-theme-text-tertiary">
               <span>Estimated at {new Date(current.generatedAt).toLocaleTimeString()}</span>
               <Tooltip content={ESTIMATE_CAVEAT} className="max-w-xs">
-                <Info aria-label="About this estimate" className="w-3.5 h-3.5" />
+                <button
+                  type="button"
+                  aria-label="About this estimate"
+                  className="p-0.5 rounded text-theme-text-tertiary transition-colors hover:text-theme-text-secondary"
+                >
+                  <Info className="w-3.5 h-3.5" />
+                </button>
               </Tooltip>
               {onRefreshPlan && (
                 <Tooltip content="Recompute the plan">
@@ -280,6 +286,16 @@ export function DrainPlanDialog({
     setAcknowledgedEmptyDir(false)
   }, [options.force, options.deleteEmptyDirData, open, plan?.generatedAt])
 
+  // Drop the acknowledgement at click time, not when the refreshed plan lands:
+  // the effect above runs a paint after the new plan renders, which would leave
+  // one frame where a stale acknowledgement still enables Drain.
+  const refreshPlan = onRefreshPlan
+    ? () => {
+        setAcknowledgedEmptyDir(false)
+        onRefreshPlan()
+      }
+    : undefined
+
   const confirmEnabled = canConfirmDrain({ plan, nodeName, options, loading, error, acknowledgedEmptyDir, planSupported })
 
   return (
@@ -306,7 +322,7 @@ export function DrainPlanDialog({
         planSupported={planSupported}
         acknowledgedEmptyDir={acknowledgedEmptyDir}
         onAcknowledgeEmptyDir={setAcknowledgedEmptyDir}
-        onRefreshPlan={onRefreshPlan}
+        onRefreshPlan={refreshPlan}
       />
     </ConfirmDialog>
   )