feat(crown): note that round-bounded panels refresh every ~2h

src/components/layout/AppLayout.tsx

@@ -4,6 +4,7 @@ import { Outlet } from 'react-router-dom';
 import { useOnNavigate, useSSE } from '../../hooks';
 import LoadingPage from '../../pages/LoadingPage';
 import { TopNav, Footer } from '../nav';
+import HaltBanner from './HaltBanner';
 
 const AppLayout: React.FC = () => {
   // Single SSE subscription for the whole app — every routed page
@@ -22,6 +23,7 @@ const AppLayout: React.FC = () => {
       }}
     >
       <TopNav />
+      <HaltBanner />
       <Stack
         ref={mainRef}
         component="main"

src/components/layout/HaltBanner.tsx

@@ -0,0 +1,51 @@
+import React from 'react';
+import { Box, Typography } from '@mui/material';
+import { useHaltState } from '../../api';
+import { FONTS } from '../../theme';
+
+// Full-width red banner that mounts above every page when the swap
+// contract is halted. The StickyNetworkHeader does carry a tiny
+// "halted" dot, but during a halt no miner earns crown and the full
+// emission pool recycles — that's significant enough to warrant
+// something unmissable. Renders nothing when not halted.
+const HaltBanner: React.FC = () => {
+  const { data: halt } = useHaltState();
+  if (!halt?.halted) return null;
+
+  return (
+    <Box
+      role="alert"
+      sx={{
+        width: '100%',
+        backgroundColor: 'warning.main',
+        color: 'warning.contrastText',
+        py: 1,
+        px: { xs: 2, md: 4 },
+        borderBottom: '1px solid',
+        borderColor: 'warning.dark',
+      }}
+    >
+      <Typography
+        variant="mono"
+        sx={{
+          fontFamily: FONTS.mono,
+          fontSize: '0.78rem',
+          letterSpacing: '0.04em',
+          fontWeight: 600,
+          textAlign: 'center',
+        }}
+      >
+        System is paused for maintenance. Swaps are not being initiated.
+        Emissions are recycling. Scoring will resume when the system is
+        unpaused.
+        {halt.asOfBlock != null && (
+          <Box component="span" sx={{ ml: 1, fontWeight: 400, opacity: 0.85 }}>
+            (as of block #{halt.asOfBlock.toLocaleString()})
+          </Box>
+        )}
+      </Typography>
+    </Box>
+  );
+};
+
+export default HaltBanner;

src/components/layout/index.ts

@@ -1,3 +1,4 @@
 export { default as AppLayout } from './AppLayout';
+export { default as HaltBanner } from './HaltBanner';
 export { default as Page } from './Page';
 export type { PageProps } from './Page';

src/components/miners/StickyNetworkHeader.tsx

@@ -5,9 +5,24 @@ import { useCurrentCrown, useHaltState } from '../../api';
 import CrownIcon from './CrownIcon';
 import { FONTS } from '../../theme';
 
+// Mirrors allways/constants.py SCORING_WINDOW_BLOCKS — the validator
+// flushes crown_holders / rate_history once per round, so most panels
+// only refresh at that cadence. The top-right indicator surfaces the
+// math (last/next) so we don't need to label every panel individually.
+const SCORING_WINDOW_BLOCKS = 600;
+
 const StickyNetworkHeader: React.FC = () => {
   const { data: crown } = useCurrentCrown();
   const { data: halt } = useHaltState();
+  const head = halt?.asOfBlock ?? 0;
+  const lastRefresh =
+    head > 0
+      ? Math.floor(head / SCORING_WINDOW_BLOCKS) * SCORING_WINDOW_BLOCKS
+      : null;
+  const blocksUntilRefresh =
+    lastRefresh != null
+      ? Math.max(0, lastRefresh + SCORING_WINDOW_BLOCKS - head)
+      : null;
 
   const segments: React.ReactNode[] = [];
   if (crown) {
@@ -90,18 +105,49 @@ const StickyNetworkHeader: React.FC = () => {
         <Stack direction="row" spacing={3} alignItems="center" sx={{ flex: 1 }}>
           {segments}
         </Stack>
-        <Stack direction="row" spacing={0.5} alignItems="center">
+        <Stack direction="row" spacing={0.75} alignItems="center">
           <Box
             sx={{
               width: 6,
               height: 6,
               borderRadius: '50%',
-              backgroundColor: halted ? 'error.main' : 'status.active',
+              backgroundColor: halted ? 'warning.main' : 'status.active',
             }}
           />
-          <Typography variant="mono" sx={{ fontSize: '0.72rem' }}>
-            {halted ? 'halted' : 'healthy'}
-          </Typography>
+          {halted ? (
+            <Typography
+              variant="mono"
+              sx={{
+                fontSize: '0.72rem',
+                color: 'warning.main',
+                fontWeight: 600,
+                letterSpacing: '0.04em',
+              }}
+            >
+              paused
+            </Typography>
+          ) : lastRefresh != null ? (
+            <Typography
+              variant="mono"
+              sx={{
+                fontSize: '0.72rem',
+                color: 'text.secondary',
+              }}
+            >
+              last refresh #{lastRefresh.toLocaleString()}
+              <Box component="span" sx={{ mx: 0.5, color: 'text.disabled' }}>
+                ·
+              </Box>
+              next ~{blocksUntilRefresh} blocks
+            </Typography>
+          ) : (
+            <Typography
+              variant="mono"
+              sx={{ fontSize: '0.72rem', color: 'text.secondary' }}
+            >
+              healthy
+            </Typography>
+          )}
         </Stack>
       </Stack>
     </Box>