diff --git a/.gitignore b/.gitignore
index 3835bdc4..82189a45 100644
--- a/.gitignore
+++ b/.gitignore
@@ -61,6 +61,7 @@ playwright-report/
 
 # AI assistant/tooling metadata (keep local, do not track)
 .agent/
+.antigravitycli/
 .cursor/
 .gemini/
 .cursorrules
diff --git a/app/(build-model)/plant/page.tsx b/app/(build-model)/plant/page.tsx
index a91b7848..cbdb8d4c 100644
--- a/app/(build-model)/plant/page.tsx
+++ b/app/(build-model)/plant/page.tsx
@@ -15,7 +15,6 @@ import Stack from '@mui/material/Stack';
 import CircularProgress from '@mui/material/CircularProgress';
 import WarningAmberIcon from '@mui/icons-material/WarningAmber';
 import Dialog from '@mui/material/Dialog';
-import DialogActions from '@mui/material/DialogActions';
 import Link from 'next/link';
 import AuthGuard from '@/components/auth/AuthGuard';
 import { useAuth } from '@/components/auth/AuthProvider';
@@ -461,11 +460,23 @@ export default function BuildModelPlantPage() {
                 maxWidth="sm"
                 fullWidth
             >
-                <DialogActions>
-                    <Button onClick={() => setPlantseedDialogOpen(false)}>
-                        Close
-                    </Button>
-                </DialogActions>
+                <Box sx={{ p: 3 }}>
+                    <Typography variant="h6" fontWeight={600} gutterBottom>
+                        PlantSEED — Update In Progress
+                    </Typography>
+                    <Typography variant="body2" sx={{ color: 'text.secondary', mb: 2 }}>
+                        PlantSEED v2.0 → PlantSEED v3.0
+                    </Typography>
+                    <Alert severity="info" sx={{ mb: 2 }}>
+                        Annotation and reconstruction services are temporarily offline for updates
+                        and will be restored shortly.
+                    </Alert>
+                    <Box sx={{ display: 'flex', justifyContent: 'flex-end' }}>
+                        <Button onClick={() => setPlantseedDialogOpen(false)} variant="contained">
+                            Close
+                        </Button>
+                    </Box>
+                </Box>
             </Dialog>
             </Box>
         </AuthGuard >
diff --git a/app/(reference-data)/biochem/reactions/page.tsx b/app/(reference-data)/biochem/reactions/page.tsx
index 5c41e597..f93a997e 100644
--- a/app/(reference-data)/biochem/reactions/page.tsx
+++ b/app/(reference-data)/biochem/reactions/page.tsx
@@ -17,8 +17,8 @@ import Link from 'next/link';
 import { getReactions, type Reaction, type SolrQueryOpts, EXTERNAL_DBS } from '@/lib/api/biochem';
 import ChemicalEquation from '@/components/ui/ChemicalEquation';
 import IconButton from '@mui/material/IconButton';
-import ChatBubbleOutlineIcon from '@mui/icons-material/ChatBubbleOutline';
-import ReactionCommentModal from '@/components/ui/ReactionCommentModal';
+/* import ChatBubbleOutlineIcon from '@mui/icons-material/ChatBubbleOutline'; */
+/* import ReactionCommentModal from '@/components/ui/ReactionCommentModal'; */
 import { GridHighlightText } from '@/components/GridHighlightText';
 import DataControlHeader from '@/components/layout/DataControlHeader';
 import ExportModal from '@/components/ui/ExportModal';
@@ -272,23 +272,7 @@ export default function ReactionsPage() {
                 </Link>
             ),
         },
-        {
-            field: 'actions',
-            headerName: '',
-            width: 50,
-            sortable: false,
-            disableColumnMenu: true,
-            renderCell: (params) => (
-                <IconButton
-                    size="small"
-                    title="Comment on this reaction"
-                    onClick={() => handleOpenComment(params.row.id)}
-                    sx={{ color: '#00acc1' }}
-                >
-                    <ChatBubbleOutlineIcon fontSize="small" />
-                </IconButton>
-            )
-        },
+        /* comment button column disabled */
         {
             field: 'name',
             headerName: 'Name',
@@ -348,13 +332,7 @@ export default function ReactionsPage() {
                 );
             },
         },
-        {
-            field: 'notes',
-            headerName: 'Notes',
-            width: 100,
-            sortable: false,
-            renderCell: (params) => <GridHighlightText text={(params.row.notes ?? []).join(' | ')} />,
-        },
+        /* notes column disabled */
         {
             field: 'synonyms',
             headerName: 'Synonyms',
@@ -463,11 +441,11 @@ export default function ReactionsPage() {
                 autoHeight
             />
 
-            <ReactionCommentModal
+            {/* <ReactionCommentModal
                 open={commentModalOpen}
                 onClose={() => setCommentModalOpen(false)}
                 reactionId={commentReactionId}
-            />
+            /> */}
 
             <ExportModal
                 open={exportModalOpen}
diff --git a/app/api/maintenance/route.ts b/app/api/maintenance/route.ts
new file mode 100644
index 00000000..ee153a71
--- /dev/null
+++ b/app/api/maintenance/route.ts
@@ -0,0 +1,57 @@
+/**
+ * Maintenance mode status endpoint.
+ *
+ * Returns whether the site is in maintenance mode and an optional message.
+ * Operators can toggle this by:
+ *   1. Creating /tmp/maintenance.json with {"enabled":true,"message":"..."}
+ *      (file is checked at runtime, no restart needed)
+ *   2. Setting MAINTENANCE_MODE env var (requires container restart)
+ */
+import { NextResponse } from 'next/server';
+import fs from 'fs';
+
+const NO_CACHE_HEADERS = { 'Cache-Control': 'no-store, max-age=0' };
+
+interface MaintenanceStatus {
+    enabled: boolean;
+    message: string;
+}
+
+function readFileStatus(): MaintenanceStatus | null {
+    try {
+        const raw = fs.readFileSync('/tmp/maintenance.json', 'utf-8');
+        const data = JSON.parse(raw);
+        if (data && typeof data.enabled === 'boolean') {
+            return {
+                enabled: data.enabled,
+                message: typeof data.message === 'string' ? data.message : '',
+            };
+        }
+    } catch {
+        // File doesn't exist or invalid — ignore
+    }
+    return null;
+}
+
+export async function GET(): Promise<NextResponse> {
+    // 1. Check file-based toggle first (runtime toggle, no restart needed)
+    const fileStatus = readFileStatus();
+    if (fileStatus) {
+        return NextResponse.json(fileStatus, { headers: NO_CACHE_HEADERS });
+    }
+
+    // 2. Fall back to env var (requires container restart)
+    const envEnabled = process.env.MAINTENANCE_MODE === 'true' || process.env.MAINTENANCE_MODE === '1';
+    if (envEnabled) {
+        return NextResponse.json({
+            enabled: true,
+            message: process.env.MAINTENANCE_MESSAGE || 'Site is undergoing maintenance. Please check back shortly.',
+        }, { headers: NO_CACHE_HEADERS });
+    }
+
+    // 3. Default: not in maintenance
+    return NextResponse.json(
+        { enabled: false, message: '' },
+        { headers: NO_CACHE_HEADERS },
+    );
+}
diff --git a/app/layout.tsx b/app/layout.tsx
index 9a472634..25487af4 100644
--- a/app/layout.tsx
+++ b/app/layout.tsx
@@ -4,6 +4,7 @@ import CssBaseline from '@mui/material/CssBaseline';
 import theme from '@/lib/theme';
 import Box from '@mui/material/Box';
 import HeaderLayoutRouter from '@/app/HeaderLayoutRouter';
+import OutageBanner from '@/components/ui/OutageBanner';
 import Providers from '@/components/Providers';
 import { AuthProvider } from '@/components/auth/AuthProvider';
 import type { Metadata } from "next";
@@ -35,6 +36,7 @@ export default function RootLayout({
                         <Providers>
                             <AuthProvider>
                                 <CssBaseline />
+                                <OutageBanner />
                                 <HeaderLayoutRouter />
                                 <Box
                                     component="main"
diff --git a/components/ui/OutageBanner.tsx b/components/ui/OutageBanner.tsx
new file mode 100644
index 00000000..113c65ff
--- /dev/null
+++ b/components/ui/OutageBanner.tsx
@@ -0,0 +1,45 @@
+'use client';
+
+import { useEffect, useState } from 'react';
+import Box from '@mui/material/Box';
+import Typography from '@mui/material/Typography';
+import Alert from '@mui/material/Alert';
+
+interface MaintenanceStatus {
+    enabled: boolean;
+    message: string;
+}
+
+export default function OutageBanner() {
+    const [status, setStatus] = useState<MaintenanceStatus | null>(null);
+
+    useEffect(() => {
+        fetch('/api/maintenance', { cache: 'no-store' })
+            .then((res) => {
+                if (!res.ok) throw new Error(`HTTP ${res.status}`);
+                return res.json();
+            })
+            .then((data: MaintenanceStatus) => setStatus(data))
+            .catch(() => setStatus({ enabled: false, message: '' }));
+    }, []);
+
+    if (!status || !status.enabled) return null;
+
+    return (
+        <Box sx={{ width: '100%' }}>
+            <Alert
+                severity="warning"
+                sx={{
+                    borderRadius: 0,
+                    textAlign: 'center',
+                    justifyContent: 'center',
+                    '& .MuiAlert-message': { flex: 'unset' },
+                }}
+            >
+                <Typography variant="body1" fontWeight={600}>
+                    {status.message || 'Site is undergoing maintenance. Please check back shortly.'}
+                </Typography>
+            </Alert>
+        </Box>
+    );
+}