fix(ai): disable categorization when last model is deleted

When the last AI model is deleted, categorization is now forced
off server-side, preventing it from silently restarting when a
new model is added. The frontend distinguishes between loading
and no connections, hiding the feature toggle instead of
disabling it, and removes the unused "Add a model first" message.

backend/src/routes/settings.ts

@@ -744,8 +744,11 @@ router.delete(
   requireAdmin,
   asyncHandler(async (req, res) => {
     await deleteAiConnection(req.params.id);
-    // A feature set to it goes back to the default.
-    if ((await getAiCategorizationPrefs()).aiConnectionId === req.params.id) {
+    // With no model left every feature switches off, so adding one later doesn't quietly start them again.
+    if (!(await listAiConnections()).length) {
+      await setAiCategorizationPrefs({ enabled: false, aiConnectionId: null });
+    } else if ((await getAiCategorizationPrefs()).aiConnectionId === req.params.id) {
+      // A feature set to it goes back to the default.
       await setAiCategorizationPrefs({ aiConnectionId: null });
     }
     res.status(204).end();

backend/tests/aiCategorization.test.ts

@@ -406,6 +406,10 @@ describe("AI categorization", () => {
     const remaining = await request(app).get("/api/settings/ai-connections").set(auth());
     expect(remaining.body).toMatchObject([{ id: third.id, is_default: true }]);
 
+    // Deleting the last model switches the features off.
+    await request(app).delete(`/api/settings/ai-connections/${third.id}`).set(auth());
+    expect((await request(app).get("/api/settings/ai-categorization").set(auth())).body.enabled).toBe(false);
+
     const unknown = await request(app)
       .patch("/api/settings/ai-categorization")
       .set(auth())

frontend/src/i18n/locales/en.json

@@ -659,8 +659,7 @@
         "categorization": "AI Categorization",
         "openSettings": "Settings",
         "settingsAria": "{{feature}} settings",
-        "toggleAria": "Turn {{feature}} on or off",
-        "needsModel": "Add a model first"
+        "toggleAria": "Turn {{feature}} on or off"
       },
       "aiCategorization": {
         "heading": "AI Categorization",

frontend/src/i18n/locales/lt.json

@@ -663,8 +663,7 @@
         "categorization": "DI kategorizavimas",
         "openSettings": "Nustatymai",
         "settingsAria": "{{feature}} nustatymai",
-        "toggleAria": "Įjungti arba išjungti: {{feature}}",
-        "needsModel": "Pirmiausia pridėkite modelį"
+        "toggleAria": "Įjungti arba išjungti: {{feature}}"
       },
       "aiCategorization": {
         "heading": "DI kategorizavimas",

frontend/src/pages/AiPage/AiFeaturesSection.tsx

@@ -16,7 +16,8 @@ import AiCategorizationDialog from "./AiCategorizationDialog";
 import CategorizationAnimation from "./CategorizationAnimation";
 import { AiLogo } from "./aiLogos";
 
-type Props = { connections: AiConnection[]; onUnauthorized?: () => void };
+/** `connections` is null while the models are loading. */
+type Props = { connections: AiConnection[] | null; onUnauthorized?: () => void };
 
 const TILE = 112;
 const tileShadow = "inset 0 0 0 1px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.04)";
@@ -29,7 +30,10 @@ export default function AiFeaturesSection({ connections, onUnauthorized }: Props
   const [switching, setSwitching] = useState(false);
   const [error, setError] = useState<string | null>(null);
 
+  // Read again when models come or go: deleting the last one switches the features off on the server.
+  const modelCount = connections?.length;
   useEffect(() => {
+    if (modelCount === undefined) return;
     let active = true;
     void settingsApi
       .getAiCategorization()
@@ -43,7 +47,7 @@ export default function AiFeaturesSection({ connections, onUnauthorized }: Props
     return () => {
       active = false;
     };
-  }, [onUnauthorized, t]);
+  }, [modelCount, onUnauthorized, t]);
 
   const toggle = async (enabled: boolean) => {
     setSwitching(true);
@@ -60,15 +64,17 @@ export default function AiFeaturesSection({ connections, onUnauthorized }: Props
 
   // The AI it would use: the one it's set to while that exists, otherwise the default, as the backend picks.
   const model =
-    connections.find((connection) => connection.id === settings?.ai_connection_id) ??
-    connections.find((connection) => connection.is_default);
-  const enabled = Boolean(settings?.enabled);
+    connections?.find((connection) => connection.id === settings?.ai_connection_id) ??
+    connections?.find((connection) => connection.is_default);
+  const hasModel = Boolean(connections?.length);
+  // Without a model nothing can run, whatever was saved, and there's nothing to switch on until one is added.
+  const enabled = Boolean(settings?.enabled) && hasModel;
   const label = t("adminSettings.aiFeatures.categorization");
 
   return (
     <Stack spacing={3}>
       <SectionHeader title={t("adminSettings.aiFeatures.heading")} subtitle={t("adminSettings.aiFeatures.subtitle")} />
-      {settings === null && !error ? (
+      {(settings === null || connections === null) && !error ? (
         <CircularProgress size={20} />
       ) : (
         <Box>
@@ -122,19 +128,17 @@ export default function AiFeaturesSection({ connections, onUnauthorized }: Props
                 <Typography variant="body2" fontWeight={600}>
                   {label}
                 </Typography>
-                <Tooltip title={connections.length ? "" : t("adminSettings.aiFeatures.needsModel")}>
-                  <span>
-                    <Switch
-                      size="small"
-                      checked={enabled}
-                      onChange={(event) => void toggle(event.target.checked)}
-                      disabled={!settings || switching || (!connections.length && !enabled)}
-                      slotProps={{
-                        input: { "aria-label": t("adminSettings.aiFeatures.toggleAria", { feature: label }) },
-                      }}
-                    />
-                  </span>
-                </Tooltip>
+                {hasModel && (
+                  <Switch
+                    size="small"
+                    checked={enabled}
+                    onChange={(event) => void toggle(event.target.checked)}
+                    disabled={!settings || switching}
+                    slotProps={{
+                      input: { "aria-label": t("adminSettings.aiFeatures.toggleAria", { feature: label }) },
+                    }}
+                  />
+                )}
               </Stack>
             </Stack>
           </Box>
@@ -151,7 +155,7 @@ export default function AiFeaturesSection({ connections, onUnauthorized }: Props
       {open && settings && (
         <AiCategorizationDialog
           settings={settings}
-          connections={connections}
+          connections={connections ?? []}
           onClose={() => setOpen(false)}
           onSaved={setSettings}
           onUnauthorized={onUnauthorized}

frontend/src/pages/AiPage/index.tsx

@@ -28,7 +28,7 @@ export default function AiPage({ onUnauthorized }: Props) {
   return (
     <Stack spacing={4} divider={<Divider />}>
       <AiConnectionsSection connections={connections} onChanged={load} onUnauthorized={onUnauthorized} />
-      <AiFeaturesSection connections={connections ?? []} onUnauthorized={onUnauthorized} />
+      <AiFeaturesSection connections={connections} onUnauthorized={onUnauthorized} />
     </Stack>
   );
 }