diff --git a/package-lock.json b/package-lock.json
index 018dac1..2dd38e9 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -27,7 +27,7 @@
         "@vitejs/plugin-react": "^6.0.1",
         "eslint": "^10.7.0",
         "eslint-config-prettier": "^10.1.8",
-        "eslint-plugin-react-hooks": "^7.0.1",
+        "eslint-plugin-react-hooks": "^7.1.1",
         "eslint-plugin-react-refresh": "^0.5.3",
         "globals": "^17.6.0",
         "identity-obj-proxy": "^3.0.0",
@@ -1972,9 +1972,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1992,9 +1989,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -2012,9 +2006,6 @@
         "ppc64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -2032,9 +2023,6 @@
         "s390x"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -2052,9 +2040,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -2072,9 +2057,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -3328,9 +3310,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -3345,9 +3324,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -3362,9 +3338,6 @@
         "loong64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -3379,9 +3352,6 @@
         "loong64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -3396,9 +3366,6 @@
         "ppc64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -3413,9 +3380,6 @@
         "riscv64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -3430,9 +3394,6 @@
         "riscv64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -3447,9 +3408,6 @@
         "s390x"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -3464,9 +3422,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -3481,9 +3436,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -4854,9 +4806,9 @@
       }
     },
     "node_modules/eslint-plugin-react-hooks": {
-      "version": "7.0.1",
-      "resolved": "https://registry.npmjs.org/eslint-plugin-react-hooks/-/eslint-plugin-react-hooks-7.0.1.tgz",
-      "integrity": "sha512-O0d0m04evaNzEPoSW+59Mezf8Qt0InfgGIBJnpC0h3NH/WjUAR7BIKUfysC6todmtiZ/A0oUVS8Gce0WhBrHsA==",
+      "version": "7.1.1",
+      "resolved": "https://registry.npmjs.org/eslint-plugin-react-hooks/-/eslint-plugin-react-hooks-7.1.1.tgz",
+      "integrity": "sha512-f2I7Gw6JbvCexzIInuSbZpfdQ44D7iqdWX01FKLvrPgqxoE7oMj8clOfto8U6vYiz4yd5oKu39rRSVOe1zRu0g==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -4870,7 +4822,7 @@
         "node": ">=18"
       },
       "peerDependencies": {
-        "eslint": "^3.0.0 || ^4.0.0 || ^5.0.0 || ^6.0.0 || ^7.0.0 || ^8.0.0-0 || ^9.0.0"
+        "eslint": "^3.0.0 || ^4.0.0 || ^5.0.0 || ^6.0.0 || ^7.0.0 || ^8.0.0-0 || ^9.0.0 || ^10.0.0"
       }
     },
     "node_modules/eslint-plugin-react-refresh": {
diff --git a/package.json b/package.json
index f6b47f6..54840f8 100644
--- a/package.json
+++ b/package.json
@@ -47,7 +47,7 @@
     "@vitejs/plugin-react": "^6.0.1",
     "eslint": "^10.7.0",
     "eslint-config-prettier": "^10.1.8",
-    "eslint-plugin-react-hooks": "^7.0.1",
+    "eslint-plugin-react-hooks": "^7.1.1",
     "eslint-plugin-react-refresh": "^0.5.3",
     "globals": "^17.6.0",
     "identity-obj-proxy": "^3.0.0",
diff --git a/src/providers/BackendContext.tsx b/src/providers/BackendContext.tsx
index 6df888b..b0f52a6 100644
--- a/src/providers/BackendContext.tsx
+++ b/src/providers/BackendContext.tsx
@@ -78,6 +78,26 @@ function envUrls(): Partial<Record<BackendId, string>> {
   return urls;
 }
 
+// ---------------------------------------------------------------------------
+// Pure helper — no setState, safe to call from effects via .then()
+// ---------------------------------------------------------------------------
+
+async function fetchHealthStatus(
+  url: string
+): Promise<{ connected: boolean; error: string | null }> {
+  try {
+    const res = await fetch(`${url}/health`, { signal: AbortSignal.timeout(5000) });
+    return res.ok
+      ? { connected: true, error: null }
+      : { connected: false, error: `Health check returned ${res.status}` };
+  } catch (err) {
+    return {
+      connected: false,
+      error: err instanceof Error ? err.message : 'Cannot reach backend',
+    };
+  }
+}
+
 // ---------------------------------------------------------------------------
 // Provider component
 // ---------------------------------------------------------------------------
@@ -100,7 +120,7 @@ export function BackendProvider({ children }: { children: ReactNode }) {
     backendId === 'local' || backendId === 'js' ? true : null
   );
   const [connectionError, setConnectionError] = useState<string | null>(null);
-  const [checking, setChecking] = useState(false);
+  const [checking, setChecking] = useState<boolean>(backendId !== 'local' && backendId !== 'js');
 
   // Build configs with URL overrides
   const backends = useMemo<Record<BackendId, BackendConfig>>(() => {
@@ -121,7 +141,7 @@ export function BackendProvider({ children }: { children: ReactNode }) {
     return new RemoteProvider(backendId, url);
   }, [backendId, backends]);
 
-  // Health check for remote backends
+  // Health check for remote backends — called from event handlers (onClick), not effects
   const checkConnection = useCallback(async () => {
     if (backendId === 'local' || backendId === 'js') {
       setConnected(true);
@@ -131,27 +151,32 @@ export function BackendProvider({ children }: { children: ReactNode }) {
     setChecking(true);
     const cfg = backends[backendId];
     const url = cfg.url ?? BACKEND_PRESETS[backendId].url ?? '';
-    try {
-      const res = await fetch(`${url}/health`, { signal: AbortSignal.timeout(5000) });
-      if (res.ok) {
-        setConnected(true);
-        setConnectionError(null);
-      } else {
-        setConnected(false);
-        setConnectionError(`Health check returned ${res.status}`);
-      }
-    } catch (err) {
-      setConnected(false);
-      setConnectionError(err instanceof Error ? err.message : 'Cannot reach backend');
-    } finally {
-      setChecking(false);
-    }
+    const result = await fetchHealthStatus(url);
+    setConnected(result.connected);
+    setConnectionError(result.error);
+    setChecking(false);
   }, [backendId, backends]);
 
-  // Auto-check when backend changes
+  // Auto-check when backend changes — setState only in .then() callback, never synchronously
   useEffect(() => {
-    checkConnection();
-  }, [checkConnection]);
+    if (backendId === 'local' || backendId === 'js') return;
+
+    let ignore = false;
+    const cfg = backends[backendId];
+    const url = cfg.url ?? BACKEND_PRESETS[backendId].url ?? '';
+
+    fetchHealthStatus(url).then((result) => {
+      if (!ignore) {
+        setConnected(result.connected);
+        setConnectionError(result.error);
+        setChecking(false);
+      }
+    });
+
+    return () => {
+      ignore = true;
+    };
+  }, [backendId, backends]);
 
   // Persist backend choice
   useEffect(() => {
@@ -169,6 +194,7 @@ export function BackendProvider({ children }: { children: ReactNode }) {
     }
     setConnected(id === 'local' ? true : null);
     setConnectionError(null);
+    setChecking(id !== 'local' && id !== 'js');
     setBackendId(id);
   }, []);