first commit of v.02 application

client/src/hooks/useNotebook.js

@@ -0,0 +1,50 @@
+import { useState, useEffect, useCallback } from 'react';
+import * as notebooksApi from '../api/notebooks.js';
+
+export function useNotebook() {
+  const [notebooks, setNotebooks] = useState([]);
+  const [activeNotebook, setActiveNotebook] = useState(null);
+
+  useEffect(() => {
+    notebooksApi.listNotebooks().then(setNotebooks).catch(console.error);
+  }, []);
+
+  const selectNotebook = useCallback(
+    (id) => {
+      const nb = notebooks.find((n) => n.id === id) || null;
+      setActiveNotebook(nb);
+    },
+    [notebooks],
+  );
+
+  const createNotebook = useCallback(async (name) => {
+    if (!name) return;
+    const nb = await notebooksApi.createNotebook(name);
+    setNotebooks((prev) => [...prev, nb]);
+    setActiveNotebook(nb);
+  }, []);
+
+  const deleteNotebook = useCallback(
+    async (id) => {
+      try {
+        await notebooksApi.deleteNotebook(id);
+      } catch (err) {
+        console.error('Failed to delete notebook', err);
+        return;
+      }
+      setNotebooks((prev) => prev.filter((n) => n.id !== id));
+      if (activeNotebook?.id === id) {
+        setActiveNotebook(null);
+      }
+    },
+    [activeNotebook],
+  );
+
+  return {
+    notebooks,
+    activeNotebook,
+    selectNotebook,
+    createNotebook,
+    deleteNotebook,
+  };
+}