Add the notes hook and its IPC wrappers

app/src/hooks/useNotes.ts

@@ -0,0 +1,131 @@
+import { useCallback, useEffect, useRef, useState } from "react";
+import * as commands from "../lib/tauri-commands";
+import type { Note } from "../lib/types";
+import type { SaveState } from "./useSaveState";
+import { useAppState } from "../store/appState";
+
+/** A blank note, ordered to the top so the user can start typing immediately. */
+function draft(): Note {
+  const now = new Date().toISOString();
+  return {
+    // The backend owns the real id; this one only has to be unique enough to
+    // key the list until the first save returns.
+    id: crypto.randomUUID(),
+    title: "",
+    body: "",
+    pinned: false,
+    created_at: now,
+    updated_at: now,
+  };
+}
+
+/**
+ * A project's notes, cached from the backend.
+ *
+ * The backend is the source of truth and this is a cache — every mutation goes
+ * through a command and the returned record replaces the local one, so the
+ * list can never drift from the file. `saveState` mirrors `useProjectSave` so
+ * `ui/SaveIndicator` can report the outcome: a save that fails silently is a
+ * user staring at text they believe is stored.
+ */
+export function useNotes(projectId: string) {
+  const [notes, setNotes] = useState<Note[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [saveState, setSaveState] = useState<SaveState>({ status: "idle", error: null });
+  const pushToast = useAppState((s) => s.pushToast);
+  const resetTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
+
+  useEffect(() => {
+    if (!projectId) {
+      setNotes([]);
+      setLoading(false);
+      return;
+    }
+    let cancelled = false;
+    setLoading(true);
+    commands
+      .listNotes(projectId)
+      .then((loaded) => {
+        if (!cancelled) setNotes(loaded);
+      })
+      .catch((e) => {
+        if (cancelled) return;
+        pushToast({
+          kind: "error",
+          message: "Could not load notes for this project",
+          detail: String(e),
+        });
+      })
+      .finally(() => {
+        if (!cancelled) setLoading(false);
+      });
+    return () => {
+      cancelled = true;
+    };
+  }, [projectId, pushToast]);
+
+  useEffect(
+    () => () => {
+      if (resetTimer.current) clearTimeout(resetTimer.current);
+    },
+    [],
+  );
+
+  const succeeded = useCallback(() => {
+    setSaveState({ status: "saved", error: null });
+    if (resetTimer.current) clearTimeout(resetTimer.current);
+    resetTimer.current = setTimeout(
+      () => setSaveState({ status: "idle", error: null }),
+      2500,
+    );
+  }, []);
+
+  const saveNote = useCallback(
+    async (note: Note) => {
+      if (resetTimer.current) clearTimeout(resetTimer.current);
+      setSaveState({ status: "saving", error: null });
+      try {
+        const saved = await commands.saveNote(projectId, note);
+        setNotes((current) => {
+          const index = current.findIndex((n) => n.id === saved.id);
+          if (index === -1) return [saved, ...current];
+          const next = [...current];
+          next[index] = saved;
+          return next;
+        });
+        succeeded();
+        return true;
+      } catch (e) {
+        const message = String(e);
+        setSaveState({ status: "failed", error: message });
+        pushToast({ kind: "error", message: "Could not save note", detail: message });
+        return false;
+      }
+    },
+    [projectId, pushToast, succeeded],
+  );
+
+  const createNote = useCallback(async () => {
+    const note = draft();
+    // Held locally first so the editor can focus it immediately; the save
+    // happens on blur like every other edit.
+    setNotes((current) => [note, ...current]);
+    return note;
+  }, []);
+
+  const deleteNote = useCallback(
+    async (noteId: string) => {
+      try {
+        await commands.deleteNote(projectId, noteId);
+        setNotes((current) => current.filter((n) => n.id !== noteId));
+        return true;
+      } catch (e) {
+        pushToast({ kind: "error", message: "Could not delete note", detail: String(e) });
+        return false;
+      }
+    },
+    [projectId, pushToast],
+  );
+
+  return { notes, loading, saveState, createNote, saveNote, deleteNote };
+}