feat(notes): add note model and storage layer

src/lib/notesStorage.test.ts

@@ -0,0 +1,60 @@
+import { beforeEach, describe, expect, it } from 'vitest'
+import { loadNotes, saveNotes } from './notesStorage'
+import type { Note } from '../types'
+
+const STORAGE_KEY = 'notes'
+
+describe('notesStorage', () => {
+  beforeEach(() => {
+    localStorage.clear()
+  })
+
+  it('loads an empty array when nothing is stored', () => {
+    expect(loadNotes()).toEqual([])
+  })
+
+  it('saves and loads notes', () => {
+    const notes: Note[] = [
+      { id: 1, title: 'Courses', content: 'Lait, oeufs' },
+      { id: 2, title: 'Pense-bête', content: 'Rappeler le plombier' },
+    ]
+
+    saveNotes(notes)
+
+    expect(JSON.parse(localStorage.getItem(STORAGE_KEY)!)).toEqual(notes)
+    expect(loadNotes()).toEqual(notes)
+  })
+
+  it('returns an empty array when the stored JSON is invalid', () => {
+    localStorage.setItem(STORAGE_KEY, 'not json {')
+    expect(loadNotes()).toEqual([])
+  })
+
+  it('returns an empty array when the stored value is not an array', () => {
+    localStorage.setItem(STORAGE_KEY, JSON.stringify({ id: 1, title: 'x', content: 'y' }))
+    expect(loadNotes()).toEqual([])
+  })
+
+  it('filters out entries that do not match the Note shape', () => {
+    localStorage.setItem(
+      STORAGE_KEY,
+      JSON.stringify([
+        { id: 1, title: 'ok', content: 'ok' },
+        { id: '2', title: 'bad id', content: 'x' },
+        { title: 'missing id', content: 'x' },
+        'nope',
+      ]),
+    )
+
+    expect(loadNotes()).toEqual([{ id: 1, title: 'ok', content: 'ok' }])
+  })
+
+  it('overwrites previously stored notes', () => {
+    saveNotes([{ id: 1, title: 'A', content: 'a' }])
+    const updated: Note[] = [{ id: 2, title: 'B', content: 'b' }]
+
+    saveNotes(updated)
+
+    expect(loadNotes()).toEqual(updated)
+  })
+})

src/lib/notesStorage.ts

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+import type { Note } from '../types'
+
+const STORAGE_KEY = 'notes'
+
+export function loadNotes(): Note[] {
+  const raw = localStorage.getItem(STORAGE_KEY)
+  if (raw === null) return []
+
+  try {
+    const parsed: unknown = JSON.parse(raw)
+    if (!Array.isArray(parsed)) return []
+    return parsed.filter(isNote)
+  } catch {
+    return []
+  }
+}
+
+export function saveNotes(notes: Note[]): void {
+  localStorage.setItem(STORAGE_KEY, JSON.stringify(notes))
+}
+
+function isNote(value: unknown): value is Note {
+  if (typeof value !== 'object' || value === null) return false
+  const candidate = value as Record<string, unknown>
+  return (
+    typeof candidate.id === 'number' &&
+    typeof candidate.title === 'string' &&
+    typeof candidate.content === 'string'
+  )
+}

src/types.ts

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+export interface Note {
+  id: number
+  title: string
+  content: string
+}