test: split Nostr backup integration cases

src/lnurlcash/nostrBackup.restore.cases.ts

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+// Nostr backup: key derivation stability, event build/parse round-trips,
+// tamper rejection, publish/fetch and restore against an in-memory relay
+// (the transport is injected - no network), and the debounced publisher.
+
+import {afterEach, beforeEach, describe, expect, it, vi} from 'vitest'
+import {bytesToHex} from '@noble/hashes/utils.js'
+import type {NostrEvent} from 'nostr-tools/core'
+import {finalizeEvent, getPublicKey} from 'nostr-tools/pure'
+import {v2 as nip44v2} from 'nostr-tools/nip44'
+import {buildNoteUrl} from 'lnurlcash-kit'
+
+import {deriveBearerAesKey, linkingPubKeyHex, saveLinkingKey} from './keys'
+import {
+  BACKUP_EVENT_KIND,
+  backupPubkey,
+  buildBackupEvent,
+  buildBackupEvents,
+  createBackupPublisher,
+  deriveBackupKey,
+  fetchBackup,
+  parseBackupEvent,
+  publishBackup,
+  restoreFromNostr,
+} from './nostrBackup'
+import type {BackupPartPayload, BackupTransport} from './nostrBackup'
+import {
+  loadBearers,
+  loadSettings,
+  mergeBearers,
+  persistBearer,
+  persistSettings,
+  readEncryptedBearers,
+} from './storage'
+import type {Bearer} from './types'
+import {addTrustedMint, isMintUnconfirmed, readTrustedMints} from './trustedMints'
+import {requiredValue, stubLocalStorage} from './test-utils'
+
+const LINKING_KEY = new Uint8Array(32).fill(7)
+const OTHER_KEY = new Uint8Array(32).fill(9)
+const OWNER_ID = linkingPubKeyHex(LINKING_KEY)
+
+const K1_A = 'aa'.repeat(32)
+const K1_B = 'bb'.repeat(32)
+const MINT_PUBKEY = 'ab'.repeat(33)
+
+// never connected - the recording transport below stands in for the relays
+const RELAYS = ['wss://relay-a.example', 'wss://relay-b.example']
+
+const bearerFixture = (overrides: Partial<Bearer> = {}): Bearer => ({
+  id: 'fixture',
+  url: buildNoteUrl('https://mint.example/w', K1_A, 21_000),
+  callback: 'https://mint.example/w/cb',
+  amount: 21_000,
+  verified: true,
+  createdAt: 1000,
+  updatedAt: 1000,
+  ...overrides,
+})
+
+// an in-memory relay set. It serves EVERY event it ever accepted, older
+// addressable copies included - like a relay that never replaces - which
+// is exactly the case fetchBackup's client-side latest-pick exists for
+const createRecordingTransport = (): {
+  transport: BackupTransport
+  events: NostrEvent[]
+} => {
+  const events: NostrEvent[] = []
+  const transport: BackupTransport = {
+    publish: (_relays, event) => {
+      events.push(event)
+      return Promise.resolve()
+    },
+    fetch: (_relays, filter) =>
+      Promise.resolve(
+        events.filter(
+          (e) =>
+            (!filter.kinds || filter.kinds.includes(e.kind)) &&
+            (!filter.authors || filter.authors.includes(e.pubkey)),
+        ),
+      ),
+  }
+  return {transport, events}
+}
+
+// flips the end of a base64 payload to different-but-valid characters
+const tamperContent = (content: string): string =>
+  content.slice(0, -4) + (content.endsWith('AAAA') ? 'BBBB' : 'AAAA')
+
+beforeEach(() => {
+  stubLocalStorage()
+})
+
+afterEach(() => {
+  vi.useRealTimers()
+})
+
+describe('restoreFromNostr', () => {
+  it('restores notes, mints and settings onto a fresh device through applyBackup', async () => {
+    const aesKey = await deriveBearerAesKey(LINKING_KEY)
+    const secretKey = deriveBackupKey(LINKING_KEY)
+    const {transport} = createRecordingTransport()
+
+    // device A: one note, one trusted mint, one setting - all published
+    await saveLinkingKey(LINKING_KEY)
+    await persistBearer(aesKey, bearerFixture({id: 'note-a'}))
+    await addTrustedMint('mint.example', MINT_PUBKEY, {ownerId: OWNER_ID})
+    persistSettings({defaultMint: 'mint.example'})
+    await publishBackup(
+      secretKey,
+      {
+        notes: readEncryptedBearers(),
+        mints: readTrustedMints(OWNER_ID),
+        settings: loadSettings(),
+      },
+      RELAYS,
+      {transport},
+    )
+
+    // device B: the same seed on empty storage
+    stubLocalStorage()
+    await saveLinkingKey(LINKING_KEY)
+    const result = await restoreFromNostr(LINKING_KEY, RELAYS, {transport})
+
+    expect(result.found).toEqual(['notes', 'mints', 'settings'])
+    expect(result.added).toBe(1)
+    expect(result.trustedMintsAdded).toBe(1)
+    expect(result.settingsRestored).toBe(true)
+    // the linking key is never part of a nostr backup - the seed phrase
+    // the holder entered is its recovery path
+    expect(result.linkingKeyRestored).toBe(false)
+
+    // the note decrypts under this device's bearer key - same seed
+    expect(await loadBearers(aesKey)).toEqual([bearerFixture({id: 'note-a'})])
+    expect(loadSettings()).toEqual({defaultMint: 'mint.example'})
+    // a file/backup-sourced mint pin stays unconfirmed until a live
+    // response corroborates it - nostr restore inherits that rule from
+    // applyBackup unchanged
+    expect(isMintUnconfirmed('mint.example', OWNER_ID)).toBe(true)
+  })
+
+  it('unions records by id and lets a spent copy win after decrypt', async () => {
+    const aesKey = await deriveBearerAesKey(LINKING_KEY)
+    const secretKey = deriveBackupKey(LINKING_KEY)
+    const {transport} = createRecordingTransport()
+
+    // device A publishes its store holding the spendable note
+    await persistBearer(aesKey, bearerFixture({id: 'rec-a'}))
+    await publishBackup(secretKey, {notes: readEncryptedBearers()}, RELAYS, {
+      transport,
+      createdAt: 1000,
+    })
+
+    // device B restores, then marks the same note spent under its OWN
+    // record id, and republishes its full store
+    stubLocalStorage()
+    await restoreFromNostr(LINKING_KEY, RELAYS, {transport})
+    await persistBearer(aesKey, bearerFixture({id: 'rec-b', spent: true, updatedAt: 2000}))
+    await publishBackup(secretKey, {notes: readEncryptedBearers()}, RELAYS, {
+      transport,
+      createdAt: 2000,
+    })
+
+    // device C restores from the final published state
+    stubLocalStorage()
+    const result = await restoreFromNostr(LINKING_KEY, RELAYS, {transport})
+
+    // union by record id: both copies landed
+    expect(result.added).toBe(2)
+    expect(
+      readEncryptedBearers()
+        .map((r) => r.id)
+        .sort(),
+    ).toEqual(['rec-a', 'rec-b'])
+
+    // after decrypt, the note-level merge (same server + k1) collapses
+    // them, and the spent copy wins even though its record is the newer
+    // arrival - a restored backup must never resurrect spendable money
+    const merged = mergeBearers([], await loadBearers(aesKey))
+    expect(merged).toHaveLength(1)
+    expect(requiredValue(merged[0]).id).toBe('rec-b')
+    expect(requiredValue(merged[0]).spent).toBe(true)
+  })
+
+  it('never overwrites local state: records union, settings keep local values', async () => {
+    const aesKey = await deriveBearerAesKey(LINKING_KEY)
+    const secretKey = deriveBackupKey(LINKING_KEY)
+    const {transport} = createRecordingTransport()
+
+    await persistBearer(aesKey, bearerFixture({id: 'remote'}))
+    persistSettings({defaultMint: 'remote.example'})
+    await publishBackup(
+      secretKey,
+      {notes: readEncryptedBearers(), settings: loadSettings()},
+      RELAYS,
+      {transport, createdAt: 1000},
+    )
+
+    // this device already has its own wallet state
+    stubLocalStorage()
+    await persistBearer(
+      aesKey,
+      bearerFixture({id: 'local', url: buildNoteUrl('https://mint.example/w', K1_B, 5_000)}),
+    )
+    persistSettings({defaultMint: 'local.example'})
+
+    const result = await restoreFromNostr(LINKING_KEY, RELAYS, {transport})
+    expect(result.added).toBe(1)
+    expect(
+      readEncryptedBearers()
+        .map((r) => r.id)
+        .sort(),
+    ).toEqual(['local', 'remote'])
+    expect(result.settingsRestored).toBe(false)
+    expect(loadSettings()).toEqual({defaultMint: 'local.example'})
+  })
+
+  it('reports nothing found when the relays hold no backup', async () => {
+    const {transport} = createRecordingTransport()
+    const result = await restoreFromNostr(LINKING_KEY, RELAYS, {transport})
+    expect(result.found).toEqual([])
+    expect(result.added).toBe(0)
+  })
+})