feat: scope NWC storage to wallet owners

src/lnurlcash/nwc.ownership.cases.ts

@@ -0,0 +1,159 @@
+// The NWC wallet service end to end: connection strings and key
+// derivation, the request/response cycle over an in-memory relay (the
+// transport is injected - no network), every method against the
+// conformance mock mint, the legacy NIP-04 path, budget enforcement, and
+// the error paths. Fund-safety focus: budgets can't be exceeded, stale
+// requests never execute, and a settled preimage only ever reveals an
+// already-rotated (burned) note secret.
+
+import {afterEach, beforeEach, describe, expect, it} from 'vitest'
+import {bytesToHex, hexToBytes} from '@noble/hashes/utils.js'
+import {finalizeEvent, getPublicKey} from 'nostr-tools/pure'
+import {encrypt as nip04Encrypt, decrypt as nip04Decrypt} from 'nostr-tools/nip04'
+import {v2 as nip44v2} from 'nostr-tools/nip44'
+import {buildNoteUrl, fetchNoteInfo, noteK1} from 'lnurlcash-kit'
+import {createMockMint} from 'lnurlcash-conformance/mock-mint'
+
+import {
+  NWC_INFO_KIND,
+  NWC_REQUEST_KIND,
+  NWC_RESPONSE_KIND,
+  buildConnectionString,
+  connectionInfoOf,
+  createConnection,
+  deriveNwcWalletKey,
+  migrateLegacyNwcStorage,
+  parseConnectionString,
+  readNwcEnabled,
+  readNwcConnections,
+  startService,
+  writeNwcEnabled,
+  writeNwcConnections,
+} from './nwc'
+import type {NostrEvent, NwcConnectionRecord, NwcServiceDeps, NwcTransport} from './nwc'
+import type {NostrFilter} from './nwc/transport'
+import type {NwcChangeset} from './nwc'
+import type {Bearer} from './types'
+import {ensureSavedKeyOwner, linkingPubKeyHex, saveLinkingKey} from './keys'
+import {requiredValue, stubLocalStorage} from './test-utils'
+
+import {
+  CLIENT_PUBKEY,
+  CLIENT_SECRET,
+  FAST_POLL,
+  LINKING_KEY,
+  OTHER_LINKING_KEY,
+  OTHER_OWNER_ID,
+  OWNER_ID,
+  RELAYS,
+  STRANGER_SECRET,
+  clientRequest,
+  createFakeRelay,
+  deferred,
+  foreignConnectionFixture,
+  methodRequest,
+  nowSeconds,
+  storeForeignConnection,
+  waitFor,
+} from './nwc.testProtocol'
+import {call, makeBearer, mint, readResponse, startTestService} from './nwc.testService'
+describe('service ownership', () => {
+  it('subscribes only current-owner records and leaves foreign budgets untouched', async () => {
+    const current = createConnection(LINKING_KEY, {
+      relays: RELAYS,
+      budget: {maxMsat: 1000, periodMs: 1000},
+      clientSecret: CLIENT_SECRET,
+      now: 0,
+    })
+    const foreign = foreignConnectionFixture({maxMsat: 2000, periodMs: 2000}, 0)
+    storeForeignConnection(foreign.record)
+    const relay = createFakeRelay()
+
+    const service = await startService(LINKING_KEY, {
+      assertCurrentOwner: () => undefined,
+      getBearers: () => [],
+      getDefaultMint: () => null,
+      applyChangeset: () => Promise.resolve(),
+      transport: relay.transport,
+      nowSeconds,
+    })
+
+    expect(service.connections.map((connection) => connection.record)).toEqual([current.record])
+    expect(relay.subscriptionCount()).toBe(1)
+    expect(readNwcConnections(OTHER_OWNER_ID)[0]?.spent.msat).toBe(0)
+    expect(service.connections).not.toContainEqual(foreign)
+    await service.stop()
+  })
+
+  it('ignores foreign records handed in through the records snapshot', async () => {
+    // the injected-records path bypasses storage, so the service's own
+    // owner filter is the only boundary here (stale-ownership probe: a
+    // snapshot from a previous wallet must not be served)
+    const current = createConnection(LINKING_KEY, {
+      relays: RELAYS,
+      budget: {maxMsat: 1000, periodMs: 1000},
+      clientSecret: CLIENT_SECRET,
+      now: 0,
+    })
+    const foreign = foreignConnectionFixture({maxMsat: 2000, periodMs: 2000}, 0)
+    const relay = createFakeRelay()
+
+    const service = await startService(
+      LINKING_KEY,
+      {
+        assertCurrentOwner: () => undefined,
+        getBearers: () => [],
+        getDefaultMint: () => null,
+        applyChangeset: () => Promise.resolve(),
+        transport: relay.transport,
+        nowSeconds,
+      },
+      [current.record, foreign.record],
+    )
+
+    expect(service.connections.map((connection) => connection.record)).toEqual([current.record])
+    expect(relay.subscriptionCount()).toBe(1)
+    // the foreign snapshot record must not be persisted for the new owner
+    expect(readNwcConnections(OWNER_ID)).toEqual([current.record])
+    await service.stop()
+  })
+})
+
+describe('service: info and balance', () => {
+  it('publishes a kind-13194 info event on startup', async () => {
+    const {relay, walletServicePubkey, stop} = await startTestService({})
+    const info = requiredValue(relay.published.find((e) => e.kind === NWC_INFO_KIND))
+    expect(info.pubkey).toBe(walletServicePubkey)
+    expect(info.content).toContain('pay_invoice')
+    expect(info.content).toContain('make_invoice')
+    expect(info.tags).toContainEqual(['encryption', 'nip44_v2 nip04'])
+    await stop()
+  })
+
+  it('answers get_info with the connection identity and method list', async () => {
+    const {relay, walletServicePubkey, stop} = await startTestService({})
+    const response = await call(relay, walletServicePubkey, 'get_info', {})
+    expect(response.error).toBeNull()
+    expect(response.result_type).toBe('get_info')
+    expect(response.result).toMatchObject({
+      alias: 'sattle',
+      pubkey: walletServicePubkey,
+      methods: ['get_info', 'get_balance', 'make_invoice', 'pay_invoice', 'lookup_invoice'],
+    })
+    await stop()
+  })
+
+  it('answers get_balance with the spendable total only', async () => {
+    const m = await mint()
+    const {relay, walletServicePubkey, state, stop} = await startTestService({})
+    state.bearers = [
+      await makeBearer(m, 'aa'.repeat(32), 21_000),
+      await makeBearer(m, 'bb'.repeat(32), 5_000),
+      {...(await makeBearer(m, 'cc'.repeat(32), 99_000)), spent: true},
+    ]
+    const response = await call(relay, walletServicePubkey, 'get_balance', {})
+    expect(response.error).toBeNull()
+    expect(response.result).toEqual({balance: 26_000})
+    await stop()
+  })
+})

src/lnurlcash/nwc.storage.cases.ts

@@ -0,0 +1,173 @@
+// The NWC wallet service end to end: connection strings and key
+// derivation, the request/response cycle over an in-memory relay (the
+// transport is injected - no network), every method against the
+// conformance mock mint, the legacy NIP-04 path, budget enforcement, and
+// the error paths. Fund-safety focus: budgets can't be exceeded, stale
+// requests never execute, and a settled preimage only ever reveals an
+// already-rotated (burned) note secret.
+
+import {afterEach, beforeEach, describe, expect, it} from 'vitest'
+import {bytesToHex, hexToBytes} from '@noble/hashes/utils.js'
+import {finalizeEvent, getPublicKey} from 'nostr-tools/pure'
+import {encrypt as nip04Encrypt, decrypt as nip04Decrypt} from 'nostr-tools/nip04'
+import {v2 as nip44v2} from 'nostr-tools/nip44'
+import {buildNoteUrl, fetchNoteInfo, noteK1} from 'lnurlcash-kit'
+import {createMockMint} from 'lnurlcash-conformance/mock-mint'
+
+import {
+  NWC_INFO_KIND,
+  NWC_REQUEST_KIND,
+  NWC_RESPONSE_KIND,
+  buildConnectionString,
+  connectionInfoOf,
+  createConnection,
+  deriveNwcWalletKey,
+  migrateLegacyNwcStorage,
+  parseConnectionString,
+  readNwcEnabled,
+  readNwcConnections,
+  startService,
+  writeNwcEnabled,
+  writeNwcConnections,
+} from './nwc'
+import type {NostrEvent, NwcConnectionRecord, NwcServiceDeps, NwcTransport} from './nwc'
+import type {NostrFilter} from './nwc/transport'
+import type {NwcChangeset} from './nwc'
+import type {Bearer} from './types'
+import {ensureSavedKeyOwner, linkingPubKeyHex, saveLinkingKey} from './keys'
+import {requiredValue, stubLocalStorage} from './test-utils'
+
+import {
+  CLIENT_PUBKEY,
+  CLIENT_SECRET,
+  FAST_POLL,
+  LINKING_KEY,
+  OTHER_LINKING_KEY,
+  OTHER_OWNER_ID,
+  OWNER_ID,
+  RELAYS,
+  STRANGER_SECRET,
+  clientRequest,
+  createFakeRelay,
+  deferred,
+  foreignConnectionFixture,
+  methodRequest,
+  nowSeconds,
+  storeForeignConnection,
+  waitFor,
+} from './nwc.testProtocol'
+import {call, makeBearer, mint, readResponse, startTestService} from './nwc.testService'
+describe('storage validation', () => {
+  it('drops malformed records instead of throwing', () => {
+    localStorage.setItem(
+      'sattle_nwc_connections',
+      JSON.stringify([
+        {clientPubkey: 'nope'},
+        {
+          version: 1,
+          ownerId: OWNER_ID,
+          clientPubkey: CLIENT_PUBKEY,
+          relays: RELAYS,
+          budget: {maxMsat: 1000, periodMs: 1000},
+          spent: {periodStart: 0, msat: 0},
+          createdAt: 0,
+        },
+      ]),
+    )
+    expect(readNwcConnections(OWNER_ID)).toHaveLength(1)
+    expect(requiredValue(readNwcConnections(OWNER_ID)[0]).clientPubkey).toBe(CLIENT_PUBKEY)
+  })
+
+  it('returns nothing for garbage json', () => {
+    localStorage.setItem('sattle_nwc_connections', '{{{')
+    expect(readNwcConnections(OWNER_ID)).toEqual([])
+  })
+
+  it('returns only strictly parsed records belonging to the requested owner', () => {
+    const current = createConnection(LINKING_KEY, {
+      relays: RELAYS,
+      budget: {maxMsat: 1000, periodMs: 1000},
+      clientSecret: CLIENT_SECRET,
+      now: 10,
+    }).record
+    const foreign = foreignConnectionFixture({maxMsat: 2000, periodMs: 2000}, 20).record
+    const raw: unknown = JSON.parse(localStorage.getItem('sattle_nwc_connections') ?? '[]')
+    if (!Array.isArray(raw)) throw new TypeError('Expected stored NWC records')
+    localStorage.setItem(
+      'sattle_nwc_connections',
+      JSON.stringify([
+        ...raw,
+        foreign,
+        {...current, ownerId: 'malformed'},
+        {
+          clientPubkey: getPublicKey(hexToBytes('33'.repeat(32))),
+          relays: RELAYS,
+          budget: {maxMsat: 3000, periodMs: 3000},
+          spent: {periodStart: 0, msat: 0},
+          createdAt: 30,
+        },
+      ]),
+    )
+
+    expect(readNwcConnections(OWNER_ID)).toEqual([current])
+    expect(readNwcConnections(OTHER_OWNER_ID)).toEqual([foreign])
+  })
+
+  it('adopts ownerless connections and enabled state only after owner proof', async () => {
+    await saveLinkingKey(LINKING_KEY)
+    const saved: unknown = JSON.parse(localStorage.getItem('sattle_linking_key') ?? '{}')
+    if (typeof saved !== 'object' || saved === null) {
+      throw new TypeError('Expected a saved linking-key record')
+    }
+    Reflect.deleteProperty(saved, 'ownerId')
+    Reflect.deleteProperty(saved, 'version')
+    localStorage.setItem('sattle_linking_key', JSON.stringify(saved))
+    localStorage.setItem(
+      'sattle_nwc_connections',
+      JSON.stringify([
+        {
+          clientPubkey: CLIENT_PUBKEY,
+          relays: RELAYS,
+          budget: {maxMsat: 1000, periodMs: 1000},
+          spent: {periodStart: 0, msat: 0},
+          createdAt: 0,
+        },
+      ]),
+    )
+    localStorage.setItem('sattle_nwc_enabled', 'true')
+
+    expect(() => migrateLegacyNwcStorage(LINKING_KEY)).toThrow()
+    expect(readNwcConnections(OWNER_ID)).toEqual([])
+    expect(readNwcEnabled(OWNER_ID)).toBe(false)
+
+    ensureSavedKeyOwner(LINKING_KEY)
+    expect(migrateLegacyNwcStorage(LINKING_KEY)).toEqual({
+      connections: 1,
+      enabled: true,
+    })
+    expect(readNwcConnections(OWNER_ID)).toHaveLength(1)
+    expect(readNwcEnabled(OWNER_ID)).toBe(true)
+    expect(migrateLegacyNwcStorage(LINKING_KEY)).toEqual({
+      connections: 0,
+      enabled: false,
+    })
+  })
+
+  it('does not expose one wallet enabled state to another owner', () => {
+    writeNwcEnabled(OWNER_ID, true)
+
+    expect(readNwcEnabled(OWNER_ID)).toBe(true)
+    expect(readNwcEnabled(OTHER_OWNER_ID)).toBe(false)
+  })
+
+  it('treats malformed owner-bearing enabled records as disabled', () => {
+    for (const value of [
+      {version: 1, ownerId: 'malformed', enabled: true},
+      {version: 2, ownerId: OWNER_ID, enabled: true},
+      {version: 1, ownerId: OWNER_ID, enabled: 'true'},
+    ]) {
+      localStorage.setItem('sattle_nwc_enabled', JSON.stringify(value))
+      expect(readNwcEnabled(OWNER_ID)).toBe(false)
+    }
+  })
+})

src/lnurlcash/storage/nwcConnections.ts

@@ -1,28 +1,34 @@
-// NWC connection persistence: one localStorage record holding every NIP-47
+// NWC connection persistence. Each record and the service-enabled setting
-// connection this wallet serves (see nwc.ts). A record is public metadata
+// belong to one canonical wallet owner, so local residue from another wallet
-// only - the wallet-service key is re-derived from the linking key and the
+// is never served, edited, revoked, or charged. Hostile localStorage input is
-// client pubkey (nwc/connection.ts's deriveNwcWalletKey), and the CLIENT
+// parsed before use; ownerless v0 records remain hidden until an already
-// secret is never stored at all (NIP-47: the wallet service should not
+// proven saved wallet explicitly migrates them.
-// store the secret it generates for the client). The budget spend counter
+
-// lives here so a restart doesn't reset a client's allowance.
+import {linkingPubKeyHex, savedKeyOwnerId} from '../keys'
+import {
+  clearNwcEnabledForOwner,
+  clearUnownedNwcEnabled,
+  readLegacyNwcEnabled,
+  writeNwcEnabled,
+} from './nwcEnabled'
+import {savedKeyOwnerAllows} from './currentOwner'
+import {isWalletOwnerId} from './walletOwner'
 
 export type NwcBudget = {
-  // the most this connection may pay per period, msat
   maxMsat: number
-  // the period length in milliseconds (e.g. 86_400_000 for daily)
   periodMs: number
 }
 
-// spend within the current period; rolls over once periodStart is more
-// than budget.periodMs in the past
 export type NwcBudgetSpend = {
   periodStart: number
   msat: number
 }
 
+const NWC_RECORD_VERSION = 1
+
 export type NwcConnectionRecord = {
-  // the authorized client's pubkey (the pubkey of the client secret that
+  version: typeof NWC_RECORD_VERSION
-  // was handed out in the connection string, once, at creation time)
+  ownerId: string
   clientPubkey: string
   relays: string[]
   budget: NwcBudget
@@ -30,80 +36,192 @@ export type NwcConnectionRecord = {
   createdAt: number
 }
 
+type LegacyNwcConnectionRecord = Omit<NwcConnectionRecord, 'version' | 'ownerId'>
+
+type StoredNwcConnection =
+  {kind: 'owned'; record: NwcConnectionRecord} | {kind: 'legacy'; record: LegacyNwcConnectionRecord}
+
 const NWC_CONNECTIONS_STORAGE_KEY = 'sattle_nwc_connections'
 
-const HEX_64 = /^[0-9a-f]{64}$/i
+const HEX_64 = /^[0-9a-f]{64}$/
 
-// strict shape check, same spirit as passkeySlots.ts: localStorage content
+const isRecord = (value: unknown): value is Record<string, unknown> =>
-// is not trustworthy input, so records are validated before use
+  typeof value === 'object' && value !== null
-const isValidNwcConnectionRecord = (
+
-  record: unknown
+const isPositiveInteger = (value: unknown): value is number =>
-): record is NwcConnectionRecord => {
+  typeof value === 'number' && Number.isSafeInteger(value) && value > 0
-  if (typeof record !== 'object' || record === null) return false
+
-  const r = record as Record<string, unknown>
+const isNonNegativeInteger = (value: unknown): value is number =>
-  const budget = r.budget as Record<string, unknown> | null
+  typeof value === 'number' && Number.isSafeInteger(value) && value >= 0
-  const spent = r.spent as Record<string, unknown> | null
+
-  return (
+const isRelay = (value: unknown): value is string => {
-    typeof r.clientPubkey === 'string' &&
+  if (typeof value !== 'string') return false
-    HEX_64.test(r.clientPubkey) &&
+  try {
-    Array.isArray(r.relays) &&
+    const url = new URL(value)
-    r.relays.length > 0 &&
+    return url.protocol === 'wss:' || url.protocol === 'ws:'
-    r.relays.every(
+  } catch {
-      relay => typeof relay === 'string' && /^wss?:\/\//.test(relay)
+    return false
-    ) &&
+  }
-    typeof budget === 'object' &&
-    budget !== null &&
-    typeof budget.maxMsat === 'number' &&
-    Number.isInteger(budget.maxMsat) &&
-    budget.maxMsat > 0 &&
-    typeof budget.periodMs === 'number' &&
-    budget.periodMs > 0 &&
-    typeof spent === 'object' &&
-    spent !== null &&
-    typeof spent.periodStart === 'number' &&
-    typeof spent.msat === 'number' &&
-    spent.msat >= 0 &&
-    typeof r.createdAt === 'number'
-  )
 }
 
-// malformed entries are dropped, not thrown on - one corrupted record must
+const parseStoredConnection = (value: unknown): StoredNwcConnection | null => {
-// not take the remaining connections down with it
+  if (!isRecord(value)) return null
-export const readNwcConnections = (): NwcConnectionRecord[] => {
+  const {clientPubkey, relays, budget, spent, createdAt} = value
+  if (
+    typeof clientPubkey !== 'string' ||
+    !HEX_64.test(clientPubkey) ||
+    !Array.isArray(relays) ||
+    relays.length === 0 ||
+    !relays.every(isRelay) ||
+    !isRecord(budget) ||
+    !isPositiveInteger(budget.maxMsat) ||
+    !isPositiveInteger(budget.periodMs) ||
+    !isRecord(spent) ||
+    !isNonNegativeInteger(spent.periodStart) ||
+    !isNonNegativeInteger(spent.msat) ||
+    !isNonNegativeInteger(createdAt)
+  ) {
+    return null
+  }
+  const base: LegacyNwcConnectionRecord = {
+    clientPubkey,
+    relays,
+    budget: {maxMsat: budget.maxMsat, periodMs: budget.periodMs},
+    spent: {periodStart: spent.periodStart, msat: spent.msat},
+    createdAt,
+  }
+  if (!Object.hasOwn(value, 'version') && !Object.hasOwn(value, 'ownerId')) {
+    return {kind: 'legacy', record: base}
+  }
+  if (value.version !== NWC_RECORD_VERSION || !isWalletOwnerId(value.ownerId)) {
+    return null
+  }
+  return {
+    kind: 'owned',
+    record: {...base, version: NWC_RECORD_VERSION, ownerId: value.ownerId},
+  }
+}
+
+const readStoredConnections = (): StoredNwcConnection[] => {
   const raw = localStorage.getItem(NWC_CONNECTIONS_STORAGE_KEY)
-  if (!raw) return []
+  if (raw === null) return []
   try {
     const parsed: unknown = JSON.parse(raw)
-    return Array.isArray(parsed)
+    if (!Array.isArray(parsed)) return []
-      ? parsed.filter(isValidNwcConnectionRecord)
+    return parsed
-      : []
+      .map(parseStoredConnection)
+      .filter((entry): entry is StoredNwcConnection => entry !== null)
   } catch {
     return []
   }
 }
 
-export const writeNwcConnections = (
+const storedValue = (entry: StoredNwcConnection): NwcConnectionRecord | LegacyNwcConnectionRecord =>
-  records: NwcConnectionRecord[]
+  entry.record
-): void => {
+
-  localStorage.setItem(NWC_CONNECTIONS_STORAGE_KEY, JSON.stringify(records))
+export const readNwcConnections = (ownerId: unknown): NwcConnectionRecord[] => {
+  if (!isWalletOwnerId(ownerId)) return []
+  return readStoredConnections()
+    .filter(
+      (entry): entry is Extract<StoredNwcConnection, {kind: 'owned'}> =>
+        entry.kind === 'owned' && entry.record.ownerId === ownerId,
+    )
+    .map((entry) => entry.record)
+}
+
+export const writeNwcConnections = (ownerId: unknown, records: NwcConnectionRecord[]): void => {
+  if (!isWalletOwnerId(ownerId) || !savedKeyOwnerAllows(ownerId)) {
+    throw new Error('NWC connections require a valid wallet owner.')
+  }
+  const canonical: NwcConnectionRecord[] = []
+  for (const record of records) {
+    const parsed = parseStoredConnection(record)
+    if (parsed?.kind !== 'owned' || parsed.record.ownerId !== ownerId) {
+      throw new Error('Refusing to write an invalid or foreign NWC connection.')
+    }
+    canonical.push(parsed.record)
+  }
+  const preserved = readStoredConnections()
+    .filter((entry) => entry.kind === 'legacy' || entry.record.ownerId !== ownerId)
+    .map(storedValue)
+  localStorage.setItem(NWC_CONNECTIONS_STORAGE_KEY, JSON.stringify([...preserved, ...canonical]))
 }
 
-// upsert by client pubkey; returns the stored record. Callers serialize
-// read-modify-write cycles themselves (the NWC service serializes per
-// connection through its request queue)
 export const persistNwcConnection = (
-  record: NwcConnectionRecord
+  ownerId: unknown,
+  record: NwcConnectionRecord,
 ): NwcConnectionRecord => {
-  const records = readNwcConnections()
+  if (!isWalletOwnerId(ownerId) || record.ownerId !== ownerId) {
-  const index = records.findIndex(r => r.clientPubkey === record.clientPubkey)
+    throw new Error('NWC connection writes require a valid wallet owner.')
+  }
+  const records = readNwcConnections(ownerId)
+  const index = records.findIndex((stored) => stored.clientPubkey === record.clientPubkey)
   if (index >= 0) records[index] = record
   else records.push(record)
-  writeNwcConnections(records)
+  writeNwcConnections(ownerId, records)
   return record
 }
 
-export const removeNwcConnection = (clientPubkey: string): void => {
+export const removeNwcConnection = (ownerId: unknown, clientPubkey: string): void => {
+  if (!isWalletOwnerId(ownerId)) return
   writeNwcConnections(
-    readNwcConnections().filter(r => r.clientPubkey !== clientPubkey)
+    ownerId,
+    readNwcConnections(ownerId).filter((record) => record.clientPubkey !== clientPubkey),
   )
 }
+
+export type NwcLegacyMigrationResult = {
+  connections: number
+  enabled: boolean
+}
+
+export const migrateLegacyNwcStorage = (linkingKey: Uint8Array): NwcLegacyMigrationResult => {
+  const ownerId = linkingPubKeyHex(linkingKey)
+  if (savedKeyOwnerId() !== ownerId) {
+    throw new Error('Legacy NWC migration requires a proven saved wallet owner.')
+  }
+
+  const stored = readStoredConnections()
+  let connections = 0
+  const migrated = stored.map((entry) => {
+    if (entry.kind === 'owned') return entry.record
+    connections += 1
+    return {
+      ...entry.record,
+      version: NWC_RECORD_VERSION,
+      ownerId,
+    } satisfies NwcConnectionRecord
+  })
+  if (connections > 0) {
+    localStorage.setItem(NWC_CONNECTIONS_STORAGE_KEY, JSON.stringify(migrated))
+  }
+
+  const legacyEnabled = readLegacyNwcEnabled()
+  if (legacyEnabled !== null) writeNwcEnabled(ownerId, legacyEnabled)
+  return {connections, enabled: legacyEnabled !== null}
+}
+
+const persistStoredConnections = (entries: StoredNwcConnection[]): void => {
+  if (entries.length === 0) {
+    localStorage.removeItem(NWC_CONNECTIONS_STORAGE_KEY)
+    return
+  }
+  localStorage.setItem(NWC_CONNECTIONS_STORAGE_KEY, JSON.stringify(entries.map(storedValue)))
+}
+
+export const clearNwcStorageForOwner = (ownerId: unknown): void => {
+  if (!isWalletOwnerId(ownerId) || !savedKeyOwnerAllows(ownerId)) {
+    throw new Error('NWC teardown requires a valid wallet owner.')
+  }
+  persistStoredConnections(
+    readStoredConnections().filter(
+      (entry) => entry.kind === 'legacy' || entry.record.ownerId !== ownerId,
+    ),
+  )
+  clearNwcEnabledForOwner(ownerId)
+}
+
+export const clearUnownedNwcStorage = (): void => {
+  persistStoredConnections(readStoredConnections().filter((entry) => entry.kind === 'owned'))
+  clearUnownedNwcEnabled()
+}

src/lnurlcash/storage/nwcEnabled.ts

@@ -0,0 +1,87 @@
+// NWC service-enabled persistence: one owner-bearing record for whether the
+// wallet service should run. Split from nwcConnections.ts (size ceiling) -
+// the enabled flag and the connection records are independent storage keys
+// with the same ownership rules: hostile input is parsed before use, and a
+// legacy global 'true'/'false' string counts as ownerless residue until an
+// already proven saved wallet migrates it.
+
+import {isWalletOwnerId} from './walletOwner'
+import {savedKeyOwnerAllows} from './currentOwner'
+
+const NWC_ENABLED_STORAGE_KEY = 'sattle_nwc_enabled'
+const NWC_ENABLED_VERSION = 1
+
+type NwcEnabledRecord = {
+  version: typeof NWC_ENABLED_VERSION
+  ownerId: string
+  enabled: boolean
+}
+
+const isRecord = (value: unknown): value is Record<string, unknown> =>
+  typeof value === 'object' && value !== null
+
+const readNwcEnabledRecord = (): NwcEnabledRecord | null => {
+  const raw = localStorage.getItem(NWC_ENABLED_STORAGE_KEY)
+  if (raw === null) return null
+  try {
+    const parsed: unknown = JSON.parse(raw)
+    if (
+      !isRecord(parsed) ||
+      parsed.version !== NWC_ENABLED_VERSION ||
+      !isWalletOwnerId(parsed.ownerId) ||
+      typeof parsed.enabled !== 'boolean'
+    ) {
+      return null
+    }
+    return {
+      version: NWC_ENABLED_VERSION,
+      ownerId: parsed.ownerId,
+      enabled: parsed.enabled,
+    }
+  } catch {
+    return null
+  }
+}
+
+export const readNwcEnabled = (ownerId: unknown): boolean => {
+  if (!isWalletOwnerId(ownerId)) return false
+  const record = readNwcEnabledRecord()
+  return record?.ownerId === ownerId && record.enabled
+}
+
+export const writeNwcEnabled = (ownerId: unknown, enabled: boolean): void => {
+  if (!isWalletOwnerId(ownerId) || !savedKeyOwnerAllows(ownerId)) {
+    throw new Error('NWC enabled state requires a valid wallet owner.')
+  }
+  localStorage.setItem(
+    NWC_ENABLED_STORAGE_KEY,
+    JSON.stringify({version: NWC_ENABLED_VERSION, ownerId, enabled}),
+  )
+}
+
+// the pre-owner storage form was a bare 'true'/'false' string - returns it
+// when present so legacy migration can re-home the value under the proven
+// owner, null for anything else (absent, junk, or an owned envelope)
+export const readLegacyNwcEnabled = (): boolean | null => {
+  const raw = localStorage.getItem(NWC_ENABLED_STORAGE_KEY)
+  if (raw === 'true') return true
+  if (raw === 'false') return false
+  return null
+}
+
+// teardown of one owner's enabled state - any other owner's record (or a
+// legacy string) is left exactly as found
+export const clearNwcEnabledForOwner = (ownerId: unknown): void => {
+  if (!isWalletOwnerId(ownerId)) return
+  if (readNwcEnabledRecord()?.ownerId === ownerId) {
+    localStorage.removeItem(NWC_ENABLED_STORAGE_KEY)
+  }
+}
+
+// install-time residue sweep: only the legacy string form is unowned; an
+// owned envelope stays (it is inert for every other owner)
+export const clearUnownedNwcEnabled = (): void => {
+  if (readLegacyNwcEnabled() !== null) {
+    localStorage.removeItem(NWC_ENABLED_STORAGE_KEY)
+  }
+}