refactor(nostr): route signing + encryption through a Signer abstraction

Introduce a Signer interface (signEvent / nip44Encrypt / nip44Decrypt +
sync pubkey) with an in-process LocalSigner backed by an nsec, and route
every signing/encryption call site through it. Behaviour is unchanged —
LocalSigner wraps the same MachineIdentity the code used directly before.

This is Phase A of the bunker migration (aiolabs/bitspire#52): it puts the
seam in place so Phase B can drop in a NIP-46 BunkerSigner at the bootstrap
without touching any call site. The whole chain becomes async (the bunker
path is a relay round-trip; LocalSigner resolves immediately).

Sites moved onto the signer:
- packages/nostr-client: createSignedEvent / createAuthEvent (now async),
  NostrClient config (signer not identity), AUTH challenge handler.
- packages/lnbits: LnbitsClient.initialize(nostr, signer); kind-21000 RPC
  encrypt + sign + reply-decrypt; handleReply is now async (event-id dedup
  still runs synchronously before the awaited decrypt, so replay safety and
  per-subscription hash dedup are preserved).
- apps/machine: lightning.ts builds a LocalSigner and exposes it on
  LightningServices; operator-config / operator-fees / availability beacon /
  maintenance beacon / fund-atm all sign + encrypt via the signer.

NIP-42 auth (kind 22242) is included — under the bunker it must be in the
spire policy (aiolabs/spirekeeper#26, already merged).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/lnbits/src/__tests__/client.test.ts

@@ -17,6 +17,7 @@ import {
 } from 'nostr-tools'
 import {
   encryptContentV2,
+  LocalSigner,
   type MachineIdentity,
   type NostrClient,
 } from '@bitSpire/nostr-client'
@@ -152,7 +153,7 @@ describe('isAuthenticServerEvent', () => {
 describe('LnbitsClient.handleReply wiring', () => {
   function makeMockNostr(): {
     nostr: NostrClient
-    triggerEvent: (ev: NostrEvent) => void
+    triggerEvent: (ev: NostrEvent) => Promise<void>
   } {
     let captured: ((ev: NostrEvent) => void) | null = null
     const nostr = {
@@ -168,9 +169,12 @@ describe('LnbitsClient.handleReply wiring', () => {
     } as unknown as NostrClient
     return {
       nostr,
-      triggerEvent: (ev) => {
+      // `handleReply` is async (the signer's nip44Decrypt is a promise),
+      // so flush microtasks + a macrotask tick before the caller asserts.
+      triggerEvent: async (ev) => {
         if (!captured) throw new Error('handleReply not wired yet')
         captured(ev)
+        await new Promise<void>((resolve) => setTimeout(resolve, 0))
       },
     }
   }
@@ -188,7 +192,7 @@ describe('LnbitsClient.handleReply wiring', () => {
     client: LnbitsClient
     serverIdentity: MachineIdentity
     recipientIdentity: MachineIdentity
-    triggerEvent: (ev: NostrEvent) => void
+    triggerEvent: (ev: NostrEvent) => Promise<void>
   } {
     const serverIdentity = makeIdentity()
     const recipientIdentity = makeIdentity()
@@ -197,11 +201,11 @@ describe('LnbitsClient.handleReply wiring', () => {
       serverPubkey: serverIdentity.publicKey,
       relays: ['ws://test/'],
     })
-    client.initialize(nostr, recipientIdentity)
+    client.initialize(nostr, new LocalSigner(recipientIdentity))
     return { client, serverIdentity, recipientIdentity, triggerEvent }
   }
 
-  it('drops a forged event without resolving any pending RPC', () => {
+  it('drops a forged event without resolving any pending RPC', async () => {
     const { client, serverIdentity, triggerEvent } = setupClient()
 
     // Pre-register a pending entry as `sendRpc` would have.
@@ -233,7 +237,7 @@ describe('LnbitsClient.handleReply wiring', () => {
       attackerKey,
     )
 
-    triggerEvent(forged)
+    await triggerEvent(forged)
 
     expect(resolveCalls).toBe(0)
     expect(rejectCalls).toBe(0)
@@ -241,7 +245,7 @@ describe('LnbitsClient.handleReply wiring', () => {
     expect((client as any).pending.has('req-forged')).toBe(true)
   })
 
-  it('processes a legitimate server-signed reply (positive sanity)', () => {
+  it('processes a legitimate server-signed reply (positive sanity)', async () => {
     const { client, serverIdentity, recipientIdentity, triggerEvent } =
       setupClient()
 
@@ -277,7 +281,7 @@ describe('LnbitsClient.handleReply wiring', () => {
       serverIdentity.privateKey,
     )
 
-    triggerEvent(reply)
+    await triggerEvent(reply)
 
     expect(resolved).toMatchObject({
       status: 'OK',
@@ -290,7 +294,7 @@ describe('LnbitsClient.handleReply wiring', () => {
     // fine, we only need to assert resolve fired with the right payload.
   })
 
-  it('does not poison the seenEventIds cache with a forged event', () => {
+  it('does not poison the seenEventIds cache with a forged event', async () => {
     // This is the test scenario where the #49 guard's contribution
     // actually shows up: ev.id is the dedup key for the client-global
     // exact-replay cache. WITHOUT the guard, an attacker could publish
@@ -320,7 +324,7 @@ describe('LnbitsClient.handleReply wiring', () => {
       attackerKey,
     )
 
-    triggerEvent(forged)
+    await triggerEvent(forged)
 
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     expect((client as any).seenEventIds.size).toBe(0)
@@ -345,7 +349,7 @@ describe('LnbitsClient.handleReply wiring', () => {
 describe('LnbitsClient subscribe-payments dedup (#50)', () => {
   function makeMockNostr(): {
     nostr: NostrClient
-    triggerEvent: (ev: NostrEvent) => void
+    triggerEvent: (ev: NostrEvent) => Promise<void>
   } {
     let captured: ((ev: NostrEvent) => void) | null = null
     const nostr = {
@@ -361,9 +365,12 @@ describe('LnbitsClient subscribe-payments dedup (#50)', () => {
     } as unknown as NostrClient
     return {
       nostr,
-      triggerEvent: (ev) => {
+      // `handleReply` is async (the signer's nip44Decrypt is a promise),
+      // so flush microtasks + a macrotask tick before the caller asserts.
+      triggerEvent: async (ev) => {
         if (!captured) throw new Error('handleReply not wired yet')
         captured(ev)
+        await new Promise<void>((resolve) => setTimeout(resolve, 0))
       },
     }
   }
@@ -436,7 +443,7 @@ describe('LnbitsClient subscribe-payments dedup (#50)', () => {
     )
   }
 
-  it('fires onPush once when the same event is injected twice (exact-replay dedup)', () => {
+  it('fires onPush once when the same event is injected twice (exact-replay dedup)', async () => {
     const serverIdentity = makeIdentity()
     const recipientIdentity = makeIdentity()
     const { nostr, triggerEvent } = makeMockNostr()
@@ -444,7 +451,7 @@ describe('LnbitsClient subscribe-payments dedup (#50)', () => {
       serverPubkey: serverIdentity.publicKey,
       relays: ['ws://test/'],
     })
-    client.initialize(nostr, recipientIdentity)
+    client.initialize(nostr, new LocalSigner(recipientIdentity))
 
     const { received } = preregisterSub(client, 'sub-1')
 
@@ -455,14 +462,14 @@ describe('LnbitsClient subscribe-payments dedup (#50)', () => {
       paymentHash: 'hash-aaa',
     })
     // Same bytes both times — same ev.id, same payment_hash.
-    triggerEvent(ev)
-    triggerEvent(ev)
+    await triggerEvent(ev)
+    await triggerEvent(ev)
 
     expect(received).toHaveLength(1)
     expect(received[0]!.payment_hash).toBe('hash-aaa')
   })
 
-  it('fires onPush once when two distinct ev.ids carry the same payment_hash', () => {
+  it('fires onPush once when two distinct ev.ids carry the same payment_hash', async () => {
     const serverIdentity = makeIdentity()
     const recipientIdentity = makeIdentity()
     const { nostr, triggerEvent } = makeMockNostr()
@@ -470,7 +477,7 @@ describe('LnbitsClient subscribe-payments dedup (#50)', () => {
       serverPubkey: serverIdentity.publicKey,
       relays: ['ws://test/'],
     })
-    client.initialize(nostr, recipientIdentity)
+    client.initialize(nostr, new LocalSigner(recipientIdentity))
 
     const { received } = preregisterSub(client, 'sub-1')
 
@@ -493,14 +500,14 @@ describe('LnbitsClient subscribe-payments dedup (#50)', () => {
       createdAt: now + 1,
     })
     expect(ev1.id).not.toBe(ev2.id) // sanity: ev.id dedup would NOT catch this
-    triggerEvent(ev1)
-    triggerEvent(ev2)
+    await triggerEvent(ev1)
+    await triggerEvent(ev2)
 
     expect(received).toHaveLength(1)
     expect(received[0]!.payment_hash).toBe('hash-bbb')
   })
 
-  it('fires onPush for each distinct payment_hash (negative dedup case)', () => {
+  it('fires onPush for each distinct payment_hash (negative dedup case)', async () => {
     const serverIdentity = makeIdentity()
     const recipientIdentity = makeIdentity()
     const { nostr, triggerEvent } = makeMockNostr()
@@ -508,7 +515,7 @@ describe('LnbitsClient subscribe-payments dedup (#50)', () => {
       serverPubkey: serverIdentity.publicKey,
       relays: ['ws://test/'],
     })
-    client.initialize(nostr, recipientIdentity)
+    client.initialize(nostr, new LocalSigner(recipientIdentity))
 
     const { received } = preregisterSub(client, 'sub-1')
 
@@ -525,14 +532,14 @@ describe('LnbitsClient subscribe-payments dedup (#50)', () => {
       paymentHash: 'hash-2',
       createdAt: Math.floor(Date.now() / 1000) + 2,
     })
-    triggerEvent(ev1)
-    triggerEvent(ev2)
+    await triggerEvent(ev1)
+    await triggerEvent(ev2)
 
     expect(received).toHaveLength(2)
     expect(received.map((p) => p.payment_hash)).toEqual(['hash-1', 'hash-2'])
   })
 
-  it('keeps dedup state per-subscription (one sub seeing a hash does not silence another)', () => {
+  it('keeps dedup state per-subscription (one sub seeing a hash does not silence another)', async () => {
     const serverIdentity = makeIdentity()
     const recipientIdentity = makeIdentity()
     const { nostr, triggerEvent } = makeMockNostr()
@@ -540,7 +547,7 @@ describe('LnbitsClient subscribe-payments dedup (#50)', () => {
       serverPubkey: serverIdentity.publicKey,
       relays: ['ws://test/'],
     })
-    client.initialize(nostr, recipientIdentity)
+    client.initialize(nostr, new LocalSigner(recipientIdentity))
 
     const a = preregisterSub(client, 'sub-A')
     const b = preregisterSub(client, 'sub-B')
@@ -561,8 +568,8 @@ describe('LnbitsClient subscribe-payments dedup (#50)', () => {
       paymentHash: 'hash-shared',
       createdAt: Math.floor(Date.now() / 1000) + 1,
     })
-    triggerEvent(evA)
-    triggerEvent(evB)
+    await triggerEvent(evA)
+    await triggerEvent(evB)
 
     // Each subscription sees its own push exactly once.
     expect(a.received).toHaveLength(1)

packages/lnbits/src/client.ts

@@ -22,12 +22,10 @@
 
 import {
   type NostrClient,
-  type MachineIdentity,
+  type Signer,
   type Event as NostrEvent,
-  encryptContentV2,
-  decryptContentV2,
 } from '@bitSpire/nostr-client'
-import { finalizeEvent, verifyEvent } from 'nostr-tools'
+import { verifyEvent } from 'nostr-tools'
 
 import type {
   LnbitsConfig,
@@ -121,7 +119,7 @@ const SEEN_PAYMENT_HASHES_MAX = 500
 export class LnbitsClient {
   private readonly config: Required<LnbitsConfig>
   private nostr: NostrClient | null = null
-  private identity: MachineIdentity | null = null
+  private signer: Signer | null = null
   private requestCounter = 0
   private readonly pending = new Map<
     string,
@@ -150,9 +148,9 @@ export class LnbitsClient {
     }
   }
 
-  initialize(nostr: NostrClient, identity: MachineIdentity): void {
+  initialize(nostr: NostrClient, signer: Signer): void {
     this.nostr = nostr
-    this.identity = identity
+    this.signer = signer
     this.startReplyListener()
   }
 
@@ -240,7 +238,7 @@ export class LnbitsClient {
     onPush: PaymentPushCallback,
     onClose?: SubscriptionCloseCallback,
   ): Promise<string> {
-    if (!this.nostr || !this.identity) {
+    if (!this.nostr || !this.signer) {
       throw new Error('LnbitsClient.subscribePayments: client not initialized')
     }
     const requestId = this.nextRequestId('sub')
@@ -431,7 +429,7 @@ export class LnbitsClient {
       requestId?: string
     },
   ): Promise<T> {
-    if (!this.nostr || !this.identity) {
+    if (!this.nostr || !this.signer) {
       throw new Error(`LnbitsClient.${rpcName}: client not initialized`)
     }
     const requestId = args.requestId ?? this.nextRequestId(rpcName)
@@ -444,10 +442,10 @@ export class LnbitsClient {
     if (args.query !== undefined) request.query = args.query as Record<string, unknown>
 
     const plaintext = JSON.stringify(request)
-    const encrypted = encryptContentV2(this.identity, this.config.serverPubkey, plaintext)
+    const encrypted = await this.signer.nip44Encrypt(this.config.serverPubkey, plaintext)
 
-    // Build + sign the kind-21000 event ourselves. The server reads our
-    // pubkey directly off the signature, so there's no separate
+    // Build + sign the kind-21000 event via the signer. The server reads
+    // our pubkey directly off the signature, so there's no separate
     // authIdentifier in the envelope (unlike LightningPubClient).
     //
     // NIP-40 expiration: 5 minutes past now. Defence-in-depth at the
@@ -457,18 +455,15 @@ export class LnbitsClient {
     // attacker can't bypass this by stripping the tag; the tag just
     // lets the relay short-circuit earlier.
     const now = Math.floor(Date.now() / 1000)
-    const event = finalizeEvent(
-      {
-        kind: LNBITS_KIND_RPC,
-        content: encrypted,
-        tags: [
-          ['p', this.config.serverPubkey],
-          ['expiration', String(now + 300)],
-        ],
-        created_at: now,
-      },
-      this.identity.privateKey,
-    )
+    const event = await this.signer.signEvent({
+      kind: LNBITS_KIND_RPC,
+      content: encrypted,
+      tags: [
+        ['p', this.config.serverPubkey],
+        ['expiration', String(now + 300)],
+      ],
+      created_at: now,
+    })
 
     // The pending entry MUST be registered before publish so we don't race
     // an extremely fast reply.
@@ -508,8 +503,8 @@ export class LnbitsClient {
    * based on `request_id` and `subscription_id`.
    */
   private startReplyListener(): void {
-    if (!this.nostr || !this.identity) return
-    const myPubkey = this.identity.publicKey
+    if (!this.nostr || !this.signer) return
+    const myPubkey = this.signer.pubkey
     const since = Math.floor(Date.now() / 1000) - 5
 
     this.relaySubIdForReplies = this.nostr.subscribe(
@@ -522,25 +517,28 @@ export class LnbitsClient {
         },
       ],
       {
-        onEvent: (ev: NostrEvent) => this.handleReply(ev),
+        onEvent: (ev: NostrEvent) => void this.handleReply(ev),
       },
     )
   }
 
-  private handleReply(ev: NostrEvent): void {
-    if (!this.identity) return
+  private async handleReply(ev: NostrEvent): Promise<void> {
+    const signer = this.signer
+    if (!signer) return
     if (!isAuthenticServerEvent(ev, this.config.serverPubkey)) return
     // Exact-replay dedup. Skip if we've already processed this event id.
     // Safe to trust `ev.id` here because `isAuthenticServerEvent` just
     // Schnorr-verified the event (`verifyEvent` recomputes the id and
     // confirms it matches the signed pubkey + body). Without that
     // guarantee an attacker could pre-poison this set with chosen ids.
+    // Runs before the async decrypt so concurrent re-deliveries of the
+    // same id still dedup synchronously.
     if (this.seenEventIds.has(ev.id)) return
     this.recordSeenEventId(ev.id)
 
     let plaintext: string
     try {
-      plaintext = decryptContentV2(this.identity, this.config.serverPubkey, ev.content)
+      plaintext = await signer.nip44Decrypt(this.config.serverPubkey, ev.content)
     } catch {
       return // not our peer or wrong key
     }