feat(machine): resolve signer from spire seed / bunker binding at bootstrap

New signer-resolver.ts turns the ATM's pairing state into a Signer:
 - seed present, fingerprint differs from stored binding → pair: generate a
   transport key, redeem the one-shot connect secret, persist the binding,
   reset the bootstrap gate (re-publish hello to the new operator, #56);
 - seed matches binding, or binding-only → resume (no re-redeem);
 - neither → ephemeral LocalSigner (dev) or throw (strict/prod).

lightning.ts drops the atmPrivateKey plumbing and calls resolveSigner; the
Phase-A Signer seam means nothing downstream changes. App.vue's maintenance
beacon resolves the same way (best-effort, skips if unpaired).

Part of Phase C, aiolabs/bitspire#52.

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

apps/machine/src/App.vue

@@ -51,14 +51,13 @@ onMounted(async () => {
     atmStore.initError = 'maintenance'
     // Publish maintenance beacon — minimal Nostr connection only (no Lightning.Pub)
     try {
-      const { NostrClient, LocalSigner, loadIdentityFromHex, createSignedEvent } = await import(
-        '@bitSpire/nostr-client'
-      )
-      const secrets = isElectron ? await window.electronAPI?.getAtmSecrets() : null
-      const privKey = secrets?.atmPrivateKey || import.meta.env.VITE_ATM_PRIVATE_KEY
+      const { NostrClient, createSignedEvent } = await import('@bitSpire/nostr-client')
+      const { resolveSigner } = await import('@/services/signer-resolver')
       const relayUrl = config?.relayUrl || import.meta.env.VITE_RELAY_URL
-      if (privKey && relayUrl) {
-        const signer = new LocalSigner(loadIdentityFromHex(privKey))
+      // Best-effort: resolve a signer (bunker resume / pairing, or dev nsec).
+      // If the ATM isn't paired yet, skip the beacon rather than fail the screen.
+      const signer = await resolveSigner({ allowEphemeral: true }).catch(() => null)
+      if (signer && relayUrl) {
         const client = new NostrClient({ relays: [{ url: relayUrl }], signer })
         await client.connect()
         const publishBeacon = async () => {

apps/machine/src/services/lightning.ts

@@ -12,14 +12,8 @@
  * the customer's invoice.
  */
 
-import {
-  NostrClient,
-  LocalSigner,
-  generateIdentity,
-  loadIdentityFromHex,
-  type Signer,
-  type MachineIdentity,
-} from '@bitSpire/nostr-client'
+import { NostrClient, type Signer } from '@bitSpire/nostr-client'
+import { resolveSigner } from './signer-resolver.js'
 import { LnbitsClient } from '@bitSpire/lnbits'
 import { CLINKClient } from '@bitSpire/clink'
 import type { OfferRequest, ManagementRequest, ManagementResponse } from '@bitSpire/clink'
@@ -39,14 +33,12 @@ const isElectron = typeof window !== 'undefined' && window.electronAPI !== undef
  *
  * Environment variables:
  * - VITE_RELAY_URL: Nostr relay WebSocket URL
- * - VITE_LIGHTNING_PUB_PUBKEY: Lightning.Pub's Nostr pubkey (hex or npub)
- * - VITE_LIGHTNING_PUB_API_URL: Lightning.Pub HTTP API URL
- * - VITE_ATM_PRIVATE_KEY: ATM's Nostr private key (hex or nsec)   // pragma: allowlist secret
- * - VITE_ADMIN_TOKEN: Lightning.Pub admin token (dev only)
+ * - VITE_LNBITS_SERVER_PUBKEY: LNbits nostr-transport server pubkey (hex)
+ * - VITE_SPIRE_SEED: spire pairing seed (NIP-46 bunker); see signer-resolver.ts
+ * - VITE_OPERATOR_PUBKEYS: comma-separated operator pubkeys (hex)
  */
 interface LightningConfig {
   relayUrl: string
-  atmPrivateKey: string
   appId: string
   operatorPubkeys: string[]
   /** LNbits nostr-transport server pubkey (hex, 64 chars). */
@@ -63,7 +55,6 @@ interface LightningConfig {
 async function loadLightningConfig(): Promise<LightningConfig> {
   const defaults: LightningConfig = {
     relayUrl: 'ws://localhost:7777',
-    atmPrivateKey: '',
     appId: '30270e761f2e30b1737f34ce661df45f521352b408b8ed18fcc09f3f0dec5097', // bitSpire ATM app ID
     operatorPubkeys: [],
     lnbitsServerPubkey: '',
@@ -72,10 +63,8 @@ async function loadLightningConfig(): Promise<LightningConfig> {
   if (isElectron && window.electronAPI) {
     try {
       const rc = await window.electronAPI.getConfig()
-      const sec = await window.electronAPI.getAtmSecrets()
       return {
         relayUrl: rc.relayUrl || defaults.relayUrl,
-        atmPrivateKey: sec.atmPrivateKey || defaults.atmPrivateKey,
         appId: rc.appId || defaults.appId,
         operatorPubkeys: rc.operatorPubkeys
           ? rc.operatorPubkeys
@@ -92,7 +81,6 @@ async function loadLightningConfig(): Promise<LightningConfig> {
 
   return {
     relayUrl: import.meta.env.VITE_RELAY_URL || defaults.relayUrl,
-    atmPrivateKey: import.meta.env.VITE_ATM_PRIVATE_KEY || defaults.atmPrivateKey,
     appId: import.meta.env.VITE_APP_ID || defaults.appId,
     lnbitsServerPubkey:
       (import.meta.env.VITE_LNBITS_SERVER_PUBKEY as string | undefined) ||
@@ -416,15 +404,14 @@ export async function initializeLightningServices(options?: {
   console.log('[Lightning] Relay URL:', CONFIG.relayUrl)
   console.log('[Lightning] LNbits server pubkey:', CONFIG.lnbitsServerPubkey || '(not configured)')
 
-  // Strict mode: validate config is production-ready (no localhost, no ephemeral identity)
+  // Strict mode: validate config is production-ready (no localhost). The
+  // signing-identity check (a bunker pairing must exist) is enforced by
+  // resolveSigner below via allowEphemeral=false.
   if (options?.strict) {
     const errors: string[] = []
     if (/localhost|127\.0\.0\.1/.test(CONFIG.relayUrl)) {
       errors.push('VITE_RELAY_URL contains localhost')
     }
-    if (!CONFIG.atmPrivateKey) {
-      errors.push('VITE_ATM_PRIVATE_KEY is not set (ephemeral identity not allowed in production)')
-    }
     if (!CONFIG.lnbitsServerPubkey) {
       errors.push('VITE_LNBITS_SERVER_PUBKEY is not set')
     }
@@ -441,22 +428,13 @@ export async function initializeLightningServices(options?: {
     )
   }
 
-  // Load or generate ATM identity
-  let identity: MachineIdentity
-  if (CONFIG.atmPrivateKey) {
-    identity = loadIdentityFromHex(CONFIG.atmPrivateKey)
-    console.log('[Lightning] Loaded ATM identity from config')
-  } else {
-    identity = generateIdentity()
-    console.warn('[Lightning] No VITE_ATM_PRIVATE_KEY configured - generated ephemeral identity')
-    console.warn('[Lightning] Set VITE_ATM_PRIVATE_KEY for persistent identity across restarts')
-  }
-  console.log('[Lightning] ATM pubkey:', identity.publicKey)
-
-  // Wrap the identity in a signer. Phase A always uses LocalSigner (in-process
-  // nsec); Phase B swaps in a BunkerSigner here without touching the call
-  // sites below. See aiolabs/bitspire#52.
-  const signer: Signer = new LocalSigner(identity)
+  // Resolve the signing identity. In production this is a BunkerSigner over
+  // NIP-46 (the ATM holds only a transport key; the operator's nsecbunkerd
+  // holds the signing key); in dev it falls back to an in-process LocalSigner.
+  // The Phase-A Signer seam means nothing downstream changes. See
+  // aiolabs/bitspire#52.
+  const signer: Signer = await resolveSigner({ allowEphemeral: !options?.strict })
+  console.log('[Lightning] ATM pubkey:', signer.pubkey)
 
   // Create Nostr client
   const nostrClient = new NostrClient({
@@ -491,7 +469,7 @@ export async function initializeLightningServices(options?: {
   // commands; it has no Lightning.Pub dependency.
   const clink = new CLINKClient({
     nostrClient,
-    identity,
+    signer,
     operatorPubkey: CONFIG.operatorPubkeys,
     relays: [CONFIG.relayUrl],
   })
@@ -581,7 +559,6 @@ export async function initializeLightningServices(options?: {
   }
 
   const atmServices = createATMServices(
-    identity,
     (preimage) => {
       if (paymentReceivedCallback) {
         paymentReceivedCallback(preimage)
@@ -624,7 +601,6 @@ export async function initializeLightningServices(options?: {
  * Create ATMServices implementation using the LNbits nostr-transport.
  */
 function createATMServices(
-  _identity: MachineIdentity,
   onPaymentSuccess: (preimage: string) => void,
   lnbits: LnbitsClient,
   lnbitsWalletId: string,

apps/machine/src/services/signer-resolver.ts

@@ -0,0 +1,116 @@
+/**
+ * Signer resolution — turns the ATM's pairing state into a live `Signer`.
+ *
+ * Three outcomes, in priority order (aiolabs/bitspire#52, model A1):
+ *  1. A seed is present whose fingerprint differs from the stored binding
+ *     (first pair or re-pair) → generate a fresh NIP-46 transport key, redeem
+ *     the one-shot connect secret, persist the binding, and reset the
+ *     bootstrap gate so the (possibly new) operator gets a hello-event (#56).
+ *  2. A seed is present matching the stored binding, OR no seed but a stored
+ *     binding exists → resume the bunker session with the persisted transport
+ *     key (no re-redeem — the binding is server-persistent).
+ *  3. Neither → ephemeral LocalSigner, dev only. In strict (production) mode
+ *     this throws instead: no pairing means no signing identity.
+ *
+ * Runs in the renderer (where the relay I/O lives); state.db reads/writes go
+ * through the one-shot get-atm-secrets channel + the binding IPC handlers.
+ */
+
+import {
+  LocalSigner,
+  connectNewSeed,
+  resumeFromBinding,
+  generateClientTransportKey,
+  generateIdentity,
+  loadIdentityFromHex,
+  parseSpireSeed,
+  seedFingerprint,
+  type Signer,
+} from '@bitSpire/nostr-client'
+import type { BunkerBindingRecord } from '@/types/electron'
+
+const isElectron = typeof window !== 'undefined' && window.electronAPI !== undefined
+
+export interface ResolveSignerOptions {
+  /** Allow an ephemeral LocalSigner when no seed/binding exists (dev only). */
+  allowEphemeral: boolean
+}
+
+interface PairingState {
+  spireSeed: string
+  binding: BunkerBindingRecord | null
+}
+
+/** Gather the seed + persisted binding from Electron, or env in browser dev. */
+async function loadPairingState(): Promise<PairingState> {
+  if (isElectron && window.electronAPI) {
+    const secrets = await window.electronAPI.getAtmSecrets()
+    return { spireSeed: secrets.spireSeed || '', binding: secrets.bunkerBinding ?? null }
+  }
+  return { spireSeed: (import.meta.env.VITE_SPIRE_SEED as string | undefined) || '', binding: null }
+}
+
+export async function resolveSigner(opts: ResolveSignerOptions): Promise<Signer> {
+  const { spireSeed, binding } = await loadPairingState()
+
+  if (spireSeed) {
+    const seed = parseSpireSeed(spireSeed)
+    const fingerprint = seedFingerprint(spireSeed)
+
+    if (binding && binding.seedFingerprint === fingerprint) {
+      console.log('[Signer] Resuming bunker session for spire', seed.spirePubkey)
+      return resumeFromBinding({
+        clientSecretHex: binding.clientSecretHex,
+        spirePubkey: binding.spirePubkey,
+        bunkerUrl: binding.bunkerUrl,
+      })
+    }
+
+    // First pair or re-pair: redeem the one-shot connect secret.
+    console.log('[Signer] Pairing to bunker for spire', seed.spirePubkey)
+    const transport = generateClientTransportKey()
+    const signer = await connectNewSeed({
+      spirePubkey: seed.spirePubkey,
+      bunkerUrl: seed.bunkerUrl,
+      clientSecretHex: transport.secretHex,
+    })
+    if (isElectron && window.electronAPI) {
+      await window.electronAPI.saveBunkerBinding({
+        clientSecretHex: transport.secretHex,
+        spirePubkey: seed.spirePubkey,
+        bunkerUrl: seed.bunkerUrl,
+        seedFingerprint: fingerprint,
+        pairedAt: Math.floor(Date.now() / 1000),
+      })
+      // Re-pair → re-publish the cassette-state hello to the new operator (#56).
+      await window.electronAPI.resetBootstrapGate()
+    }
+    return signer
+  }
+
+  // No seed in this boot but a binding survives → resume.
+  if (binding) {
+    console.log('[Signer] Resuming bunker session from stored binding (no seed this boot)')
+    return resumeFromBinding({
+      clientSecretHex: binding.clientSecretHex,
+      spirePubkey: binding.spirePubkey,
+      bunkerUrl: binding.bunkerUrl,
+    })
+  }
+
+  if (opts.allowEphemeral) {
+    // Dev-only: a hex key gives a stable dev identity; otherwise ephemeral.
+    const devKey = !isElectron ? (import.meta.env.VITE_ATM_PRIVATE_KEY as string | undefined) : ''
+    if (devKey) {
+      console.warn('[Signer] No bunker pairing — using LocalSigner from VITE_ATM_PRIVATE_KEY (dev)')
+      return new LocalSigner(loadIdentityFromHex(devKey))
+    }
+    console.warn('[Signer] No bunker pairing — generated ephemeral LocalSigner (dev only)')
+    return new LocalSigner(generateIdentity())
+  }
+
+  throw new Error(
+    '[Signer] No spire seed and no bunker binding — cannot resolve a signing identity (strict mode). ' +
+      'Set VITE_SPIRE_SEED or pair the ATM.'
+  )
+}