fix(machine): resume from binding when a stored spire seed won't parse

resolveSigner parses the stored VITE_SPIRE_SEED on every boot before it checks
the binding, so a machine whose .env still holds a legacy-shape seed would
throw on the new parser (bitspire-#70) and surface "ATM Unavailable" on the
next auto-pull — even though it has a perfectly good, server-persistent binding
to resume from.

Guard the parse: an unparseable stored seed with a binding present falls back
to resuming the binding (authoritative); with no binding it still fails closed,
since the seed is then the only pairing input. Also dedupes the three
resume-from-binding call sites behind a small local.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

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

@@ -26,6 +26,7 @@ import {
   parseSpireSeed,
   seedFingerprint,
   type Signer,
+  type SpireSeed,
 } from '@bitSpire/nostr-client'
 import type { BunkerBindingRecord } from '@/types/electron'
 
@@ -67,17 +68,38 @@ async function loadPairingState(): Promise<PairingState> {
 export async function resolveSigner(opts: ResolveSignerOptions): Promise<Signer> {
   const { spireSeed, binding } = await loadPairingState()
 
+  const resume = (b: BunkerBindingRecord): Promise<Signer> =>
+    resumeFromBinding({
+      clientSecretHex: b.clientSecretHex,
+      spirePubkey: b.spirePubkey,
+      bunkerUrl: b.bunkerUrl,
+    })
+
   if (spireSeed) {
-    const seed = parseSpireSeed(spireSeed)
+    let seed: SpireSeed
-    const fingerprint = seedFingerprint(spireSeed)
+    let fingerprint: string
+    try {
+      seed = parseSpireSeed(spireSeed)
+      fingerprint = seedFingerprint(spireSeed)
+    } catch (err) {
+      // A stored seed we can't parse — e.g. a legacy-shape seed left in .env
+      // after the seed format changed (bitspire-#70). If we already hold a
+      // binding it's authoritative (server-persistent), so resume from it
+      // rather than bricking a paired machine on the next boot. With no
+      // binding the seed is our only pairing input, so fail closed.
+      if (binding) {
+        console.warn(
+          '[Signer] Stored spire seed is unparseable; resuming from existing binding:',
+          (err as Error).message,
+        )
+        return resume(binding)
+      }
+      throw err
+    }
 
     if (binding && binding.seedFingerprint === fingerprint) {
       console.log('[Signer] Resuming bunker session for spire', seed.spirePubkey)
-      return resumeFromBinding({
+      return resume(binding)
-        clientSecretHex: binding.clientSecretHex,
-        spirePubkey: binding.spirePubkey,
-        bunkerUrl: binding.bunkerUrl,
-      })
     }
 
     // First pair or re-pair: redeem the one-shot connect secret.
@@ -105,11 +127,7 @@ export async function resolveSigner(opts: ResolveSignerOptions): Promise<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({
+    return resume(binding)
-      clientSecretHex: binding.clientSecretHex,
-      spirePubkey: binding.spirePubkey,
-      bunkerUrl: binding.bunkerUrl,
-    })
   }
 
   if (opts.allowEphemeral) {