wip: external signer

shared/src/commonMain/kotlin/su/reya/coop/ExternalSignerHandler.kt

@@ -0,0 +1,24 @@
+package su.reya.coop
+
+import rust.nostr.sdk.PublicKey
+import rust.nostr.sdk.UnsignedEvent
+
+/**
+ * Platform interface for NIP-55 external signer communication.
+ * Implemented on Android; no-op/null on other platforms.
+ */
+interface ExternalSignerHandler {
+    fun isAvailable(): Boolean
+
+    suspend fun getPublicKey(permissions: String? = null): ExternalSignerResult?
+    suspend fun signEvent(event: UnsignedEvent, currentUser: PublicKey): String?
+    suspend fun nip04Encrypt(plaintext: String, pubkey: PublicKey): String?
+    suspend fun nip04Decrypt(ciphertext: String, pubkey: PublicKey): String?
+    suspend fun nip44Encrypt(plaintext: String, pubkey: PublicKey, currentUser: PublicKey): String?
+    suspend fun nip44Decrypt(ciphertext: String, pubkey: PublicKey, currentUser: PublicKey): String?
+}
+
+data class ExternalSignerResult(
+    val pubkey: String,
+    val packageName: String,
+)

shared/src/commonMain/kotlin/su/reya/coop/ExternalSignerProxy.kt

@@ -0,0 +1,41 @@
+package su.reya.coop
+
+import rust.nostr.sdk.AsyncNostrSigner
+import rust.nostr.sdk.Event
+import rust.nostr.sdk.PublicKey
+import rust.nostr.sdk.UnsignedEvent
+
+class ExternalSignerProxy(
+    private val handler: ExternalSignerHandler,
+    private val packageName: String,
+    private val currentUser: PublicKey,
+) : AsyncNostrSigner {
+    override suspend fun getPublicKeyAsync(): PublicKey {
+        return currentUser
+    }
+
+    override suspend fun signEventAsync(unsignedEvent: UnsignedEvent): Event? {
+        val signedJson = handler.signEvent(unsignedEvent, currentUser) ?: return null
+        return Event.fromJson(signedJson)
+    }
+
+    override suspend fun nip04EncryptAsync(publicKey: PublicKey, content: String): String {
+        return handler.nip04Encrypt(content, publicKey)
+            ?: throw Exception("NIP-04 encrypt rejected")
+    }
+
+    override suspend fun nip04DecryptAsync(publicKey: PublicKey, encryptedContent: String): String {
+        return handler.nip04Decrypt(encryptedContent, publicKey)
+            ?: throw Exception("NIP-04 decrypt rejected")
+    }
+
+    override suspend fun nip44EncryptAsync(publicKey: PublicKey, content: String): String {
+        return handler.nip44Encrypt(content, publicKey, currentUser)
+            ?: throw Exception("NIP-44 encrypt rejected")
+    }
+
+    override suspend fun nip44DecryptAsync(publicKey: PublicKey, payload: String): String {
+        return handler.nip44Decrypt(payload, publicKey, currentUser)
+            ?: throw Exception("NIP-44 decrypt rejected")
+    }
+}

shared/src/commonMain/kotlin/su/reya/coop/NostrViewModel.kt

@@ -44,7 +44,8 @@ import kotlin.time.Duration.Companion.seconds
 
 class NostrViewModel(
     private val nostr: Nostr,
-    private val secretStore: SecretStorage
+    private val secretStore: SecretStorage,
+    private val externalSignerHandler: ExternalSignerHandler? = null,
 ) : ViewModel() {
     private val _isNotificationBannerDismissed = MutableStateFlow(false)
     val isNotificationBannerDismissed = _isNotificationBannerDismissed.asStateFlow()
@@ -374,6 +375,7 @@ class NostrViewModel(
     private suspend fun createSigner(secret: String): AsyncNostrSigner {
         return when {
             secret.startsWith("nsec1") -> Keys.parse(secret)
+
             secret.startsWith("bunker://") -> {
                 val appKeys = getOrInitAppKeys()
                 val bunker = NostrConnectUri.parse(secret)
@@ -381,6 +383,18 @@ class NostrViewModel(
                 NostrConnect(uri = bunker, appKeys, timeout, null)
             }
 
+            secret.startsWith("nip55://") -> {
+                val handler = externalSignerHandler
+                    ?: throw IllegalStateException("External signer not available on this platform")
+
+                // Format: nip55://packageName/hexPubkey
+                val parts = secret.removePrefix("nip55://").split("/", limit = 2)
+                val packageName = parts[0]
+                val pubkey = PublicKey.parse(parts[1])
+
+                ExternalSignerProxy(handler, packageName, pubkey)
+            }
+
             else -> throw IllegalArgumentException("Invalid secret format")
         }
     }