fix: refresh paykit key after wallet reset

Bitkit/Services/PubkyService.swift

@@ -1565,16 +1565,18 @@ final class PaykitReceiverNoiseKeyStore: @unchecked Sendable {
     }
 
     private func validatedKeyBytes() throws -> Data {
-        if let validatedBytes {
+        let storedBytes = try loadBytes()
+        if let validatedBytes, storedBytes == validatedBytes {
             return validatedBytes
         }
+        validatedBytes = nil
 
         let derivedBytes = try deriveBytes()
         guard derivedBytes.count == Self.keyLength else {
             throw invalidKeyError("Derived Paykit receiver Noise key is invalid")
         }
 
-        if let storedBytes = try loadBytes() {
+        if let storedBytes {
             guard storedBytes.count == Self.keyLength else {
                 throw invalidKeyError("Stored Paykit receiver Noise key is invalid")
             }

BitkitTests/PaykitReceiverNoiseKeyStoreTests.swift

@@ -54,6 +54,49 @@ final class PaykitReceiverNoiseKeyStoreTests: XCTestCase {
         XCTAssertEqual(persistedBytes, Data(repeating: 1, count: 32))
     }
 
+    func testReceiverNoiseKeyFollowsWalletReplacementAfterKeychainWipe() throws {
+        var persistedBytes: Data?
+        var derivedBytes = Data(repeating: 1, count: 32)
+        let store = PaykitReceiverNoiseKeyStore(
+            loadBytes: { persistedBytes },
+            upsertBytes: { persistedBytes = $0 },
+            deriveBytes: { derivedBytes }
+        )
+        let previousKey = try store.loadOrDerive()
+
+        persistedBytes = nil
+        derivedBytes = Data(repeating: 2, count: 32)
+
+        let replacementKey = try store.loadOrDerive().exportBytes()
+        XCTAssertEqual(replacementKey, derivedBytes)
+        XCTAssertEqual(persistedBytes, derivedBytes)
+        XCTAssertThrowsError(try store.persist(previousKey))
+
+        let restoredStore = PaykitReceiverNoiseKeyStore(
+            loadBytes: { persistedBytes },
+            upsertBytes: { persistedBytes = $0 },
+            deriveBytes: { derivedBytes }
+        )
+        XCTAssertEqual(try restoredStore.loadOrDerive().exportBytes(), replacementKey)
+    }
+
+    func testRejectsChangedPersistedKeyAfterCaching() throws {
+        let derivedBytes = Data(repeating: 1, count: 32)
+        var persistedBytes: Data? = derivedBytes
+        let store = PaykitReceiverNoiseKeyStore(
+            loadBytes: { persistedBytes },
+            upsertBytes: { _ in XCTFail("Invalid bytes must not be overwritten") },
+            deriveBytes: { derivedBytes }
+        )
+        _ = try store.loadOrDerive()
+
+        for invalidBytes in [Data(repeating: 1, count: 31), Data(repeating: 2, count: 32)] {
+            persistedBytes = invalidBytes
+            XCTAssertThrowsError(try store.loadOrDerive())
+            XCTAssertEqual(persistedBytes, invalidBytes)
+        }
+    }
+
     func testRejectsInvalidPersistedReceiverNoiseKey() {
         let store = PaykitReceiverNoiseKeyStore(
             loadBytes: { Data(repeating: 0, count: 31) },

changelog.d/next/761.fixed.md

@@ -0,0 +1 @@
+Fixed private payment connections reusing a previous wallet’s key after resetting the wallet.