refactor: remove all dead legacy and migration code

- Remove unused migrateSession() functions (never called in production)
  - NoiseSession.migrateSession() - 13 lines
  - NoiseEncryptionService.migratePeerSession() - 18 lines
  - Test for migration functionality - 17 lines

- Remove unnecessary keychain cleanup code (no legacy data existed)
  - cleanupLegacyKeychainItems() - 62 lines
  - aggressiveCleanupLegacyItems() - 72 lines
  - resetCleanupFlag() - 4 lines
  - Simplified panic mode to just use deleteAllKeychainData()

Total removed: 194 lines of dead/unnecessary code

Analysis revealed:
- KeychainManager introduced July 5, 2025
- Cleanup code added July 15, 2025 (10 days later)
- Legacy service names were never used in production
- Migration functions were incomplete implementation never called
- Peer ID rotation remains active (not legacy)

5 files changed, 2 insertions, 196 deletions

diff --git a/bitchat/Noise/NoiseSession.swift b/bitchat/Noise/NoiseSession.swift
index bc327b5..005710a 100644
--- a/bitchat/Noise/NoiseSession.swift
+++ b/bitchat/Noise/NoiseSession.swift
@@ -296,19 +296,6 @@ class NoiseSessionManager {
         }
     }
     
-    func migrateSession(from oldPeerID: String, to newPeerID: String) {
-        managerQueue.sync(flags: .barrier) {
-            // Check if we have a session for the old peer ID
-            if let session = sessions[oldPeerID] {
-                // Move the session to the new peer ID
-                sessions[newPeerID] = session
-                _ = sessions.removeValue(forKey: oldPeerID)
-                
-                SecureLogger.log("Migrated Noise session from \(oldPeerID) to \(newPeerID)", category: SecureLogger.noise, level: .info)
-            }
-        }
-    }
-    
     func getEstablishedSessions() -> [String: NoiseSession] {
         return managerQueue.sync {
             return sessions.filter { $0.value.isEstablished() }
diff --git a/bitchat/Services/KeychainManager.swift b/bitchat/Services/KeychainManager.swift
index 5eee249..e863392 100644
--- a/bitchat/Services/KeychainManager.swift
+++ b/bitchat/Services/KeychainManager.swift
@@ -17,73 +17,7 @@ class KeychainManager {
     private let service = "chat.bitchat"
     private let appGroup = "group.chat.bitchat"
     
-    private init() {
-        // Clean up legacy keychain items on first run
-        cleanupLegacyKeychainItems()
-    }
-    
-    private func cleanupLegacyKeychainItems() {
-        // Check if we've already done cleanup
-        let cleanupKey = "bitchat.keychain.cleanup.v2"
-        if UserDefaults.standard.bool(forKey: cleanupKey) {
-            return
-        }
-        
-        
-        // List of old service names to migrate from
-        let legacyServices = [
-            "com.bitchat.passwords",
-            "com.bitchat.deviceidentity",
-            "com.bitchat.noise.identity",
-            "chat.bitchat.passwords",
-            "bitchat.keychain"
-        ]
-        
-        var migratedItems = 0
-        
-        // Try to migrate identity keys
-        for oldService in legacyServices {
-            // Check for noise identity key
-            let query: [String: Any] = [
-                kSecClass as String: kSecClassGenericPassword,
-                kSecAttrService as String: oldService,
-                kSecAttrAccount as String: "identity_noiseStaticKey",
-                kSecReturnData as String: true
-            ]
-            
-            var result: AnyObject?
-            let status = SecItemCopyMatching(query as CFDictionary, &result)
-            
-            if status == errSecSuccess, let data = result as? Data {
-                // Save to new service
-                if saveIdentityKey(data, forKey: "noiseStaticKey") {
-                    migratedItems += 1
-                    SecureLogger.logKeyOperation("migrate", keyType: "noiseStaticKey", success: true)
-                }
-                // Delete from old service
-                let deleteQuery: [String: Any] = [
-                    kSecClass as String: kSecClassGenericPassword,
-                    kSecAttrService as String: oldService,
-                    kSecAttrAccount as String: "identity_noiseStaticKey"
-                ]
-                SecItemDelete(deleteQuery as CFDictionary)
-            }
-        }
-        
-        // Clean up all other legacy items
-        for oldService in legacyServices {
-            let deleteQuery: [String: Any] = [
-                kSecClass as String: kSecClassGenericPassword,
-                kSecAttrService as String: oldService
-            ]
-            
-            SecItemDelete(deleteQuery as CFDictionary)
-        }
-        
-        
-        // Mark cleanup as done
-        UserDefaults.standard.set(true, forKey: cleanupKey)
-    }
+    private init() {}
     
     
     private func isSandboxed() -> Bool {
@@ -240,11 +174,6 @@ class KeychainManager {
         return status == errSecSuccess || status == errSecItemNotFound
     }
     
-    // Force cleanup to run again (for development/testing)
-    func resetCleanupFlag() {
-        UserDefaults.standard.removeObject(forKey: "bitchat.keychain.cleanup.v2")
-    }
-    
     
     // Delete ALL keychain data for panic mode
     func deleteAllKeychainData() -> Bool {
@@ -384,76 +313,4 @@ class KeychainManager {
         let key = "identity_noiseStaticKey"
         return retrieveData(forKey: key) != nil
     }
-    
-    // Aggressive cleanup for legacy items - can be called manually
-    func aggressiveCleanupLegacyItems() -> Int {
-        var deletedCount = 0
-        
-        // List of KNOWN bitchat service names from our development history
-        let knownBitchatServices = [
-            "com.bitchat.passwords",
-            "com.bitchat.deviceidentity",
-            "com.bitchat.noise.identity",
-            "chat.bitchat.passwords",
-            "bitchat.keychain",
-            "Bitchat",
-            "BitChat"
-        ]
-        
-        // First, delete all items from known legacy services
-        for legacyService in knownBitchatServices {
-            let deleteQuery: [String: Any] = [
-                kSecClass as String: kSecClassGenericPassword,
-                kSecAttrService as String: legacyService
-            ]
-            
-            let status = SecItemDelete(deleteQuery as CFDictionary)
-            if status == errSecSuccess {
-                deletedCount += 1
-            }
-        }
-        
-        // Now search for items that have our specific account patterns with bitchat service names
-        let searchQuery: [String: Any] = [
-            kSecClass as String: kSecClassGenericPassword,
-            kSecMatchLimit as String: kSecMatchLimitAll,
-            kSecReturnAttributes as String: true
-        ]
-        
-        var result: AnyObject?
-        let status = SecItemCopyMatching(searchQuery as CFDictionary, &result)
-        
-        if status == errSecSuccess, let items = result as? [[String: Any]] {
-            for item in items {
-                let account = item[kSecAttrAccount as String] as? String ?? ""
-                let service = item[kSecAttrService as String] as? String ?? ""
-                
-                // ONLY delete if service name contains "bitchat" somewhere
-                // This ensures we never touch other apps' keychain items
-                var shouldDelete = false
-                
-                // Check if service contains "bitchat" (case insensitive) but NOT our current service
-                let serviceLower = service.lowercased()
-                if service != self.service && serviceLower.contains("bitchat") {
-                    shouldDelete = true
-                }
-                
-                if shouldDelete {
-                    // Build precise delete query
-                    let deleteQuery: [String: Any] = [
-                        kSecClass as String: kSecClassGenericPassword,
-                        kSecAttrService as String: service,
-                        kSecAttrAccount as String: account
-                    ]
-                    
-                    let deleteStatus = SecItemDelete(deleteQuery as CFDictionary)
-                    if deleteStatus == errSecSuccess {
-                        deletedCount += 1
-                    }
-                }
-            }
-        }
-        
-        return deletedCount
-    }
 }
\ No newline at end of file
diff --git a/bitchat/Services/NoiseEncryptionService.swift b/bitchat/Services/NoiseEncryptionService.swift
index 09c9fe7..5cd6ae3 100644
--- a/bitchat/Services/NoiseEncryptionService.swift
+++ b/bitchat/Services/NoiseEncryptionService.swift
@@ -419,24 +419,6 @@ class NoiseEncryptionService {
         SecureLogger.logSecurityEvent(.sessionExpired(peerID: peerID))
     }
     
-    /// Migrate session when peer ID changes
-    func migratePeerSession(from oldPeerID: String, to newPeerID: String, fingerprint: String) {
-        // First update the fingerprint mappings
-        serviceQueue.sync(flags: .barrier) {
-            // Remove old mapping
-            if let oldFingerprint = peerFingerprints[oldPeerID], oldFingerprint == fingerprint {
-                peerFingerprints.removeValue(forKey: oldPeerID)
-            }
-            
-            // Add new mapping
-            peerFingerprints[newPeerID] = fingerprint
-            fingerprintToPeerID[fingerprint] = newPeerID
-        }
-        
-        // Migrate the session in session manager
-        sessionManager.migrateSession(from: oldPeerID, to: newPeerID)
-    }
-    
     // MARK: - Private Helpers
     
     private func handleSessionEstablished(peerID: String, remoteStaticKey: Curve25519.KeyAgreement.PublicKey) {
diff --git a/bitchat/ViewModels/ChatViewModel.swift b/bitchat/ViewModels/ChatViewModel.swift
index 6298db8..0827639 100644
--- a/bitchat/ViewModels/ChatViewModel.swift
+++ b/bitchat/ViewModels/ChatViewModel.swift
@@ -1474,10 +1474,7 @@ class ChatViewModel: ObservableObject, BitchatDelegate {
         privateChats.removeAll()
         unreadPrivateMessages.removeAll()
         
-        // First run aggressive cleanup to get rid of all legacy items
-        _ = KeychainManager.shared.aggressiveCleanupLegacyItems()
-        
-        // Then delete all current keychain data
+        // Delete all keychain data
         _ = KeychainManager.shared.deleteAllKeychainData()
         
         // Clear UserDefaults identity fallbacks
diff --git a/bitchatTests/Noise/NoiseProtocolTests.swift b/bitchatTests/Noise/NoiseProtocolTests.swift
index f54275d..be82ac7 100644
--- a/bitchatTests/Noise/NoiseProtocolTests.swift
+++ b/bitchatTests/Noise/NoiseProtocolTests.swift
@@ -226,23 +226,6 @@ final class NoiseProtocolTests: XCTestCase {
         XCTAssertEqual(decrypted, plaintext)
     }
     
-    func testSessionMigration() throws {
-        let manager = NoiseSessionManager(localStaticKey: aliceKey)
-        
-        // Create and establish a session
-        _ = try manager.initiateHandshake(with: TestConstants.testPeerID2)
-        
-        // Migrate to new peer ID
-        let newPeerID = TestConstants.testPeerID3
-        manager.migrateSession(from: TestConstants.testPeerID2, to: newPeerID)
-        
-        // Old peer ID should not have session
-        XCTAssertNil(manager.getSession(for: TestConstants.testPeerID2))
-        
-        // New peer ID should have the session
-        XCTAssertNotNil(manager.getSession(for: newPeerID))
-    }
-    
     // MARK: - Security Tests
     
     func testTamperedCiphertextDetection() throws {