diff --git a/Sources/LocalData/Migrations/AppVersionConditionalMigration.swift b/Sources/LocalData/Migrations/AppVersionConditionalMigration.swift
index d434c1d..e6e02ff 100644
--- a/Sources/LocalData/Migrations/AppVersionConditionalMigration.swift
+++ b/Sources/LocalData/Migrations/AppVersionConditionalMigration.swift
@@ -1,15 +1,13 @@
 import Foundation
 
 /// Conditional migration for app version-based migration.
-public struct AppVersionConditionalMigration<Destination: StorageKey>: ConditionalMigration {
-    public typealias DestinationKey = Destination
-
-    public let destinationKey: Destination
+public struct AppVersionConditionalMigration<Value: Codable & Sendable>: ConditionalMigration {
+    public let destinationKey: StorageKey<Value>
     public let minAppVersion: String
     public let fallbackMigration: AnyStorageMigration
 
     public init(
-        destinationKey: Destination,
+        destinationKey: StorageKey<Value>,
         minAppVersion: String,
         fallbackMigration: AnyStorageMigration
     ) {
diff --git a/Sources/LocalData/Migrations/DefaultAggregatingMigration.swift b/Sources/LocalData/Migrations/DefaultAggregatingMigration.swift
index 90812f3..27b34dc 100644
--- a/Sources/LocalData/Migrations/DefaultAggregatingMigration.swift
+++ b/Sources/LocalData/Migrations/DefaultAggregatingMigration.swift
@@ -1,23 +1,21 @@
 import Foundation
 
-public struct DefaultAggregatingMigration<Destination: StorageKey>: AggregatingMigration {
-    public typealias DestinationKey = Destination
-
-    public let destinationKey: Destination
+public struct DefaultAggregatingMigration<Value: Codable & Sendable>: AggregatingMigration {
+    public let destinationKey: StorageKey<Value>
     public let sourceKeys: [AnyStorageKey]
-    public let aggregateAction: ([AnyCodable]) async throws -> Destination.Value
+    public let aggregateAction: ([AnyCodable]) async throws -> Value
 
     public init(
-        destinationKey: Destination,
+        destinationKey: StorageKey<Value>,
         sourceKeys: [AnyStorageKey],
-        aggregate: @escaping ([AnyCodable]) async throws -> Destination.Value
+        aggregate: @escaping ([AnyCodable]) async throws -> Value
     ) {
         self.destinationKey = destinationKey
         self.sourceKeys = sourceKeys
         self.aggregateAction = aggregate
     }
 
-    public func aggregate(_ sources: [AnyCodable]) async throws -> Destination.Value {
+    public func aggregate(_ sources: [AnyCodable]) async throws -> Value {
         try await aggregateAction(sources)
     }
 
diff --git a/Sources/LocalData/Migrations/DefaultTransformingMigration.swift b/Sources/LocalData/Migrations/DefaultTransformingMigration.swift
index b6c02d2..3ad8f44 100644
--- a/Sources/LocalData/Migrations/DefaultTransformingMigration.swift
+++ b/Sources/LocalData/Migrations/DefaultTransformingMigration.swift
@@ -1,24 +1,21 @@
 import Foundation
 
-public struct DefaultTransformingMigration<Source: StorageKey, Destination: StorageKey>: TransformingMigration {
-    public typealias SourceKey = Source
-    public typealias DestinationKey = Destination
-
-    public let destinationKey: Destination
-    public let sourceKey: Source
-    public let transformAction: (Source.Value) async throws -> Destination.Value
+public struct DefaultTransformingMigration<SourceValue: Codable & Sendable, DestinationValue: Codable & Sendable>: TransformingMigration {
+    public let destinationKey: StorageKey<DestinationValue>
+    public let sourceKey: StorageKey<SourceValue>
+    public let transformAction: (SourceValue) async throws -> DestinationValue
 
     public init(
-        destinationKey: Destination,
-        sourceKey: Source,
-        transform: @escaping (Source.Value) async throws -> Destination.Value
+        destinationKey: StorageKey<DestinationValue>,
+        sourceKey: StorageKey<SourceValue>,
+        transform: @escaping (SourceValue) async throws -> DestinationValue
     ) {
         self.destinationKey = destinationKey
         self.sourceKey = sourceKey
         self.transformAction = transform
     }
 
-    public func transform(_ source: Source.Value) async throws -> Destination.Value {
+    public func transform(_ source: SourceValue) async throws -> DestinationValue {
         try await transformAction(source)
     }
 
diff --git a/Sources/LocalData/Migrations/SimpleLegacyMigration.swift b/Sources/LocalData/Migrations/SimpleLegacyMigration.swift
index 332b8da..b48195a 100644
--- a/Sources/LocalData/Migrations/SimpleLegacyMigration.swift
+++ b/Sources/LocalData/Migrations/SimpleLegacyMigration.swift
@@ -1,13 +1,11 @@
 import Foundation
 
 /// Simple 1:1 legacy migration.
-public struct SimpleLegacyMigration<Destination: StorageKey>: StorageMigration {
-    public typealias DestinationKey = Destination
-
-    public let destinationKey: Destination
+public struct SimpleLegacyMigration<Value: Codable & Sendable>: StorageMigration {
+    public let destinationKey: StorageKey<Value>
     public let sourceKey: AnyStorageKey
 
-    public init(destinationKey: Destination, sourceKey: AnyStorageKey) {
+    public init(destinationKey: StorageKey<Value>, sourceKey: AnyStorageKey) {
         self.destinationKey = destinationKey
         self.sourceKey = sourceKey
     }
diff --git a/Sources/LocalData/Models/AnyStorageKey.swift b/Sources/LocalData/Models/AnyStorageKey.swift
index ee5904d..eed05ab 100644
--- a/Sources/LocalData/Models/AnyStorageKey.swift
+++ b/Sources/LocalData/Models/AnyStorageKey.swift
@@ -3,7 +3,7 @@ public struct AnyStorageKey: Sendable {
     public internal(set) var migration: AnyStorageMigration?
     private let migrateAction: @Sendable (StorageRouter) async throws -> Void
 
-    public init<Key: StorageKey>(_ key: Key) {
+    public init<Value>(_ key: StorageKey<Value>) {
         self.descriptor = .from(key)
         self.migration = key.migration
         self.migrateAction = { router in
@@ -21,7 +21,7 @@ public struct AnyStorageKey: Sendable {
         self.migrateAction = migrateAction
     }
 
-    public static func key<Key: StorageKey>(_ key: Key) -> AnyStorageKey {
+    public static func key<Value>(_ key: StorageKey<Value>) -> AnyStorageKey {
         AnyStorageKey(key)
     }
 
diff --git a/Sources/LocalData/Models/StorageKey.swift b/Sources/LocalData/Models/StorageKey.swift
new file mode 100644
index 0000000..718e5cc
--- /dev/null
+++ b/Sources/LocalData/Models/StorageKey.swift
@@ -0,0 +1,40 @@
+import Foundation
+
+public struct StorageKey<Value: Codable & Sendable>: Sendable, CustomStringConvertible {
+    public let name: String
+    public let domain: StorageDomain
+    public let security: SecurityPolicy
+    public let serializer: Serializer<Value>
+    public let owner: String
+    public let description: String
+    public let availability: PlatformAvailability
+    public let syncPolicy: SyncPolicy
+
+    private let migrationBuilder: (@Sendable (StorageKey<Value>) -> AnyStorageMigration?)?
+
+    public init(
+        name: String,
+        domain: StorageDomain,
+        security: SecurityPolicy = .recommended,
+        serializer: Serializer<Value> = .json,
+        owner: String,
+        description: String,
+        availability: PlatformAvailability = .all,
+        syncPolicy: SyncPolicy = .never,
+        migration: (@Sendable (StorageKey<Value>) -> AnyStorageMigration?)? = nil
+    ) {
+        self.name = name
+        self.domain = domain
+        self.security = security
+        self.serializer = serializer
+        self.owner = owner
+        self.description = description
+        self.availability = availability
+        self.syncPolicy = syncPolicy
+        self.migrationBuilder = migration
+    }
+
+    public var migration: AnyStorageMigration? {
+        migrationBuilder?(self)
+    }
+}
diff --git a/Sources/LocalData/Models/StorageKeyDescriptor.swift b/Sources/LocalData/Models/StorageKeyDescriptor.swift
index 719899b..d84cf15 100644
--- a/Sources/LocalData/Models/StorageKeyDescriptor.swift
+++ b/Sources/LocalData/Models/StorageKeyDescriptor.swift
@@ -36,8 +36,8 @@ public struct StorageKeyDescriptor: Sendable, CustomStringConvertible {
         self.catalog = catalog
     }
 
-    public static func from<Key: StorageKey>(
-        _ key: Key,
+    public static func from<Value>(
+        _ key: StorageKey<Value>,
         catalog: String? = nil
     ) -> StorageKeyDescriptor {
         StorageKeyDescriptor(
@@ -45,7 +45,7 @@ public struct StorageKeyDescriptor: Sendable, CustomStringConvertible {
             domain: key.domain,
             security: key.security,
             serializer: key.serializer.name,
-            valueType: String(describing: Key.Value.self),
+            valueType: String(describing: Value.self),
             owner: key.owner,
             availability: key.availability,
             syncPolicy: key.syncPolicy,
diff --git a/Sources/LocalData/Protocols/AggregatingMigration.swift b/Sources/LocalData/Protocols/AggregatingMigration.swift
index 704b8d4..83cb5c0 100644
--- a/Sources/LocalData/Protocols/AggregatingMigration.swift
+++ b/Sources/LocalData/Protocols/AggregatingMigration.swift
@@ -3,5 +3,5 @@ import Foundation
 /// Migration protocol that combines multiple sources into a single destination.
 public protocol AggregatingMigration: StorageMigration {
     var sourceKeys: [AnyStorageKey] { get }
-    func aggregate(_ sources: [AnyCodable]) async throws -> DestinationKey.Value
+    func aggregate(_ sources: [AnyCodable]) async throws -> Value
 }
diff --git a/Sources/LocalData/Protocols/StorageKey+Defaults.swift b/Sources/LocalData/Protocols/StorageKey+Defaults.swift
deleted file mode 100644
index e4073c2..0000000
--- a/Sources/LocalData/Protocols/StorageKey+Defaults.swift
+++ /dev/null
@@ -1,3 +0,0 @@
-public extension StorageKey {
-    var security: SecurityPolicy { .recommended }
-}
diff --git a/Sources/LocalData/Protocols/StorageKey.swift b/Sources/LocalData/Protocols/StorageKey.swift
deleted file mode 100644
index 9002be8..0000000
--- a/Sources/LocalData/Protocols/StorageKey.swift
+++ /dev/null
@@ -1,20 +0,0 @@
-import Foundation
-
-public protocol StorageKey: Sendable, CustomStringConvertible {
-    associatedtype Value: Codable & Sendable
-
-    var name: String { get }
-    var domain: StorageDomain { get }
-    var security: SecurityPolicy { get }
-    var serializer: Serializer<Value> { get }
-    var owner: String { get }
-
-    var availability: PlatformAvailability { get }
-    var syncPolicy: SyncPolicy { get }
-
-    var migration: AnyStorageMigration? { get }
-}
-
-extension StorageKey {
-    public var migration: AnyStorageMigration? { nil }
-}
diff --git a/Sources/LocalData/Protocols/StorageMigration.swift b/Sources/LocalData/Protocols/StorageMigration.swift
index 4995a52..64655c9 100644
--- a/Sources/LocalData/Protocols/StorageMigration.swift
+++ b/Sources/LocalData/Protocols/StorageMigration.swift
@@ -2,10 +2,10 @@ import Foundation
 
 /// Core migration protocol with high-level methods.
 public protocol StorageMigration: Sendable {
-    associatedtype DestinationKey: StorageKey
+    associatedtype Value: Codable & Sendable
 
     /// The destination storage key where migrated data will be stored.
-    var destinationKey: DestinationKey { get }
+    var destinationKey: StorageKey<Value> { get }
 
     /// Validate if migration should proceed (conditional logic).
     func shouldMigrate(using router: StorageRouter, context: MigrationContext) async throws -> Bool
diff --git a/Sources/LocalData/Protocols/StorageProviding.swift b/Sources/LocalData/Protocols/StorageProviding.swift
index 5cdffac..1034038 100644
--- a/Sources/LocalData/Protocols/StorageProviding.swift
+++ b/Sources/LocalData/Protocols/StorageProviding.swift
@@ -1,7 +1,7 @@
 import Foundation
 
 public protocol StorageProviding: Sendable {
-    func set<Key: StorageKey>(_ value: Key.Value, for key: Key) async throws
-    func get<Key: StorageKey>(_ key: Key) async throws -> Key.Value
-    func remove<Key: StorageKey>(_ key: Key) async throws
+    func set<Value>(_ value: Value, for key: StorageKey<Value>) async throws
+    func get<Value>(_ key: StorageKey<Value>) async throws -> Value
+    func remove<Value>(_ key: StorageKey<Value>) async throws
 }
diff --git a/Sources/LocalData/Protocols/TransformingMigration.swift b/Sources/LocalData/Protocols/TransformingMigration.swift
index df5db95..b063ba3 100644
--- a/Sources/LocalData/Protocols/TransformingMigration.swift
+++ b/Sources/LocalData/Protocols/TransformingMigration.swift
@@ -2,8 +2,8 @@ import Foundation
 
 /// Migration protocol that supports data transformation during migration.
 public protocol TransformingMigration: StorageMigration {
-    associatedtype SourceKey: StorageKey
+    associatedtype SourceValue: Codable & Sendable
 
-    var sourceKey: SourceKey { get }
-    func transform(_ source: SourceKey.Value) async throws -> DestinationKey.Value
+    var sourceKey: StorageKey<SourceValue> { get }
+    func transform(_ source: SourceValue) async throws -> Value
 }
diff --git a/Sources/LocalData/Services/StorageRouter.swift b/Sources/LocalData/Services/StorageRouter.swift
index d455746..741b5c2 100644
--- a/Sources/LocalData/Services/StorageRouter.swift
+++ b/Sources/LocalData/Services/StorageRouter.swift
@@ -127,7 +127,7 @@ public actor StorageRouter: StorageProviding {
     }
 
     /// Returns the last migration date for a specific key, if available.
-    public func migrationHistory<Key: StorageKey>(for key: Key) -> Date? {
+    public func migrationHistory<Value>(for key: StorageKey<Value>) -> Date? {
         migrationHistory[key.name]
     }
     
@@ -138,7 +138,7 @@ public actor StorageRouter: StorageProviding {
     ///   - value: The value to store.
     ///   - key: The storage key defining where and how to store.
     /// - Throws: Various errors depending on the storage domain and security policy.
-    public func set<Key: StorageKey>(_ value: Key.Value, for key: Key) async throws {
+    public func set<Value>(_ value: Value, for key: StorageKey<Value>) async throws {
         Logger.debug(">>> [STORAGE] SET: \(key.name) [Domain: \(key.domain)]")
         try validateCatalogRegistration(for: key)
         try validatePlatformAvailability(for: key)
@@ -155,7 +155,7 @@ public actor StorageRouter: StorageProviding {
     /// - Parameter key: The storage key to retrieve.
     /// - Returns: The stored value.
     /// - Throws: `StorageError.notFound` if no value exists, plus domain-specific errors.
-    public func get<Key: StorageKey>(_ key: Key) async throws -> Key.Value {
+    public func get<Value>(_ key: StorageKey<Value>) async throws -> Value {
         Logger.debug(">>> [STORAGE] GET: \(key.name)")
         try validateCatalogRegistration(for: key)
         try validatePlatformAvailability(for: key)
@@ -182,7 +182,7 @@ public actor StorageRouter: StorageProviding {
     /// - Parameter key: The storage key to migrate.
     /// - Returns: The migration result.
     /// - Throws: Migration or storage errors.
-    public func forceMigration<Key: StorageKey>(for key: Key) async throws -> MigrationResult {
+    public func forceMigration<Value>(for key: StorageKey<Value>) async throws -> MigrationResult {
         Logger.debug(">>> [STORAGE] MANUAL MIGRATION: \(key.name)")
         try validateCatalogRegistration(for: key)
 
@@ -207,7 +207,7 @@ public actor StorageRouter: StorageProviding {
     /// Removes the value for the given key.
     /// - Parameter key: The storage key to remove.
     /// - Throws: Domain-specific errors if removal fails.
-    public func remove<Key: StorageKey>(_ key: Key) async throws {
+    public func remove<Value>(_ key: StorageKey<Value>) async throws {
         try validateCatalogRegistration(for: key)
         try validatePlatformAvailability(for: key)
         try await delete(for: .from(key))
@@ -216,7 +216,7 @@ public actor StorageRouter: StorageProviding {
     /// Checks if a value exists for the given key.
     /// - Parameter key: The storage key to check.
     /// - Returns: True if a value exists.
-    public func exists<Key: StorageKey>(_ key: Key) async throws -> Bool {
+    public func exists<Value>(_ key: StorageKey<Value>) async throws -> Bool {
         try validateCatalogRegistration(for: key)
         try validatePlatformAvailability(for: key)
         
@@ -265,7 +265,7 @@ public actor StorageRouter: StorageProviding {
     
     // MARK: - Platform Validation
     
-    nonisolated private func validatePlatformAvailability<Key: StorageKey>(for key: Key) throws {
+    nonisolated private func validatePlatformAvailability<Value>(for key: StorageKey<Value>) throws {
         #if os(watchOS)
         if key.availability == .phoneOnly {
             throw StorageError.phoneOnlyKeyAccessedOnWatch(key.name)
@@ -277,7 +277,7 @@ public actor StorageRouter: StorageProviding {
         #endif
     }
 
-    private func validateCatalogRegistration<Key: StorageKey>(for key: Key) throws {
+    private func validateCatalogRegistration<Value>(for key: StorageKey<Value>) throws {
         guard !registeredKeys.isEmpty else { return }
         guard registeredKeys[key.name] != nil else {
             let errorMessage = "UNREGISTERED STORAGE KEY: '\(key.name)' (Owner: \(key.owner)) accessed but not found in any registered catalog. Did you forget to call registerCatalog?"
@@ -331,7 +331,7 @@ public actor StorageRouter: StorageProviding {
 
     // MARK: - Migration
 
-    private func attemptMigration<Key: StorageKey>(for key: Key) async throws -> Key.Value? {
+    private func attemptMigration<Value>(for key: StorageKey<Value>) async throws -> Value? {
         guard let migration = resolveMigration(for: key) else { return nil }
 
         let context = buildMigrationContext()
@@ -354,7 +354,7 @@ public actor StorageRouter: StorageProviding {
         return nil
     }
 
-    private func resolveMigration<Key: StorageKey>(for key: Key) -> AnyStorageMigration? {
+    private func resolveMigration<Value>(for key: StorageKey<Value>) -> AnyStorageMigration? {
         key.migration
     }
 
@@ -366,8 +366,8 @@ public actor StorageRouter: StorageProviding {
         migrationHistory[descriptor.name] = Date()
     }
 
-    internal func shouldAllowMigration<Key: StorageKey>(
-        for key: Key,
+    internal func shouldAllowMigration<Value>(
+        for key: StorageKey<Value>,
         context: MigrationContext
     ) async throws -> Bool {
         guard key.availability.isAvailable(on: context.deviceInfo.platform) else {
@@ -440,7 +440,7 @@ public actor StorageRouter: StorageProviding {
     
     // MARK: - Storage Operations
     
-    private func store(_ data: Data, for key: any StorageKey) async throws {
+    private func store<Value>(_ data: Data, for key: StorageKey<Value>) async throws {
         try await store(data, for: .from(key))
     }
     
@@ -544,7 +544,7 @@ public actor StorageRouter: StorageProviding {
     
     // MARK: - Sync
     
-    private func handleSync(_ key: any StorageKey, data: Data) async throws {
+    private func handleSync<Value>(_ key: StorageKey<Value>, data: Data) async throws {
         try await sync.syncIfNeeded(
             data: data,
             keyName: key.name,