diff --git a/Sources/LocalData/Audit/StorageAuditReport.swift b/Sources/LocalData/Audit/StorageAuditReport.swift
index 0326f58..dac8443 100644
--- a/Sources/LocalData/Audit/StorageAuditReport.swift
+++ b/Sources/LocalData/Audit/StorageAuditReport.swift
@@ -1,23 +1,29 @@
 import Foundation
 
+/// Renders audit reports for storage key catalogs and registries.
 public struct StorageAuditReport: Sendable {
+    /// Returns descriptors for all keys in a catalog.
     public static func items(for catalog: some StorageKeyCatalog) -> [StorageKeyDescriptor] {
         catalog.allKeys.map { $0.descriptor.withCatalog(catalog.name) }
     }
 
+    /// Renders a text report for a catalog.
     public static func renderText(_ catalog: some StorageKeyCatalog) -> String {
         renderText(items(for: catalog))
     }
 
+    /// Renders a text report for a list of type-erased keys.
     public static func renderText(_ entries: [AnyStorageKey]) -> String {
         renderText(entries.map(\.descriptor))
     }
 
+    /// Renders a text report for the global registry on the shared router.
     public static func renderGlobalRegistry() async -> String {
         let entries = await StorageRouter.shared.allRegisteredEntries()
         return renderText(entries)
     }
 
+    /// Renders a text report for the global registry grouped by catalog.
     public static func renderGlobalRegistryGrouped() async -> String {
         let catalogs = await StorageRouter.shared.allRegisteredCatalogs()
         var reportLines: [String] = []
@@ -34,6 +40,7 @@ public struct StorageAuditReport: Sendable {
         return reportLines.joined(separator: "\n")
     }
 
+    /// Renders a text report from storage key descriptors.
     public static func renderText(_ items: [StorageKeyDescriptor]) -> String {
         let lines = items.map { item in
             var parts: [String] = []
diff --git a/Sources/LocalData/Configuration/EncryptionConfiguration.swift b/Sources/LocalData/Configuration/EncryptionConfiguration.swift
index 851340a..e00f036 100644
--- a/Sources/LocalData/Configuration/EncryptionConfiguration.swift
+++ b/Sources/LocalData/Configuration/EncryptionConfiguration.swift
@@ -1,13 +1,19 @@
 import Foundation
 
-/// Configuration for the EncryptionHelper.
+/// Configuration for the encryption system.
 public struct EncryptionConfiguration: Sendable {
+    /// Keychain service for the master key.
     public let masterKeyService: String
+    /// Keychain account for the master key.
     public let masterKeyAccount: String
+    /// Master key length in bytes.
     public let masterKeyLength: Int
+    /// Default HKDF info string.
     public let defaultHKDFInfo: String
+    /// PBKDF2 iteration count.
     public let pbkdf2Iterations: Int
 
+    /// Creates an encryption configuration.
     public init(
         masterKeyService: String = "LocalData",
         masterKeyAccount: String = "MasterKey",
@@ -22,5 +28,6 @@ public struct EncryptionConfiguration: Sendable {
         self.pbkdf2Iterations = pbkdf2Iterations
     }
 
+    /// Default encryption configuration.
     public static let `default` = EncryptionConfiguration()
 }
diff --git a/Sources/LocalData/Configuration/FileStorageConfiguration.swift b/Sources/LocalData/Configuration/FileStorageConfiguration.swift
index 3568bb4..8351212 100644
--- a/Sources/LocalData/Configuration/FileStorageConfiguration.swift
+++ b/Sources/LocalData/Configuration/FileStorageConfiguration.swift
@@ -10,10 +10,12 @@ public struct FileStorageConfiguration: Sendable {
     /// Primarily used for testing isolation.
     public let baseURL: URL?
     
+    /// Creates a file storage configuration.
     public init(subDirectory: String? = nil, baseURL: URL? = nil) {
         self.subDirectory = subDirectory
         self.baseURL = baseURL
     }
     
+    /// Default file storage configuration.
     public static let `default` = FileStorageConfiguration()
 }
diff --git a/Sources/LocalData/Configuration/StorageConfiguration.swift b/Sources/LocalData/Configuration/StorageConfiguration.swift
index 8cb1d24..8c92cfa 100644
--- a/Sources/LocalData/Configuration/StorageConfiguration.swift
+++ b/Sources/LocalData/Configuration/StorageConfiguration.swift
@@ -9,6 +9,7 @@ public struct StorageConfiguration: Sendable {
     /// The default App Group identifier to use if none is specified in a StorageKey.
     public let defaultAppGroupIdentifier: String?
     
+    /// Creates a configuration with optional defaults.
     public init(
         defaultKeychainService: String? = nil,
         defaultAppGroupIdentifier: String? = nil
@@ -17,5 +18,6 @@ public struct StorageConfiguration: Sendable {
         self.defaultAppGroupIdentifier = defaultAppGroupIdentifier
     }
     
+    /// Default configuration with no predefined identifiers.
     public static let `default` = StorageConfiguration()
 }
diff --git a/Sources/LocalData/Configuration/SyncConfiguration.swift b/Sources/LocalData/Configuration/SyncConfiguration.swift
index 0350d72..7f3a1b1 100644
--- a/Sources/LocalData/Configuration/SyncConfiguration.swift
+++ b/Sources/LocalData/Configuration/SyncConfiguration.swift
@@ -5,9 +5,11 @@ public struct SyncConfiguration: Sendable {
     /// Maximum data size for automatic sync in bytes.
     public let maxAutoSyncSize: Int
     
+    /// Creates a sync configuration.
     public init(maxAutoSyncSize: Int = 100_000) {
         self.maxAutoSyncSize = maxAutoSyncSize
     }
     
+    /// Default sync configuration.
     public static let `default` = SyncConfiguration()
 }
diff --git a/Sources/LocalData/Migrations/AppVersionConditionalMigration.swift b/Sources/LocalData/Migrations/AppVersionConditionalMigration.swift
index e6e02ff..43e5f88 100644
--- a/Sources/LocalData/Migrations/AppVersionConditionalMigration.swift
+++ b/Sources/LocalData/Migrations/AppVersionConditionalMigration.swift
@@ -1,11 +1,15 @@
 import Foundation
 
-/// Conditional migration for app version-based migration.
+/// Conditional migration that runs only when the app version is below a threshold.
 public struct AppVersionConditionalMigration<Value: Codable & Sendable>: ConditionalMigration {
+    /// Destination key for the migration.
     public let destinationKey: StorageKey<Value>
+    /// Minimum app version required to skip this migration.
     public let minAppVersion: String
+    /// Migration to run when the version condition is met.
     public let fallbackMigration: AnyStorageMigration
 
+    /// Creates a version-gated migration.
     public init(
         destinationKey: StorageKey<Value>,
         minAppVersion: String,
diff --git a/Sources/LocalData/Migrations/DefaultAggregatingMigration.swift b/Sources/LocalData/Migrations/DefaultAggregatingMigration.swift
index b83371b..3abf3b7 100644
--- a/Sources/LocalData/Migrations/DefaultAggregatingMigration.swift
+++ b/Sources/LocalData/Migrations/DefaultAggregatingMigration.swift
@@ -1,10 +1,15 @@
 import Foundation
 
+/// Default migration that aggregates multiple source values into one destination value.
 public struct DefaultAggregatingMigration<Value: Codable & Sendable>: AggregatingMigration {
+    /// Destination key for aggregated data.
     public let destinationKey: StorageKey<Value>
+    /// Source keys providing legacy values.
     public let sourceKeys: [AnyStorageKey]
+    /// Async aggregation closure for source values.
     public let aggregateAction: @Sendable ([AnyCodable]) async throws -> Value
 
+    /// Creates an aggregating migration with a custom aggregation closure.
     public init(
         destinationKey: StorageKey<Value>,
         sourceKeys: [AnyStorageKey],
diff --git a/Sources/LocalData/Migrations/DefaultTransformingMigration.swift b/Sources/LocalData/Migrations/DefaultTransformingMigration.swift
index dcdcbea..d3feb41 100644
--- a/Sources/LocalData/Migrations/DefaultTransformingMigration.swift
+++ b/Sources/LocalData/Migrations/DefaultTransformingMigration.swift
@@ -1,10 +1,15 @@
 import Foundation
 
+/// Default migration that transforms a single source value into a destination value.
 public struct DefaultTransformingMigration<SourceValue: Codable & Sendable, DestinationValue: Codable & Sendable>: TransformingMigration {
+    /// Destination key for the transformed value.
     public let destinationKey: StorageKey<DestinationValue>
+    /// Source key providing the legacy value.
     public let sourceKey: StorageKey<SourceValue>
+    /// Async transform from source to destination.
     public let transformAction: @Sendable (SourceValue) async throws -> DestinationValue
 
+    /// Creates a transforming migration with a custom transform closure.
     public init(
         destinationKey: StorageKey<DestinationValue>,
         sourceKey: StorageKey<SourceValue>,
diff --git a/Sources/LocalData/Migrations/SimpleLegacyMigration.swift b/Sources/LocalData/Migrations/SimpleLegacyMigration.swift
index b48195a..e7f2cac 100644
--- a/Sources/LocalData/Migrations/SimpleLegacyMigration.swift
+++ b/Sources/LocalData/Migrations/SimpleLegacyMigration.swift
@@ -1,10 +1,13 @@
 import Foundation
 
-/// Simple 1:1 legacy migration.
+/// Simple 1:1 legacy migration from a single source key.
 public struct SimpleLegacyMigration<Value: Codable & Sendable>: StorageMigration {
+    /// Destination key for migrated data.
     public let destinationKey: StorageKey<Value>
+    /// Source key providing legacy data.
     public let sourceKey: AnyStorageKey
 
+    /// Creates a migration from a legacy key to a destination key.
     public init(destinationKey: StorageKey<Value>, sourceKey: AnyStorageKey) {
         self.destinationKey = destinationKey
         self.sourceKey = sourceKey
diff --git a/Sources/LocalData/Models/AnyCodable.swift b/Sources/LocalData/Models/AnyCodable.swift
index a1642e8..3024bc7 100644
--- a/Sources/LocalData/Models/AnyCodable.swift
+++ b/Sources/LocalData/Models/AnyCodable.swift
@@ -1,8 +1,14 @@
 import Foundation
 
+/// Type-erased `Codable` wrapper for mixed-type payloads.
+///
+/// - Important: `AnyCodable` is `@unchecked Sendable` because `Any` cannot be verified by the
+///   compiler. Callers should only store values that are safe to pass across concurrency domains.
 public struct AnyCodable: Codable, @unchecked Sendable {
+    /// Underlying value (Bool, Int, Double, String, arrays, or dictionaries).
     public let value: Any
 
+    /// Wraps a value for encoding or decoding.
     public init(_ value: Any) {
         self.value = value
     }
diff --git a/Sources/LocalData/Models/AnyStorageKey.swift b/Sources/LocalData/Models/AnyStorageKey.swift
index eed05ab..4ec2327 100644
--- a/Sources/LocalData/Models/AnyStorageKey.swift
+++ b/Sources/LocalData/Models/AnyStorageKey.swift
@@ -1,8 +1,12 @@
+/// Type-erased wrapper around ``StorageKey`` for catalogs and audits.
 public struct AnyStorageKey: Sendable {
+    /// Snapshot of key metadata for auditing and storage operations.
     public internal(set) var descriptor: StorageKeyDescriptor
+    /// Optional migration associated with the key.
     public internal(set) var migration: AnyStorageMigration?
     private let migrateAction: @Sendable (StorageRouter) async throws -> Void
 
+    /// Creates a type-erased key from a typed ``StorageKey``.
     public init<Value>(_ key: StorageKey<Value>) {
         self.descriptor = .from(key)
         self.migration = key.migration
@@ -21,6 +25,7 @@ public struct AnyStorageKey: Sendable {
         self.migrateAction = migrateAction
     }
 
+    /// Convenience factory for creating a type-erased key.
     public static func key<Value>(_ key: StorageKey<Value>) -> AnyStorageKey {
         AnyStorageKey(key)
     }
diff --git a/Sources/LocalData/Models/AnyStorageMigration.swift b/Sources/LocalData/Models/AnyStorageMigration.swift
index 839d9a6..fd727ad 100644
--- a/Sources/LocalData/Models/AnyStorageMigration.swift
+++ b/Sources/LocalData/Models/AnyStorageMigration.swift
@@ -1,12 +1,14 @@
 import Foundation
 
-/// Type-erased wrapper for StorageMigration to match AnyStorageKey patterns.
+/// Type-erased wrapper for ``StorageMigration`` for use in catalogs and registrations.
 public struct AnyStorageMigration: Sendable {
+    /// Descriptor for the migration destination key.
     public let destinationDescriptor: StorageKeyDescriptor
 
     private let shouldMigrateAction: @Sendable (StorageRouter, MigrationContext) async throws -> Bool
     private let migrateAction: @Sendable (StorageRouter, MigrationContext) async throws -> MigrationResult
 
+    /// Creates a type-erased migration from a concrete migration.
     public init<M: StorageMigration>(_ migration: M) {
         self.destinationDescriptor = .from(migration.destinationKey)
         self.shouldMigrateAction = { @Sendable router, context in
@@ -17,10 +19,12 @@ public struct AnyStorageMigration: Sendable {
         }
     }
 
+    /// Evaluates whether the migration should run for the given context.
     public func shouldMigrate(using router: StorageRouter, context: MigrationContext) async throws -> Bool {
         try await shouldMigrateAction(router, context)
     }
 
+    /// Executes the migration and returns its result.
     public func migrate(using router: StorageRouter, context: MigrationContext) async throws -> MigrationResult {
         try await migrateAction(router, context)
     }
diff --git a/Sources/LocalData/Models/FileDirectory.swift b/Sources/LocalData/Models/FileDirectory.swift
index ed04e15..01a089a 100644
--- a/Sources/LocalData/Models/FileDirectory.swift
+++ b/Sources/LocalData/Models/FileDirectory.swift
@@ -1,7 +1,15 @@
 import Foundation
 
+/// File system directory for file-based storage.
 public enum FileDirectory: Sendable, Hashable {
-    case documents, caches, custom(URL)
+    /// App documents directory.
+    case documents
+    /// App caches directory.
+    case caches
+    /// Custom directory URL.
+    case custom(URL)
+
+    /// Resolves the directory to a concrete URL.
     public func url() -> URL {
         switch self {
         case .documents:
diff --git a/Sources/LocalData/Models/KeyMaterialSource.swift b/Sources/LocalData/Models/KeyMaterialSource.swift
index 3ba6a2b..bf822cd 100644
--- a/Sources/LocalData/Models/KeyMaterialSource.swift
+++ b/Sources/LocalData/Models/KeyMaterialSource.swift
@@ -1,8 +1,11 @@
 import Foundation
 
+/// Identifier for external key material providers.
 public struct KeyMaterialSource: Hashable, Sendable {
+    /// Stable identifier for the provider or key source.
     public let id: String
 
+    /// Creates a new key material source identifier.
     public init(id: String) {
         self.id = id
     }
diff --git a/Sources/LocalData/Models/MigrationContext.swift b/Sources/LocalData/Models/MigrationContext.swift
index 78e775b..8e87ede 100644
--- a/Sources/LocalData/Models/MigrationContext.swift
+++ b/Sources/LocalData/Models/MigrationContext.swift
@@ -2,12 +2,18 @@ import Foundation
 
 /// Context information available for conditional migrations.
 public struct MigrationContext: Sendable {
+    /// Current app version string.
     public let appVersion: String
+    /// Device metadata for platform checks.
     public let deviceInfo: DeviceInfo
+    /// Previously recorded migration timestamps keyed by storage key name.
     public let migrationHistory: [String: Date]
+    /// Caller-provided preferences that may influence migration behavior.
     public let userPreferences: [String: AnyCodable]
+    /// System information for conditional checks.
     public let systemInfo: SystemInfo
 
+    /// Creates a migration context with optional overrides.
     public init(
         appVersion: String = Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String ?? "Unknown",
         deviceInfo: DeviceInfo = .current,
diff --git a/Sources/LocalData/Models/MigrationError.swift b/Sources/LocalData/Models/MigrationError.swift
index d44b46e..6638d38 100644
--- a/Sources/LocalData/Models/MigrationError.swift
+++ b/Sources/LocalData/Models/MigrationError.swift
@@ -2,13 +2,21 @@ import Foundation
 
 /// Migration-specific error types.
 public enum MigrationError: Error, Sendable, Equatable {
+    /// Validation failed before migration could run.
     case validationFailed(String)
+    /// Transformation failed while converting source to destination.
     case transformationFailed(String)
+    /// Underlying storage error occurred.
     case storageFailed(StorageError)
+    /// Conditional migration criteria were not met.
     case conditionalMigrationFailed
+    /// A migration is already in progress for the key.
     case migrationInProgress
+    /// No source data was found to migrate.
     case sourceDataNotFound
+    /// Source and destination types are incompatible.
     case incompatibleTypes(String)
+    /// Aggregation failed while combining multiple sources.
     case aggregationFailed(String)
 }
 
diff --git a/Sources/LocalData/Models/MigrationResult.swift b/Sources/LocalData/Models/MigrationResult.swift
index c98c39f..3308aef 100644
--- a/Sources/LocalData/Models/MigrationResult.swift
+++ b/Sources/LocalData/Models/MigrationResult.swift
@@ -2,12 +2,18 @@ import Foundation
 
 /// Result of a migration operation with detailed information.
 public struct MigrationResult: Sendable {
+    /// Whether the migration completed successfully.
     public let success: Bool
+    /// Number of values migrated.
     public let migratedCount: Int
+    /// Errors captured during migration.
     public let errors: [MigrationError]
+    /// Additional metadata provided by the migration.
     public let metadata: [String: AnyCodable]
+    /// Duration of the migration in seconds.
     public let duration: TimeInterval
 
+    /// Creates a migration result with optional details.
     public init(
         success: Bool,
         migratedCount: Int = 0,
diff --git a/Sources/LocalData/Models/PlatformAvailability.swift b/Sources/LocalData/Models/PlatformAvailability.swift
index ac198fa..72354e2 100644
--- a/Sources/LocalData/Models/PlatformAvailability.swift
+++ b/Sources/LocalData/Models/PlatformAvailability.swift
@@ -1,13 +1,19 @@
 import Foundation
 
+/// Specifies which platforms a storage key is allowed to run on.
 public enum PlatformAvailability: Sendable {
-    case all                    // iPhone + Watch (small only!)
-    case phoneOnly              // iPhone only (large/sensitive)
-    case watchOnly              // Watch local only
-    case phoneWithWatchSync     // Small data for explicit sync
+    /// Available on iOS and watchOS (small data only on watch).
+    case all
+    /// Available only on iOS (large or sensitive data).
+    case phoneOnly
+    /// Available only on watchOS.
+    case watchOnly
+    /// Available on iOS and watchOS with explicit sync behavior.
+    case phoneWithWatchSync
 }
 
 public extension PlatformAvailability {
+    /// Returns `true` if the key should be available on the given platform.
     func isAvailable(on platform: Platform) -> Bool {
         switch self {
         case .all:
diff --git a/Sources/LocalData/Models/SecurityPolicy.swift b/Sources/LocalData/Models/SecurityPolicy.swift
index dc75a06..f2db56b 100644
--- a/Sources/LocalData/Models/SecurityPolicy.swift
+++ b/Sources/LocalData/Models/SecurityPolicy.swift
@@ -2,26 +2,40 @@ import Foundation
 import CryptoKit
 import Security
 
+/// Security policy for a ``StorageKey``.
 public enum SecurityPolicy: Equatable, Sendable {
+    /// Stores data without additional security.
     case none
+    /// Encrypts data before storage using the specified policy.
     case encrypted(EncryptionPolicy)
+    /// Stores data directly in the Keychain with accessibility and access control options.
     case keychain(accessibility: KeychainAccessibility, accessControl: KeychainAccessControl?)
 
+    /// Recommended security policy for most sensitive data.
     public static let recommended: SecurityPolicy = .encrypted(.recommended)
 
+    /// Encryption algorithm and key derivation settings.
     public enum EncryptionPolicy: Equatable, Sendable {
+        /// AES-256-GCM encryption.
         case aes256(keyDerivation: KeyDerivation)
+        /// ChaCha20-Poly1305 encryption.
         case chacha20Poly1305(keyDerivation: KeyDerivation)
+        /// External key material with key derivation.
         case external(source: KeyMaterialSource, keyDerivation: KeyDerivation)
 
+        /// Recommended encryption policy for most cases.
         public static let recommended: EncryptionPolicy = .chacha20Poly1305(keyDerivation: .hkdf())
+        /// Convenience for external key material with default HKDF.
         public static func external(source: KeyMaterialSource) -> EncryptionPolicy {
             .external(source: source, keyDerivation: .hkdf())
         }
     }
 
+    /// Key derivation algorithms for encryption keys.
     public enum KeyDerivation: Equatable, Sendable {
+        /// PBKDF2 with optional iterations and salt.
         case pbkdf2(iterations: Int? = nil, salt: Data? = nil)
+        /// HKDF with optional salt and info.
         case hkdf(salt: Data? = nil, info: Data? = nil)
     }
 }
diff --git a/Sources/LocalData/Models/Serializer.swift b/Sources/LocalData/Models/Serializer.swift
index 8ae3ee9..9a317ad 100644
--- a/Sources/LocalData/Models/Serializer.swift
+++ b/Sources/LocalData/Models/Serializer.swift
@@ -1,10 +1,20 @@
 import Foundation
 
+/// Encodes and decodes values for storage.
 public struct Serializer<Value: Codable & Sendable>: Sendable, CustomStringConvertible {
+    /// Encodes a value into `Data`.
     public let encode: @Sendable (Value) throws -> Data
+    /// Decodes a value from `Data`.
     public let decode: @Sendable (Data) throws -> Value
+    /// Human-readable serializer name used in audit reports.
     public let name: String
 
+    /// Creates a custom serializer.
+    ///
+    /// - Parameters:
+    ///   - encode: Encoder for values.
+    ///   - decode: Decoder for values.
+    ///   - name: Display name for audit and logging.
     public init(
         encode: @escaping @Sendable (Value) throws -> Data,
         decode: @escaping @Sendable (Data) throws -> Value,
@@ -15,8 +25,10 @@ public struct Serializer<Value: Codable & Sendable>: Sendable, CustomStringConve
         self.name = name
     }
 
+    /// Description used by `CustomStringConvertible`.
     public var description: String { name }
 
+    /// JSON serializer using `JSONEncoder` and `JSONDecoder`.
     public static var json: Serializer<Value> {
         Serializer<Value>(
             encode: { try JSONEncoder().encode($0) },
@@ -25,6 +37,7 @@ public struct Serializer<Value: Codable & Sendable>: Sendable, CustomStringConve
         )
     }
 
+    /// Property list serializer using `PropertyListEncoder` and `PropertyListDecoder`.
     public static var plist: Serializer<Value> {
         Serializer<Value>(
             encode: { try PropertyListEncoder().encode($0) },
@@ -33,6 +46,7 @@ public struct Serializer<Value: Codable & Sendable>: Sendable, CustomStringConve
         )
     }
 
+    /// Convenience for custom serializers.
     public static func custom(
         encode: @escaping @Sendable (Value) throws -> Data,
         decode: @escaping @Sendable (Data) throws -> Value,
@@ -43,6 +57,7 @@ public struct Serializer<Value: Codable & Sendable>: Sendable, CustomStringConve
 }
 
 public extension Serializer where Value == Data {
+    /// Serializer that passes through raw `Data`.
     static var data: Serializer<Value> {
         Serializer<Value>(encode: { $0 }, decode: { $0 }, name: "data")
     }
diff --git a/Sources/LocalData/Models/StorageDomain.swift b/Sources/LocalData/Models/StorageDomain.swift
index 010439f..8eb011b 100644
--- a/Sources/LocalData/Models/StorageDomain.swift
+++ b/Sources/LocalData/Models/StorageDomain.swift
@@ -1,10 +1,17 @@
 import Foundation
 
+/// Storage location for a ``StorageKey``.
 public enum StorageDomain: Sendable, Equatable {
+    /// Standard `UserDefaults` using the provided suite name.
     case userDefaults(suite: String?)
+    /// App group `UserDefaults` using the provided group identifier.
     case appGroupUserDefaults(identifier: String?)
+    /// Keychain storage using the provided service identifier.
     case keychain(service: String?)
+    /// File system storage in the specified directory.
     case fileSystem(directory: FileDirectory)
+    /// Encrypted file system storage in the specified directory.
     case encryptedFileSystem(directory: FileDirectory)
+    /// App group file storage using the group identifier and directory.
     case appGroupFileSystem(identifier: String?, directory: FileDirectory)
 }
diff --git a/Sources/LocalData/Models/StorageError.swift b/Sources/LocalData/Models/StorageError.swift
index 953fecd..d05bee0 100644
--- a/Sources/LocalData/Models/StorageError.swift
+++ b/Sources/LocalData/Models/StorageError.swift
@@ -1,18 +1,34 @@
 import Foundation
 
+/// Errors thrown by storage operations and migrations.
 public enum StorageError: Error, Equatable {
-    case serializationFailed, deserializationFailed
+    /// Failed to encode a value.
+    case serializationFailed
+    /// Failed to decode stored data.
+    case deserializationFailed
+    /// Failed to apply or remove security for stored data.
     case securityApplicationFailed
+    /// Underlying Keychain error.
     case keychainError(OSStatus)
+    /// File system error description.
     case fileError(String) // Changed from Error to String for easier Equatable conformance
+    /// A phone-only key was accessed on watchOS.
     case phoneOnlyKeyAccessedOnWatch(String)
+    /// A watch-only key was accessed on iOS.
     case watchOnlyKeyAccessedOnPhone(String)
+    /// Invalid UserDefaults suite name.
     case invalidUserDefaultsSuite(String)
+    /// Invalid App Group identifier.
     case invalidAppGroupIdentifier(String)
+    /// Sync payload exceeded the configured maximum size.
     case dataTooLargeForSync
+    /// No value exists for the requested key.
     case notFound
+    /// The key is not registered in any catalog.
     case unregisteredKey(String)
+    /// Duplicate key names detected during registration.
     case duplicateRegisteredKeys([String])
+    /// Missing or empty key description.
     case missingDescription(String)
 
     public static func == (lhs: StorageError, rhs: StorageError) -> Bool {
diff --git a/Sources/LocalData/Models/StorageKey.swift b/Sources/LocalData/Models/StorageKey.swift
index 718e5cc..b6cb0e3 100644
--- a/Sources/LocalData/Models/StorageKey.swift
+++ b/Sources/LocalData/Models/StorageKey.swift
@@ -1,17 +1,47 @@
 import Foundation
 
+/// Typed descriptor for a single piece of persisted data.
+///
+/// Use `StorageKey` to define where a value is stored, how it is secured, how it is serialized,
+/// and how it participates in sync and migration behaviors.
+///
+/// - Important: `name` should be unique within its storage domain to avoid collisions.
+/// - Note: `Value` must conform to `Codable` and `Sendable`.
 public struct StorageKey<Value: Codable & Sendable>: Sendable, CustomStringConvertible {
+    /// Unique identifier for the stored value within its domain.
     public let name: String
+    /// Storage location for the value (UserDefaults, Keychain, file system, etc.).
     public let domain: StorageDomain
+    /// Security policy applied to stored bytes.
     public let security: SecurityPolicy
+    /// Serializer used to convert between `Value` and `Data`.
     public let serializer: Serializer<Value>
+    /// Owning feature or module for auditability.
     public let owner: String
+    /// Human-readable description for audit reports.
     public let description: String
+    /// Platform availability constraints for reads/writes and migrations.
     public let availability: PlatformAvailability
+    /// WatchConnectivity sync behavior for this key.
     public let syncPolicy: SyncPolicy
 
+    /// Lazily builds a migration using the fully initialized key.
+    ///
+    /// This avoids capturing `self` during initialization and keeps the destination key consistent.
     private let migrationBuilder: (@Sendable (StorageKey<Value>) -> AnyStorageMigration?)?
 
+    /// Creates a storage key with optional security, serializer, availability, sync, and migration.
+    ///
+    /// - Parameters:
+    ///   - name: Unique identifier for the stored value.
+    ///   - domain: Storage location for the value.
+    ///   - security: Security policy applied to stored bytes. Defaults to `.recommended`.
+    ///   - serializer: Serializer used to encode/decode values. Defaults to `.json`.
+    ///   - owner: Owning feature or module for auditability.
+    ///   - description: Human-readable description for audit reports.
+    ///   - availability: Platform availability constraints. Defaults to `.all`.
+    ///   - syncPolicy: WatchConnectivity sync behavior. Defaults to `.never`.
+    ///   - migration: Optional builder that creates a migration using this key as destination.
     public init(
         name: String,
         domain: StorageDomain,
@@ -34,6 +64,9 @@ public struct StorageKey<Value: Codable & Sendable>: Sendable, CustomStringConve
         self.migrationBuilder = migration
     }
 
+    /// Construct a migration on demand using this key as the destination.
+    ///
+    /// - Returns: The migration for this key, or `nil` if none is configured.
     public var migration: AnyStorageMigration? {
         migrationBuilder?(self)
     }
diff --git a/Sources/LocalData/Models/StorageKeyDescriptor.swift b/Sources/LocalData/Models/StorageKeyDescriptor.swift
index d84cf15..be4c8c7 100644
--- a/Sources/LocalData/Models/StorageKeyDescriptor.swift
+++ b/Sources/LocalData/Models/StorageKeyDescriptor.swift
@@ -1,15 +1,26 @@
 import Foundation
 
+/// Snapshot of a ``StorageKey`` used for audit and registration.
 public struct StorageKeyDescriptor: Sendable, CustomStringConvertible {
+    /// Key name within its domain.
     public let name: String
+    /// Storage domain for the key.
     public let domain: StorageDomain
+    /// Security policy applied to the key.
     public let security: SecurityPolicy
+    /// Serializer name used for encoding/decoding.
     public let serializer: String
+    /// String representation of the value type.
     public let valueType: String
+    /// Owning module or feature name.
     public let owner: String
+    /// Platform availability for the key.
     public let availability: PlatformAvailability
+    /// Sync policy for WatchConnectivity.
     public let syncPolicy: SyncPolicy
+    /// Human-readable description for audit reports.
     public let description: String
+    /// Optional catalog name the key belongs to.
     public let catalog: String?
 
     init(
@@ -36,6 +47,7 @@ public struct StorageKeyDescriptor: Sendable, CustomStringConvertible {
         self.catalog = catalog
     }
 
+    /// Builds a descriptor from a ``StorageKey``.
     public static func from<Value>(
         _ key: StorageKey<Value>,
         catalog: String? = nil
diff --git a/Sources/LocalData/Models/SyncPolicy.swift b/Sources/LocalData/Models/SyncPolicy.swift
index 355ebfc..2430c69 100644
--- a/Sources/LocalData/Models/SyncPolicy.swift
+++ b/Sources/LocalData/Models/SyncPolicy.swift
@@ -1,7 +1,11 @@
 import Foundation
 
+/// Defines how a key participates in WatchConnectivity sync.
 public enum SyncPolicy: Sendable {
-    case never                  // Default for most
-    case manual                 // Manual WCSession send
-    case automaticSmall         // Auto-sync if small
+    /// No sync behavior.
+    case never
+    /// Sync only when the app explicitly requests it.
+    case manual
+    /// Automatically sync when data size is below the configured threshold.
+    case automaticSmall
 }
diff --git a/Sources/LocalData/Protocols/AggregatingMigration.swift b/Sources/LocalData/Protocols/AggregatingMigration.swift
index 83cb5c0..4d6eec1 100644
--- a/Sources/LocalData/Protocols/AggregatingMigration.swift
+++ b/Sources/LocalData/Protocols/AggregatingMigration.swift
@@ -2,6 +2,8 @@ import Foundation
 
 /// Migration protocol that combines multiple sources into a single destination.
 public protocol AggregatingMigration: StorageMigration {
+    /// The set of source keys used to build the destination value.
     var sourceKeys: [AnyStorageKey] { get }
+    /// Aggregates decoded source values into the destination value type.
     func aggregate(_ sources: [AnyCodable]) async throws -> Value
 }
diff --git a/Sources/LocalData/Protocols/KeyMaterialProviding.swift b/Sources/LocalData/Protocols/KeyMaterialProviding.swift
index ba364b7..c328f50 100644
--- a/Sources/LocalData/Protocols/KeyMaterialProviding.swift
+++ b/Sources/LocalData/Protocols/KeyMaterialProviding.swift
@@ -1,5 +1,7 @@
 import Foundation
 
+/// Supplies external key material for encryption policies.
 public protocol KeyMaterialProviding: Sendable {
+    /// Returns key material associated with the given key name.
     func keyMaterial(for keyName: String) async throws -> Data
 }
diff --git a/Sources/LocalData/Protocols/KeychainStoring.swift b/Sources/LocalData/Protocols/KeychainStoring.swift
index e22ad3f..2c10f37 100644
--- a/Sources/LocalData/Protocols/KeychainStoring.swift
+++ b/Sources/LocalData/Protocols/KeychainStoring.swift
@@ -1,8 +1,10 @@
 import Foundation
 
 /// Protocol defining the interface for Keychain operations.
-/// Allows for dependency injection and mocking in tests.
+///
+/// Conformers enable dependency injection and mocking in tests.
 public protocol KeychainStoring: Sendable {
+    /// Stores data for a keychain entry.
     func set(
         _ data: Data,
         service: String,
@@ -11,11 +13,15 @@ public protocol KeychainStoring: Sendable {
         accessControl: KeychainAccessControl?
     ) async throws
     
+    /// Retrieves data for a keychain entry.
     func get(service: String, key: String) async throws -> Data?
     
+    /// Deletes a keychain entry.
     func delete(service: String, key: String) async throws
     
+    /// Checks if a keychain entry exists.
     func exists(service: String, key: String) async throws -> Bool
     
+    /// Deletes all keychain entries for a service.
     func deleteAll(service: String) async throws
 }
diff --git a/Sources/LocalData/Protocols/StorageKeyCatalog.swift b/Sources/LocalData/Protocols/StorageKeyCatalog.swift
index 38e25a5..60c365d 100644
--- a/Sources/LocalData/Protocols/StorageKeyCatalog.swift
+++ b/Sources/LocalData/Protocols/StorageKeyCatalog.swift
@@ -1,9 +1,13 @@
+/// Collection of storage keys used for registration and auditing.
 public protocol StorageKeyCatalog: Sendable {
+    /// Human-readable catalog name used in audit reports.
     var name: String { get }
+    /// All keys owned by this catalog.
     var allKeys: [AnyStorageKey] { get }
 }
 
 extension StorageKeyCatalog {
+    /// Default catalog name derived from the type name.
     public var name: String {
         let fullName = String(describing: type(of: self))
         // Simple cleanup for generic or nested names if needed, 
diff --git a/Sources/LocalData/Protocols/StorageMigration.swift b/Sources/LocalData/Protocols/StorageMigration.swift
index 64655c9..ff222ec 100644
--- a/Sources/LocalData/Protocols/StorageMigration.swift
+++ b/Sources/LocalData/Protocols/StorageMigration.swift
@@ -1,20 +1,22 @@
 import Foundation
 
-/// Core migration protocol with high-level methods.
+/// Core migration protocol for moving data into a destination ``StorageKey``.
 public protocol StorageMigration: Sendable {
+    /// The value type produced by the migration.
     associatedtype Value: Codable & Sendable
 
     /// The destination storage key where migrated data will be stored.
     var destinationKey: StorageKey<Value> { get }
 
-    /// Validate if migration should proceed (conditional logic).
+    /// Determines whether the migration should run for the given context.
     func shouldMigrate(using router: StorageRouter, context: MigrationContext) async throws -> Bool
 
-    /// Execute the migration process.
+    /// Executes the migration and returns a result describing success or failure.
     func migrate(using router: StorageRouter, context: MigrationContext) async throws -> MigrationResult
 }
 
 public extension StorageMigration {
+    /// Default conditional behavior that checks platform availability and existing data.
     func shouldMigrate(using router: StorageRouter, context: MigrationContext) async throws -> Bool {
         try await router.shouldAllowMigration(for: destinationKey, context: context)
     }
diff --git a/Sources/LocalData/Protocols/StorageProviding.swift b/Sources/LocalData/Protocols/StorageProviding.swift
index 1034038..4ab45ab 100644
--- a/Sources/LocalData/Protocols/StorageProviding.swift
+++ b/Sources/LocalData/Protocols/StorageProviding.swift
@@ -1,7 +1,13 @@
 import Foundation
 
+/// Abstraction for basic storage operations.
+///
+/// Conforming types persist and retrieve values described by a ``StorageKey``.
 public protocol StorageProviding: Sendable {
+    /// Stores a value for the given key.
     func set<Value>(_ value: Value, for key: StorageKey<Value>) async throws
+    /// Retrieves a value for the given key.
     func get<Value>(_ key: StorageKey<Value>) async throws -> Value
+    /// Removes a value for the given key.
     func remove<Value>(_ key: StorageKey<Value>) async throws
 }
diff --git a/Sources/LocalData/Protocols/TransformingMigration.swift b/Sources/LocalData/Protocols/TransformingMigration.swift
index b063ba3..5ad6913 100644
--- a/Sources/LocalData/Protocols/TransformingMigration.swift
+++ b/Sources/LocalData/Protocols/TransformingMigration.swift
@@ -1,9 +1,12 @@
 import Foundation
 
-/// Migration protocol that supports data transformation during migration.
+/// Migration protocol that transforms a source value into a destination value.
 public protocol TransformingMigration: StorageMigration {
+    /// The value type stored at the source key.
     associatedtype SourceValue: Codable & Sendable
 
+    /// The source key to read from during migration.
     var sourceKey: StorageKey<SourceValue> { get }
+    /// Transforms a source value into the destination value type.
     func transform(_ source: SourceValue) async throws -> Value
 }
diff --git a/Sources/LocalData/Services/StorageRouter.swift b/Sources/LocalData/Services/StorageRouter.swift
index 741b5c2..1df9bca 100644
--- a/Sources/LocalData/Services/StorageRouter.swift
+++ b/Sources/LocalData/Services/StorageRouter.swift
@@ -4,6 +4,7 @@ import Foundation
 /// Uses specialized helper actors for each storage domain.
 public actor StorageRouter: StorageProviding {
     
+    /// Shared router instance for app-wide storage access.
     public static let shared = StorageRouter()
     
     private var catalogRegistries: [String: [AnyStorageKey]] = [:]
@@ -16,9 +17,10 @@ public actor StorageRouter: StorageProviding {
     private let defaults: UserDefaultsHelper
     private let sync: SyncHelper
     
-    /// Initialize a new StorageRouter.
-    /// Internal for testing isolation via @testable import.
-    /// Consumers should use the `shared` singleton.
+    /// Initializes a new router with injected helpers.
+    ///
+    /// - Important: Internal for testing isolation via `@testable import`.
+    ///             Production code should use ``StorageRouter/shared``.
     internal init(
         keychain: KeychainStoring = KeychainHelper.shared,
         encryption: EncryptionHelper = .shared,
@@ -111,7 +113,7 @@ public actor StorageRouter: StorageProviding {
         catalogRegistries
     }
     
-    /// Returns all currently registered storage keys.
+    /// Returns all currently registered storage keys as a flat list.
     public func allRegisteredEntries() -> [AnyStorageKey] {
         Array(registeredKeys.values)
     }
diff --git a/Sources/LocalData/Utilities/DeviceInfo.swift b/Sources/LocalData/Utilities/DeviceInfo.swift
index 886637a..af594b3 100644
--- a/Sources/LocalData/Utilities/DeviceInfo.swift
+++ b/Sources/LocalData/Utilities/DeviceInfo.swift
@@ -9,11 +9,16 @@ import WatchKit
 
 /// Device information for migration context.
 public struct DeviceInfo: Sendable {
+    /// Current platform (iOS, watchOS, unknown).
     public let platform: Platform
+    /// OS version string.
     public let systemVersion: String
+    /// Device model identifier or marketing name.
     public let model: String
+    /// Whether the device is a simulator.
     public let isSimulator: Bool
 
+    /// Current device info derived from the running environment.
     public static let current = DeviceInfo()
 
     private init() {
@@ -34,6 +39,7 @@ public struct DeviceInfo: Sendable {
         self.isSimulator = ProcessInfo.processInfo.environment["SIMULATOR_DEVICE_NAME"] != nil
     }
 
+    /// Creates a custom device info instance (useful for tests).
     public init(platform: Platform, systemVersion: String, model: String, isSimulator: Bool) {
         self.platform = platform
         self.systemVersion = systemVersion
diff --git a/Sources/LocalData/Utilities/MigrationUtils.swift b/Sources/LocalData/Utilities/MigrationUtils.swift
index e7c312d..e8588a4 100644
--- a/Sources/LocalData/Utilities/MigrationUtils.swift
+++ b/Sources/LocalData/Utilities/MigrationUtils.swift
@@ -2,15 +2,18 @@ import Foundation
 
 /// Utilities for common migration operations.
 public enum MigrationUtils {
+    /// Returns `true` if a value can be transformed between the given types.
     public static func canTransform<T, U>(from: T.Type, to: U.Type) -> Bool {
         if T.self is U.Type { return true }
         return T.self == String.self || U.self == String.self
     }
 
+    /// Estimates the size of a data payload in bytes.
     public static func estimatedSize(for data: Data) -> UInt64 {
         UInt64(data.count)
     }
 
+    /// Validates that source and destination descriptors are compatible.
     public static func validateCompatibility(
         source: StorageKeyDescriptor,
         destination: StorageKeyDescriptor
diff --git a/Sources/LocalData/Utilities/Platform.swift b/Sources/LocalData/Utilities/Platform.swift
index cc3dfc4..dbee813 100644
--- a/Sources/LocalData/Utilities/Platform.swift
+++ b/Sources/LocalData/Utilities/Platform.swift
@@ -1,7 +1,11 @@
 import Foundation
 
+/// Supported runtime platforms for storage availability checks.
 public enum Platform: String, CaseIterable, Sendable {
+    /// iOS platform.
     case iOS = "iOS"
+    /// watchOS platform.
     case watchOS = "watchOS"
+    /// Unknown or unsupported platform.
     case unknown = "unknown"
 }
diff --git a/Sources/LocalData/Utilities/SystemInfo.swift b/Sources/LocalData/Utilities/SystemInfo.swift
index 83afece..7e5314c 100644
--- a/Sources/LocalData/Utilities/SystemInfo.swift
+++ b/Sources/LocalData/Utilities/SystemInfo.swift
@@ -2,10 +2,14 @@ import Foundation
 
 /// System information for migration context.
 public struct SystemInfo: Sendable {
+    /// Free disk space in bytes.
     public let availableDiskSpace: UInt64
+    /// Physical memory in bytes.
     public let availableMemory: UInt64
+    /// Whether Low Power Mode is enabled.
     public let isLowPowerModeEnabled: Bool
 
+    /// Current system info derived from the running environment.
     public static let current = SystemInfo()
 
     private init() {