Comprehensive code audit: decompose large files, remove V25Features flags, fix identity key persistence, add DI support

- Decompose GroupSession.cs (1610 lines) into 8 partial class files by region
- Decompose DeviceManager.cs (992 lines) into 5 partial class files by region
- Decompose LibEmiddleClient.cs (1344 lines) into 8 partial class files by region
- Remove all V25Features feature flags and FeatureFlags.cs — all features always-on
- Remove IV25FeaturesBuilder, V25FeaturesBuilder, WithV25Features, EnableStableBeta from builder system
- Remove enableAdvancedGroupManagement constructor param from GroupSession; advanced management always enabled
- Fix LoadOrGenerateIdentityKey to persist/load via CryptoProvider with scoped key IDs (fixes multi-client key collision)
- Add ILibEmiddleClient interface and LibEmiddleServiceCollectionExtensions for DI registration
- Fix CreateGroupAsync to route through SessionManager.CreateSessionAsync for consistency
- Fix SendChatMessageAsync to delegate to SessionManager.GetOrCreateChatSessionAsync
- Add SessionManager.GetOrCreateChatSessionAsync to avoid duplicate session creation
- SEC-007: Add MessageRecord.SecureWipe() to zero sensitive bytes on history eviction
- Always create LibEmiddleDiagnostics (no EnableHealthMonitoring gate)
- Remove FeatureFlagsStatus from DiagnosticReport; remove PopulateFeatureFlagsStatus
- Add Microsoft.Extensions.DependencyInjection.Abstractions 9.0.4 package reference
- Add new test files: StubInfrastructureTests, SessionManagerBundleTests, and others
- Clean up v2.5 doc comment labels and Requires V25Features references throughout

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: rbenzing

.gitignore

@@ -252,6 +252,7 @@ orleans.codegen.cs
 
 # RIA/Silverlight projects
 Generated_Code/
+orchestration/
 
 # Backup & report files from converting an old project file
 # to a newer Visual Studio version. Backup files are not needed,

CHANGELOG.md

@@ -8,22 +8,26 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 
 ### Added
-- Nothing yet
+- **Bundle Caching**: `SessionPersistenceManager` now includes `SaveKeyBundleAsync()` and `LoadKeyBundleByIdentityKeyAsync()` for caching recipient X3DH key bundles to disk, enabling session creation from a bare identity key after the first exchange
+- **Password KDF Overload**: New `CryptoProvider.DeriveKeyFromPassword(string password, byte[] salt)` overload accepting a caller-supplied random salt for non-deterministic key derivation
+- **Shared Key Conversion Helper**: New `LibEmiddle.Core.KeyConversion.ConvertEd25519PublicKeyToX25519()` consolidating duplicate Ed25519→X25519 conversion logic previously spread across `DeviceManager` and `DeviceLinkingService`
+- **Unit Tests**: Added 60+ new unit tests covering `MessageSigning`, `AES` detached encryption, `Nonce` thread-safety, `EnhancedFileStorageProvider`, `PostQuantumCrypto`, stub infrastructure visibility, and `SessionManager` bundle/group session paths
 
 ### Changed
-- Nothing yet
-
-### Deprecated
-- Nothing yet
-
-### Removed
-- Nothing yet
+- **Password Key Derivation**: Migrated from HKDF with a fixed static salt to **Argon2id** (via libsodium's `crypto_pwhash`) for memory-hard password-based key derivation (64 MB, 2 passes). The deterministic overload uses a fixed application-specific salt; the new overload accepts a random salt
+- **CreateSessionAsync Bundle Handling**: Now accepts a serialized `X3DHPublicBundle` as UTF-8 JSON bytes and automatically caches the bundle via `SaveKeyBundleAsync()` for future bare-key lookups
+- **GetOrCreateRecipientBundleAsync**: Replaced stub implementation (threw `InvalidOperationException`) with a proper lookup using the new `LoadKeyBundleByIdentityKeyAsync()`. Throws `ArgumentException` with a descriptive message if no cached bundle is found
+- **Batch Serialization**: Replaced reflection-based `MakeGenericMethod` in `BatchAsync` with the BCL's `JsonSerializer.Serialize(object?, Type, JsonSerializerOptions?)` overload, eliminating runtime reflection
+- **Disposal Guards**: Changed all `bool _disposed` fields to `volatile bool _disposed` across all `IDisposable` classes for correct thread-safe disposal checks
+- **Timer Callback**: `EnhancedFileStorageProvider.CleanupExpiredItems` refactored to `async void` + inner `DoCleanupExpiredItemsAsync()` pattern, eliminating the `.Wait()` call that could deadlock on synchronization contexts
 
 ### Fixed
-- Nothing yet
+- **AES-GCM Detached Decryption**: Corrected the P/Invoke signature for `crypto_aead_aes256gcm_decrypt_detached_afternm` in `Sodium.cs` — removed the erroneous `out ulong mlen_p` second parameter that does not exist in this libsodium entry point, which was causing all AES-GCM detached decryption to fail
+- **MessageSigning Verification**: Fixed reversed argument order in `Sodium.SignVerifyDetached()` call inside `MessageSigning.VerifyObject<T>()` — signature and message bytes were swapped, causing all signature verification to fail
+- **Session File Integrity**: `EncryptAndSaveSessionAsync` now checks the return value of `StoreKeyAsync` and removes the orphaned session file if the encryption key cannot be persisted
 
 ### Security
-- Nothing yet
+- **Argon2id Password Hardening**: The Argon2id KDF (64 MB memory, 2 iterations) is orders of magnitude more resistant to GPU/ASIC brute-force attacks than the previous HKDF-with-fixed-salt approach
 
 ## [2.5.1] - 2025-12-22
 

LibEmiddle.Abstractions/IChatSession.cs

@@ -95,21 +95,21 @@ public interface IChatSession : ISession
         /// </summary>
         bool IsValid();
 
-        // --- v2.5 Enhanced Methods (Optional - requires V25Features.EnableAsyncMessageStreams) ---
+        // --- Async Stream Methods ---
 
         /// <summary>
-        /// Gets an async stream of incoming messages (v2.5).
+        /// Gets an async stream of incoming messages.
         /// This runs in parallel with the MessageReceived event.
-        /// Requires V25Features.EnableAsyncMessageStreams = true.
+        /// Requires async streaming to be enabled when the session is created.
         /// </summary>
         /// <param name="cancellationToken">Token to cancel the stream.</param>
         /// <returns>Async enumerable of message received events.</returns>
         IAsyncEnumerable<MessageReceivedEventArgs> GetMessageStreamAsync(CancellationToken cancellationToken = default);
 
         /// <summary>
-        /// Gets an async stream of incoming messages with optional filtering (v2.5).
+        /// Gets an async stream of incoming messages with optional filtering.
         /// This runs in parallel with the MessageReceived event.
-        /// Requires V25Features.EnableAsyncMessageStreams = true.
+        /// Requires async streaming to be enabled when the session is created.
         /// </summary>
         /// <param name="messageFilter">Optional filter predicate for messages.</param>
         /// <param name="cancellationToken">Token to cancel the stream.</param>
@@ -118,10 +118,11 @@ IAsyncEnumerable<MessageReceivedEventArgs> GetFilteredMessageStreamAsync(
             Func<MessageReceivedEventArgs, bool>? messageFilter = null,
             CancellationToken cancellationToken = default);
 
+        // --- Message Batching Methods ---
+
         /// <summary>
-        /// Sends a message with optional batching (v2.5).
+        /// Sends a message with optional batching.
         /// If batching is enabled, the message may be queued for later transmission.
-        /// Requires V25Features.EnableMessageBatching = true.
         /// </summary>
         /// <param name="message">The plaintext message to send.</param>
         /// <param name="priority">Priority level for batching.</param>
@@ -130,15 +131,15 @@ IAsyncEnumerable<MessageReceivedEventArgs> GetFilteredMessageStreamAsync(
         Task<bool> SendMessageAsync(string message, MessagePriority priority, bool forceSend = false);
 
         /// <summary>
-        /// Gets the current message batcher if batching is enabled (v2.5).
-        /// Requires V25Features.EnableMessageBatching = true.
+        /// Gets the current message batcher if batching is enabled.
+        /// Returns null if batching is not configured for this session.
         /// </summary>
         /// <returns>The message batcher, or null if batching is not enabled.</returns>
         IMessageBatcher? GetMessageBatcher();
 
         /// <summary>
-        /// Forces any pending batched messages to be sent immediately (v2.5).
-        /// Requires V25Features.EnableMessageBatching = true.
+        /// Forces any pending batched messages to be sent immediately.
+        /// Returns 0 if batching is not configured for this session.
         /// </summary>
         /// <returns>The number of messages flushed.</returns>
         Task<int> FlushPendingMessagesAsync();

LibEmiddle.Abstractions/IGroupSession.cs

@@ -145,26 +145,23 @@ public interface IGroupSession : ISession
     /// <exception cref="ArgumentException">Thrown when serializedState is null, empty, or invalid</exception>
     Task<bool> RestoreSerializedStateAsync(string serializedState);
 
-    // --- v2.5 Enhanced Group Management Methods (Optional - requires V25Features.EnableAdvancedGroupManagement) ---
+    // --- Enhanced Group Management Methods ---
 
     /// <summary>
-    /// Gets all members of the group with their roles and permissions (v2.5).
-    /// Requires V25Features.EnableAdvancedGroupManagement = true.
+    /// Gets all members of the group with their roles and permissions.
     /// </summary>
     /// <returns>Collection of group members with enhanced information.</returns>
     Task<IReadOnlyCollection<GroupMember>> GetMembersAsync();
 
     /// <summary>
-    /// Gets a specific member by their public key (v2.5).
-    /// Requires V25Features.EnableAdvancedGroupManagement = true.
+    /// Gets a specific member by their public key.
     /// </summary>
     /// <param name="memberPublicKey">The public key of the member to find.</param>
     /// <returns>The group member, or null if not found.</returns>
     Task<GroupMember?> GetMemberAsync(byte[] memberPublicKey);
 
     /// <summary>
-    /// Changes a member's role in the group (v2.5).
-    /// Requires V25Features.EnableAdvancedGroupManagement = true and appropriate permissions.
+    /// Changes a member's role in the group.
     /// </summary>
     /// <param name="memberPublicKey">The public key of the member.</param>
     /// <param name="newRole">The new role to assign.</param>
@@ -173,8 +170,7 @@ public interface IGroupSession : ISession
     Task<bool> ChangeMemberRoleAsync(byte[] memberPublicKey, MemberRole newRole);
 
     /// <summary>
-    /// Grants specific permissions to a member (v2.5).
-    /// Requires V25Features.EnableAdvancedGroupManagement = true and appropriate permissions.
+    /// Grants specific permissions to a member.
     /// </summary>
     /// <param name="memberPublicKey">The public key of the member.</param>
     /// <param name="permissions">The permissions to grant.</param>
@@ -183,8 +179,7 @@ public interface IGroupSession : ISession
     Task<bool> GrantPermissionsAsync(byte[] memberPublicKey, IEnumerable<GroupPermission> permissions);
 
     /// <summary>
-    /// Revokes specific permissions from a member (v2.5).
-    /// Requires V25Features.EnableAdvancedGroupManagement = true and appropriate permissions.
+    /// Revokes specific permissions from a member.
     /// </summary>
     /// <param name="memberPublicKey">The public key of the member.</param>
     /// <param name="permissions">The permissions to revoke.</param>
@@ -193,8 +188,7 @@ public interface IGroupSession : ISession
     Task<bool> RevokePermissionsAsync(byte[] memberPublicKey, IEnumerable<GroupPermission> permissions);
 
     /// <summary>
-    /// Mutes a member for a specified duration (v2.5).
-    /// Requires V25Features.EnableAdvancedGroupManagement = true and ModerateMembers permission.
+    /// Mutes a member for a specified duration.
     /// </summary>
     /// <param name="memberPublicKey">The public key of the member to mute.</param>
     /// <param name="duration">How long to mute the member for.</param>
@@ -204,17 +198,15 @@ public interface IGroupSession : ISession
     Task<bool> MuteMemberAsync(byte[] memberPublicKey, TimeSpan duration, string? reason = null);
 
     /// <summary>
-    /// Unmutes a member (v2.5).
-    /// Requires V25Features.EnableAdvancedGroupManagement = true and ModerateMembers permission.
+    /// Unmutes a member.
     /// </summary>
     /// <param name="memberPublicKey">The public key of the member to unmute.</param>
     /// <returns>True if the member was unmuted successfully.</returns>
     /// <exception cref="UnauthorizedAccessException">Thrown when the current user lacks permission.</exception>
     Task<bool> UnmuteMemberAsync(byte[] memberPublicKey);
 
     /// <summary>
-    /// Sets metadata for a group member (v2.5).
-    /// Requires V25Features.EnableAdvancedGroupManagement = true and appropriate permissions.
+    /// Sets metadata for a group member.
     /// </summary>
     /// <param name="memberPublicKey">The public key of the member.</param>
     /// <param name="key">The metadata key.</param>
@@ -224,8 +216,7 @@ public interface IGroupSession : ISession
     Task<bool> SetMemberMetadataAsync(byte[] memberPublicKey, string key, string value);
 
     /// <summary>
-    /// Creates an invitation code for the group (v2.5).
-    /// Requires V25Features.EnableAdvancedGroupManagement = true and AddMember permission.
+    /// Creates an invitation code for the group.
     /// </summary>
     /// <param name="expiresIn">How long the invitation should be valid for.</param>
     /// <param name="maxUses">Maximum number of times the invitation can be used (null for unlimited).</param>
@@ -235,26 +226,23 @@ public interface IGroupSession : ISession
     Task<string> CreateInvitationAsync(TimeSpan expiresIn, int? maxUses = null, MemberRole defaultRole = MemberRole.Member);
 
     /// <summary>
-    /// Revokes an invitation code (v2.5).
-    /// Requires V25Features.EnableAdvancedGroupManagement = true and AddMember permission.
+    /// Revokes an invitation code.
     /// </summary>
     /// <param name="invitationCode">The invitation code to revoke.</param>
     /// <returns>True if the invitation was revoked successfully.</returns>
     /// <exception cref="UnauthorizedAccessException">Thrown when the current user lacks permission.</exception>
     Task<bool> RevokeInvitationAsync(string invitationCode);
 
     /// <summary>
-    /// Joins the group using an invitation code (v2.5).
-    /// Requires V25Features.EnableAdvancedGroupManagement = true.
+    /// Joins the group using an invitation code.
     /// </summary>
     /// <param name="invitationCode">The invitation code to use.</param>
     /// <param name="memberPublicKey">The public key of the new member.</param>
     /// <returns>True if the member joined successfully.</returns>
     Task<bool> JoinWithInvitationAsync(string invitationCode, byte[] memberPublicKey);
 
     /// <summary>
-    /// Gets group statistics and insights (v2.5).
-    /// Requires V25Features.EnableAdvancedGroupManagement = true.
+    /// Gets group statistics and insights.
     /// </summary>
     /// <returns>Group statistics including member activity, message counts, etc.</returns>
     Task<GroupStatistics> GetGroupStatisticsAsync();

LibEmiddle.Domain/Diagnostics/DiagnosticReport.cs

@@ -58,11 +58,6 @@ public class DiagnosticReport
         /// </summary>
         public PerformanceStatistics Performance { get; set; } = new();
 
-        /// <summary>
-        /// Feature flags status.
-        /// </summary>
-        public FeatureFlagsStatus Features { get; set; } = new();
-
         /// <summary>
         /// Security audit information.
         /// </summary>
@@ -140,23 +135,6 @@ public class PerformanceStatistics
         public TimeSpan Uptime { get; set; }
     }
 
-    /// <summary>
-    /// Feature flags status for diagnostic report.
-    /// </summary>
-    public class FeatureFlagsStatus
-    {
-        public bool AsyncMessageStreams { get; set; }
-        public bool MessageBatching { get; set; }
-        public bool AdvancedGroupManagement { get; set; }
-        public bool HealthMonitoring { get; set; }
-        public bool FluentBuilder { get; set; }
-        public bool PluggableStorage { get; set; }
-        public bool PostQuantumPreparation { get; set; }
-        public bool WebRTCTransport { get; set; }
-        public bool ConnectionPooling { get; set; }
-        public bool SessionBackup { get; set; }
-    }
-
     /// <summary>
     /// Security audit information for diagnostic report.
     /// </summary>