Add chat persistence with multi-session support

[Copilot]

• Review new actionable PR comments and inspect current chat implementation
• Run baseline build/tests to confirm current state before edits
• Investigate unresolved feedback on session creation atomicity and determine minimal fix
• Apply surgical code changes and validate with targeted build/tests
• Run final parallel validation
• Reply to new PR comments with commit hash and screenshot

[Copilot]

Pull request overview

Adds SQLite-backed chat persistence with multi-session support, integrating chat session/message entities into EF Core and updating the MVC chat UI/controller to load, create, rename, delete, and continue persisted conversations.

Changes:

• Added ChatSession and ChatSessionMessage entities, DbSets, relationship mapping, and migration.
• Updated ChatController to load persisted sessions/messages and persist new user/assistant messages.
• Expanded the chat view with a session sidebar, server-rendered persisted messages, and session management actions.

Reviewed changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
LifelogBb/Controllers/ChatController.cs	Adds session-aware chat loading, sending, persistence, rename, create, and delete actions.
LifelogBb/Views/Chat/Index.cshtml	Adds chat sidebar, persisted message hydration, and client-side session actions.
LifelogBb/Models/LifelogBbContext.cs	Registers chat session DbSets and cascade relationship mapping.
LifelogBb/Models/Entities/ChatSession.cs	Adds chat session entity.
LifelogBb/Models/Entities/ChatSessionMessage.cs	Adds persisted chat message entity.
LifelogBb/Models/Chat/ChatViewModel.cs	Extends chat view model with session state.
LifelogBb/Models/Chat/ChatSessionListItem.cs	Adds sidebar session list item model.
LifelogBb/Migrations/20260516065018_ChatPersistence.cs	Creates chat persistence tables and FK/index.
LifelogBb/Migrations/20260516065018_ChatPersistence.Designer.cs	EF migration model snapshot for chat persistence.
LifelogBb/Migrations/LifelogBbContextModelSnapshot.cs	Updates EF model snapshot with chat entities.

Files not reviewed (1)

• LifelogBb/Migrations/20260516065018_ChatPersistence.Designer.cs: Language not supported

[spech66]

@copilot apply changes based on the comments in this thread but don't over engineer the sanitizer. The app is supposed to have input/output in a more or less trusted env (self hosted llm or chat gpt) and instructions are also handled by the user so the risk is very low.

[Copilot]

@copilot apply changes based on the comments in this thread but don't over engineer the sanitizer. The app is supposed to h...

Applied all review fixes in commit 3370628:

• Index: supplied id that doesn't exist now shows an empty chat state instead of silently loading the latest session.
• Send: returns { error: "Session not found." } when a SessionId is posted but the session is gone, instead of creating a duplicate new session.
• SortOrder: replaced the in-memory Max() with a MaxAsync DB query, so concurrent sends to the same chat get monotonically increasing sort orders.
• Context window: capped conversation history sent to the AI at MaxConversationMessages = 20 (last 20 messages).
• Rename: data-session-name on the rename button is now updated in the success callback, so re-renaming shows the current name in the prompt.
• History property: removed from ChatSendRequest — it was never read after session persistence was added.
• XSS: skipped over-engineering per your guidance; innerHTML rendering is kept as-is for the self-hosted trusted environment.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 10 changed files in this pull request and generated 4 comments.

Files not reviewed (1)

• LifelogBb/Migrations/20260516065018_ChatPersistence.Designer.cs: Language not supported

[spech66]

@copilot apply changes based on the comments in this thread

[Copilot]

@copilot apply changes based on the comments in this thread

Implemented in 31e1345.

This updates ChatController.Send to: query only the most recent persisted history messages (instead of loading all), enforce the 20-message cap including the current user message, persist assistant raw text (render markdown only for display), and persist message ordering inside a retryable serializable transaction path to handle concurrent sends safely.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 10 changed files in this pull request and generated 7 comments.

Files not reviewed (1)

• LifelogBb/Migrations/20260516065018_ChatPersistence.Designer.cs: Language not supported