Unified Data Access Layer

This module provides a unified interface for accessing message data from different sources:

• DexieMessageDataSource: Local IndexedDB storage for regular chat messages
• AgentMessageDataSource: Backend IPC storage for agent session messages

Architecture

dbService (Facade)
    ├── Determines data source based on topicId
    ├── Routes to DexieMessageDataSource (regular chats)
    └── Routes to AgentMessageDataSource (agent sessions)

Usage

import { dbService } from '@renderer/services/db'

// Fetch messages (automatically routes to correct source)
const { messages, blocks } = await dbService.fetchMessages(topicId)

// Save a message exchange
await dbService.persistExchange(topicId, {
  user: { message: userMsg, blocks: userBlocks },
  assistant: { message: assistantMsg, blocks: assistantBlocks }
})

// Append a single message
await dbService.appendMessage(topicId, message, blocks)

// Check if topic exists
const exists = await dbService.topicExists(topicId)

Topic ID Convention

• Regular chat topics: Any string ID (e.g., "uuid-1234-5678")
• Agent session topics: Prefixed with "agent-session:" (e.g., "agent-session:session-123")

Key Features

1. Transparent Routing: The facade automatically routes to the appropriate data source
2. Consistent API: Same methods work for both regular chats and agent sessions
3. Type Safety: Full TypeScript support with proper interfaces
4. Error Handling: Comprehensive error logging and propagation
5. Extensibility: Easy to add new data sources (e.g., cloud storage)

Implementation Status

DexieMessageDataSource ✅

• Full CRUD operations for messages and blocks
• Transaction support
• File cleanup on deletion
• Redux state updates

AgentMessageDataSource ✅

• Fetch messages from backend
• Persist message exchanges
• Limited update/delete operations (by design)
• IPC communication with backend

Migration Guide

Before (Direct DB access):

// In thunks
if (isAgentSessionTopicId(topicId)) {
  // Special handling for agent sessions
  const messages = await window.electron.ipcRenderer.invoke(...)
} else {
  // Regular DB access
  const topic = await db.topics.get(topicId)
}

After (Unified access):

// In thunks
const { messages, blocks } = await dbService.fetchMessages(topicId)
// No need to check topic type!

Next Steps

Phase 2: Update Redux thunks to use dbService Phase 3: Update components to use unified hooks Phase 4: Remove AgentSessionMessages component