[REFACTOR] Split large Claude router into smaller modules

[Tsukieomie]

Code Quality: Refactor Large Router File

Severity: MEDIUM (maintainability)
Location: src/main/lib/trpc/routers/claude.ts (1,800+ lines)

Description

The Claude router is 1,800+ lines and handles multiple concerns, making it hard to test, maintain, and debug.

Current Responsibilities

• Message streaming
• MCP server configuration
• Session management
• Tool approval/gating
• File path resolution
• Cache management
• Error handling

Recommendation

Split into focused modules:

lib/trpc/routers/claude/
├── index.ts              # Main router (exports)
├── message-stream.ts     # Streaming logic
├── mcp-config.ts         # MCP server management
├── session-manager.ts    # Session state & lifecycle
├── tool-approval.ts      # Tool gating & permissions
├── path-resolver.ts      # File path resolution
└── cache.ts              # Caching strategies

Benefits:

• Easier to test individual components
• Better code organization
• Reduces merge conflicts
• Easier to onboard new contributors
• Simpler debugging

Example Structure

index.ts

import { createMessageStream } from './message-stream'
import { getMCPConfig } from './mcp-config'
import { SessionManager } from './session-manager'

export const claudeRouter = router({
  onMessage: createMessageStream(sessionManager, mcpConfig),
  // ... other procedures
})

message-stream.ts

export function createMessageStream(
  sessionManager: SessionManager,
  mcpConfig: MCPConfig
) {
  return publicProcedure
    .input(messageSchema)
    .subscription(async function* ({ input }) {
      // Stream implementation
    })
}

Priority

Medium - Not urgent but would improve maintainability significantly.

Labels: refactor, code-quality