Desktop sessions could show MCP configuration in the UI while the CLI SDK child process still started cold on the first user message. Start eligible desktop chat sessions as soon as their websocket is connected, keep init metadata cached but muted, and wait briefly for MCP startup in SDK print mode so turn one sees the tools.
Constraint: Desktop wraps the existing CLI SDK bridge rather than owning MCP startup directly.
Rejected: Prewarm every restored tab | synthetic tabs such as settings would start unnecessary CLI subprocesses.
Confidence: high
Scope-risk: moderate
Directive: Do not remove the synthetic-tab guard without validating restored settings and scheduled-task tabs in the browser.
Tested: bun test src/server/__tests__/conversations.test.ts src/server/__tests__/conversation-service.test.ts src/server/__tests__/mcp.test.ts
Tested: cd desktop && bun run test -- chatStore.test.ts mcpSettings.test.tsx
Tested: cd desktop && bun run lint
Tested: cd desktop && bun run build
Tested: agent-browser E2E new session prewarm plus first message reuse with mock CLI
Not-tested: Full desktop Vitest suite still has pre-existing English-vs-Chinese copy assertion failures.
Desktop-managed sessions were blocking the first visible token on slow or failing
regular MCP connections, which made the UI feel much slower than direct bin runs.
This keeps partial assistant streaming enabled for desktop sessions and moves
regular MCP connection work off the critical path only for sdk-url startup.
Constraint: Desktop sdk-url sessions must preserve chat responsiveness even when local MCP endpoints fail or hang
Rejected: Leave MCP startup fully blocking in sdk-url mode | first visible token stayed several seconds behind direct CLI runs
Confidence: high
Scope-risk: moderate
Reversibility: clean
Directive: Keep blocking MCP startup for plain -p sessions unless you re-measure first-turn latency and tool availability tradeoffs
Tested: bun test src/server/__tests__/conversation-service.test.ts src/server/__tests__/conversations.test.ts; same-prompt timing comparison for direct bin vs sdk-url session path
Not-tested: Immediate first-turn availability of slow regular MCP tools in desktop sdk-url sessions
Bypass all three gating layers (compile-time feature flag, subscription
check, GrowthBook remote config) and replace Anthropic's private native
modules (@ant/computer-use-swift, @ant/computer-use-input) with a Python
bridge using pyautogui + mss + pyobjc. Works on any macOS with any
Anthropic-protocol compatible model.
