420543c89e
- Switch transport to streamable_http (matches solve_task.py) - Add _persistent_client global to reuse MultiServerMCPClient across calls - Add exponential backoff 15→30→60→120→240s on 429 responses - Add _INTER_CALL_DELAY=1.5s between consecutive MCP calls to prevent burst - Add _is_429() helper for clean 429 detection - Recreate client on non-429 errors to recover from stale sessions Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>