Schwab API Execution Hardening – 2 Week Contract I’m completing a nearly finished Python trading system (“Hyperion”) and need a senior execution-focused engineer for final hardening and validation. This is NOT a strategy build. This is broker execution stabilization. System Context: • Schwab API integration • Cash account only • Single-leg options only • No spreads • No margin • GUI guardrails implemented (contract limits, capital caps, DTE filters, one position per symbol) • 80–90% complete Scope: • Validate OAuth refresh logic • Harden order submission (idempotency, duplicate prevention) • Confirm proper order lifecycle handling • Implement position reconciliation checks • Add structured logging • Support deployment Timeline: 2 weeks max Budget: $1,000 fixed (paid in structured installments) Do NOT apply if: • You have not worked with live brokerage APIs. • You have not handled OAuth lifecycle. • You have only built backtesting systems. Before proceeding, please answer the screening questions below directly. If aligned, we can begin immediately. ] ________________________________________ SCREENING QUESTIONS (REQUIRED) Send these immediately after outreach. 1. How do you implement idempotent order submission in broker APIs? 2. How would you handle OAuth token expiration mid-session? 3. Describe how you reconcile local position state with broker state. 4. What safeguards prevent duplicate order submissions in async systems? 5. How would you structure Live vs Paper trading adapters cleanly? 6. How do you classify and log broker vs auth vs network errors? 7. What risks occur near 0DTE expiration and how Stream