Backend developer Jobs in Menifee, CA

## **1\. Role Overview** Mercor is seeking experienced **Python engineers** to build the dataset that teaches AI agents to reason about real codebases. Codebase Q&A is a reinforcement-learning environment for training AI agents to explore and reason about software repositories they have never seen before. You will build difficult codebase-exploration tasks: high-level engineering questions about production Python repositories that cannot be answered by reading a single file, and that require runtime evidence to resolve — the kind of question a senior engineer answers by actually investigating the system. This track works on widely deployed Python codebases including **Django, Twisted, Scrapy, SymPy, mypy, pip, coverage.py, mitmproxy, Certbot, Tornado, Werkzeug, sqlfluff and Meson**. Contract, task-based work paid at **$130 per approved task**, performed remotely in Mercor Studio. ## **2\. Key Responsibilities** - Select tasks from a pre-validated pool of Python repositories, each pinned to a specific git commit and arriving with an engineering question, positive and negative rubrics, foils, and a golden solution - Explore the repository until you genuinely understand the subsystem in question, including the relevant PR or issue history - Rewrite the task's question so it defeats frontier coding agents while remaining well-defined and fairly answerable - Adjust rubrics and foils so they reward correct reasoning and reject plausible-but-wrong answers - Run the full validation loop in Studio — Check, Golden, Run, Analyze — and iterate until every stage passes - Document your work in the task README and submit for expert review, addressing reviewer feedback on returned tasks ## **3\. Ideal Qualifications** - 3+ years of professional software engineering experience, with substantial production Python - Demonstrated ability to navigate a large, unfamiliar Python codebase and explain how it behaves at runtime — not just what the source says - Fluency in Python internals that matter in real systems: import machinery, descriptors and metaclasses, async and event loops, packaging, and C-extension boundaries - Experience with web frameworks, developer tooling, type checkers, or scientific/numeric libraries is highly relevant — the task mix is weighted toward architecture and system design (41%) and code onboarding (31%) - Precise written English: the questions and rubrics you write are the product - Comfortable with git at commit level, containerized environments, and command-line tooling ## **4\. Working Details** - Fully remote and asynchronous, with expert team leads across US, India, and Nigeria time zones - Work is performed in Mercor Studio; time is tracked with Insightful, and platform access is provisioned through Okta - Onboarding requires identity verification, a background check, signed Terms of Work and CIIAA, a tax form, and passing a short calibration quiz before task access is granted - Payment is per approved task; every task is reviewed by a second engineer and a super reviewer before acceptance ## **5\. Application Process** - Submit your resume or relevant technical background to get started - Qualified applicants may be asked to complete a brief technical assessment or provide additional information