Software Engineer - Fully Remote

Role OverviewMercor 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 MesonContract, task-based work paid at $130 per approved task, performed remotely in Mercor Studio.Key ResponsibilitiesSelect 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 solutionExplore the repository until you genuinely understand the subsystem in question, including the relevant PR or issue historyRewrite the task's question so it defeats frontier coding agents while remaining well-defined and fairly answerableAdjust rubrics and foils so they reward correct reasoning and reject plausible-but-wrong answersRun the full validation loop in Studio — Check, Golden, Run, Analyze — and iterate until every stage passesDocument your work in the task README and submit for expert review, addressing reviewer feedback on returned tasksIdeal Qualifications3+ years of professional software engineering experience, with substantial production PythonDemonstrated ability to navigate a large, unfamiliar Python codebase and explain how it behaves at runtime — not just what the source saysFluency in Python internals that matter in real systems: import machinery, descriptors and metaclasses, async and event loops, packaging, and C-extension boundariesExperience 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 productComfortable with git at commit level, containerized environments, and command-line toolingWorking DetailsFully remote and asynchronous, with expert team leads across US, India, and Nigeria time zonesWork is performed in Mercor Studio; time is tracked with Insightful, and platform access is provisioned through OktaOnboarding 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 grantedPayment is per approved task; every task is reviewed by a second engineer and a super reviewer before acceptanceJ-18808-Ljbffr