Senior Python Backend Engineer for Secure CI

We're building an options-market analytics web app: Python 3.12, FastAPI, async SQLAlchemy, PostgreSQL 16, pytest, GitHub Actions and Playwright. The app is read-only analytics. There's no trading in this work, and you will never handle production data, credentials or money. We need an experienced engineer to complete our current release stage (Stage 0) from start to finish: implement the remaining fixes, make every test and CI check pass, and get each change accepted through our review process, ready for production. What you'll deliver (all designs and plans already exist and are reviewed) Data-pipeline correctness fixes: complete, correctly timestamped market-data capture and storage, with missing data failing closed and never filled in. Single-writer lease: a PostgreSQL-based lease so only one process writes at a time. Capture-timing evidence: pytest fixtures and plugins gated to exact test files, with byte-identical behavior for every other suite, covering full test runs with real PostgreSQL, restart and parity checks. A secure evidence-publishing guard and outer test harness: blocks by default across every output channel (stdout and stderr, logs, exceptions, artifacts and files), with fixed error codes, crash-safe capture, and sealing and quarantine states. A default-deny metadata reader: an allow-listed path and field reader whose output passes schema validation. Uptime checks and feature flags for safe rollout. Regression tests for every fix, each failing on the old code and passing on the new. Definition of done: every Stage 0 change is merged through our gated process, passes full CI (SQLite plus real PostgreSQL 16), and is accepted by independent review, with no checks weakened. How we work (please read) Tests first, always. Every change goes through a pull request, CI and independent review. You work on feature branches only. The main branch is protected, and deploys run through our own gated process; you never deploy. Access is limited to the GitHub repository. There's no access to servers, cloud consoles, secrets or production. You follow our written engineering rules, including small reviewable changes and no secrets in any output. Clear daily written updates. An NDA and IP assignment are required. Must have 5+ years of professional Python, including FastAPI and async SQLAlchemy. Strong pytest skills: fixtures, plugins, conftest and collection hooks. GitHub Actions CI experience. PostgreSQL experience, including locks and leases, migrations and data integrity. Secure-coding mindset: least privilege, no secrets in logs, fail-closed design. Nice to have Time-series or market-data pipelines. JSON Schema validation. Hypothesis or property-based testing. Experience building audit or compliance tooling. Fintech experience.