I'm Xinyi Lin — a full-stack software engineer building real-world tools at the intersection of software and healthcare.

I've spent the last two years inside a high-volume cardiology clinic watching clinicians fight their EHR every day, and I build software that tries to do better.

A portfolio-grade EHR demo covering scheduling, clinical charting, billing, document management, and organization/facility administration. Modeled on the workflows I see in a real clinic — not generic CRUD.

• Clinical charting with SOAP progress notes (draft / signed / unsigned states), encounter lifecycle, and a 68-code CPT catalog
• Configurable fee schedules with payer and facility overrides
• Patient timeline that unifies appointments, encounters, medications, and allergies into one chronological view via a shared timeline component
• Security: SSN encryption at rest (Fernet), JWT + HTTP-only refresh cookies, CSRF protection, role-based permissions scoped per facility, and an audit log for sensitive actions
• Typed end-to-end via OpenAPI codegen (drf-spectacular + openapi-typescript)
• Deployed on AWS Amplify (frontend) + Render (backend), with PostgreSQL on Amazon RDS, Cloudflare R2 object storage, and Docker Compose for local dev

🔗 Live demo: careflow.xinyiklin.com — clinician app at clinician.xinyiklin.com, patient portal at patient.xinyiklin.com 💻 Code: github.com/xinyiklin/careflow

RoleFit combines resume tailoring, recruiter-style review, and application tracking in the browser while a small Electron companion manages the local server and AI providers.

• Evidence-grounded AI workflow with prompt-injection fencing, output sanitization, offline adversarial evals, and reviewable edits instead of silent resume rewrites
• Five explicit providers: Claude Code, Codex, and Antigravity through provider-owned CLI sessions, plus OpenAI and Claude APIs with keys encrypted locally by the companion
• Built on the shared Typeset engine — edit the exported page directly, generate a deterministic client-side PDF, and save the structured document as a portable .resume file
• Workday-aware job import with AI distillation, deterministic fallback extraction, duplicate checks, and a fail-closed multi-stage polish/review workflow
• Local application tracker with table and calendar views; no RoleFit account or cloud workspace, and only the inputs required for the selected AI action leave the device

🔗 Product site: rolefit.xinyiklin.com 💻 Code: github.com/xinyiklin/rolefit-ai

A WYSIWYG resume editor built on a from-scratch deterministic typesetting engine — edit the rendered page directly and export a pixel-faithful PDF that the app renders itself. Runs entirely in your browser; your resume never leaves your device.

• From-scratch layout engine (measure → line-break → blocks → layout) shared by the editor, browser print, and a client-side pdf-lib PDF emitter — the editor and the exported PDF render glyph-identically, verified by an automated font-parity suite
• Direct editing on the engine-rendered page: structured document model, inline formatting marks, and real undo/redo with exact caret restoration
• Strict versioned .resume file format with browser autosave, plus print-aware typography — six bundled font families, three of them metrically compatible with Times New Roman, Calibri, and Arial so page count survives a round trip through a word processor
• Engine and editor live as npm workspace packages (@typeset/engine, @typeset/editor) inside the RoleFit AI monorepo, powering both Typeset and RoleFit from one source of truth
• Dockerized and deployed to AWS EC2 (custom domain, HTTPS) via a path-filtered GitHub Actions CI/CD pipeline

🔗 Live app: typeset.xinyiklin.com 💻 Code: github.com/xinyiklin/rolefit-ai — apps/typeset + packages/engine / packages/editor

The tooling behind how I work with coding agents: one-time, idempotent seeding of agent guidance, shared skills, and a delivery workflow across a workspace of independent sibling repositories — without turning that workspace into a parent repo that silently owns every project's instructions.

• Sibling-only ownership model — the workspace root holds no live guidance; each project owns its own AGENTS.md / CLAUDE.md after seeding and is never re-synced against the template source
• Idempotent Node initializers that create only missing files, preserve existing ones, refuse unsafe targets (filesystem root, $HOME, Git-owned workspaces), and roll back only run-owned files on failure
• .gitignore environment policy verified through Git itself rather than by pattern matching — ambiguous or ineffective rules stop for manual review before any write
• Supply-chain-pinned shared skills: every skill pinned by repository, revision, and content SHA-256, with a missing-only installer and drift detection
• Provider-neutral workflow packages (Product Partner → Delivery Lead → Verifier, with explicit approval gates) compiled into deterministic Claude and Codex agent adapters
• Verified on Linux and Windows in CI against a disposable regression suite covering rollback, concurrency, and fail-closed paths

💻 Code: github.com/xinyiklin/machine-bootstrap

Languages: Python, TypeScript, JavaScript, C++, SQL, HTML/CSS

Frontend: React, TypeScript, Vite, React Query, React Router, Tailwind CSS

Backend: Django, Django REST Framework, Node.js, REST APIs, JWT + CSRF auth

Data & Storage: PostgreSQL, Cloudflare R2 / S3-compatible object storage

Desktop & Local Runtime: Electron, loopback Node services, OS-encrypted credential storage

Tooling & Deployment: Git, Docker, npm workspaces (monorepo), AWS (Amplify, RDS, EC2), GitHub Actions CI/CD, GitHub Pages, Cloudflare, Render, ESLint, Prettier, pre-commit hooks

• 🏥 Two years inside a cardiovascular clinic — real exposure to EHR migrations, scheduling bottlenecks, and clinical workflow design
• 🛠 Comfortable across the full stack: schema design, REST APIs, React frontends, auth/security, deployment
• 🌱 Currently going deeper on system design, OpenAPI tooling, and clinical informatics
• 🌐 Bilingual in English and Mandarin Chinese

• 📧 Email: xinyiklin@gmail.com
• 💼 LinkedIn: linkedin.com/in/xinyiklin
• 🧍 Portfolio: xinyiklin.com

Currently exploring early-career and SWE I roles in healthcare tech and full-stack — always open to a coffee chat about clinical software, full-stack architecture, or building tools clinicians actually want to use.