SlipstreamJobs tracks this role from the company's public career site. Apply directly on the employer's site.
Lightsprint (YC P26) is building a collaborative product-development platform for the AI era—a code-aware task board where every task is a real agent session with its own environment, preview URL, and context. The platform combines cloud coding agents, per-task preview environments, and real-time multiplayer collaboration into one integrated system.
As a Senior Software Engineer, you'll join an early-stage team in a product engineer role. You'll talk directly with users to frame problems, design solutions collaboratively, ship end-to-end features, and iterate based on logs and usage data. The team dogfoods relentlessly, building Lightsprint with their own agents.
Key responsibilities include:
- Building LLM brains and optimizing multi-turn prompts to turn non-deterministic agent behavior into trustworthy interfaces
- Solving hard technical problems: real-time multiplayer systems, agent harnesses that orchestrate cloud coding agents, and sandboxes that spin up isolated environments with live previews
- Balancing speed with reliability—the product is infrastructure other teams depend on
- Leveraging agentic tools to multiply your own productivity
- Owning complex, end-to-end features with visible product impact
You'll work across the full stack: TypeScript, relational databases (Postgres), real-time systems, modern frontend frameworks (Next.js, Svelte), and modern DevOps (AWS, Vercel). Strong product sensibility is essential—you care about UX, performance, and polish; you push back when something doesn't feel right; you're comfortable shaping ambiguous problems without a handed-down roadmap.
Nice-to-haves include experience in agent engineering (harnesses, tool-calling, evals, MCP, RAG, context management), real-time/multiplayer/collaborative software design, developer tools or complex B2B SaaS, and a track record of building platforms teams adopt.
