Senior AI Software Engineer

Senior Software AI Engineer — Agentic Platforms Full-Time, Permanent | Downtown Toronto | Hybrid Our client, a global enterprise, is building an internal AI platform — a multi-tenant, model-agnostic environment spanning a web app, a desktop agent client, an AI App Store, and a skills/tool ecosystem over the company's knowledge. They're looking for a Senior AI Engineer to help design and build the agent infrastructure at the core of it: orchestration engines, the desktop agent harness, tool/skill registries, and the policy layers that make it all safe to run at enterprise scale. What you'll do • Build and extend multi-agent orchestration (LangGraph, Microsoft Agent Framework, Deep Agents) — stateful graphs, checkpointing, sub-agents, human-in-the-loop, long-running execution. • Work directly with frontier LLM SDKs at the agent-loop level (Anthropic, OpenAI, Google) — not just chat completions. • Own the model-agnostic routing layer: provider routing, cost/token accounting, graceful degradation as models churn. • Build MCP integration, sandboxing/process isolation, and a permission system (ALLOW/ASK/DENY) enforced across runtimes. • Build retrieval, grounding, and citation pipelines that hold up in production. • Build eval infrastructure — regression gates, tracing, and diagnosability for agent failures. What we need • 7+ years building production software, with recent, substantial work on LLM-based systems used by real users. • Strong TypeScript (Node.js, async, strict typing) and working proficiency in Python (FastAPI, Pydantic). • Production depth in LangGraph, Microsoft Agent Framework, or Deep Agents. • Direct experience with at least one frontier provider SDK at the agent-loop level. • Hands-on with tool calling, MCP (or comparable), streaming (SSE/WebSocket), structured output. Nice to have • Google ADK, Semantic Kernel, CrewAI, LlamaIndex, AutoGen, Pydantic AI, Mastra. • Sandboxing/isolation experience (gVisor, nsjail, Firecracker, Seatbelt, Bubblewrap). • Electron/desktop app engineering, vector search, regulated-industry experience (insurance, banking, financial services). #J-18808-Ljbffr