Senior Full Stack Engineer (AI Agents, Fintech)

melyn builds a platform for First Nations communities across Canada. The Senior Full Stack Engineer will develop reliable financial systems and evolve the platform’s AI assistant into a secure, multi-agent system with strict tenant isolation, auditability, and human approval for risky actions.

Responsibilities:

• Build and improve the finance side of the platform: funding tracking, budgets, reconciliation and financial reporting
• Make sure every financial record is accurate and safe: clear audit trails, safe retries, numbers that always match
• Evolve the chat assistant from workflow plus retrieval into a multi agent system spanning every module, including finance
• Define how each module's agent is bounded: tools it can call, data it can see, and hard limits on what it can do without human approval (especially anything that changes financial records)
• Build the orchestration layer for handoffs across modules, with state, retries and memory across turns
• Build the guardrails: input and output checks, prompt injection defence, PII and financial data handling
• Treat every tool call as a security boundary: least privilege, audit logs of what the agent read and did, safe handling of secrets
• Improve retrieval so answers are grounded in the Nation's own records, and the assistant says "I don't know" rather than making up a number
• Build the evaluation setup: measure false actions and unsupported answers against clear thresholds, under strict tenant isolation
• Extend the chat UI in Next.js: streaming, tool call status, approvals for risky actions, a clear picture of what the agent did and why
• Work with the engineering lead to shape what gets built, review code, and help the team build with LLMs