{"id":4004804,"url":"https://alion.io/job/xero-senior-full-stack-engineer-ai-harness","title":"Senior Full Stack Engineer - AI Harness","company":{"id":5206,"name":"Xero","domain":"xero.com","url":"https://alion.io/company/xero","size_band":"1001-5000","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Ashby","truth_index":{"grade":"B","score":81,"open_postings":16,"ghost_share":0.063,"stale_share":0.563,"repost_share":0.063,"time_to_fill_p50_days":33,"computed_at":"2026-11-10T06:52:35Z"}},"role":"Backend","role_family":"Backend","seniority":"senior","employment_type":"full_time","work_mode":"remote","remote_scope":"stated_countries","remote_scope_basis":"posting_text","remote_working_hours":null,"hiring_geo_confidence":"explicit","locations":["Wellington, New Zealand","Auckland, New Zealand"],"countries":["NZ"],"hiring_countries":["NZ"],"hiring_countries_total":1,"salary":null,"salary_estimate":null,"experience_years_min":null,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":".NET","optional":false},{"name":"C#","optional":false},{"name":"LLM Guardrails","optional":false},{"name":"SQL","optional":false},{"name":"Xero","optional":false}],"status":"live","first_seen_at":"2026-11-10T03:25:30Z","employer_posted_date":"2026-11-10","last_verified_at":"2026-11-10T23:42:36Z","board_verified":true,"closed_at":null,"days_open":1,"trust":{"level":"ok","repost_count":null,"flags":[],"days_open":1},"description":"The role / impact\nThis senior engineering position owns a critical delivery stream on MyXero, the foundational platform that underpins every organisation and user record while managing hundreds of millions of daily requests. You will take ambiguous platform challenges from problem framing to durable architectural solutions, designing the specs, verification harnesses, and AI guardrails that enable software agents to handle implementation safely.\nYour work directly enables the modernisation of a massive system into decoupled domain services without disrupting dependent products. By engineering automated verification loops and robust testing harnesses, you will ensure high reliability, mentor team members, and shape how our engineering practices operate safely with intelligent tools.\nThe team / how they connect\nYou will join the MyXero Ghostbusters squad within our Identity and Platform group, collaborating with engineers and product partners primarily based across New Zealand. The team operates with a written-first, remote-first philosophy, using design records, paired kick-offs, and blameless reviews to ensure every voice is heard and no one works in isolation. While delivery is high-tempo, the group maintains a supportive, open environment where technical curiosity and shared learning are core to daily routines.\nInitially, you will focus on\nSetting up an intentional local development harness with automated validation checks to safely handle production changes.\n\nRefactoring legacy monolith endpoints and services built on .NET Framework, C#, and SQL Server towards modern APIs.\n\nDeveloping automated verification loops, test simulation harnesses, and tools that reduce operational toil and human checks.\n\nBuilding cloud agent tooling and collaborative workflows that support the evolution toward an automated development lifecycle.\n\nWhere and how you can work\nThis role is open to candidates based in New Zealand, offering a flexible remote-first setup with office access in Wellington or Auckland. Our working environment is structured around async communication and balanced collaboration.\nHere are some of the things we are looking for\nYou bring deep full-stack or backend engineering experience with typed languages, ideally with exposure to C# and .NET environments.\n\nHands-on exploration with AI harnesses, coding agents, or automated verification pipelines in a personal or professional setting.\n\nPractical familiarity with distributed systems architecture, API design, data modeling, and managing complex relational database migrations.\n\nProven capability in taking ambiguous technical problems from initial conception to production delivery.\n\nStrong written communication skills to articulate system trade-offs clearly through design records and technical documentation.\n\nA collaborative mindset with a drive to share learnings, uplift team capabilities, and contribute constructively to production support rotations.\n\nApply even if your experience isn't a perfect match! 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