New opportunity

Senior Full-Stack AI Engineer

CellStrat · Remote

About this role

CellStrat is seeking a Senior Full-Stack AI Engineer for a fully remote position. The role splits focus between building end-to-end AI engineering solutions for a US client project (80%) and contributing to CellAssist, an internal healthcare voice AI platform (20%). Work requires night IST availability to attend US client meetings and occasional weekend support.

Responsibilities

  • Own features end to end across design, build, code review, testing, release, and monitoring
  • Architect and build backend services using Python and FastAPI, handling SaaS multi-tenancy, service boundaries, async workflows, and infrastructure
  • Design and construct agentic and multi-agent AI systems from first principles, including agent orchestration, tool/MCP server integrations, memory, state handling, evals, and guardrails
  • Implement production LLM engineering techniques such as prompt caching, context management, and memory strategies to manage latency, cost, and reliability
  • Conduct rigorous code reviews across the engineering team, covering both human-written and AI-generated code
  • Build and maintain frontend features using React, Next.js, or TypeScript when needed
  • Participate directly in US client discussions during India night hours to analyze business domains
  • Leverage AI-assisted development tools like Cursor and Claude Code to accelerate delivery

Required qualifications

  • 3 to 7 years of relevant experience
  • Python as the primary backend language with strong core fundamentals (OOP, decorators, generators, async) and FastAPI experience
  • Proven track record of shipping at least one production-grade agentic or multi-agent AI system with real end users
  • Demonstrated software architecture ownership, including HLD, LLD, service boundaries, and multi-tenant architectures
  • Strong technical reasoning skills to justify architectural and tooling decisions
  • Hands-on coding proficiency alongside AI development tooling
  • Working knowledge of React, Next.js, or TypeScript sufficient for debugging and feature implementation
  • Availability for night IST client calls (1–1.5 hours) and occasional weekend production support

Preferred qualifications

  • Experience building pure Python agents from first principles without LangChain or LlamaIndex
  • Active GitHub profile with recent Python and FastAPI projects
  • Cloud engineering experience on Google Cloud Platform (GCS, IAM, Pub/Sub, Cloud Tasks) beyond Cloud Run
  • Familiarity with LLMOps, evaluation infrastructure, prompt versioning, and AI observability
  • Prior experience leading design reviews, mentoring engineers, or working with US clients

Benefits

  • ₹25–35 LPA fixed CTC based on experience, plus ESOP opportunities
  • Fully remote working arrangement with flexible hours
  • Direct exposure to production AI products, modern cloud infrastructure, and advancing agent ecosystems

For full details about this role, click “Apply on company site” to view the employer’s original posting.

Skills for this role

PythonFastAPIAgentic AIMulti-agent AI systemsReactNext.jsTypeScriptCursorClaude CodeLLM EngineeringPrompt EngineeringMCP ServersGCPLLMOpsSystem Architecture

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Get interview-ready for this role

A focused preparation guide, built around this job’s responsibilities and requirements.

✦ AI-generated guide
Preparation suggestions, not the employer’s actual interview questions. Always check the original posting for current requirements.
01

Understand the role

What matters most

  • First-Principles Agentic and Multi-Agent Architecture

    The role prioritizes designing and implementing agentic workflows from first principles, specifically focusing on agent orchestration, MCP server and tool integrations, state handling, memory management, evals, and guardrails without over-relying on high-level wrapper frameworks like LangChain.

  • Robust Backend and SaaS Engineering in Python and FastAPI

    Core engineering centers on writing idiomatic Python and FastAPI backends, owning system architecture from HLD to LLD, and addressing multi-tenancy, service boundaries, async workflows, and production data models for scalable enterprise deployments.

  • Production LLM Optimization and Cost-Latency Governance

    Engineers are expected to handle real-world LLM operational constraints, including prompt engineering, context window management, prompt caching, memory strategies, and latency/reliability trade-offs in customer-facing production systems.

  • End-to-End Feature Ownership and Direct Client Engagement

    The position requires taking features from initial concept through design, code review, testing, deployment, and monitoring, combined with direct participation in night IST discussions with US clients to decipher domain requirements without pre-written specs.

Likely challenges to think through

  • Balancing First-Principles Agent Implementations Against Framework Abstractions

    Preparation Hypothesis: The team emphasizes building agents without wrapper libraries to ensure granular control over memory, latency, and tool execution. The trade-off is higher boilerplate and custom state management versus faster prototyping with out-of-the-box abstractions. Prepare by practicing building custom agent loops, state machines, and Model Context Protocol (MCP) tool integrations purely with native Python and async primitives.

  • Maintaining Code Rigor Under Accelerated AI-Assisted Workflows

    Preparation Hypothesis: Using tools like Cursor or Claude Code speeds up code output but increases the risk of subtle bugs, security flaws, or unmaintainable logic in human and AI-authored PRs. Prepare concrete code review criteria covering edge cases, async concurrency issues, and defensive guardrails tailored to AI-generated code.

  • Handling Non-Deterministic LLM Behavior and Production Latency

    Preparation Hypothesis: Deploying multi-agent systems to real users introduces compounding latency and reliability vulnerabilities from flaky tool calls or unpredictable model responses. Prepare by outlining robust evaluation frameworks, fallback heuristics, context window pruning, and prompt caching patterns used to enforce strict SLAs.

  • Navigating Asynchronous US Client Communication and Unspecified Requirements

    Preparation Hypothesis: Shifting between US night calls (80% client work) and independent daytime execution demands rapid domain translation without hand-held specifications. Prepare examples demonstrating how to clarify ambiguous business objectives, document architectural trade-offs, and maintain sustainable routines across time zones.

03

Practice your answers

Technical practice

How would you architect a pure Python multi-agent system from first principles without high-level agent frameworks?

What to coverSuggested practice: Explain how you would implement agent loops, state machines, and task orchestration directly in native Python using async primitives. Address message passing, dynamic tool dispatch, and how avoiding abstractions like LangChain or LlamaIndex influences debugging and latency control.

How do you handle multi-tenant isolation and async workflows in a Python and FastAPI backend service?

What to coverSuggested practice: Discuss architectural patterns for SaaS tenant segregation at the database and application levels, such as tenant keys, schema routing, or connection scoping. Highlight how you leverage FastAPI dependencies, background tasks, or distributed workers like Celery or Pub/Sub to manage async execution safely across tenants.

What strategies do you use to integrate and secure external tools and MCP servers within an agentic workflow?

What to coverSuggested practice: Focus on schema definition, tool-calling validation, and error recovery when invoking external tools or Model Context Protocol (MCP) servers. Describe the security guardrails, timeout handling, and permissions required to prevent prompt injection or unintended system state mutations.

How do you optimize LLM performance, latency, and operational cost using prompt caching and context management?

What to coverSuggested practice: Detail how you structure conversational context, system prompts, and tool definitions to maximize provider-level prompt caching hit rates. Discuss truncation strategies, dynamic context window pruning, and trade-offs between full conversational fidelity and token budget constraints.

How do you design an evaluation harness and observability pipeline for production agentic systems?

What to coverSuggested practice: Explain how you implement automated evals, synthetic test benches, and prompt versioning to detect regression in non-deterministic agent outputs. Address tracing tool calls, latency tracking per step, and monitoring failure modes using observability tooling in production.

How do you approach code reviews when evaluating AI-generated code alongside human-written pull requests?

What to coverSuggested practice: Outline the specific verification steps you apply to catch subtle logic bugs, phantom dependencies, edge cases, and architectural anti-patterns common in AI-assisted development. Discuss how you maintain standards for typing, test coverage, and long-term maintainability without throttling delivery velocity.

How do you diagnose and resolve asynchronous state and concurrency issues in FastAPI backend services?

What to coverSuggested practice: Describe how you troubleshoot blocking I/O calls accidentally placed within async event loops, race conditions in shared state, and resource starvation. Address how you use Python profiling tools, async context managers, and FastAPI middleware to trace and remediate concurrency bottlenecks.

How do you implement UI feature changes and debug frontend issues in a Next.js and TypeScript application?

What to coverSuggested practice: Explain your workflow for isolating bugs across server-side rendering (SSR) and client-side components within Next.js. Address how you type API responses, manage shared state, and ensure frontend integration aligns with the underlying FastAPI backend endpoints.

How would you architect an event-driven system on Google Cloud Platform using Pub/Sub and Cloud Tasks for agentic tasks?

What to coverSuggested practice: Suggestion: Address how you decouple long-running LLM generation steps from user-facing APIs using GCP Pub/Sub for event broadcasting and Cloud Tasks for rate-limited, retriable job dispatch. Detail IAM role separation, dead-letter queue handling, and storage patterns with GCS.

Behavioural practice

Describe a situation where you had to uncover ambiguous business requirements directly during a client discussion.

What to coverSuggested practice: Frame a real example using situation, action, and result showing how you engaged with stakeholders to clarify vague domain needs rather than waiting for an explicit spec. Highlight your approach to translating client problems into precise technical deliverables.

Tell me about a time you made and defended an architectural trade-off that went against popular tooling trends.

What to coverSuggested practice: Share a situation where you had to justify a specific technical choice over conventional or heavily hyped alternatives (such as avoiding a complex framework or selecting a specific database pattern). Focus on your rationale, stakeholder communication, and the measurable production impact.

Describe a scenario where you had to triage and resolve an urgent production incident outside standard business hours.

What to coverSuggested practice: Provide an example illustrating your response to a high-severity production failure during off-hours or weekend on-call. Detail the immediate containment actions, systematic root-cause diagnosis, cross-timezone communication, and subsequent preventative hardening.

Tell me about a time you mentored an engineer or aligned a team through rigorous code review standards.

What to coverSuggested practice: Detail a situation where you identified architectural flaws or code quality issues in a colleague's work, including AI-generated contributions. Explain the actions you took to give constructive, actionable feedback and how it improved overall engineering rigor.

02

Sharpen your knowledge

Topics to prepare

  • First-Principles Agentic Orchestration and State Management

    Relevance: Required duty to design and build agentic and multi-agent AI systems from first principles, specifically without defaulting to high-level framework wrappers like LangChain or LlamaIndex. Exercise: Diagram and write out the state transition schema for a multi-agent system handling user requests, detailing message history maintenance, tool invocation loops, context isolation between agents, and deterministic guardrail checks.

  • Production LLM Optimization and Latency/Cost Management

    Relevance: Explicit requirement covering LLM-layer engineering, specifically prompt engineering, context management, memory strategies, and prompt caching to govern latency, cost, and reliability. Exercise: Compare semantic caching vs exact-match prompt prefix caching, and write a technical justification detailing when each approach minimizes token costs and response latency for a multi-turn conversational agent.

  • SaaS Multi-Tenancy and Backend Architecture Principles

    Relevance: Core requirement for software architecture ownership, designing systems from scratch across HLD/LLD, multi-tenant patterns, service boundaries, and asynchronous workflows. Exercise: Outline an architectural design document for a multi-tenant API serving isolated enterprise clients, detailing tenant data isolation, shared vs dedicated vector stores, and rate-limiting strategies for external LLM endpoints.

  • Trade-Off Reasoning in AI and Backend Systems

    Relevance: Mandatory qualification requiring engineers to justify technology choices over alternatives (e.g., why RAG vs no RAG, vector DB selection, or deployment models) without framework stacking. Exercise: Draft a structured trade-off evaluation comparing a pure tool-calling agent against an embedding-based retrieval pipeline (RAG) for answering structured domain queries, articulating latency, maintenance, and failure modes.

  • LLMOps, Evals, and AI Observability

    Relevance: Listed under preferred qualifications for evals infrastructure, prompt versioning, and production observability. Exercise (Inferred preparation suggestion): Formulate an offline and online evaluation rubric for assessing voice or text agents, defining concrete metrics for hallucination detection, tool-call accuracy, and latency tracing.

Skills to revise

  • Rapid Python and FastAPI Defect Resolution and Async Programming

    Relevance: Directly assessed in Round 1 proctored live coding (fixing missing Python/FastAPI code in 20 minutes) and tests mandatory core fundamentals (OOP, decorators, generators, async). Exercise: Practice downloading an incomplete FastAPI repository and under a 20-minute timer implement missing async endpoints, Pydantic request models, custom decorators, and async database session handling.

  • Vanilla Python Agent Implementation and MCP Tool Integration

    Relevance: Directly matches the take-home assignment and preferred skill of building agentic systems without LangChain or LlamaIndex, integrating Model Context Protocol (MCP) servers and tools. Exercise: Implement an autonomous agent loop from scratch using standard Python async functions and an LLM client library that reads an MCP tool schema, dispatches local tool functions, and handles tool execution errors gracefully.

  • AI-Assisted Accelerated Engineering (Cursor / Claude Code)

    Relevance: Source specifies using AI-assisted tooling (Cursor, Claude Code) to ship fast while maintaining rigorous code quality and architectural integrity. Exercise: Build a small end-to-end microservice using Cursor or Claude Code, practicing prompt workflows to scaffold FastAPI routes, then perform a manual security and correctness audit of the generated code.

  • Full-Stack Integration with React, Next.js, and TypeScript

    Relevance: Stated requirement to contribute to frontend work and debug UI issues across React, Next.js, or TypeScript without needing full ownership. Exercise: Build a minimal Next.js client with TypeScript that connects to a FastAPI streaming response endpoint via Server-Sent Events (SSE) and displays real-time agent output with loading and error boundaries.

04

Your preparation checklist

  • Practice rapid Python and FastAPI live debugging under time constraints

    Prepare for the 20-minute proctored coding test by completing timed exercises where you unpack a boilerplate FastAPI codebase, fix missing endpoints or broken dependency injections, and handle core async routines, decorators, and generators without looking up basic syntax.

  • Build a production-grade agentic walkthrough based on first principles

    Draft a structured technical walkthrough of a previously shipped multi-agent or agentic system, detailing its orchestration, memory handling, tool or MCP server integrations, and guardrails implemented in pure Python without reliance on frameworks like LangChain or LlamaIndex.

  • Document architectural trade-offs for SaaS multi-tenancy and async pipelines

    Create a clear comparison sheet showing high-level and low-level design decisions you have made, specifically covering tenant isolation, service boundaries, async message workflows (e.g., Pub/Sub or Cloud Tasks), and how trade-offs like RAG versus direct context injection were evaluated.

  • Prepare concrete evidence of production LLM engineering and optimization

    Compile concrete explanations showing how you implemented prompt caching, dynamic context management, and memory strategies in past projects to manage latency, operational token costs, and response reliability under real production workloads.

  • Review React, Next.js, and TypeScript frontend integration patterns

    Spend focused practice reviewing Next.js and React codebases to ensure you can quickly navigate component hierarchies, implement UI changes, and debug client-side API integrations connecting to Python backend services.

  • Formulate practical questions about client project scope and the CellAssist platform

    Draft specific questions for the team covering how time is allocated between the 80% US client project and the 20% CellAssist healthcare voice agent platform, operational expectations for night IST calls, and the current evaluation harness used in their AI pipelines.

AI-generated from the job information · Prepared Nov 4, 2026 (UTC)Useful preparation, not a guarantee of eligibility or an offer.

Availability last checked: 4 Nov 2026. Status can change after a check; confirm on the employer’s website. Report an issue · Our checking policy

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