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Agent Runtime & Systems - Member of Technical Staff

Callosum· General Capabilities
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LondonFull-timePosted 2mo ago

About the role

Role focused on the runtime and programming model for long-running agent systems, including durable execution, checkpointing, distributed scheduling, secure tool execution, and end-to-end observability across a distributed, fault-tolerant agent framework.

Responsibilities

  • Design and build stateful, asynchronous agent runtimes across distributed environments
  • Define event histories, checkpoint and resume semantics, deterministic reconstruction, retries, cancellation, timeouts, and recovery from partial failure
  • Build traces and replay, time-travel debugging, and hierarchical tracing across model calls, tools, handoffs, state changes, and runtime decisions
  • Develop clear Python APIs, libraries, and DSLs with stable extension points for tools, backends, and new execution models
  • Design scheduling, placement, backpressure, resource accounting, sandboxing, permissions, and isolation for secure tool execution at scale
  • Develop tooling for trajectory collection and visualisation, performance profiling, experiment comparison, failure attribution, and regression detection across models, prompts, tools, and runtime versions

Qualifications

  • Strong distributed systems background with hands-on experience in durable workflows, actor systems, schedulers, workflow engines, distributed databases, or stream processors
  • Experience designing a library, framework, runtime, or DSL that other engineers or researchers adopted
  • Deep Python expertise plus proficiency in a systems language such as Rust, C++, or Go - and the instinct to move between abstraction layers when it matters
  • Hands-on debugging skills across APIs, runtimes, and distributed infrastructure - with a practical understanding of nondeterminism, side effects, and reproducibility

Skills

Required:Distributed systemsPythonRust/C++/Go

Benefits

  • Competitive Salary, determined by skills and experience
  • Equity & Ownership
  • Private healthcare
  • Visa sponsorship and relocation benefits to hire the best in the world
  • We work in person at our London office. Tools and setup provided; accommodations available on request
Last updated Oct 14, 2026. Interested? Apply on the company site.

About Callosum

The Intelligent Systems Company.

Callosum - Co-evolving chips & intelligence

AISystems companychipscomputedevelopmentheadline-ai-europe-100-2026heterogeneousinfrastructure
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