Minions: Stripe’s one-shot, end-to-end coding agents—Part 2

Summary

Stripe’s minions are an unattended agentic coding flow whose pull requests are human-reviewed but contain no human-written code; more than 1,300 merge weekly. The system runs agents in AWS EC2-based devboxes that are prewarmed to become usable within about 10 seconds, providing parallel, predictable, and isolated environments. Its custom harness uses code-defined blueprints that combine deterministic nodes, such as linting and pushing changes, with agent loops for tasks such as implementation and fixing CI failures. Minions receive automated feedback through local linting, one full CI iteration, and a possible second repair attempt, while devbox isolation and security controls limit destructive actions; Stripe presents the approach as an extension of long-running investments in human developer productivity.

Context

Unattended coding agents need parallel, predictable, and isolated environments, but running them on developer laptops makes it difficult to provide both the power of a developer shell and appropriate constraints. Agents also need automated feedback without depending entirely on expensive, slow CI iteration.

Approach / What changed

Stripe runs minions on prewarmed AWS EC2 devboxes and uses a custom harness based on code-defined blueprints. Blueprints interleave deterministic code nodes with agent loops, while local linting, CI feedback, devbox isolation, and internal security controls support unattended execution.

Takeaways

• Stripe’s prewarmed devbox pool includes repository checkouts, Bazel and type-checking caches, and running code-generation services, targeting readiness within 10 seconds.
• Blueprints combine deterministic operations with flexible agent nodes, allowing predictable subtasks such as linting and pushing changes to run without invoking an LLM.
• The standard minion flow performs local lint iteration, one full CI run, and one possible repair attempt before returning the branch to a human for scrutiny.

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