Module 1 · Harnesses · Lesson 3

Agents as files with eve

How eve turns a directory of files into a durable agent service, what runs in the app runtime versus the sandbox, and how sessions checkpoint and resume after a crash.

70 min 1 video 3 exercises 7-question quiz Answers

Setup for the exercises:Install Claude Code Durable agents with eve Get an OpenRouter key Local models with Ollama OpenRouter or a local model?

By the end of this lesson you can

Place each part of an agent (rules, procedures, typed actions, working files, specialists, shared code) in the correct eve file or folder, and justify the choice
Write an eve tool with defineTool and a Zod input schema, and explain what runs in the app runtime and what runs in the sandbox
Trace a session through turns and steps, and predict what re-runs after a crash mid-turn
Configure the model for local development (OpenRouter or a local model) and explain what must change before deployment
Compute when compaction starts for a given context window, threshold and fixed prompt size

In the last lesson the agent was a function call: query() started Claude Code, the loop ran, and when your process died the in-flight work died with it. A conveyancing matter doesn't fit that shape. The buyer's solicitor raises enquiries on Monday, the seller's solicitor replies on Thursday, a search result arrives the following week, and the solicitor approves the report on title after that. eve is built for agents that live that long. This lesson shows how an eve agent is assembled from files, where each piece runs, and what "durable" actually guarantees.

eve is in preview. Its own docs say the framework, APIs and behaviour may change before general availability, so pin the version in package.json and read the changelog before upgrading. The snippets in this lesson were written against eve 1.0.0-rc.1; if your version differs, check them against the docs in node_modules/eve/docs/.

Agents as files with eve

How eve turns a directory of files into a durable agent service, what runs in the app runtime versus the sandbox, and how sessions checkpoint and resume after a crash.

Agents as files with eve

Agents as files with eve

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