Refactor Shift Note: Keep the Agent Ready to Resume

A coding agent can rename methods, move modules, and update callers quickly. During a long refactor, though, typing speed is rarely the main problem. The harder job is keeping the agent clear about the goal, the changes already made, and the evidence that the code still works.

Treat the session like a shift at an operations desk: keep a short log, make bounded changes, and leave the work ready for someone else to resume. That someone might be you tomorrow, or the same agent in a fresh conversation.

Write the refactor boundary before touching files

A refactor changes the structure of code without intentionally changing its behavior. Give the agent that boundary explicitly. “Clean up the billing package” leaves too much room for interpretation. “Move invoice formatting into a separate module while preserving public function signatures and output” gives it something concrete to finish.

Ask the agent to inspect the relevant files and propose a plan before editing. The plan should identify the affected callers, the tests that cover them, and anything that must remain unchanged.

• State which behavior and public interfaces must stay the same.
• Name the directories the agent may edit and any files it must leave alone.
• Define a stopping point, such as completing one extraction and passing its focused tests.

Keep a handoff note outside the conversation

Long conversations can become harder to navigate, and an agent may not retain every earlier detail. Put the essential state in a small repository note rather than relying on chat history alone. Avoid storing credentials, customer data, or other sensitive material in it.

The note should capture the objective, current checkpoint, decisions made, commands run, and next action. Record unresolved questions too. “The formatter moved, but two callers still import the old path” is more useful than “nearly done.”

Update this note after each meaningful checkpoint. Before starting a fresh session, ask the agent to read it and verify the working tree. A handoff note is a guide to inspect the code, not proof that everything in it is still true.

Make each edit small enough to verify

Avoid combining a module move, a dependency upgrade, and a broad naming cleanup in one step. When several things change together, failures become harder to explain.

Instead, have the agent complete one coherent slice. Inspect the diff, run the relevant checks, and commit the reviewed change before expanding the scope. Keep unrelated local work separate so the agent does not accidentally overwrite or include it.

If the same failure survives repeated attempts, stop the edit loop. Ask for a summary of the failure, the attempted fixes, and the smallest experiment that could distinguish between likely causes. More edits are not always more progress.

Use tests as evidence, not a completion ritual

Run relevant tests before editing to establish a baseline. Otherwise, an existing failure may be mistaken for a regression. After each slice, run focused tests first, then broader checks at suitable milestones.

Require the agent to report the commands it actually ran and their results. If a check could not run because a service or dependency was missing, that limitation belongs in the handoff. “Not verified” is different from “passed.” Review the diff yourself, especially around error handling, configuration, and public interfaces.

Keep model access separate from project memory

If you need access to multiple model families, Relay365 is a pay-as-you-go relay desk worth considering. It works with Claude Code, Codex, Gemini CLI, and OpenAI SDK clients. Its API base is https://api.api365relay.com; OpenAI clients add /v1.

Model access does not automatically carry project memory between tools or sessions. When changing models, reuse the handoff note and verification routine. Keep credentials outside the repository, and check usage as the session progresses. Create a Relay365 account if that access setup fits your workflow.

Close the shift with a resumable repository

End with reviewed changes, recorded test results, and one clear next step. A productive long refactor is not an uninterrupted conversation. It is a sequence of understandable changes that remain safe to inspect, pause, and resume.