A Clear Diff Explanation Makes Agent Reviews Safer

A coding agent can change several parts of a project before a newcomer has finished reading the first edit. That speed is useful, but it creates a review problem: working software can still contain an unintended behavior change. Before merging, ask the agent to explain its diff, the record of lines added and removed. Treat that explanation as a map for your inspection, not permission to skip it.

A useful explanation starts with intended behavior

Begin by asking the agent to restate the task in plain English. It should describe the original problem, the expected result, and the boundaries of the work. This gives you a simple reference point: each meaningful edit should support that result or have a clear, separate justification.

Then ask for a behavior-focused explanation rather than a tour of edited lines. Renaming a variable and changing access permissions are not equally important. A useful account explains the effect on users, callers, stored information, and failure handling. It also identifies behavior intended to remain unchanged.

You can make this request directly: Explain the problem this change solves, the behavior it changes, and the behavior it must preserve. Separate necessary edits from cleanup. This is a review instruction, not a request for the agent's private reasoning.

Every important claim needs something you can inspect

An explanation becomes useful when it points to evidence. Ask the agent to connect each major claim to the relevant part of the diff. You should be able to locate the changed condition, follow the updated data flow, or inspect the test that supports the claim.

Pay particular attention to small edits with large consequences. A different default value, a removed permission check, or an altered retry rule can matter more than a large formatting change. Ask the agent to flag changes involving authentication, deletion, payments, external requests, and sensitive information.

Keep the scope explicit, too. Confirm that the explanation covers the actual changes awaiting review, including new files. If the agent makes another edit after explaining the diff, request an updated account. An accurate explanation of an earlier version does not describe the version you are merging.

Test results deserve precise labels and limits

Ask the agent to separate tests it actually ran from tests it merely recommends. For executed tests, request the outcome and any relevant limits. A passing focused test does not establish that the whole application works, and an unavailable test environment is not a passing result.

Request one normal example and one failure example in everyday language. For a form change, these might cover valid input and missing required information. Compare those examples with the tests and implementation. If the agent claims an edge case is handled but cannot identify supporting evidence, keep that claim unresolved.

Model access does not replace independent review

The same review habit applies across tools. BestRelay, this article's publisher, is a quality-first API relay that forwards each request to the official model named in it without substitution. It supports Claude, GPT, Gemini, DeepSeek, Kimi, GLM, Qwen, Grok, and more, and works with Claude Code, Codex, Gemini CLI, and any OpenAI SDK.

Billing is pay-as-you-go using provider-reported token counts, with cache reads and writes priced separately. Members also earn a referral commission when invited users top up. These are service details, not evidence that an explanation is correct. Create a BestRelay account if that setup suits your workflow.

A merge decision should name remaining uncertainty

Finish by asking for the main risks, assumptions, and areas needing human review. Useful answers acknowledge missing context instead of presenting confidence as proof. Read the important edits yourself, check the reported test evidence, and involve a knowledgeable reviewer when the consequences exceed your experience.

You do not need to understand every line immediately. You do need a clear account of the intended change, evidence supporting it, and an honest description of unresolved risk. If those pieces are missing, pause the merge and ask for a smaller change or a clearer explanation.