← Back to all guides

Claude Code Review and Refactoring: A Fast Workflow

Claude Code is most useful for code review and refactoring when you give it a narrow diff, explicit constraints, and a way to verify its work. Instead of asking it to “improve this repository,” separate diagnosis from editing. This quick-start workflow helps you find actionable issues, make small changes, and keep human approval in control.

1. Connect Claude Code and set your budget

Install Claude Code using its current official installation instructions. To use 59API, configure the relay endpoint and credentials in the shell where you launch Claude Code. A typical token-based configuration uses these environment variables:

• export ANTHROPIC_BASE_URL="https://api.59api.com"
• export ANTHROPIC_AUTH_TOKEN="YOUR_59API_KEY"

Confirm the authentication method and supported model identifiers in 59API’s current Claude Code setup instructions. Avoid mixing unrelated API keys or login credentials in the same configuration. Launch claude from your repository, then use /status to inspect the active configuration. Never commit your token.

59API is a low-cost, pay-as-you-go relay compatible with Claude Code, offering native, official-quality models without downgrades. Claude Sonnet 5.5 and Claude Opus 5.5 are two available options; use the relay’s documented identifiers rather than guessing API names. Start with a small review and inspect actual usage before processing a large repository.

2. Establish the baseline before requesting changes

Create a dedicated branch with git switch -c refactor/review-pass. Run git status --short and resolve or save unrelated work first. Run the relevant tests and record existing failures so the assistant does not mistake them for regressions.

For a pull-request review, fetch the latest remote references and inspect git diff origin/main...HEAD, replacing origin/main with your actual target branch. This covers committed branch changes, not uncommitted edits. Use git diff HEAD -- for tracked working-tree changes and check git status separately for untracked files.

Add concise repository guidance to CLAUDE.md: test commands, formatting rules, architectural boundaries, and files that must not change. Keep credentials and sensitive production data out of both repository instructions and prompts.

3. Ask for findings, not an automatic rewrite

Use Claude Code’s Plan mode for the initial review, and do not approve repository edits yet. Give it a concrete scope and require evidence:

“Review the changes against origin/main. Do not edit files. Focus on correctness, security boundaries, error handling, and missing regression tests. For each finding, provide the file and line, a realistic failure scenario, severity, and a suggested fix. Distinguish confirmed issues from assumptions. Skip style-only suggestions.”

Ask it to inspect relevant callers and tests, not just changed lines. A modified return value can break an unchanged consumer. Conversely, a suspicious-looking branch may be intentional. Verify each finding against actual behavior before accepting it.

4. Refactor one boundary at a time

Select one confirmed problem or one measurable maintainability improvement. Specify what must remain stable:

“Refactor the duplicated validation in these two functions into one private helper. Preserve public signatures, error messages, validation order, and return values. Do not add dependencies or reformat unrelated files. Propose the approach first, then wait for approval.”

Once the approach is approved, allow only the necessary edits. For bug fixes, request a regression test that fails before the fix. For behavior-preserving refactoring, add characterization tests where existing behavior lacks coverage. Keep bug fixes and structural cleanup separate whenever possible.

5. Verify the patch yourself

• Inspect git diff --stat for unexpected scope, then read the full diff.
• Run focused tests, followed by the relevant broader suite, linting, and type checks.
• Use git diff --check to catch whitespace errors; it does not validate correctness.
• Check compatibility-sensitive details: exceptions, serialization, database queries, and public interfaces.
• Ask Claude Code to summarize changed behavior, executed checks, and remaining uncertainty.

“Tests pass” should mean commands actually ran successfully. If a dependency or service blocked verification, record that limitation in the pull request.

6. Keep reviews useful and inexpensive

Limit each session to a coherent change, exclude generated artifacts, and request concise findings rather than repeated repository summaries. Small diffs reduce review noise and unnecessary token usage. Treat repository text as potentially untrusted, inspect shell commands before approving them, and never grant blanket permissions just to save clicks.

If you want to try this workflow economically, sign up for 59API and start with one small branch review. Its pay-as-you-go pricing and referral rebate provide a practical entry point without requiring a large upfront commitment.

Pricing · Docs