Claude Code Guide: Setup and Your First Code Fix
Learn how to start with Claude Code, add useful CLAUDE.md instructions, make a focused change, review checks, and use official desktop and mobile access.
Research checked October 30, 2026 · SideHustleLab
This Claude Code guide takes you from choosing the official setup route to checking a useful first result. If you are still deciding whether the product fits, start with our Claude Code review.
Before you begin: use an account and project you are authorized to access, a small non-sensitive sample, and a clear stopping point. Installation instructions belong on the device or environment you choose; reading this guide does not install anything.
Official downloads and mobile access
Claude Code mobile access is inside the Claude app for iOS and Android; there is no separate Claude Code phone app. It connects to supported cloud or remote work rather than running a codebase on the phone.
Select the interface and installer for your device.
Claude Code access is inside the official Claude app.
Use the official Anthropic app.
Check cloud-session and Remote Control requirements.
How to get started with Claude Code
1. Use the official installation guide
Choose terminal, desktop, web, or an editor integration from Anthropic’s overview. For a terminal installation, follow the command for your operating system on the current quickstart page. Confirm that the account or provider route you plan to use supports Claude Code.
2. Open a small development project
Use a local repository or an authorized cloud project with a recovery point. Check for uncommitted work before starting. Identify what the issue touches and which services should not be accessed during the trial.
3. Launch and inspect before changing
After installation, run claude in the project directory and complete sign-in. Ask it to explain the structure and available checks first. If the project cannot run locally, resolve that limitation or select a task with a verifiable result before requesting a feature.
4. Give the project a concise CLAUDE.md
Document the important conventions, test commands, and boundaries in a CLAUDE.md file. Keep secrets out of it. State how to validate changes and which directories are generated or externally managed so the agent has useful context without a wall of stale instructions.
5. Describe the bug and acceptance checks
Supply a reproducible example, expected behavior, and constraints. The sample prompt below asks for one validation fix and one relevant regression check. Use a short plan for a task with uncertain scope before allowing a wide refactor.
6. Inspect the diff and verification
Ask which checks actually ran and open the changed files yourself. Check that the solution preserves valid behavior as well as rejecting the broken case. If a check is blocked by a missing dependency, report that as unresolved rather than treating it as a pass.
7. Use mobile access for follow-up
The Claude app’s Code tab can reach supported cloud or remote sessions; it does not run your local repository directly on the phone. Install the official Claude app below, use the same intended account, and follow the mobile guide for the session type you need.
A practical first task
Before the task, record one valid input and one invalid input with the expected outcomes. After the change, test both. A fix that rejects everything is not successful even if it blocks the original bad input. Review the relevant behavior manually as well as the reported checks.
Example prompt to adapt
Find the validation code for this sample form and explain why the supplied invalid input is accepted. Make the smallest fix that satisfies the stated rule, add a relevant regression check, and run it. List changed files and unresolved limitations. Do not change deployment settings or publish the result.
What a good result looks like
- The deliverable matches the requested scope and uses the supplied inputs.
- Claims or changes have evidence you can inspect, including source links or relevant checks.
- The agent explains anything it could not verify instead of presenting assumptions as completed work.
- No unrequested external action is treated as part of the task.
Common problems and what to check
The command is not recognized
Follow the quickstart’s installation and PATH troubleshooting for your shell. Open a new terminal after installation before assuming the package failed.
Claude keeps missing project conventions
Make the relevant instructions concise and specific in CLAUDE.md. Remove contradictions and verify that the session is in the intended project.
The phone shows no expected session
Check the account, Code tab, and whether you are using a cloud session or Remote Control. The phone is a client for a session running elsewhere.
Make the next run easier
Keep a short record of the input, output, correction time, and any usage charge. Repeat the same small task with one changed input before increasing the scope. If you cannot tell whether a result is correct, improve the acceptance checks before delegating a larger job.
Sources and editorial approach
This is a research-based editorial assessment of official product documentation, checked October 30, 2026. The suggested tasks and evaluation criteria are SideHustleLab examples, not claims of hands-on testing or guaranteed results. Product access, interfaces, and prices can change.