Safe Installation and Usage Guide for Command-Line AI Coding Assistants

1. Understand What These Tools Can Do

Command-line AI coding assistants run in the terminal. They can read files in the current project, analyze code structure based on natural-language instructions, and help write, modify, test, refactor, and document code.

Their main difference from standard code completion tools and IDE extensions is their working scope. Code completion tools typically focus on a few lines near the cursor, while command-line assistants can work across the entire project directory. You can ask one to locate the implementation of a feature, add an API endpoint, fix failing tests, or explain complex logic.

Comparison	Code Completion	IDE Extension	Command-Line AI Coding Assistant
Scope	Near the cursor	The currently edited file	The entire project directory
Typical tasks	Complete a line or code block	Generate a function or explain selected code	Modify multiple files, run tests, and troubleshoot issues
Main risks	Incorrect generated snippets	Unintended changes to the current file	Bulk changes, command execution, and access to sensitive files
Required permissions	Very limited	Editor permissions	File read/write access, command execution, and potentially network access

These tools do not replace developers. Their output may still contain logic errors, missed edge cases, incompatible dependencies, or security issues. A reasonable workflow is to describe the task, review the changes, run validation, and continue refining the result based on the outcome.

2. Check the Local Environment Before Installation

Before installing an assistant, confirm that the project itself runs correctly. If the project cannot build or pass its tests, the assistant may incorrectly interpret an environment problem as a code problem.

For a Node.js project, run the following commands to check the environment:

node -v
npm -v
git --version

All three commands should return version numbers. Claude Code requires Node.js 18 or later. For other tools, check the minimum required version in their official documentation.

Next, install the project dependencies and run the tests from the project root:

npm install
npm test

Record the output produced under normal conditions. If the test results change later, you can quickly determine whether the issue was caused by a code modification.

3. Install and Sign In

For Claude Code, install the package globally with npm:

npm install -g @anthropic-ai/claude-code
claude --version

The terminal should display the installed version. If the command is not found, check whether npm’s global installation directory has been added to the PATH environment variable.

For the first sign-in, run claude from the project directory and follow the authorization prompts. If your environment requires a key to be provided through an environment variable, use the following format:

export ANTHROPIC_API_KEY="<your-api-key>"

Never write a real API key into project files, scripts, or commit history. A safer approach is to retrieve it from a password manager or the system keychain and inject it into the environment of the current session.

4. Configure Permissions and Grant Only What Is Necessary

After installation, define what the assistant is allowed to do. Consider which directories it can read, which files it can modify, whether it can run build and test commands, whether it can access the network, whether it can read environment variables, and whether it can delete or bulk-rename files.

Project-level permissions can be defined in .claude/settings.json. The following example allows only test and build commands while denying access to environment files and secret directories:

{
  "permissions": {
    "allow": [
      "Read",
      "Bash(npm test)",
      "Bash(npm run build)"
    ],
    "deny": [
      "Read(./.env)",
      "Read(./secrets/**)",
      "Bash(rm:*)"
    ]
  }
}

Edit is not included in the allow list, so the assistant will request confirmation before modifying files. Permission syntax may change between versions; refer to the official documentation for the version you are using.

For projects containing business source code, customer data, or internal configuration, consider testing the tool in a test project or a sanitized copy first. Only grant broader permissions to the production repository after confirming that its behavior meets your expectations.

5. Steps for the First Project Session

First, enter the project root and check the repository status:

cd /path/to/your-project
git status

The expected result is a clean working tree or only changes whose origin you clearly understand. If unrelated changes are present, handle them before asking the assistant to begin work.

Next, start the assistant and generate a project instruction file:

claude

After entering the interactive interface, run /init. The assistant will analyze the project and generate a project instruction file. Review the generated content line by line. Remove incorrect descriptions and add conventions that cannot be inferred directly from the source code, such as branch policies, test commands, and directories that must not be modified.

Then ask the assistant to understand the project before changing any code. For example:

First read the project instruction file and the main directory structure. Summarize how the project runs, its core modules, the test entry points, and any current technical risks. Do not modify any files yet.

The expected result is a summary of directory responsibilities, the technology stack, and the test commands. Compare each item with the actual project. If the assistant has misunderstood anything, correct the context before starting the actual task.

6. Write Actionable Task Instructions

Good instructions do not depend on length. They depend on whether the necessary information is complete. A practical structure is:

Background: Describe the module, its current behavior, and the observed problem.
Goal: Clearly define the result you want to implement or fix.
Scope: Specify the directories and files that may be modified.
Constraints: Specify interfaces and compatibility requirements that must not change.