Claude CLI

Use Claude CLI when you want strong reasoning and structured output from Anthropic models.

Requirements

• claude CLI installed.

• Authentication completed (ANTHROPIC_API_KEY or claude login).

Setup

1. Install CLI:

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

1. Authenticate:

export ANTHROPIC_API_KEY="sk-ant-..."
# or
claude login

1. Verify locally:

claude "hello"

1. Configure in AI Backend settings tab.

Configuration

Setting	Value
Preferred Backend	Claude CLI
Claude CLI Command	claude or full path

Model example:

claude --model sonnet

Notes

Large Prompt Fallback

For prompts above 32_000 characters (the internal LARGE_PROMPT_THRESHOLD), the extension avoids passing the full text on the command line. Instead it:

1. Writes the combined prompt to a temp file named burp_uv_prompt_*.txt with POSIX permissions 0600 where supported.

2. Invokes Claude with an instruction such as "Please process the instructions and data provided in the following file: <path>", passing the path as an argument.

3. Deletes the temp file in a finally block after the response is consumed.

This avoids OS-level argv/stdin length limits on long contexts while keeping the prompt on-host.

Session Resume

Claude CLI sessions are kept sticky across turns:

• The first turn is launched with --session-id <uuid>.

• Subsequent turns on the same chat session use --resume <uuid> so conversation history is reconstructed inside Claude rather than replayed by the extension. The session ID is held in a thread-safe AtomicReference with CAS updates.

If the process is killed or Clear Chat is used, the session ID is released and a new --session-id is minted on the next turn.

Windows

npm-installed CLI shims are resolved automatically on Windows. The extension detects .cmd siblings and uses them instead of shell script shims that Java cannot execute directly.

Windows + WSL bridge

If Burp runs on Windows and Claude CLI is installed inside WSL, the simplest setup is to point Claude CLI Command at a one-liner that invokes WSL with an interactive shell so PATH and auth env vars from ~/.bashrc / ~/.profile are loaded:

wsl -d Debian bash -ic "/home/<username>/.local/bin/claude"

Notes:

• Replace Debian with the name of your distro (wsl -l -v lists installed ones) and <username> with your WSL user.

• bash -ic runs an interactive shell that sources rc files, so ANTHROPIC_API_KEY (or whatever claude login wrote) is picked up; -c then executes the binary.

• Use the absolute path to the claude binary inside WSL (which claude from WSL prints it). Relying on bare claude can fail if the rc files don't put ~/.local/bin on PATH for non-login shells.

• No .cmd wrapper file is required — the extension passes its CLI args through the same way it does for native commands.

If you prefer a wrapper script instead of a single command (e.g. to filter banner output, switch distros, or share the config across machines), the .cmd pattern documented for Codex CLI works the same way for Claude.

Troubleshooting

• command not found: use full binary path.

• Windows: npm shim paths are resolved automatically. If auto-resolution fails, use the full .cmd path: C:\\Users\\<you>\\AppData\\Roaming\\npm\\claude.cmd.

• Auth issues: re-run claude login or verify ANTHROPIC_API_KEY.

• Empty output: check Burp extension output/errors tabs and model flag validity.

Related Pages

• Backends Overview

• Troubleshooting