Deterministic browser auth extraction for agent workflows. Use when you need to stop a running Brave/Chrome/Edge session, relaunch with CDP, extract cookie/localStorage/sessionStorage auth values, and restore normal browser state.
Scanned 9/20/2026
Install to Claude Code
npx -y skills add lev-os/agents --skill auth-sniffer --agent claude-codeInstalls into .claude/skills of the current project.
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---
name: auth-sniffer
description: Deterministic browser auth extraction for agent workflows. Use when you need to stop a running Brave/Chrome/Edge session, relaunch with CDP, extract cookie/localStorage/sessionStorage auth values, and restore normal browser state.
argument-hint: "--service <name> --robot [--browser brave] [--cookie <csv>] [--localStorageKeys=<csv>] [--sessionStorageKeys=<csv>] [--json]"
allowed-tools: Bash(auth-sniff:*)
skill_type: workflow
category: browser-auth
---
# Auth Sniffer Skill
Source of truth:
- FlowMind: `plugins/auth-sniffer/skills/auth-sniffer.flow.yaml`
- Runtime: `plugins/auth-sniffer/src/cli.ts`
## Deterministic Flow
1. Preflight browser and agentping status.
2. Select active CDP-capable browser (`--browser` overrides auto-select).
3. Kill active browser process set and wait until terminated.
4. Relaunch browser with CDP on explicit/free port.
5. Extract required `cookies`, `localStorage`, and `sessionStorage` keys.
6. Stop CDP browser, wait for shutdown, reopen normal browser.
7. Return structured result or structured error.
## Quick Commands
```bash
# Browser inventory (machine-readable)
auth-sniff --list-browsers --json
# Robot mode for a known service
auth-sniff --service twitter --robot --browser brave --json
# Custom extraction (cookie + storage keys)
auth-sniff \
--domains .x.com \
--cookie auth_token,ct0 \
--localStorageKeys=twid \
--sessionStorageKeys=auth_state \
--robot \
--browser brave \
--json
```
## Output Contract
- Success: `{ "ok": true, "data": { ... } }`
- Error: `{ "ok": false, "error": { "code", "message", "suggestions" } }`
- Exit codes:
- `0` success
- `1` not found
- `2` invalid args
- `3` runtime error
- `4` dependency missing
- `5` timeout
## Build + Emit
```bash
# Compile FlowMind -> SmartDown artifact
pnpm -C plugins/auth-sniffer run skills:compile
# Compile and emit skill to ~/.agents/skills/auth-sniffer/
pnpm -C plugins/auth-sniffer run skills:emit
```
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