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+<!--
+Derived from vercel-labs/agent-browser (skills/agent-browser/references/authentication.md).
+Copyright 2025 Vercel Inc. Licensed under Apache-2.0.
+Modified by Pythinker: local integration, formatting and adaptations.
+See THIRD-PARTY-NOTICES.md in the repository root for license and provenance.
+-->
+
+# Authentication Patterns
+
+Login flows, session persistence, OAuth, 2FA, and authenticated browsing.
+
+**Related**: [session-management.md](session-management.md) for state persistence details, [SKILL.md](../SKILL.md) for quick start.
+
+## Contents
+
+- [Import Auth from Your Browser](#import-auth-from-your-browser)
+- [Persistent Profiles](#persistent-profiles)
+- [Session Persistence](#session-persistence)
+- [Basic Login Flow](#basic-login-flow)
+- [Saving Authentication State](#saving-authentication-state)
+- [Restoring Authentication](#restoring-authentication)
+- [OAuth / SSO Flows](#oauth--sso-flows)
+- [Two-Factor Authentication](#two-factor-authentication)
+- [HTTP Basic Auth](#http-basic-auth)
+- [Cookie-Based Auth](#cookie-based-auth)
+- [Token Refresh Handling](#token-refresh-handling)
+- [Security Best Practices](#security-best-practices)
+
+## Import Auth from Your Browser
+
+The fastest way to authenticate is to reuse cookies from a Chrome session you are already logged into.
+
+**Step 1: Start Chrome with remote debugging**
+
+```bash
+# macOS
+"/Applications/Google Chrome.app/Contents/MacOS/Google Chrome" --remote-debugging-port=9222
+
+# Linux
+google-chrome --remote-debugging-port=9222
+
+# Windows
+"C:\Program Files\Google\Chrome\Application\chrome.exe" --remote-debugging-port=9222
+```
+
+Log in to your target site(s) in this Chrome window as you normally would.
+
+> **Security note:** `--remote-debugging-port` exposes full browser control on localhost. Any local process can connect and read cookies, execute JS, etc. Only use on trusted machines and close Chrome when done.
+
+**Step 2: Grab the auth state**
+
+```bash
+# Auto-discover the running Chrome and save its cookies + localStorage
+agent-browser --auto-connect state save ./my-auth.json
+```
+
+**Step 3: Reuse in automation**
+
+```bash
+# Load auth at launch
+agent-browser --state ./my-auth.json open https://app.example.com/dashboard
+
+# Or load into an existing session
+agent-browser state load ./my-auth.json
+agent-browser open https://app.example.com/dashboard
+```
+
+This works for any site, including those with complex OAuth flows, SSO, or 2FA -- as long as Chrome already has valid session cookies.
+
+> **Security note:** State files contain session tokens in plaintext. Add them to `.gitignore`, delete when no longer needed, and set `AGENT_BROWSER_ENCRYPTION_KEY` for encryption at rest. See [Security Best Practices](#security-best-practices).
+
+**Tip:** Combine with `--session-name` so the imported auth auto-persists across restarts:
+
+```bash
+agent-browser --session-name myapp state load ./my-auth.json
+# From now on, state is auto-saved/restored for "myapp"
+```
+
+## Persistent Profiles
+
+Use `--profile` to point agent-browser at a Chrome user data directory. This persists everything (cookies, IndexedDB, service workers, cache) across browser restarts without explicit save/load:
+
+```bash
+# First run: login once
+agent-browser --profile ~/.myapp-profile open https://app.example.com/login
+# ... complete login flow ...
+
+# All subsequent runs: already authenticated
+agent-browser --profile ~/.myapp-profile open https://app.example.com/dashboard
+```
+
+Use different paths for different projects or test users:
+
+```bash
+agent-browser --profile ~/.profiles/admin open https://app.example.com
+agent-browser --profile ~/.profiles/viewer open https://app.example.com
+```
+
+Or set via environment variable:
+
+```bash
+export AGENT_BROWSER_PROFILE=~/.myapp-profile
+agent-browser open https://app.example.com/dashboard
+```
+
+## Session Persistence
+
+Use `--session-name` to auto-save and restore cookies + localStorage by name, without managing files:
+
+```bash
+# Auto-saves state on close, auto-restores on next launch
+agent-browser --session-name twitter open https://twitter.com
+# ... login flow ...
+agent-browser close  # state saved to ~/.agent-browser/sessions/
+
+# Next time: state is automatically restored
+agent-browser --session-name twitter open https://twitter.com
+```
+
+Encrypt state at rest:
+
+```bash
+export AGENT_BROWSER_ENCRYPTION_KEY=$(openssl rand -hex 32)
+agent-browser --session-name secure open https://app.example.com
+```
+
+## Basic Login Flow
+
+```bash
+# Navigate to login page
+agent-browser open https://app.example.com/login
+agent-browser wait --load networkidle
+
+# Get form elements
+agent-browser snapshot -i
+# Output: @e1 [input type="email"], @e2 [input type="password"], @e3 [button] "Sign In"
+
+# Fill credentials
+agent-browser fill @e1 "user@example.com"
+agent-browser fill @e2 "password123"
+
+# Submit
+agent-browser click @e3
+agent-browser wait --load networkidle
+
+# Verify login succeeded
+agent-browser get url  # Should be dashboard, not login
+```
+
+## Saving Authentication State
+
+After logging in, save state for reuse:
+
+```bash
+# Login first (see above)
+agent-browser open https://app.example.com/login
+agent-browser snapshot -i
+agent-browser fill @e1 "user@example.com"
+agent-browser fill @e2 "password123"
+agent-browser click @e3
+agent-browser wait --url "**/dashboard"
+
+# Save authenticated state
+agent-browser state save ./auth-state.json
+```
+
+## Restoring Authentication
+
+Skip login by loading saved state:
+
+```bash
+# Load saved auth state
+agent-browser state load ./auth-state.json
+
+# Navigate directly to protected page
+agent-browser open https://app.example.com/dashboard
+
+# Verify authenticated
+agent-browser snapshot -i
+```
+
+## OAuth / SSO Flows
+
+For OAuth redirects:
+
+```bash
+# Start OAuth flow
+agent-browser open https://app.example.com/auth/google
+
+# Handle redirects automatically
+agent-browser wait --url "**/accounts.google.com**"
+agent-browser snapshot -i
+
+# Fill Google credentials
+agent-browser fill @e1 "user@gmail.com"
+agent-browser click @e2  # Next button
+agent-browser wait 2000
+agent-browser snapshot -i
+agent-browser fill @e3 "password"
+agent-browser click @e4  # Sign in
+
+# Wait for redirect back
+agent-browser wait --url "**/app.example.com**"
+agent-browser state save ./oauth-state.json
+```
+
+## Two-Factor Authentication
+
+Handle 2FA with manual intervention:
+
+```bash
+# Login with credentials
+agent-browser open https://app.example.com/login --headed  # Show browser
+agent-browser snapshot -i
+agent-browser fill @e1 "user@example.com"
+agent-browser fill @e2 "password123"
+agent-browser click @e3
+
+# Wait for user to complete 2FA manually
+echo "Complete 2FA in the browser window..."
+agent-browser wait --url "**/dashboard" --timeout 120000
+
+# Save state after 2FA
+agent-browser state save ./2fa-state.json
+```
+
+## HTTP Basic Auth
+
+For sites using HTTP Basic Authentication:
+
+```bash
+# Set credentials before navigation
+agent-browser set credentials username password
+
+# Navigate to protected resource
+agent-browser open https://protected.example.com/api
+```
+
+## Cookie-Based Auth
+
+Manually set authentication cookies:
+
+```bash
+# Set auth cookie
+agent-browser cookies set session_token "abc123xyz"
+
+# Navigate to protected page
+agent-browser open https://app.example.com/dashboard
+```
+
+## Token Refresh Handling
+
+For sessions with expiring tokens:
+
+```bash
+#!/bin/bash
+# Wrapper that handles token refresh
+
+STATE_FILE="./auth-state.json"
+
+# Try loading existing state
+if [[ -f "$STATE_FILE" ]]; then
+    agent-browser state load "$STATE_FILE"
+    agent-browser open https://app.example.com/dashboard
+
+    # Check if session is still valid
+    URL=$(agent-browser get url)
+    if [[ "$URL" == *"/login"* ]]; then
+        echo "Session expired, re-authenticating..."
+        # Perform fresh login
+        agent-browser snapshot -i
+        agent-browser fill @e1 "$USERNAME"
+        agent-browser fill @e2 "$PASSWORD"
+        agent-browser click @e3
+        agent-browser wait --url "**/dashboard"
+        agent-browser state save "$STATE_FILE"
+    fi
+else
+    # First-time login
+    agent-browser open https://app.example.com/login
+    # ... login flow ...
+fi
+```
+
+## Security Best Practices
+
+1. **Never commit state files** - They contain session tokens
+
+   ```bash
+   echo "*.auth-state.json" >> .gitignore
+   ```
+
+2. **Use environment variables for credentials**
+
+   ```bash
+   agent-browser fill @e1 "$APP_USERNAME"
+   agent-browser fill @e2 "$APP_PASSWORD"
+   ```
+
+3. **Clean up after automation**
+
+   ```bash
+   agent-browser cookies clear
+   rm -f ./auth-state.json
+   ```
+
+4. **Use short-lived sessions for CI/CD**
+   ```bash
+   # Don't persist state in CI
+   agent-browser open https://app.example.com/login
+   # ... login and perform actions ...
+   agent-browser close  # Session ends, nothing persisted
+   ```