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Websites & UI (frontend)42k · #4707

competition-browser-persistence

Helps your agent analyze how websites store information in your browser. It investigates cookies and other data to understand how sessions work.

What it does

This tool helps understand how websites store information in your browser (like saved logins or preferences) and how this affects what you see or do online. It allows you to investigate and reproduce website behaviors based on this stored information.

When to use it

  • ✓When a website behaves differently after loading.
  • ✓To see how stored information (like logins) affects the experience.
  • ✓When investigating how a site works offline or stores data in the browser.

Example of what to ask your AI

“How does website X store my login and how does that affect what I see?”

Want more? Open the sections below.

How to use

The easiest way: copy the message below and paste it into Claude, ChatGPT, Cursor or any AI. It reads the skill and follows the instructions.

Skill link

https://github.com/zhaoxuya520/reverse-skill/blob/main/CTF-Sandbox-Orchestrator/competition-browser-persistence/SKILL.md

Ready-to-paste message

Use this skill to help me: https://github.com/zhaoxuya520/reverse-skill/blob/main/CTF-Sandbox-Orchestrator/competition-browser-persistence/SKILL.md Read the SKILL.md file at that link and follow its instructions for my task.
How it works

It examines where the site stores data (cookies, local storage, etc.) and how that data is used to change what the site shows or allows you to do. Then, it tries to recreate the exact path leading to a specific outcome.

Installation

Easiest way: copy the skill link and paste it into Claude, ChatGPT or Cursor asking it to follow the instructions.

In the terminal (Claude Code, Codex, Cursor), in your project folder:

npx skills add zhaoxuya520/reverse-skill --skill competition-browser-persistence

Or download just the file:

curl -L https://raw.githubusercontent.com/zhaoxuya520/reverse-skill/main/CTF-Sandbox-Orchestrator/competition-browser-persistence/SKILL.md -o SKILL.md
Technical content (original SKILL.md)

Original text by the author, straight from GitHub.

Competition Browser Persistence

Use this skill only as a downstream specialization after $ctf-sandbox-orchestrator is already active and has established sandbox assumptions, node ownership, and evidence priorities. If that has not happened yet, return to $ctf-sandbox-orchestrator first.

Use this skill when the decisive branch lives in browser-held state rather than only in visible HTML or backend source.

Reply in Simplified Chinese unless the user explicitly requests English.

Quick Start

  1. Identify the active persistence surface first: cookie jar, localStorage, sessionStorage, IndexedDB, Cache Storage, or service worker.
  2. Record origin, scope, domain, path, expiry, and key names before mutating state.
  3. Tie stored state to one concrete effect: request header, rendered branch, cached response, offline behavior, or hidden route access.
  4. Separate boot-time state from runtime-mutated state.
  5. Reproduce the smallest stateful sequence that reaches the decisive branch.

Workflow

1. Map Browser State Surfaces

  • Inspect cookies, storage buckets, service worker registrations, cache entries, and transient globals exposed during boot.
  • Record which origin, host, route, or feature flag each state item actually applies to.
  • Keep auth tokens, refresh material, CSRF state, cached responses, and feature toggles in separate evidence blocks.

2. Tie State To Runtime Behavior

  • Show how stored state becomes request headers, role derivation, route visibility, cached API data, or offline fallback behavior.
  • Compare clean-state and mutated-state runs with one variable changed at a time.
  • Distinguish UI-only state from backend-accepted state.

3. Reduce To The Decisive Persistence Chain

  • Compress the result to the smallest chain: initial page or login -> state persisted -> subsequent request or render branch -> resulting capability.
  • Keep extracted storage, service worker scripts, and replay steps tied to the same origin and route.
  • If the problem broadens into general web routing or worker behavior outside browser persistence, switch back to the broader web-runtime skill.

Read This Reference

  • Load references/browser-persistence.md for the browser-state checklist, service-worker checklist, and evidence packaging.

What To Preserve

  • Cookie attributes, storage keys, database names, cache keys, service worker scopes, and origin boundaries
  • The exact request or render effect caused by each decisive state item
  • Clean-state vs mutated-state reproduction steps for the smallest working path
FAQ

What are 'persistence surfaces'?

These are the places where the browser stores information for a website, such as cookies, local storage, session storage, and the IndexedDB database.

Why separate 'boot-time state' from 'runtime-mutated state'?

To better understand what causes a change: whether it was something already there when the page loaded or something the site changed while you were using it.

What does 'reduce to the decisive persistence chain' mean?

It means finding the smallest set of steps and stored information that explains a specific website behavior, to make analysis easier.

Details

Original description by the author

Internal downstream skill for ctf-sandbox-orchestrator. CTF-sandbox workflow for browser cookies, localStorage, sessionStorage, IndexedDB, Cache Storage, service workers, offline caches, and client-side session persistence. Use when the user asks to inspect browser state, replay cached auth or session behavior, explain why a page behaves differently after load, or trace how stored client state cha

repo: zhaoxuya520/reverse-skill

Popularity

GitHub stars
42k
Ranking position
#4707
License
MIT
Updated
9/22/2026

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