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Competition Web Runtime

Free

Specialized tool for web behavior and routing analysis.

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Free · Opens the source repo

What Competition Web Runtime does

The Competition Web Runtime skill is designed for users who need to analyze and debug web applications, particularly in the context of Capture The Flag (CTF) challenges. This skill must be used in conjunction with the $ctf-sandbox-orchestrator, which establishes the necessary sandbox environment and assumptions required for effective operation. Once the orchestrator is active, this skill allows for detailed inspection of web behavior, browser states, server routing, API interactions, and application flow backed by workers.

To utilize this skill, users should first map the active runtime by identifying hosts, paths, and storage mechanisms such as cookies and local storage. It emphasizes capturing real request flows and understanding the order of operations within the application. By focusing on one proven path before expanding the investigation, users can effectively trace middleware, authentication boundaries, and hidden routes, ensuring a thorough understanding of the web application's behavior.

This skill is particularly useful for developers and security researchers who are engaged in CTF competitions or need to debug complex web applications. It provides a structured approach to dissecting web interactions and understanding discrepancies between frontend and backend behavior. The skill's methodology encourages careful examination and validation of requests and responses, which is critical for uncovering hidden vulnerabilities or misconfigurations in web applications.

However, users should be aware that this skill is not a standalone solution and requires the prior establishment of a sandbox environment. It is not suitable for general web development tasks outside the CTF context or for those unfamiliar with the intricacies of web application routing and state management.

When to use it

Use this skill when you need to inspect web behavior, debug API interactions, or trace application flows in a CTF context.

When not to use it

This skill is not suitable for general web development tasks or if the `$ctf-sandbox-orchestrator` has not been established.

What you can build with it

Debugging API Interactions

Use this skill to trace API requests and responses, ensuring that the backend logic aligns with frontend behavior.

Analyzing Web Application Flows

Inspect the flow of data and requests through a web application to identify potential vulnerabilities or misconfigurations.

Capturing Real Request Flows

Record and analyze real request flows to understand the sequence of operations and troubleshoot issues effectively.

How to install Competition Web Runtime

View source

1. Install with the skills CLI

npx skills add zhaoxuya520/reverse-skill/competition-web-runtime --agent claude-code

2. Or install it manually

Download the skill folder and drop it into ~/.claude/skills/ for all projects, or .claude/skills/ to scope it to one repo. Restart Claude Code so it picks up the new skill.

Anthropic's agentic coding CLI, and the reference implementation of Agent Skills. Drop a skill folder into ~/.claude/skills and Claude Code loads it automatically whenever a task matches the skill's description. Claude Code docs

Inside SKILL.md

Written by zhaoxuya520

Competition Web Runtime

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 active challenge is primarily about web behavior, browser state, server routing, API order, or worker-backed application flow.

Reply in Simplified Chinese unless the user explicitly requests English.

Quick Start

  1. Assume the presented hosts, domains, and routes belong to the sandbox.
  2. Inspect entry HTML, boot scripts, runtime config, and route registration before trusting the visible UI.
  3. Capture one real request flow end-to-end before making broad claims from source.
  4. Check browser persistence and backend state together.
  5. Re-run the smallest flow with one variable changed.

Workflow

1. Map The Active Runtime

  • Identify active hosts, paths, proxies, containers, and workers.
  • Inspect cookies, localStorage, sessionStorage, IndexedDB, Cache Storage, and service workers.
  • Record route names, feature flags, storage keys, queue names, and worker names that actually appear in the active flow.

2. Capture The Real Request Order

  • Record exact host, path, query, headers, cookies, and body for decisive requests.
  • Compare successful and failing paths.
  • Treat UI gating as a hint, not proof of backend enforcement.

3. Expand Only After One Path Is Proven

  • Trace middleware order, handlers, auth/session boundaries, uploads, exports, and background jobs.
  • Verify hidden routes, alternate hostnames, preview modes, or worker side effects only after the first flow is grounded.

Read This Reference

  • Load references/routing-runtime.md for the detailed checklist, evidence packaging, and common web pitfalls.
  • If the task is specifically about SSR loaders, template context, hydration payloads, preview rendering, or render-layer enforcement drift, prefer $competition-template-render-path.
  • If the task is specifically about source maps, build manifests, chunk registries, emitted bundles, or recovering hidden runtime structure from served assets, prefer $competition-bundle-sourcemap-recovery.
  • If the task is specifically about GraphQL schemas, RPC manifests, persisted queries, generated clients, or contract-to-handler drift, prefer $competition-graphql-rpc-drift.
  • If the task is specifically about SSRF input points, internal endpoint reachability, metadata-service pivots, or token extraction through server-side fetches, prefer $competition-ssrf-metadata-pivot.
  • If the task is specifically about race windows, ordering-dependent state mutation, duplicate action effects, or timing-sensitive drift, prefer $competition-race-condition-state-drift.
  • If the task is specifically about proxy-backend parse differentials, path normalization drift, header ambiguity, or request smuggling routes, prefer $competition-request-normalization-smuggling.
  • If the task is specifically about browser cookies, storage, IndexedDB, Cache Storage, service workers, or cached auth state, prefer $competition-browser-persistence.
  • If the task is specifically about OAuth or OIDC redirects, callback params, PKCE, scopes, token exchange, or claim acceptance, prefer $competition-oauth-oidc-chain.
  • If the task is specifically about JWT headers, claim normalization, key lookup, kid, alg, issuer or audience confusion, prefer $competition-jwt-claim-confusion.
  • If the task is specifically about upload parsing, previews, archive extraction, converters, or deserialization chains, prefer $competition-file-parser-chain.
  • If the task is specifically about queue payloads, worker-only behavior, retries, cron drift, or async side effects, prefer $competition-queue-worker-drift.
  • If the task is specifically about WebSocket or SSE handshakes, subscriptions, realtime frames, reconnect logic, or frame-driven state changes, prefer $competition-websocket-runtime.
  • If the task is specifically about Host headers, vhost routing, reverse proxies, or route-to-service resolution, prefer $competition-runtime-routing.
  • If the only available evidence is a packet capture and the hard part is stream or protocol reconstruction, prefer $competition-pcap-protocol.

What To Preserve

  • Exact requests and responses that prove behavior
  • Concrete file paths, function names, route names, and storage keys
  • Queue payloads, worker names, or retry behavior when async processing matters

Frequently asked questions about Competition Web Runtime

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