What is mcp-js-reverse-playbook?

A workflow guide for investigating browser JavaScript when you need to understand how a page creates request parameters. It covers observing pages, collecting evidence, recreating code locally, and simplifying confusing scripts.

Locating the scripts and functions behind a request, capturing runtime values, rebuilding the process in Node.js, adding only evidence-based browser replacements, and recording results.

It provides an evidence-led process for tracing signatures, encryption parameters, and other request fields instead of guessing how the page works.

mcp-js-reverse-playbook — Skill for Codex by Junjianxin

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add Junjianxin/jjx-js-reverse-mcp --skill mcp-js-reverse-playbook

Clone the repo

git clone --depth 1 https://github.com/Junjianxin/jjx-js-reverse-mcp

Made for: Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/junjianxin/jjx-js-reverse-mcp/mcp-js-reverse-playbook/github.svg)](https://agentmods.dev/skills/junjianxin/jjx-js-reverse-mcp/mcp-js-reverse-playbook)

Your own site

<a href="https://agentmods.dev/skills/junjianxin/jjx-js-reverse-mcp/mcp-js-reverse-playbook"><img src="https://agentmods.dev/badge/skills/junjianxin/jjx-js-reverse-mcp/mcp-js-reverse-playbook/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/junjianxin/jjx-js-reverse-mcp/mcp-js-reverse-playbook"><img src="https://agentmods.dev/badge/skills/junjianxin/jjx-js-reverse-mcp/mcp-js-reverse-playbook.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,142 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin 100% copy Near-identical to another mod in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00060	$0.01142
Opus 5.5	$0.00024	$0.00457
Sonnet 5.5	$0.00012	$0.00228
Haiku 4.5	$0.00006	$0.00114

Measured 2mo ago against content hash 9c00fa5c6ce3, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

mcp-js-reverse-playbook scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

100% identical to mcp-js-reverse-playbook — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/mcp-js-reverse-playbook/SKILL.md · 134 lines

How it starts

The opening of the file, as written. The whole thing — 134 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MCP 前端 JS 逆向作业规范

核心原则

Observe-first
Hook-preferred
Breakpoint-last
Rebuild-oriented
Evidence-first

先页面观察，再最小化采样，再做本地补环境，不要跳过取证直接猜环境。

目标场景

默认主场景是：

定位接口签名、加密参数、关键请求字段
在页面里确认哪个请求、哪个脚本、哪个函数参与参数生成
导出本地复现材料
在 Node 里按“代理 env log + first divergence + 最小因果单元”补环境跑通
跑通后再做 AST 去混淆、VMP 插桩或逻辑提纯

五阶段工作流

1. Observe

目标：

先确认目标请求、相关脚本、候选函数，不猜环境。

默认入口：

references/automation-entry.md
references/mcp-task-template.md

必须产出：

目标请求
initiator 线索
可疑脚本 URL / scriptId
初始 task artifact

2. Capture

目标：

对目标请求做最小侵入采样，拿到参数样例、调用顺序、运行时证据。

规则：

优先 fetch/xhr hook
如果目标发生在首屏初始化、首个请求前参数装配、页面首次执行阶段，先用 inject_preload_script 挂早期采样或补环境脚本
命中后先看 summary，再按需看 raw
Hook 不足时再考虑断点

3. Rebuild

目标：

把页面证据导出为本地可迭代的 Node 复现工程。

参考：

references/local-rebuild.md
references/task-artifacts.md

规则：

本地补环境必须以页面观测证据为依据
不允许空想式补 window/document/navigator/crypto/storage

4. Patch

目标：

按代理日志和 first divergence 驱动补环境，直到本地脚本能稳定跑出目标参数。

规则：

先读代理 env log，再记录当前 first divergence
一次只做一个补丁决策，不是机械地一次只改一个属性
一个补丁决策对应一个最小因果单元：值 / 函数壳 / 返回对象 / 最小对象契约
diff_env_requirements 仅作辅助，不替代代理日志
每次补丁后立即复测，并记录 first divergence 是否前移
每次补丁都写入 task artifact

5. DeepDive

目标：

本地跑通后，再做去混淆、VMP、控制流还原、业务逻辑提纯。

规则：

如果当前任务只是出签名，这一阶段可以降级
如果要长期复用算法链路，这一阶段必须做

执行要求

所有重要步骤都要写入本地 task artifact
如果无法解释为什么调用某个工具，就不要调用
输出必须满足 references/output-contract.md
失败时按照 references/fallbacks.md 回退
参数默认值按 references/tool-defaults.md
skills/references/cases/* 只允许抽象 case（映射/判定口径）
站点级可复用流程统一维护在 scripts/cases/*，不要把实操工作流写回 skills/references/cases/*
新增正式文档时遵循仓库分层：规则/模板放 docs/reference/，人类教程放 docs/guides/，公开参数索引更新 scripts/cases/README.md

必读引用

自动化入口：references/automation-entry.md
参数默认值：references/tool-defaults.md
任务输入模板：references/task-input-template.md
MCP 专用任务编排：references/mcp-task-template.md
任务产物：references/task-artifacts.md
本地复现：references/local-rebuild.md
补环境：references/env-patching.md、references/node-env-rebuild.md
插桩：references/instrumentation.md
AST 去混淆：references/ast-deobfuscation.md
回退：references/fallbacks.md
输出契约：references/output-contract.md
案例库：references/cases/

Read the full file on GitHub · 134 lines

Files

What ships with it

18 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 134 lines · 60 tokens per session scan A 9c00fa5c6ce3

Subscribe to this mod's changes

mcp-js-reverse-playbook is a skill published in the GitHub repository Junjianxin/jjx-js-reverse-mcp (2 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 60 tokens to every session and 1,142 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to mcp-js-reverse-playbook, differing in 0 lines, and is treated as a copy.

Browser automation Debugging

mcp-js-reverse-playbook next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
mcp-js-reverse-playbookJunjianxin/jjx-js-reverse-mcp	Skill	2	2mo ago	Apache-2.0	A	60	Codex
chrome-devtools-cliChromeDevTools/chrome-devtools-mcp	Skill	55k	yesterday	Apache-2.0	A	31	Claude Code
opencli-autofixjackwener/OpenCLI	Skill	31k	yesterday	Apache-2.0	A	61	Claude Code
chrome-performance-optimizerchromium/chromium	Skill	25k	yesterday	BSD-3-Clause	A	119	Claude Code, Codex
nullawaychromium/chromium	Skill	25k	yesterday	BSD-3-Clause	A	43	Claude Code, Codex
reenable-testchromium/chromium	Skill	25k	yesterday	BSD-3-Clause	A	85	Claude Code, Codex
bisectchromium/chromium	Skill	25k	yesterday	BSD-3-Clause	A	52	Claude Code, Codex