Add CLAUDE.md with codebase guidance for AI assistants

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Purpose
+
+This repository contains patches for [Charles Web Debugging Proxy](https://www.charlesproxy.com/) that bypass the license-check mechanism. Each versioned subdirectory (e.g. `4.2.7/`) contains:
+- A `charles.jar` – the pre-patched drop-in replacement for Charles's own JAR
+- A `README.md` – the manual hack script for that version
+
+## How the Hack Works
+
+Charles embeds a single obfuscated license-gate class (e.g. `GPSz`, `slZe`, `WNzU`, `oFTR`, `Dheu`) inside `charles.jar` under `com/xk72/charles/`. Each version uses a **different** class name and method signatures, but the interface is always the same:
+
+| Return type | Purpose | Patched return value |
+|-------------|---------|----------------------|
+| `boolean`   | Is licensed / is trial expired? | `true` |
+| `String`    | Registered name / organization | `"Administrator"` or a URL |
+| `String(String name, String key)` | Validate a registration key | `null` (disables key checks) |
+
+The patch replaces this class inside the official JAR using `javac` + `jar -uvf`.
+
+## Adding Support for a New Charles Version
+
+1. **Identify the license class name** for the target version by decompiling `charles.jar` (e.g. with `jadx` or `cfr`) and finding the class in `com.xk72.charles` that has the boolean/String method pattern above.
+
+2. **Create the version directory** and write the hack script following the pattern in any existing `README.md`. Key variables to update: class name, method names, the version number in the download links.
+
+3. **Compile and patch** (Java 1.8 required for 4.2.6+):
+   ```bash
+   export JAVA_HOME=`/usr/libexec/java_home -v 1.8`   # macOS; skip on Linux if java 8 is default
+   charles=/Applications/Charles.app/Contents/Java/charles.jar
+   dir=charleshack
+
+   mkdir $dir && cd $dir
+   # Write <ClassName>.java with the patched class (see README for template)
+   javac -encoding UTF-8 <ClassName>.java -d .
+   jar -uvf $charles com/xk72/charles/<ClassName>.class
+   cd .. && rm -rf $dir
+   ```
+
+4. **Commit the patched JAR** to the new version directory. The `.gitignore` excludes `*.class` files, so only the final `.jar` should be committed.
+
+## Repository Conventions
+
+- **One directory per Charles version** – named exactly after the version string (e.g. `4.2.7`).
+- Every version directory must contain both `charles.jar` and `README.md`.
+- The root `README.md` lists supported versions; update it when adding a new one.
+- Java `.class` files are gitignored; never commit them.
+- 4.2.6 and later require the `JAVA_HOME` export to target Java 1.8 before running `javac`; earlier versions do not need this.