Electron App Extract#

Extracts resources and code from an installed Electron app's app.asar. When a .js.map is present, restores the original source files from the embedded sourcesContent; otherwise formats the minified code with Prettier. Source-map paths are resolved relative to the .js.map file first, so bundled paths like ../../src/main.ts restore to readable paths such as restored/src/main.ts instead of hashed placeholders. Always skips node_modules. Works on macOS and Windows.

User Input Tools#

When this skill prompts the user, follow this tool-selection rule (priority order):

1. Prefer built-in user-input tools exposed by the current agent runtime — e.g., AskUserQuestion, request_user_input, clarify, ask_user, or any equivalent.
2. Fallback: if no such tool exists, emit a numbered plain-text message and ask the user to reply with the chosen number/answer for each question.
3. Batching: if the tool supports multiple questions per call, combine all applicable questions into a single call; if only single-question, ask them one at a time in priority order.

Concrete AskUserQuestion references below are examples — substitute the local equivalent in other runtimes.

Script Directory#

Scripts in scripts/ subdirectory. {baseDir} = this SKILL.md's directory path. Resolve ${BUN_X} runtime: if bun installed → bun; if npx available → npx -y bun; else suggest installing bun. Replace {baseDir} and ${BUN_X} with actual values.

ScriptPurposescripts/main.tsApp discovery + asar extraction + source-map restoration + Prettier formatting

When to use#

Use this skill whenever the user wants to look inside an installed Electron application or inspect its bundled code. Trigger phrases include:

• "extract Electron app", "decompile this Electron app", "unpack app.asar"
• "show me the source of ", "look inside ", "how is built"
• "get the source code of Codex / Cursor / Discord / Slack / VS Code / Notion / Obsidian / ChatGPT desktop"
• "提取 Electron 应用", "看 的源码", "反编译 Electron", "解包 app.asar", "还原 source map"

Both app name (e.g., Codex) and absolute path (e.g., /Applications/Codex.app, a .asar file, or a Windows install dir) are accepted. The script handles discovery for both platforms.

Workflow#

1. Determine the input. Ask the user for the app name or path if they haven't given one. If they want a custom output directory, ask for that too.

2. Run the script.

bash

${BUN_X} {baseDir}/scripts/main.ts "<app>" [--output <dir>] [--asar <path>] [--force]

Start with --dry-run first if you're unsure whether discovery will find the right bundle — it prints the resolved paths and exits without touching the filesystem.

3. Handle the result.

• Success → report the output paths and the counts (extracted / restored / formatted).
• Multiple matches → the script lists candidates and exits non-zero. Show the user the candidates, ask which one to use (via AskUserQuestion or the runtime equivalent), then re-run with the chosen absolute path.
• Existing non-empty output dir → the script refuses without --force. Ask the user whether to overwrite ( --force) or pick a new --output path.
• Unsupported platform / no match → suggest passing --asar /full/path/to/app.asar if the user knows where the bundle lives.

4. Point the user at the result. The default output dir is ~/Downloads/<AppName>-electron-extract/. The most interesting subdirectory depends on what was found:

• restored/ exists → the original source tree was reconstructed from .js.map files; this is what to read first.
• Only extracted/ exists (no maps) → the JS/CSS in extracted/ was Prettier-formatted in place; read from there.

Source-map path restoration#

The script should preserve original source names and directory structure as much as the source map allows:

• Resolve each sources[] entry with sourceRoot when present, then relative to the .js.map file's directory inside extracted/.
• Collapse normal bundler-relative paths into the restored project tree. For example, .vite/main/index.js.map + ../../src/main.ts becomes restored/src/main.ts.
• If a source path climbs above extracted/, keep the readable remaining path under restored/ instead of hashing it. For example, .vite/main/index.js.map + ../../../shared/src/lib/foo.ts becomes restored/shared/src/lib/foo.ts.
• Strip URL/query decorations from source names, including common webpack://, file://, and ?loader suffixes.
• Use restored/__unknown/<hash>.<ext> only when the source name is empty or cannot be reduced to a safe file path.
• Continue skipping node_modules and webpack/runtime/* entries; these are bundler/runtime noise, not app sources.

Usage#

bash

# Extract by app name (default output: ~/Downloads/Codex-electron-extract/)
${BUN_X} {baseDir}/scripts/main.ts Codex

# Extract by absolute path (works for .app bundles, install dirs, or .asar files)
${BUN_X} {baseDir}/scripts/main.ts "/Applications/Visual Studio Code.app"
${BUN_X} {baseDir}/scripts/main.ts "C:\Users\you\AppData\Local\Programs\codex"
${BUN_X} {baseDir}/scripts/main.ts --asar /Applications/Codex.app/Contents/Resources/app.asar Codex

# Custom output
${BUN_X} {baseDir}/scripts/main.ts Codex --output ~/work/codex-source

# Preview discovery without writing anything
${BUN_X} {baseDir}/scripts/main.ts Codex --dry-run

# Overwrite an existing output dir
${BUN_X} {baseDir}/scripts/main.ts Codex --force

# Machine-readable result (one JSON line on stdout)
${BUN_X} {baseDir}/scripts/main.ts Codex --json

Options#

OptionShortDescriptionDefault<app>App name or absolute path. Required unless --asar is given.—--output``-oOutput directory~/Downloads/<AppName>-electron-extract``--asarOverride the resolved .asar pathauto-discovered--force``-fAllow writing into a non-empty existing output dirfalse--skip-formatSkip Prettier formattingfalse--skip-restoreSkip source-map restorationfalse--no-unpackedDon't copy app.asar.unpacked/ alongsidefalse--dry-runPrint resolved paths and exit without writingfalse--jsonEmit one JSON-line summary on stdout (suppresses normal output)false

Output layout#

text

~/Downloads/<AppName>-electron-extract/
├── extract-report.json          # JSON summary: counts, warnings, resolved paths
├── extracted/                   # raw asar contents (JS/CSS Prettier-formatted when no map)
│   └── ...                      # node_modules left untouched (skipped from format)
├── extracted.unpacked/          # copied from <asar>.unpacked/ if present
│   └── ...                      # native modules (.node), large assets
└── restored/                    # only present if at least one .js.map was usable
    └── <original/source/tree>   # rebuilt from sourcesContent in each .js.map

Notes#

• node_modules is always skipped — both for source-map restoration and Prettier formatting — because vendored dependencies are noise when inspecting an app.
• Source-map restoration only works when the .js.map embeds sourcesContent. This is the common case for modern bundlers (webpack, esbuild, Vite, rollup). If a map references external .ts/ .js files without embedding them, that map is skipped and the corresponding .js is Prettier-formatted instead. Skipped maps are listed in extract-report.json under warnings.
• Readable paths over hashes — don't treat ../ segments in source-map paths as automatically unsafe. First resolve them from the map location and then sanitize the final output path so it still stays under restored/. Hash fallback is only for unusable source names.
• App discovery searches /Applications + ~/Applications on macOS, and %LOCALAPPDATA%\Programs, %PROGRAMFILES%, %PROGRAMFILES(X86)%, %APPDATA% on Windows. If discovery finds multiple matches, the script exits and lists them — re-run with an absolute path. On Linux or other platforms, pass --asar /path/to/app.asar explicitly.
• Safety — the script refuses to write to /, the user home directly, or the current working directory, and refuses to populate an existing non-empty output dir without --force.
• No global installs — @electron/asar and prettier are resolved on-the-fly via npx -y. First run will be slower while npx caches them.