yichen-mac-wechat-dual-open

name

yichen-mac-wechat-dual-open

description

Create, inspect, repair, and polish a second WeChat app on macOS. Copy WeChat, change the bundle identifier, ad-hoc re-sign, launch the second instance, set Chinese language preferences, and recolor only the copied app icon from WeChat green to blue. Use when the user asks whether Mac WeChat dual-open methods are reliable, asks to double-open WeChat, fix WeChat-2 language/icon/cache issues, or make the second WeChat visually distinct without installing third-party injection tools.

Mac WeChat Dual Open

Create a second WeChat instance on macOS for running two accounts simultaneously.

Core Method

The underlying mechanism is simple — macOS distinguishes apps by their bundle identifier. By copying WeChat, changing the copy's bundle ID, and re-signing it locally, macOS treats the copy as a separate app that can run alongside the original:

1. Copy /Applications/WeChat.app to ~/Applications/WeChat-2.app.
2. Change the copy's CFBundleIdentifier (e.g., to com.tencent.xin2).
3. Re-sign the copy with codesign --force --deep --sign -.
4. Launch the copy via its executable directly.

No third-party injection tools or modified binaries required.

Prerequisites

• macOS 12+ with WeChat installed at /Applications/WeChat.app
• Python 3.10+ (system python works)
• Pillow (pip3 install Pillow) — required only for recolor-icon
• Xcode Command Line Tools (xcode-select --install) for codesign, iconutil, sips

Locating the Script

The helper script lives at scripts/wechat_dual_open.py relative to this skill directory. Different agents install skills to different paths. Construct the script path dynamically:

# Auto-detect skill directory
SKILL_DIR="$(dirname "$(find ~ -path '*/yichen-mac-wechat-dual-open/SKILL.md' -maxdepth 4 2>/dev/null | head -1)")"
SCRIPT="$SKILL_DIR/scripts/wechat_dual_open.py"

Quick Commands

python3 "$SCRIPT" status          # Check current state
python3 "$SCRIPT" create          # Create the second WeChat
python3 "$SCRIPT" set-language --languages zh-Hans en   # Set Chinese
python3 "$SCRIPT" recolor-icon --blue "#1296db"         # Blue icon
python3 "$SCRIPT" launch          # Start the second instance
python3 "$SCRIPT" repair          # Fix bundle id, signing, language, caches

Default paths (override with --source-app, --target-app, --bundle-id):

• Source: /Applications/WeChat.app
• Target: ~/Applications/WeChat-2.app
• Bundle ID: com.tencent.xin2

Workflow

1. Status first. Run status to see what already exists.
2. Create. If no second app exists, run create. This copies the app, changes the bundle ID, sets Chinese language, removes CFBundleIconName, re-signs, and registers with Launch Services.
3. Language. If the second instance opens in English, run set-language, then restart it.
4. Icon. Run recolor-icon to change the WeChat green to a user-chosen blue. The script handles both the outer AppIcon.icns and the embedded WeChatAppEx.app/.../app.icns, removes CFBundleIconName to avoid stale Assets.car entries, and sets a Finder custom icon when the Carbon-era tools (DeRez, Rez, SetFile) are available.
5. Launch. Run launch. The second WeChat should appear with its own login window. Pin it to the Dock separately from the original.

Reliability & Tradeoffs

This is not an official method. Rate it roughly 6.5–7 / 10 for reliability:

• Works on many macOS + WeChat version combinations.
• No code injection or third-party tweaks — easy to inspect and undo.
• Breaks after WeChat updates. Re-run create (or repair) after updating the original WeChat.
• Push notifications may be unreliable (APNs tied to original identity).
• Login state and Keychain are isolated per bundle ID.
• Ad-hoc signing may fail if WeChat adds stricter signature checks.

See references/reliability-and-risks.md for the full analysis.

Icon Pitfalls

WeChat stores icons in multiple locations. The script handles all of them:

Location	What it affects
Contents/Resources/AppIcon.icns	Main app icon
Contents/MacOS/WeChatAppEx.app/Contents/Resources/app.icns	Embedded runtime icon
Contents/Resources/Assets.car	Asset catalog (handled via CFBundleIconName removal)
Icon\r + Finder custom icon attr	Finder "Applications" view

If the user reports the icon is still green:

• They may be looking at /Applications/WeChat.app (the original), not ~/Applications/WeChat-2.app. Verify with open -R ~/Applications/WeChat-2.app.
• Dock caches per-process icons. Quit and relaunch WeChat-2.
• The Finder custom icon step requires DeRez/Rez/SetFile which may not exist on macOS 13+. The script skips gracefully — icns replacement is usually sufficient.

Safety

• Never modify /Applications/WeChat.app — all changes are scoped to the copy.
• Ask before deleting an existing second app. Prefer repair over delete/recreate.
• The codesign step must run before adding a Finder custom icon, otherwise macOS rejects the bundle with "resource fork, Finder information, or similar detritus not allowed".

References & Attribution

• Original tutorial by @koffuxu (2026-04, blog post: "Mac 微信双开最完美方案")
• Confirmed by @MinLiBuilds (2026-04)
• Icon recoloring uses HSV/HLS hue rotation via Pillow.
• Finder custom icon technique uses classic Carbon resource tools (DeRez/Rez).