🤖 fix: change Electron appId to com.coder.mux

[ThomasK33]

Summary

Change the Electron Builder application identifier from com.mux.app to com.coder.mux.

Background

The current app ID uses the legacy com.mux.app identifier. This PR updates branding alignment to com.coder.mux.

Implementation

• Updated build.appId in package.json:
  • com.mux.app → com.coder.mux

Validation

• make static-check

Risks

Potentially breaking for existing installs. Changing Electron Builder appId can affect OS-level app identity and update continuity:

• macOS: bundle identifier (CFBundleIdentifier)
• Windows: AUMID / NSIS identity

Existing installations that were distributed with com.mux.app may require reinstall/migration handling instead of seamless in-place updates.

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[chatgpt-codex-connector]

Keep Electron appId stable across released builds

Changing build.appId changes the OS-level application identity (bundle ID/AUMID), so users already installed under com.mux.app can lose seamless in-place upgrade behavior and may end up with parallel installs or broken update continuity on macOS/Windows. This commit updates the identifier but does not include any migration strategy, so existing production installs are at risk during the next upgrade.

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[ThomasK33]

Thanks for the callout.

This appId change is intentional in this PR, and I’ve marked it as potentially breaking in the PR body. I agree this can break in-place update continuity for users already installed under com.mux.app.

Given that migration across OS-level app identity is a release/product decision (not a simple code-only fix), I’m pausing for maintainer direction on whether we should:

1. keep this change and ship with a one-time manual reinstall path, or
2. revert and keep com.mux.app for update continuity.