feat: write appVersion into the packaged app's package.json

[claude]

Requested by Samuel Attard · Slack thread

• I have read the contribution documentation for this project.
• I agree to follow the code of conduct that this project follows, as appropriate.
• The changes are appropriately documented (if applicable).
• The changes have sufficient test coverage (if applicable).
• The testsuite passes successfully on my local machine (if applicable).

Summarize your changes:

Before: the appVersion option was only stamped into executable metadata (rcedit/resedit on Windows, Info.plist on macOS). On Linux there is no such metadata, so app.getVersion() falls back to the packaged package.json — meaning --app-version=99 on Linux still gives app.getVersion() === "0.0" when the app's package.json has no version field, and a stale version field silently wins over --app-version.

After: the resolved appVersion is always written into the version field of the packaged app's package.json, so app.getVersion() returns the same value on every platform. When appVersion was inferred from package.json in the first place, the write is a no-op (and is skipped entirely if the value already matches, preserving the file's original formatting).

How: the write happens in the platform-agnostic App class in src/platform.ts — a new writeAppVersion() step runs in buildApp() after copyTemplate()/validation and before asar packing, so the updated package.json lands inside app.asar (or the app directory when asar is disabled). Only the copy in the staging directory is modified, never the user's source directory. The appVersion JSDoc in src/types.ts is updated accordingly, with unit tests in test/platform.spec.ts and end-to-end assertions in test/packager.spec.ts.

Closes #1331

---

Generated by Claude Code