fix(desktop): persist zoom level across routes

[katanumahotori]

Summary

Fixes Desktop zoom persistence so the selected zoom level behaves as an app-wide preference instead of a per-route Chromium value.

Chromium stores zoom for file://...index.html#/route entries separately, so Hermes Desktop could reset or vary zoom when switching sessions, opening settings, or landing on a different hash route. This PR stores the Desktop zoom level under Electron userData and reapplies it on window load/navigation events.

Changes

• Add zoom.json under Electron userData with { zoomLevel }.
• Clamp zoom level to Electron's supported [-9, 9] range.
• Route all menu and keyboard zoom changes through one persisted helper.
• Reapply the saved zoom level on dom-ready, did-finish-load, did-navigate, and did-navigate-in-page.
• Reapply on the next tick as well so Chromium's per-URL zoom restore cannot win a timing race.

Related

Fixes #38854.

Validation

• node --check apps/desktop/electron/main.cjs

I did not run the packaged Windows desktop build for this PR because Hermes Desktop is currently running locally, and the Windows package build can fail when release/win-unpacked DLLs are locked by the running app.

[teknium1]

Thanks for isolating the route-level zoom problem. The underlying gap remains relevant, but this draft needs a current-architecture salvage rather than a direct application.

Problems

• The only changed file, apps/desktop/electron/main.cjs, was removed by the TypeScript migration (39d09453f95e8aefc0c97e5d9b30ff341cae9ed8). Current zoom ownership is in apps/desktop/electron/main.ts:4754-4825.
• Current main deliberately scopes global UI zoom away from the pet overlay (apps/desktop/electron/main.ts:6968-6981). The draft's all-BrowserWindow application path would need to preserve that exclusion.
• The draft adds navigation-time behavior without a regression test. Current main still restores only on first load plus show/restore (apps/desktop/electron/main.ts:6975-6980) while the renderer uses HashRouter (apps/desktop/src/main.tsx:42).

Suggested changes

• Rework this through wireCommonWindowHandlers() and the existing zoom helpers, covering chat/session windows without enabling zoom for the pet overlay.
• Add a focused in-page navigation regression test.

Automated hermes-sweeper review.

[teknium1]

Closing as superseded — both halves of this design have since landed on main via other PRs:

• Main-process JSON zoom persistence (your zoom.json design): PR fix(desktop): persist zoom to JSON and save window state on first show (#56726) #66901 ships zoom-state.json as the primary store with localStorage as a migration mirror
• Restore on every load / across routes: PR fix(desktop): re-apply persisted zoom on every full load (#46429) #66989 re-applies the persisted zoom on every did-finish-load, covering route changes, reloads, and crash recovery

You had the right architecture — main-process file as the source of truth — before either of those landed; it just arrived via parallel salvages. Thanks for the work, and sorry it sat in draft long enough to be overtaken.