build(electron): upgrade the Electron runtime from 39 to 44

[mrsibe]

What

One manifest line: electron ^39.4.0 → ^44.5.0 (lockfile resolves 44.5.0).

No application code changes were required.

Why now

Electron supports only the newest three stable majors. 39 is outside that window, so it no longer receives Chromium / V8 / Node security fixes. 44.5.0 is the current stable (45 is not stable yet). Electron 44 also moves the runtime onto Node 24, which matches the Node 24 that CI and CONTRIBUTING.md already require.

Breaking-change review (Electron 40 → 44)

Checked the official breaking-changes.md against every Electron API this app reaches (ipcMain, BrowserWindow, net.fetch, protocol.handle, shell.openExternal/openPath, dialog, Menu, app.*, webContents.*):

Change	Applies here?
44 — clipboard rearchitected + removed from renderer	No. The only clipboard call is navigator.clipboard.writeText in MessageItem.tsx, not the electron module.
44 — macOS 12 dropped; Windows ia32 / Linux armv7l dropped	No. No ia32/armv7l packaging targets.
44 — app.isUnityRunning() removed; login-item attributes removed	No. Neither is used.
44 — ANGLE statically linked (libEGL/libGLESv2 no longer shipped)	No. The app does not ship or swap those.
43 — dialog defaultPath now defaults to Downloads	Yes, behavior-only. Flagged below.
42 — macOS notifications require code signing	No. No Notification usage.
42 — Session.clearStorageData({ quotas }) removed	No such call.
41 — PDFs render in the same WebContents	No. PDFs are parsed by pdfjs-dist, not Chromium's viewer.
42 — electron no longer self-downloads in postinstall	Yes, operational. Flagged below.

Verification (Linux x64, WSL2)

Command	Result
npm run typecheck	clean
npm test	469/469 pass
npm run build:unpack && npm run smoke:packaged	29 checks pass

The packaged run confirms the native surface rebuilt for the new ABI:

electron 44.5.0, bundled node 24.21.0, modules ABI 149
[SmokeTest] ok   better-sqlite3 opened the database and loaded the sqlite-vec extension
[SmokeTest] ok   sqlite-vec reports version v0.1.7-alpha.2
[SmokeTest] ok   FTS5 is available and ranks: sqlite 3.53.2, ENABLE_FTS5 flag present
[SmokeTest] ok   @huggingface/transformers and onnxruntime-node load
[SmokeTest] PASS - 29 checks passed

@electron/rebuild rebuilt better-sqlite3 for ABI 149 without falling back to a source compile problem. macOS/Windows packaging is left to verify.yml + release.yml.

Two behavior changes to be aware of (not failures)

1. Electron 42 stopped downloading the binary in the electron package's postinstall. npm ci no longer populates node_modules/electron/dist. I verified npm run build (electron-vite) does not need the binary, electron-builder fetches its own copy, and npm run dev / npm run eval fetch it on first run. No repo change needed, but first-run dev now downloads ~150 MB instead of it happening at install time.
2. Electron 43 makes dialog.showOpenDialog/showSaveDialog default defaultPath to Downloads instead of the OS's last-used directory. The app passes no defaultPath, so dialogs now start in Downloads and the OS no longer remembers the last directory. Calling this out explicitly — happy to add remembered-directory handling as a follow-up if that is wanted, but it does not belong in an Electron bump.

Relationship to the sqlite-vec PR

Independent. It touches a different package.json line, but both PRs edit package-lock.json, so whichever merges second needs a lockfile rebase. The smoke output above intentionally shows the old sqlite-vec (v0.1.7-alpha.2) because this branch is based on main.

Rollback

Revert the one manifest line and regenerate the lockfile. No schema, storage format, or app code changed, so a rollback needs no data migration.