Electron 42 went out of support when Electron 45 shipped on 2026-10-21 (Electron supports the latest three major versions). After this change the desktop app and Factory both run on a supported Electron version. The upgrade surfaced three Electron 45 behaviour changes, and each is fixed here.

What changed

• apps/desktop and apps/factory: electron 42.11.18 → 45.0.0. The lockfile only changes the Electron entries; 45.0.0 has the same dependencies as 42.
• Browser screenshots to the clipboard (browserHost.ts): Electron 44 removed clipboard.writeImage, so on 45 every browser-panel screenshot would throw. It now uses clipboard.write([new ClipboardItem({ "image/png": … })]).
• Phone and tablet browser sizes (browserHost.ts): on 45, enableDeviceEmulation({ screenPosition: "mobile" }) ignores the page's viewport tag, so a width=device-width page laid out 980px wide instead of 390px. The device size is now set with the DevTools protocol's Emulation.setDeviceMetricsOverride, which gives the same result on 42 and 45. enableDeviceEmulation remains the fallback if the page's debugger is taken. The debugger now stays attached while a device size is set, including with the System colour scheme.
• Smoke scripts: on 45, executeJavaScript rejects results it can't clone, such as React-managed elements ("An object could not be cloned"); 42 returned {} for them. The run helpers in the review-threads, chat-reference, prompt-commands, history and chat-shell smokes now map that rejection to true. The chat-shell capture retry also accepts UnknownVizError, 45's name for a surface that isn't ready yet.
• Patch changeset for both apps.

Why 45.0.0

45.1.0 is two days old and blocked by minimumReleaseAge. No advisories affect 45.0.0.

Other breaking changes checked (43–45)

Verification

• Desktop and factory typecheck and lint are clean against the Electron 45 types. Factory vitest: 124/124.
• Clipboard: a real Electron 45 round trip (capturePage → clipboard.write → clipboard.read()) returns image/png with a valid PNG signature. It also confirmed clipboard.writeImage is undefined on 45.
• Viewport: a minimal script reproduced 980×2121 on 45 and 390×844 on 42. With the change, test:browser-viewport passes all 96 cases on 45 (it was failing 48).
• I ran every non-packaged step of the desktop Windows workflow locally on 45:
  • Review threads, chat reference, prompt commands, history, chat shell and native browser, and native browser permissions all pass after the fixes.
  • Harness update fails locally on main with Electron 42 as well, so it's a local environment issue.
  • smoke.mjs stops locally at database is locked, also on main with 42. CI's Windows job passes it.
• Not run: electron-forge make, which CI doesn't run either. The next desktop release build should be checked.

Proved with real Electron 45 runs of the clipboard and viewport changes, plus the desktop workflow's smoke steps.

Created with Claude Opus 5.5 in Claude Code.

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