fix(desktop): notify when a profile switch fails instead of silently reverting

[chelsealong]

What does this PR do?

Fixes the desktop profile switcher silently failing: clicking a profile shows the "Waking up …" overlay, then it just disappears and nothing switches, with no error and no way to tell what happened.

Related Issue

Fixes #89622

Root Cause

selectProfile() / newSessionInProfile() (apps/desktop/src/store/profile.ts) call ensureGatewayProfile(target) fire-and-forget (void ensureGatewayProfile(target)), and ensureGatewayProfile itself swallows a failed descriptor lookup:

})().catch(() => {
  // Descriptor lookup failed: the switch fails as a unit. Nothing was
  // published, so every atom still consistently describes the previous
  // profile; the user can retry the switch.
})

That "publish nothing on failure" behavior is correct (it's what #46651's regression test in profile.test.ts already locks in) — but it is also completely silent. When resolveConnectionForProfile/prepareGatewayForProfile reject (backend unreachable, profile deleted mid-dial, etc.), the ChatSwapOverlay "waking up" indicator (driven by $gatewaySwapTarget, cleared in the finally regardless of outcome) just fades out, $activeGatewayProfile never moves, and the caller never learns the switch was declined. From the user's side that reads exactly like #89622: "it says waking up... but it didn't actually switch."

Changes Made

• apps/desktop/src/store/profile.ts — ensureGatewayProfile's failure path now calls notifyError() (the app's existing top-center toast) with a new translated message, so a failed switch is visibly reported instead of silently reverting.
• apps/desktop/src/i18n/types.ts, apps/desktop/src/i18n/en.ts, apps/desktop/src/i18n/zh.ts — add the composer.profileSwitchFailed string (the two locales that declare the full Translations type directly; the other locales fall back to English via defineLocale).
• apps/desktop/src/store/profile.test.ts — new regression test asserting notifyError fires with the failing error when the descriptor fetch rejects.

How to Test

Commands run from apps/desktop:

npx vitest run --project ui src/store/profile.test.ts
npm run typecheck
npm run lint

Results:

• src/store/profile.test.ts: 16 passed (15 pre-existing + 1 new).
• A/B guard: with only the profile.ts hunk reverted (git checkout HEAD~1 -- apps/desktop/src/store/profile.ts apps/desktop/src/i18n/en.ts apps/desktop/src/i18n/types.ts), the new test notifies the user when a fire-and-forget switch fails (#89622) FAILS (expected "vi.fn()" to be called ... Number of calls: 0); all other tests in the file still pass.
• npm run typecheck: passed (tsc -p . --noEmit && tsc -p tsconfig.electron.json --noEmit && tsc -p tsconfig.e2e.json --noEmit).
• npm run lint: 0 errors, 129 pre-existing warnings (none in touched files).

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):)
• I searched for existing PRs to make sure this isn't a duplicate (checked feat(desktop): restore session when switching profiles #77957, fix(profiles): seed plugins/ for new profiles #88153, fix(desktop): allow switching primary profile back to default #86092, test(profiles): make profile tests Windows-locale safe #84024 — none address this silent-failure path)
• My PR contains only changes related to this fix (no unrelated commits, no dependency/lockfile changes)
• I've added a test for the change
• I've tested on my platform: Linux (CI-equivalent); this is UI-store logic exercised entirely through vitest, not platform-specific

Documentation & Housekeeping

• No config keys changed — N/A
• No architecture/workflow change — N/A
• Cross-platform: no OS-specific code — N/A

Disclosure

This change was prepared with AI assistance (Claude Code), including root-cause analysis of the swallowed rejection path, the fix, and the regression test. All commands above were run and their real output is reported here.

[alt-glitch]

This was generated by AI during triage.

Related: #89621 and #89609 also address silent declined desktop profile switches through different error-publication paths. #89621 is the earlier broader candidate because it also handles a wedged switch; please review the approaches together.

[teknium1]

Closing — the seams this PR hardens were rewritten during the resolution of #89622, and the specific failure it surfaces no longer exists.

Sequence on main: the atomic-publish series was reverted (#89785), profile switching was re-landed with fail-open semantics and an activation lease preventing mid-dial socket disposal (#89797), and the underlying release-build breakage turned out to be nanostores 1.4.0's @__NO_SIDE_EFFECTS__ annotation on batch() letting Rollup strip the switch publication from minified bundles — fixed by the 1.4.2 bump in #89875.

On the current code a switch cannot silently decline (the decline path is gone), and descriptor-lookup failures are logged rather than swallowed. If you see a switch-failure UX gap remaining on latest main — e.g. a user-visible toast rather than a console warning — a fresh PR against the current seams would be welcome. Thanks for the work here; the silent-failure framing was correct and informed the final design.