fix(auth): sign the desktop app in when the magic-link email opens in a browser - #2683
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… a browser The desktop magic-link handoff was dead on both ends: - Web: the dashboard only fired pagespace://auth-exchange from inside the Electron shell, but the emailed link always opens in the system browser, so the deep link never fired and the desktop app stayed signed out. - Desktop: the L9 hardening rejects any auth-exchange deep link unless a desktop-initiated flow is in progress, and the magic-link flow never began one — unlike OAuth/passkey, which both do. Fix follows the passkey pattern: MagicLinkForm begins an exchange (fire-and-forget, after a successful send) when it runs in the shell, and the dashboard hook fires the deep link from any browser. Acceptance is still bound to a desktop-initiated flow via the 10-minute flow-in-progress gate; the in-shell state-echo path is unchanged.
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📝 WalkthroughWalkthroughThe magic-link form now starts the Electron exchange flow after a successful send when the bridge exists. Exchange-code extraction no longer requires desktop-platform detection. Tests cover desktop success, send failure, web behavior, and missing parameters. ChangesDesktop exchange flow
Priority: ⬇️ Low Estimated code review effort: 3 (Moderate) | ~20 minutes Change: Bug fix Sequence Diagram(s)sequenceDiagram
participant MagicLinkForm
participant ElectronAuthBridge
participant ElectronMainProcess
MagicLinkForm->>ElectronAuthBridge: beginExchange()
ElectronAuthBridge->>ElectronMainProcess: start exchange acceptance window
Merge Risk: 🟡 Moderate · up to If desktop exchange startup fails, users are told to check their email even though the resulting authentication link cannot complete. Handle that failure before merging. 🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
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Inline comments:
In `@apps/web/src/components/auth/MagicLinkForm.tsx`:
- Line 161: Update the desktop exchange flow in MagicLinkForm so beginExchange
is awaited before setting sent or showing success; treat rejected or null
results as retryable errors, preserve the existing error state, and only confirm
success after a flow starts.
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apps/web/src/components/auth/MagicLinkForm.tsxapps/web/src/components/auth/__tests__/MagicLinkForm.test.tsxapps/web/src/hooks/__tests__/useDesktopExchangeHandler.test.tsapps/web/src/hooks/useDesktopExchangeHandler.ts
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…lly starting beginExchange can reject (IPC failure) or resolve null (untrusted sender — the main process records no flow). Both were discarded: the form showed the sent confirmation regardless, and the later pagespace://auth-exchange link then hit the L9 gate with no pending flow and was rejected, leaving the desktop app signed out despite the confirmation. Await the bridge call before confirming; a rejection or null now puts the form back on the input view with a retryable error. A deferred-promise test pins the ordering (no confirmation while the call is pending), and the rejection/null cases assert the retryable error and a re-enabled submit.
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Follow-up fix pushed (359565d): Now the form awaits the call before confirming: rejection or null returns to the input view with a retryable desktop error (submit re-enabled, no cooldown), and the sent confirmation appears only once the flow is recorded. A deferred-promise test pins the ordering; the rejection/null cases assert the error path. |
1 participant
Problem
Requesting a magic link from the desktop app never signed the desktop app in. The user got a web session in whatever browser opened the email; the Electron app stayed signed out.
Two independent defects, both verified against the code:
Break 1 (web side). The dashboard only fired the
pagespace://auth-exchange?code=...deep link inside the Electron shell —extractDesktopExchangeCodebailed unlesswindow.electronexisted (apps/web/src/hooks/useDesktopExchangeHandler.ts). But the emailed link is always anhttps://.../api/auth/magic-link/verify?token=...URL (magic-link-adapters.ts builds universal links for iOS/Android only), so it opens in the system browser, where the deep link never fired. A test even pinned the broken behavior ("returns null on web even with desktopExchange param").Break 2 (desktop side). Since the L9 hardening, the main process rejects any
auth-exchangedeep link unless a desktop-initiated auth flow is in progress (apps/desktop/src/main/deep-links.ts, auth-exchange-state.ts). The magic-link flow never began one:auth:begin-exchangewas only invoked by the dashboard hook that cannot run in a browser, andauth:open-external(which does begin a flow) is used only by OAuth/passkey.The verify route's own comment contradicted the gate: "its handoff has always ridden the emailed GET, so any browser that opens a desktop-bound link..." (verify/route.ts).
Fix
Follows the passkey pattern — smallest change that restores the flow without weakening L9:
MagicLinkFormcallswindow.electron.auth.beginExchange()fire-and-forget after a successful send, when running in the shell. The main process records the flow; the state is not echoed (the emailed link opens outside the shell, so it could not carry it back anyway).useDesktopExchangeHandlerdrops theisDesktopPlatform()gate — any browser with adesktopExchangeparam firespagespace://auth-exchange?code=.... The in-shellbeginExchange()state-echo path is preserved unchanged.Acceptance is still bound to a desktop-initiated flow: the 10-minute flow TTL comfortably covers the 5-minute magic-token and exchange-code TTLs, and a stateless deep link is accepted only while a flow is in progress — the same
flow-in-progress-no-statebranch the passkey flow already relies on.Testing
useDesktopExchangeHandler.test.ts: the web case now asserts the code IS returned in a plain browser (was pinned to null); desktop and missing-param cases unchanged; the now-unusedisDesktopPlatformmock removed.MagicLinkForm.test.tsxadds a "desktop exchange flow" suite: flow begun after a successful send, NOT begun when the send fails (no stray acceptance window), and no-op on web.bun run --filter 'web' test(both suites, 16 tests)bun run typecheckbun run --filter 'web' lintKnown tradeoff
If the user takes longer than the 10-minute flow TTL to click the email link, the desktop app shows the L9 "Unexpected sign-in request was blocked" error instead of silently ignoring the link — the same window the passkey flow has. Re-requesting the link starts a fresh flow.
Follow-up (not in this PR)
Coder shell threading: an external browser cannot detect the PageSpace Coder variant, so
buildDesktopExchangeDeepLinkdefaults topagespace://. Coder users clicking the emailed link in a browser may land in the wrong app (or nowhere). Threading the shell through send → token metadata → redirect is a separate change, as is the shared cross-device wart (request from desktop, click on phone → custom scheme silently no-ops, phone still gets a web session) that the OAuth bridge already accepts.Summary by CodeRabbit
New Features
Bug Fixes