fix(desktop): retry transient bearer bootstrap and degrade on session fetch failure

[jamesvillarrubia]

What Changed

The main process now retries the desktop bearer exchange (/oauth/token over loopback) when it fails transiently, instead of failing the app's launch on the first error.

• DesktopLocalEnvironmentAuth.getBearerToken retries every 500 ms for up to 15 s. That is the same budget the renderer's cookie bootstrap (retryTransientBootstrap) already uses.
• Retryable: undeclared 502/503/504 responses, transport failures (RemoteEnvironmentAuthFetchError), and request timeouts. Anything else, such as a rejected credential (401), a bad request, or a server error, fails on the first attempt.
• An outer 15 s timeout bounds the whole exchange, including a request still in flight at the deadline.

Why

On launch the renderer asks the main process for a bearer token. The main process exchanged the desktop bootstrap credential once, so a single 503, refused connection, or reset while the backend was still settling became DesktopLocalEnvironmentAuthSessionBootstrapError, and the app opened to the root error view. This is reported on macOS 26 and 27, and on current nightlies (#12918).

The exchange can be retried safely: the desktop bootstrap credential is reusable within its window (#16275), and it is computed once before the retries.

Tests

DesktopLocalEnvironmentAuth.test.ts:

• a backend answering 503 twice is retried until the token arrives;
• a rejected credential (401) fails after one request.

Each fails if the classifier is reverted or made to retry everything.

Maintainer note

Merged current main and reworked on top of @jamesvillarrubia's original commits:

• The classifier now matches on the request error union's tags instead of probing untyped fields; failures are already normalized into that union.
• I dropped the renderer fallback. When the session fetch failed it showed the pairing form, which on desktop asks for a token the user does not have. With the exchange retrying, the root error view's "Try again" and "Reload app" cover what remains.

Fixes #12918.

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Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — The PR is a focused reliability fix, adding bounded retries and timeout handling to the desktop bearer-session exchange with targeted tests. Because it changes production authentication behavior, human review is required.

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📥 Commits

Reviewing files that changed from the base of the PR and between 4f15f06 and cc43e33.

📒 Files selected for processing (2)

• apps/web/src/authBootstrap.test.ts
• apps/web/src/environments/primary/auth.ts

🚧 Files skipped from review as they are similar to previous changes (2)

• apps/web/src/authBootstrap.test.ts
• apps/web/src/environments/primary/auth.ts

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📝 Walkthrough

Walkthrough

Desktop bearer-session bootstrap now retries transient failures and times out after 15 seconds. Web session bootstrap now converts initial fetch failures into a requires-auth state with environment-specific authentication metadata.

Changes

Authentication bootstrap recovery

Layer / File(s)	Summary
Desktop token retry handling apps/desktop/src/backend/DesktopLocalEnvironmentAuth.ts, apps/desktop/src/backend/DesktopLocalEnvironmentAuth.test.ts	Transient HTTP statuses, transport failures, timeouts, and network TypeErrors are retried every 500 ms for up to 15 seconds. Tests verify recovery after two HTTP 503 responses.
Web authentication fallback apps/web/src/environments/primary/auth.ts, apps/web/src/authBootstrap.test.ts	Initial session-fetch failures now return requires-auth with desktop, loopback, or remote authentication metadata. Tests verify the returned state and error message for each context.

Priority: ⬆️ High

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix · Severity of issue fixed: High

Sequence Diagram(s)

sequenceDiagram
  participant WebBootstrap
  participant PrimaryEnvironment
  participant AuthGate
  WebBootstrap->>PrimaryEnvironment: Fetch session state
  PrimaryEnvironment-->>WebBootstrap: HTTP 500 failure
  WebBootstrap->>AuthGate: Build fallback auth descriptor
  AuthGate-->>WebBootstrap: Return requires-auth state

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🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 4 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.
Description check	⚠️ Warning	The description explains the retry behavior and its motivation, but it says the renderer fallback was dropped. The changes add fallback authentication metadata when session fetch fails. It also omits …	Correct the maintainer note to describe the renderer fallback. Add a Scope and approval section with the issue or maintainer approval details, or explain why the change qualifies as a focused fix. Update Verification to include the renderer…

✅ Passed checks (3 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Issue #12918 requires recovery from transient desktop bootstrap failures, authenticated launch to the chat view, unauthenticated launch to the pairing UI, and no RootRouteErrorView caused by `Deskto…
Out of Scope Changes check	✅ Passed	The changes address issue #12918. They add desktop bearer-session retry handling, renderer authentication fallback handling, and tests for both behaviors. The metadata distinction for desktop, local b…
Title check	✅ Passed	The title clearly summarizes both main changes: retrying transient desktop bearer-bootstrap failures and degrading when session fetch fails.

Full details: Description check

Explanation

The description explains the retry behavior and its motivation, but it says the renderer fallback was dropped. The changes add fallback authentication metadata when session fetch fails. It also omits the required scope and approval details, and does not report verification for the renderer changes.

Resolution

Correct the maintainer note to describe the renderer fallback. Add a Scope and approval section with the issue or maintainer approval details, or explain why the change qualifies as a focused fix. Update Verification to include the renderer tests and their observed results, plus any checks that were not run.

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Actionable comments posted: 1

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🤖 Prompt to fix review comments

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Inline comments:
In `@apps/web/src/environments/primary/auth.ts`:
- Around line 323-328: The fallbackAuth construction in the fetchSessionState
error path must use browser-specific metadata when window.desktopBridge is
absent: select loopback-browser or remote-reachable based on the local versus
remote web environment, with one-time-token as the bootstrap method. Preserve
desktop-managed-local with desktop-bootstrap only when the desktop bridge
exists.

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📥 Commits

Reviewing files that changed from the base of the PR and between 1de563c and 4f15f06.

📒 Files selected for processing (4)

• apps/desktop/src/backend/DesktopLocalEnvironmentAuth.test.ts
• apps/desktop/src/backend/DesktopLocalEnvironmentAuth.ts
• apps/web/src/authBootstrap.test.ts
• apps/web/src/environments/primary/auth.ts

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[juliusmarminge]

Thanks @jamesvillarrubia, this is the right fix. I merged current main (the bootstrap token now rotates, #16275) and pushed a follow-up commit. It matches retryable failures on the request error tags, and adds a test that a rejected credential is not retried. I also dropped the renderer fallback: on desktop it showed the pairing form, which asks for a token there is no way to get. With the exchange retrying, the root error view's Try again and Reload cover what's left. Details are in the description.