Add cached token fallback for network errors in LtiTokenRetriever

[Copilot]

The token retriever already caches JWTs in sessionStorage and falls back to cache on HTTP errors, but not on network failures (fetch exceptions). This adds the same fallback behavior for network errors.

Changes

• LtiTokenRetriever.jsx: Added cached token fallback in catch block

  } catch (error) {
    // Try to get cached JWT before failing
    const cachedJwt = loadJwt();
    if (cachedJwt) {
      handleJwt(cachedJwt, server);
      setState({ loading: false, error: null });
      return;
    }
    setState({ loading: false, error: error.message });
  }

• LtiTokenRetriever.test.jsx: Added test coverage for network error fallback scenarios and improved test isolation with sessionStorage cleanup

Behavior

Cached tokens now serve as fallback for:

• Non-200 HTTP responses (except 403) — already existed
• Network errors (fetch failures) — new

Errors still display when no cached token exists.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• example.com
  • Triggering command: node (vitest 3) (dns block)
  • Triggering command: node (vitest 2) (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

Update the token retriever to store the token in the browser and use that if the token can't be retrieved from the fetch call.

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💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[sonarqubecloud]

Quality Gate failed

Failed conditions
4.4% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud

[buckett]

This is all wrong so closing.