Investigation: #321639 (GitHubLoginFailed) is unrelated to #321956

[Copilot]

Description

Investigated whether unhandlederror-GitHubLoginFailed (#321639) is the same error addressed by #321956 and would be fixed by it. Conclusion: no — they are two distinct errors in different layers. No code change is warranted in this repository.

Findings

• This issue ([Error] [GitHub.copilot-chat] unhandlederror-GitHubLoginFailed #321639) — GitHubLoginFailedError (extends ErrorNoTelemetry) thrown by _authShowWarnings in the Copilot Chat extension: extensions/copilot/src/platform/authentication/vscode-node/copilotTokenManager.ts:136, when no GitHub session is found. Matches the reported frame xie._authShowWarnings (…/extensions/copilot/dist/extension.js).
• fix: prevent expected Copilot auth error from leaking as unhandled rejection (fixes #321950) #321956 / [Error] unhandlederror-Authentication is required to use Copilot #321950 — ProtocolError(AHP_AUTH_REQUIRED) (code -32007, message "Authentication is required to use Copilot") re-raised by a catch-less void promise.finally(...) cleanup chain in core: src/vs/platform/agentHost/common/state/agentSubscription.ts (trackSessionCreate).
• The two differ in error type, message, telemetry bucket, and originating layer. fix: prevent expected Copilot auth error from leaking as unhandled rejection (fixes #321950) #321956 modifies only agentSubscription.ts and never touches the extension's token-fetch path, so it cannot fix [Error] [GitHub.copilot-chat] unhandlederror-GitHubLoginFailed #321639.

Why no code change here

The throw site lives in extensions/copilot/, the vendored build of the Copilot Chat extension (synced from microsoft/vscode-copilot-chat). A fix for the GitHubLoginFailed unhandled-error path belongs upstream, not in this clone.

Recommendation

Keep #321639 separate from #321956; route the GitHubLoginFailed fix to microsoft/vscode-copilot-chat.