[dviejokfs]

Summary

• Detect GitHub's 422 name already exists response and surface it as a typed GitProviderError::RepositoryAlreadyExists { name } variant.
• Map the new variant to 409 Conflict with a clear detail message, so the frontend can show actionable feedback instead of a generic 500.
• Stop double-wrapping GitProviderManagerError::ProviderError — forward the typed Problem directly.
• Frontend: rewrite extractProblemDetails to (1) use the correct RFC 7807 field name type (not type_url), (2) unwrap body / error / data envelopes used by hey-api's openapi-ts client, and (3) gate detection on a proper type guard so unrelated thrown objects are not misidentified as ProblemDetails.

Files

• crates/temps-git/src/services/git_provider.rs — new error variant
• crates/temps-git/src/services/github_provider.rs — parse 422 body, detect name field "already exists"
• crates/temps-git/src/handlers/base.rs — map variant to 409, drop redundant wrapping
• crates/temps-projects/src/handlers/handlers.rs — propagate typed Problem instead of converting to 500
• web/src/utils/errorHandling.ts — fix RFC 7807 field name and envelope unwrapping

Test plan

• Create a repository through the project flow with a name that already exists on the linked GitHub account → expect a 409 with a "Repository Already Exists" toast/banner instead of a 500.
• Create a repository with a fresh name → expect success unchanged.
• Hit any other ProblemDetails-returning endpoint and confirm the frontend still extracts title / detail correctly through both the bare and body-nested shapes.