Transient snap store failures during `build-snaps` resolution were retried, but after the last non-404 failure the error was dropped and installation continued without the requested snap. That left the build to fail later with a misleading missing-tool error instead of surfacing the actual store failure. - **Behavior change** - Preserve the existing retry loop for snap store lookups. - Continue mapping `404` to `SnapUnavailable`. - Re-raise the final non-404 `HTTPError` once retries are exhausted so snap installation stops at the real failure point. - **Regression coverage** - Add a unit test covering repeated `500` responses from the snap store. - Assert that `install_snaps()` retries 5 times and then raises, instead of silently skipping installation. - **Effect on callers** - `build-snaps` installation now fails immediately on persistent store-side errors. - Successful resolution paths and existing base-snap channel handling remain unchanged. ```python except exceptions.HTTPError as http_error: if http_error.response.status_code == HTTPStatus.NOT_FOUND: raise errors.SnapUnavailable(...) from http_error retry_count -= 1 if retry_count == 0: raise ``` <!-- START COPILOT CODING AGENT SUFFIX --> - Fixes #1723