Buildpack detection failure during Node.js runtime version mismatch

Node.js Buildpack Component

When deploying applications to Scalingo, the buildpack detection process relies on the runtime version specified in the application configuration. If the requested Node.js version falls outside the currently supported matrix provided by the platform, the build phase is rejected.

While explicit runtime pinning or buildpack overrides can be used to bypass certain restrictions, the interaction between the engines field in package.json and the platform's available runtimes can lead to non-deterministic fallback behavior rather than a clear error.

• How does the platform resolve conflicts when the engines field contradicts the pinned runtime version?
• What is the deterministic behavior for buildpack selection when a version is deprecated but not yet removed from the supported matrix?