A shadow is a small render pipeline.

Depth becomes a transparent shadow target, two blur passes soften it, and the normal scene is restored. The target handoff stays visible so darkness, opacity, and blur are not confused with light-shadow maps.

This route preserves the source-backed contact-shadow render pipeline with deterministic local meshes. The official presentation, exact page/pixel fidelity, device/compiler coverage, context-loss stress, and whole-example fidelity remain unverified.