2D shadows and normal maps

ShadowCaster2D casts: its outline (a shape path; a sprite renderer's bounds, where Unity's editor takes the sprite's own outline; or, as Unity falls back, its renderer's bounds or a unit square, stored as the path) reaches the renderer each frame with its target sorting layers and casting option (castsShadows and selfShadows map onto it as Unity's do).
The 2D lit shading dims a light by its shadow intensity where a caster's outline crosses the segment from the light to the pixel; a renderer's own caster shadows it only with self shadows. Shadows are hard-edged.
Normal maps: a light with normal map quality on is placed its normal map distance in front of the sprite's plane and scaled by saturate(N · L), as URP's normals lighting does; N comes from the sprite's _NormalMap secondary texture or its material's _NormalMap (flat facing the camera without one).
Sprites carry secondary textures (SecondarySpriteTexture, Sprite.Create with them, GetSecondaryTextures), imported from a texture's sprite settings.
The lights_2d scenario grows: light shadow settings, a caster's defaults, square path and casting options, secondary textures, and in its Unity scene a self-shadowing caster, a light with normal maps on and a sprite whose texture brings its normal map. 41 scenarios pass in both runs.
GPU tests cover shadowed and unshadowed pixels, self shadows and flat-normal falloff; an MCP e2e test covers a caster darkening the sprite behind it.
Not yet: soft shadows, sprite outlines as shadow shapes, Sprite (cookie) lights, volumetric light and shadows.
Next: agent avoidance and off-mesh links, or Sprite (cookie) lights and soft shadows.