Validate renderer shader descriptors

docs/modernization/build-inventory.md

@@ -88,7 +88,8 @@ Known local toolchain state:
   `pp_ui_core`, `pano_cli`, and their current headless test binaries,
   including foundation event/logging/task queue coverage, PNG metadata, PPI
   header, settings document, document frame move/duration coverage, paint
-  brush/stroke coverage, UI color parsing, and layout XML parse coverage.
+  brush/stroke coverage, renderer shader descriptor coverage, UI color
+  parsing, and layout XML parse coverage.
 - `pano_cli inspect-image` reports PNG IHDR metadata as JSON and is covered by
   `pano_cli_inspect_png_metadata_smoke` with a tiny IHDR fixture.
 - `panopainter_validate_shaders` validates the current combined GLSL shader

docs/modernization/roadmap.md

@@ -364,8 +364,9 @@ adding new backends.
 
 Status: started. `pp_renderer_api` exists as a headless renderer-neutral target
 with texture descriptor, byte-size, viewport, mesh, readback bounds, command
-context, render device, shader, mesh, render target, readback, and trace
-interface validation. OpenGL classes are not yet behind these interfaces.
+context, render device, shader program descriptor, mesh, render target,
+readback, and trace interface validation. OpenGL classes are not yet behind
+these interfaces.
 
 Implementation tasks:
 
@@ -563,7 +564,7 @@ Results:
 - `pp_paint_stroke_tests` passed.
 - `pp_document_tests` passed, including frame move, duration, and history
   invariants.
-- `pp_renderer_api_tests` passed.
+- `pp_renderer_api_tests` passed, including shader descriptor validation.
 - `pp_paint_renderer_compositor_tests` passed.
 - `pp_ui_core_color_tests` passed.
 - `pp_ui_core_layout_value_tests` passed.