docs: the traced image is unlit

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

 CLAUDE.md | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/CLAUDE.md b/CLAUDE.md
index c0829cc..faa5af2 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -1614,17 +1614,22 @@ upload at the same corners (`set_rt_scene_with_image`, a `cce_ui::vk::
 RtImage`), and cce-ui adds the quad to the traced scene as two triangles
 under a textured material — so both tiers meet it as any triangle, and a
 scene that is an image ALONE is not an empty one, which the tracer used to
-skip. Traced, the image is a SURFACE: its colour is the albedo, lit by the
-sky and shadowed by the geometry as the geometry is, where the raster pass
-draws it unlit; and where it is clear a ray goes through, by chance in
-proportion to the alpha. The traced scene's key is the geometry's version,
+skip. Traced, the image is UNLIT, as the raster pass draws it: a ray that
+lands on it takes the image's colour as it is and the path ends there, so
+the two views show the same picture — and to the rest of the scene the
+image is a light of its own colour, which is what a bounce off the
+geometry finds there. (For its first hour it was a lit surface, albedo
+under the sky, and a white page traced grey; the user's call.) Where it is
+clear a ray goes through, by chance in proportion to the alpha. The traced scene's key is the geometry's version,
 the image's (`State::page_version`, moved by every recomposition) and the
 world unit, which sizes the image. The thumbnail has no 2D pass to share
 an upload with and hands over the pixels (`RtImagePixels`); an image alone
 is taken square on and fitted edge to edge (`thumbnail::view_of`), since
 from the diagonal a picture is a slanted sliver of itself, and one with
-geometry is inside the diagonal view's bounds. The denoiser softens fine
-text on the image until the samples have settled.
+geometry is inside the diagonal view's bounds. The denoiser leaves the
+image alone: its pixels are marked as the sky's are, since a colour that
+is the image's own has no noise to take out and smoothing took its fine
+print first.
 
 **The display flag is exclusive within its CONTEXT**
 (`set_child_geometry_visible`): the page nodes and the geometry nodes each