Paint a body with context rows once, into its layer, and join it

joinBody replaces the second paint of a file body with compact tree-sitter
context rows: the body is painted once into its body layer (more rows than
the grid has) and the grid's body rows are copies of the layer's first
ones; the rail is the grid's alone, from its region. Which rows are context
rows is still decided by a text build before the paint, and a body without
them reuses that text and paints straight onto the grid: every other body
has no row the grid cannot show, so it gets no layer and no copy.

Each part now paints only its own rows. The tag paints the tag rows of
every pointer sweep that crosses them (the select sweep in the tag's
colours, the look-hover affordance over it, a middle or right sweep over
both in its button's tint), which the body used to paint over the tag on
the grid alone; the body paints only body rows, and a select sweep begun on
the tag marks the body rows it crossed before the text is laid down, as it
did. Grid and layers agree, the snapshot goldens are byte-identical, and a
test checks the joined grid rows and caret against a plain paint of the
same body with the tag on top and at the bottom. The GUI goldens gain a
terminal pane scene.

1 files changed, 10 insertions, 0 deletions

diff --git a/docs/render-pipeline.md b/docs/render-pipeline.md
index 590a7e72..f63b9a0b 100644
--- a/docs/render-pipeline.md
+++ b/docs/render-pipeline.md
@@ -842,6 +842,16 @@ goldens; ssh/tty byte budgets; wire version bump breaks mixed-version attach.
 4. The macOS shell breaks at stages 7 and 8 (Layer ABI, mark_hover). Accepted,
    since the macOS build is ignored for now.
 5. Stage-0 GPU goldens gate locally only.
+6. Revisit at the first visual stage (from stage 5): the notice layer lost
+   its hover word to keep the grid's behaviour. Notice words are Look/Exec
+   targets, so bring the hover affordance back in BOTH the grid and the
+   layer then.
+7. Revisit at stage 8 (from stage 6): a body without context rows has no
+   layer (paint once, straight onto the grid). If the GUI is to read every
+   body from a layer, give every body one then and measure the copy. The
+   context-row path also still builds the body's text twice (a pre-pass
+   with body_rows 0 decides the context rows, renderBody builds it again at
+   the layer's rows); the paint is single. Measure both there.
 
 ## 15. Questions for the user