Fill triangles (DIMTFILL backgrounds, MLEADER masks, hatches) carry the
entity's draw-order rank, but SDF glyph quads were pushed at neutral 0.0
— any entity in the front half of the draw order had its own background
fill painted over its text. gather_text_verts now adds the host wire's
wire_draw_depth to each glyph: a text background lands at the same
biased depth (glyphs draw after fills and win the LessEqual test), and
text respects draw order against other entities' fills too.
The #403 glyph-reuse fast path gains a rank-stability gate: adding or
removing an entity shifts every sibling's bias (the rank denominator
changes), so reuse is only safe across all-Modified edits.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>