Run wire arena regressions in CI and shorten cache documentation

src/scene/pipeline/gpu_budget.rs

@@ -8,13 +8,8 @@ fn device_ceiling(device: &wgpu::Device) -> usize {
     (usize::try_from(device.limits().max_buffer_size).unwrap_or(usize::MAX) / 10) * 9
 }
 
-/// The wire arena keeps one persistent instance buffer for the whole resident
-/// set and patches it in place. Capping that at the per-chunk budget pushes any
-/// drawing past ~524 k instances onto the batched fallback, which re-uploads
-/// everything on every edit — 200 ms a click on a drawing with 821 k. A single
-/// long-lived buffer can afford more than a transient chunk, and 128 MiB is
-/// still four times smaller than the 505 MiB allocation that crashed a 2 GB
-/// card in the first place.
+/// Persistent arenas need a larger cap than transient chunks to keep large
+/// drawings on the incremental upload path.
 const ARENA_CAP_BYTES: usize = 128 * 1024 * 1024;
 
 /// `OCS_GPU_CHUNK_MIB`, when set. Overrides both caps so a test can force

src/scene/pipeline/mod.rs

@@ -2419,15 +2419,7 @@ impl Pipeline {
             Some(&mut self.block_geometry),
         );
 
-        // Index handle → wire slots once, here, so the per-hover selection
-        // overlay can gather just the highlighted wires instead of scanning +
-        // string-parsing the whole set every time the hovered entity changes.
-        //
-        // Parsing 198 k names is the bulk of this and each one is independent,
-        // so it runs across cores; only the map insertion stays serial, and
-        // that is cheap once the parse is done. Emission order is preserved --
-        // `par_iter().enumerate()` collects in index order -- which the slot
-        // lists rely on.
+        // Parse handles in parallel, preserving wire order for hover slot lists.
         let t_index = crate::perf::enabled().then(iced::time::Instant::now);
         let parsed: Vec<(u64, u32)> = {
             use crate::par::prelude::*;