model: progress of long commands, reported by the solvers and the tet mesher

fieldcraft_model::progress: a host installs a Progress on the worker thread
and reads its snapshot from another; the engine names the step being solved,
the nonlinear solver its load factor, the explicit solver its time, the
fluid solver its steps, transient heat its increments and the tet mesher its
stage and pass. Without one installed every report is a no-op (#322, #357).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo

crates/mesh/src/tet/improve.rs

@@ -458,6 +458,8 @@ pub fn improve(cx: &mut TetComplex, ctx: &Context, o: &ImproveOptions) -> Result
             break;
         }
         stats.passes += 1;
+        fieldcraft_model::progress::stage("Improvement pass", Some(o.max_passes as f64), "");
+        fieldcraft_model::progress::count(stats.passes as f64);
         let before = match carried.take() {
             Some(b) => b,
             None => indicators(cx)?,

crates/mesh/src/tet/mod.rs

@@ -445,6 +445,8 @@ fn boundary_volume(points: &[[f64; 3]], tets: &[[u32; 4]], boundary: &[TaggedFac
     enclosed_volume(points, &triangles)
 }
 
+use fieldcraft_model::progress;
+
 /// Run the quality pipeline on a constrained Delaunay tetrahedralization of `surface` (see the
 /// module docs). `analytic[face]` is the exact surface of a B-rep face when known.
 pub fn quality_mesh(surface: &BoundarySurface, cdt: &TetMesh, analytic: Vec<Option<AnalyticSurface>>, o: &QualityOptions) -> Result<QualityMesh> {
@@ -486,7 +488,9 @@ pub fn quality_mesh(surface: &BoundarySurface, cdt: &TetMesh, analytic: Vec<Opti
     report.collapsed = refine::coarsen(&mut cx, &ctx, 0.6, 1.4, 0.05, 6)?;
     seed_curves(&mut cx, &ctx, &o.seeds, global)?;
     let ropt = RefineOptions { radius_edge: o.radius_edge, ..RefineOptions::default() };
-    for _ in 0..o.rounds {
+    progress::stage("Refinement round", Some(o.rounds as f64), "");
+    for round in 0..o.rounds {
+        progress::count((round + 1) as f64);
         let stats = refine::refine(&mut cx, &ctx, &ropt)?;
         let quiet = stats.interior + stats.boundary == 0;
         let stopped = stats.stopped.clone();
@@ -510,6 +514,7 @@ pub fn quality_mesh(surface: &BoundarySurface, cdt: &TetMesh, analytic: Vec<Opti
     }
     // Put the boundary vertices on the exact surfaces (the tessellation is within its chordal
     // tolerance of them).
+    progress::stage("Snapping to the geometry", None, "");
     report.unsnapped = snap_to_geometry(&mut cx, &exact, true)?;
     let c = cx.compact()?;
     let boundary: Vec<TaggedFace> = c.boundary.iter().map(|&(tet, k, face)| TaggedFace { tet, opposite: k as u8, face }).collect();