engine: a mesh made before its seeds changed is out of date; a remesh names a type change

The setup checklist marks the mesh Outdated (a warm ⚠ in the browser, with
what changed and where to remesh) when seeds, partitions or datum planes
changed after the last mesher ran, and model.check warns (#342). Replacing
a mesh asks with the element type change it makes, such as tet10 → tet4 (#343).

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

crates/engine/src/cmd/model.rs

@@ -55,7 +55,10 @@ fn units(s: &mut Session, p: &Value) -> Result<Value> {
 }
 
 fn check(s: &mut Session, _: &Value) -> Result<Value> {
-    let diagnostics = s.model.check();
+    let mut diagnostics = s.model.check();
+    if let Some(why) = s.mesh_outdated() {
+        diagnostics.push(fieldcraft_model::Diagnostic { severity: Severity::Warning, subject: "mesh".into(), message: why });
+    }
     let errors = diagnostics.iter().filter(|d| d.severity == Severity::Error).count();
     let first_error = diagnostics.iter().find(|d| d.severity == Severity::Error).map(ToString::to_string);
     let progress = crate::progress::to_json(&s.progress_given(first_error));

crates/engine/src/cmd/replace.rs

@@ -102,6 +102,28 @@ fn design_bodies(s: &Session) -> Result<Vec<String>> {
     Ok(design.bodies.iter().map(|b| b.name.clone()).collect())
 }
 
+/// Tetrahedra and hexahedra of either order: the kinds an order change swaps.
+fn family(k: ElementKind) -> Option<u8> {
+    match k {
+        ElementKind::Tet4 | ElementKind::Tet10 => Some(0),
+        ElementKind::Hex8 | ElementKind::Hex20 => Some(1),
+        _ => None,
+    }
+}
+
+/// The solid element type `command` makes with `params`, when it makes one type.
+fn made_kind(command: &str, params: &Value) -> Option<ElementKind> {
+    match command {
+        "mesh.tet.generate" => {
+            Some(if params.get("order").and_then(Value::as_str) == Some("quadratic") { ElementKind::Tet10 } else { ElementKind::Tet4 })
+        }
+        "mesh.hex.generate" | "mesh.hex.sweep" | "mesh.hex.mapped" | "mesh.hex.blocks" => {
+            Some(if params.get("order").and_then(Value::as_i64) == Some(2) { ElementKind::Hex20 } else { ElementKind::Hex8 })
+        }
+        _ => None,
+    }
+}
+
 /// What running a meshing command would replace, for a confirmation before it runs.
 #[derive(Debug, Clone, PartialEq)]
 pub struct Replacement {
@@ -141,6 +163,14 @@ pub fn replacement(s: &Session, command: &str, params: &Value) -> Option<Replace
         }
     };
     let mut warnings = Vec::new();
+    // The element type changing (tet10 → tet4 when the order is left out) is easy to miss.
+    if let Some(new) = made_kind(command, params) {
+        let old: BTreeSet<ElementKind> = removed.elements.iter().filter_map(|l| s.model.element(*l)).map(|e| e.kind).collect();
+        let changed: Vec<&str> = old.iter().filter(|k| **k != new && family(**k) == family(new)).map(|k| k.name()).collect();
+        if !changed.is_empty() {
+            warnings.push(format!("The element type changes: {} → {}.", changed.join(", "), new.name()));
+        }
+    }
     let stale = s.model.sets_using(&removed);
     if !stale.is_empty() {
         warnings.push(format!("Sets that list its nodes or elements by label ({}) will name labels of the old mesh.", stale.join(", ")));
@@ -194,6 +224,17 @@ mod tests {
         (dir, s)
     }
 
+    /// Remeshing without the order would turn tet10 into tet4: the question says so (#343).
+    #[test]
+    fn an_element_type_change_is_named() {
+        let (_dir, mut s) = two_boxes();
+        s.execute("mesh.tet.generate", &json!({"body": "Box", "size": 5, "order": "quadratic"})).unwrap();
+        let r = replacement(&s, "mesh.tet.generate", &json!({"body": "Box", "size": 4})).unwrap();
+        assert!(r.warnings.iter().any(|w| w == "The element type changes: tet10 → tet4."), "{r:?}");
+        let same = replacement(&s, "mesh.tet.generate", &json!({"body": "Box", "order": "quadratic"})).unwrap();
+        assert!(same.warnings.iter().all(|w| !w.contains("element type")), "{same:?}");
+    }
+
     /// A body's elements, by label.
     fn elements_of(s: &Session, body: &str) -> BTreeMap<u32, Element> {
         s.model.body_elements(body).into_iter().filter_map(|l| Some((l, s.model.element(l)?.clone()))).collect()

crates/engine/src/progress.rs

@@ -97,6 +97,9 @@ pub enum Status {
     Blocked,
     /// Not done, and not needed for this model.
     Optional,
+    /// Done, but what it was made from changed since (`detail` says what): a mesh made before
+    /// its seeds or partitions changed.
+    Outdated,
 }
 
 /// One row of the checklist.
@@ -148,7 +151,10 @@ impl Session {
                     _ if stage == Stage::Solve => first_error.clone(),
                     _ => None,
                 };
-                let (status, detail) = if done {
+                let outdated = if done && stage == Stage::Mesh { self.mesh_outdated() } else { None };
+                let (status, detail) = if let Some(why) = outdated {
+                    (Status::Outdated, Some(why))
+                } else if done {
                     (Status::Done, None)
                 } else if optional {
                     (Status::Optional, None)
@@ -167,6 +173,35 @@ impl Session {
     }
 }
 
+impl Session {
+    /// Why the mesh no longer matches what steers it: seeds, partitions or the datums they cut
+    /// by changed after the last mesher ran (the journal says what ran when). `None` when it
+    /// matches, or no mesher made it.
+    pub fn mesh_outdated(&self) -> Option<String> {
+        let mesher = self.journal.iter().rposition(|(c, _)| crate::MESHERS.iter().any(|(m, _)| m == c))?;
+        let (command, _) = self.journal.get(mesher)?;
+        let mut changed = Vec::new();
+        for (c, _) in self.journal.get(mesher + 1..).unwrap_or_default() {
+            let what = match c.as_str() {
+                "mesh.seed.edge" | "mesh.seed.clear" => "Seeds",
+                "geometry.partition" | "geometry.partition.delete" => "Partitions",
+                "geometry.datum.edit" => "Datum planes",
+                _ => continue,
+            };
+            if !changed.contains(&what) {
+                changed.push(what);
+            }
+        }
+        let place = crate::catalogue::entry_of(command).map_or_else(|| command.clone(), |e| format!("{} › {}", e.tab.label(), e.label));
+        let what = match changed.as_slice() {
+            [] => return None,
+            [one] => one.to_string(),
+            [first @ .., last] => format!("{} and {}", first.join(", "), last.to_lowercase()),
+        };
+        Some(format!("{what} changed since this mesh was made — {place} to remesh"))
+    }
+}
+
 /// The checklist as JSON, with the next stage's command first for agents:
 /// `{"next": {"stage", "command"} | null, "stages": [...]}`.
 pub fn to_json(stages: &[StageState]) -> Value {
@@ -247,6 +282,21 @@ mod tests {
         assert_eq!(status(&s, Stage::Solve), Next, "{:?}", s.progress());
     }
 
+    /// A seed added after meshing marks the mesh out of date, until a remesh (#342).
+    #[test]
+    fn a_seed_after_the_mesh_marks_it_outdated() {
+        let mut s = Session::default();
+        s.execute("file.sample", &json!({"name": "bracket-hex"})).unwrap();
+        assert_eq!(status(&s, Stage::Mesh), Done);
+        let edge = json!({"body": "Bracket (1) (1)' (1)", "edge": "F17:face:5|F2:side:l1"});
+        s.execute("mesh.seed.edge", &json!({"edges": [edge], "count": 6})).unwrap();
+        assert_eq!(status(&s, Stage::Mesh), Outdated);
+        let why = s.mesh_outdated().unwrap();
+        assert!(why.starts_with("Seeds changed since this mesh was made — Mesh › "), "{why}");
+        let v = s.execute("model.check", &json!({})).unwrap();
+        assert!(v.to_string().contains("Seeds changed since this mesh was made"), "{v}");
+    }
+
     #[test]
     fn model_check_returns_the_checklist() {
         let mut s = Session::default();

crates/ui-egui/src/browser.rs

@@ -65,7 +65,7 @@ fn node_stages(node: &str) -> &'static [Stage] {
 fn stage_tip(s: &StageState) -> Option<String> {
     match s.status {
         Status::Next => Some(format!("Next: {} — {}", s.label, s.place)),
-        Status::Blocked => Some(s.detail.clone().unwrap_or_else(|| s.place.clone())),
+        Status::Blocked | Status::Outdated => Some(s.detail.clone().unwrap_or_else(|| s.place.clone())),
         Status::Todo => Some(format!("{} still to do — {}", s.label, s.place)),
         Status::Done | Status::Optional => None,
     }
@@ -75,8 +75,9 @@ fn stage_tip(s: &StageState) -> Option<String> {
 /// else done; `None` for nodes that are no setup stage.
 fn node_state(stages: &[StageState], node: &str) -> Option<(Status, String)> {
     let own: Vec<&StageState> = stages.iter().filter(|s| node_stages(node).contains(&s.stage)).collect();
-    let status =
+    let status = [Status::Outdated, Status::Next, Status::Blocked, Status::Todo, Status::Done, Status::Optional]
-        [Status::Next, Status::Blocked, Status::Todo, Status::Done, Status::Optional].into_iter().find(|st| own.iter().any(|s| s.status == *st))?;
+        .into_iter()
+        .find(|st| own.iter().any(|s| s.status == *st))?;
     let tip: Vec<String> = own.iter().filter_map(|s| stage_tip(s)).collect();
     let tip = if tip.is_empty() { "Done".to_string() } else { tip.join("\n") };
     Some((status, tip))
@@ -606,7 +607,7 @@ fn item_row(app: &mut ModelApp, ui: &mut egui::Ui, id: egui::Id, mut row: Row, t
     }
 }
 
-/// ✓ done (success), → next (accent), ⚠ blocked (muted); nothing for the rest.
+/// ✓ done (success), → next (accent), ⚠ blocked (muted), ⚠ out of date (warm); nothing for the rest.
 fn paint_mark(p: &egui::Painter, r: Rect, status: Status, t: &Tokens) {
     let at = |x: f32, y: f32| Pos2::new(r.left() + x * r.width(), r.top() + y * r.height());
     match status {
@@ -627,6 +628,12 @@ fn paint_mark(p: &egui::Painter, r: Rect, status: Status, t: &Tokens) {
             p.line_segment([at(0.5, 0.35), at(0.5, 0.65)], s);
             p.circle_filled(at(0.5, 0.84), 0.7, t.text_dim);
         }
+        Status::Outdated => {
+            let s = Stroke::new(1.3, t.warm);
+            p.add(egui::Shape::closed_line(vec![at(0.5, 0.0), at(1.05, 1.0), at(-0.05, 1.0)], s));
+            p.line_segment([at(0.5, 0.35), at(0.5, 0.65)], s);
+            p.circle_filled(at(0.5, 0.84), 0.8, t.warm);
+        }
         Status::Todo | Status::Optional => {}
     }
 }