Forms: a one-line note per choice; the hex Method says what each needs

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

crates/engine/src/cmd/forms.rs

@@ -999,7 +999,11 @@ pub const HEX_GENERATE: &[Field] = &[
         "Method",
         &[("auto", "Automatic"), ("swept", "Any sweep"), ("extrude", "Extrude"), ("sweep", "Sweep"), ("revolve", "Revolve"), ("mapped", "Mapped")],
     )
-    .help("How to build the hexes: automatic, or a sweep, extrusion, revolution or mapped mesh.")
+    .help(
+        "How to build the hexes. Automatic tries, in order, an extrusion, a sweep, a revolution and a mapped block, and \
+         uses the first that fits; Any sweep tries the first three.",
+    )
+    .notes(HEX_METHOD_NOTES)
     .def("\"auto\""),
     TOLERANCE,
     WELD,
@@ -1007,6 +1011,16 @@ pub const HEX_GENERATE: &[Field] = &[
     FEATURE_ANGLE,
 ];
 
+/// What each structured hex method needs of the body, one line each.
+const HEX_METHOD_NOTES: &[(&str, &str)] = &[
+    ("auto", "Automatic: the first of Extrude, Sweep, Revolve and Mapped that fits the body."),
+    ("swept", "Any sweep: the first of Extrude, Sweep and Revolve that fits the body."),
+    ("extrude", "Extrude: the body must be one cross-section carried along a straight direction (levels allowed)."),
+    ("sweep", "Sweep: a source face carried to a target face through four-sided linking faces."),
+    ("revolve", "Revolve: the body must be one cross-section turned around an axis."),
+    ("mapped", "Mapped: the body must have six sides, each with four edges (curved faces allowed)."),
+];
+
 pub const HEX_SWEEP: &[Field] = &[
     BODY,
     SURFACE,
@@ -1014,6 +1028,7 @@ pub const HEX_SWEEP: &[Field] = &[
     HEX_ORDER,
     choice("method", "Method", &[("swept", "Any sweep"), ("extrude", "Extrude"), ("sweep", "Sweep"), ("revolve", "Revolve")])
         .help("How to sweep: any sweep, extrusion, sweep along a path or revolution.")
+        .notes(HEX_METHOD_NOTES)
         .def("\"swept\""),
     TOLERANCE,
     WELD,
@@ -1039,8 +1054,13 @@ pub const CELLS: &[Field] = &[
     json("methods", "Methods")
         .help("The meshing method per cell, as JSON.")
         .hint(r#"{"cell": "auto | hex | swept | extrude | sweep | revolve | mapped | tet"}"#),
-    choice("default", "Other cells", &[("auto", "Auto (hex, else tet)"), ("hex", "Hex"), ("swept", "Swept"), ("mapped", "Mapped"), ("tet", "Tet")])
-        .help("The method for cells not listed in Methods.")
+    choice(
+        "default",
+        "Other cells",
+        &[("auto", "Auto (hex, else tet)"), ("hex", "Hex"), ("swept", "Swept"), ("mapped", "Mapped"), ("tet", "Tet"), ("blocks", "All hex (conforming blocks)")],
+    )
+    .help("The method for cells not listed in Methods. All hex meshes every cell as a mapped block, with the division counts of all cells assigned together so shared faces match (mesh.hex.blocks).")
+    .notes(&[("blocks", "All hex: every cell must have six sides, each with four edges; leave Methods empty.")])
         .def("\"auto\""),
     references("bodies", "Cells", C::Body).help("The cells (bodies) to mesh; every body of the design when empty.").hint("every body of the design"),
     HEX_SIZE,

crates/engine/src/schema.rs

@@ -36,6 +36,9 @@ pub struct Field {
     /// What the field means, in a sentence or two, with a typical value: the form's tooltip and
     /// the JSON Schema description. The unit is added from the field's dimension ([`Field::help_text`]).
     pub help: &'static str,
+    /// For a [`Kind::Choice`]: a one-line note per option value (what it needs), shown under the
+    /// field for the option chosen.
+    pub notes: &'static [(&'static str, &'static str)],
 }
 
 /// What a field holds.
@@ -306,7 +309,7 @@ impl Dim {
 // ---- Building fields (const, so schemas are static tables) ----
 
 const fn field(key: &'static str, label: &'static str, kind: Kind) -> Field {
-    Field { key, label, kind, required: false, default: None, hint: "", help: "" }
+    Field { key, label, kind, required: false, default: None, hint: "", help: "", notes: &[] }
 }
 
 impl Field {
@@ -327,6 +330,16 @@ impl Field {
         Field { help, ..self }
     }
 
+    /// A one-line note per option value ([`Field::notes`]).
+    pub const fn notes(self, notes: &'static [(&'static str, &'static str)]) -> Field {
+        Field { notes, ..self }
+    }
+    /// The note for this option value (the default when `None`).
+    pub fn note(&self, value: Option<&str>) -> Option<&'static str> {
+        let value = value.or_else(|| self.default.map(|d| d.trim_matches('"')))?;
+        self.notes.iter().find(|(v, _)| *v == value).map(|(_, n)| *n)
+    }
+
     /// Its physical dimension, for a number or a vector of numbers.
     pub fn dim(&self) -> Option<Dim> {
         match self.kind {