feat: preserve modeling intent across sketches, assemblies, and fabrication

Persist typed sketch dimensions and bounded ordered configuration rules in format 8. Use exact occurrence paths and source identity for editing, movement, appearance, and mass. Preserve sheet material regions through cutting, folding, and exact DXF export; retain nested cavities and material islands.

Validation: cargo xtask ci passed, including 368 engine tests, 178 UI tests, 68 UI scenarios, 136 kernel tests, and the 10-crate wasm check. Actual preview workflows and legacy format-7 origin-corner reopening were inspected.

crates/doc/src/params.rs

@@ -502,6 +502,53 @@ impl Document {
         Ok(())
     }
 
+    /// Change existing expressions against their final dependency graph, independent of
+    /// column order. Unlike `change_param`, this never creates a missing parameter.
+    pub fn change_params_atomic(&mut self, changes: &[(String, String)]) -> Result<()> {
+        if changes.len() > crate::config::MAX_COLUMNS {
+            return Err(DocError::Invalid("too many parameter changes".into()));
+        }
+        let mut names = BTreeSet::new();
+        let mut changed = BTreeSet::new();
+        let (_, before_errors) = self.param_values();
+        let mut next = self.clone();
+        for (name, expression) in changes {
+            if !names.insert(name.clone()) {
+                return Err(DocError::Invalid(format!("duplicate parameter `{name}`")));
+            }
+            if expression.len() > 4096 || expression.trim().is_empty() {
+                return Err(DocError::Expr("expression is empty or too long".into()));
+            }
+            if let Some(p) = next.params.iter_mut().find(|p| p.name == *name) {
+                if p.expr != expression.trim() {
+                    changed.insert(name.clone());
+                }
+                p.expr = expression.trim().to_string();
+                continue;
+            }
+            let hit = next.features.iter().enumerate().find_map(|(i, f)| f.param_names.iter().position(|n| n == name).map(|k| (i, k)));
+            let Some((i, k)) = hit else { return Err(DocError::Unknown(format!("parameter `{name}`"))) };
+            let kind = next.features.get(i).and_then(|f| f.kind.inputs().get(k).map(|x| x.2)).unwrap_or(Kind::Unitless);
+            let normalized = next.with_design_unit(expression, kind);
+            let Some(feature) = next.features.get_mut(i) else { return Err(DocError::Unknown(format!("parameter `{name}`"))) };
+            let Some((_, target, _)) = feature.kind.inputs_mut().into_iter().nth(k) else {
+                return Err(DocError::Unknown(format!("parameter `{name}`")));
+            };
+            if *target != normalized {
+                changed.insert(name.clone());
+            }
+            *target = normalized;
+        }
+        let (_, errors) = next.param_values();
+        for (name, error) in errors {
+            if changed.contains(&name) || !before_errors.contains_key(&name) {
+                return Err(DocError::Expr(format!("parameter `{name}`: {error}")));
+            }
+        }
+        *self = next;
+        Ok(())
+    }
+
     /// The parameters table (user, sketch dimensions, feature inputs).
     pub fn param_rows(&self) -> Vec<ParamRow> {
         let (vals, errs) = self.param_values();
@@ -639,6 +686,8 @@ pub enum ParamUser {
     Feature { feature: u64, name: String, input: String },
     /// A sketch dimension (`constraint` is its id).
     Dimension { feature: u64, name: String, constraint: String },
+    /// A configured column or an expression saved in a configuration row.
+    Configuration { row: Option<String>, column: String },
 }
 
 impl ParamUser {
@@ -647,6 +696,10 @@ impl ParamUser {
             ParamUser::Parameter { name } => format!("parameter {name}"),
             ParamUser::Feature { name, input, .. } => format!("{name} ({input})"),
             ParamUser::Dimension { name, constraint, .. } => format!("{name} dimension {constraint}"),
+            ParamUser::Configuration { row, column } => match row {
+                Some(row) => format!("configuration `{row}` ({column})"),
+                None => format!("configuration column {column}"),
+            },
         }
     }
 }
@@ -716,6 +769,24 @@ impl Document {
     /// expressions refer to it, and the sketch dimensions it drives.
     pub fn param_users(&self, name: &str) -> Vec<ParamUser> {
         let mut out = Vec::new();
+        for rule in &self.configs.rules {
+            if rule.parameter_references().iter().any(|reference| reference == name) {
+                out.push(ParamUser::Configuration { row: None, column: format!("rule `{}`", rule.name) });
+            }
+        }
+        for (index, column) in self.configs.columns.iter().enumerate() {
+            if let crate::config::Column::Param(target) = column {
+                let key = self.config_key(column);
+                if target == name {
+                    out.push(ParamUser::Configuration { row: None, column: key.clone() });
+                }
+                for row in &self.configs.rows {
+                    if row.cells.get(index).is_some_and(|value| expr::references(value).iter().any(|reference| reference == name)) {
+                        out.push(ParamUser::Configuration { row: Some(row.name.clone()), column: key.clone() });
+                    }
+                }
+            }
+        }
         for p in &self.params {
             if p.name != name && expr::references(&p.expr).iter().any(|r| r == name) {
                 out.push(ParamUser::Parameter { name: p.name.clone() });
@@ -828,6 +899,9 @@ impl Document {
             }
         }
         // Configuration cells refer to parameters too.
+        for rule in &mut self.configs.rules {
+            rule.rename_parameter(old, new);
+        }
         for r in &mut self.configs.rows {
             for (column, cell) in self.configs.columns.iter().zip(&mut r.cells) {
                 if matches!(column, crate::config::Column::Param(_)) {