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.

docs/configurations.md

@@ -36,8 +36,66 @@ face appearances keep their existing priority. Physical material changes affect
 
 Style columns target body names. Assignments remain stored when a row suppresses the feature
 that produces that body, and become visible when it returns. Component and face appearance
-columns and conditional configuration rules are not yet supported.
+columns are not yet supported.
 
-Designs saved with these columns use file format 7. Older designs upgrade on opening without
+Activation evaluates all row parameter expressions together, so column order does not create
+temporary dependency cycles. Preview and activation reject new or changed geometry errors
+without changing the design. An identical existing error remains visible. A saved row cannot
+recreate a deleted parameter: remove its configuration references before deleting it. Deleting
+a feature removes its input and suppression columns and any rules referring to that feature.
+
+## Ordered rules and preview
+
+Open **Add or edit rule** below the table. Give the rule a name, choose when it applies, then
+choose a driven parameter, driven suppression, numeric range, or allowed values. Numeric
+fields accept ordinary design expressions and explicit units. **Edit**, the arrow buttons,
+the enable checkbox, and **Delete** update existing rules. Choose **All**, **Any**, or **Not**
+to build compound conditions with nested controls, **Add condition**, and **Remove condition**.
+
+**Preview Row** rebuilds a scratch design and shows effective expressions and matched or
+skipped rules. Driven and restricted values identify the rule responsible. It leaves the
+current geometry, active row, and undo history unchanged. **Apply** or **Activate** publishes
+the validated variant as one undoable action.
+
+Rules execute in list order. Each condition sees earlier drives; restrictions from matched
+rules all apply to the final values. A range includes its endpoints. Allowed values compare
+numeric values with matching dimensions, so `1 cm` equals `10 mm`. An angle never equals a
+length. Bare expressions use the target parameter's unit, or the document's unit for feature
+length inputs. Equality uses a relative/absolute tolerance of `1e-9` in internal units.
+The rule editor's **Length units** selector sets the meaning of bare feature-length
+expressions; explicit units override it. Rules capture this unit context when authored. Changing document units
+preserves mixed expressions such as `width + 1` without treating `width * 2` as a length
+multiplier. Bare saved feature length cells and rule thresholds gain the previous explicit
+unit; explicit units and nonliteral source expressions retain their text. A matching active
+row rederives its driven values when units change. User parameters retain their own units.
+
+Rules recompute on configured edits, **Apply**, and **Preview Row**. Ordinary parameter
+edits can leave the configuration unmatched and do not continuously enforce restrictions.
+Cross-unit drives store effective numeric lengths; their saved source expressions reevaluate
+on the next Apply or Preview rather than following later ordinary parameter edits live.
+Saved source cells are preserved: disabling a drive restores the row's original choice.
+
+```json
+{"command":"config.rule","params":{"rule":{"id":"depth-rule","name":"Large parts use deeper stock","condition":{"type":"parameter","parameter":"width","operator":"ge","expression":"80 mm"},"effect":{"type":"drive_parameter","parameter":"depth","expression":"width / 2"}}}}
+{"command":"config.rule","params":{"rule":{"id":"width-range","name":"Stock width","condition":{"type":"always"},"effect":{"type":"parameter_range","parameter":"width","minimum":"10 mm","maximum":"100 mm"}}}}
+{"command":"config.preview","params":{"row":"Aluminum blue"}}
+{"command":"config.rule","params":{"id":"width-range","index":0}}
+```
+
+Configure the `depth` column before adding this example drive. Conditions may reference any
+existing design parameter; effect targets must be configured columns. `config.rules` lists
+rules. `config.rule` replaces a rule with the same ID, deletes with `id` and `delete: true`,
+or moves it to a zero-based `index`. Editing a rule validates every saved row before committing;
+editing a row validates that row. Invalid geometry, dependency cycles, incompatible units,
+or restrictions leave the previous document intact and explain the failure. Delete rules
+before removing the last row. Parameter renames update rule targets and expressions; rule
+references prevent parameter deletion until removed.
+
+Tables support at most 128 rules; conditions allow eight levels and 64 nodes, and allowed
+value lists support up to 128 expressions. These bounds are checked before saved rules are
+decoded. Driven appearance/material rules and repeated fixed-point evaluation are outside
+the current rule scope.
+
+Designs saved with rules use file format 8. Older designs upgrade on opening without
 changing their existing configuration values. Older SolveCraft versions must be updated to
 open newly saved designs.