Design tab: translatable offer, one vocabulary, reports in the status line

- Offer table: user-facing strings carry the L() marker so xgettext
  extracts them; DesignOffer.hpp, DesignSketchTool.cpp and
  SketchInlineEditor.cpp are listed in localization/i18n/list.txt.
- Offer: model-mode Constrain sits in the same row as the sketch one;
  Interference is wired; Rib shows its R key; a verb that accepts the
  selection but is blocked by the document stays greyed with its reason
  instead of vanishing from the submenu; one refusal wording per verb.
- Extrude infers Join when the profile touches a solid (new
  CadDocument::body_touching_sketch) and on face push/pull; New body in
  free space. Revolve/Sweep/Loft/Boolean use the same result words.
- Interference and volume/area reports go to the status line in mm3/mm2
  instead of modal dialogs; Delete Body no longer asks (it is undoable).
- New feature names match the card header ("Extrude 3"), translated;
  "Coordinate system", "Angle (°)", center/color spelling, translated
  face and length readouts, slot hints say width.
- CAD gizmos in Prepare are selectable only with the CAD feature on; the
  sketch auto-close setting is stored per design.
- Docs: confirm/cancel rules, enabling the feature and MCP in
  design_tab.md; drift-only right-click in interaction-model.md; the
  portability note rewritten to describe the integration as it is.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QK4VgguuCAk2hZLWgcjJb9

docs/CAD/design_tab.md

@@ -14,10 +14,15 @@ already ships for STEP import.
 
 ## Getting started
 
+The Design tab is experimental. It exists only in builds with `SLIC3R_CAD` on, and appears
+after **Preferences → CAD feature (experimental)** is ticked and the app restarted. Switched off,
+Prepare and every project behave exactly as without it; a project that carries a design keeps
+its recipe untouched.
+
 1. Open the **Design** tab.
 2. Click a face or a reference plane in the viewport, then press `Shift+S` (Sketch). The offer
    opens with the sketch tools on it.
-3. Draw a closed profile, then press **✓ Confirm** in the floating action bar.
+3. Draw a closed profile, then press **✓ Confirm** in the floating action bar (or `Enter`).
 4. With the sketch selected, press `Shift+E` (Extrude).
 5. Press **Commit to Plate** to hand the solid to Prepare.
 
@@ -59,7 +64,8 @@ sketch tools — the app hands you the tools directly.
 Repeat, Transform, Reference, Modify.
 
 - A family with at least one applicable verb shows it. Several applicable verbs collapse
-  into a submenu under the family name.
+  into a submenu under the family name. A verb that is about the selection but blocked by the
+  document (no body yet, no second sketch) stays in that submenu, greyed, with its reason.
 - A family with nothing applicable is **shown greyed in place, with the reason** — e.g.
   *"Create — Click a face or a reference plane in the viewport, then a sketch tool"*. It is
   not hidden. A control that cannot be used still says what it is and what you would have to
@@ -72,6 +78,22 @@ Redo, Variables, Section view, Origin planes, World axes. They live in the toolb
 
 ---
 
+## Confirm and cancel
+
+One rule everywhere, in the feature cards and in the sketch alike:
+
+- `Enter` does what **✓** does; `Esc` does what **✗** does. Neither is ever the only way.
+- `Esc` steps back exactly one level — a value field, then the gesture in progress, then the
+  armed tool, then the selection. It never deletes, discards a sketch or rolls back a feature.
+- A click on empty space clears the selection. It never applies anything: a pending fillet,
+  offset, move or array waits for `Enter` or **✓**.
+- Right-click on a tool with something pending drops that gesture; with nothing pending it
+  opens the offer, like anywhere else.
+- Switching to another tool applies a pending operation that is complete and valid, then arms
+  the new tool.
+- A value typed into a field that the geometry cannot take (a zero-length side, an arc of more
+  than 360°) is refused in place: the field stays open and says why.
+
 ## Keyboard
 
 Single letters drive sketch tools **while a sketch is open**; Shift+letter drives feature
@@ -100,8 +122,10 @@ selected by the mode, not by whether a sketch session is running.
 | `H` | Chamfer — pick two lines, set the distance |
 | `K` | Constrain — finish the live sketch and enter constrain |
 | `Q` | Construction toggle — draw the next entity as construction geometry |
-| `Del` | Delete the selected sketch entity |
-| `Esc` | Cancel the live tool |
+| `Del` | Delete the selected sketch entities (nothing selected: nothing happens) |
+| `Enter` | Apply what is pending; otherwise end the chain; otherwise drop the tool |
+| `Esc` | Undo one level: close the field, drop the gesture, drop the tool, clear the selection |
+| `Ctrl+Z` / `Ctrl+Y` | Undo / redo the last sketch edit |
 
 ### Feature (when no sketch is open)
 
@@ -151,7 +175,9 @@ kept. With no section on, `F` is Place on Face — lay the picked face flat on t
 ## Sketching
 
 A sketch is a closed (or open) 2D profile on a plane or on a flat face of an existing body.
-Press `Shift+S`, click the face or plane you want to sketch on, and draw. The toolbar and
+Pick the face or plane and press `Shift+S` — the offer opens with the sketch tools. Pressing
+`Shift+S` with nothing picked also works: the status line asks for the face or plane, and the
+first tool you arm sketches on it. The toolbar and
 the offer both carry the sketch tools.
 
 **Entities:** line, polyline, rectangle (corner / centre / oblique / rounded), circle
@@ -290,6 +316,13 @@ edit; the importer warns before you commit to it.
 inside the 3MF, so reopening the project restores the editable model rather than a frozen
 mesh.
 
+**MCP control** lets an external agent drive the tab through the same kernel the GUI uses.
+Start the app with `ORCA_CAD_MCP=1` (socket `/tmp/orca-cad-mcp.sock`) or
+`ORCA_CAD_MCP=/path/to.sock`; the CAD feature must be enabled too. Linux and macOS only. A
+command that would change the document is refused while the Design tab is busy with it — a
+rebuild, an open feature card or a sketch session — so the agent and the user never edit the
+same thing at once.
+
 ---
 
 ## View controls

docs/CAD/design_tab_pr_description.md

@@ -20,13 +20,14 @@ design intent that both steps discard. A part modified after slicing should retu
 feature history, not to a mesh. Keeping the CAD model inside the slicer preserves that
 loop — the nozzle diameter, the build volume and the material are known at design time.
 
-For the integration case in full: [design_tab_upstream_portability.md](docs/design_tab_upstream_portability.md).
+For the integration case in full: [design_tab_upstream_portability.md](design_tab_upstream_portability.md).
 
 ## How it is built
 
 The `SLIC3R_CAD` CMake flag (default ON) gates the entire tab. With it OFF the tab is not
 compiled and the deps prefix matches upstream exactly — the dependency diff is one line in
-OCCT's CMake: `BUILD_MODULE_ModelingAlgorithms=OFF → ON`.
+OCCT's CMake: `BUILD_MODULE_ModelingAlgorithms=OFF → ON`. At run time the tab is off until
+Preferences → CAD feature (experimental) is enabled.
 
 Measured cost table: [cad_dependency_weight.md](docs/cad_dependency_weight.md).
 
@@ -55,7 +56,7 @@ circle-line tangency solver abort and the internal-thread reference) are fixed.
 
 The vendored solver in `src/libslic3r/slvs/` is **GPL-3.0** (see `src/libslic3r/slvs/LICENSE`),
 not LGPL. The combined work is distributable under AGPL-3.0. See the Licensing section of
-[design_tab_upstream_portability.md](docs/design_tab_upstream_portability.md) for the
+[design_tab_upstream_portability.md](design_tab_upstream_portability.md) for the
 AGPLv3/GPLv3 compatibility argument; this point should be confirmed with upstream explicitly.
 
 ## Not verified

docs/CAD/design_tab_upstream_portability.md

@@ -1,162 +1,77 @@
-# Design (CAD) tab — upstream integration brief
+# Design (CAD) tab — integration surface
 
-**Question:** can the Design tab (sketch-first parametric CAD: sketch → constrain →
-extrude/revolve/fillet/hole/thread/shell, multi-body, undo, 3MF persistence) land in
-mainline OrcaSlicer?
+What the Design tab adds to OrcaSlicer, what it touches that upstream already has, and the
+constraints that come with it. The dependency cost is measured separately in
+[cad_dependency_weight.md](cad_dependency_weight.md); this page does not repeat its numbers.
 
-**Answer: yes, and the ask is far smaller than previously believed.** OCCT is *already*
-an OrcaSlicer dependency. We are not asking upstream to adopt a new library; we are
-asking it to widen one it already builds, at a measured cost of **3.77 MiB on Windows**.
+## Two gates
 
-> ### Corrections to the 2026-06-21 assessment
-> That revision was written before the persistence work landed and got two load-bearing
-> facts wrong. Both are corrected here from direct measurement of the branch:
->
-> 1. **"The real blocker: OCCT … a dependency mainline OrcaSlicer has never carried."**
->    **False.** `deps/OCCT/` exists at the merge-base and upstream links it from
->    `Format/STEP.cpp`, `Format/svg.cpp`, and `Shape/TextShape.cpp`. Our entire
->    dependency diff is **one line**: `BUILD_MODULE_ModelingAlgorithms=OFF → ON`.
-> 2. **"vendored SolveSpace solver … LGPL."** **False.** `src/libslic3r/slvs/LICENSE` is
->    **GPL-3.0**, not LGPL. This is fine (see Licensing) but must not be misstated.
->
-> It also claimed "no changes to Model" — no longer true; 3MF recipe persistence adds one
-> `std::string` to `Model`.
+- **Compile time: `SLIC3R_CAD`** (`CMakeLists.txt`, default ON in this tree). OFF builds no
+  CAD code at all and leaves the OCCT deps prefix identical to upstream. ON also turns on
+  OCCT's `ModelingAlgorithms` module (`deps/OCCT/OCCT.cmake`).
+- **Run time: Preferences → CAD feature (experimental)** (`enable_cad_feature`, default OFF).
+  Off, the Design page and the MCP control socket are not created, the Prepare-toolbar Sketch
+  and Primitive gizmos cannot be selected, and the Design-only preferences are hidden: Prepare
+  behaves as it does without the feature. A project that carries a CAD recipe still loads,
+  keeps the recipe and writes it back unchanged.
 
-## Measured shape of the change
+## Dependencies
 
-Against merge-base `449a4cf9fc` (34 commits ahead):
+OCCT is already an upstream dependency (STEP import, SVG, text shapes). The Design tab adds no
+library; it widens the OCCT build by one module, which builds three extra toolkits — TKFillet,
+TKOffset and TKFeat — of which the first two are linked. The module flag is all-or-nothing, so
+TKFeat is built although nothing references it.
 
-| | files | lines |
-|---|---:|---:|
-| **New files** | 138 | +61,720 |
-| **Modified upstream files** | 23 | +457 / −75 |
-| **Deleted upstream files** | 0 | — |
+The constraint solver is vendored in `src/libslic3r/slvs/`: a self-contained subset of
+SolveSpace (`libslvs`), GPL-3.0, no external dependencies. GPLv3 §13 and AGPLv3 §13 permit the
+combination with OrcaSlicer's AGPL-3.0.
 
-The 62 kLOC headline is inflated by localization. The feature itself:
+## Footprint in upstream files
 
-| area | LOC | files |
-|---|---:|---:|
-| kernel (`src/libslic3r/`) | 15,828 | 37 |
-| GUI (`src/slic3r/`) | 19,544 | 14 |
-| tests (Catch2) | 2,567 | 6 |
-| i18n (unrelated; strip from the CAD PR) | 23,438 | 77 |
+Almost all of the change is new files under `src/libslic3r/CAD/`, `src/slic3r/GUI/CAD/`,
+`src/libslic3r/slvs/` and `tests/`. The hooks into existing code are small and null-guarded:
 
-**99.3 % of the diff is new files.** The negotiable surface is 457 added lines across 23
-files, and nothing upstream is deleted. The largest single hook is `GLCanvas3D.cpp`
-(+110/−2): an `m_design_sketch_tool` member plus render/mouse/key hooks, **every one
-already null-guarded** — which is why the compile-time gate below is cheap.
+- `GLCanvas3D` — a `DesignSketchTool` pointer plus render, mouse and key hooks, each a no-op
+  when no Design canvas owns it.
+- `MainFrame` — the Design page and the Edit menu routing Undo/Redo to it while it is shown.
+- `Plater` — the "no geometry" warning distinguishes a recipe-only project.
+- `Model` — one `std::string cad_recipe`, empty for non-CAD projects.
+- `bbs_3mf` — reading and writing that string (below).
+- `Preferences`, `GUI_App` — the two preferences.
 
-No changes to the slicing pipeline (Print/PrintObject/Layer/GCode), Tab, or the
-printer-profile/config system.
+Nothing in the slicing pipeline (Print, PrintObject, Layer, GCode), Tab, or the profile and
+config system changes.
 
-## The dependency ask, precisely
-
-Not "adopt OCCT" — **widen the existing OCCT build**:
-
-```diff
--        -DBUILD_MODULE_ModelingAlgorithms=OFF
-+        -DBUILD_MODULE_ModelingAlgorithms=ON
-```
-
-Cost, measured from the shipped Windows artifact (42 OCCT DLLs, 45.43 MiB total):
-
-| toolkit | size | note |
-|---|---:|---|
-| `TKFillet.dll` | 2.02 MiB | only exists with the flag ON |
-| `TKOffset.dll` | 1.75 MiB | only exists with the flag ON |
-| **delta** | **3.77 MiB** | Windows only (OCCT is Shared on Win, Static elsewhere) |
-
-`TKBool` is *not* part of the delta — upstream's `DataExchange` already pulls it in
-transitively. On macOS/Linux OCCT links statically, so the cost is only the code actually
-referenced, not a 3.77 MiB floor.
-
-**Unmeasured, and we should measure before the call:** clean-deps build-time delta with
-the flag ON vs OFF, and the resulting CI runner-minute cost. Do not guess these at him.
-
-## Licensing
-
-- Vendored solver `src/libslic3r/slvs/` — **GPL-3.0**, 9,339 LOC, © Jonathan Westhues,
-  a self-contained subset of SolveSpace (`libslvs`). No external dependencies.
-- OrcaSlicer — **AGPL-3.0** (`LICENSE.txt`).
-
-GPLv3 §13 expressly permits combining a GPLv3 work with an AGPLv3 work; AGPLv3 §13 grants
-the converse. The combined work is distributable under AGPL-3.0 with the solver's GPLv3
-terms preserved. This is a favourable direction (GPLv3 → into an AGPLv3 project), but it
-is a point to **confirm explicitly with upstream**, not to assert unilaterally.
-
-Open question for SoftFever: keep the solver **vendored** (current: pinned, no submodule,
-no external build) or move it to `deps/` as a fetched external? Vendoring costs us
-upstream-sync burden; `deps/` costs build complexity.
-
-## The one irreversible decision: the 3MF format
-
-Persistence adds an **optional** archive entry and one field:
-
-```cpp
-// Model.hpp
-std::string cad_recipe;   // empty for non-CAD projects
-```
+## The 3MF entry
 
 ```
-Metadata/orca_cad.bin   // written only when cad_recipe is non-empty
+Metadata/orca_cad.bin      written only when cad_recipe is non-empty
+Metadata/SnapOrca_cad.bin  legacy name: read, never written; loses to orca_cad.bin
 ```
 
-Readers that do not know the entry ignore it; writers skip it entirely when empty. So
-existing projects are bit-identical and old readers are unaffected. Good.
+Readers that do not know the entry ignore it and writers skip it when the recipe is empty, so
+projects without a design are byte-identical and older readers are unaffected. The reader caps
+the entry at 1 GiB.
 
-**But the moment upstream ships this, it owns forward-compatibility forever.** Three
-things should be settled *before* the first release, because none can be changed after:
+The entry is a cereal `PortableBinaryArchive`, portable across endianness and word size. Its
+layout is versioned:
 
-1. **Name.** Renamed to `Metadata/orca_cad.bin`.
-2. **Encoding.** The recipe is an opaque **cereal `PortableBinaryArchive`** blob whose
-   layout is the field order of `CadFeature::serialize`. Portable across endianness and
-   word size — *not* across a field reorder. Append-only is currently a convention held by
-   discipline, not by any check.
-3. **Embedded BRep.** `Import` features embed OCCT's ASCII BRep for the imported solid,
-   which couples saved project files to an OCCT BRep revision. Alternative: re-import from
-   the source STEP and store only a reference. Worth deciding deliberately.
+- **v5 and later** frame every feature separately, so fields are appended to
+  `CadFeature::serialize` without a version bump and an older reader skips what it does not
+  know. Optional document-level data (variables, body names, origin, colours, the
+  auto-close setting) follows in trailing blocks that a reader stops at cleanly when absent.
+- **v4** is the flat layout, read by the frozen `CadFeature::load_flat_v4`, which must never
+  change.
 
-**Concrete gap we should close before the call.** `test_caddocument.cpp` covers the
-in-memory round-trip and correctly refuses a version-999 blob — but there is **no
-checked-in v1 fixture on disk**. A reordered field in `CadFeature::serialize` would pass
-the entire suite while silently breaking every previously-saved project. Ship a golden
-`.bin` fixture generated today plus a test that loads it; that is the only thing that will
-hold the format still once real users have files.
+Checked-in fixtures `tests/data/cad_recipe_v3.bin`, `cad_recipe_v4.bin` and
+`cad_recipe_v5.bin` hold the format still: `test_caddocument.cpp` loads them and checks what
+they contain, so a reordered field fails the suite instead of breaking saved projects.
 
-## Proposed PR decomposition
+`Import` features embed OCCT's ASCII BRep of the imported solid, which ties a saved project to
+a BRep revision OCCT can read.
 
-35 kLOC in one PR is not reviewable. Behind the flag, slices 1–4 are behaviour-neutral for
-existing users:
+## Undo
 
-1. **Build gate + OCCT flag + Windows packaging guard.** `-DSLIC3R_CAD=ON/OFF`, default
-   **OFF**. Flips `ModelingAlgorithms=ON`. Includes the guard that asserts every linked
-   OCCT toolkit has a shipped DLL (already on both forks: `546cef5f42`). ← *this is what
-   makes SoftFever's "parallel build" a one-line CI matrix entry.*
-2. **Vendored `slvs` solver** + its Catch2 tests. No GUI, no OCCT.
-3. **CAD kernel** (`CadDocument`, `SketchEngine`, `GeometryEngine`, `Sketch*`) + kernel
-   tests. Headless, no GUI.
-4. **3MF recipe persistence** + golden-fixture regression test.
-5. **GUI Design tab** (`DesignPanel`, `DesignCanvas`, `DesignSketchTool`, `GLGizmoSketch`)
-   + the 23 upstream hooks.
-
-## Agenda for the call
-
-Questions only SoftFever can answer:
-
-- Does OrcaSlicer *want* to be a CAD-integrated slicer? (Strategic; everything else is mechanical.)
-- Default of `SLIC3R_CAD` at merge time, and when it flips ON.
-- Vendored solver vs `deps/` external; and confirmation of the GPLv3/AGPLv3 combination.
-- Project-file format: neutral name, encoding, embedded-BRep policy, and who owns v1 forward-compat.
-- Undo/redo: the Design tab has its own stack; integrate with Orca's snapshot system or keep separate?
-- Does he want the i18n work (Romanian, +23 kLOC) as a wholly separate PR? (Yes, almost certainly.)
-
-## Verdict
-
-Portability **high**. The prior "does upstream want OCCT" framing was wrong — OCCT is
-already there. What remains is a 3.77 MiB dependency widening, a compile-time gate that
-the existing null-guards make cheap, and one file-format decision that must be made before
-the first release rather than after.
-
----
-*Revised 2026-07-10 from direct measurement of `cad-mainline` @ `546cef5f42` vs upstream
-merge-base `449a4cf9fc`. Supersedes the 2026-06-21 read-only assessment.*
+The Design tab keeps its own history (`CadDocument` checkpoints), separate from the Plater's
+snapshot stack. The Edit menu's Undo/Redo drive whichever of the two belongs to the page on
+screen.

docs/CAD/ux/interaction-model.md

@@ -72,10 +72,11 @@ which is what makes the destructive path unrepresentable rather than merely unli
 own handlers so it can consume the event before them:
 
 ```cpp
-RIGHT_DOWN: remember the press position and the clock, then Skip()   // the canvas still seeds the orbit
+RIGHT_DOWN: remember the press position, clear `travelled`, then Skip() // the canvas still seeds the orbit
+MOTION:     travelled |= drift from the press > 3 px                   // an orbit that came back still orbited
 
 RIGHT_UP:   terminated = sketch_tool.take_right_consumed();          // read-and-clear, always
-            is_click   = drift <= 3 px && dt <= 200 ms;              // both budgets, or it was navigation
+            is_click   = !travelled && drift <= 3 px;                // otherwise it was navigation
             if (callback && !terminated && !inline_busy && is_click) {
                 select_at_screen(press.x, press.y);                  // raycast at the PRESS, not the release
                 on_context_menu(ClientToScreen(press));
@@ -84,8 +85,9 @@ RIGHT_UP:   terminated = sketch_tool.take_right_consumed();          // read-and
             Skip();                                                  // orbit / pan / the handlers underneath
 ```
 
-Two independent budgets because the two failure modes are independent: drift alone still popped a
-menu at the end of a slow, careful orbit. `take_right_consumed()` is how a right-click that
+Only distance decides, never time (charter §6.2: no timing-dependent gestures): a slow, deliberate
+right-click is still a click. The drift is tracked over the whole press, not just at release, so a
+careful orbit that ends where it started does not pop a menu. `take_right_consumed()` is how a right-click that
 already meant something to the armed sketch tool (terminate a chain, drop an edit-op) declines to
 also mean "open a menu".
 
@@ -107,7 +109,7 @@ also mean "open a menu".
 | **Transient — popup menu** | run the entry | — | close the menu | run the highlighted entry |
 | **any** | — | — | *never* deletes, discards or rolls back | — |
 
-Right-hold-and-drag is not in the table on purpose: past 3 px or 200 ms it is navigation, and
+Right-hold-and-drag is not in the table on purpose: once it has travelled past 3 px it is navigation, and
 navigation does not transition the state machine.
 
 ## 4. Visual scaffolding

docs/CAD/ux/mockups/gen_offer_table.py

@@ -42,6 +42,12 @@ def cstr(s):
     return '"' + s.replace("\\", "\\\\").replace('"', '\\"') + '"'
 
 
+def tstr(s):
+    # User-facing text: wrapped in the no-op L() marker so xgettext puts it in the catalogue.
+    # The DesignPanel translates it at use; without the marker it compiles and never translates.
+    return "nullptr" if s is None else "L(" + cstr(s) + ")"
+
+
 def main():
     A = json.load(open(ATLAS, encoding="utf-8"))
     sels = [s["id"] for s in A["selections"]]
@@ -61,6 +67,10 @@ def main():
         "",
         "#include <cstdint>",
         "",
+        "#ifndef L",
+        "#define L(s) s   // gettext marker, as in slic3r/GUI/I18N.hpp",
+        "#endif",
+        "",
         "namespace Slic3r { namespace GUI {",
         "",
         "// What the viewport has selected. Ordered as in tool_atlas.json; the bitmask in",
@@ -83,7 +93,7 @@ def main():
         "//   nullptr          -> kernel support exists, no GUI path yet (row shows disabled)",
         "struct OfferVerb {",
         "    const char* id;",
-        "    const char* name;        // drawing-office word (L10); translated at use with wxGetTranslation",
+        "    const char* name;        // drawing-office word (L10); marked L(); translated at use",
         "    int         row;         // 0..7, the ratified index — NEVER reorder",
         "    const char* key;         // shortcut shown in the row, or nullptr",
         "    const char* action;",
@@ -106,7 +116,7 @@ def main():
         "static const char* const kOfferRowNames[] = {",
     ]
     for s in A["slots"]:
-        lines.append(f'    "{s["label"]}",')
+        lines.append(f'    {tstr(s["label"])},')
     lines += [
         "};",
         f"static const int kOfferRowCount = {len(slots)};",
@@ -131,12 +141,12 @@ def main():
         n = v.get("needs") or {}
         lines.append(
             "    {%s, %s, %d, %s, %s, %s, 0x%08xu, %d, %d, %s, %s, %s, %s, %s}," % (
-                cstr(v["id"]), cstr(v["name"]), slots.index(v["slot"]),
-                cstr(v.get("key")), cstr(v.get("action")), cstr(v.get("refusal")),
+                cstr(v["id"]), tstr(v["name"]), slots.index(v["slot"]),
+                cstr(v.get("key")), cstr(v.get("action")), tstr(v.get("refusal")),
                 mask, n.get("bodies", 0), n.get("sketches", 0),
                 "true" if n.get("sheet") else "false",
                 "true" if v.get("mode") == "sketch" else "false",
-                cstr(v.get("family")), cstr(v.get("icon")), cstr(v.get("hint"))))
+                tstr(v.get("family")), cstr(v.get("icon")), tstr(v.get("hint"))))
     lines += [
         "};",
         f"static const int kOfferVerbCount = {len(A['verbs'])};",

docs/CAD/ux/tool_atlas.json

@@ -326,7 +326,7 @@
       "id": "rib",
       "name": "Rib",
       "slot": "add",
-      "key": null,
+      "key": "R",
       "feature": "Rib",
       "mcp": "rib",
       "accepts": [
@@ -343,7 +343,7 @@
     },
     {
       "id": "boolean",
-      "name": "Union",
+      "name": "Join",
       "slot": "add",
       "key": "Shift+B",
       "feature": "Boolean",
@@ -354,7 +354,7 @@
       "needs": {
         "bodies": 2
       },
-      "refusal": "Boolean needs two bodies — create or import a second solid",
+      "refusal": "Boolean needs two bodies — add or import a second one",
       "gui": true,
       "action": "btn:bool#0",
       "icon": "design_boolean",
@@ -373,7 +373,7 @@
       "needs": {
         "bodies": 2
       },
-      "refusal": "Boolean needs two bodies — create or import a second solid",
+      "refusal": "Boolean needs two bodies — add or import a second one",
       "gui": true,
       "action": "btn:bool#1",
       "mode": null,
@@ -393,7 +393,7 @@
       "needs": {
         "bodies": 2
       },
-      "refusal": "Boolean needs two bodies — create or import a second solid",
+      "refusal": "Boolean needs two bodies — add or import a second one",
       "gui": true,
       "action": "btn:bool#2",
       "mode": null,
@@ -483,7 +483,7 @@
       "needs": {
         "sheet": true
       },
-      "refusal": "target is not a sheet body",
+      "refusal": "Thicken Surface needs a surface body — make one with a Surface tool first",
       "gui": true,
       "action": "fly:surface#5",
       "icon": "design_thicken",
@@ -507,7 +507,7 @@
       "gui": true,
       "action": "key:S+H",
       "icon": "design_hole",
-      "hint": "Drill a hole, centred on a picked face or placed on a plane"
+      "hint": "Drill a hole, centerd on a picked face or placed on a plane"
     },
     {
       "id": "thread",
@@ -543,7 +543,7 @@
       "needs": {
         "bodies": 1
       },
-      "refusal": "Shell needs a solid body",
+      "refusal": "Shell needs a solid body — add or import one first",
       "gui": true,
       "action": "key:S+K",
       "icon": "design_shell",
@@ -569,7 +569,7 @@
       "needs": {
         "bodies": 1
       },
-      "refusal": "Create a solid body to cut first",
+      "refusal": "Cut needs a solid body — add or import one first",
       "gui": true,
       "action": "key:S+X",
       "icon": "design_cut",
@@ -594,7 +594,7 @@
       "needs": {
         "bodies": 1
       },
-      "refusal": "Split needs a solid body",
+      "refusal": "Split needs a solid body — add or import one first",
       "gui": false,
       "action": null,
       "icon": null,
@@ -677,7 +677,7 @@
       "needs": {
         "sheet": true
       },
-      "refusal": "target is not a sheet body",
+      "refusal": "Surface Offset needs a surface body — make one with a Surface tool first",
       "gui": true,
       "action": "fly:surface#4",
       "icon": "design_offset",
@@ -699,7 +699,7 @@
       "needs": {
         "bodies": 1
       },
-      "refusal": "Create a solid body to pattern first",
+      "refusal": "Pattern needs a solid body — add or import one first",
       "gui": true,
       "action": "btn:pat#0",
       "icon": "design_array",
@@ -721,7 +721,7 @@
       "needs": {
         "bodies": 1
       },
-      "refusal": "Create a solid body to pattern first",
+      "refusal": "Pattern needs a solid body — add or import one first",
       "gui": true,
       "action": "btn:pat#1",
       "mode": null,
@@ -768,7 +768,7 @@
       "needs": {
         "bodies": 1
       },
-      "refusal": "Pattern on curve needs a body and a curve",
+      "refusal": "Pattern on Curve needs a body and a curve",
       "gui": false,
       "action": null,
       "icon": null,
@@ -816,11 +816,11 @@
       "needs": {
         "bodies": 2
       },
-      "refusal": "A mate needs two coordinate systems",
+      "refusal": "Mate needs two coordinate systems — create them first",
       "gui": true,
       "action": "fly:placement#2",
       "icon": "design_c_coincident",
-      "hint": "Assembly: align two CoordSys features (fastened, planar, revolute, slider, cylindrical)"
+      "hint": "Assembly: align two coordinate systems (fastened, planar, revolute, slider, cylindrical)"
     },
     {
       "id": "align",
@@ -835,7 +835,7 @@
       "needs": {
         "bodies": 1
       },
-      "refusal": "Align needs a body",
+      "refusal": "Align needs a body — add or import one first",
       "gui": false,
       "action": null,
       "icon": null,
@@ -885,7 +885,7 @@
     },
     {
       "id": "coordsys_v",
-      "name": "Coord Sys",
+      "name": "Coordinate system",
       "slot": "reference",
       "key": "Shift+C",
       "feature": "CoordSys",
@@ -972,7 +972,7 @@
     },
     {
       "id": "mass_props",
-      "name": "Mass",
+      "name": "Volume and area",
       "slot": "reference",
       "key": null,
       "feature": null,
@@ -1003,14 +1003,15 @@
       "feature": null,
       "mcp": "check_interference",
       "accepts": [
+        "body_solid",
         "bodies_2"
       ],
       "needs": {
         "bodies": 2
       },
-      "refusal": null,
-      "gui": false,
-      "action": null,
+      "refusal": "Interference needs at least two bodies",
+      "gui": true,
+      "action": "btn:interference",
       "icon": null,
       "hint": "Check whether two bodies overlap — reports, changes nothing"
     },
@@ -1082,7 +1083,7 @@
     },
     {
       "id": "colour",
-      "name": "Colour",
+      "name": "Color",
       "slot": "modify",
       "key": null,
       "feature": null,
@@ -1104,7 +1105,7 @@
       "gui": true,
       "action": "btn:colour",
       "icon": "color_palette",
-      "hint": "Set the selected body's display colour"
+      "hint": "Set the selected body's display color"
     },
     {
       "id": "delete",
@@ -1227,7 +1228,7 @@
     },
     {
       "id": "sk_rect_center",
-      "name": "Centre rectangle",
+      "name": "Center rectangle",
       "slot": "create",
       "key": null,
       "feature": "Sketch",
@@ -1296,7 +1297,7 @@
     },
     {
       "id": "sk_circle",
-      "name": "Centre circle",
+      "name": "Center circle",
       "slot": "create",
       "key": "C",
       "feature": "Sketch",
@@ -1411,7 +1412,7 @@
     },
     {
       "id": "sk_arc_center",
-      "name": "Centre-point arc",
+      "name": "Center-point arc",
       "slot": "create",
       "key": null,
       "feature": "Sketch",
@@ -1453,7 +1454,7 @@
       "action": "key:S",
       "family": "Slot",
       "icon": "design_slot",
-      "hint": "Slot — two centerline ends, then end radius"
+      "hint": "Slot — two centerline ends, then the width"
     },
     {
       "id": "sk_slot_arc",
@@ -1567,7 +1568,7 @@
       "mode": "sketch",
       "family": "Polygon",
       "icon": "design_polygon",
-      "hint": "Triangle — click centre, then a vertex"
+      "hint": "Triangle — click center, then a vertex"
     },
     {
       "id": "sk_poly_4",
@@ -1590,7 +1591,7 @@
       "mode": "sketch",
       "family": "Polygon",
       "icon": "design_polygon",
-      "hint": "Square — click centre, then a vertex"
+      "hint": "Square — click center, then a vertex"
     },
     {
       "id": "sk_poly_5",
@@ -1613,7 +1614,7 @@
       "mode": "sketch",
       "family": "Polygon",
       "icon": "design_polygon",
-      "hint": "Pentagon — click centre, then a vertex"
+      "hint": "Pentagon — click center, then a vertex"
     },
     {
       "id": "sk_polygon",
@@ -1636,7 +1637,7 @@
       "action": "btn:poly#6",
       "family": "Polygon",
       "icon": "design_polygon",
-      "hint": "Hexagon — click centre, then a vertex"
+      "hint": "Hexagon — click center, then a vertex"
     },
     {
       "id": "sk_poly_8",
@@ -1659,7 +1660,7 @@
       "mode": "sketch",
       "family": "Polygon",
       "icon": "design_polygon",
-      "hint": "Octagon — click centre, then a vertex"
+      "hint": "Octagon — click center, then a vertex"
     },
     {
       "id": "sk_poly_12",
@@ -1682,7 +1683,7 @@
       "mode": "sketch",
       "family": "Polygon",
       "icon": "design_polygon",
-      "hint": "Dodecagon — click centre, then a vertex"
+      "hint": "Dodecagon — click center, then a vertex"
     },
     {
       "id": "sk_poly_inscribed",
@@ -2048,7 +2049,7 @@
     {
       "id": "constrain",
       "name": "Constrain sketch",
-      "slot": "modify",
+      "slot": "reference",
       "key": null,
       "feature": "Sketch",
       "mcp": null,
@@ -2067,7 +2068,8 @@
       "note": [
         "Same verb, model-mode vocabulary: offered when a SKETCH is selected (bit 14, SkLoop), the",
         "state a user is in right after finishing one. Without this row the only way in was the",
-        "toolbar icon, and constraints read as absent — see the Onshape-comparison report."
+        "toolbar icon, and constraints read as absent — see the Onshape-comparison report.",
+        "It sits in the Reference row, the address the sketch-mode Constrain has: one verb, one row."
       ]
     },
     {