Contraption Builder: terrain, vehicles, Multiply, scrolling+slick palette, Bridge/Chain audit

CHANGELOG.md

@@ -8,8 +8,30 @@ The native shim's ABI is tracked separately by `b2Version()` (currently `2`).
 
 ## [Unreleased]
 
+### Added
+
+- **Terrain objects in the Contraption Builder.** A new **TERRAIN** palette
+  section adds three pieces of static scenery the dynamic parts rest on, roll
+  down and bump into: **Platform** (a solid ledge), **Ramp** (a wedge for
+  rolling and sliding) and **Hill** (a rounded mound). Each is a static polygon
+  body, so it never falls and the Kit's sync skips it. They size, rotate (the
+  angle is baked into the outline so a static body tilts without a redraw it
+  never gets), recolour, take an adjustable grip (friction), drag, duplicate
+  and save/load like any other part — and joints can pin to them, so you can
+  hinge a part to a platform or hang a bridge from a ledge.
+- **"Terrain Run" example recipe** — a ball rolls down a ramp, over a hill and
+  onto a platform, showing the new pieces in one click.
+
 ### Fixed
 
+- **Bridge & Chain spans ignore Bouncy mode.** Building a span while the
+  **Bouncy** build option was on made every plank/link springy, so bridges and
+  chains jittered and never settled. Span segments are now always built
+  non-bouncy, regardless of the toggle, so they hang and sag predictably.
+- **Duplicating a rotated part keeps its size.** Duplicate copied the graphic's
+  *bounding box* (which inflates as a part rotates) as the new part's size, so a
+  rotated box, polygon, plank or terrain piece grew each time it was copied. It
+  now copies the stored design size instead.
 - **Kit no longer leaks image-angle cache entries across teardowns.**
   `b2kResetTables` now also clears the `sImgAngle` table, so repeatedly tearing
   a world down and rebuilding it (e.g. switching demo scene tabs) stops

README.md

@@ -53,7 +53,7 @@ That's a full, draggable, gravity-driven physics scene — see
 | **Extension** | `src/box2dxt.lcb` | The xTalk Builder (LCB) library: `foreign handler` bindings wrapped in friendly `b2…` handlers. |
 | **The Kit** | `src/box2dxt-kit.livecodescript` | A batteries-included, pure-xTalk helper (`b2k…`) that works in pixels/degrees and hides the loop. |
 | **Demo** | `examples/box2dxt-demo.livecodescript` | A self-building, multi-scene testbed showing every feature. |
-| **Contraption Builder** | `examples/box2dxt-contraption-builder.livecodescript` | An interactive GUI: drop parts (incl. images), wire up joints + motors, then Run. |
+| **Contraption Builder** | `examples/box2dxt-contraption-builder.livecodescript` | An interactive GUI: drop parts (incl. images) and terrain, wire up joints + motors, then Run. |
 | **Prebuilt binaries** | `prebuilt/` | Drop-in native libraries so you can run without a toolchain. |
 
 There are two layers you can call: