Merge origin/main into feat/placement-interaction-overhaul

Resolve 7 conflicts keeping our snapping migration + floorplan perf work as
source of truth, combined with main's MEP run-continuation / Alt-detach /
latch handles. Rebuilt two import blocks the auto-merge silently truncated
(node-arrow-handles.tsx, duct-fitting/move-tool.tsx).

Verified: tsc clean across core/viewer/editor/nodes/mcp, 451 tests pass,
biome clean. Floorplan view-transform re-render storm confirmed pre-existing
(not introduced by this merge).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/nodes/src/pipe-trap/definition.ts

@@ -27,7 +27,7 @@ export const pipeTrapDefinition: NodeDefinition<typeof PipeTrapNode> = {
     metadata: {},
     position: [0, 0, 0],
     rotation: 0,
-    diameter: 1.5,
+    diameter: 2,
     pipeMaterial: 'pvc',
     armLengthM: 0,
   }),

packages/nodes/src/pipe-trap/geometry.ts

@@ -1,9 +1,14 @@
-import { Group, Mesh, TorusGeometry, Vector3 } from 'three'
+import { DoubleSide, Group, Mesh, SphereGeometry, TorusGeometry, Vector3 } from 'three'
 import { buildSection, INCHES_TO_METERS } from '../duct-segment/geometry'
 import { createPipeMaterial } from '../pipe-segment/geometry'
 import type { PipeTrapNode } from './schema'
 
 const BEND_SEGMENTS = 24
+const RADIAL_SEGMENTS = 20
+/** Sphere hubs filling the U-bend → stub joints read as a coupling and,
+ *  more importantly, hide the wedge gap left where the horizontal arm's
+ *  flat end cap meets the bend's upward-facing opening at 90°. */
+const HUB_RADIUS_FACTOR = 1.12
 
 /** Inlet drop and arm reach in pipe radii — keeps the trap proportional
  *  to its size without per-size tuning. */
@@ -19,8 +24,12 @@ const ARM_REACH_RADII = 3.2
 export function buildPipeTrapGeometry(node: PipeTrapNode): Group {
   const group = new Group()
   const material = createPipeMaterial({ pipeMaterial: node.pipeMaterial, system: 'waste' })
+  // Double-sided so the thin pipe walls don't drop out at grazing angles,
+  // which read as cuts/holes on the bend and stub ends.
+  material.side = DoubleSide
   const radius = (node.diameter * INCHES_TO_METERS) / 2
   const bendR = radius * 1.6
+  const hubRadius = radius * HUB_RADIUS_FACTOR
 
   // U-bend: half torus in the XY plane, opening upward. Sits so its two
   // tops are at y = bendR (the inlet riser and the arm rise).
@@ -49,6 +58,19 @@ export function buildPipeTrapGeometry(node: PipeTrapNode): Group {
   const arm = buildSection(armStart, armEnd, radius, material, 'pipe-trap-arm')
   if (arm) group.add(arm)
 
+  // Coupling hubs at the two U-bend tops where the straight stubs meet the
+  // torus. They fill the 90° miter wedge (the visible "cut") and read as
+  // the trap's slip-joint nuts.
+  for (const [i, center] of [
+    new Vector3(0, bendR, 0),
+    new Vector3(bendR * 2, bendR, 0),
+  ].entries()) {
+    const hub = new Mesh(new SphereGeometry(hubRadius, RADIAL_SEGMENTS, 12), material)
+    hub.name = `pipe-trap-hub-${i}`
+    hub.position.copy(center)
+    group.add(hub)
+  }
+
   return group
 }
 

packages/nodes/src/pipe-trap/tool.tsx

@@ -27,7 +27,7 @@ const PipeTrapTool = () => {
   const activeLevelId = useViewer((s) => s.selection.levelId)
   const [cursor, setCursor] = useState<[number, number, number] | null>(null)
   const [yaw, setYaw] = useState(0)
-  const [diameter] = useState(1.5)
+  const [diameter] = useState(pipeTrapDefinition.defaults().diameter)
   const yawRef = useRef(0)
   const diameterRef = useRef(diameter)
   diameterRef.current = diameter