diff --git a/wiki/architecture/tools.md b/wiki/architecture/tools.md
index e933979f..a1a20f7d 100644
--- a/wiki/architecture/tools.md
+++ b/wiki/architecture/tools.md
@@ -60,7 +60,9 @@ export function MyTool() {
 
 - **Tools mutate `useScene` for committed changes and `useLiveTransforms` for ephemeral drag state.** A tool's end-of-interaction write (click-to-commit, release-to-commit) goes to `useScene` and is captured in undo history. Per-mouse-move previews go to `useLiveTransforms` so history and subscribers aren't spammed.
 - **Live-drag exception for direct mesh transforms.** During an active drag a tool may apply a transform offset directly to `sceneRegistry.nodes.get(id).position`/`rotation`/`scale` *when and only when* the same offset is mirrored into `useLiveTransforms` for that node. This exception exists because the 3D renderers don't reconcile `useLiveTransforms` onto `mesh.position` yet; once a `LiveTransformSystem` does that, this exception goes away. Conditions:
-  - The mesh offset must mirror the `useLiveTransforms` entry (same delta on both), so anything reading `useLiveTransforms` sees the same preview as the 3D view.
+  - The mesh offset must mirror the `useLiveTransforms` entry (**same exact value**, not "same conceptual translation"), so anything reading `useLiveTransforms` sees the same preview as the 3D view. `ParametricNodeRenderer` (used for every kind that ships `def.geometry`) binds `<group position={liveTransform.position}>` via React — every Zustand notification re-renders and reconciles the group's position back to whatever value `useLiveTransforms` holds. If `mesh.position.set(delta)` and `useLiveTransforms.set({ position: someOtherValue })` disagree, the two writes fight every frame and the user sees jitter during the drag.
+  - **For position-based kinds (spawn / item / column)**: the `position` field on the node IS the group's local-frame position, so `useLiveTransforms.position` should hold the live world position of the node (matches the eventual `scene.update`).
+  - **For polygon-based kinds (slab / fence / ceiling / wall)**: the node has no `position` field — the canonical group position is `[0,0,0]` with geometry built in level-local coords. `useLiveTransforms.position` must hold the **delta** the tool wants to translate by (`[deltaX, 0, deltaZ]`), not the world location of the polygon's center. The cursor sphere position (which IS the translated polygon center) is tracked separately via React `useState`, not `useLiveTransforms`.
   - The offset must be cleared on tool unmount, cancel, *and* commit — both `mesh.position.set(0, 0, 0)` and `useLiveTransforms.clear(id)`.
   - The tool must not generate or mutate geometry in this path — only transform writes. Geometry generation still belongs in a core system.
 - **No business logic in tools** — delegate geometry/constraint rules to core systems.