supports-edges draw toggle — last row of the graph settings' first section

Off hides supports edges from the canvas: the renderer skips them when
building the shaft/head paths (draw-only — the physics sim still feels
them and detail cards still list them; settings never shift the graph).
Server-persisted with the rest (render-settings.json); sanitizer takes
real booleans only, anything else (missing key, legacy file) loads ON —
today's look. Toggle row styled as the Background-colors row; sanitiser
pinned in render-settings.test.

components/graph-canvas.ts

@@ -1232,11 +1232,14 @@ export class GraphCanvasRenderer {
 		// Edge shafts + arrowheads: tip lands on the target disc edge. Both
 		// relation types draw the same arrow for now — the double-shaft
 		// glyph was rejected (2026-09-15); differentiation is pending a new
-		// approach. CanvasEdge.type is plumbed for whatever comes next.
+		// approach. CanvasEdge.type is plumbed for whatever comes next —
+		// except the supports draw toggle (owner, 2026-09-29): off skips
+		// the paths entirely (a draw-only hide; the sim still feels them).
 		const arrowLen = settings.arrowLength;
 		const shafts = new Path2D();
 		const heads = new Path2D();
 		for (const e of data.edges) {
+			if (!settings.showSupports && e.type === "supports") continue;
 			if (!isVisible(e.from) || !isVisible(e.to)) continue;
 			const a = this.nodeById.get(e.from);
 			const b = this.nodeById.get(e.to);

components/graph-view.tsx

@@ -51,7 +51,9 @@
  *
  * Rendering settings (2026-09-13): the gear in the search panel reveals
  * five sliders (node size, edge width, arrowhead length, label size, the
- * zoom threshold) plus the cluster-labels checkbox. SERVER-persisted
+ * zoom threshold), the supports-edges draw toggle (2026-09-29: off hides
+ * supports edges from the canvas — draw-only; physics and detail cards
+ * still see them), and the cluster-labels checkbox. SERVER-persisted
  * (data/render-settings.json via /api/graph/render-settings): loaded
  * once after mount, saved debounced on every user change — one source
  * of truth shared by every browser. The label-zoom slider is log-scaled
@@ -528,6 +530,20 @@ function GraphSettingsControl({
 								onChange={(p) =>
 									changeSettings((cur) => ({ ...cur, labelZoom: fromLadderPosition(p, LABEL_ZOOM_LADDER) }))}
 							/>
+							{/* Supports draw toggle (owner, 2026-09-29): hides the single-line
+							    supports edges from the canvas — follows (⟹-meant) stay. Draw-only:
+							    physics + detail cards still see them. Last row of the FIRST
+							    section; the border-t below starts Regions. */}
+							<label className="flex cursor-pointer items-center justify-between text-[11px] text-muted-foreground">
+								<span>Supports edges</span>
+								<input
+									type="checkbox"
+									checked={settings.showSupports}
+									onChange={(e) =>
+										changeSettings((cur) => ({ ...cur, showSupports: e.target.checked }))}
+									className="accent-primary"
+								/>
+							</label>
 						{/* Regions: the blurred cluster tints. Sliders + a fixed-set
 						    dropdown for the bitmap resolution (it's a discrete
 						    choice, not a free number). Server-persisted like the

src/core/render-settings.ts

@@ -54,6 +54,11 @@ export interface GraphRenderSettings {
 	labelZoom: number;
 	/** Node + hover label font size, WORLD units (scales with camera). */
 	labelSize: number;
+	/** Draw `supports` edges at all (owner, 2026-09-29): off hides them
+	 *  from the canvas — a DRAW toggle only. The physics sim still feels
+	 *  them (settings never shift the graph: camera, one frame), and node
+	 *  detail cards still list them. */
+	showSupports: boolean;
 	/** Toggle for the cluster region labels (hulls always draw). */
 	clusterLabels: boolean;
 	/** Cluster label font size, px on screen (camera-compensated —
@@ -95,6 +100,8 @@ export function sanitizeRenderSettings(raw: unknown): GraphRenderSettings {
 		arrowLength: legacySizes ? DEFAULT_RENDER_SETTINGS.arrowLength : ladd(r.arrowLength, ARROW_LENGTH_LADDER, DEFAULT_RENDER_SETTINGS.arrowLength),
 		labelZoom: ladd(r.labelZoom, LABEL_ZOOM_LADDER, DEFAULT_RENDER_SETTINGS.labelZoom),
 		labelSize: legacySizes ? DEFAULT_RENDER_SETTINGS.labelSize : ladd(r.labelSize, LABEL_SIZE_LADDER, DEFAULT_RENDER_SETTINGS.labelSize),
+		showSupports:
+			typeof r.showSupports === "boolean" ? r.showSupports : DEFAULT_RENDER_SETTINGS.showSupports,
 		clusterLabels:
 			typeof r.clusterLabels === "boolean" ? r.clusterLabels : DEFAULT_RENDER_SETTINGS.clusterLabels,
 		clusterLabelSize: ladd(
@@ -262,6 +269,7 @@ export const DEFAULT_RENDER_SETTINGS: GraphRenderSettings = {
 	arrowLength: 2,
 	labelZoom: 4,
 	labelSize: 3,
+	showSupports: true,
 	clusterLabels: true,
 	clusterLabelSize: 14,
 	regions: DEFAULT_REGION_TUNING,

tests/render-settings.test.ts

@@ -118,6 +118,7 @@ describe("sanitizeRenderSettings", () => {
 			arrowLength: 3,
 			labelZoom: 2,
 			labelSize: 4,
+			showSupports: false,
 			clusterLabels: false,
 			clusterLabelSize: 20,
 			regions: DEFAULT_REGION_TUNING,
@@ -126,6 +127,16 @@ describe("sanitizeRenderSettings", () => {
 		assert.deepEqual(sanitizeRenderSettings(valid), valid); // every value a ladder member
 	});
 
+	test("showSupports (2026-09-29): boolean-only, default on — the draw toggle", () => {
+		// A render-only hide for supports edges: anything but a real boolean
+		// (missing key, legacy file, garbage) loads as ON (today's look); a
+		// real false round-trips untouched.
+		assert.equal(sanitizeRenderSettings({}).showSupports, true);
+		assert.equal(sanitizeRenderSettings({ showSupports: false }).showSupports, false);
+		assert.equal(sanitizeRenderSettings({ showSupports: "no" }).showSupports, true);
+		assert.equal(sanitizeRenderSettings({ showSupports: 0 }).showSupports, true);
+	});
+
 	test("the pre-2026-09-13 stored shape (flat, no regions/physics) still loads", () => {
 		// data/render-settings.json on disk predates the nested sections —
 		// those loads must get defaults, not crash, not shift anything.