Cluster labels: topmost layer + user-facing size setting

- Draw order: the cluster-label block moves from layer 5 to THE LAST
  layer of draw() — labels can never be occluded by node labels or
  hover names (user 2026-09-17; chose "topmost" after reassessing that
  discs were never actually on top — the white-out over discs is
  source-over compositing of the 85%-alpha text over near-white node
  fill, an optical contrast flip, not a draw-order bug).
- clusterLabelSize: new persisted setting (default 14 = the old
  REGION_LABEL_SIZE constant, so rendering is pixel-identical). Screen
  px at ANY zoom (drawn at size/k — camera-compensated, UI-like, same
  law as before). Log-slider range [7, 28] puts the default dead-center
  per the house slider law. Sanitized: old persisted files (no field)
  fall back to 14.
- Panel: the Cluster labels checkbox moves from the Labels section
  into Regions (user: cluster settings live with regions), joined by
  the new "Cluster label size" slider. Labels stay decoupled from the
  Background colors compute switch, as designed on 2026-09-16.

components/graph-canvas.ts

@@ -169,7 +169,6 @@ const COMMIT_DEBOUNCE_MS = 250; // settle → ledger PUT delay (new drags cancel
  *  live-physics frame pays one tiny blit instead of 32 clusters × 4
  *  offset polygons re-rasterized at DPR 2 (the old GPU coil-whine). */
 const REGION_EVERY = 3; // live-sim frames: rebuild every Nth, blit the rest
-const REGION_LABEL_SIZE = 14;
 
 
 
@@ -1357,24 +1356,6 @@ export class GraphCanvasRenderer {
 		ctx.fillStyle = data.colors.node;
 		ctx.fill(this.nodesPath);
 
-		// 5. Cluster region labels — inverse-gated on THE zoom control.
-		// Viewer-relative by design (UI, not graph content): drawn at the
-		// world centroid with a font of REGION_LABEL_SIZE / k, which is a
-		// constant 18px on screen at any zoom.
-		if (settings.clusterLabels && regionAlpha > 0.01) {
-			ctx.save();
-			ctx.globalAlpha = regionAlpha;
-			ctx.font = `${LABEL_WEIGHT} ${REGION_LABEL_SIZE / k}px ${data.fontFamily}`;
-			ctx.textAlign = "center";
-			ctx.textBaseline = "middle";
-			for (const rm of this.regionMeta) {
-				if (!rm.label) continue;
-				ctx.fillStyle = `hsla(${rm.hue}, 55%, 78%, 0.85)`;
-				ctx.fillText(rm.label, rm.cx, rm.cy);
-			}
-			ctx.restore();
-		}
-
 		// 6. Node labels — one global gate, faded together. World-scaled
 		// with the graph (they grow as you zoom in, Obsidian-style).
 		if (nodeAlpha > 0.01) {
@@ -1413,5 +1394,26 @@ export class GraphCanvasRenderer {
 				ctx.restore();
 			}
 		}
+
+		// 8. Cluster region labels — THE TOPMOST layer (user 2026-09-16:
+		// node labels and hover names drew over them before; region labels
+		// must never be occluded by content). Inverse-gated on THE zoom
+		// control (visible zoomed-out, fading as node labels come in).
+		// Viewer-relative by design (UI, not graph content): drawn at the
+		// world centroid with a font of clusterLabelSize / k — a constant
+		// size on screen at any zoom (user-tunable since 2026-09-16).
+		if (settings.clusterLabels && regionAlpha > 0.01) {
+			ctx.save();
+			ctx.globalAlpha = regionAlpha;
+			ctx.font = `${LABEL_WEIGHT} ${settings.clusterLabelSize / k}px ${data.fontFamily}`;
+			ctx.textAlign = "center";
+			ctx.textBaseline = "middle";
+			for (const rm of this.regionMeta) {
+				if (!rm.label) continue;
+				ctx.fillStyle = `hsla(${rm.hue}, 55%, 78%, 0.85)`;
+				ctx.fillText(rm.label, rm.cx, rm.cy);
+			}
+			ctx.restore();
+		}
 	}
 }

components/graph-view.tsx

@@ -69,6 +69,7 @@ import { GraphCanvasRenderer, type GraphRenderSettings } from "./graph-canvas.ts
 import {
 	ARROW_LENGTH_RANGE,
 	CHARGE_RANGE,
+	CLUSTER_LABEL_SIZE_RANGE,
 	CLUSTER_PULL_RANGE,
 	DEPTH_BASE_RADIUS_RANGE,
 	DEPTH_SPACING_RANGE,
@@ -279,15 +280,6 @@ function GraphSettingsControl({
 								onChange={(p) =>
 									changeSettings((cur) => ({ ...cur, labelZoom: fromSliderPosition(p, LABEL_ZOOM_MIN, LABEL_ZOOM_MAX) }))}
 							/>
-							<label className="flex cursor-pointer items-center justify-between text-[11px] text-muted-foreground">
-								<span>Cluster labels</span>
-								<input
-									type="checkbox"
-									checked={settings.clusterLabels}
-									onChange={(e) => changeSettings((cur) => ({ ...cur, clusterLabels: 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
@@ -376,6 +368,33 @@ function GraphSettingsControl({
 									))}
 								</select>
 							</label>
+							{/* Cluster labels moved here 2026-09-16 (user: cluster
+							    stuff lives in the regions section). Decoupled from
+							    the Background colors switch above — labels follow
+							    their own clusterLabels toggle. Size is screen px
+							    (constant at any zoom, unlike node labels). */}
+							<label className="flex cursor-pointer items-center justify-between text-[11px] text-muted-foreground">
+								<span>Cluster labels</span>
+								<input
+									type="checkbox"
+									checked={settings.clusterLabels}
+									onChange={(e) => changeSettings((cur) => ({ ...cur, clusterLabels: e.target.checked }))}
+									className="accent-primary"
+								/>
+							</label>
+							<SettingSlider
+								label="Cluster label size"
+								min={0}
+								max={100}
+								step={5}
+								value={toSliderPosition(settings.clusterLabelSize, CLUSTER_LABEL_SIZE_RANGE.min, CLUSTER_LABEL_SIZE_RANGE.max)}
+								display={sizeDisplay(settings.clusterLabelSize)}
+								onChange={(p) =>
+									changeSettings((cur) => ({
+										...cur,
+										clusterLabelSize: fromSliderPosition(p, CLUSTER_LABEL_SIZE_RANGE.min, CLUSTER_LABEL_SIZE_RANGE.max),
+									}))}
+							/>
 						</div>
 						{/* Physics: the live sim's forces. Every value feeds the SAME
 						    engine the server settle runs (createGraphSimulation);

src/core/render-settings.ts

@@ -34,6 +34,10 @@ export interface GraphRenderSettings {
 	labelSize: number;
 	/** Toggle for the cluster region labels (hulls always draw). */
 	clusterLabels: boolean;
+	/** Cluster label font size, px on screen (camera-compensated —
+	 *  constant at any zoom, unlike labelSize which scales with the
+	 *  graph). Defaults to the old REGION_LABEL_SIZE constant (14). */
+	clusterLabelSize: number;
 	/** Region rendering (the blurred cluster tints). Server-persisted
 	 *  since 2026-09-13 (user request) — was session-only dev state. */
 	regions: RegionTuning;
@@ -65,6 +69,12 @@ export function sanitizeRenderSettings(raw: unknown): GraphRenderSettings {
 		labelSize: num(r.labelSize, DEFAULT_RENDER_SETTINGS.labelSize, LABEL_SIZE_RANGE.min, LABEL_SIZE_RANGE.max),
 		clusterLabels:
 			typeof r.clusterLabels === "boolean" ? r.clusterLabels : DEFAULT_RENDER_SETTINGS.clusterLabels,
+		clusterLabelSize: num(
+			r.clusterLabelSize,
+			DEFAULT_RENDER_SETTINGS.clusterLabelSize,
+			CLUSTER_LABEL_SIZE_RANGE.min,
+			CLUSTER_LABEL_SIZE_RANGE.max,
+		),
 		// Nested sections (2026-09-13): old files lack them → defaults.
 		regions: sanitizeRegionTuning(r.regions),
 		physics: sanitizePhysicsTuning(r.physics),
@@ -214,6 +224,7 @@ export const DEFAULT_RENDER_SETTINGS: GraphRenderSettings = {
 	labelZoom: 0.5,
 	labelSize: 2,
 	clusterLabels: true,
+	clusterLabelSize: 14,
 	regions: DEFAULT_REGION_TUNING,
 	physics: DEFAULT_PHYSICS_TUNING,
 };
@@ -229,6 +240,9 @@ export const NODE_SIZE_RANGE = { min: 0.5, max: 8 } as const;
 export const EDGE_WIDTH_RANGE = { min: 0.25, max: 4 } as const;
 export const ARROW_LENGTH_RANGE = { min: 0.5, max: 8 } as const;
 export const LABEL_SIZE_RANGE = { min: 0.5, max: 8 } as const;
+// Screen-px at ANY zoom (drawn at size / k). 14 = geometric mean — old
+// REGION_LABEL_SIZE default, so the panel slider starts dead-center.
+export const CLUSTER_LABEL_SIZE_RANGE = { min: 7, max: 28 } as const;
 export const LABEL_ZOOM_MIN = 0.0625; // slider far left: labels only very deep in
 export const LABEL_ZOOM_MAX = 4; // slider far right: labels visible at fit zoom
 

tests/render-settings.test.ts

@@ -10,6 +10,7 @@ import { describe, it as test } from "node:test";
 import {
 	ARROW_LENGTH_RANGE,
 	CHARGE_RANGE,
+	CLUSTER_LABEL_SIZE_RANGE,
 	CLUSTER_PULL_RANGE,
 	DEFAULT_RENDER_SETTINGS,
 	DEPTH_BASE_RADIUS_RANGE,
@@ -53,6 +54,7 @@ describe("sanitizeRenderSettings", () => {
 		assert.equal(s.labelSize, DEFAULT_RENDER_SETTINGS.labelSize);
 		assert.equal(s.labelZoom, DEFAULT_RENDER_SETTINGS.labelZoom);
 		assert.equal(s.clusterLabels, DEFAULT_RENDER_SETTINGS.clusterLabels);
+		assert.equal(s.clusterLabelSize, DEFAULT_RENDER_SETTINGS.clusterLabelSize); // old files → 14
 	});
 
 	test("out-of-range values clamp; wrong types reset", () => {
@@ -63,6 +65,7 @@ describe("sanitizeRenderSettings", () => {
 			labelZoom: 100,
 			labelSize: "big" as unknown as number,
 			clusterLabels: "yes" as unknown as boolean,
+			clusterLabelSize: "huge" as unknown as number,
 		});
 		assert.equal(s.nodeSize, NODE_SIZE_RANGE.max); // clamped to max
 		assert.equal(s.edgeWidth, EDGE_WIDTH_RANGE.min); // clamped to min
@@ -70,6 +73,19 @@ describe("sanitizeRenderSettings", () => {
 		assert.equal(s.labelZoom, LABEL_ZOOM_MAX);
 		assert.equal(s.labelSize, DEFAULT_RENDER_SETTINGS.labelSize); // NaN-safe reset
 		assert.equal(s.clusterLabels, DEFAULT_RENDER_SETTINGS.clusterLabels);
+		assert.equal(s.clusterLabelSize, DEFAULT_RENDER_SETTINGS.clusterLabelSize); // NaN-safe reset
+	});
+
+	test("clusterLabelSize clamps to its own range (slider law)", () => {
+		// Default 14 is the geometric mean of [7, 28] → dead-center slider.
+		assert.equal(
+			Math.sqrt(CLUSTER_LABEL_SIZE_RANGE.min * CLUSTER_LABEL_SIZE_RANGE.max),
+			DEFAULT_RENDER_SETTINGS.clusterLabelSize,
+		);
+		const s = sanitizeRenderSettings({ clusterLabelSize: 999 });
+		assert.equal(s.clusterLabelSize, CLUSTER_LABEL_SIZE_RANGE.max);
+		const s2 = sanitizeRenderSettings({ clusterLabelSize: 1 });
+		assert.equal(s2.clusterLabelSize, CLUSTER_LABEL_SIZE_RANGE.min);
 	});
 
 	test("the low ends accept small sizes (log-slider floors)", () => {
@@ -88,6 +104,7 @@ describe("sanitizeRenderSettings", () => {
 			labelZoom: 0.25,
 			labelSize: 4,
 			clusterLabels: false,
+			clusterLabelSize: 20,
 			regions: DEFAULT_REGION_TUNING,
 			physics: DEFAULT_PHYSICS_TUNING,
 		};