diff --git a/ui/frontend/src/lib/active-view/map.svelte b/ui/frontend/src/lib/active-view/map.svelte
index 8b60519..35f1255 100644
--- a/ui/frontend/src/lib/active-view/map.svelte
+++ b/ui/frontend/src/lib/active-view/map.svelte
@@ -117,6 +117,50 @@ preference the store already manages.
 	let containerEl: HTMLDivElement | null = $state(null);
 	let mountError: string | null = $state(null);
 
+	// F8-12 follow-up: an opt-in technical overlay activated by adding
+	// `?debug=1` to the URL. Shows the current camera scale and the
+	// world-units rectangle currently visible inside the viewport — so
+	// the owner can decide what to clamp `maxScale` to once it lands.
+	const debugOverlayEnabled = (() => {
+		if (typeof window === "undefined") return false;
+		return new URLSearchParams(window.location.search).get("debug") === "1";
+	})();
+	let debugInfo: {
+		scale: number;
+		scaleRef: number;
+		viewWorldWidth: number;
+		viewWorldHeight: number;
+	} | null = $state(null);
+	let debugFrame: number | null = null;
+	function startDebugLoop(): void {
+		if (!debugOverlayEnabled) return;
+		const tick = (): void => {
+			if (handle !== null) {
+				const camera = handle.getCamera();
+				const vp = handle.getViewport();
+				const safeScale = camera.scale > 0 ? camera.scale : 1;
+				const worldW = store?.report?.mapWidth ?? 1;
+				const worldH = store?.report?.mapHeight ?? 1;
+				debugInfo = {
+					scale: camera.scale,
+					scaleRef: Math.max(vp.widthPx / worldW, vp.heightPx / worldH),
+					viewWorldWidth: vp.widthPx / safeScale,
+					viewWorldHeight: vp.heightPx / safeScale,
+				};
+			} else {
+				debugInfo = null;
+			}
+			debugFrame = requestAnimationFrame(tick);
+		};
+		debugFrame = requestAnimationFrame(tick);
+	}
+	function stopDebugLoop(): void {
+		if (debugFrame !== null) {
+			cancelAnimationFrame(debugFrame);
+			debugFrame = null;
+		}
+	}
+
 	let handle: RendererHandle | null = null;
 	let hitLookup = new Map<PrimitiveID, HitTarget>();
 	// currentCategories / currentPlanetDependents are populated by
@@ -797,6 +841,7 @@ preference the store already manages.
 
 	onMount(() => {
 		mounted = true;
+		startDebugLoop();
 		onResize = (): void => {
 			if (handle === null || containerEl === null) return;
 			handle.resize(containerEl.clientWidth, containerEl.clientHeight);
@@ -814,6 +859,7 @@ preference the store already manages.
 
 	onDestroy(() => {
 		mounted = false;
+		stopDebugLoop();
 		if (onResize !== null) {
 			window.removeEventListener("resize", onResize);
 			onResize = null;
@@ -868,6 +914,30 @@ preference the store already manages.
 		{#if store !== undefined && store.status === "ready"}
 			<MapTogglesControl {store} />
 		{/if}
+		{#if debugOverlayEnabled && debugInfo !== null}
+			<div class="debug-overlay" data-testid="map-debug-overlay" aria-hidden="true">
+				<div class="debug-row">
+					<span class="debug-key">scale</span>
+					<span class="debug-val">{debugInfo.scale.toFixed(3)}</span>
+				</div>
+				<div class="debug-row">
+					<span class="debug-key">scale_ref</span>
+					<span class="debug-val">{debugInfo.scaleRef.toFixed(3)}</span>
+				</div>
+				<div class="debug-row">
+					<span class="debug-key">scale_ratio</span>
+					<span class="debug-val">
+						×{(debugInfo.scale / debugInfo.scaleRef).toFixed(2)}
+					</span>
+				</div>
+				<div class="debug-row">
+					<span class="debug-key">view W×H</span>
+					<span class="debug-val">
+						{debugInfo.viewWorldWidth.toFixed(1)} × {debugInfo.viewWorldHeight.toFixed(1)}
+					</span>
+				</div>
+			</div>
+		{/if}
 	</div>
 </section>
 
@@ -911,4 +981,32 @@ preference the store already manages.
 		border-color: var(--color-danger);
 		color: var(--color-danger);
 	}
+	.debug-overlay {
+		position: absolute;
+		bottom: 0.5rem;
+		left: 0.5rem;
+		min-width: 11rem;
+		padding: 0.35rem 0.55rem;
+		background: rgba(0, 0, 0, 0.55);
+		color: #f3f5fb;
+		border: 1px solid rgba(255, 255, 255, 0.2);
+		border-radius: 4px;
+		font-family: var(--font-mono, ui-monospace, SFMono-Regular, Menlo, monospace);
+		font-size: 0.72rem;
+		line-height: 1.25;
+		pointer-events: none;
+		user-select: none;
+		z-index: 5;
+	}
+	.debug-row {
+		display: flex;
+		justify-content: space-between;
+		gap: 0.5rem;
+	}
+	.debug-key {
+		color: rgba(243, 245, 251, 0.65);
+	}
+	.debug-val {
+		font-variant-numeric: tabular-nums;
+	}
 </style>
diff --git a/ui/frontend/src/map/render.ts b/ui/frontend/src/map/render.ts
index 0d50cff..b94138d 100644
--- a/ui/frontend/src/map/render.ts
+++ b/ui/frontend/src/map/render.ts
@@ -772,7 +772,7 @@ export async function createRenderer(opts: RendererOptions): Promise<RendererHan
 		const outlineRadius = visibleRadius + paddingWorld;
 		for (const g of entry.graphics) {
 			g.clear();
-			g.circle(planetPrim.x, planetPrim.y, outlineRadius);
+			traceSmoothCircle(g, planetPrim.x, planetPrim.y, outlineRadius);
 			g.stroke({
 				color: entry.spec.color,
 				alpha: 0.95,
@@ -1147,7 +1147,8 @@ export async function createRenderer(opts: RendererOptions): Promise<RendererHan
 				// paints in `pickHighlight` so the player sees the
 				// destination candidate just like a selection — only
 				// in the warm picker accent.
-				g.circle(
+				traceSmoothCircle(
+					g,
 					spec.hoverOutline.x,
 					spec.hoverOutline.y,
 					spec.hoverOutline.radius,
@@ -1520,6 +1521,35 @@ function rendererBackendName(r: Renderer): "webgl" | "webgpu" | "canvas" {
 	return "webgl";
 }
 
+/**
+ * SMOOTH_CIRCLE_SEGMENTS is the fixed segment count the renderer
+ * uses for every disc / ring. PixiJS v8's `Graphics.circle` picks
+ * the segment count from the world-space radius, which is fine for
+ * a fully-scaled scene but breaks the moment we draw the same disc
+ * at a small world radius inside a heavily-zoomed parent container:
+ * the planet renders as a visible 6-8-gon. Painting a fixed-density
+ * polygon ourselves keeps the silhouette round at every zoom level.
+ * 32 segments is the standard "perceptually round" budget; it stays
+ * cheap (~64 floats per disc) on a 500-planet map.
+ */
+const SMOOTH_CIRCLE_SEGMENTS = 32;
+
+function traceSmoothCircle(
+	g: Graphics,
+	x: number,
+	y: number,
+	radius: number,
+): void {
+	if (radius <= 0) return;
+	const step = (2 * Math.PI) / SMOOTH_CIRCLE_SEGMENTS;
+	g.moveTo(x + radius, y);
+	for (let i = 1; i < SMOOTH_CIRCLE_SEGMENTS; i++) {
+		const a = i * step;
+		g.lineTo(x + radius * Math.cos(a), y + radius * Math.sin(a));
+	}
+	g.closePath();
+}
+
 function drawPoint(
 	g: Graphics,
 	p: PointPrim,
@@ -1530,11 +1560,13 @@ function drawPoint(
 	const color = p.style.fillColor ?? theme.pointFill;
 	const alpha = p.style.fillAlpha ?? 1;
 	const radius = displayPointRadiusWorld(p.style, cameraScale, scaleRef);
-	g.circle(p.x, p.y, radius);
+	traceSmoothCircle(g, p.x, p.y, radius);
 	g.fill({ color, alpha });
 	if (p.style.strokeColor !== undefined && (p.style.strokeWidthPx ?? 0) > 0) {
 		const strokeAlpha = p.style.strokeAlpha ?? 1;
 		const strokeWidth = displayStrokeWidthWorld(p.style, cameraScale);
+		// Retrace because Pixi's `fill()` closes the current path.
+		traceSmoothCircle(g, p.x, p.y, radius);
 		g.stroke({
 			color: p.style.strokeColor,
 			alpha: strokeAlpha,
@@ -1549,9 +1581,14 @@ function drawCircle(
 	theme: Theme,
 	cameraScale: number,
 ): void {
-	g.circle(p.x, p.y, p.radius);
-	if (p.style.fillColor !== undefined) {
-		g.fill({ color: p.style.fillColor, alpha: p.style.fillAlpha ?? 1 });
+	const hasFill =
+		p.style.fillColor !== undefined && (p.style.fillAlpha ?? 1) > 0;
+	traceSmoothCircle(g, p.x, p.y, p.radius);
+	if (hasFill) {
+		g.fill({ color: p.style.fillColor!, alpha: p.style.fillAlpha ?? 1 });
+		// Pixi's `fill()` closes the current path — retrace before
+		// the stroke pass so the ring is actually painted on top.
+		traceSmoothCircle(g, p.x, p.y, p.radius);
 	}
 	const strokeColor = p.style.strokeColor ?? theme.circleStroke;
 	const strokeAlpha = p.style.strokeAlpha ?? 1;