diff --git a/frontend/src/lib/person/genealogy/panZoom.test.ts b/frontend/src/lib/person/genealogy/panZoom.test.ts
index ad9e8371..e881f6a4 100644
--- a/frontend/src/lib/person/genealogy/panZoom.test.ts
+++ b/frontend/src/lib/person/genealogy/panZoom.test.ts
@@ -31,13 +31,13 @@ describe('clampZoom', () => {
 	});
 
 	it('clamps above MAX_ZOOM down to MAX_ZOOM', () => {
-		expect(clampZoom(5)).toBe(MAX_ZOOM);
-		expect(clampZoom(3.0001)).toBe(MAX_ZOOM);
+		expect(clampZoom(99)).toBe(MAX_ZOOM);
+		expect(clampZoom(MAX_ZOOM + 0.0001)).toBe(MAX_ZOOM);
 	});
 
 	it('exposes the resolved zoom bounds', () => {
 		expect(MIN_ZOOM).toBe(0.25);
-		expect(MAX_ZOOM).toBe(3.0);
+		expect(MAX_ZOOM).toBe(10);
 	});
 });
 
diff --git a/frontend/src/lib/person/genealogy/panZoom.ts b/frontend/src/lib/person/genealogy/panZoom.ts
index 69c4af40..b306d095 100644
--- a/frontend/src/lib/person/genealogy/panZoom.ts
+++ b/frontend/src/lib/person/genealogy/panZoom.ts
@@ -9,9 +9,14 @@
  * project. See ADR-027 for why this is custom rather than a third-party library.
  */
 
-/** Resolved zoom bounds (OQ-001). */
+/**
+ * Zoom bounds. OQ-001 originally resolved the ceiling to 3.0, but because zoom
+ * is normalised to the whole tree, z=3 still shows too much of a wide tree to be
+ * legible on a phone — so the ceiling was raised to 10 (product-owner revision,
+ * #692). SVG stays vector-crisp at any zoom, so a generous max is harmless.
+ */
 export const MIN_ZOOM = 0.25;
-export const MAX_ZOOM = 3.0;
+export const MAX_ZOOM = 10;
 export const DEFAULT_ZOOM = 1;
 
 /** Minimum zoom a recentre will snap up to so the focal node's text is legible (OQ-005). */