diff --git a/font-src/gen/caching/index.js b/font-src/gen/caching/index.js
index 7891754a3..62da13a87 100644
--- a/font-src/gen/caching/index.js
+++ b/font-src/gen/caching/index.js
@@ -4,7 +4,7 @@ const fs = require("fs-extra");
 const zlib = require("zlib");
 const { encode, decode } = require("@msgpack/msgpack");
 
-const Edition = 7;
+const Edition = 8;
 const MAX_AGE = 5;
 
 class GfEntry {
diff --git a/font-src/kits/spiro-kit.ptl b/font-src/kits/spiro-kit.ptl
index 96dbd6051..58c1d0ea8 100644
--- a/font-src/kits/spiro-kit.ptl
+++ b/font-src/kits/spiro-kit.ptl
@@ -1,8 +1,9 @@
 import 'spiro' as SpiroJs
-import [SpiroExpansionContext1 SpiroExpansionContext2] from '../support/spiro-expand'
 import '../support/curve-util' as CurveUtil
 import '../support/transform' as Transform
-import '../support/utils' as [object fallback mix bez2 bez3]
+import [SpiroExpansionContext1 SpiroExpansionContext2] from '../support/spiro-expand'
+import [fallback mix bez2 bez3] from '../support/utils'
+import [SpiroGeometry CombineGeometry] from "../support/geometry"
 
 export : define [SetupBuilders args] : begin
 	define [object para Glyph Contrast GlobalTransform Stroke] args
@@ -182,9 +183,6 @@ export : define [SetupBuilders args] : begin
 		set knots : flatten s knots
 		return { .knots knots .closed closed }
 
-	define [convertSpiroToBezier knots closed ctx] : begin
-		return : SpiroJs.spiroToBezierOnContext knots closed ctx CurveUtil.SPIRO_PRECISION
-
 	define [iterateNormals s closed] : begin
 		local knotsP2 : s.getPass2Knots closed [fallback s.contrast Contrast]
 		local s2 : new SpiroExpansionContext2 s.controlKnots s.gizmo
@@ -205,30 +203,23 @@ export : define [SetupBuilders args] : begin
 		local {.lhs lhs .rhs rhs} : s.expand [fallback s.contrast Contrast]
 
 		if closed : then
-			local g : new CurveUtil.BezToContoursSink
-			# CurveUtil.BezToContoursSink::beginShape won't clear the contours
-			# We will get two contours at last
-			convertSpiroToBezier [lhs.slice 0 (-1)] CLOSED g
-			convertSpiroToBezier [rhs.reverse :.slice 0 (-1)] CLOSED g
-			set g.contours { [g.contours.0.concat g.contours.1] }
+			this.includeGeometry : new CombineGeometry : list
+				new SpiroGeometry [lhs.slice 0 (-1)]           closed [Transform.Id]
+				new SpiroGeometry [rhs.reverse :.slice 0 (-1)] closed [Transform.Id]
+
 		: else : begin
-			local g : new CurveUtil.BezToContoursSink
 			lhs.0.type = lhs.(lhs.length - 1).type = 'corner'
 			rhs.0.type = rhs.(rhs.length - 1).type = 'corner'
-			convertSpiroToBezier [lhs.concat : rhs.reverse] CLOSED g
+			define allKnots : lhs.concat : rhs.reverse
+			this.includeGeometry : new SpiroGeometry allKnots CLOSED [Transform.Id]
 
-		set g.knots knots
-		set g.lhsKnots lhs
-		set g.rhsKnots rhs
-		this.includeContours g.contours 0 0
-		return g
+		return { .knots knots .lhsKnots lhs .rhsKnots rhs }
 
 	define [spiro-outline] : let [k : {}.slice.call arguments 0] : lambda [] : begin
-		local g : new CurveUtil.BezToContoursSink (this.gizmo || GlobalTransform)
+		local gizmo : this.gizmo || GlobalTransform
+		local g : new CurveUtil.BezToContoursSink gizmo
 		local { .knots knots .closed closed } : prepareSpiroKnots k g
-		convertSpiroToBezier knots closed g
-		this.includeContours g.contours 0 0
-		return g
+		this.includeGeometry : new SpiroGeometry knots closed gizmo
 
 	return [object
 		g4 g2 corner flat curl close end straight
diff --git a/font-src/support/geometry.js b/font-src/support/geometry.js
index 609531b7c..5a394ef17 100644
--- a/font-src/support/geometry.js
+++ b/font-src/support/geometry.js
@@ -2,6 +2,7 @@
 
 const crypto = require("crypto");
 const TypoGeom = require("typo-geom");
+const SpiroJs = require("spiro");
 
 const Point = require("./point");
 const Transform = require("./transform");
@@ -70,6 +71,55 @@ class ContourGeometry extends GeometryBase {
 	}
 }
 
+class SpiroGeometry extends GeometryBase {
+	constructor(knots, closed, gizmo) {
+		super();
+		this.m_knots = [];
+		for (const k of knots) {
+			this.m_knots.push({ type: k.type, x: k.x, y: k.y });
+		}
+		this.m_closed = closed;
+		this.m_gizmo = gizmo;
+		this.m_cachedContours = null;
+	}
+	asContours() {
+		if (this.m_cachedContours) return this.m_cachedContours;
+		const s = new CurveUtil.BezToContoursSink(this.m_gizmo);
+		SpiroJs.spiroToBezierOnContext(this.m_knots, this.m_closed, s, CurveUtil.SPIRO_PRECISION);
+		this.m_cachedContours = s.contours;
+		return this.m_cachedContours;
+	}
+	asReferences() {
+		return null;
+	}
+	filterTag(fn) {
+		return this;
+	}
+	isEmpty() {
+		return !this.m_knots.length;
+	}
+	measureComplexity() {
+		for (const z of this.m_knots) {
+			if (!isFinite(z.x) || !isFinite(z.y)) return 0xffff;
+		}
+		return this.m_knots.length;
+	}
+	toShapeStringOrNull() {
+		let s = "SpiroGeometry{{";
+		for (const k of this.m_knots) {
+			s += `(${k.type};${formatN(k.x)};${formatN(k.y)})`;
+		}
+		s += "};";
+		s += `${this.m_closed};`;
+		s +=
+			`;{${formatN(this.m_gizmo.xx)},${formatN(this.m_gizmo.xy)},` +
+			`${formatN(this.m_gizmo.yx)},${formatN(this.m_gizmo.yy)},` +
+			`${formatN(this.m_gizmo.x)},${formatN(this.m_gizmo.y)}}`;
+		s += "}";
+		return s;
+	}
+}
+
 class ReferenceGeometry extends GeometryBase {
 	constructor(glyph, x, y) {
 		super();
@@ -380,6 +430,7 @@ function formatN(x) {
 }
 
 exports.GeometryBase = GeometryBase;
+exports.SpiroGeometry = SpiroGeometry;
 exports.ContourGeometry = ContourGeometry;
 exports.ReferenceGeometry = ReferenceGeometry;
 exports.TaggedGeometry = TaggedGeometry;