diff --git a/server/src/nest/paddle-routing/engine/geo.ts b/server/src/lib/geo/geo.ts
similarity index 95%
rename from server/src/nest/paddle-routing/engine/geo.ts
rename to server/src/lib/geo/geo.ts
index 8b5f8d619..462d795d3 100644
--- a/server/src/nest/paddle-routing/engine/geo.ts
+++ b/server/src/lib/geo/geo.ts
@@ -1,4 +1,4 @@
-/** Metres per degree of latitude, the figure the paddle code reckons with throughout. */
+/** Metres per degree of latitude, the figure the routing code reckons with throughout. */
 const M_PER_DEG = 111_195;
 
 export function metresBetween(aLat: number, aLng: number, bLat: number, bLng: number): number {
diff --git a/server/src/nest/paddle-routing/engine/min-heap.ts b/server/src/lib/geo/min-heap.ts
similarity index 100%
rename from server/src/nest/paddle-routing/engine/min-heap.ts
rename to server/src/lib/geo/min-heap.ts
diff --git a/server/src/nest/paddle-routing/build/build-state.ts b/server/src/nest/paddle-routing/build/build-state.ts
index 4b327e037..542bcbefe 100644
--- a/server/src/nest/paddle-routing/build/build-state.ts
+++ b/server/src/nest/paddle-routing/build/build-state.ts
@@ -1,4 +1,4 @@
-import { lineLength, metresBetween, projectOnSegment } from '../engine/geo';
+import { lineLength, metresBetween, projectOnSegment } from '../../../lib/geo/geo';
 import { Access, EdgeKind, type EdgeKindCode, PortageSource } from '../water-graph';
 
 /** A node while the network is built: where it is, and the lake it opens into (-1 for none). */
diff --git a/server/src/nest/paddle-routing/build/lakes.ts b/server/src/nest/paddle-routing/build/lakes.ts
index da7c54580..202ffa4ce 100644
--- a/server/src/nest/paddle-routing/build/lakes.ts
+++ b/server/src/nest/paddle-routing/build/lakes.ts
@@ -1,4 +1,4 @@
-import { LocalFrame } from '../engine/geo';
+import { LocalFrame } from '../../../lib/geo/geo';
 import type { LakeGrid } from '../water-graph';
 import { type BuildEdge, type BuildState, PointGrid } from './build-state';
 import type { CollectedArea, CollectedWater } from './collect';
diff --git a/server/src/nest/paddle-routing/build/portages.ts b/server/src/nest/paddle-routing/build/portages.ts
index 0f60e7d1f..da98df080 100644
--- a/server/src/nest/paddle-routing/build/portages.ts
+++ b/server/src/nest/paddle-routing/build/portages.ts
@@ -1,4 +1,4 @@
-import { projectOnSegment } from '../engine/geo';
+import { projectOnSegment } from '../../../lib/geo/geo';
 import { Access, EdgeKind, PortageSource } from '../water-graph';
 import { type BarrierSite, type BuildEdge, type BuildState, PointGrid } from './build-state';
 import type { CollectedWater } from './collect';
diff --git a/server/src/nest/paddle-routing/engine/lake-field.ts b/server/src/nest/paddle-routing/engine/lake-field.ts
index 1576020a0..b854b4ed5 100644
--- a/server/src/nest/paddle-routing/engine/lake-field.ts
+++ b/server/src/nest/paddle-routing/engine/lake-field.ts
@@ -1,7 +1,7 @@
+import { LocalFrame } from '../../../lib/geo/geo';
+import { MinHeap } from '../../../lib/geo/min-heap';
 import { maskHas } from '../build/lakes';
 import type { LakeGrid } from '../water-graph';
-import { LocalFrame } from './geo';
-import { MinHeap } from './min-heap';
 import type { PaddleLakeStyle } from '@trek/shared';
 
 /**
diff --git a/server/src/nest/paddle-routing/engine/router.ts b/server/src/nest/paddle-routing/engine/router.ts
index fb7d9e30f..515280a5f 100644
--- a/server/src/nest/paddle-routing/engine/router.ts
+++ b/server/src/nest/paddle-routing/engine/router.ts
@@ -1,8 +1,8 @@
+import { metresBetween, projectOnSegment } from '../../../lib/geo/geo';
+import { MinHeap } from '../../../lib/geo/min-heap';
 import { LakeIndex } from '../build/lakes';
 import { Access, EdgeKind, PortageSource, type WaterGraphData } from '../water-graph';
-import { metresBetween, projectOnSegment } from './geo';
 import { LakeField, type LakeProfile } from './lake-field';
-import { MinHeap } from './min-heap';
 import type {
   PaddleBoatType,
   PaddleLakeStyle,