diff --git a/packages/drawtonomy-sdk/__tests__/nodeEsmResolution.test.ts b/packages/drawtonomy-sdk/__tests__/nodeEsmResolution.test.ts
new file mode 100644
index 0000000..01faaa9
--- /dev/null
+++ b/packages/drawtonomy-sdk/__tests__/nodeEsmResolution.test.ts
@@ -0,0 +1,46 @@
+import { describe, it, expect } from 'vitest'
+import { execFileSync } from 'node:child_process'
+import { existsSync } from 'node:fs'
+import { fileURLToPath } from 'node:url'
+import { dirname, resolve } from 'node:path'
+
+/**
+ * Guards that the published build is importable by plain Node.js, not only by bundlers.
+ *
+ * The build previously emitted extensionless relative imports (`from './types'`), which
+ * bundlers resolve but Node's ESM loader rejects with ERR_MODULE_NOT_FOUND. Since the
+ * package ships `"type": "module"` and is documented for headless tooling, that made
+ * every `node script.mjs` usage fail while the bundled test suite stayed green.
+ *
+ * This test spawns a real Node process against `dist/`, so it fails if the emitted
+ * specifiers regress — something an in-process (Vite-transformed) test cannot catch.
+ */
+describe('published build resolves under plain Node ESM', () => {
+  const distEntry = resolve(dirname(fileURLToPath(import.meta.url)), '../dist/index.js')
+
+  it.skipIf(!existsSync(distEntry))('imports and runs a full generate + export cycle', () => {
+    const script = `
+      import * as sdk from ${JSON.stringify(distEntry)}
+      const lane = sdk.createLaneWithBoundaries(
+        [{ x: 0, y: 0 }, { x: 500, y: 0 }],
+        [{ x: 0, y: 50 }, { x: 500, y: 50 }],
+      )
+      const snapshot = sdk.createSnapshot([...lane, sdk.createVehicle({ x: 100, y: 25 })])
+      const xodr = sdk.exporter.exportToOpenDrive(snapshot, {})
+      const reparsed = sdk.exporter.odrToShapes(sdk.exporter.parseOpenDriveXml(xodr))
+      console.log(JSON.stringify({
+        exports: Object.keys(sdk).length,
+        roads: (xodr.match(/<road /g) || []).length,
+        lanesAfterRoundTrip: reparsed.lanes.length,
+      }))
+    `
+    const stdout = execFileSync(process.execPath, ['--input-type=module', '-e', script], {
+      encoding: 'utf8',
+    })
+    const result = JSON.parse(stdout.trim().split('\n').pop() as string)
+
+    expect(result.exports).toBeGreaterThan(0)
+    expect(result.roads).toBe(1)
+    expect(result.lanesAfterRoundTrip).toBe(1)
+  })
+})
diff --git a/packages/drawtonomy-sdk/src/ExtensionClient.ts b/packages/drawtonomy-sdk/src/ExtensionClient.ts
index 2a2ea14..5d0f79f 100644
--- a/packages/drawtonomy-sdk/src/ExtensionClient.ts
+++ b/packages/drawtonomy-sdk/src/ExtensionClient.ts
@@ -6,7 +6,7 @@ import type {
   DrawtonomySnapshot,
   ExportFormat,
   ExportResponse,
-} from './types'
+} from './types.js'
 
 interface PendingRequest {
   resolve: (value: unknown) => void
diff --git a/packages/drawtonomy-sdk/src/exporter/index.ts b/packages/drawtonomy-sdk/src/exporter/index.ts
index 43fd575..2ccf90b 100644
--- a/packages/drawtonomy-sdk/src/exporter/index.ts
+++ b/packages/drawtonomy-sdk/src/exporter/index.ts
@@ -7,37 +7,37 @@
 // turns OSM XML back into editor-ready primitives (points / linestrings /
 // lanes), enabling round-trip workflows.
 
-export { exportToOpenDrive, type OpenDriveExportOptions } from './opendrive'
+export { exportToOpenDrive, type OpenDriveExportOptions } from './opendrive.js'
 export {
   latLonToTmercProj,
   latLonToUtmProj,
   originToProjString,
   FALLBACK_GEO_REFERENCE,
   type GeoOrigin,
-} from './projection'
+} from './projection.js'
 export {
   exportToOpenScenario,
   templateIdToVehicleCategory,
   type OpenScenarioExportOptions,
   type TemplateResolver,
-} from './openscenario'
+} from './openscenario.js'
 export {
   buildPathTrajectory,
   DEFAULT_PATH_SPEED_MPS,
   type PathSamplePoint,
   type PathTrajectoryInput,
-} from './trajectory'
+} from './trajectory.js'
 export {
   computeCenterlineWithWidth,
   sampleAtParam,
   computeHeadings,
   type Point2D,
   type CenterlineSample,
-} from './laneCenterline'
-export { buildEsminiZip, type EsminiPackageOptions, type EsminiPackageResult } from './packageEsmini'
-export { buildZip, type ZipEntry } from './zip'
-export { sanitizeFileBaseName } from './sanitize'
-export { PIXELS_PER_METER } from './units'
+} from './laneCenterline.js'
+export { buildEsminiZip, type EsminiPackageOptions, type EsminiPackageResult } from './packageEsmini.js'
+export { buildZip, type ZipEntry } from './zip.js'
+export { sanitizeFileBaseName } from './sanitize.js'
+export { PIXELS_PER_METER } from './units.js'
 export {
   exportToLanelet2,
   trafficSignCode,
@@ -47,7 +47,7 @@ export {
   type Lanelet2ExportOptions,
   type OsmSidecar,
   type MapOrigin,
-} from './lanelet2'
+} from './lanelet2.js'
 export {
   parseOsmXml,
   latLonToCanvas,
@@ -56,7 +56,7 @@ export {
   type OsmNode,
   type OsmWay,
   type OsmRelation,
-} from './osmParser'
+} from './osmParser.js'
 export {
   osmToShapes,
   alignBoundaries,
@@ -71,7 +71,7 @@ export {
   type ImportBounds,
   type OsmToShapesOptions,
   type ShapeIdAllocator,
-} from './osmToShapes'
+} from './osmToShapes.js'
 export {
   parseOpenDriveXml,
   type OdrMap,
@@ -93,7 +93,7 @@ export {
   type OdrJunctionLaneLink,
   type OdrCubic,
   type OdrElevation,
-} from './opendriveParser'
+} from './opendriveParser.js'
 export {
   evalElevation,
   evalGeometry,
@@ -103,14 +103,14 @@ export {
   type GeomPose,
   type ReferenceSample,
   type SampleReferenceLineOptions,
-} from './odrGeometry'
+} from './odrGeometry.js'
 export {
   evalElevationRecords,
   fitElevationProfile,
   type ElevationRecord,
   type ElevationSample,
   type FitElevationOptions,
-} from './odrElevationFit'
+} from './odrElevationFit.js'
 export {
   odrToShapes,
   parseGeoReferenceOrigin,
@@ -118,4 +118,4 @@ export {
   type OdrRoadRecord,
   type OdrSidecar,
   type OdrToShapesOptions,
-} from './odrToShapes'
+} from './odrToShapes.js'
diff --git a/packages/drawtonomy-sdk/src/exporter/lanelet2.ts b/packages/drawtonomy-sdk/src/exporter/lanelet2.ts
index 6aa4e5f..eb97dd1 100644
--- a/packages/drawtonomy-sdk/src/exporter/lanelet2.ts
+++ b/packages/drawtonomy-sdk/src/exporter/lanelet2.ts
@@ -42,8 +42,8 @@ import type {
   PointProps,
   TrafficLightProps,
   TrafficSignProps,
-} from '../types'
-import { canvasToLatLon, parseOsmXml, type OsmData } from './osmParser'
+} from '../types.js'
+import { canvasToLatLon, parseOsmXml, type OsmData } from './osmParser.js'
 
 type LaneShape = BaseShape<'lane', LaneProps>
 type LinestringShape = BaseShape<'linestring', LinestringProps>
diff --git a/packages/drawtonomy-sdk/src/exporter/odrCarryThrough.ts b/packages/drawtonomy-sdk/src/exporter/odrCarryThrough.ts
index 899a46e..436140f 100644
--- a/packages/drawtonomy-sdk/src/exporter/odrCarryThrough.ts
+++ b/packages/drawtonomy-sdk/src/exporter/odrCarryThrough.ts
@@ -24,7 +24,7 @@
 //    collision-free, and rewrite only the link elementIds that must point at
 //    regenerated roads — leaving every other byte untouched.
 
-import type { Point2D } from './laneCenterline'
+import type { Point2D } from './laneCenterline.js'
 
 /** Per-road record captured at import time (stored in the sidecar). */
 export interface OdrRoadRecord {
diff --git a/packages/drawtonomy-sdk/src/exporter/odrGeometry.ts b/packages/drawtonomy-sdk/src/exporter/odrGeometry.ts
index 8a699dc..74e5441 100644
--- a/packages/drawtonomy-sdk/src/exporter/odrGeometry.ts
+++ b/packages/drawtonomy-sdk/src/exporter/odrGeometry.ts
@@ -8,7 +8,7 @@
 //
 // No external dependencies.
 
-import type { OdrCubic, OdrGeometry, OdrRoad } from './opendriveParser'
+import type { OdrCubic, OdrGeometry, OdrRoad } from './opendriveParser.js'
 
 /** Pose on the reference line: inertial position + heading. */
 export interface GeomPose {
diff --git a/packages/drawtonomy-sdk/src/exporter/odrGeometryFit.ts b/packages/drawtonomy-sdk/src/exporter/odrGeometryFit.ts
index 2625c6e..7c643a2 100644
--- a/packages/drawtonomy-sdk/src/exporter/odrGeometryFit.ts
+++ b/packages/drawtonomy-sdk/src/exporter/odrGeometryFit.ts
@@ -26,8 +26,8 @@
 //
 // No external dependencies.
 
-import type { OdrGeometry } from './opendriveParser'
-import { evalGeometry, type GeomPose } from './odrGeometry'
+import type { OdrGeometry } from './opendriveParser.js'
+import { evalGeometry, type GeomPose } from './odrGeometry.js'
 
 export interface FitPoint {
   x: number
diff --git a/packages/drawtonomy-sdk/src/exporter/odrToShapes.ts b/packages/drawtonomy-sdk/src/exporter/odrToShapes.ts
index 1931b77..f2abf60 100644
--- a/packages/drawtonomy-sdk/src/exporter/odrToShapes.ts
+++ b/packages/drawtonomy-sdk/src/exporter/odrToShapes.ts
@@ -36,9 +36,9 @@ import type {
   OdrRoad,
   OdrRoadMark,
   OdrSignalValidity,
-} from './opendriveParser'
-import { evalPoly3, sampleReferenceLine, type ReferenceSample } from './odrGeometry'
-import { sampleAtParam, type Point2D } from './laneCenterline'
+} from './opendriveParser.js'
+import { evalPoly3, sampleReferenceLine, type ReferenceSample } from './odrGeometry.js'
+import { sampleAtParam, type Point2D } from './laneCenterline.js'
 import {
   createShapeIdAllocator,
   type ImportBounds,
@@ -51,16 +51,16 @@ import {
   type ImportedTrafficLight,
   type ImportedTrafficSign,
   type ShapeIdAllocator,
-} from './osmToShapes'
-import { PIXELS_PER_METER } from './units'
+} from './osmToShapes.js'
+import { PIXELS_PER_METER } from './units.js'
 import {
   hashRoadState,
   type CarryLaneState,
   type CarryRegulatoryState,
   type OdrRoadRecord,
-} from './odrCarryThrough'
+} from './odrCarryThrough.js'
 
-export type { OdrRoadRecord } from './odrCarryThrough'
+export type { OdrRoadRecord } from './odrCarryThrough.js'
 
 /** Sidecar captured at OpenDRIVE import time (for verbatim round-trip export). */
 export interface OdrSidecar {
diff --git a/packages/drawtonomy-sdk/src/exporter/opendrive.ts b/packages/drawtonomy-sdk/src/exporter/opendrive.ts
index 26f887d..1f8f273 100644
--- a/packages/drawtonomy-sdk/src/exporter/opendrive.ts
+++ b/packages/drawtonomy-sdk/src/exporter/opendrive.ts
@@ -32,14 +32,14 @@ import type {
   PolygonProps,
   TrafficLightProps,
   TrafficSignProps,
-} from '../types'
-import { sampleAtParam, type Point2D } from './laneCenterline'
-import { evalGeometry } from './odrGeometry'
-import { fitPlanView, type FittedSamplePose } from './odrGeometryFit'
-import { fitElevationProfile, type ElevationSample } from './odrElevationFit'
-import type { OdrGeometry } from './opendriveParser'
-import { originToProjString } from './projection'
-import { escapeXml, fmt, fmtPrecise, pxToEnuX, pxToEnuY, pxToMeter } from './units'
+} from '../types.js'
+import { sampleAtParam, type Point2D } from './laneCenterline.js'
+import { evalGeometry } from './odrGeometry.js'
+import { fitPlanView, type FittedSamplePose } from './odrGeometryFit.js'
+import { fitElevationProfile, type ElevationSample } from './odrElevationFit.js'
+import type { OdrGeometry } from './opendriveParser.js'
+import { originToProjString } from './projection.js'
+import { escapeXml, fmt, fmtPrecise, pxToEnuX, pxToEnuY, pxToMeter } from './units.js'
 import {
   appendControlRecords,
   dropControlRecords,
@@ -51,9 +51,9 @@ import {
   type OdrDocRoad,
   type OdrDocument,
   type OdrRoadRecord,
-} from './odrCarryThrough'
-import type { OdrSidecar } from './odrToShapes'
-import { trafficSignCode } from './lanelet2'
+} from './odrCarryThrough.js'
+import type { OdrSidecar } from './odrToShapes.js'
+import { trafficSignCode } from './lanelet2.js'
 
 type LaneShape = BaseShape<'lane', LaneProps>
 type LinestringShape = BaseShape<'linestring', LinestringProps>
diff --git a/packages/drawtonomy-sdk/src/exporter/openscenario.ts b/packages/drawtonomy-sdk/src/exporter/openscenario.ts
index a519895..0e80184 100644
--- a/packages/drawtonomy-sdk/src/exporter/openscenario.ts
+++ b/packages/drawtonomy-sdk/src/exporter/openscenario.ts
@@ -14,9 +14,9 @@ import type {
   LinestringProps,
   PointProps,
   VehicleProps,
-} from '../types'
-import { buildPathTrajectory, type PathSamplePoint } from './trajectory'
-import { escapeXml, fmt, pxToEnuX, pxToEnuY, pxToMeter } from './units'
+} from '../types.js'
+import { buildPathTrajectory, type PathSamplePoint } from './trajectory.js'
+import { escapeXml, fmt, pxToEnuX, pxToEnuY, pxToMeter } from './units.js'
 
 type VehicleShape = BaseShape<'vehicle', VehicleProps>
 type LinestringShape = BaseShape<'linestring', LinestringProps>
diff --git a/packages/drawtonomy-sdk/src/exporter/osmToShapes.ts b/packages/drawtonomy-sdk/src/exporter/osmToShapes.ts
index 5370b5b..c3c47f8 100644
--- a/packages/drawtonomy-sdk/src/exporter/osmToShapes.ts
+++ b/packages/drawtonomy-sdk/src/exporter/osmToShapes.ts
@@ -9,8 +9,8 @@
 // alignment, progress reporting, etc.). Callers can wrap the result into
 // shapes themselves.
 
-import type { ShapeId } from '../types'
-import { latLonToCanvas, type OsmData } from './osmParser'
+import type { ShapeId } from '../types.js'
+import { latLonToCanvas, type OsmData } from './osmParser.js'
 
 /**
  * ID allocator interface. The default implementation produces predictable
diff --git a/packages/drawtonomy-sdk/src/exporter/packageEsmini.ts b/packages/drawtonomy-sdk/src/exporter/packageEsmini.ts
index 88c923a..43c6629 100644
--- a/packages/drawtonomy-sdk/src/exporter/packageEsmini.ts
+++ b/packages/drawtonomy-sdk/src/exporter/packageEsmini.ts
@@ -3,11 +3,11 @@
 // `<baseName>/<baseName>.xosc`. The xosc <LogicFile> reference uses the same
 // baseName so the bundle works without renames.
 
-import type { DrawtonomySnapshot } from '../types'
-import { exportToOpenDrive } from './opendrive'
-import { exportToOpenScenario, type TemplateResolver } from './openscenario'
-import { sanitizeFileBaseName } from './sanitize'
-import { buildZip } from './zip'
+import type { DrawtonomySnapshot } from '../types.js'
+import { exportToOpenDrive } from './opendrive.js'
+import { exportToOpenScenario, type TemplateResolver } from './openscenario.js'
+import { sanitizeFileBaseName } from './sanitize.js'
+import { buildZip } from './zip.js'
 
 export interface EsminiPackageOptions {
   /**
diff --git a/packages/drawtonomy-sdk/src/exporter/trajectory.ts b/packages/drawtonomy-sdk/src/exporter/trajectory.ts
index 168f377..147a236 100644
--- a/packages/drawtonomy-sdk/src/exporter/trajectory.ts
+++ b/packages/drawtonomy-sdk/src/exporter/trajectory.ts
@@ -23,7 +23,7 @@
 //
 // Default speed: 10 m/s (≈ 36 km/h, residential).
 
-import { PIXELS_PER_METER } from './units'
+import { PIXELS_PER_METER } from './units.js'
 
 export interface PathSamplePoint {
   /** ENU x (m) */
diff --git a/packages/drawtonomy-sdk/src/helpers.ts b/packages/drawtonomy-sdk/src/helpers.ts
index a45467c..285a68d 100644
--- a/packages/drawtonomy-sdk/src/helpers.ts
+++ b/packages/drawtonomy-sdk/src/helpers.ts
@@ -10,8 +10,8 @@ import type {
   EllipseProps,
   TextProps,
   DrawtonomySnapshot,
-} from './types'
-import { evaluatePathAt, uniformTValues } from './geometry'
+} from './types.js'
+import { evaluatePathAt, uniformTValues } from './geometry.js'
 
 let idCounter = 0
 
diff --git a/packages/drawtonomy-sdk/src/index.ts b/packages/drawtonomy-sdk/src/index.ts
index 4282f70..425613f 100644
--- a/packages/drawtonomy-sdk/src/index.ts
+++ b/packages/drawtonomy-sdk/src/index.ts
@@ -1,8 +1,8 @@
 // @drawtonomy/sdk - Entry Point
-export * from './types'
-export * from './helpers'
-export * from './geometry'
-export { ExtensionClient } from './ExtensionClient'
-export { parseDrawtonomySvg } from './snapshot'
+export * from './types.js'
+export * from './helpers.js'
+export * from './geometry.js'
+export { ExtensionClient } from './ExtensionClient.js'
+export { parseDrawtonomySvg } from './snapshot.js'
 // Exporter sub-module is also available via "@drawtonomy/sdk/exporter".
-export * as exporter from './exporter'
+export * as exporter from './exporter/index.js'
diff --git a/packages/drawtonomy-sdk/src/snapshot.ts b/packages/drawtonomy-sdk/src/snapshot.ts
index 435d94c..b4e2ae5 100644
--- a/packages/drawtonomy-sdk/src/snapshot.ts
+++ b/packages/drawtonomy-sdk/src/snapshot.ts
@@ -3,7 +3,7 @@
 // DrawtonomySnapshot. The legacy attribute name `data-drawauto-snapshot`
 // is also accepted for backwards compatibility.
 
-import type { DrawtonomySnapshot } from './types'
+import type { DrawtonomySnapshot } from './types.js'
 
 /**
  * Decode a base64-encoded UTF-8 string. Mirrors the encoder used when the
diff --git a/packages/drawtonomy-sdk/tsconfig.json b/packages/drawtonomy-sdk/tsconfig.json
index f5b25e7..d299cdf 100644
--- a/packages/drawtonomy-sdk/tsconfig.json
+++ b/packages/drawtonomy-sdk/tsconfig.json
@@ -1,9 +1,12 @@
 {
   "compilerOptions": {
     "target": "ES2020",
-    "module": "ESNext",
-    "moduleResolution": "bundler",
-    "lib": ["ES2020", "DOM"],
+    "module": "NodeNext",
+    "moduleResolution": "nodenext",
+    "lib": [
+      "ES2020",
+      "DOM"
+    ],
     "declaration": true,
     "declarationMap": true,
     "sourceMap": true,
@@ -13,5 +16,7 @@
     "skipLibCheck": true,
     "isolatedModules": true
   },
-  "include": ["src"]
+  "include": [
+    "src"
+  ]
 }