perf: load the network from a single shared asset instead of inlining it in both builds

CHANGELOG.md

@@ -10,6 +10,12 @@
   as a CORS-enabled asset on the demo's GitHub Pages site
   (`/searoute-ts/marnet.json`).
 
+### Changed
+- The Eurostat network is no longer inlined into each build. It now ships once
+  as a single shared `dist/data/marnet.cjs` asset that both the CJS and ESM
+  builds load at runtime, roughly halving the published package size
+  (~329 KB → ~184 KB packed, ~2.5 MB → ~1.3 MB unpacked). No API change. (#10)
+
 ## 2.0.1 — 2026-07-02
 
 ### Fixed
@@ -128,9 +134,9 @@ see ~24% smaller numbers — they now match the geodesic length in nm correctly.
   (Shanghai-Rotterdam, NY-Rotterdam, Yokohama-LA, etc.) within ±10%.
 
 ### Known follow-ups
-- The marnet is inlined in the bundle (~1.1 MB per build, ~2.2 MB total
+- ~~The marnet is inlined in the bundle (~1.1 MB per build, ~2.2 MB total
   unpacked). Migrating to a single shared JSON asset is a non-breaking
-  follow-up and would roughly halve published size.
+  follow-up and would roughly halve published size.~~ Done in Unreleased (#10).
 - Multi-resolution networks (Eurostat ships 5 km / 10 km / 20 km / 50 km /
   100 km). Currently we only ship 100 km. Other resolutions could be loaded
   via a separate import path.

README.md

@@ -306,8 +306,10 @@ or AIS-derived custom graphs.
 marnet has been normalised so the Pacific is a connected graph, and all
 distances use haversine internally.
 
-**What's the bundle size?** 329 KB packed / 2.5 MB unpacked on npm. The
-bundled marnet is the bulk (~1.1 MB JSON per build). Tree-shakeable.
+**What's the bundle size?** ~184 KB packed / ~1.3 MB unpacked on npm. The
+bundled marnet is the bulk (~1.1 MB JSON). It ships once as a shared
+`dist/data/marnet.cjs` asset that both the CJS and ESM builds load at runtime,
+rather than being inlined into each build. Tree-shakeable.
 
 ## Credits
 

data/marnet.d.cts

@@ -0,0 +1,7 @@
+import type { FeatureCollection, LineString } from 'geojson';
+
+/** Optional native passage label carried on marnet edges. */
+export type MarnetProperties = { pass?: string };
+
+declare const marnetData: FeatureCollection<LineString, MarnetProperties>;
+export default marnetData;

package.json

@@ -53,7 +53,7 @@
   ],
   "scripts": {
     "clean": "rm -rf dist build coverage",
-    "build": "npm run clean && npm run build:cjs && npm run build:esm && npm run build:types && node scripts/fixup-cjs.cjs",
+    "build": "npm run clean && npm run build:cjs && npm run build:esm && npm run build:types && node scripts/fixup-cjs.cjs && node scripts/copy-marnet.cjs dist",
     "build:cjs": "tsc -p tsconfig.cjs.json",
     "build:esm": "tsc -p tsconfig.esm.json",
     "build:types": "tsc -p tsconfig.types.json",
@@ -62,7 +62,7 @@
     "format:check": "prettier --check \"src/**/*.{ts,json}\"",
     "test": "npm run build:test && ava",
     "test:unit": "ava",
-    "build:test": "tsc -p tsconfig.test.json",
+    "build:test": "tsc -p tsconfig.test.json && node scripts/copy-marnet.cjs build",
     "prepublishOnly": "npm run lint && npm run test"
   },
   "engines": {

scripts/build-marnet.cjs

@@ -1,6 +1,9 @@
-/* Generate src/lib/marnet.ts from the eurostat marnet_plus_100km GeoJSON.
- * Embeds the data as a JSON string + JSON.parse() so the TypeScript compiler
- * doesn't pretty-print a 1 MB object literal into a 2.8 MB JS module.
+/* Generate data/marnet.cjs from the eurostat marnet_plus_100km GeoJSON.
+ *
+ * The network is emitted as a single CommonJS asset (JSON string + JSON.parse)
+ * that both the CJS and ESM builds resolve at runtime, instead of being inlined
+ * into each build's marnet module. Shipping it once (as dist/data/marnet.cjs)
+ * roughly halves the published package size.
  *
  * Run manually when refreshing the network:
  *   node scripts/build-marnet.cjs /path/to/marnet_plus_100km.geojson
@@ -9,7 +12,7 @@ const fs = require('fs');
 const path = require('path');
 
 const input = process.argv[2] || '/tmp/eurostat-marnet/marnet_plus_100km.geojson';
-const outPath = path.resolve(__dirname, '..', 'src/lib/marnet.ts');
+const outPath = path.resolve(__dirname, '..', 'data/marnet.cjs');
 
 const src = fs.readFileSync(input, 'utf8');
 const parsed = JSON.parse(src);
@@ -32,33 +35,18 @@ if (json.includes("'") || json.includes('\\')) {
   process.exit(1);
 }
 
-const header = `import type { FeatureCollection, LineString } from "geojson";
-
-/**
- * Maritime network from Eurostat searoute v3.5 (marnet_plus_100km, 2025).
- * 9,847 LineString segments at ~100 km resolution with explicit \`pass\`
- * labels for Suez, Panama, Malacca, Gibraltar, Bab-el-Mandeb, Kiel,
- * Corinth, Dover, Bering, Magellan, Northwest Passage, Northeast Passage.
+const header = `/* Auto-generated by scripts/build-marnet.cjs. Do not edit by hand.
  *
- * Antimeridian normalization: vertices at lon === 180 are rewritten to
- * lon === -180 so the eastern and western sides of the Pacific share a
- * single graph vertex.
+ * Single shared copy of the Eurostat marnet_plus_100km network, loaded by
+ * both the CJS and ESM builds (see src/lib/marnet.ts). Shipping the network
+ * as one asset instead of inlining it into each build roughly halves the
+ * published package size.
  *
  * Source: https://github.com/eurostat/searoute (EUPL-1.2).
- *
- * Embedded as a JSON string so the TypeScript compiler does not
- * pretty-print the 1 MB object literal (which would 2-3x the bundle size).
- * The string is parsed once at module load.
  */
-export type MarnetProperties = { pass?: string };
-
 `;
 
-// eslint-disable-next-line prefer-template
-const body =
-  'const marnetData = JSON.parse(\n  \'' +
-  json +
-  '\',\n) as FeatureCollection<LineString, MarnetProperties>;\n\nexport default marnetData;\n';
+const body = 'module.exports = JSON.parse(\n  \'' + json + '\',\n);\n';
 
 fs.writeFileSync(outPath, header + body);
 console.log('normalized', touched, 'antimeridian vertices');

scripts/copy-marnet.cjs

@@ -0,0 +1,31 @@
+/* Copy the shared network asset into a build output directory.
+ *
+ * The CJS build (dist/cjs/lib), the ESM build (dist/esm/lib) and the test
+ * build (build/test/lib) all import `../../data/marnet.cjs`, which resolves to
+ * `<outRoot>/data/marnet.cjs`. Placing a single copy at that path lets both
+ * published builds share one asset (see issue #10) and lets the test build
+ * find it at runtime.
+ *
+ * Usage:
+ *   node scripts/copy-marnet.cjs dist    # -> dist/data/marnet.cjs (+ .d.cts)
+ *   node scripts/copy-marnet.cjs build   # -> build/data/marnet.cjs (+ .d.cts)
+ */
+const fs = require('fs');
+const path = require('path');
+
+const target = process.argv[2];
+if (!target) {
+  console.error('usage: node scripts/copy-marnet.cjs <output-root>');
+  process.exit(1);
+}
+
+const root = path.resolve(__dirname, '..');
+const srcDir = path.join(root, 'data');
+const outDir = path.resolve(root, target, 'data');
+
+fs.mkdirSync(outDir, { recursive: true });
+for (const file of ['marnet.cjs', 'marnet.d.cts']) {
+  fs.copyFileSync(path.join(srcDir, file), path.join(outDir, file));
+}
+
+console.log('copied network asset to', path.relative(root, outDir));

src/index.spec.ts

@@ -4,6 +4,7 @@ import type { Feature, Point } from 'geojson';
 import {
   CANAL_MAX_DRAFT_M,
   clearFinderCache,
+  DEFAULT_MARNET,
   loadNetwork,
   NoRouteError,
   seaRoute,
@@ -454,6 +455,19 @@ test('seaRouteAlternatives filters near-duplicate-length routes', (t) => {
   t.is(alts.length, 1);
 });
 
+// ── Bundled network asset ────────────────────────────────────────────────────
+
+test('DEFAULT_MARNET loads the shared network asset', (t) => {
+  // The network no longer lives inlined in the compiled module; it is loaded at
+  // runtime from the single shared data/marnet.cjs asset. If that resolution
+  // ever breaks, DEFAULT_MARNET comes back empty (or the import throws).
+  t.is(DEFAULT_MARNET.type, 'FeatureCollection');
+  t.true(DEFAULT_MARNET.features.length > 9000);
+  t.true(DEFAULT_MARNET.features.every((f) => f.geometry.type === 'LineString'));
+  // The Eurostat network carries native `pass` labels on canal/strait edges.
+  t.true(DEFAULT_MARNET.features.some((f) => typeof f.properties?.pass === 'string'));
+});
+
 // ── Custom network ──────────────────────────────────────────────────────────
 
 test('custom network option is honoured', (t) => {