Use protocol_dts_generator.ts from Chromium checkout

README.md

@@ -9,3 +9,23 @@ Use the [protocol viewer](https://chromedevtools.github.io/devtools-protocol/) f
 TypeScript definitions for the protocol's types are available in ['types/protocol.d.ts'](https://github.com/ChromeDevTools/devtools-protocol/tree/master/types). Mappings from Commands and events to these types are available in either generated `DomainApi` style in [`types/protocol-proxy-api.d.ts`](https://github.com/ChromeDevTools/devtools-protocol/blob/master/types/protocol-proxy-api.d.ts) or in simple name-to-type-interface style in [`types/protocol-mapping.d.ts`](https://github.com/ChromeDevTools/devtools-protocol/blob/master/types/protocol-mapping.d.ts).
 
 Also, this repo is published as the [`devtools-protocol`](https://www.npmjs.com/package/devtools-protocol) npm module.
+
+## Development
+
+The `.pdl` files, the `json/` files and the TypeScript definitions in `types/`
+are all generated by [`scripts/update-to-latest.sh`](scripts/update-to-latest.sh),
+which runs daily. Do not edit them by hand.
+
+The TypeScript generator itself lives in Chromium, at
+[`//third_party/blink/public/devtools_protocol/scripts/protocol_dts_generator.ts`](https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/public/devtools_protocol/scripts/protocol_dts_generator.ts),
+so that Chromium and this repo share a single source of truth. It is fetched
+into `tmp/chromium/` by the sparse checkout in `update-to-latest.sh`. Changes to
+the generator should be made in Chromium.
+
+To regenerate `types/` against an existing local Chromium checkout:
+
+```sh
+cd scripts
+CHROMIUM_PROTOCOL_SCRIPTS_DIR=/path/to/src/third_party/blink/public/devtools_protocol/scripts \
+  npm run build-protocol-dts
+```

scripts/build-protocol-dts.mjs

@@ -0,0 +1,49 @@
+// Regenerates types/*.d.ts using Chromium's protocol_dts_generator.ts.
+//
+// The generator is maintained in Chromium (the single source of truth) at
+// //third_party/blink/public/devtools_protocol/scripts/ and is fetched into
+// tmp/chromium/ by the sparse checkout in scripts/update-to-latest.sh.
+
+import {spawnSync} from 'node:child_process';
+import {existsSync} from 'node:fs';
+import path from 'node:path';
+
+const scriptsDir = import.meta.dirname;
+const repoRoot = path.join(scriptsDir, '..');
+
+const chromiumScriptsDir = process.env.CHROMIUM_PROTOCOL_SCRIPTS_DIR ??
+  path.join(repoRoot, 'tmp/chromium/third_party/blink/public/devtools_protocol/scripts');
+const generator = path.join(chromiumScriptsDir, 'protocol_dts_generator.ts');
+
+if (!existsSync(generator)) {
+  console.error(`
+Could not find Chromium's protocol_dts_generator.ts at:
+  ${generator}
+
+This generator lives in Chromium, not in this repo. To regenerate the types:
+
+  * run scripts/update-to-latest.sh, which sparse-checks out Chromium into
+    tmp/chromium/ and then runs this script, or
+
+  * point at an existing local Chromium checkout:
+      CHROMIUM_PROTOCOL_SCRIPTS_DIR=/path/to/src/third_party/blink/public/devtools_protocol/scripts \\
+        npm run build-protocol-dts
+`);
+  process.exit(1);
+}
+
+const {status} = spawnSync(
+  process.execPath,
+  [
+    // The generator is type-stripped by Node. It lives outside of scripts/, so
+    // the nearest package.json has no "type": "module" and Node would warn.
+    '--disable-warning=MODULE_TYPELESS_PACKAGE_JSON',
+    generator,
+    '--output-dir', path.join(repoRoot, 'types'),
+    path.join(repoRoot, 'json/js_protocol.json'),
+    path.join(repoRoot, 'json/browser_protocol.json'),
+  ],
+  {stdio: 'inherit'},
+);
+
+process.exit(status ?? 1);

scripts/package.json

@@ -3,7 +3,7 @@
   "type": "module",
   "license": "SEE LICENSE IN https://chromium.googlesource.com/chromium/src/+/main/LICENSE",
   "scripts": {
-    "build-protocol-dts": "node protocol-dts-generator.ts",
+    "build-protocol-dts": "node build-protocol-dts.mjs",
     "type-check": "tsc -p tsconfig.json",
     "changelog": "node generate-changelog.mjs"
   },