Generate TS API from Go source (#4915)

Author: weswigham

.github/copilot-instructions.md

@@ -37,6 +37,12 @@ npx hereby format # Format the code
 ```
 </critical>
 
+If you are writing or testing TS API features (eg, code in _packages/native-preview/src/api/async/api.ts), additionally, you need to run
+```sh
+npx hereby test:api
+```
+which is not run as part of the primary suite.
+
 ## Compiler Features, Fixes, and Tests
 
 When fixing a bug or implementing a new feature, at least one minimal test case should always be added in advance to verify the fix.

Herebyfile.mjs

@@ -577,6 +577,12 @@ export const generateAST = task({
     run: () => $`node --experimental-strip-types --no-warnings ./_scripts/generate.ts`,
 });
 
+export const generateAPI = task({
+    name: "generate:api",
+    description: "Generates API files from internal/api/proto.go and internal/api/session.go.",
+    run: () => $`go -C ./_tools run ./gen-proto ../internal/api/proto.go ../_packages/native-preview/src/api/proto.generated.ts`,
+});
+
 // ── Vendored npm dependencies ───────────────────────────────────
 
 const vendorJsonrpcDir = "_packages/native-preview/vendor/vscode-jsonrpc";
@@ -834,6 +840,7 @@ export const buildAPI = task({
 export const buildAPITests = task({
     name: "build:api:test",
     description: "Builds the @typescript/native-preview JS API tests.",
+    dependencies: [generateEnums, generateAPI],
     run: async () => {
         await $`npm run -w @typescript/native-preview build:test`;
     },

_packages/native-preview/src/api/async/api.ts

@@ -21,6 +21,10 @@ import {
     isSpawnOptions,
     resolveExePath,
 } from "../options.ts";
+import type {
+    APIMethodInfo,
+    SourceFileResponseMethod,
+} from "../proto.ts";
 import {
     combineTimingInfo,
     disabledServerTimingInfo,
@@ -154,15 +158,15 @@ export class Client {
         }
     }
 
-    async apiRequest<T>(method: string, params?: unknown): Promise<T> {
+    async apiRequest<K extends keyof APIMethodInfo>(method: K, params: APIMethodInfo[K]["params"]): Promise<APIMethodInfo[K]["result"]> {
         if (!this.connected) {
             await this.connect();
         }
         if (!this.connection) {
             throw new Error("Connection not established");
         }
 
-        const requestType = new RequestType<unknown, T, void>(method);
+        const requestType = new RequestType<unknown, APIMethodInfo[K]["result"], void>(method);
         if (!this.timing) {
             return this.connection.sendRequest(requestType, params);
         }
@@ -186,8 +190,8 @@ export class Client {
         return result;
     }
 
-    async apiRequestBinary(method: string, params?: unknown): Promise<Uint8Array | undefined> {
-        const response = await this.apiRequest<{ data: string; } | null>(method, params);
+    async apiRequestBinary<K extends SourceFileResponseMethod>(method: K, params: APIMethodInfo[K]["params"]): Promise<Uint8Array | undefined> {
+        const response = await this.apiRequest(method, params);
         if (!response) return undefined;
         const buffer = Buffer.from(response.data, "base64");
         return new Uint8Array(buffer.buffer, buffer.byteOffset, buffer.byteLength);