Emit "Ferric" into generated files

packages/ferric/src/banner.ts

@@ -10,6 +10,16 @@ const LINES = [
   "╰─────────────────────────╯",
 ];
 
+export function getBlockComment() {
+  return (
+    "/**\n" +
+    ["This file was generated by", ...LINES, "Powered by napi.rs"]
+      .map((line) => ` * ${line}`)
+      .join("\n") +
+    "\n */"
+  );
+}
+
 export function printBanner() {
   console.log(
     LINES.map((line, lineNumber, lines) => {

packages/ferric/src/build.ts

@@ -30,6 +30,7 @@ import {
   filterTargetsByPlatform,
 } from "./targets.js";
 import { generateTypeScriptDeclarations } from "./napi-rs.js";
+import { getBlockComment } from "./banner.js";
 
 type EntrypointOptions = {
   outputPath: string;
@@ -41,7 +42,11 @@ async function generateEntrypoint({
 }: EntrypointOptions) {
   await fs.promises.writeFile(
     outputPath,
-    "module.exports = require('./" + libraryName + ".node');",
+    [
+      "/* eslint-disable */",
+      getBlockComment(),
+      `module.exports = require('./${libraryName}.node');`,
+    ].join("\n\n") + "\n",
     "utf8"
   );
 }

packages/ferric/src/napi-rs.ts

@@ -1,7 +1,9 @@
+import assert from "node:assert/strict";
 import fs from "node:fs";
 import path from "node:path";
 
 import { spawn } from "bufout";
+import { getBlockComment } from "./banner.js";
 
 const PACKAGE_ROOT = path.join(import.meta.dirname, "..");
 
@@ -29,6 +31,7 @@ export async function generateTypeScriptDeclarations({
   const tempPath = fs.realpathSync(
     fs.mkdtempSync(path.join(PACKAGE_ROOT, "dts-tmp-"))
   );
+  const finalOutputPath = path.join(outputPath, outputFilename);
   try {
     // Write a dummy package.json file to avoid errors from napi-rs
     await fs.promises.writeFile(
@@ -56,11 +59,22 @@ export async function generateTypeScriptDeclarations({
         cwd: tempPath,
       }
     );
-    // Copy out the generated TypeScript declarations
-    await fs.promises.copyFile(
-      path.join(tempPath, outputFilename),
-      path.join(outputPath, outputFilename)
+    // Override the banner
+    const tempOutputPath = path.join(tempPath, outputFilename);
+    assert(
+      fs.existsSync(tempOutputPath),
+      `Expected napi.rs to emit ${tempOutputPath}`
+    );
+    const contents = await fs.promises.readFile(tempOutputPath, "utf8");
+    const patchedContents = contents.replace(
+      "/* auto-generated by NAPI-RS */",
+      getBlockComment()
     );
+    // Copy out the generated TypeScript declarations
+    await fs.promises.writeFile(finalOutputPath, patchedContents, {
+      encoding: "utf8",
+    });
+    return finalOutputPath;
   } finally {
     await fs.promises.rm(tempPath, { recursive: true, force: true });
   }