fix: Append to existing .assetsignore, not overwriting (#12628)

Co-authored-by: devin-ai-integration[bot] <158243242+devin-ai-integration[bot]@users.noreply.github.com>

Author: Master-Hash

.changeset/cool-oranges-fail.md

@@ -0,0 +1,7 @@
+---
+"@cloudflare/vite-plugin": patch
+---
+
+Append Cloudflare defaults to existing `.assetsignore` files during build output
+
+When a project includes a `PUBLIC_DIR/.assetsignore`, the plugin now preserves those rules and appends the required `wrangler.json` and `.dev.vars` entries instead of replacing the file content.

packages/vite-plugin-cloudflare/playground/assets/__tests__/assets.spec.ts

@@ -1,5 +1,13 @@
+import * as fs from "node:fs";
+import * as path from "node:path";
 import { test } from "vitest";
-import { getResponse, page, viteTestUrl } from "../../__test-utils__";
+import {
+	getResponse,
+	isBuild,
+	page,
+	rootDir,
+	viteTestUrl,
+} from "../../__test-utils__";
 import "./base-tests";
 
 test("fetches transformed HTML asset", async ({ expect }) => {
@@ -25,3 +33,15 @@ test("fetches original HTML asset if requested directly", async ({
 	const content = await page.textContent("h1");
 	expect(content).toBe("Original content");
 });
+
+test.runIf(isBuild)(
+	"emits .assetsignore in client output directory merged with defaults",
+	({ expect }) => {
+		expect(
+			fs.readFileSync(
+				path.join(rootDir, "dist", "client", ".assetsignore"),
+				"utf-8"
+			)
+		).toBe(`test-file.txt\n*.bak\nwrangler.json\n.dev.vars\n`);
+	}
+);

packages/vite-plugin-cloudflare/playground/assets/public/.assetsignore

@@ -0,0 +1,2 @@
+test-file.txt
+*.bak

packages/vite-plugin-cloudflare/src/plugins/output-config.ts

@@ -1,4 +1,5 @@
 import assert from "node:assert";
+import { existsSync, readFileSync } from "node:fs";
 import * as path from "node:path";
 import { MAIN_ENTRY_NAME } from "../cloudflare-environment";
 import { assertIsNotPreview } from "../context";
@@ -86,12 +87,18 @@ export const outputConfigPlugin = createPlugin("output-config", (ctx) => {
 					}
 				}
 			} else if (this.environment.name === "client") {
-				const filesToAssetsIgnore = ["wrangler.json", ".dev.vars"];
+				const filesToAssetsIgnore = ["wrangler.json", ".dev.vars"] as const;
+				const existingAssetsIgnoreContent =
+					ctx.resolvedViteConfig.publicDir.length > 0
+						? readAssetsIgnoreFile(
+								path.join(ctx.resolvedViteConfig.publicDir, ".assetsignore")
+							)
+						: "";
 
 				this.emitFile({
 					type: "asset",
 					fileName: ".assetsignore",
-					source: `${filesToAssetsIgnore.join("\n")}\n`,
+					source: `${existingAssetsIgnoreContent}${filesToAssetsIgnore.join("\n")}\n`,
 				});
 
 				// For assets only projects the `wrangler.json` file is emitted in the client output directory
@@ -143,6 +150,16 @@ export const outputConfigPlugin = createPlugin("output-config", (ctx) => {
 	};
 });
 
+function readAssetsIgnoreFile(assetsIgnorePath: string): string {
+	const content = existsSync(assetsIgnorePath)
+		? readFileSync(assetsIgnorePath, "utf-8")
+		: "";
+	if (content.length === 0) {
+		return "";
+	}
+	return content.at(-1) === "\n" ? content : `${content}\n`;
+}
+
 function getAssetsDirectory(
 	workerOutputDirectory: string,
 	resolvedViteConfig: vite.ResolvedConfig