Function serviceWorker

frontend/vite.config.ts:139–215

()

	return {
		name: "third-party-licenses",
		buildStart() {
			try {
				execSync("cargo run -p third-party-licenses", { stdio: "inherit" });
			} catch (e) {
				throw new Error("Failed to generate third-party licenses", { cause: e });
			}
		},
		writeBundle(options) {
			copyFileSync(path.resolve(projectRootDir, "third-party-licenses.txt"), path.join(options.dir || "dist", "third-party-licenses.txt"));
		},
	};
}

// Splits the Wasm binary into parts small enough for Cloudflare Pages' 25 MiB single-file limit, rejoined at runtime by `initWasm()` in `src/utility-functions/wasm-loader.ts`.
// Only active when the `SPLIT_WASM` environment variable is set, which CI does for deployments; local builds keep the single file.
function wasmSplitting(): PluginOption {
	const PART_SIZE = 24 * 1024 * 1024;

	let partCount = 1;

	return {
		name: "wasm-splitting",
		config(_, { command }) {
			// Measure the Wasm binary (already built by `cargo run build web` before Vite runs) to decide how many parts are needed
			if (command === "build" && process.env.SPLIT_WASM) {
				const wasmPath = path.resolve(projectRootDir, "wrapper/pkg/graphite_wasm_wrapper_bg.wasm");
				if (!existsSync(wasmPath)) throw new Error(`SPLIT_WASM is set but the Wasm binary is missing at ${wasmPath}`);
				partCount = Math.ceil(statSync(wasmPath).size / PART_SIZE);
			}

			// Bake the part count into the bundle so `initWasm()` knows how many parts to fetch and rejoin
			return { define: { __WASM_PART_COUNT__: String(partCount) } };
		},
		// Synchronous so it completes before the `serviceWorker` plugin's `writeBundle` collects the precache manifest
		writeBundle(options) {
			if (partCount <= 1) return;

			const assetsDir = path.join(options.dir || "dist", "assets");
			const wasmFileName = readdirSync(assetsDir).find((name) => name.startsWith("graphite_wasm_wrapper_bg-") && name.endsWith(".wasm"));
			if (!wasmFileName) throw new Error("Could not find the emitted Wasm asset to split");
			const wasmPath = path.join(assetsDir, wasmFileName);

			const contents = readFileSync(wasmPath);
			if (Math.ceil(contents.length / PART_SIZE) !== partCount) throw new Error("Wasm binary size changed during the build, invalidating the baked-in part count");

			// Replace the single Wasm file with its parts so only they get deployed and precached
			for (let index = 0; index < partCount; index += 1) {
				const partName = wasmFileName.replace(/\.wasm$/, `-part${index}.wasm`);
				writeFileSync(path.join(assetsDir, partName), contents.subarray(index * PART_SIZE, (index + 1) * PART_SIZE));
			}
			rmSync(wasmPath);
		},
	};
}

function serviceWorker(): PluginOption {
	// Files that should never be precached
	const EXCLUDED_FILES = new Set(["service-worker.js"]);