fix(webpack): es module source mapping improvements

packages/webpack5/src/plugins/FixSourceMapUrlPlugin.ts

@@ -0,0 +1,112 @@
+import type { Compiler } from 'webpack';
+import { sources } from 'webpack';
+
+export interface FixSourceMapUrlPluginOptions {
+	outputPath: string;
+}
+
+/**
+ * Ensures sourceMappingURL points to the actual file:// location on device/emulator.
+ * Handles Webpack 5 asset sources (string/Buffer/Source objects).
+ */
+export default class FixSourceMapUrlPlugin {
+	constructor(private readonly options: FixSourceMapUrlPluginOptions) {}
+
+	apply(compiler: Compiler) {
+		const wp: any = (compiler as any).webpack;
+		const hasProcessAssets =
+			!!wp?.Compilation?.PROCESS_ASSETS_STAGE_DEV_TOOLING &&
+			!!(compiler as any).hooks?.thisCompilation;
+
+		const leadingCharacter = process.platform === 'win32' ? '/' : '';
+
+		const toStringContent = (content: any): string => {
+			if (typeof content === 'string') return content;
+			if (Buffer.isBuffer(content)) return content.toString('utf-8');
+			if (content && typeof content.source === 'function') {
+				const inner = content.source();
+				if (typeof inner === 'string') return inner;
+				if (Buffer.isBuffer(inner)) return inner.toString('utf-8');
+				try {
+					return String(inner);
+				} catch {
+					return '';
+				}
+			}
+			try {
+				return String(content);
+			} catch {
+				return '';
+			}
+		};
+
+		const processFile = (filename: string, compilation: any) => {
+			if (!(filename.endsWith('.mjs') || filename.endsWith('.js'))) return;
+
+			// Support both legacy compilation.assets and v5 Asset API
+			let rawSource: any;
+			if (typeof (compilation as any).getAsset === 'function') {
+				const assetObj = (compilation as any).getAsset(filename);
+				if (assetObj && assetObj.source) {
+					rawSource = (assetObj.source as any).source
+						? (assetObj.source as any).source()
+						: (assetObj.source as any)();
+				}
+			}
+			if (
+				rawSource === undefined &&
+				(compilation as any).assets &&
+				(compilation as any).assets[filename]
+			) {
+				const asset = (compilation as any).assets[filename];
+				rawSource = typeof asset.source === 'function' ? asset.source() : asset;
+			}
+
+			let source = toStringContent(rawSource);
+			// Replace sourceMappingURL to use file:// protocol pointing to actual location
+			source = source.replace(
+				/\/\/\# sourceMappingURL=(.+\.map)/g,
+				`//# sourceMappingURL=file://${leadingCharacter}${this.options.outputPath}/$1`,
+			);
+
+			// Prefer Webpack 5 updateAsset with RawSource when available
+			const RawSourceCtor =
+				wp?.sources?.RawSource || (sources as any)?.RawSource;
+			if (
+				typeof (compilation as any).updateAsset === 'function' &&
+				RawSourceCtor
+			) {
+				(compilation as any).updateAsset(filename, new RawSourceCtor(source));
+			} else {
+				(compilation as any).assets[filename] = {
+					source: () => source,
+					size: () => source.length,
+				};
+			}
+		};
+
+		if (hasProcessAssets) {
+			compiler.hooks.thisCompilation.tap(
+				'FixSourceMapUrlPlugin',
+				(compilation: any) => {
+					const stage = wp.Compilation.PROCESS_ASSETS_STAGE_DEV_TOOLING;
+					compilation.hooks.processAssets.tap(
+						{ name: 'FixSourceMapUrlPlugin', stage },
+						(assets: Record<string, any>) => {
+							Object.keys(assets).forEach((filename) =>
+								processFile(filename, compilation),
+							);
+						},
+					);
+				},
+			);
+		} else {
+			// Fallback for older setups: use emit (may log deprecation in newer webpack)
+			compiler.hooks.emit.tap('FixSourceMapUrlPlugin', (compilation: any) => {
+				Object.keys((compilation as any).assets).forEach((filename) =>
+					processFile(filename, compilation),
+				);
+			});
+		}
+	}
+}