feat(core): replace SystemJS runner with transformed ESM runner

Author: SyMind

.github/actions/build-esm-runner-transform/action.yml

@@ -0,0 +1,25 @@
+name: Build ESM runner transform
+description: Build the SWC WASM plugin used by the transformed ESM runner
+
+runs:
+  using: composite
+  steps:
+    - name: Install WASI target
+      shell: bash
+      run: rustup target add wasm32-wasip1
+
+    - name: Build WASM plugin
+      shell: bash
+      run: >-
+        cargo build
+        --manifest-path packages/core/swc-plugins/esm-runner-transform/Cargo.toml
+        --locked
+        --release
+        --target wasm32-wasip1
+
+    - name: Copy WASM plugin
+      shell: bash
+      run: >-
+        cp
+        packages/core/swc-plugins/esm-runner-transform/target/wasm32-wasip1/release/rsbuild_swc_esm_runner_transform.wasm
+        packages/core/static/swc-esm-runner-transform.wasm

.github/workflows/lint.yml

@@ -29,6 +29,9 @@ jobs:
           node-version: 24.18.1
           package-manager-cache: false
 
+      - name: Build ESM runner transform
+        uses: ./.github/actions/build-esm-runner-transform
+
       - name: Install Pnpm
         uses: pnpm/action-setup@0977fd99725f1db4007ccb2928dbb4e90d06cc86 # v6.0.10
         with:

.github/workflows/preview.yml

@@ -25,6 +25,9 @@ jobs:
           fetch-depth: 1
           ref: ${{ github.event.inputs.branch }}
 
+      - name: Build ESM runner transform
+        uses: ./.github/actions/build-esm-runner-transform
+
       - name: Setup Node.js
         uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
         with:

.github/workflows/release.yml

@@ -68,6 +68,9 @@ jobs:
           fetch-depth: 1
           ref: ${{ github.event.inputs.branch }}
 
+      - name: Build ESM runner transform
+        uses: ./.github/actions/build-esm-runner-transform
+
       - name: Setup Node.js
         uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
         with:

.github/workflows/test.yml

@@ -51,6 +51,10 @@ jobs:
           node-version: 24.18.1
           package-manager-cache: false
 
+      - name: Build ESM runner transform
+        if: steps.changes.outputs.changed == 'true'
+        uses: ./.github/actions/build-esm-runner-transform
+
       - name: Install Pnpm
         if: steps.changes.outputs.changed == 'true'
         uses: pnpm/action-setup@0977fd99725f1db4007ccb2928dbb4e90d06cc86 # v6.0.10
@@ -99,6 +103,10 @@ jobs:
           node-version: 24.18.1
           package-manager-cache: false
 
+      - name: Build ESM runner transform
+        if: steps.changes.outputs.changed == 'true'
+        uses: ./.github/actions/build-esm-runner-transform
+
       - name: Install Pnpm
         if: steps.changes.outputs.changed == 'true'
         uses: pnpm/action-setup@0977fd99725f1db4007ccb2928dbb4e90d06cc86 # v6.0.10

packages/core/src/server/runner/basic.ts

@@ -34,6 +34,7 @@ const getSubPath = (p: string) => {
 
 export interface IBasicRunnerOptions {
   name: string;
+  bundleFiles?: ReadonlyMap<string, string>;
   isBundleOutput: (modulePath: string) => boolean;
   readFileSync: (path: string) => string;
   dist: string;

packages/core/src/server/runner/index.ts

@@ -4,7 +4,7 @@
 import { color, require } from '../../helpers';
 import { CommonJsRunner } from './cjs';
 import { EsmRunner } from './esm';
-import { SystemJsRunner } from './systemJs';
+import { TransformedEsmRunner } from './transformedEsm';
 import type { Runner, RunnerFactory, RunnerFactoryOptions } from './type';
 
 class BasicRunnerFactory implements RunnerFactory {
@@ -42,7 +42,7 @@ class BasicRunnerFactory implements RunnerFactory {
       return new EsmRunner(runnerOptions);
     }
 
-    return new SystemJsRunner(runnerOptions);
+    return new TransformedEsmRunner(runnerOptions);
   }
 }