diff --git a/.github/workflows/nodejs.yml b/.github/workflows/nodejs.yml
index a46038432..49f725c7d 100644
--- a/.github/workflows/nodejs.yml
+++ b/.github/workflows/nodejs.yml
@@ -25,6 +25,8 @@ jobs:
         include:
           - os: macos-14
             node-version: 24
+          - os: macos-15-intel
+            node-version: 24
           - os: windows-2022
             node-version: 24
     steps:
@@ -66,3 +68,50 @@ jobs:
             node/build/**
             prebuilds/**
             **/npm-debug.log
+
+  # Install the packed npm tarball without prebuilt binaries, so the
+  # node-gyp source build path is exercised exactly as it runs on platforms
+  # without a scoped binary package (issue #1409).
+  pack-source-install:
+    name: Source build from npm tarball (${{ matrix.os }})
+    permissions:
+      contents: read
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, macos-15-intel]
+    steps:
+      - uses: actions/checkout@v5
+        with:
+          fetch-depth: 0
+      - name: Use Node.js
+        uses: actions/setup-node@v5
+        with:
+          node-version: 24
+      - run: npm ci
+      - name: Build prebuild assets
+        run: npm run prebuild
+      - name: Pack npm tarball
+        shell: bash
+        run: |
+          mkdir -p dist/npm-artifacts
+          npm pack --pack-destination dist/npm-artifacts
+      - name: Install tarball from source and smoke test
+        shell: bash
+        run: |
+          tarball="$(ls "$PWD"/dist/npm-artifacts/opencc-*.tgz)"
+          install_dir="$(mktemp -d)"
+          cd "$install_dir"
+          npm init -y
+          npm install --omit=optional --foreground-scripts "$tarball"
+          test -f node_modules/opencc/build/Release/opencc.node
+          node -e '
+            const assert = require("assert");
+            const OpenCC = require("opencc");
+            const converter = new OpenCC("s2t.json");
+            const converted = converter.convertSync("汉字");
+            assert.strictEqual(converted, "漢字");
+            console.log("Source-built opencc converts 汉字 ->", converted);
+          '
diff --git a/.github/workflows/release-npm-binaries.yml b/.github/workflows/release-npm-binaries.yml
index b79968d2e..9fa6494ca 100644
--- a/.github/workflows/release-npm-binaries.yml
+++ b/.github/workflows/release-npm-binaries.yml
@@ -32,6 +32,9 @@ jobs:
           - target: darwin-arm64
             runner: macos-15
             library: libopencc-jieba.dylib
+          - target: darwin-x64
+            runner: macos-15-intel
+            library: libopencc-jieba.dylib
           - target: linux-arm64
             runner: ubuntu-24.04-arm
             library: libopencc-jieba.so
@@ -194,6 +197,8 @@ jobs:
         include:
           - target: darwin-arm64
             runner: macos-15
+          - target: darwin-x64
+            runner: macos-15-intel
           - target: linux-arm64
             runner: ubuntu-24.04-arm
           - target: linux-x64
diff --git a/package.json b/package.json
index f99c78ef3..1cc5be762 100644
--- a/package.json
+++ b/package.json
@@ -72,6 +72,7 @@
     "src/Common.hpp",
     "src/Config.cpp",
     "src/Config.hpp",
+    "src/ConfigBasedConverter.hpp",
     "src/Conversion.cpp",
     "src/Conversion.hpp",
     "src/ConversionChain.cpp",
@@ -98,9 +99,12 @@
     "src/MaxMatchSegmentation.cpp",
     "src/MaxMatchSegmentation.hpp",
     "src/opencc.h",
+    "src/opencc_config_schema.inc",
     "src/Optional.hpp",
     "src/PhraseExtract.cpp",
     "src/PhraseExtract.hpp",
+    "src/PipelineConverter.cpp",
+    "src/PipelineConverter.hpp",
     "src/plugin/OpenCCPlugin.h",
     "src/PluginSegmentation.cpp",
     "src/PluginSegmentation.hpp",
@@ -117,6 +121,8 @@
     "src/SerializedValues.hpp",
     "src/SimpleConverter.cpp",
     "src/SimpleConverter.hpp",
+    "src/SingleStageConverter.cpp",
+    "src/SingleStageConverter.hpp",
     "src/TextDict.cpp",
     "src/TextDict.hpp",
     "src/UTF8StringSlice.cpp",
diff --git a/scripts/verify-node-main-package.js b/scripts/verify-node-main-package.js
index 554ab5a0c..742fa9933 100644
--- a/scripts/verify-node-main-package.js
+++ b/scripts/verify-node-main-package.js
@@ -35,6 +35,97 @@ function fail(message) {
   process.exitCode = 1;
 }
 
+// The npm tarball must contain every file the node-gyp source build compiles
+// or includes, so that installs without a prebuilt binary (issue #1409) can
+// fall back to building from source. Walk the gyp source list and its
+// #include closure and check each file against the "files" whitelist.
+function parseGypSourcesAndIncludeDirs() {
+  const gypiPath = path.join(packageRoot, 'node', 'node_opencc.gypi');
+  const gypi = fs.readFileSync(gypiPath, 'utf8');
+  const sources = [];
+  const includeDirs = [];
+  for (const match of gypi.matchAll(/"\.\.(\/[^"]*)?"/g)) {
+    const relativePath = match[1] ? match[1].slice(1) : '.';
+    if (/\.(cpp|cc)$/.test(relativePath)) {
+      sources.push(relativePath);
+    } else if (
+      fs.existsSync(path.join(packageRoot, relativePath)) &&
+      fs.statSync(path.join(packageRoot, relativePath)).isDirectory()
+    ) {
+      includeDirs.push(relativePath);
+    }
+  }
+  return { sources, includeDirs };
+}
+
+function collectSourceBuildClosure() {
+  const { sources, includeDirs } = parseGypSourcesAndIncludeDirs();
+  const closure = new Set();
+  const queue = [...sources];
+  while (queue.length > 0) {
+    const relativePath = queue.pop();
+    if (closure.has(relativePath)) {
+      continue;
+    }
+    const filePath = path.join(packageRoot, relativePath);
+    if (!fs.existsSync(filePath)) {
+      fail(`Source build references a file missing from the repository: ${relativePath}`);
+      continue;
+    }
+    closure.add(relativePath);
+    const content = fs.readFileSync(filePath, 'utf8');
+    for (const match of content.matchAll(/^\s*#\s*include\s+"([^"]+)"/gm)) {
+      const include = match[1];
+      const candidates = [
+        path.posix.join(path.posix.dirname(relativePath), include),
+        ...includeDirs.map((dir) => path.posix.normalize(path.posix.join(dir, include))),
+      ];
+      for (const candidate of candidates) {
+        if (fs.existsSync(path.join(packageRoot, candidate))) {
+          queue.push(candidate);
+          break;
+        }
+      }
+    }
+  }
+  return closure;
+}
+
+function isPackedByFilesWhitelist(relativePath, filesList) {
+  for (const pattern of filesList) {
+    if (pattern === relativePath) {
+      return true;
+    }
+    if (!pattern.includes('*') && relativePath.startsWith(`${pattern.replace(/\/$/, '')}/`)) {
+      return true;
+    }
+    if (pattern.includes('*')) {
+      const regex = new RegExp(
+        `^${pattern.split('*').map((part) =>
+          part.replace(/[.+?^${}()|[\]\\]/g, '\\$&')
+        ).join('[^/]*')}$`
+      );
+      if (regex.test(relativePath)) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+function verifySourceBuildFilesPacked() {
+  const filesList = packageJson.files || [];
+  const missing = [...collectSourceBuildClosure()]
+    .filter((relativePath) => !isPackedByFilesWhitelist(relativePath, filesList))
+    .sort();
+  for (const relativePath of missing) {
+    fail(
+      `Source build requires ${relativePath} but it is not covered by ` +
+      'the "files" whitelist in package.json'
+    );
+  }
+}
+
 for (const relativePath of requiredFiles) {
   const filePath = path.join(packageRoot, relativePath);
   if (!fs.existsSync(filePath)) {
@@ -50,6 +141,8 @@ for (const packageName of expectedOptionalPackages) {
   }
 }
 
+verifySourceBuildFilesPacked();
+
 if (process.exitCode) {
   console.error(
     'opencc package is not ready. Run npm run prebuild before publishing.'