diff --git a/docs/RELEASE.md b/docs/RELEASE.md
index 4efffe0..a5fa118 100644
--- a/docs/RELEASE.md
+++ b/docs/RELEASE.md
@@ -92,7 +92,7 @@ Prepare the self-contained arm64 release candidate:
 npm run release:rc:arm64
 ```
 
-That command prepares portable Python, the pinned core pack, bundled FFmpeg/FFprobe, the frontend, and the release-configured Electron app. It runs the packaged runtime, backend, optional-capability, DMG, signing-readiness, and release-metadata gates, then writes `dist/release-candidate/SHA256SUMS.txt`, `dist/release-candidate/release-manifest.json`, and `dist/release-candidate/RELEASE_NOTES.md`.
+That command prepares portable Python, the pinned core pack, bundled FFmpeg/FFprobe, the frontend, and the release-configured Electron app. The packaged Python is an execution-only private runtime: build/install tooling such as pip/ensurepip, development headers, venv/IDLE, and Tcl/Tk GUI assets are removed after the core pack has been assembled and verified. It runs the packaged runtime, backend, optional-capability, DMG, signing-readiness, and release-metadata gates, then writes `dist/release-candidate/SHA256SUMS.txt`, `dist/release-candidate/release-manifest.json`, and `dist/release-candidate/RELEASE_NOTES.md`.
 
 Run the extended native model gate explicitly when requested:
 
diff --git a/scripts/check-packaged-runtime.js b/scripts/check-packaged-runtime.js
index 6c482a9..76ea57d 100644
--- a/scripts/check-packaged-runtime.js
+++ b/scripts/check-packaged-runtime.js
@@ -153,6 +153,13 @@ function inspectPackage(appPath) {
     fail(`runtime manifest is not valid JSON: ${error.message}`);
   }
   const normalized = validateRuntimeManifest(manifest, { expectedTarget: 'darwin-arm64' });
+  if (
+    normalized.python.profile !== 'execution-only'
+    || normalized.python.buildToolingBundled !== false
+    || normalized.python.guiToolkitBundled !== false
+  ) {
+    fail('packaged Python must declare the execution-only runtime profile without build or GUI tooling');
+  }
   const constraints = manifest.packs?.constraints;
   if (!constraints || typeof constraints.source !== 'string' || !/^[a-f0-9]{64}$/.test(constraints.sha256 || '')) {
     fail('runtime manifest is missing valid core dependency constraints provenance');
@@ -195,6 +202,7 @@ function inspectPackage(appPath) {
   }
 
   const pythonPath = resolveResourcePath(resourcesPath, normalized.python.executable, 'Python executable');
+  const portablePythonRoot = path.dirname(path.dirname(pythonPath));
   const backendRoot = resolveResourcePath(resourcesPath, normalized.backend.root, 'backend root');
   const corePackRoot = resolveResourcePath(resourcesPath, normalized.packs.core, 'core pack root');
   assertExecutable(pythonPath, 'Bundled Python');
@@ -233,6 +241,20 @@ function inspectPackage(appPath) {
   if (!/arm64/i.test(architecture)) fail(`bundled Python architecture is not arm64: ${architecture.trim()}`);
   const forbidden = findForbiddenResourceEntry(resourcesPath);
   if (forbidden) fail(`packaged Resources contains forbidden developer/cache data: ${forbidden}`);
+  for (const relativePath of [
+    'include',
+    'lib/python3.11/site-packages',
+    'lib/python3.11/ensurepip',
+    'lib/python3.11/idlelib',
+    'lib/python3.11/tkinter',
+    'lib/libtcl9.0.dylib',
+    'lib/libtcl9tk9.0.dylib',
+    'bin/pip',
+  ]) {
+    if (fs.existsSync(path.join(portablePythonRoot, ...relativePath.split('/')))) {
+      fail(`packaged portable Python still contains build-only tooling: ${relativePath}`);
+    }
+  }
   const bundledModel = findResourceFile(resourcesPath, 'base.pt');
   if (bundledModel) fail(`packaged Resources contains the Whisper model weight: ${path.relative(resourcesPath, bundledModel)}`);
 
@@ -249,6 +271,7 @@ function inspectPackage(appPath) {
   console.log(`Backend: ${backendSize} bytes`);
   console.log(`FFmpeg/bin: ${binSize} bytes`);
   console.log(`Manifest: ${normalized.schema}, ${normalized.target.id}, Python ${normalized.python.version}`);
+  console.log('Python profile: execution-only; build tooling: No; GUI toolkit: No');
   console.log(`Core constraints: ${constraints.source}, SHA-256 ${constraints.sha256}`);
   console.log(`Core dependency lock: ${dependencyLock.source}, SHA-256 ${dependencyLock.sha256}, requireHashes=true, buildIsolation=false`);
   console.log(`Model manifest: ${modelManifest.id}, ${modelManifest.revision}, ${modelManifest.expectedBytes} bytes`);
diff --git a/scripts/prepare-python-runtime.js b/scripts/prepare-python-runtime.js
index ba6eec9..f005a54 100644
--- a/scripts/prepare-python-runtime.js
+++ b/scripts/prepare-python-runtime.js
@@ -28,6 +28,37 @@ const coreConstraintsPath = path.join(root, 'runtime', 'core-darwin-arm64-py311.
 const coreLockPath = path.join(root, 'runtime', 'core-darwin-arm64-py311.lock.txt');
 // Torch imports torch.testing through its normal autograd import path.
 const RUNTIME_REQUIRED_TEST_DIRECTORIES = new Set(['torch/testing']);
+const PORTABLE_RUNTIME_BUILD_ONLY_PATHS = [
+  'include',
+  'lib/pkgconfig',
+  'lib/python3.11/site-packages',
+  'lib/python3.11/ensurepip',
+  'lib/python3.11/idlelib',
+  'lib/python3.11/pydoc_data',
+  'lib/python3.11/tkinter',
+  'lib/python3.11/turtledemo',
+  'lib/python3.11/lib2to3',
+  'lib/python3.11/venv',
+  'lib/python3.11/lib-dynload/_tkinter.cpython-311-darwin.so',
+  'lib/tcl9.0',
+  'lib/tcl9',
+  'lib/tk9.0',
+  'lib/itcl4.3.8',
+  'lib/thread3.0.6',
+  'lib/libtcl9.0.dylib',
+  'lib/libtcl9tk9.0.dylib',
+  'bin/2to3',
+  'bin/2to3-3.11',
+  'bin/idle3',
+  'bin/idle3.11',
+  'bin/pip',
+  'bin/pip3',
+  'bin/pip3.11',
+  'bin/pydoc3',
+  'bin/pydoc3.11',
+  'bin/python3-config',
+  'bin/python3.11-config',
+];
 
 function getOption(name) {
   const index = process.argv.indexOf(name);
@@ -280,6 +311,9 @@ function writeManifest(relativeInterpreter, version) {
       build: PYTHON_RUNTIME_ARTIFACT.build,
       source: PYTHON_RUNTIME_ARTIFACT.source,
       archiveSha256: PYTHON_RUNTIME_ARTIFACT.sha256,
+      profile: 'execution-only',
+      buildToolingBundled: false,
+      guiToolkitBundled: false,
     },
     backend: { root: 'backend' },
     packs: {
@@ -394,6 +428,23 @@ function prunePackageTestArtifacts(directory) {
   return removed;
 }
 
+function prunePortableRuntimeBuildTooling() {
+  const removed = { paths: 0, files: 0, bytes: 0 };
+  for (const relativePath of PORTABLE_RUNTIME_BUILD_ONLY_PATHS) {
+    const entryPath = path.join(runtimeRoot, ...relativePath.split('/'));
+    if (!fs.lstatSync(entryPath, { throwIfNoEntry: false })) fail(`expected portable build-only path is missing: ${relativePath}`);
+    const stats = directoryStats(entryPath);
+    fs.rmSync(entryPath, { recursive: true, force: false });
+    if (fs.lstatSync(entryPath, { throwIfNoEntry: false })) {
+      fail(`portable build-only path still exists after pruning: ${relativePath}`);
+    }
+    removed.paths += 1;
+    removed.files += stats.files;
+    removed.bytes += stats.bytes;
+  }
+  return removed;
+}
+
 async function main() {
   verifyTarget();
   fs.mkdirSync(buildRoot, { recursive: true });
@@ -408,9 +459,11 @@ async function main() {
   console.log(`Core pack bytes before pruning: ${coreBefore.bytes}`);
   const headersRemoved = pruneNonRuntimeCoreArtifacts();
   const testsRemoved = prunePackageTestArtifacts(corePackRoot);
+  const portableBuildToolingRemoved = prunePortableRuntimeBuildTooling();
   const coreAfter = directoryStats(corePackRoot);
   console.log(`Torch headers removed: ${headersRemoved.files}`);
   console.log(`Package test artifacts removed: ${testsRemoved.directories} directories, ${testsRemoved.files} files, ${testsRemoved.bytes} bytes`);
+  console.log(`Portable Python build-only tooling removed: ${portableBuildToolingRemoved.paths} paths, ${portableBuildToolingRemoved.files} files, ${portableBuildToolingRemoved.bytes} bytes`);
   console.log(`Core pack files after pruning: ${coreAfter.files}`);
   console.log(`Core pack bytes after pruning: ${coreAfter.bytes}`);
   verifyCore(interpreterPath, relativeInterpreter);
diff --git a/scripts/smoke-runtime-artifacts.js b/scripts/smoke-runtime-artifacts.js
index 49c6161..ace151b 100644
--- a/scripts/smoke-runtime-artifacts.js
+++ b/scripts/smoke-runtime-artifacts.js
@@ -36,7 +36,21 @@ const runtimePreparation = fs.readFileSync(path.join(__dirname, 'prepare-python-
 assert.match(runtimePreparation, /function\s+pruneNonRuntimeCoreArtifacts\s*\(/);
 assert.match(runtimePreparation, /function\s+prunePythonBytecode\s*\(/);
 assert.match(runtimePreparation, /function\s+prunePackageTestArtifacts\s*\(/);
+assert.match(runtimePreparation, /function\s+prunePortableRuntimeBuildTooling\s*\(/);
+assert.match(runtimePreparation, /profile:\s*['"]execution-only['"]/);
+assert.match(runtimePreparation, /buildToolingBundled:\s*false/);
+assert.match(runtimePreparation, /guiToolkitBundled:\s*false/);
 assert.match(runtimePreparation, /RUNTIME_REQUIRED_TEST_DIRECTORIES\s*=\s*new Set\(\[['"]torch\/testing['"]\]\)/);
+for (const expectedBuildOnlyPath of [
+  'lib/python3.11/site-packages',
+  'lib/python3.11/ensurepip',
+  'lib/python3.11/tkinter',
+  'lib/python3.11/lib-dynload/_tkinter.cpython-311-darwin.so',
+  'lib/libtcl9.0.dylib',
+  'lib/libtcl9tk9.0.dylib',
+]) {
+  assert.ok(runtimePreparation.includes(`'${expectedBuildOnlyPath}'`), `portable runtime prune is missing ${expectedBuildOnlyPath}`);
+}
 assert.match(runtimePreparation, /['"]--no-compile['"]/);
 assert.match(runtimePreparation, /['"]--no-build-isolation['"]/);
 assert.match(runtimePreparation, /['"]--require-hashes['"]/);