feat(python-sdk): support bundled preset runtime dependencies

python/sdk-runtime/src/deepseek_harness_runtime/__init__.py

@@ -5,8 +5,8 @@ Two runtime carriers coexist under ``runtime/``, both injected by the repo's
 
 - **exe (production)**: single-file Node executables named
   ``dsh-jsonrpc-agent-pkg-<platform>-<arch>`` (platform in {linux, macos}, arch in
-  {x64, arm64}); macOS also uses a sibling ``-spawn-helper``. The target machine
-  needs no Node installation.
+  {x64, arm64}) with a sibling ``-rg`` executable; macOS also uses a sibling
+  ``-spawn-helper``. The target machine needs no Node installation.
 - **node (dev-only)**: the full deploy closure under ``runtime/node/``
   (``package.json`` + ``node_modules/``), executed as ``node
   runtime/node/node_modules/@deepseek-ai/dsh-sdk-jsonrpc-demo/lib/packaged-bin.js`` on a
@@ -83,6 +83,12 @@ def bundled_runtime_path() -> Path:
             f"deepseek-harness-runtime-bin is missing the runtime executable at {path}. "
             + _EXE_ACQUISITION_HINT
         )
+    ripgrep = Path(f"{path}-rg")
+    if not ripgrep.is_file():
+        raise FileNotFoundError(
+            f"deepseek-harness-runtime-bin is missing the ripgrep sidecar at {ripgrep}. "
+            + _EXE_ACQUISITION_HINT
+        )
     if tag.startswith("macos-"):
         helper = Path(f"{path}-spawn-helper")
         if not helper.is_file():