fix(document): select Office engines from declared native targets

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

@@ -21,6 +21,7 @@ console command requires ``DSH_HOME`` for the same reason.
 
 from __future__ import annotations
 
+import json
 import os
 import platform
 import shutil
@@ -89,13 +90,20 @@ def bundled_runtime_path() -> Path:
                 + _EXE_ACQUISITION_HINT
             )
     office = path.with_name(f"{path.name.removesuffix('.exe')}-office")
-    engine = "wasm" if tag.startswith("linux-") else tag.replace("win-", "win32-").replace("macos-", "darwin-")
-    for required in ("@deepseek-ai/libreoffice-kit/package.json", f"@deepseek-ai/libreoffice-kit-{engine}/prebuilds.json"):
-        if not (office / "node_modules" / required).is_file():
-            raise FileNotFoundError(
-                f"deepseek-harness-runtime-bin is missing the Office sidecar at {office}. "
-                + _EXE_ACQUISITION_HINT
-            )
+    adapter = office / "node_modules/@deepseek-ai/libreoffice-kit/package.json"
+    if not adapter.is_file():
+        raise FileNotFoundError(
+            f"deepseek-harness-runtime-bin is missing the Office sidecar at {office}. "
+            + _EXE_ACQUISITION_HINT
+        )
+    native = tag.replace("win-", "win32-").replace("macos-", "darwin-")
+    declared = json.loads(adapter.read_text(encoding="utf-8")).get("optionalDependencies", {})
+    engine = native if f"@deepseek-ai/libreoffice-kit-{native}" in declared else "wasm"
+    if not (office / "node_modules" / f"@deepseek-ai/libreoffice-kit-{engine}/prebuilds.json").is_file():
+        raise FileNotFoundError(
+            f"deepseek-harness-runtime-bin is missing the Office sidecar engine {engine} at {office}. "
+            + _EXE_ACQUISITION_HINT
+        )
     return path