modify harness framework

Codex/Coding/harness framework cs/scripts/dotnet_harness/toolchain.py

@@ -0,0 +1,41 @@
+import re
+import shutil
+import subprocess
+import time
+from pathlib import Path
+
+from .models import Toolchain
+
+
+class ToolchainError(RuntimeError):
+    pass
+
+
+def _decode(value):
+    return value if isinstance(value, str) else (value or b"").decode("utf-8", errors="replace")
+
+
+def discover_toolchain(root: Path, *, which=shutil.which, run=subprocess.run, deadline=None, clock=time.monotonic) -> Toolchain:
+    root = root.resolve()
+    executable = which("dotnet")
+    if executable is None or not Path(executable).is_file():
+        raise ToolchainError("dotnet not found; install .NET SDK 8 and check PATH and global.json")
+    executable = Path(executable).resolve()
+    argv = [str(executable), "--version"]
+    context = f"argv={argv!r}; cwd={str(root)!r}; check .NET SDK 8 and global.json"
+    timeout = 1800 if deadline is None else min(1800, deadline - clock())
+    if timeout <= 0:
+        raise ToolchainError(f"SDK probe timed out before it could start; {context}")
+    try:
+        result = run(argv, cwd=root, capture_output=True, check=False, shell=False, timeout=timeout)
+    except subprocess.TimeoutExpired as exc:
+        raise ToolchainError(f"SDK probe timed out; {context}") from exc
+    except OSError as exc:
+        raise ToolchainError(f"SDK probe could not start: {exc}; {context}") from exc
+    if result.returncode != 0:
+        diagnostic = (_decode(result.stdout) + "\n" + _decode(result.stderr)).strip()[-8000:]
+        raise ToolchainError(f"SDK probe failed with exit code {result.returncode}; {context}; output tail: {diagnostic}")
+    version = _decode(result.stdout).strip()
+    if not re.fullmatch(r"8\.0\.\d+", version):
+        raise ToolchainError(f"expected stable .NET SDK 8, got {version!r}; {context}")
+    return Toolchain(executable, version)