Use platform-specific runtime log paths

runtime_launcher.py

@@ -10,6 +10,21 @@
 import sys
 
 
+def setup_log_path(root: Path) -> Path:
+    """Return the log path shared by setup and launcher diagnostics."""
+    configured = os.environ.get("DRUNKENBOT_RUNTIME_SETUP_LOG")
+    if configured:
+        return Path(configured)
+    system = platform.system()
+    if system == "Windows":
+        base = Path(os.environ.get("LOCALAPPDATA", Path.home() / "AppData" / "Local"))
+    elif system == "Darwin":
+        base = Path.home() / "Library" / "Logs"
+    else:
+        base = Path(os.environ.get("XDG_STATE_HOME", Path.home() / ".local" / "state"))
+    return base / "DrunkenBot-IDE" / "runtime_setup.log"
+
+
 def private_python(root: Path) -> Path:
     if platform.system() == "Windows":
         return root / "runtime" / "Scripts" / "python.exe"
@@ -28,6 +43,9 @@ def launch(root: Path) -> int:
         raise RuntimeError(f"Runtime setup is missing: {setup_script}")
     environment = os.environ.copy()
     environment["DRUNKENBOT_APP_ROOT"] = str(root)
+    log_path = setup_log_path(root)
+    log_path.parent.mkdir(parents=True, exist_ok=True)
+    environment["DRUNKENBOT_RUNTIME_SETUP_LOG"] = str(log_path)
     setup_kwargs: dict[str, object] = {
         "cwd": root,
         "env": environment,
@@ -40,7 +58,6 @@ def launch(root: Path) -> int:
         **setup_kwargs,
     )
     if setup_result.returncode != 0:
-        log_path = root / "runtime_setup.log"
         verification = subprocess.run(
             [str(interpreter), "-c", "import torch; print(torch.__version__)"],
             cwd=root,

runtime_setup.py

@@ -62,6 +62,30 @@ def choose_runtime(system: str | None = None, driver_major: int | None = None) -
 _SETUP_LOG = None
 
 
+def _log_path(root: Path) -> Path:
+    """Choose a writable setup-log location on installed systems."""
+    system = platform.system()
+    if system == "Windows":
+        platform_log = Path(os.environ.get("LOCALAPPDATA", Path.home() / "AppData" / "Local"))
+    elif system == "Darwin":
+        platform_log = Path.home() / "Library" / "Logs"
+    else:
+        platform_log = Path(os.environ.get("XDG_STATE_HOME", Path.home() / ".local" / "state"))
+    candidates = [
+        platform_log / "DrunkenBot-IDE" / "runtime_setup.log",
+        root / "runtime_setup.log",
+    ]
+    for candidate in candidates:
+        try:
+            candidate.parent.mkdir(parents=True, exist_ok=True)
+            with candidate.open("a", encoding="utf-8"):
+                pass
+            return candidate
+        except OSError:
+            continue
+    raise OSError("Could not create a writable runtime setup log.")
+
+
 def install_runtime(python_executable: str, choice: RuntimeChoice) -> None:
     environment = os.environ.copy()
     environment["PATH"] = os.pathsep.join(
@@ -124,7 +148,10 @@ def main() -> int:
     parser.add_argument("--dry-run", action="store_true")
     parser.add_argument("--ensure", action="store_true")
     args = parser.parse_args()
-    log_path = Path(__file__).resolve().parent / "runtime_setup.log"
+    configured_log = os.environ.get("DRUNKENBOT_RUNTIME_SETUP_LOG")
+    log_path = Path(configured_log) if configured_log else _log_path(Path(__file__).resolve().parent)
+    log_path.parent.mkdir(parents=True, exist_ok=True)
+    os.environ["DRUNKENBOT_RUNTIME_SETUP_LOG"] = str(log_path)
     with log_path.open("w", encoding="utf-8") as log:
         global _SETUP_LOG
         _SETUP_LOG = log