Diagnostic v2: log on module import, dual log paths, ship debug.bat

v0.3.3 wrapper only logged once it reached _main(). User reports CMD
window flashes shut and no log file created — meaning Python likely
never reached our code. Two fixes:

1. Move first log write to module top (before any project import) and
   write to BOTH the exe directory AND %LOCALAPPDATA%/sephiria_inv/.
   Either log existing proves Python booted; neither existing means
   PyInstaller bootloader itself failed.

2. Add run-debug.bat that runs the exe with stdout/stderr captured to
   sephiria_inv_console.log and pauses, so the window does not close
   before the user can read it.

run-debug.bat

@@ -0,0 +1,22 @@
+@echo off
+REM Run the exe with output captured. Window does not auto-close.
+setlocal
+cd /d "%~dp0"
+echo Running sephiria_inv.exe ...
+echo.
+sephiria_inv.exe > sephiria_inv_console.log 2>&1
+set EC=%errorlevel%
+echo.
+echo === sephiria_inv.exe exited with code %EC% ===
+echo.
+echo --- sephiria_inv_console.log ---
+if exist sephiria_inv_console.log type sephiria_inv_console.log
+echo --- end console.log ---
+echo.
+echo --- sephiria_inv_startup.log ---
+if exist sephiria_inv_startup.log type sephiria_inv_startup.log
+echo --- end startup.log ---
+echo.
+echo Press any key to close this window.
+pause > nul
+endlocal

run.py

@@ -1,6 +1,116 @@
-"""PyInstaller entry shim."""
+"""PyInstaller entry shim with aggressive startup diagnostics.
 
+Writes a log entry the moment this module is loaded (before any project
+imports). Logs to two locations:
+  1. Next to the exe (sys.executable directory) -- usually the user's
+     Downloads folder; trivially findable.
+  2. %LOCALAPPDATA%/sephiria_inv/startup.log
+
+Either log existing tells us Python started. Neither existing means the
+PyInstaller bootloader died before Python ran (DLL/runtime issue).
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+import traceback
+from datetime import datetime
+
+
+def _candidate_log_paths():
+    paths = []
+    # 1. Next to the exe (most discoverable for the user)
+    try:
+        exe_dir = os.path.dirname(os.path.abspath(sys.executable))
+        if exe_dir:
+            paths.append(os.path.join(exe_dir, "sephiria_inv_startup.log"))
+    except Exception:
+        pass
+    # 2. LOCALAPPDATA / home
+    try:
+        base = os.environ.get("LOCALAPPDATA") or os.path.expanduser("~")
+        folder = os.path.join(base, "sephiria_inv")
+        os.makedirs(folder, exist_ok=True)
+        paths.append(os.path.join(folder, "startup.log"))
+    except Exception:
+        pass
+    return paths
+
+
+def _write_log(msg: str) -> list:
+    written = []
+    stamp = datetime.now().isoformat()
+    for path in _candidate_log_paths():
+        try:
+            with open(path, "a", encoding="utf-8") as fh:
+                fh.write(f"\n=== {stamp} ===\n{msg}\n")
+            written.append(path)
+        except Exception:
+            pass
+    return written
+
+
+def _env_dump() -> str:
+    lines = [
+        f"python: {sys.version}",
+        f"executable: {sys.executable}",
+        f"argv: {sys.argv}",
+        f"frozen: {getattr(sys, 'frozen', False)}",
+        f"_MEIPASS: {getattr(sys, '_MEIPASS', '<none>')}",
+        f"cwd: {os.getcwd()}",
+        f"PATH head: {os.environ.get('PATH', '')[:200]}",
+        f"LOCALAPPDATA: {os.environ.get('LOCALAPPDATA', '<none>')}",
+    ]
+    return "\n".join(lines)
+
+
+# === MODULE-IMPORT BREADCRUMB ===
+# This runs the moment Python loads the entry script. If this never appears
+# in either log, the PyInstaller bootloader failed before Python started.
+_BOOT_LOGS = _write_log("BOOT: run.py loaded\n" + _env_dump())
+
+
+def _show_error(title: str, body: str) -> None:
+    try:
+        import tkinter as tk
+        from tkinter import scrolledtext
+        root = tk.Tk()
+        root.title(title)
+        root.geometry("780x460")
+        txt = scrolledtext.ScrolledText(root, wrap="word")
+        txt.pack(fill="both", expand=True)
+        txt.insert("1.0", body)
+        tk.Button(root, text="Close", command=root.destroy).pack(pady=4)
+        root.mainloop()
+    except Exception:
+        pass
+
+
+def _main() -> int:
+    try:
         from sephiria_inv.__main__ import main
+    except BaseException:
+        tb = traceback.format_exc()
+        logs = _write_log("IMPORT FAIL\n" + tb + "\n--env--\n" + _env_dump())
+        _show_error(
+            "sephiria_inv: import failed",
+            f"Failed to import sephiria_inv.__main__\n\nLogs: {logs}\n\n{tb}",
+        )
+        return 11
+    try:
+        return int(main() or 0)
+    except SystemExit:
+        raise
+    except BaseException:
+        tb = traceback.format_exc()
+        logs = _write_log("RUNTIME FAIL\n" + tb)
+        _show_error(
+            "sephiria_inv: runtime error",
+            f"Crashed during main()\n\nLogs: {logs}\n\n{tb}",
+        )
+        return 12
+
 
 if __name__ == "__main__":
-    raise SystemExit(main())
+    raise SystemExit(_main())