Add --state-dir option to the Python VM launchers

Let each run-*.py launcher take the VM directory (disk, seed ISO, UEFI
variables, PID file, console log) from the command line, taking
precedence over the *_STATE_DIR environment variable. Paths derived
from the state directory are now computed after argument parsing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K1dybYsc36kf3gUPB7NuNB

run-debian13.py

@@ -52,8 +52,6 @@ else:
     uses_shared_base_image = True
 
 state_dir = Path(env("VM_STATE_DIR") or script_dir / ".vm" / "debian13")
-disk_image = Path(env("VM_DISK_IMAGE") or state_dir / "disk.qcow2")
-seed_image = Path(env("VM_SEED_IMAGE") or disk_image.parent / "seed.iso")
 disk_size = env("VM_DISK_SIZE") or "20G"
 memory = env("VM_MEMORY") or "8G"
 cpus = env("VM_CPUS") or "8"
@@ -117,23 +115,23 @@ else:
         "/opt/homebrew/share/qemu/edk2-i386-vars.fd",
         "/usr/local/share/qemu/edk2-i386-vars.fd",
     )
-uefi_vars = state_dir / "OVMF_VARS_4M.fd"
-pid_file = state_dir / "qemu.pid"
-log_file = state_dir / "console.log"
 daemonize = False
 extra_args = []
 
 
 def usage(stream=sys.stdout):
     stream.write(f"""\
-Usage: {Path(sys.argv[0]).name} [--daemon] [-- QEMU_ARGUMENT ...]
+Usage: {Path(sys.argv[0]).name} [--daemon] [--state-dir DIR] [-- QEMU_ARGUMENT ...]
 
-Start the Debian 13 virtual machine. A writable overlay is created under
-.vm/debian13/, so the downloaded base image is never modified.
+Start the Debian 13 virtual machine. A writable overlay is created in the state
+directory (default: .vm/debian13/), so the downloaded base image is never
+modified.
 
 Options:
-  --daemon  Run in the background while keeping the graphical window
-  -h, --help  Show this help
+  --daemon         Run in the background while keeping the graphical window
+  --state-dir DIR  Directory for the VM disk, seed ISO and runtime files
+                   (default: .vm/debian13; overrides VM_STATE_DIR)
+  -h, --help       Show this help
 
 Environment variables:
   VM_MEMORY      Guest memory (default: 8G)
@@ -156,6 +154,12 @@ while args:
     arg = args.pop(0)
     if arg == "--daemon":
         daemonize = True
+    elif arg == "--state-dir":
+        if not args:
+            die(f"{arg} requires a directory argument.", 2)
+        state_dir = Path(args.pop(0))
+    elif arg.startswith("--state-dir="):
+        state_dir = Path(arg.split("=", 1)[1])
     elif arg in ("-h", "--help"):
         usage()
         sys.exit(0)
@@ -167,6 +171,12 @@ while args:
         usage(sys.stderr)
         sys.exit(2)
 
+disk_image = Path(env("VM_DISK_IMAGE") or state_dir / "disk.qcow2")
+seed_image = Path(env("VM_SEED_IMAGE") or disk_image.parent / "seed.iso")
+uefi_vars = state_dir / "OVMF_VARS_4M.fd"
+pid_file = state_dir / "qemu.pid"
+log_file = state_dir / "console.log"
+
 for command_name in (qemu_binary, "qemu-img"):
     if shutil.which(command_name) is None:
         die(f"{command_name} is not installed.")