feat(installer): filter the boot USB out of the install drive picker

On bare-metal installs, `lsblk` reports the USB stick the live ISO
booted from as TYPE=disk, so it showed up in the drive picker
alongside the real install target — a user could in theory pick the
USB they had just booted from. `findmnt /run/archiso/bootmnt` resolves
the boot partition and `lsblk -no PKNAME` walks it up to the parent
disk; that disk is dropped before scoring. On a normal box neither
file nor mountpoint exist and the picker is unchanged.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_drives.py

@@ -95,3 +95,23 @@ def test_drive_type_label_nvme_ssd_hdd():
 
 def test_parse_lsblk_handles_empty_output():
     assert parse_lsblk_output("") == []
+
+
+def test_parse_lsblk_drops_boot_usb(monkeypatch):
+    import drives
+
+    monkeypatch.setattr(drives, "_smart_status", lambda _: "passed")
+    output = "sda    500G disk\nsdb     16G disk\nnvme0n1  1T disk\n"
+    devices = parse_lsblk_output(output, boot_disk="sdb")
+    names = [d["name"] for d in devices]
+    assert "/dev/sdb" not in names
+    assert names == ["/dev/nvme0n1", "/dev/sda"]
+
+
+def test_parse_lsblk_no_boot_disk_keeps_all(monkeypatch):
+    import drives
+
+    monkeypatch.setattr(drives, "_smart_status", lambda _: "passed")
+    output = "sda 500G disk\nsdb  16G disk\n"
+    names = [d["name"] for d in parse_lsblk_output(output, boot_disk=None)]
+    assert set(names) == {"/dev/sda", "/dev/sdb"}

webinstaller/drives.py

@@ -1,6 +1,41 @@
 import subprocess
 
 
+def _boot_disk_name():
+    """Return the parent disk name of the live-ISO boot media (e.g. "sdb"), or None.
+
+    On a normal box `/run/archiso/bootmnt` does not exist and we return None,
+    leaving the device list untouched. On bare metal booted from USB this is
+    the stick we booted from — we want to filter it out so the user can't
+    accidentally pick it as the install target.
+    """
+    try:
+        result = subprocess.run(
+            ["findmnt", "-no", "SOURCE", "/run/archiso/bootmnt"],
+            capture_output=True,
+            text=True,
+        )
+    except FileNotFoundError:
+        return None
+    if result.returncode != 0:
+        return None
+    partition = result.stdout.strip()
+    if not partition:
+        return None
+    try:
+        parent = subprocess.run(
+            ["lsblk", "-no", "PKNAME", partition],
+            capture_output=True,
+            text=True,
+        )
+    except FileNotFoundError:
+        return None
+    if parent.returncode != 0:
+        return None
+    name = parent.stdout.strip().splitlines()[0] if parent.stdout.strip() else ""
+    return name or None
+
+
 def _smart_status(device):
     try:
         result = subprocess.run(
@@ -75,11 +110,14 @@ def score_device(device, size_gb):
     return get_drive_type_score(device) + get_drive_health(device) + get_size_score(size_gb)
 
 
-def parse_lsblk_output(output):
+def parse_lsblk_output(output, boot_disk=None):
     """Parse `lsblk -dn -o NAME,SIZE,TYPE` output into scored device dicts.
 
     Keeps only TYPE=disk so the live ISO's own squashfs (loop) and the boot
-    CD-ROM (rom) don't show up as install targets.
+    CD-ROM (rom) don't show up as install targets. If `boot_disk` is given,
+    that disk is also dropped — it's the USB stick the live ISO booted from
+    on bare metal, where it appears as TYPE=disk and would otherwise be a
+    valid-looking install target.
     """
     devices = []
     for line in output.strip().split("\n"):
@@ -91,6 +129,8 @@ def parse_lsblk_output(output):
         name, size, dev_type = parts[0], parts[1], parts[2]
         if dev_type != "disk":
             continue
+        if boot_disk and name == boot_disk:
+            continue
         device = f"/dev/{name}"
         size_gb = parse_size_gb(size)
         status = _smart_status(device)
@@ -120,7 +160,7 @@ def list_scored_devices():
     except subprocess.CalledProcessError as e:
         print(f"Error listing devices: {e}")
         return []
-    return parse_lsblk_output(result.stdout)
+    return parse_lsblk_output(result.stdout, boot_disk=_boot_disk_name())
 
 
 def main():