Technician tool v0.5

Imported from the Google Drive folder 004-technician_tool/v0.5.

kota_tech/sd/disks.py

@@ -0,0 +1,128 @@
+"""Find SD cards (removable disks) on Windows and macOS.
+
+Safety first: only USB/SD/MMC-attached disks that are not the system or
+boot disk and not larger than MAX_CARD_BYTES are ever offered. Parsers are
+pure functions over the OS tool output so they can be tested without
+hardware.
+"""
+
+from __future__ import annotations
+
+import json
+import plistlib
+import subprocess
+import sys
+from dataclasses import dataclass, field
+
+MAX_CARD_BYTES = 256 * 1024**3         # larger "removable" disks are probably not SD cards
+CARD_BUSES = {"USB", "SD", "MMC"}
+
+
+@dataclass
+class Volume:
+    mount: str           # "E:\\" on Windows, "/Volumes/KOTA" on macOS ("" if not mounted)
+    filesystem: str      # "FAT32", "exFAT", "MS-DOS FAT32", ...
+    label: str
+
+
+@dataclass
+class Disk:
+    id: str              # Windows disk number / macOS "/dev/disk4"
+    name: str
+    size: int
+    bus: str
+    volumes: list[Volume] = field(default_factory=list)
+    has_media: bool = True
+
+    @property
+    def size_text(self) -> str:
+        return f"{self.size / 1e9:.1f} GB" if self.size else "no card"
+
+    @property
+    def label(self) -> str:
+        vols = ", ".join(f"{v.mount or '-'} {v.filesystem} '{v.label}'" for v in self.volumes) or "no volume"
+        return f"Disk {self.id}: {self.name} - {self.size_text} ({self.bus}) - {vols}"
+
+
+# ------------------------------------------------------------------ Windows
+
+WIN_LIST_PS = r"""
+$ErrorActionPreference = 'SilentlyContinue'
+# Filter by bus BEFORE touching partitions: querying volumes of every
+# internal disk made this take >30 s on a machine with several HDDs.
+$out = @(Get-Disk | Where-Object { -not $_.IsSystem -and -not $_.IsBoot -and
+                                   @('USB','SD','MMC') -contains [string]$_.BusType } | ForEach-Object {
+  $d = $_
+  $vols = @(Get-Partition -DiskNumber $d.Number | ForEach-Object {
+      $v = $_ | Get-Volume
+      [pscustomobject]@{ DriveLetter = [string]$_.DriveLetter; FileSystem = [string]$v.FileSystem; Label = [string]$v.FileSystemLabel }
+  })
+  [pscustomobject]@{ Number = $d.Number; FriendlyName = $d.FriendlyName; Size = [int64]$d.Size;
+                     BusType = [string]$d.BusType; Volumes = $vols }
+})
+ConvertTo-Json -InputObject $out -Depth 4 -Compress
+"""
+
+
+def parse_windows(json_text: str) -> list[Disk]:
+    data = json.loads(json_text or "[]")
+    if isinstance(data, dict):     # ConvertTo-Json quirk for one element
+        data = [data]
+    disks = []
+    for d in data:
+        if str(d.get("BusType")) not in CARD_BUSES:
+            continue
+        vols = d.get("Volumes") or []
+        if isinstance(vols, dict):
+            vols = [vols]
+        volumes = [Volume(f"{v['DriveLetter']}:\\" if v.get("DriveLetter") and v["DriveLetter"] not in ("\x00", "") else "",
+                          v.get("FileSystem") or "", v.get("Label") or "") for v in vols]
+        size = int(d.get("Size") or 0)
+        disks.append(Disk(str(d["Number"]), d.get("FriendlyName") or "Disk", size, str(d["BusType"]),
+                          [v for v in volumes if v.mount or v.filesystem], has_media=size > 0))
+    return disks
+
+
+# -------------------------------------------------------------------- macOS
+
+def parse_macos(list_plist: bytes, infos: dict[str, bytes]) -> list[Disk]:
+    """`diskutil list -plist physical` + `diskutil info -plist <disk>` for each."""
+    listing = plistlib.loads(list_plist)
+    disks = []
+    for entry in listing.get("AllDisksAndPartitions", []):
+        ident = entry.get("DeviceIdentifier", "")
+        info = plistlib.loads(infos[ident]) if ident in infos else {}
+        protocol = str(info.get("BusProtocol", ""))
+        removable = bool(info.get("RemovableMedia") or info.get("Removable") or info.get("Ejectable"))
+        internal = bool(info.get("Internal", True))
+        is_root = any(p.get("MountPoint") == "/" for p in entry.get("Partitions", []) + entry.get("APFSVolumes", []))
+        if ident == "disk0" or is_root or not (removable or not internal or protocol in ("USB", "Secure Digital", "SD")):
+            continue
+        vols = [Volume(p.get("MountPoint", ""), p.get("Content", ""), p.get("VolumeName", ""))
+                for p in entry.get("Partitions", [])]
+        size = int(entry.get("Size") or info.get("TotalSize") or 0)
+        bus = "SD" if "Secure Digital" in protocol or protocol == "SD" else (protocol or "USB")
+        disks.append(Disk(f"/dev/{ident}", info.get("MediaName", "Disk"), size, bus, vols, has_media=size > 0))
+    return disks
+
+
+# ------------------------------------------------------------------ public
+
+def list_cards() -> tuple[list[Disk], list[Disk]]:
+    """(cards that may be formatted, readers/disks shown but not offered)."""
+    if sys.platform == "win32":
+        out = subprocess.run(["powershell", "-NoProfile", "-NonInteractive", "-Command", WIN_LIST_PS],
+                             capture_output=True, text=True, timeout=90,
+                             creationflags=subprocess.CREATE_NO_WINDOW).stdout
+        disks = parse_windows(out)
+    elif sys.platform == "darwin":
+        lst = subprocess.run(["diskutil", "list", "-plist", "physical"], capture_output=True, timeout=30).stdout
+        infos = {}
+        for e in plistlib.loads(lst).get("AllDisksAndPartitions", []):
+            ident = e.get("DeviceIdentifier", "")
+            infos[ident] = subprocess.run(["diskutil", "info", "-plist", ident], capture_output=True, timeout=30).stdout
+        disks = parse_macos(lst, infos)
+    else:
+        return [], []
+    ok = [d for d in disks if d.has_media and 0 < d.size <= MAX_CARD_BYTES]
+    return ok, [d for d in disks if d not in ok]

kota_tech/sd/envfile.py

@@ -0,0 +1,151 @@
+"""ENV.TXT for the sensorbox SD card.
+
+Parsing mirrors EnvironmentService::read_env_var in the firmware exactly:
+lines read with a 512-byte buffer, split at the FIRST '=', key compared
+verbatim (no trimming), CR/LF removed from the value only, first match wins.
+So the checks below report what would actually break a box - e.g. a UTF-8
+BOM (Windows Notepad) hides the first key, and "KEY = value" is not "KEY".
+
+The firmware FAT driver has no long-file-name support: the file must be
+the 8.3 name ENV.TXT (case-insensitive) in the card root.
+"""
+
+from __future__ import annotations
+
+import re
+from dataclasses import dataclass
+from pathlib import Path
+
+ENV_NAME = "ENV.TXT"
+BUFFER_NAME = "BUFFER.TXT"          # offline measurements waiting for upload
+LINE_BUF = 512                      # char line[512] in the firmware
+REQUIRED = ("INFLUX_URL", "INFLUX_TOKEN")
+OPTIONAL = ("SSID", "PASSWORD")
+_BOM = b"\xef\xbb\xbf"
+
+
+@dataclass
+class Issue:
+    level: str          # "error" | "warning" | "info"
+    text: str
+
+
+@dataclass
+class EnvConfig:
+    influx_url: str = ""
+    influx_token: str = ""
+    ssid: str = ""
+    password: str = ""
+
+    @property
+    def local_wifi(self) -> bool:
+        return bool(self.ssid or self.password)
+
+    def lines(self) -> list[tuple[str, str]]:
+        out = [("INFLUX_TOKEN", self.influx_token), ("INFLUX_URL", self.influx_url)]
+        if self.local_wifi:
+            out += [("SSID", self.ssid), ("PASSWORD", self.password)]
+        return out
+
+    def render(self) -> bytes:
+        # LF only, no BOM, no quoting: exactly what the firmware parser expects.
+        return "".join(f"{k}={v}\n" for k, v in self.lines()).encode("utf-8")
+
+    def problems(self) -> list[Issue]:
+        issues: list[Issue] = []
+        for key, value in self.lines():
+            if any(c in value for c in "\r\n"):
+                issues.append(Issue("error", f"{key} contains a line break."))
+            if value != value.strip():
+                issues.append(Issue("error", f"{key} starts or ends with a space; the box would use the space too."))
+            if len(f"{key}={value}".encode()) >= LINE_BUF - 1:
+                issues.append(Issue("error", f"{key} is too long for the box (max {LINE_BUF - 2} bytes per line)."))
+        url = self.influx_url.strip()
+        if not url:
+            issues.append(Issue("error", "INFLUX_URL is empty."))
+        elif not re.match(r"^https?://", url):
+            issues.append(Issue("error", "INFLUX_URL must start with https://"))
+        elif not ("/api/v2/write" in url and "bucket=" in url and "org=" in url):
+            issues.append(Issue("error", "INFLUX_URL must be a write URL: .../api/v2/write?bucket=...&org=..."))
+        elif url.startswith("http://"):
+            issues.append(Issue("warning", "INFLUX_URL uses http:// (unencrypted)."))
+        if not self.influx_token:
+            issues.append(Issue("error", "INFLUX_TOKEN is empty."))
+        elif re.search(r"\s", self.influx_token):
+            issues.append(Issue("error", "INFLUX_TOKEN contains spaces."))
+        elif len(self.influx_token) < 20:
+            issues.append(Issue("warning", "INFLUX_TOKEN looks too short."))
+        if self.local_wifi:
+            if not self.ssid or not self.password:
+                issues.append(Issue("error", "Wi-Fi needs both SSID and PASSWORD (the box ignores one without the other)."))
+            if len(self.ssid.encode()) > 32:
+                issues.append(Issue("error", "SSID is longer than 32 bytes."))
+            pw = self.password
+            if pw and not (8 <= len(pw) <= 63 or re.fullmatch(r"[0-9A-Fa-f]{64}", pw)):
+                issues.append(Issue("error", "Wi-Fi PASSWORD must be 8-63 characters (WPA2)."))
+        return issues
+
+
+@dataclass
+class EnvCheck:
+    values: dict[str, str]
+    issues: list[Issue]
+
+    @property
+    def ok(self) -> bool:
+        return not any(i.level == "error" for i in self.issues)
+
+    def masked(self) -> dict[str, str]:
+        out = {}
+        for k, v in self.values.items():
+            out[k] = (v[:4] + "..." + v[-4:] if len(v) > 12 else "***") if k in ("INFLUX_TOKEN", "PASSWORD") else v
+        return out
+
+
+def parse_env(raw: bytes) -> EnvCheck:
+    """Read ENV.TXT the way the firmware does and report what it would see."""
+    issues: list[Issue] = []
+    if raw.startswith(_BOM):
+        issues.append(Issue("error", "File starts with a UTF-8 BOM (saved by Notepad?): the box cannot read the first key. "
+                                     "Re-write the card with the tool."))
+    text = raw.decode("utf-8", errors="replace")
+    values: dict[str, str] = {}
+    for n, line in enumerate(text.split("\n"), 1):
+        if len(line.encode()) >= LINE_BUF - 1:
+            issues.append(Issue("error", f"Line {n} is longer than the box can read."))
+        if "=" not in line:
+            continue
+        key, value = line.split("=", 1)
+        value = value.replace("\r", "")
+        if key != key.strip():
+            issues.append(Issue("error", f"Line {n}: spaces around the key '{key.strip()}' - the box will not find it."))
+        if key in values:
+            issues.append(Issue("warning", f"{key} appears twice; the box uses the first one."))
+            continue
+        values[key] = value
+    for key in REQUIRED:
+        if key not in values:
+            issues.append(Issue("error", f"{key} is missing - the box stops at start-up (white LED)."))
+        elif not values[key]:
+            issues.append(Issue("error", f"{key} is empty."))
+    if values.get("HTTP_SERVER") == "true":
+        issues.append(Issue("warning", "HTTP_SERVER=true: a box with newer firmware starts in Wi-Fi setup mode."))
+    if bool(values.get("SSID")) != bool(values.get("PASSWORD")):
+        issues.append(Issue("warning", "Only one of SSID / PASSWORD is set; the box ignores Wi-Fi settings."))
+    elif values.get("SSID"):
+        issues.append(Issue("info", "Wi-Fi settings present: newer firmware uses this Wi-Fi instead of Matter "
+                                    "(the factory v1.0 firmware ignores them)."))
+    return EnvCheck(values, issues)
+
+
+def load_template(path: Path) -> EnvConfig:
+    """Settings from an existing ENV.TXT (e.g. 002-SD_card_format/ENV.txt)."""
+    v = parse_env(path.read_bytes()).values
+    return EnvConfig(v.get("INFLUX_URL", ""), v.get("INFLUX_TOKEN", ""), v.get("SSID", ""), v.get("PASSWORD", ""))
+
+
+def find_case_insensitive(root: Path, name: str) -> Path | None:
+    for p in root.iterdir() if root.is_dir() else ():
+        if p.is_file() and p.name.lower() == name.lower():
+            return p
+    return None

kota_tech/sd/provision.py

@@ -0,0 +1,273 @@
+"""Format an SD card for the sensorbox and write / check ENV.TXT.
+
+Card format required by the firmware: MBR partition table, FAT32 (its FAT
+driver has no exFAT and no long file names), ENV.TXT in the root.
+
+Windows: formatting needs administrator rights, so a generated PowerShell
+script runs elevated (UAC prompt). The script re-checks the disk (number,
+size, bus, not system/boot) right before erasing it, so a card swapped
+after the technician confirmed is not touched. Windows cannot format FAT32
+above 32 GB, so larger cards get a 32 GB partition (plenty for the box).
+macOS: `diskutil eraseDisk FAT32 KOTA MBRFormat` (same as format_sd.sh).
+"""
+
+from __future__ import annotations
+
+import json
+import os
+import plistlib
+import subprocess
+import sys
+import time
+import uuid
+from dataclasses import dataclass, field
+from pathlib import Path
+
+from .disks import CARD_BUSES, Disk
+from .envfile import BUFFER_NAME, ENV_NAME, EnvCheck, EnvConfig, find_case_insensitive, parse_env
+
+VOLUME_LABEL = "KOTA"
+FAT32_MAX = 32 * 1024**3
+
+
+@dataclass
+class Outcome:
+    ok: bool
+    message: str
+    mount: str = ""
+    log: list[str] = field(default_factory=list)
+
+
+@dataclass
+class CardReport:
+    mount: str
+    filesystem: str
+    env: EnvCheck | None
+    buffered_lines: int | None      # measurements waiting on the card for upload
+    problems: list[str]
+
+
+# ----------------------------------------------------------------- Windows
+
+def windows_format_script(disk: Disk, result_file: Path) -> str:
+    buses = ",".join(f"'{b}'" for b in sorted(CARD_BUSES))
+    return f"""
+$ErrorActionPreference = 'Stop'
+$result = @{{ ok = $false; message = ''; drive = '' }}
+try {{
+  $n = {int(disk.id)}
+  $d = Get-Disk -Number $n
+  if ($d.IsSystem -or $d.IsBoot) {{ throw 'Refusing: this is a system/boot disk.' }}
+  if (@({buses}) -notcontains [string]$d.BusType) {{ throw "Refusing: disk bus is $($d.BusType), not an SD/USB card." }}
+  if ([int64]$d.Size -ne {int(disk.size)}) {{ throw 'Refusing: the disk changed since it was selected (card swapped?).' }}
+  if ($d.PartitionStyle -ne 'RAW') {{ Clear-Disk -Number $n -RemoveData -RemoveOEM -Confirm:$false }}
+  Initialize-Disk -Number $n -PartitionStyle MBR -ErrorAction SilentlyContinue
+  $size = [Math]::Min([int64]$d.Size - 2MB, [int64]{FAT32_MAX})
+  $p = New-Partition -DiskNumber $n -Size $size -MbrType FAT32 -AssignDriveLetter
+  Format-Volume -Partition $p -FileSystem FAT32 -NewFileSystemLabel '{VOLUME_LABEL}' -Confirm:$false -Force | Out-Null
+  Start-Sleep -Seconds 2
+  $letter = (Get-Partition -DiskNumber $n -PartitionNumber $p.PartitionNumber).DriveLetter
+  if (-not $letter) {{ throw 'Formatted, but Windows gave the card no drive letter.' }}
+  $result.ok = $true; $result.drive = "$($letter):\\"; $result.message = 'Formatted FAT32 (MBR).'
+}} catch {{ $result.message = $_.Exception.Message }}
+$result | ConvertTo-Json | Out-File -FilePath '{result_file}' -Encoding utf8
+"""
+
+
+WORK_ROOT = Path.home() / "KotaTechnicianTool" / "tmp"
+
+
+def _workdir() -> Path:
+    # Not tempfile.mkdtemp(): on Windows it creates an owner-only folder, and a
+    # file written there by the ELEVATED script is then unreadable for this
+    # (non-elevated) process. A normally inherited ACL works for both.
+    work = WORK_ROOT / f"sd_{uuid.uuid4().hex[:10]}"
+    work.mkdir(parents=True, exist_ok=False)
+    return work
+
+
+def _query_windows_card(number: int) -> tuple[str, str, str]:
+    """(drive, filesystem, label) of the card's first partition - no admin rights needed."""
+    ps = (f"$p = Get-Partition -DiskNumber {number} -ErrorAction SilentlyContinue | Select-Object -First 1; "
+          "if ($p) { $v = $p | Get-Volume -ErrorAction SilentlyContinue; "
+          "\"$($p.DriveLetter)|$($v.FileSystem)|$($v.FileSystemLabel)\" }")
+    out = subprocess.run(["powershell", "-NoProfile", "-Command", ps], capture_output=True, text=True,
+                         timeout=90, creationflags=subprocess.CREATE_NO_WINDOW).stdout.strip()
+    drive, fs, label = (out.split("|") + ["", "", ""])[:3]
+    return (f"{drive}:\\" if drive.strip() else ""), fs, label
+
+
+def _format_windows(disk: Disk, log: list[str]) -> Outcome:
+    work = _workdir()
+    script, result = work / "format_card.ps1", work / "result.json"
+    script.write_text(windows_format_script(disk, result), encoding="utf-8-sig")
+    log.append("Asking Windows for administrator rights to format the card (UAC prompt)...")
+    launcher = ("$p = Start-Process powershell -Verb RunAs -Wait -PassThru -WindowStyle Hidden "
+                f"-ArgumentList '-NoProfile -ExecutionPolicy Bypass -File \"{script}\"'; exit $p.ExitCode")
+    proc = subprocess.run(["powershell", "-NoProfile", "-Command", launcher], capture_output=True, text=True,
+                          timeout=600, creationflags=subprocess.CREATE_NO_WINDOW)
+    if not result.exists():
+        err = (proc.stderr or "").strip().splitlines()
+        cancelled = any("canceled" in e.lower() or "cancelled" in e.lower() for e in err)
+        return Outcome(False, "Administrator permission was refused - the card was not formatted." if cancelled
+                       else "Formatting did not run: " + (err[-1] if err else "unknown error"), log=log)
+    try:
+        res = json.loads(result.read_text(encoding="utf-8-sig"))
+    except (OSError, ValueError) as exc:
+        # The script ran but its report is unreadable: judge by the card itself.
+        log.append(f"Could not read the format result ({exc.__class__.__name__}); checking the card directly.")
+        drive, fs, label = _query_windows_card(int(disk.id))
+        ok = bool(drive) and fs.upper() == "FAT32" and label == VOLUME_LABEL
+        res = {"ok": ok, "drive": drive,
+               "message": "Formatted FAT32 (MBR)." if ok else f"Card state after formatting: {fs or 'no file system'} "
+                                                              f"'{label}' - formatting probably failed."}
+    log.append(res.get("message", ""))
+    return Outcome(bool(res.get("ok")), res.get("message", ""), res.get("drive", ""), log)
+
+
+def _eject_windows(mount: str) -> bool:
+    """Flush, lock, dismount and eject the card - what 'Safely Remove' does.
+
+    Not Shell.Application InvokeVerb('Eject'): it fails silently because the
+    verb is named 'E&ject' (and is localised on non-English Windows).
+    """
+    import ctypes
+    from ctypes import wintypes
+
+    k32 = ctypes.WinDLL("kernel32", use_last_error=True)
+    k32.CreateFileW.restype = wintypes.HANDLE
+    k32.CreateFileW.argtypes = [wintypes.LPCWSTR, wintypes.DWORD, wintypes.DWORD, wintypes.LPVOID,
+                                wintypes.DWORD, wintypes.DWORD, wintypes.HANDLE]
+    k32.DeviceIoControl.argtypes = [wintypes.HANDLE, wintypes.DWORD, wintypes.LPVOID, wintypes.DWORD,
+                                    wintypes.LPVOID, wintypes.DWORD, ctypes.POINTER(wintypes.DWORD), wintypes.LPVOID]
+    GENERIC_RW, SHARE_RW, OPEN_EXISTING = 0xC0000000, 0x3, 3
+    FSCTL_LOCK_VOLUME, FSCTL_DISMOUNT_VOLUME = 0x00090018, 0x00090020
+    IOCTL_STORAGE_MEDIA_REMOVAL, IOCTL_STORAGE_EJECT_MEDIA = 0x002D4804, 0x002D4808
+    handle = k32.CreateFileW(f"\\\\.\\{mount[0]}:", GENERIC_RW, SHARE_RW, None, OPEN_EXISTING, 0, None)
+    if handle in (None, wintypes.HANDLE(-1).value):
+        return False
+    ret = wintypes.DWORD()
+
+    def ioctl(code: int, buf=None, size: int = 0) -> bool:
+        return bool(k32.DeviceIoControl(handle, code, buf, size, None, 0, ctypes.byref(ret), None))
+
+    try:
+        k32.FlushFileBuffers(handle)
+        for _ in range(10):                       # Explorer/indexer may hold it briefly
+            if ioctl(FSCTL_LOCK_VOLUME):
+                break
+            time.sleep(0.5)
+        else:
+            return False
+        if not ioctl(FSCTL_DISMOUNT_VOLUME):
+            return False
+        allow = ctypes.c_bool(False)              # PREVENT_MEDIA_REMOVAL{FALSE}
+        ioctl(IOCTL_STORAGE_MEDIA_REMOVAL, ctypes.byref(allow), 1)
+        ioctl(IOCTL_STORAGE_EJECT_MEDIA)          # card readers may not support it; dismount suffices
+        return True
+    finally:
+        k32.CloseHandle(handle)
+
+
+# ------------------------------------------------------------------- macOS
+
+def _format_macos(disk: Disk, log: list[str]) -> Outcome:
+    log.append(f"diskutil eraseDisk FAT32 {VOLUME_LABEL} MBRFormat {disk.id}")
+    proc = subprocess.run(["diskutil", "eraseDisk", "FAT32", VOLUME_LABEL, "MBRFormat", disk.id],
+                          capture_output=True, text=True, timeout=600)
+    log += [l for l in proc.stdout.splitlines() if l.strip()]
+    if proc.returncode != 0:
+        return Outcome(False, "Formatting failed: " + (proc.stderr.strip() or proc.stdout.strip()[-200:])
+                       + " (is the card's write-protect switch on?)", log=log)
+    part = f"{disk.id}s1"
+    for _ in range(20):   # wait for the volume to mount
+        info = plistlib.loads(subprocess.run(["diskutil", "info", "-plist", part], capture_output=True).stdout or b"<plist><dict/></plist>")
+        if info.get("MountPoint"):
+            return Outcome(True, "Formatted FAT32 (MBR).", info["MountPoint"], log)
+        time.sleep(0.5)
+    return Outcome(False, "Formatted, but the card did not mount.", log=log)
+
+
+def _eject_macos(disk_id: str) -> bool:
+    return subprocess.run(["diskutil", "eject", disk_id], capture_output=True, timeout=60).returncode == 0
+
+
+# ------------------------------------------------------------------ common
+
+def write_env(mount: str, env: EnvConfig) -> Outcome:
+    """Write ENV.TXT (8.3 name, LF, no BOM), keep other files (buffered data), read back."""
+    problems = [i.text for i in env.problems() if i.level == "error"]
+    if problems:
+        return Outcome(False, "Settings are not valid: " + " ".join(problems))
+    root = Path(mount)
+    if not root.is_dir():
+        return Outcome(False, f"Card not found at {mount}.")
+    old = find_case_insensitive(root, ENV_NAME)
+    if old is not None and old.name != ENV_NAME:
+        old.unlink()                                   # replace env.txt / Env.txt variants
+    target = root / ENV_NAME
+    data = env.render()
+    with open(target, "wb") as fh:
+        fh.write(data)
+        fh.flush()
+        os.fsync(fh.fileno())
+    if target.read_bytes() != data:
+        return Outcome(False, "ENV.TXT read-back does not match - the card may be faulty.")
+    check = parse_env(target.read_bytes())
+    if not check.ok:
+        return Outcome(False, "ENV.TXT was written but does not validate: "
+                       + " ".join(i.text for i in check.issues if i.level == "error"))
+    return Outcome(True, f"ENV.TXT written and verified on {mount}.", mount)
+
+
+def format_and_write(disk: Disk, env: EnvConfig, eject_card: bool = True) -> Outcome:
+    problems = [i.text for i in env.problems() if i.level == "error"]
+    if problems:
+        return Outcome(False, "Settings are not valid: " + " ".join(problems))
+    log: list[str] = []
+    if sys.platform == "win32":
+        fmt = _format_windows(disk, log)
+    elif sys.platform == "darwin":
+        fmt = _format_macos(disk, log)
+    else:
+        return Outcome(False, "SD provisioning is supported on Windows and macOS only.")
+    if not fmt.ok:
+        return fmt
+    wr = write_env(fmt.mount, env)
+    log.append(wr.message)
+    if not wr.ok:
+        return Outcome(False, wr.message, fmt.mount, log)
+    if eject_card:
+        log.append("Card ejected - you can remove it." if eject(fmt.mount, disk) else
+                   "Could not eject the card automatically - use 'Safely remove' before pulling it out.")
+    return Outcome(True, "Card ready: formatted FAT32 and ENV.TXT verified.", fmt.mount, log)
+
+
+def eject(mount: str, disk: Disk | None = None) -> bool:
+    """True if the card was dismounted and can be pulled out safely."""
+    if sys.platform == "win32":
+        return _eject_windows(mount)
+    if sys.platform == "darwin" and disk is not None:
+        return _eject_macos(disk.id)
+    return False
+
+
+def check_card(mount: str, filesystem: str = "") -> CardReport:
+    """What the box would find on this card (values masked in the UI)."""
+    root = Path(mount)
+    problems: list[str] = []
+    fs = filesystem.upper()
+    if fs and "FAT32" not in fs and fs not in ("FAT", "MS-DOS FAT32", "MSDOS"):
+        problems.append(f"File system is {filesystem}; the box needs FAT32 - re-format the card.")
+    env_file = find_case_insensitive(root, ENV_NAME)
+    env = parse_env(env_file.read_bytes()) if env_file else None
+    if env_file is None:
+        problems.append("No ENV.TXT on the card - the box stops at start-up (white LED).")
+    elif len(env_file.name.split(".")[0]) > 8:
+        problems.append("ENV.TXT has a long name variant; use exactly ENV.TXT.")
+    buf = find_case_insensitive(root, BUFFER_NAME)
+    lines = None
+    if buf is not None:
+        with open(buf, "rb") as fh:
+            lines = sum(1 for ln in fh if ln.strip())
+    return CardReport(mount, filesystem, env, lines, problems)