commit f6b271a926d02a3d7e13013a98f13e107cd82d16
Author: Konstantin Passig PC <2002erdi@gmail.com>
Date:   Tue Aug 25 15:09:18 2026 +0200

    Add yt-downloader: single-URL YouTube downloads through an isolated Mullvad WireGuard tunnel

diff --git a/.gitignore b/.gitignore
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+++ b/.gitignore
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+__pycache__/
+*.py[cod]
+*.egg-info/
+dist/
+build/
+.env
\ No newline at end of file
diff --git a/README.md b/README.md
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+++ b/README.md
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+# yt-downloader
+
+Download a single YouTube video through an **isolated Mullvad WireGuard tunnel**.
+
+Built as the video equivalent of [music-gatherer](https://github.com/anomalyco/music_gatherer)'s
+download phase: the only thing that talks to YouTube is the `download` command, and when a
+WireGuard config is configured it re-runs itself inside a dedicated network namespace whose
+only egress is the tunnel — so YouTube never sees your home IP. Everything else on your
+machine stays on the normal network.
+
+## Install
+
+```bash
+pip install -e .
+```
+
+Requires `yt-dlp` (pulled in automatically) and `ffmpeg` (used to mux separate
+video + audio streams into a single file).
+
+## Usage
+
+```bash
+yt-downloader init                 # write a starter config
+yt-downloader download <url>       # download one video (auto-wraps into the VPN)
+yt-downloader vpn up               # create the namespace + bring the tunnel up (sudo)
+yt-downloader vpn status           # handshake time, routes, DNS
+yt-downloader vpn down             # tear it all down
+```
+
+Download options:
+
+```bash
+yt-downloader download <url> -q 720                 # quality preset
+yt-downloader download <url> -q best                # best video+audio (default)
+yt-downloader download <url> -q audio               # audio only (no muxing needed)
+yt-downloader download <url> -q 1080 -o ~/Videos    # custom output dir
+yt-downloader download <url> -f 'bestvideo[height<=480]+bestaudio'   # raw yt-dlp format
+```
+
+Quality presets: `best`, `1080`, `720`, `480`, `audio`. The `-f/--format` flag takes any
+yt-dlp format string and overrides the preset.
+
+## Downloads through a Mullvad VPN
+
+By default downloads go through your normal connection. To route **only the yt-dlp
+traffic** through a WireGuard (Mullvad) tunnel, give the tool a WireGuard config:
+
+```toml
+[vpn]
+wireguard = "~/.config/yt-downloader/mullvad.conf"   # Mullvad .conf
+# namespace = "mullvad"   # optional: network namespace name
+# interface = "mv0"       # optional: WireGuard interface name
+```
+
+When set, `yt-downloader download` re-runs itself inside a dedicated **network namespace**
+whose only egress is the WireGuard tunnel. The namespace has no fallback route, so a dead
+tunnel means a failed download, never a leak. Bring-up is automatic (`ensure_up`); use
+`yt-downloader vpn up/down/status` to manage it by hand.
+
+It uses a Mullvad `.conf` (`[Interface]` + `[Peer]`), which you get from mullvad.net; the
+private key is copied into `/etc/wireguard/mv0.conf`.
+
+Requirements: Linux, `wireguard-tools` + `iproute2`, and `sudo`. Interactive runs prompt for
+the sudo password once; for unattended runs add passwordless sudo entries:
+
+```
+# /etc/sudoers.d/yt-downloader   (run: sudo visudo -f /etc/sudoers.d/yt-downloader)
+magerbeton ALL=(root) NOPASSWD: /usr/bin/ip, /usr/bin/wg, /usr/bin/wg-quick, \
+  /usr/sbin/iptables, /usr/sbin/sysctl, /bin/mkdir, /bin/rm, /bin/chmod, /bin/sh
+```
+
+The download process drops back to your user inside the namespace, so downloaded files stay
+owned by you.
+
+## Bot-check mitigation
+
+YouTube sometimes challenges downloads. Like music-gatherer, you can pass your browser
+cookies to yt-dlp:
+
+```toml
+[download]
+# cookies_file = "/path/to/cookies.txt"
+# cookies_from_browser = "firefox"   # e.g. chromium, firefox, safari
+```
+
+## Configuration
+
+See `yt_downloader.toml` after `init` for the full template (`~/.config/yt-downloader/`).
+
+```toml
+[download]
+out = "~/Videos/yt-downloader"   # where videos land
+quality = "best"                 # best | 1080 | 720 | 480 | audio
+# format = ""                    # raw yt-dlp -f string, overrides quality
+
+[vpn]
+# wireguard = "~/.config/yt-downloader/mullvad.conf"
+# namespace = "mullvad"
+# interface = "mv0"
+```
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diff --git a/pyproject.toml b/pyproject.toml
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--- /dev/null
+++ b/pyproject.toml
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+[build-system]
+requires = ["setuptools>=68"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "yt-downloader"
+version = "0.1.0"
+description = "Download YouTube videos through an isolated Mullvad WireGuard tunnel."
+requires-python = ">=3.10"
+dependencies = [
+    "yt-dlp>=2024.1.1",
+]
+
+[project.scripts]
+yt-downloader = "yt_downloader.cli:main"
+
+[tool.setuptools.packages.find]
+include = ["yt_downloader*"]
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diff --git a/yt_downloader/__init__.py b/yt_downloader/__init__.py
new file mode 100644
index 0000000..bd1b74c
--- /dev/null
+++ b/yt_downloader/__init__.py
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+"""yt_downloader - download YouTube videos through an isolated Mullvad tunnel."""
+
+__version__ = "0.1.0"
\ No newline at end of file
diff --git a/yt_downloader/__main__.py b/yt_downloader/__main__.py
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index 0000000..187e7c5
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+++ b/yt_downloader/__main__.py
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+import sys
+
+from .cli import main
+
+if __name__ == "__main__":
+    sys.exit(main())
\ No newline at end of file
diff --git a/yt_downloader/cli.py b/yt_downloader/cli.py
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+++ b/yt_downloader/cli.py
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+"""Command-line interface for yt-downloader."""
+
+from __future__ import annotations
+
+import argparse
+import logging
+import os
+import sys
+from pathlib import Path
+
+from . import __version__, vpn
+from .config import Config, QUALITY_PRESETS, default_config_path, load_config, write_default_config
+from .downloader import cookie_opts, download_video
+
+
+def log_setup(verbose: bool) -> None:
+    level = logging.DEBUG if verbose else logging.INFO
+    logging.basicConfig(
+        level=level,
+        format="%(levelname)-7s %(message)s",
+        stream=sys.stderr,
+    )
+
+
+# -- commands ------------------------------------------------------------
+
+def cmd_init(args: argparse.Namespace) -> int:
+    path = Path(args.config)
+    if path.exists():
+        logging.error("Config already exists: %s", path)
+        return 1
+    write_default_config(path)
+    print(f"Wrote config to {path}")
+    print("Edit it, then run: yt-downloader download <url>")
+    return 0
+
+
+def _download_argv(args: argparse.Namespace) -> list[str]:
+    """Rebuild the `download` argv for the VPN-wrapped subprocess."""
+    argv = ["download"]
+    if getattr(args, "config", None):
+        argv += ["--config", str(args.config)]
+    argv += [args.url]
+    if getattr(args, "quality", None):
+        argv += ["--quality", args.quality]
+    if getattr(args, "format", None):
+        argv += ["--format", args.format]
+    if getattr(args, "output", None):
+        argv += ["--output", str(args.output)]
+    return argv
+
+
+def cmd_download(args: argparse.Namespace) -> int:
+    cfg = load_config(args.config)
+    if (
+        not args.dry_run
+        and vpn.configured(cfg)
+        and not os.environ.get(vpn.INNER_ENV)
+    ):
+        try:
+            return vpn.run_download_in_ns(cfg, _download_argv(args))
+        except RuntimeError as exc:
+            logging.error("%s", exc)
+            return 1
+    if args.dry_run:
+        print(f"[dry] would download {args.url}")
+        return 0
+
+    quality = args.quality or cfg.quality
+    format_override = args.format or cfg.format_override
+    out_dir = Path(args.output) if args.output else cfg.out_dir
+    extra = cookie_opts(cfg)
+
+    print(f"downloading: {args.url} (quality={quality}, out={out_dir.expanduser()})")
+    path = download_video(args.url, out_dir, quality, format_override, extra)
+    if not path:
+        logging.error("download failed: %s", args.url)
+        return 1
+    print(f"saved: {path}")
+    return 0
+
+
+def cmd_vpn(args: argparse.Namespace) -> int:
+    cfg = load_config(args.config)
+    try:
+        if args.vpn_command == "up":
+            if vpn.is_up(cfg):
+                print("tunnel already up")
+            else:
+                vpn.up(cfg)
+                print("tunnel up")
+        elif args.vpn_command == "down":
+            vpn.down(cfg)
+            print("tunnel down")
+        elif args.vpn_command == "status":
+            print(vpn.status_text(cfg))
+    except RuntimeError as exc:
+        logging.error("%s", exc)
+        return 1
+    return 0
+
+
+# -- entry point ---------------------------------------------------------
+
+def build_parser() -> argparse.ArgumentParser:
+    parser = argparse.ArgumentParser(
+        prog="yt-downloader",
+        description="Download a single YouTube video through an isolated "
+                    "Mullvad WireGuard tunnel (network namespace).",
+    )
+    parser.add_argument("--version", action="version", version=__version__)
+    parser.add_argument(
+        "--config", "-c", type=str, default=str(default_config_path()),
+        help="path to config TOML",
+    )
+    parser.add_argument("-v", "--verbose", action="store_true", help="debug logging")
+
+    sub = parser.add_subparsers(dest="command", required=True)
+
+    sub.add_parser("init", help="write a starter config file")
+
+    p_dl = sub.add_parser("download", help="download a single YouTube video")
+    p_dl.add_argument("url", help="YouTube video URL")
+    p_dl.add_argument(
+        "-q", "--quality", choices=QUALITY_PRESETS, default=None,
+        help="video quality preset (default from config)",
+    )
+    p_dl.add_argument(
+        "-f", "--format", default=None,
+        help="raw yt-dlp format string, overrides --quality",
+    )
+    p_dl.add_argument(
+        "-o", "--output", type=Path, default=None,
+        help="output directory (default from config)",
+    )
+    p_dl.add_argument(
+        "--dry-run", action="store_true",
+        help="plan only: don't set up the tunnel and don't download",
+    )
+
+    p_vpn = sub.add_parser("vpn", help="manage the isolated Mullvad tunnel used by downloads")
+    vsub = p_vpn.add_subparsers(dest="vpn_command", required=True)
+    vsub.add_parser("up", help="create the tunnel namespace and bring WireGuard up")
+    vsub.add_parser("down", help="tear the tunnel namespace down")
+    vsub.add_parser("status", help="show tunnel state")
+
+    return parser
+
+
+def main(argv: list[str] | None = None) -> int:
+    parser = build_parser()
+    args = parser.parse_args(argv)
+    log_setup(args.verbose)
+    if args.command == "init":
+        args.config = args.config if args.config else str(default_config_path())
+        return cmd_init(args)
+    try:
+        if args.command == "download":
+            return cmd_download(args)
+        if args.command == "vpn":
+            return cmd_vpn(args)
+    except FileNotFoundError as exc:
+        logging.error("%s", exc)
+        return 1
+    parser.error(f"unknown command {args.command!r}")
+    return 2
+
+
+if __name__ == "__main__":
+    sys.exit(main())
\ No newline at end of file
diff --git a/yt_downloader/config.py b/yt_downloader/config.py
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+++ b/yt_downloader/config.py
@@ -0,0 +1,114 @@
+"""Configuration loading and defaults."""
+
+from __future__ import annotations
+
+import os
+import tomllib
+from pathlib import Path
+from typing import Any, Optional
+
+DEFAULT_CONFIG_NAME = "yt_downloader.toml"
+QUALITY_PRESETS = ("best", "1080", "720", "480", "audio")
+
+
+def default_config_path() -> Path:
+    xdg = os.environ.get("XDG_CONFIG_HOME")
+    base = Path(xdg) if xdg else Path.home() / ".config"
+    return base / "yt-downloader" / DEFAULT_CONFIG_NAME
+
+
+def _as_bool(value: Any, default: bool) -> bool:
+    if value is None:
+        return default
+    if isinstance(value, bool):
+        return value
+    return str(value).strip().lower() in ("1", "true", "yes", "on")
+
+
+class Config:
+    """Thin wrapper around the parsed TOML config."""
+
+    def __init__(self, data: dict, path: Path):
+        self._data = data
+        self.path = path
+
+    # -- download --------------------------------------------------------
+    @property
+    def out_dir(self) -> Path:
+        return Path(self._data.get("download", {}).get("out", "./videos"))
+
+    @property
+    def quality(self) -> str:
+        q = str(self._data.get("download", {}).get("quality", "best")).lower()
+        return q if q in QUALITY_PRESETS else "best"
+
+    @property
+    def format_override(self) -> Optional[str]:
+        return self._data.get("download", {}).get("format")
+
+    @property
+    def cookies_file(self) -> Optional[str]:
+        return self._data.get("download", {}).get("cookies_file")
+
+    @property
+    def cookies_from_browser(self) -> Optional[str]:
+        return self._data.get("download", {}).get("cookies_from_browser")
+
+    # -- vpn ------------------------------------------------------------
+    @property
+    def vpn_wireguard(self) -> Optional[str]:
+        return self._data.get("vpn", {}).get("wireguard")
+
+    @property
+    def vpn_namespace(self) -> Optional[str]:
+        return self._data.get("vpn", {}).get("namespace")
+
+    @property
+    def vpn_interface(self) -> Optional[str]:
+        return self._data.get("vpn", {}).get("interface")
+
+    # -- misc -----------------------------------------------------------
+    @property
+    def dry_run(self) -> bool:
+        return _as_bool(self._data.get("global", {}).get("dry_run", False), False)
+
+
+def load_config(path: Optional[Path | str] = None) -> Config:
+    if path is None:
+        path = default_config_path()
+    path = Path(path)
+    if not path.exists():
+        raise FileNotFoundError(
+            f"Config not found at {path}. Run 'yt-downloader init' first."
+        )
+    with open(path, "rb") as fh:
+        data = tomllib.load(fh)
+    return Config(data, path)
+
+
+def write_default_config(path: Path) -> None:
+    path.parent.mkdir(parents=True, exist_ok=True)
+    template = """\
+# yt-downloader configuration
+
+[global]
+dry_run = false                  # when true: plan only, touch nothing
+
+[download]
+out = "~/Videos/yt-downloader"   # where videos land
+quality = "best"                 # best | 1080 | 720 | 480 | audio
+# format = ""                    # raw yt-dlp -f string, overrides quality
+# cookies_file = "/path/to/cookies.txt"      # pass your browser cookies (best
+# cookies_from_browser = "firefox"           # protection against bot checks;
+#                                            # e.g. chromium, firefox, safari)
+
+[vpn]
+# wireguard = "~/.config/yt-downloader/mullvad.conf"
+#                                # optional: path to a WireGuard (Mullvad) .conf.
+#                                # When set, `download` runs inside a dedicated
+#                                # network namespace so ONLY yt-dlp traffic goes
+#                                # through the VPN. Requires sudo + wireguard-tools.
+# namespace = "mullvad"          # optional: network namespace name
+# interface = "mv0"              # optional: WireGuard interface name
+"""
+    path.write_text(template)
\ No newline at end of file
diff --git a/yt_downloader/downloader.py b/yt_downloader/downloader.py
new file mode 100644
index 0000000..60c0e78
--- /dev/null
+++ b/yt_downloader/downloader.py
@@ -0,0 +1,86 @@
+"""yt-dlp integration: download a single YouTube video (or its audio)."""
+
+from __future__ import annotations
+
+import logging
+from pathlib import Path
+from typing import Optional
+
+import yt_dlp
+
+log = logging.getLogger(__name__)
+
+_BASE_OPTS = {
+    "quiet": True,
+    "no_warnings": True,
+    "noplaylist": True,
+    "ignoreerrors": True,
+    "no_color": True,
+}
+
+# named presets -> yt-dlp format strings. bestvideo+bestaudio requires ffmpeg
+# to mux; the trailing /best fallbacks cover formats without a separate stream.
+QUALITY_FORMATS = {
+    "best": "bestvideo+bestaudio/best",
+    "1080": "bestvideo[height<=1080]+bestaudio/best[height<=1080]",
+    "720": "bestvideo[height<=720]+bestaudio/best[height<=720]",
+    "480": "bestvideo[height<=480]+bestaudio/best[height<=480]",
+    "audio": "bestaudio/best",
+}
+
+# suffixes yt-dlp leaves behind while downloading / on interrupted runs
+_INCOMPLETE = (".part", ".ytdl", ".tmp")
+
+
+def cookie_opts(cfg) -> dict:
+    """yt-dlp options for browser cookies (bot-check mitigation)."""
+    opts: dict = {}
+    if cfg.cookies_from_browser:
+        opts["cookiesfrombrowser"] = (cfg.cookies_from_browser,)
+    elif cfg.cookies_file:
+        opts["cookiefile"] = cfg.cookies_file
+    return opts
+
+
+def _select_format(quality: str, format_override: Optional[str]) -> str:
+    if format_override:
+        return format_override
+    return QUALITY_FORMATS.get(quality, QUALITY_FORMATS["best"])
+
+
+def download_video(
+    url: str,
+    out_dir: Path,
+    quality: str = "best",
+    format_override: Optional[str] = None,
+    extra_opts: dict | None = None,
+) -> Optional[Path]:
+    """Download a single video into out_dir. Returns the resulting file path."""
+    out_dir = out_dir.expanduser()
+    out_dir.mkdir(parents=True, exist_ok=True)
+    fmt = _select_format(quality, format_override)
+    opts = {
+        **_BASE_OPTS,
+        **(extra_opts or {}),
+        "format": fmt,
+        "outtmpl": str(out_dir / "%(title).150B [%(id)s].%(ext)s"),
+        "nocheckcertificate": True,
+    }
+    if quality != "audio" and not format_override:
+        opts["merge_output_format"] = "mp4"
+    try:
+        with yt_dlp.YoutubeDL(opts) as ydl:
+            info = ydl.extract_info(url, download=True)
+        if info is None:
+            return None
+        actual_id = info.get("id")
+        if not actual_id:
+            return None
+        marker = f" [{actual_id}]."
+        for f in out_dir.iterdir():
+            if f.is_file() and marker in f.name and f.suffix.lower() not in _INCOMPLETE:
+                return f
+    except Exception as exc:  # noqa: BLE001
+        log.warning("Download failed for %s: %s", url, exc)
+        return None
+    return None
\ No newline at end of file
diff --git a/yt_downloader/vpn.py b/yt_downloader/vpn.py
new file mode 100644
index 0000000..e99faeb
--- /dev/null
+++ b/yt_downloader/vpn.py
@@ -0,0 +1,226 @@
+"""Isolated Mullvad WireGuard tunnel for the yt-dlp download phase.
+
+The download phase is the only place yt-downloader talks to YouTube. When a
+WireGuard (Mullvad) config is configured, ``yt-downloader download`` re-runs
+itself inside a dedicated network namespace whose only egress is the WireGuard
+tunnel, so YouTube traffic never leaves through the normal network.
+
+Layout inside the namespace:
+
+    +-----------+   veth   +--------------------------------------+
+    | host      | eth0     | netns "mullvad"                      |
+    | veth-mv0  | 10.66..2 |   mv0 (WireGuard)  <- default route  |
+    | 10.66..1  +----------+   DNS -> Mullvad (through tunnel)    |
+    +-----------+          +--------------------------------------+
+
+The namespace has no fallback egress: if the tunnel is down the default route
+(via mv0) is dead, so traffic is dropped rather than leaked onto the host's
+network.
+
+Privileged steps are delegated to ``sudo``. sudo caches its credential, so an
+interactive run prompts once; unattended runs need the passwordless sudoers
+entries described in the README.
+"""
+
+from __future__ import annotations
+
+import configparser
+import getpass
+import logging
+import re
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+log = logging.getLogger(__name__)
+
+# host <-> namespace point-to-point veth link (a /30)
+_LINK_GUEST = "eth0"
+_HOST_ADDR = "10.66.66.1/30"
+_GUEST_ADDR = "10.66.66.2/30"
+_GUEST_NET = "10.66.66.0/30"
+_GUEST_GW = "10.66.66.1"
+FALLBACK_DNS = "10.64.0.1"  # Mullvad DNS
+
+# env var set on the inner re-run so it doesn't wrap itself again
+INNER_ENV = "YTDL_VPN"
+
+
+# -- configuration helpers ------------------------------------------------
+
+def configured(cfg) -> bool:
+    return bool(getattr(cfg, "vpn_wireguard", None))
+
+
+def netns_name(cfg) -> str:
+    return getattr(cfg, "vpn_namespace", None) or "mullvad"
+
+
+def iface_name(cfg) -> str:
+    return getattr(cfg, "vpn_interface", None) or "mv0"
+
+
+def conf_path(cfg) -> Path:
+    return Path(cfg.vpn_wireguard).expanduser()
+
+
+def _host_link(iface: str) -> str:
+    return f"veth-{iface}"[:15]
+
+
+def parse_conf(cfg) -> dict:
+    """Read [Interface] / [Peer] from the WireGuard config."""
+    path = conf_path(cfg)
+    if not path.exists():
+        raise FileNotFoundError(
+            f"WireGuard config not found: {path} "
+            "(set [vpn] wireguard or place the Mullvad .conf there)"
+        )
+    parser = configparser.ConfigParser(interpolation=None)
+    try:
+        parser.read(path)
+    except configparser.Error as exc:
+        raise ValueError(f"{path}: cannot parse WireGuard config: {exc}") from exc
+    if not parser.has_section("Interface") or not parser.has_section("Peer"):
+        raise ValueError(f"{path}: expected [Interface] and [Peer] sections")
+    interface = dict(parser.items("Interface"))
+    peer = dict(parser.items("Peer"))
+    dns = [
+        part.strip()
+        for part in re.split(r"[\s,]+", interface.get("dns", "").strip())
+        if part.strip()
+    ]
+    return {
+        "interface": interface,
+        "peer": peer,
+        "dns": dns,
+        "endpoint": peer.get("endpoint", "").strip(),
+    }
+
+
+def _strip_dns(path: Path) -> str:
+    lines = [ln for ln in path.read_text(encoding="utf-8").splitlines()
+             if not re.match(r"\s*DNS\s*=", ln)]
+    return "\n".join(lines) + "\n"
+
+
+# -- low-level sudo plumbing ---------------------------------------------
+
+def _run(cmd: list[str], check: bool = True, input: bytes | None = None) -> subprocess.CompletedProcess:
+    proc = subprocess.run(cmd, input=input, check=False)
+    if check and proc.returncode != 0:
+        raise RuntimeError(f"command failed (exit {proc.returncode}): {' '.join(cmd)}")
+    return proc
+
+
+def _sudo(args: list[str], check: bool = True, input: bytes | None = None) -> subprocess.CompletedProcess:
+    return _run(["sudo", *args], check=check, input=input)
+
+
+def _sudo_out(args: list[str]) -> tuple[int, str]:
+    proc = subprocess.run(["sudo", *args], capture_output=True, text=True)
+    return proc.returncode, (proc.stdout + proc.stderr).strip()
+
+
+# -- lifecycle -------------------------------------------------------------
+
+def is_up(cfg) -> bool:
+    ns, iface = netns_name(cfg), iface_name(cfg)
+    rc, out = _sudo_out(["ip", "netns", "exec", ns, "wg", "show", iface])
+    return rc == 0 and "no such device" not in out.lower()
+
+
+def up(cfg) -> None:
+    ns, iface = netns_name(cfg), iface_name(cfg)
+    host_link = _host_link(iface)
+    for tool in ("ip", "wg", "wg-quick"):
+        if not shutil.which(tool):
+            raise RuntimeError(
+                f"required tool not found: {tool!r} (install wireguard-tools / iproute2)"
+            )
+    info = parse_conf(cfg)
+    dns_servers = info["dns"] or [FALLBACK_DNS]
+
+    # 1. namespace DNS — `ip netns exec` binds this over /etc/resolv.conf
+    _sudo(["mkdir", "-p", f"/etc/netns/{ns}"])
+    resolv = "".join(f"nameserver {d}\n" for d in dns_servers)
+    _sudo(["sh", "-c", f"cat > /etc/netns/{ns}/resolv.conf"], input=resolv.encode())
+
+    # 2. namespace + host <-> namespace veth link
+    _sudo(["ip", "netns", "add", ns], check=False)
+    _sudo(["ip", "link", "add", host_link, "type", "veth",
+           "peer", "name", _LINK_GUEST, "netns", ns], check=False)
+    _sudo(["ip", "link", "set", host_link, "up"])
+    _sudo(["ip", "addr", "add", _HOST_ADDR, "dev", host_link], check=False)
+    _sudo(["ip", "netns", "exec", ns, "ip", "link", "set", "lo", "up"])
+    _sudo(["ip", "netns", "exec", ns, "ip", "addr", "add", _GUEST_ADDR, "dev", _LINK_GUEST], check=False)
+    _sudo(["ip", "netns", "exec", ns, "ip", "link", "set", _LINK_GUEST, "up"])
+    # pre-tunnel default route so the WireGuard endpoint is reachable while the
+    # tunnel is still down; wg-quick replaces it with the tunnel default below
+    _sudo(["ip", "netns", "exec", ns, "ip", "route", "add", "default", "via", _GUEST_GW], check=False)
+
+    # 3. host forwards + NATs the namespace so it can reach the wg endpoint
+    _sudo(["sysctl", "-w", "net.ipv4.ip_forward=1"])
+    _sudo(["iptables", "-t", "nat", "-C", "POSTROUTING",
+           "-s", _GUEST_NET, "-j", "MASQUERADE"], check=False)
+    _sudo(["iptables", "-t", "nat", "-A", "POSTROUTING",
+           "-s", _GUEST_NET, "-j", "MASQUERADE"])
+
+    # 4. normalized wg config (DNS handled above, not by wg-quick) + tunnel up
+    cleaned = _strip_dns(conf_path(cfg))
+    _sudo(["sh", "-c", f"cat > /etc/wireguard/{iface}.conf"], input=cleaned.encode())
+    _sudo(["chmod", "600", f"/etc/wireguard/{iface}.conf"])
+    _sudo(["ip", "netns", "exec", ns, "wg-quick", "up", iface])
+
+    log.info("Mullvad tunnel up: namespace=%s interface=%s dns=%s",
+             ns, iface, ",".join(dns_servers))
+
+
+def down(cfg) -> None:
+    ns, iface = netns_name(cfg), iface_name(cfg)
+    host_link = _host_link(iface)
+    _sudo(["ip", "netns", "exec", ns, "wg-quick", "down", iface], check=False)
+    _sudo(["ip", "link", "del", host_link], check=False)
+    _sudo(["ip", "netns", "del", ns], check=False)
+    _sudo(["iptables", "-t", "nat", "-D", "POSTROUTING",
+           "-s", _GUEST_NET, "-j", "MASQUERADE"], check=False)
+    _sudo(["rm", "-f", f"/etc/wireguard/{iface}.conf"])
+    _sudo(["rm", "-rf", f"/etc/netns/{ns}"])
+
+
+def ensure_up(cfg) -> None:
+    if is_up(cfg):
+        return
+    log.info("Mullvad tunnel is down — bringing it up")
+    down(cfg)  # converge from any stale half-configured state
+    up(cfg)
+
+
+def status_text(cfg) -> str:
+    ns, iface = netns_name(cfg), iface_name(cfg)
+    rc, out = _sudo_out(["ip", "netns", "exec", ns, "wg", "show", iface])
+    if rc != 0:
+        return "tunnel: DOWN (namespace or WireGuard interface missing)"
+    lines = ["tunnel: UP", f"namespace : {ns}"]
+    lines.extend(line for line in out.splitlines())
+    _, route = _sudo_out(["ip", "netns", "exec", ns, "ip", "route", "show", "default"])
+    lines.append("default   : " + (route or "(none)"))
+    _, dns = _sudo_out(["cat", f"/etc/netns/{ns}/resolv.conf"])
+    lines.append("dns       : " + (dns.replace("\n", " ").strip() or "(none)"))
+    return "\n".join(lines)
+
+
+# -- running downloads inside the tunnel ----------------------------------
+
+def run_download_in_ns(cfg, argv: list[str]) -> int:
+    """Re-run ``yt-downloader download <argv>`` inside the tunnel namespace,
+    dropping back to the invoking user so downloaded files stay theirs."""
+    ensure_up(cfg)
+    ns = netns_name(cfg)
+    user = getpass.getuser()
+    cmd = [sys.executable, "-m", "yt_downloader", *argv]
+    wrapped = ["sudo", "ip", "netns", "exec", ns,
+               "sudo", "-u", user, "env", f"{INNER_ENV}=1", *cmd]
+    log.info("running download inside Mullvad namespace %r", ns)
+    return _run(wrapped, check=False).returncode
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