diff --git a/bot_bottle/cli/__init__.py b/bot_bottle/cli/__init__.py
index ae421fc..cf62f68 100644
--- a/bot_bottle/cli/__init__.py
+++ b/bot_bottle/cli/__init__.py
@@ -19,6 +19,7 @@ from .commit import cmd_commit
 from .edit import cmd_edit
 from .info import cmd_info
 from .init import cmd_init
+from .login import cmd_login
 from .resume import cmd_resume
 from .start import cmd_start
 from .supervise import cmd_supervise
@@ -33,6 +34,7 @@ COMMANDS = {
     "info": cmd_info,
     "init": cmd_init,
     "list": cmd_list,
+    "login": cmd_login,
     "resume": cmd_resume,
     "start": cmd_start,
     "supervise": cmd_supervise,
@@ -43,7 +45,7 @@ COMMANDS = {
 # the host (TAP pool, /dev/kvm, firecracker) and never opens the store, so
 # gating it on the schema breaks preflight on a fresh CI runner where stdin
 # isn't a TTY and the migration prompt can't be answered.
-NO_MIGRATION_COMMANDS = frozenset({"backend"})
+NO_MIGRATION_COMMANDS = frozenset({"backend", "login"})
 
 
 def usage() -> None:
@@ -56,6 +58,7 @@ def usage() -> None:
     sys.stderr.write("  info      print env, skills, and prompt details for a named agent\n")
     sys.stderr.write("  init      interactively create a new agent and add it to bot-bottle.json\n")
     sys.stderr.write("  list      list available agents or active containers\n")
+    sys.stderr.write("  login     register this host with a bot-bottle console\n")
     sys.stderr.write(
         "  resume    re-launch a bottle by its identity "
         "(continues state from PRD 0016)\n"
@@ -111,7 +114,3 @@ def main(argv: list[str] | None = None) -> int:
         return e.code if isinstance(e.code, int) else 1
     except KeyboardInterrupt:
         return 130
-
-
-if __name__ == "__main__":
-    sys.exit(main())
diff --git a/bot_bottle/cli/__main__.py b/bot_bottle/cli/__main__.py
new file mode 100644
index 0000000..3cf5f19
--- /dev/null
+++ b/bot_bottle/cli/__main__.py
@@ -0,0 +1,15 @@
+"""Entry point for `python -m bot_bottle.cli`.
+
+`cli.py` at the repo root is the usual way in; this makes the package
+runnable too, so the CLI works from an installed copy where there is no
+`cli.py` on disk to point at.
+"""
+
+from __future__ import annotations
+
+import sys
+
+from . import main
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/bot_bottle/cli/login.py b/bot_bottle/cli/login.py
new file mode 100644
index 0000000..3d00f17
--- /dev/null
+++ b/bot_bottle/cli/login.py
@@ -0,0 +1,168 @@
+"""bb login — register this host with a bot-bottle console.
+
+Opens a device-authorization flow against the target console, waits for the
+operator to approve, then writes access and refresh tokens to
+~/.bot-bottle/console.json (or $BOT_BOTTLE_ROOT/console.json).
+
+Usage:
+  bb login [--console-url URL] [--label LABEL]
+
+Flags:
+  --console-url URL   Target console URL (overrides BB_CONSOLE_URL env var)
+  --label LABEL       Host label shown in the console (default: hostname)
+"""
+
+from __future__ import annotations
+
+import json
+import os
+import socket
+import sys
+import tempfile
+import time
+import urllib.error
+import urllib.request
+from pathlib import Path
+from typing import Any
+
+from ..paths import bot_bottle_root
+
+_CONSOLE_URL_ENV = "BB_CONSOLE_URL"
+_POLL_SLEEP = 2  # seconds between polls; matches console's poll_interval default
+
+
+def _usage() -> None:
+    sys.stderr.write(
+        "usage: bb login [--console-url URL] [--label LABEL]\n"
+        "\n"
+        "Options:\n"
+        "  --console-url URL  Console base URL (or BB_CONSOLE_URL env var)\n"
+        "  --label LABEL      Host label shown in the console (default: hostname)\n"
+    )
+
+
+def _flag(argv: list[str], name: str) -> str | None:
+    for i, arg in enumerate(argv):
+        if arg == name and i + 1 < len(argv):
+            return argv[i + 1]
+        if arg.startswith(f"{name}="):
+            return arg[len(name) + 1:]
+    return None
+
+
+def _post(url: str, payload: dict[str, Any]) -> dict[str, Any]:
+    data = json.dumps(payload).encode()
+    req = urllib.request.Request(
+        url, data=data, headers={"Content-Type": "application/json"}
+    )
+    with urllib.request.urlopen(req, timeout=10) as resp:
+        return json.loads(resp.read())
+
+
+def _get(url: str) -> tuple[int, dict[str, Any]]:
+    req = urllib.request.Request(url)
+    try:
+        with urllib.request.urlopen(req, timeout=10) as resp:
+            return resp.status, json.loads(resp.read())
+    except urllib.error.HTTPError as e:
+        return e.code, {}
+
+
+def _save_credentials(
+    console_url: str, host_id: str, access_token: str, refresh_token: str
+) -> Path:
+    path = bot_bottle_root() / "console.json"
+    path.parent.mkdir(parents=True, exist_ok=True)
+    content = (
+        json.dumps(
+            {
+                "url": console_url,
+                "host_id": host_id,
+                "access_token": access_token,
+                "refresh_token": refresh_token,
+            },
+            indent=2,
+        )
+        + "\n"
+    )
+    fd, tmp_path_str = tempfile.mkstemp(dir=path.parent, prefix=".console-")
+    tmp = Path(tmp_path_str)
+    try:
+        tmp.chmod(0o600)
+        with os.fdopen(fd, "w") as f:
+            f.write(content)
+        os.replace(tmp, path)
+    except OSError:
+        try:
+            tmp.unlink()
+        except OSError:
+            pass
+        raise
+    return path
+
+
+def cmd_login(argv: list[str]) -> int:
+    if "--help" in argv or "-h" in argv:
+        _usage()
+        return 0
+
+    console_url = _flag(argv, "--console-url") or os.environ.get(_CONSOLE_URL_ENV)
+    if not console_url:
+        sys.stderr.write(
+            "bb login: --console-url or BB_CONSOLE_URL is required\n"
+        )
+        return 1
+    console_url = console_url.rstrip("/")
+
+    label = _flag(argv, "--label") or socket.gethostname()
+
+    try:
+        resp = _post(f"{console_url}/api/v1/hosts/authorize", {"label": label})
+    except (OSError, ValueError) as exc:
+        sys.stderr.write(f"bb login: failed to start authorization: {exc}\n")
+        return 1
+
+    device_code = resp["device_code"]
+    user_code = resp["user_code"]
+    expires_in = resp.get("expires_in", 300)
+    poll_sleep = max(1, min(int(resp.get("poll_interval", _POLL_SLEEP)), 60))
+
+    sys.stderr.write(
+        f"\nOpen this URL in your browser to authorize this host:\n\n"
+        f"  {console_url}/hosts/authorize?code={user_code}\n\n"
+        f"Waiting for approval"
+    )
+
+    deadline = time.monotonic() + expires_in
+    while time.monotonic() < deadline:
+        sys.stderr.write(".")
+        sys.stderr.flush()
+        time.sleep(poll_sleep)
+
+        try:
+            code, result = _get(
+                f"{console_url}/api/v1/hosts/authorize/{device_code}"
+            )
+        except (OSError, ValueError):
+            continue
+
+        if code == 410:
+            break
+
+        st = result.get("status")
+        if st == "approved":
+            sys.stderr.write("\n\nApproved.\n")
+            path = _save_credentials(
+                console_url,
+                result["host_id"],
+                result["access_token"],
+                result["refresh_token"],
+            )
+            sys.stderr.write(f"Credentials saved to {path}\n")
+            return 0
+        if st == "denied":
+            sys.stderr.write("\n\nDenied by operator.\n")
+            return 1
+
+    sys.stderr.write("\n\nAuthorization timed out.\n")
+    return 1
diff --git a/tests/unit/test_cli_login.py b/tests/unit/test_cli_login.py
new file mode 100644
index 0000000..0d4c13c
--- /dev/null
+++ b/tests/unit/test_cli_login.py
@@ -0,0 +1,268 @@
+"""Unit tests for bb login command."""
+
+from __future__ import annotations
+
+import json
+import os
+import tempfile
+import unittest
+import urllib.error
+from email.message import Message
+from typing import Any
+from unittest.mock import MagicMock, patch
+
+
+class TestFlagParsing(unittest.TestCase):
+    def test_console_url_flag(self) -> None:
+        from bot_bottle.cli.login import _flag
+        self.assertEqual(_flag(["--console-url", "http://x"], "--console-url"), "http://x")
+
+    def test_console_url_equals_form(self) -> None:
+        from bot_bottle.cli.login import _flag
+        self.assertEqual(
+            _flag(["--console-url=http://x"], "--console-url"), "http://x"
+        )
+
+    def test_label_flag(self) -> None:
+        from bot_bottle.cli.login import _flag
+        self.assertEqual(_flag(["--label", "my-mac"], "--label"), "my-mac")
+
+    def test_missing_flag_returns_none(self) -> None:
+        from bot_bottle.cli.login import _flag
+        self.assertIsNone(_flag([], "--console-url"))
+
+
+class TestHttpHelpers(unittest.TestCase):
+    def test_post_sends_json_and_decodes_response(self) -> None:
+        from bot_bottle.cli.login import _post
+
+        response = MagicMock()
+        response.__enter__.return_value.read.return_value = b'{"ok": true}'
+        with patch("urllib.request.urlopen", return_value=response) as urlopen:
+            self.assertEqual(
+                _post("http://console/start", {"label": "host"}), {"ok": True}
+            )
+
+        request = urlopen.call_args.args[0]
+        self.assertEqual(request.data, b'{"label": "host"}')
+        self.assertEqual(request.get_header("Content-type"), "application/json")
+
+    def test_get_decodes_success_response(self) -> None:
+        from bot_bottle.cli.login import _get
+
+        response = MagicMock()
+        response.__enter__.return_value.status = 200
+        response.__enter__.return_value.read.return_value = b'{"status": "pending"}'
+        with patch("urllib.request.urlopen", return_value=response):
+            self.assertEqual(
+                _get("http://console/status"), (200, {"status": "pending"})
+            )
+
+    def test_get_returns_http_error_status(self) -> None:
+        from bot_bottle.cli.login import _get
+
+        error = urllib.error.HTTPError(
+            "http://console/status", 410, "gone", Message(), None
+        )
+        with patch("urllib.request.urlopen", side_effect=error):
+            self.assertEqual(_get("http://console/status"), (410, {}))
+
+
+class TestSaveCredentials(unittest.TestCase):
+    def test_writes_json_and_sets_perms(self) -> None:
+        from bot_bottle.cli.login import _save_credentials
+
+        with tempfile.TemporaryDirectory() as tmp:
+            with patch.dict(os.environ, {"BOT_BOTTLE_ROOT": tmp}):
+                path = _save_credentials("http://c", "hid", "at", "rt")
+            self.assertTrue(path.exists())
+            data = json.loads(path.read_text())
+            self.assertEqual(data["url"], "http://c")
+            self.assertEqual(data["host_id"], "hid")
+            self.assertEqual(data["access_token"], "at")
+            self.assertEqual(data["refresh_token"], "rt")
+            self.assertEqual(oct(path.stat().st_mode & 0o777), oct(0o600))
+
+    def test_temp_file_is_private_before_replace(self) -> None:
+        """Temp file must be 0600 at the moment os.replace is called."""
+        from bot_bottle.cli.login import _save_credentials
+        from pathlib import Path as _Path
+
+        tmp_perms_at_replace: list[int] = []
+        real_replace = os.replace
+
+        def _spy_replace(
+            src: str | os.PathLike[str], dst: str | os.PathLike[str]
+        ) -> None:
+            tmp_perms_at_replace.append(_Path(src).stat().st_mode & 0o777)
+            real_replace(src, dst)
+
+        with tempfile.TemporaryDirectory() as tmp:
+            with patch.dict(os.environ, {"BOT_BOTTLE_ROOT": tmp}):
+                with patch("os.replace", side_effect=_spy_replace):
+                    path = _save_credentials("http://c", "hid", "at", "rt")
+                self.assertEqual(len(tmp_perms_at_replace), 1)
+                self.assertEqual(oct(tmp_perms_at_replace[0]), oct(0o600))
+                self.assertEqual(oct(path.stat().st_mode & 0o777), oct(0o600))
+
+    def test_cleanup_on_write_failure(self) -> None:
+        """Temp file is removed and no credentials remain if replace fails."""
+        from bot_bottle.cli.login import _save_credentials
+
+        with tempfile.TemporaryDirectory() as tmp:
+            with patch.dict(os.environ, {"BOT_BOTTLE_ROOT": tmp}):
+                with patch("os.replace", side_effect=OSError("disk full")):
+                    with self.assertRaises(OSError):
+                        _save_credentials("http://c", "hid", "at", "rt")
+            leftovers = [f for f in os.listdir(tmp) if f.startswith(".console-")]
+            self.assertEqual(leftovers, [])
+
+
+class TestCmdLoginMissingUrl(unittest.TestCase):
+    def test_help_returns_0(self) -> None:
+        from bot_bottle.cli.login import cmd_login
+
+        self.assertEqual(cmd_login(["--help"]), 0)
+
+    def test_returns_1_without_url(self) -> None:
+        from bot_bottle.cli.login import cmd_login
+        with patch.dict(os.environ, {}, clear=True):
+            os.environ.pop("BB_CONSOLE_URL", None)
+            result = cmd_login([])
+        self.assertEqual(result, 1)
+
+    def test_reads_env_var(self) -> None:
+        """Exits 1 (network error) not because of missing URL when env var is set."""
+        from bot_bottle.cli.login import cmd_login
+
+        def _fail_post(_url: str, _payload: dict[str, Any]) -> dict[str, Any]:
+            raise OSError("connection refused")
+
+        with tempfile.TemporaryDirectory() as tmp:
+            with patch.dict(
+                os.environ,
+                {
+                    "BB_CONSOLE_URL": "http://localhost:9999",
+                    "BOT_BOTTLE_ROOT": tmp,
+                },
+            ):
+                with patch("bot_bottle.cli.login._post", side_effect=_fail_post):
+                    result = cmd_login([])
+        self.assertEqual(result, 1)
+
+
+class TestCmdLoginFlow(unittest.TestCase):
+    def _run_with_mocks(
+        self, poll_responses: list[dict[str, Any]], tmp: str
+    ) -> int:
+        from bot_bottle.cli.login import cmd_login
+
+        start_resp = {
+            "device_code": "dc123",
+            "user_code": "ABC-DEF",
+            "expires_in": 300,
+            "poll_interval": 0,
+        }
+
+        poll_iter = iter(poll_responses)
+
+        def _fake_post(
+            _url: str, _payload: dict[str, Any]
+        ) -> dict[str, Any]:
+            return start_resp
+
+        def _fake_get(_url: str) -> tuple[int, dict[str, Any]]:
+            return 200, next(poll_iter, {"status": "pending"})
+
+        with patch.dict(os.environ, {"BOT_BOTTLE_ROOT": tmp}):
+            with patch("bot_bottle.cli.login._post", side_effect=_fake_post):
+                with patch("bot_bottle.cli.login._get", side_effect=_fake_get):
+                    with patch("time.sleep"):
+                        return cmd_login(["--console-url", "http://console"])
+
+    def test_approved_flow_returns_0(self) -> None:
+        approved = {
+            "status": "approved",
+            "host_id": "hid",
+            "access_token": "at",
+            "refresh_token": "rt",
+        }
+        with tempfile.TemporaryDirectory() as tmp:
+            result = self._run_with_mocks(
+                [{"status": "pending"}, approved], tmp
+            )
+            self.assertEqual(result, 0)
+            with open(os.path.join(tmp, "console.json"), encoding="utf-8") as f:
+                creds = json.loads(f.read())
+            self.assertEqual(creds["host_id"], "hid")
+
+    def test_denied_flow_returns_1(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            result = self._run_with_mocks([{"status": "denied"}], tmp)
+        self.assertEqual(result, 1)
+
+    def test_timeout_returns_1(self) -> None:
+        from bot_bottle.cli.login import cmd_login
+
+        start_resp = {
+            "device_code": "dc",
+            "user_code": "ZZZ-ZZZ",
+            "expires_in": 0,  # already expired; loop never runs
+            "poll_interval": 2,
+        }
+
+        with tempfile.TemporaryDirectory() as tmp:
+            with patch.dict(os.environ, {"BOT_BOTTLE_ROOT": tmp}):
+                with patch("bot_bottle.cli.login._post", return_value=start_resp):
+                    result = cmd_login(["--console-url", "http://console"])
+        self.assertEqual(result, 1)
+
+    def test_poll_interval_from_server_is_used(self) -> None:
+        """time.sleep must be called with the server-provided poll_interval."""
+        from bot_bottle.cli.login import cmd_login
+
+        server_interval = 7
+        start_resp = {
+            "device_code": "dc",
+            "user_code": "ABC-DEF",
+            "expires_in": 300,
+            "poll_interval": server_interval,
+        }
+        approved = {
+            "status": "approved",
+            "host_id": "hid",
+            "access_token": "at",
+            "refresh_token": "rt",
+        }
+        poll_iter = iter([{"status": "pending"}, approved])
+
+        def _fake_get(_url: str) -> tuple[int, dict[str, str]]:
+            return 200, next(poll_iter)
+
+        with tempfile.TemporaryDirectory() as tmp:
+            with patch.dict(os.environ, {"BOT_BOTTLE_ROOT": tmp}):
+                with patch("bot_bottle.cli.login._post", return_value=start_resp):
+                    with patch(
+                        "bot_bottle.cli.login._get", side_effect=_fake_get
+                    ):
+                        with patch("time.sleep") as mock_sleep:
+                            result = cmd_login(["--console-url", "http://console"])
+
+        self.assertEqual(result, 0)
+        self.assertTrue(mock_sleep.called)
+        for call in mock_sleep.call_args_list:
+            self.assertEqual(call.args[0], server_interval)
+
+
+class TestDispatcherRegistration(unittest.TestCase):
+    def test_login_in_commands(self) -> None:
+        from bot_bottle.cli import COMMANDS
+        self.assertIn("login", COMMANDS)
+
+    def test_login_in_no_migration(self) -> None:
+        from bot_bottle.cli import NO_MIGRATION_COMMANDS
+        self.assertIn("login", NO_MIGRATION_COMMANDS)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/unit/test_cli_module_entry.py b/tests/unit/test_cli_module_entry.py
new file mode 100644
index 0000000..2ff003b
--- /dev/null
+++ b/tests/unit/test_cli_module_entry.py
@@ -0,0 +1,40 @@
+"""The CLI package is runnable as `python -m bot_bottle.cli`."""
+
+from __future__ import annotations
+
+import subprocess
+import sys
+import unittest
+from pathlib import Path
+
+_REPO_ROOT = Path(__file__).resolve().parents[2]
+
+
+def _run(*args: str) -> subprocess.CompletedProcess[str]:
+    return subprocess.run(
+        [sys.executable, "-m", "bot_bottle.cli", *args],
+        cwd=_REPO_ROOT,
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+
+
+class TestModuleEntry(unittest.TestCase):
+    def test_help_exits_zero(self) -> None:
+        result = _run("--help")
+        self.assertEqual(result.returncode, 0, result.stderr)
+        self.assertIn("login", result.stderr)
+
+    def test_no_args_prints_usage(self) -> None:
+        # main() returns 2 with no command, matching the cli.py entry point.
+        self.assertEqual(_run().returncode, 2)
+
+    def test_subcommand_help_reaches_handler(self) -> None:
+        result = _run("login", "--help")
+        self.assertEqual(result.returncode, 0, result.stderr)
+        self.assertIn("--console-url", result.stderr)
+
+
+if __name__ == "__main__":
+    unittest.main()