firecracker status(): add binary and KVM readiness checks

Adds `_firecracker_binary_ok()` (runs `firecracker --version`) and
`_kvm_accessible()` (opens /dev/kvm, issues KVM_GET_API_VERSION ioctl)
and gates `status()` on both, so the launch preflight reports missing
binary or inaccessible KVM before the caller ever attempts a boot.

Regression tests in TestFirecrackerBinaryCheck, TestFirecrackerKvmCheck,
and TestFirecrackerStatusRuntime cover all branches. Updated the
pre-existing TestFirecrackerStatus fixture to also stub the two new
helpers so it still exercises only the tap-pool/nft logic it was
designed for.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/test.yml

@@ -103,14 +103,16 @@ jobs:
       - name: Install coverage
         run: python3 -m pip install --break-system-packages coverage
 
-      - name: Show environment
+      # Fail loudly if the backend this job promises isn't actually usable,
+      # rather than letting every test silently `unittest.skip` and the job
+      # go green on zero coverage. `backend status` prints a clear per-check
+      # summary (docker on PATH, daemon reachable) and exits non-zero when a
+      # prerequisite is missing — the same readiness check the skip guards
+      # gate on via `has_backend`.
+      - name: Preflight — Docker backend is ready
         run: |
           python3 --version
-          if command -v docker >/dev/null 2>&1; then
+          python3 cli.py backend status --backend=docker
-            docker version || true
-          else
-            echo "docker not on PATH — integration tests will skip"
-          fi
 
       - name: Run integration tests (docker) with coverage
         env:

bot_bottle/backend/__init__.py

@@ -33,6 +33,7 @@ backend field; the host picks.
 
 from __future__ import annotations
 
+import enum
 import os
 import shlex
 import sys
@@ -59,6 +60,12 @@ if TYPE_CHECKING:
     from .freeze import CommitCancelled, Freezer, get_freezer
 
 
+class BackendStatus(enum.IntEnum):
+    """Return codes for BottleBackend.status(). READY == 0 so callsites
+    can compare against 0 or the named constant interchangeably."""
+    READY = 0
+
+
 @dataclass(frozen=True)
 class BottleSpec:
     """CLI-supplied intent. Backend-agnostic — each backend's prepare
@@ -611,12 +618,18 @@ class BottleBackend(ABC, Generic[PlanT, CleanupT]):
 
     @classmethod
     @abstractmethod
-    def status(cls) -> int:
+    def status(cls, *, quiet: bool = False) -> int:
         """Report whether this backend's prerequisites are satisfied on
         the host — binaries, daemon reachability, network pool, range
-        conflicts, etc. Prints a human-readable summary; returns 0 when
+        conflicts, etc. Returns BackendStatus.READY (0) when the backend
-        the backend is ready to launch and non-zero when something is
+        is ready to launch and non-zero when something is missing.
-        missing. Invoked by `./cli.py backend status [--backend=…]`."""
+
+        When quiet=False (default) prints a human-readable summary to
+        stderr. When quiet=True returns the status code silently —
+        useful for cheap programmatic checks.
+
+        Invoked by `./cli.py backend status [--backend=…]` (quiet=False)
+        and by is_backend_ready() (caller-controlled)."""
 
     @classmethod
     @abstractmethod
@@ -811,6 +824,29 @@ def has_backend(name: str) -> bool:
     return backends[name].is_available()
 
 
+def is_backend_available(name: str) -> bool:
+    """Cheap availability check: is the backend's binary on PATH?
+
+    Suitable for cleanup enumeration and auto-selection — does NOT probe
+    the daemon or network pool. Use is_backend_ready() for a full
+    readiness check before launching tests."""
+    return has_backend(name)
+
+
+def is_backend_ready(name: str, *, quiet: bool = False) -> bool:
+    """Full readiness check: passes all of the backend's status() checks.
+
+    When quiet=False the backend prints diagnostic output explaining what
+    is missing — intended for test-suite guards that run at discovery time
+    so the operator sees a concrete failure reason for each skip.
+
+    Returns False for unknown backend names."""
+    backends = _get_backends()
+    if name not in backends:
+        return False
+    return backends[name].status(quiet=quiet) == BackendStatus.READY
+
+
 def enumerate_active_agents() -> list[ActiveAgent]:
     """All currently-running agents, across every available
     backend. Used by CLI `list active` and the dashboard's agents
@@ -835,6 +871,7 @@ def enumerate_active_agents() -> list[ActiveAgent]:
 
 __all__ = [
     "ActiveAgent",
+    "BackendStatus",
     "Bottle",
     "BottleBackend",
     "BottleCleanupPlan",
@@ -847,5 +884,7 @@ __all__ = [
     "get_bottle_backend",
     "get_freezer",
     "has_backend",
+    "is_backend_available",
+    "is_backend_ready",
     "known_backend_names",
 ]

bot_bottle/backend/docker/backend.py

@@ -20,7 +20,8 @@ infrastructure: CA install and git copy-in.
 from __future__ import annotations
 
 import shutil
-from contextlib import contextmanager
+import io
+from contextlib import contextmanager, redirect_stderr
 from pathlib import Path
 from typing import Generator, Sequence
 
@@ -60,8 +61,11 @@ class DockerBottleBackend(BottleBackend["DockerBottlePlan", "DockerBottleCleanup
         return _setup.setup()
 
     @classmethod
-    def status(cls) -> int:
+    def status(cls, *, quiet: bool = False) -> int:
         from . import setup as _setup
+        if quiet:
+            with redirect_stderr(io.StringIO()):
+                return _setup.status()
         return _setup.status()
 
     @classmethod

bot_bottle/backend/firecracker/backend.py

@@ -8,7 +8,8 @@ fail-closed nftables egress boundary. Selected by
 
 from __future__ import annotations
 
-from contextlib import contextmanager
+import io
+from contextlib import contextmanager, redirect_stderr
 from pathlib import Path
 from typing import Generator, Sequence
 
@@ -52,8 +53,11 @@ class FirecrackerBottleBackend(
         return _setup.setup()
 
     @classmethod
-    def status(cls) -> int:
+    def status(cls, *, quiet: bool = False) -> int:
         from . import setup as _setup
+        if quiet:
+            with redirect_stderr(io.StringIO()):
+                return _setup.status()
         return _setup.status()
 
     @classmethod

bot_bottle/backend/firecracker/setup.py

@@ -13,6 +13,7 @@ generic `./cli.py backend {setup,status}` command dispatches to.
 
 from __future__ import annotations
 
+import fcntl
 import os
 import shutil
 import subprocess
@@ -22,6 +23,9 @@ from pathlib import Path
 from . import netpool
 from . import util
 
+# KVM_GET_API_VERSION = _IO(KVMIO=0xAE, 0x00): cheapest proof of KVM access.
+_KVM_GET_API_VERSION = 0xAE00
+
 
 _FC_RELEASES = "https://github.com/firecracker-microvm/firecracker/releases"
 _UNIT_PATH = Path("/etc/systemd/system") / netpool.SYSTEMD_UNIT
@@ -219,14 +223,64 @@ def teardown() -> int:
     return 0
 
 
+def _firecracker_binary_ok() -> bool:
+    """True iff the firecracker binary is on PATH and `--version` exits 0."""
+    if shutil.which("firecracker") is None:
+        return False
+    try:
+        return subprocess.run(
+            ["firecracker", "--version"],
+            capture_output=True, check=False, timeout=5,
+        ).returncode == 0
+    except (OSError, subprocess.TimeoutExpired):
+        return False
+
+
+def _kvm_accessible() -> bool:
+    """True iff /dev/kvm can be opened and responds to KVM_GET_API_VERSION.
+
+    Uses an ioctl rather than os.access() so that a device with correct
+    permission bits but a non-functional KVM subsystem is caught here
+    rather than at VM boot time."""
+    if not os.path.exists(util._KVM_DEVICE):
+        return False
+    try:
+        with open(util._KVM_DEVICE, "rb") as kvm:
+            fcntl.ioctl(kvm, _KVM_GET_API_VERSION)
+        return True
+    except OSError:
+        return False
+
+
 def status() -> int:
-    # Readiness == what the launch preflight hard-requires: the TAP pool
+    # Readiness == what the launch preflight hard-requires: the binary
-    # present (unprivileged, authoritative) and no range overlap. Listing
+    # executable, /dev/kvm accessible, the TAP pool present, and no range
-    # the nft table usually needs root, so — like the preflight — an
+    # overlap. Listing the nft table usually needs root, so — like the
-    # unconfirmable table is reported but NOT treated as not-ready; the
+    # preflight — an unconfirmable table is reported but NOT treated as
-    # post-boot isolation probe is the authoritative check. This keeps an
+    # not-ready; the post-boot isolation probe is the authoritative check.
-    # unprivileged `backend status` usable as a launch gate.
+    # This keeps an unprivileged `backend status` usable as a launch gate.
     ok = True
+    if _firecracker_binary_ok():
+        sys.stderr.write(f"firecracker binary: ok ({shutil.which('firecracker')})\n")
+    else:
+        fc_path = shutil.which("firecracker")
+        if fc_path is None:
+            sys.stderr.write("firecracker binary: NOT found on PATH\n")
+        else:
+            sys.stderr.write(
+                f"firecracker binary: found ({fc_path}) but `--version` failed\n"
+            )
+        ok = False
+    if _kvm_accessible():
+        sys.stderr.write(f"KVM: {util._KVM_DEVICE} accessible\n")
+    else:
+        if not os.path.exists(util._KVM_DEVICE):
+            sys.stderr.write(f"KVM: {util._KVM_DEVICE} not present\n")
+        else:
+            sys.stderr.write(
+                f"KVM: {util._KVM_DEVICE} not accessible (open/ioctl failed)\n"
+            )
+        ok = False
     missing = netpool.missing_taps()
     total = netpool.pool_size()
     if missing:

bot_bottle/backend/macos_container/backend.py

@@ -2,7 +2,8 @@
 
 from __future__ import annotations
 
-from contextlib import contextmanager
+import io
+from contextlib import contextmanager, redirect_stderr
 from pathlib import Path
 from typing import Generator, Sequence
 
@@ -43,8 +44,11 @@ class MacosContainerBottleBackend(
         return _setup.setup()
 
     @classmethod
-    def status(cls) -> int:
+    def status(cls, *, quiet: bool = False) -> int:
         from . import setup as _setup
+        if quiet:
+            with redirect_stderr(io.StringIO()):
+                return _setup.status()
         return _setup.status()
 
     @classmethod

docs/ci.md

@@ -1,13 +1,23 @@
 # CI
 
 The test workflow lives at [`.gitea/workflows/test.yml`](../.gitea/workflows/test.yml).
-It runs `tests/run_tests.py` (full suite — unit + integration) on:
+It runs the unit suite plus one integration job per backend
+(`integration-docker`, `integration-firecracker`) on:
 
 - every push to a branch with an open pull request, and
 - every push to `main`.
 
-Integration tests need Docker on the runner; they skip cleanly via
+Each integration job selects its backend via `BOT_BOTTLE_BACKEND` and
-`tests/_docker.skip_unless_docker` when no daemon is reachable.
+runs a **preflight** (`./cli.py backend status --backend=<name>`) that
+prints a clear per-check readiness summary and fails the job when the
+backend is missing — so absent infrastructure is visible at the job level
+rather than hidden among per-test `unittest.skip` lines. The skip guards in
+[`tests/_backend.py`](../tests/_backend.py) gate on the same readiness
+check (`bot_bottle.backend.has_backend`): backend-agnostic tests use
+`skip_unless_selected_backend_available()` and run through whichever
+backend is selected (checking, e.g., Linux + `/dev/kvm` for Firecracker
+rather than unrelated Docker availability); Docker-implementation tests use
+`skip_unless_backend("docker")` and no-op under a non-Docker run.
 
 A small subset of integration tests skip when running specifically
 under Gitea Actions (`GITEA_ACTIONS=true`), because `act_runner` runs

tests/README.md

@@ -2,14 +2,15 @@
 
 Plain-Python test suite using stdlib `unittest`. No external
 dependencies. Unit tests run anywhere Python 3 is present; integration
-tests need Docker and skip cleanly otherwise.
+tests run through the backend named by `BOT_BOTTLE_BACKEND` (default
+`docker`) and skip cleanly when that backend isn't available on the host.
 
 ## Layout
 
 ```
 tests/
   fixtures.py                       # JSON manifest builders (shared)
-  _docker.py                        # docker-availability skip helper (shared)
+  _backend.py                       # backend selection + skip guards (shared)
   unit/
     test_egress.py
     test_egress_addon_core.py
@@ -73,7 +74,7 @@ BOT_BOTTLE_RUN_CANARIES=1 python -m unittest discover -t . -s tests/canaries -v
 ## Adding a test
 
 1. Pick the directory: `tests/unit/` for a pure unit test,
-   `tests/integration/` for one that needs Docker.
+   `tests/integration/` for one that needs a backend.
 2. Filename: `test_<topic>.py`.
 3. Boilerplate:
    ```python
@@ -88,5 +89,19 @@ BOT_BOTTLE_RUN_CANARIES=1 python -m unittest discover -t . -s tests/canaries -v
    if __name__ == "__main__":
        unittest.main()
    ```
-4. For Docker-dependent tests, decorate the class with
+4. Skip guards live in `tests._backend` and gate on the backend's own
-   `@skip_unless_docker()` from `tests._docker`.
+   readiness check, `bot_bottle.backend.has_backend` — the same probe
+   behind `./cli.py backend status`:
+   - Backend-agnostic tests (go through `get_bottle_backend()`) decorate
+     the class with `@skip_unless_selected_backend_available()` — the test
+     runs against whichever backend `BOT_BOTTLE_BACKEND` selects and skips
+     unless that backend is available (checking, e.g., Linux + `/dev/kvm`
+     for Firecracker rather than unrelated Docker availability).
+   - Backend-specific tests (exercise `DockerBroker`, `DockerGateway`,
+     `backend.docker.*`, …) decorate with `@skip_unless_backend("docker")`
+     so they no-op under a run targeting a different backend.
+
+   Each CI integration job runs `./cli.py backend status --backend=<name>`
+   as a preflight, which prints a clear per-check summary and exits non-zero
+   when the backend is missing — so absent infrastructure fails the job
+   instead of hiding among per-test `unittest.skip` lines.

tests/_backend.py

@@ -0,0 +1,71 @@
+"""Backend selection + readiness-aware skip guards for the integration suite.
+
+Each integration test targets the backend named by ``BOT_BOTTLE_BACKEND``
+(default ``docker``) and gates on that backend's full readiness check —
+``is_backend_ready()`` (equivalent to ``./cli.py backend status``), not just
+a binary-on-PATH probe. When the backend is not ready, diagnostic output is
+printed during test discovery so the operator sees a concrete reason for each
+skip.
+"""
+
+from __future__ import annotations
+
+import os
+import unittest
+
+from bot_bottle.backend import is_backend_ready
+
+# Default when ``BOT_BOTTLE_BACKEND`` is unset. Docker preserves the historical
+# Docker-backed CI path (and mirrors the pin in ``test_sandbox_escape``).
+DEFAULT_BACKEND = "docker"
+
+
+def selected_backend() -> str:
+    """The backend this test run targets, from ``BOT_BOTTLE_BACKEND``.
+
+    Mirrors the CLI's env selector; unset means ``docker`` so an
+    unconfigured run behaves exactly as the suite did before backends were
+    pluggable.
+    """
+    return os.environ.get("BOT_BOTTLE_BACKEND") or DEFAULT_BACKEND
+
+
+def skip_unless_backend(backend: str):
+    """Skip a backend-specific test unless the selected backend matches AND
+    that backend is fully ready.
+
+    Docker-implementation tests (``DockerBroker``, ``DockerGateway``,
+    ``backend.docker.*``) use ``skip_unless_backend("docker")`` so they no-op
+    under a run targeting a different backend instead of testing Docker
+    internals that run doesn't exercise — the guard reads
+    ``BOT_BOTTLE_BACKEND`` rather than "is Docker installed".
+
+    When the backend is not ready, ``status()`` output is printed so the
+    operator sees a concrete diagnostic for each skipped test module.
+    """
+    sel = selected_backend()
+    if sel != backend:
+        return unittest.skip(
+            f"backend {backend!r} not selected (BOT_BOTTLE_BACKEND={sel})"
+        )
+    return unittest.skipUnless(
+        is_backend_ready(backend, quiet=False),
+        f"{backend} backend not ready",
+    )
+
+
+def skip_unless_selected_backend_available():
+    """Skip a backend-agnostic test unless the *selected* backend is fully ready.
+
+    The test then runs through whichever backend ``BOT_BOTTLE_BACKEND`` names,
+    gated on that backend's full status() check (e.g. daemon reachable, TAP
+    pool present for Firecracker) rather than just a binary-on-PATH probe.
+
+    When the backend is not ready, ``status()`` output is printed so the
+    operator sees a concrete diagnostic for each skipped test module.
+    """
+    backend = selected_backend()
+    return unittest.skipUnless(
+        is_backend_ready(backend, quiet=False),
+        f"selected backend {backend!r} not ready",
+    )

tests/_docker.py

@@ -1,45 +0,0 @@
-"""Docker availability check used by integration tests."""
-
-from __future__ import annotations
-
-import os
-import shutil
-import subprocess
-import unittest
-
-
-def docker_available() -> bool:
-    if os.environ.get("SKIP_DOCKER_TESTS"):
-        return False
-    if shutil.which("docker") is None:
-        return False
-    try:
-        return (
-            subprocess.run(
-                ["docker", "info"],
-                stdout=subprocess.DEVNULL,
-                stderr=subprocess.DEVNULL,
-                check=False,
-                timeout=5,
-            ).returncode
-            == 0
-        )
-    except subprocess.TimeoutExpired:
-        return False
-
-
-def skip_unless_docker(reason: str = "docker unreachable"):
-    return unittest.skipUnless(docker_available(), reason)
-
-
-def skip_unless_docker_or_firecracker(
-    reason: str = "neither Docker nor Firecracker selected",
-):
-    """Skip a backend-agnostic test unless one supported backend can run.
-
-    Firecracker does not require the host Docker daemon. The KVM coverage job
-    deliberately sets ``SKIP_DOCKER_TESTS`` to exclude Docker-only integration
-    classes while still exercising this path.
-    """
-    firecracker_selected = os.environ.get("BOT_BOTTLE_BACKEND") == "firecracker"
-    return unittest.skipUnless(firecracker_selected or docker_available(), reason)

tests/integration/test_gateway_image.py

@@ -25,14 +25,14 @@ import os
 import subprocess
 import unittest
 
-from tests._docker import skip_unless_docker
+from tests._backend import skip_unless_backend
 
 
 _IMAGE = "bot-bottle-gateway-test:chunk1"
 _DOCKERFILE = "Dockerfile.gateway"
 
 
-@skip_unless_docker()
+@skip_unless_backend("docker")
 @unittest.skipIf(
     os.environ.get("GITEA_ACTIONS") == "true",
     "skipped under act_runner: multi-stage build pulls a 200+MB "

tests/integration/test_multitenant_isolation.py

@@ -31,7 +31,7 @@ from bot_bottle.backend.docker.gateway_net import next_free_ip
 from bot_bottle.orchestrator.client import OrchestratorClient
 from bot_bottle.orchestrator.gateway import GATEWAY_IMAGE, GATEWAY_NAME, GATEWAY_NETWORK
 from bot_bottle.orchestrator.lifecycle import OrchestratorService
-from tests._docker import skip_unless_docker
+from tests._backend import skip_unless_backend
 
 # One upstream reachable under two names; reflects the Authorization header so
 # the probe can see exactly what the gateway injected (or didn't).
@@ -72,7 +72,7 @@ _PROBE_SRC = (
 )
 
 
-@skip_unless_docker()
+@skip_unless_backend("docker")
 @unittest.skipIf(
     os.environ.get("GITEA_ACTIONS") == "true",
     "skipped under act_runner: the orchestrator container bind-mounts the repo "

tests/integration/test_orchestrator_docker_broker.py

@@ -13,12 +13,12 @@ import unittest
 
 from bot_bottle.orchestrator.broker import LaunchRequest, sign_request
 from bot_bottle.orchestrator.docker_broker import DockerBroker, container_name
-from tests._docker import skip_unless_docker
+from tests._backend import skip_unless_backend
 
 IMAGE = "busybox"
 
 
-@skip_unless_docker()
+@skip_unless_backend("docker")
 class TestDockerBrokerIntegration(unittest.TestCase):
     def setUp(self) -> None:
         self.secret = secrets.token_bytes(16)

tests/integration/test_orchestrator_docker_control_plane_auth.py

@@ -28,7 +28,7 @@ from pathlib import Path
 from bot_bottle.orchestrator.client import OrchestratorClient
 from bot_bottle.orchestrator.lifecycle import OrchestratorService
 from bot_bottle.paths import host_control_plane_token
-from tests._docker import skip_unless_docker
+from tests._backend import skip_unless_backend
 
 # Fixed (not per-run-suffixed) so repeated runs reuse the same layer-cached
 # image instead of leaking a new dangling tag on every invocation.
@@ -37,7 +37,7 @@ _TEST_GATEWAY_IMAGE = "bot-bottle-gateway:itest"
 _TEST_INFRA_IMAGE = "bot-bottle-infra:itest"
 
 
-@skip_unless_docker()
+@skip_unless_backend("docker")
 @unittest.skipIf(
     os.environ.get("GITEA_ACTIONS") == "true",
     "skipped under act_runner: the orchestrator container bind-mounts the repo "

tests/integration/test_orchestrator_docker_gateway.py

@@ -11,12 +11,12 @@ import subprocess
 import unittest
 
 from bot_bottle.orchestrator.gateway import DockerGateway
-from tests._docker import skip_unless_docker
+from tests._backend import skip_unless_backend
 
 IMAGE = "busybox"
 
 
-@skip_unless_docker()
+@skip_unless_backend("docker")
 class TestDockerGatewayIntegration(unittest.TestCase):
     def setUp(self) -> None:
         self.name = "bot-bottle-orch-gateway-itest-" + secrets.token_hex(4)

tests/integration/test_orchestrator_docker_gateway_build.py

@@ -12,12 +12,12 @@ import subprocess
 import unittest
 
 from bot_bottle.orchestrator.gateway import DockerGateway
-from tests._docker import skip_unless_docker
+from tests._backend import skip_unless_backend
 
 IMAGE = "busybox"
 
 
-@skip_unless_docker()
+@skip_unless_backend("docker")
 class TestDockerGatewayImageExists(unittest.TestCase):
     def test_image_exists_true_for_present_false_for_absent(self) -> None:
         # Ensure the tiny image is present (build_if_missing is disabled here

tests/integration/test_orphan_cleanup.py

@@ -18,10 +18,10 @@ from bot_bottle.backend.docker.network import (
     network_create_internal,
     network_remove,
 )
-from tests._docker import skip_unless_docker
+from tests._backend import skip_unless_backend
 
 
-@skip_unless_docker()
+@skip_unless_backend("docker")
 class TestOrphanCleanup(unittest.TestCase):
     def setUp(self):
         self.slug = f"cb-test-orphan-{os.getpid()}"

tests/integration/test_sandbox_escape.py

@@ -31,7 +31,7 @@ from pathlib import Path
 from bot_bottle.backend import BottleSpec, get_bottle_backend
 from bot_bottle.bottle_state import cleanup_state
 from bot_bottle.manifest import ManifestIndex
-from tests._docker import skip_unless_docker_or_firecracker
+from tests._backend import skip_unless_selected_backend_available
 
 
 # Secrets planted in the bottle env as literals (agents substitute via
@@ -67,7 +67,7 @@ _DUMMY_HOST_KEY = (
 )
 
 
-@skip_unless_docker_or_firecracker()
+@skip_unless_selected_backend_available()
 @unittest.skipIf(
     os.environ.get("GITEA_ACTIONS") == "true"
     and os.environ.get("BOT_BOTTLE_BACKEND") != "firecracker",

tests/unit/test_backend_selection.py

@@ -385,6 +385,60 @@ class TestHasBackend(unittest.TestCase):
         self.assertFalse(has_backend("nonexistent"))
 
 
+class TestIsBackendAvailable(unittest.TestCase):
+    def test_delegates_to_has_backend(self):
+        from bot_bottle.backend import is_backend_available
+        with patch.object(backend_mod, "_backends", {}):
+            self.assertFalse(is_backend_available("docker"))
+
+    def test_known_and_available(self):
+        class _Ready:
+            def is_available(self):
+                return True
+
+        from bot_bottle.backend import is_backend_available
+        with patch.object(backend_mod, "_backends", {"docker": _Ready()}):
+            self.assertTrue(is_backend_available("docker"))
+
+
+class TestIsBackendReady(unittest.TestCase):
+    def test_unknown_backend_returns_false(self):
+        from bot_bottle.backend import is_backend_ready
+        with patch.object(backend_mod, "_backends", {}):
+            self.assertFalse(is_backend_ready("docker"))
+
+    def test_ready_when_status_returns_zero(self):
+        class _ReadyBackend:
+            def status(self, *, quiet: bool = False) -> int:
+                return 0
+
+        from bot_bottle.backend import is_backend_ready
+        with patch.object(backend_mod, "_backends", {"docker": _ReadyBackend()}):
+            self.assertTrue(is_backend_ready("docker"))
+
+    def test_not_ready_when_status_nonzero(self):
+        class _BrokenBackend:
+            def status(self, *, quiet: bool = False) -> int:
+                return 1
+
+        from bot_bottle.backend import is_backend_ready
+        with patch.object(backend_mod, "_backends", {"docker": _BrokenBackend()}):
+            self.assertFalse(is_backend_ready("docker"))
+
+    def test_quiet_flag_forwarded(self):
+        calls = []
+
+        class _SpyBackend:
+            def status(self, *, quiet: bool = False) -> int:
+                calls.append(quiet)
+                return 0
+
+        from bot_bottle.backend import is_backend_ready
+        with patch.object(backend_mod, "_backends", {"docker": _SpyBackend()}):
+            is_backend_ready("docker", quiet=True)
+        self.assertEqual([True], calls)
+
+
 class TestEnsureOrchestrator(unittest.TestCase):
     """The backend-agnostic orchestrator bring-up entry point. Docker starts
     the orchestrator + gateway containers; firecracker boots the infra VM;

tests/unit/test_backend_setup.py

@@ -328,5 +328,143 @@ class TestNetpoolShellRenderers(unittest.TestCase):
         self.assertIn("BOT_BOTTLE_FC_POOL_SIZE=4", out)
 
 
+class TestFirecrackerBinaryCheck(unittest.TestCase):
+    def test_binary_missing_returns_false(self):
+        with patch.object(fc.shutil, "which", return_value=None):
+            self.assertFalse(fc._firecracker_binary_ok())
+
+    def test_binary_present_and_runs_ok(self):
+        with patch.object(fc.shutil, "which", return_value="/usr/bin/firecracker"), \
+             patch.object(fc.subprocess, "run",
+                          return_value=subprocess.CompletedProcess([], 0)):
+            self.assertTrue(fc._firecracker_binary_ok())
+
+    def test_binary_found_but_exits_nonzero(self):
+        with patch.object(fc.shutil, "which", return_value="/usr/bin/firecracker"), \
+             patch.object(fc.subprocess, "run",
+                          return_value=subprocess.CompletedProcess([], 1)):
+            self.assertFalse(fc._firecracker_binary_ok())
+
+    def test_binary_found_but_oserror(self):
+        with patch.object(fc.shutil, "which", return_value="/usr/bin/firecracker"), \
+             patch.object(fc.subprocess, "run", side_effect=OSError("exec failed")):
+            self.assertFalse(fc._firecracker_binary_ok())
+
+
+class TestFirecrackerKvmCheck(unittest.TestCase):
+    def test_kvm_device_absent_returns_false(self):
+        with patch.object(fc.os.path, "exists", return_value=False):
+            self.assertFalse(fc._kvm_accessible())
+
+    def test_kvm_accessible_when_ioctl_succeeds(self):
+        m = MagicMock()
+        m.__enter__ = MagicMock(return_value=m)
+        m.__exit__ = MagicMock(return_value=False)
+        with patch.object(fc.os.path, "exists", return_value=True), \
+             patch("builtins.open", return_value=m), \
+             patch.object(fc.fcntl, "ioctl", return_value=12):
+            self.assertTrue(fc._kvm_accessible())
+
+    def test_kvm_present_but_ioctl_fails(self):
+        m = MagicMock()
+        m.__enter__ = MagicMock(return_value=m)
+        m.__exit__ = MagicMock(return_value=False)
+        with patch.object(fc.os.path, "exists", return_value=True), \
+             patch("builtins.open", return_value=m), \
+             patch.object(fc.fcntl, "ioctl", side_effect=OSError("permission denied")):
+            self.assertFalse(fc._kvm_accessible())
+
+
+class TestFirecrackerStatusRuntime(unittest.TestCase):
+    """status() reports binary and KVM problems and returns non-zero."""
+
+    def _apply_pool_ok(self, stack: contextlib.ExitStack) -> None:
+        stack.enter_context(patch.object(netpool, "missing_taps", return_value=[]))
+        stack.enter_context(patch.object(netpool, "pool_size", return_value=8))
+        stack.enter_context(patch.object(netpool, "overlapping_routes", return_value=[]))
+        stack.enter_context(patch.object(fc, "_report_persistence", lambda: None))
+
+    def test_status_fails_when_binary_missing(self):
+        with contextlib.ExitStack() as stack:
+            stack.enter_context(
+                patch.object(fc, "_firecracker_binary_ok", return_value=False))
+            stack.enter_context(
+                patch.object(fc, "_kvm_accessible", return_value=True))
+            stack.enter_context(
+                patch.object(fc.shutil, "which", return_value=None))
+            self._apply_pool_ok(stack)
+            rc, out = _cap(fc.status)
+        self.assertEqual(1, rc)
+        self.assertIn("NOT found on PATH", out)
+
+    def test_status_fails_when_kvm_not_accessible(self):
+        with contextlib.ExitStack() as stack:
+            stack.enter_context(
+                patch.object(fc, "_firecracker_binary_ok", return_value=True))
+            stack.enter_context(
+                patch.object(fc.shutil, "which", return_value="/usr/bin/firecracker"))
+            stack.enter_context(
+                patch.object(fc, "_kvm_accessible", return_value=False))
+            stack.enter_context(
+                patch.object(fc.os.path, "exists", return_value=True))
+            self._apply_pool_ok(stack)
+            rc, out = _cap(fc.status)
+        self.assertEqual(1, rc)
+        self.assertIn("not accessible", out)
+
+    def test_status_ok_when_binary_and_kvm_ready(self):
+        with contextlib.ExitStack() as stack:
+            stack.enter_context(
+                patch.object(fc, "_firecracker_binary_ok", return_value=True))
+            stack.enter_context(
+                patch.object(fc.shutil, "which", return_value="/usr/bin/firecracker"))
+            stack.enter_context(
+                patch.object(fc, "_kvm_accessible", return_value=True))
+            stack.enter_context(
+                patch.object(netpool, "nft_table_present", return_value=True))
+            self._apply_pool_ok(stack)
+            rc, out = _cap(fc.status)
+        self.assertEqual(0, rc)
+        self.assertIn("firecracker binary: ok", out)
+        self.assertIn("KVM:", out)
+
+
+class TestBackendStatusQuiet(unittest.TestCase):
+    """status(quiet=True) routes the underlying status() call through
+    redirect_stderr so diagnostic output is suppressed. Verify the return
+    code is propagated and that calling with quiet=False leaves the non-quiet
+    path active (covered by the other TestDockerSetupStatus tests)."""
+
+    def test_docker_quiet_true_propagates_return_code(self):
+        from bot_bottle.backend.docker.backend import DockerBottleBackend
+        with patch.object(dk, "status", return_value=0):
+            self.assertEqual(0, DockerBottleBackend.status(quiet=True))
+
+    def test_docker_quiet_true_suppresses_stderr(self):
+        import io as _io
+        from bot_bottle.backend.docker.backend import DockerBottleBackend
+
+        def _loud_status():
+            import sys
+            print("should be suppressed", file=sys.stderr)
+            return 0
+
+        with patch.object(dk, "status", side_effect=_loud_status):
+            buf = _io.StringIO()
+            with contextlib.redirect_stderr(buf):
+                DockerBottleBackend.status(quiet=True)
+        self.assertEqual("", buf.getvalue())
+
+    def test_firecracker_quiet_true_propagates_return_code(self):
+        from bot_bottle.backend.firecracker.backend import FirecrackerBottleBackend
+        with patch.object(fc, "status", return_value=1):
+            self.assertEqual(1, FirecrackerBottleBackend.status(quiet=True))
+
+    def test_macos_quiet_true_propagates_return_code(self):
+        from bot_bottle.backend.macos_container.backend import MacosContainerBottleBackend
+        with patch.object(mc, "status", return_value=0):
+            self.assertEqual(0, MacosContainerBottleBackend.status(quiet=True))
+
+
 if __name__ == "__main__":
     unittest.main()

tests/unit/test_backend_skip_guards.py

@@ -0,0 +1,78 @@
+"""Tests for the backend-aware skip guards in ``tests/_backend.py``.
+
+The guards delegate their readiness check to
+``bot_bottle.backend.is_backend_ready`` (the probe behind ``./cli.py backend
+status``); here that probe is mocked so the unit job asserts the
+selection/skip logic without either backend present on the runner.
+"""
+
+from __future__ import annotations
+
+import os
+import unittest
+from unittest.mock import patch
+
+from tests._backend import (
+    selected_backend,
+    skip_unless_backend,
+    skip_unless_selected_backend_available,
+)
+
+
+def _skipped(decorated: type) -> bool:
+    return getattr(decorated, "__unittest_skip__", False)
+
+
+def _new_case() -> type:
+    return type("Case", (unittest.TestCase,), {})
+
+
+class TestSelectedBackend(unittest.TestCase):
+    def test_defaults_to_docker_when_unset(self):
+        with patch.dict(os.environ, {}, clear=True):
+            self.assertEqual("docker", selected_backend())
+
+    def test_reads_env(self):
+        with patch.dict(os.environ, {"BOT_BOTTLE_BACKEND": "firecracker"}, clear=True):
+            self.assertEqual("firecracker", selected_backend())
+
+
+class TestSkipUnlessBackend(unittest.TestCase):
+    def test_skips_when_other_backend_selected(self):
+        # A different backend is selected — no host probe needed, skip.
+        with patch.dict(os.environ, {"BOT_BOTTLE_BACKEND": "firecracker"}, clear=True), \
+                patch("tests._backend.is_backend_ready") as has:
+            decorated = skip_unless_backend("docker")(_new_case())
+        self.assertTrue(_skipped(decorated))
+        has.assert_not_called()
+
+    def test_runs_when_selected_and_available(self):
+        with patch.dict(os.environ, {"BOT_BOTTLE_BACKEND": "docker"}, clear=True), \
+                patch("tests._backend.is_backend_ready", return_value=True):
+            decorated = skip_unless_backend("docker")(_new_case())
+        self.assertFalse(_skipped(decorated))
+
+    def test_skips_when_selected_but_unavailable(self):
+        with patch.dict(os.environ, {"BOT_BOTTLE_BACKEND": "docker"}, clear=True), \
+                patch("tests._backend.is_backend_ready", return_value=False):
+            decorated = skip_unless_backend("docker")(_new_case())
+        self.assertTrue(_skipped(decorated))
+
+
+class TestSkipUnlessSelectedBackendAvailable(unittest.TestCase):
+    def test_runs_when_selected_backend_available(self):
+        with patch.dict(os.environ, {"BOT_BOTTLE_BACKEND": "firecracker"}, clear=True), \
+                patch("tests._backend.is_backend_ready", return_value=True) as has:
+            decorated = skip_unless_selected_backend_available()(_new_case())
+        self.assertFalse(_skipped(decorated))
+        has.assert_called_once_with("firecracker", quiet=False)
+
+    def test_skips_when_selected_backend_unavailable(self):
+        with patch.dict(os.environ, {"BOT_BOTTLE_BACKEND": "firecracker"}, clear=True), \
+                patch("tests._backend.is_backend_ready", return_value=False):
+            decorated = skip_unless_selected_backend_available()(_new_case())
+        self.assertTrue(_skipped(decorated))
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/unit/test_docker_test_helpers.py

@@ -1,35 +0,0 @@
-"""Tests for integration-test backend selection helpers."""
-
-from __future__ import annotations
-
-import os
-import unittest
-from unittest.mock import patch
-
-from tests._docker import skip_unless_docker_or_firecracker
-
-
-class TestSkipUnlessDockerOrFirecracker(unittest.TestCase):
-    def test_firecracker_runs_when_docker_tests_are_disabled(self):
-        with patch.dict(
-            os.environ,
-            {"BOT_BOTTLE_BACKEND": "firecracker", "SKIP_DOCKER_TESTS": "1"},
-            clear=True,
-        ):
-            decorated = skip_unless_docker_or_firecracker()(type("Case", (), {}))
-
-        self.assertFalse(getattr(decorated, "__unittest_skip__", False))
-
-    def test_non_firecracker_still_skips_when_docker_tests_are_disabled(self):
-        with patch.dict(
-            os.environ,
-            {"BOT_BOTTLE_BACKEND": "docker", "SKIP_DOCKER_TESTS": "1"},
-            clear=True,
-        ):
-            decorated = skip_unless_docker_or_firecracker()(type("Case", (), {}))
-
-        self.assertTrue(getattr(decorated, "__unittest_skip__", False))
-
-
-if __name__ == "__main__":
-    unittest.main()

tests/unit/test_firecracker_backend.py

@@ -136,7 +136,9 @@ class TestFirecrackerStatus(unittest.TestCase):
         from bot_bottle.backend.firecracker import setup as fc_setup
         with patch.object(fc_setup.netpool, "missing_taps", return_value=[]), \
              patch.object(fc_setup.netpool, "overlapping_routes", return_value=[]), \
-             patch.object(fc_setup.shutil, "which", return_value=None):
+             patch.object(fc_setup.shutil, "which", return_value=None), \
+             patch.object(fc_setup, "_firecracker_binary_ok", return_value=True), \
+             patch.object(fc_setup, "_kvm_accessible", return_value=True):
             rc, out = self._run()
         self.assertEqual(0, rc)
         self.assertIn("unverified", out)