feat(gui): garde-fou runtime — désactive un moteur optionnel non embarqué

Condition du GO-CONDITIONNEL Qwen sur le lot engine capabilities
(cb3b767/890edb3/5e5f0bd) : un profil YAML forçant enable_eds/enable_gliner
ne doit pas déclencher un chargement voué à l'échec silencieux.

NerManagers.ensure_loaded() applique désormais un garde-fou via la sonde
engine_capabilities.capabilities_map() (injectable) AVANT toute tentative
de load EDS/GLiNER : si le moteur optionnel demandé est indisponible dans
le build courant → warning + désactivation forcée dans les réglages runtime.
Best-effort (sonde en échec ⇒ réglages inchangés, les try/except de load
protègent déjà). Sonde légère (find_spec), aucun import lourd.

CamemBERT (requis) inchangé. Diff limité au garde-fou + tests cibles.

TDD : 4 tests (test_gui_v6_engine_bridge.py) — eds/gliner indispo désactivés
et jamais chargés, moteur dispo conservé, fail-safe sonde. 282 unit passed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/unit/test_gui_v6_engine_bridge.py

@@ -126,6 +126,89 @@ def test_optional_manager_failure_is_tolerated():
     assert managers.use_hf is True
 
 
+# -- garde-fou capabilities runtime ----------------------------------------
+
+
+class _FakeCap:
+    """Capability minimale pour injecter une sonde dans les tests."""
+
+    def __init__(self, available, reason="(test)"):
+        self.available = available
+        self.reason = reason
+
+
+def _caps_provider(eds_ok, gliner_ok):
+    def provider():
+        return {
+            "camembert": _FakeCap(True),
+            "eds": _FakeCap(eds_ok),
+            "gliner": _FakeCap(gliner_ok),
+        }
+
+    return provider
+
+
+def test_guard_disables_unavailable_eds_before_load():
+    # Profil/config forçant EDS alors que le moteur n'est pas embarqué.
+    settings = EngineSettings(enable_eds=True)
+    counter = {"camembert": 0, "eds": 0, "gliner": 0}
+    managers = NerManagers(
+        settings,
+        factories=_counting_factories(counter),
+        caps_provider=_caps_provider(eds_ok=False, gliner_ok=True),
+    )
+    assert managers.ensure_loaded() == ManagerState.READY
+    assert settings.enable_eds is False  # désactivation forcée
+    assert counter["eds"] == 0  # jamais tenté de charger
+    assert managers.as_kwargs()["ner_manager"] is None
+
+
+def test_guard_disables_unavailable_gliner_before_load():
+    settings = EngineSettings(enable_gliner=True)
+    counter = {"camembert": 0, "eds": 0, "gliner": 0}
+    managers = NerManagers(
+        settings,
+        factories=_counting_factories(counter),
+        caps_provider=_caps_provider(eds_ok=True, gliner_ok=False),
+    )
+    assert managers.ensure_loaded() == ManagerState.READY
+    assert settings.enable_gliner is False
+    assert counter["gliner"] == 0
+    assert managers.as_kwargs()["gliner_manager"] is None
+
+
+def test_guard_keeps_available_engine_enabled():
+    settings = EngineSettings(enable_eds=True, enable_gliner=True)
+    counter = {"camembert": 0, "eds": 0, "gliner": 0}
+    managers = NerManagers(
+        settings,
+        factories=_counting_factories(counter),
+        caps_provider=_caps_provider(eds_ok=True, gliner_ok=True),
+    )
+    assert managers.ensure_loaded() == ManagerState.READY
+    assert settings.enable_eds is True
+    assert settings.enable_gliner is True
+    assert counter["eds"] == 1
+    assert counter["gliner"] == 1
+
+
+def test_guard_failsafe_when_probe_raises():
+    settings = EngineSettings(enable_eds=True)
+    counter = {"camembert": 0, "eds": 0, "gliner": 0}
+
+    def boom():
+        raise RuntimeError("probe ko")
+
+    managers = NerManagers(
+        settings, factories=_counting_factories(counter), caps_provider=boom
+    )
+    # Best-effort : une sonde en échec ne bloque pas le chargement et ne
+    # modifie pas les réglages (les try/except de load protègent déjà).
+    assert managers.ensure_loaded() == ManagerState.READY
+    assert settings.enable_eds is True
+    assert counter["eds"] == 1
+
+
 # -- make_process_fn -------------------------------------------------------
 
 def test_process_fn_calls_engine_with_kwargs(tmp_path):