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+# tests/gui/camera_config/test_trigger_config_dialog.py
+from __future__ import annotations
+
+import pytest
+
+from dlclivegui.config import CameraSettings
+from dlclivegui.gui.camera_config.trigger_config_dialog import (
+    TriggerConfigDialog,
+    _backend_namespace,
+    trigger_ui_profile_for_backend,
+)
+
+
+class TestTriggerUiProfiles:
+    @pytest.mark.parametrize(
+        ("backend", "supports_input", "supports_master", "show_strobe", "show_line"),
+        [
+            ("gentl", True, True, True, True),
+            ("basler", True, True, False, True),
+            ("opencv", False, False, False, False),
+            ("fake", False, False, False, False),
+        ],
+    )
+    def test_profile_capabilities_by_backend(
+        self,
+        backend: str,
+        supports_input: bool,
+        supports_master: bool,
+        show_strobe: bool,
+        show_line: bool,
+    ):
+        profile = trigger_ui_profile_for_backend(backend)
+
+        assert profile.supports_input is supports_input
+        assert profile.supports_master is supports_master
+        assert profile.show_strobe_fields is show_strobe
+        assert profile.show_line_output_fields is show_line
+
+    def test_profile_backend_is_case_insensitive(self):
+        upper = trigger_ui_profile_for_backend("GeNtL")
+        lower = trigger_ui_profile_for_backend("gentl")
+
+        assert upper == lower
+
+
+class TestBackendNamespace:
+    def test_backend_namespace_creates_backend_dict(self):
+        cam = CameraSettings(backend="gentl", index=0, properties={})
+
+        ns = _backend_namespace(cam)
+
+        assert ns == {}
+        assert cam.properties == {"gentl": {}}
+
+    def test_backend_namespace_replaces_non_dict_properties(self):
+        cam = CameraSettings(backend="gentl", index=0, properties={})
+        cam.properties = None
+
+        ns = _backend_namespace(cam)
+        ns["trigger"] = {"role": "external"}
+
+        assert cam.properties == {"gentl": {"trigger": {"role": "external"}}}
+
+    def test_backend_namespace_replaces_non_dict_namespace(self):
+        cam = CameraSettings(backend="gentl", index=0, properties={"gentl": "bad"})
+
+        ns = _backend_namespace(cam)
+
+        assert ns == {}
+        assert cam.properties == {"gentl": {}}
+
+
+class TestTriggerConfigDialogPresentation:
+    @pytest.mark.gui
+    def test_unknown_backend_exposes_only_off_role_and_disables_trigger_fields(self, qtbot):
+        cam = CameraSettings(backend="opencv", index=0, properties={})
+        dlg = TriggerConfigDialog(cam)
+        qtbot.addWidget(dlg)
+
+        roles = [dlg.role_combo.itemData(i) for i in range(dlg.role_combo.count())]
+
+        assert roles == ["off"]
+        assert not dlg.selector_edit.isVisible()
+        assert not dlg.source_combo.isVisible()
+        assert not dlg.activation_combo.isVisible()
+        assert not dlg.output_line_edit.isVisible()
+        assert not dlg.strobe_polarity_combo.isVisible()
+
+    @pytest.mark.gui
+    def test_gentl_profile_shows_input_master_line_and_strobe_fields(self, qtbot):
+        cam = CameraSettings(backend="gentl", index=0, properties={})
+        dlg = TriggerConfigDialog(cam)
+        qtbot.addWidget(dlg)
+
+        roles = [dlg.role_combo.itemData(i) for i in range(dlg.role_combo.count())]
+
+        assert roles == ["off", "external", "follower", "master"]
+        assert not dlg.selector_edit.isHidden()
+        assert not dlg.source_combo.isHidden()
+        assert not dlg.activation_combo.isHidden()
+        assert not dlg.output_line_edit.isHidden()
+        assert not dlg.output_source_edit.isHidden()
+        assert not dlg.strobe_polarity_combo.isHidden()
+        assert not dlg.strobe_operation_combo.isHidden()
+        assert not dlg.strobe_duration_spin.isHidden()
+        assert not dlg.strobe_delay_spin.isHidden()
+
+    @pytest.mark.gui
+    def test_basler_profile_shows_line_fields_but_hides_strobe_fields(self, qtbot):
+        cam = CameraSettings(backend="basler", index=0, properties={})
+        dlg = TriggerConfigDialog(cam)
+        qtbot.addWidget(dlg)
+
+        roles = [dlg.role_combo.itemData(i) for i in range(dlg.role_combo.count())]
+
+        assert roles == ["off", "external", "follower", "master"]
+        assert not dlg.output_line_edit.isHidden()
+        assert not dlg.output_source_edit.isHidden()
+        assert dlg.strobe_polarity_combo.isHidden()
+        assert dlg.strobe_operation_combo.isHidden()
+        assert dlg.strobe_duration_spin.isHidden()
+        assert dlg.strobe_delay_spin.isHidden()
+
+    @pytest.mark.gui
+    def test_role_changes_enable_input_and_output_fields(self, qtbot):
+        cam = CameraSettings(backend="gentl", index=0, properties={})
+        dlg = TriggerConfigDialog(cam)
+        qtbot.addWidget(dlg)
+
+        dlg.role_combo.setCurrentIndex(dlg.role_combo.findData("off"))
+        assert not dlg.selector_edit.isEnabled()
+        assert not dlg.source_combo.isEnabled()
+        assert not dlg.output_line_edit.isEnabled()
+
+        dlg.role_combo.setCurrentIndex(dlg.role_combo.findData("external"))
+        assert dlg.selector_edit.isEnabled()
+        assert dlg.source_combo.isEnabled()
+        assert dlg.activation_combo.isEnabled()
+        assert not dlg.output_line_edit.isEnabled()
+
+        dlg.role_combo.setCurrentIndex(dlg.role_combo.findData("master"))
+        assert not dlg.selector_edit.isEnabled()
+        assert not dlg.source_combo.isEnabled()
+        assert dlg.output_line_edit.isEnabled()
+        assert dlg.output_source_edit.isEnabled()
+        assert dlg.strobe_polarity_combo.isEnabled()
+        assert dlg.strobe_delay_spin.isEnabled()
+
+    @pytest.mark.gui
+    def test_fixed_duration_enables_strobe_duration_only_for_master(self, qtbot):
+        cam = CameraSettings(backend="gentl", index=0, properties={})
+        dlg = TriggerConfigDialog(cam)
+        qtbot.addWidget(dlg)
+
+        dlg.role_combo.setCurrentIndex(dlg.role_combo.findData("master"))
+        dlg.strobe_operation_combo.setCurrentIndex(dlg.strobe_operation_combo.findData("FixedDuration"))
+
+        assert dlg.strobe_duration_spin.isEnabled()
+
+        dlg.role_combo.setCurrentIndex(dlg.role_combo.findData("external"))
+
+        assert not dlg.strobe_duration_spin.isEnabled()
+
+
+class TestTriggerConfigDialogModelRoundtrip:
+    @pytest.mark.gui
+    def test_loads_existing_trigger_settings(self, qtbot):
+        cam = CameraSettings(
+            backend="gentl",
+            index=0,
+            properties={
+                "gentl": {
+                    "trigger": {
+                        "role": "external",
+                        "selector": "FrameStart",
+                        "source": "Line1",
+                        "activation": "FallingEdge",
+                        "timeout": 0.25,
+                        "strict": True,
+                    }
+                }
+            },
+        )
+
+        dlg = TriggerConfigDialog(cam)
+        qtbot.addWidget(dlg)
+
+        assert dlg.role_combo.currentData() == "external"
+        assert dlg.selector_edit.text() == "FrameStart"
+        assert dlg.source_combo.currentText() == "Line1"
+        assert dlg.activation_combo.currentData() == "FallingEdge"
+        assert dlg.timeout_spin.value() == pytest.approx(0.25)
+        assert dlg.strict_checkbox.isChecked()
+
+    @pytest.mark.gui
+    def test_accept_external_writes_trigger_payload_to_backend_namespace(self, qtbot):
+        cam = CameraSettings(backend="gentl", index=0, properties={})
+        dlg = TriggerConfigDialog(cam)
+        qtbot.addWidget(dlg)
+
+        dlg.role_combo.setCurrentIndex(dlg.role_combo.findData("external"))
+        dlg.selector_edit.setText("FrameStart")
+        dlg.source_combo.setCurrentText("Line1")
+        dlg.activation_combo.setCurrentIndex(dlg.activation_combo.findData("FallingEdge"))
+        dlg.timeout_spin.setValue(0.5)
+        dlg.strict_checkbox.setChecked(True)
+
+        with qtbot.waitSignal(dlg.accepted, timeout=1000):
+            dlg._accept()
+
+        trigger = dlg.camera_settings.properties["gentl"]["trigger"]
+
+        assert trigger["role"] == "external"
+        assert trigger["selector"] == "FrameStart"
+        assert trigger["source"] == "Line1"
+        assert trigger["activation"] == "FallingEdge"
+        assert trigger["timeout"] == pytest.approx(0.5)
+        assert trigger["strict"] is True
+
+    @pytest.mark.gui
+    def test_accept_off_clears_timeout(self, qtbot):
+        cam = CameraSettings(
+            backend="gentl",
+            index=0,
+            properties={"gentl": {"trigger": {"role": "external", "timeout": 2.0}}},
+        )
+        dlg = TriggerConfigDialog(cam)
+        qtbot.addWidget(dlg)
+
+        dlg.role_combo.setCurrentIndex(dlg.role_combo.findData("off"))
+        dlg.timeout_spin.setValue(1.25)
+
+        with qtbot.waitSignal(dlg.accepted, timeout=1000):
+            dlg._accept()
+
+        trigger = dlg.camera_settings.properties["gentl"]["trigger"]
+
+        assert trigger["role"] == "off"
+        assert trigger.get("timeout") is None
+
+    @pytest.mark.gui
+    def test_accept_master_gentl_includes_strobe_values(self, qtbot):
+        cam = CameraSettings(backend="gentl", index=0, properties={})
+        dlg = TriggerConfigDialog(cam)
+        qtbot.addWidget(dlg)
+
+        dlg.role_combo.setCurrentIndex(dlg.role_combo.findData("master"))
+        dlg.output_line_edit.setText("Line2")
+        dlg.output_source_edit.setText("ExposureActive")
+        dlg.strobe_polarity_combo.setCurrentIndex(dlg.strobe_polarity_combo.findData("ActiveLow"))
+        dlg.strobe_operation_combo.setCurrentIndex(dlg.strobe_operation_combo.findData("FixedDuration"))
+        dlg.strobe_duration_spin.setValue(1200)
+        dlg.strobe_delay_spin.setValue(300)
+
+        with qtbot.waitSignal(dlg.accepted, timeout=1000):
+            dlg._accept()
+
+        trigger = dlg.camera_settings.properties["gentl"]["trigger"]
+
+        assert trigger["role"] == "master"
+        assert trigger["output_line"] == "Line2"
+        assert trigger["output_source"] == "ExposureActive"
+        assert trigger["strobe_polarity"] == "ActiveLow"
+        assert trigger["strobe_operation"] == "FixedDuration"
+        assert trigger["strobe_duration"] == 1200
+        assert trigger["strobe_delay"] == 300
+
+    @pytest.mark.gui
+    def test_accept_master_basler_does_not_add_strobe_values(self, qtbot):
+        cam = CameraSettings(backend="basler", index=0, properties={})
+        dlg = TriggerConfigDialog(cam)
+        qtbot.addWidget(dlg)
+
+        dlg.role_combo.setCurrentIndex(dlg.role_combo.findData("master"))
+        dlg.strobe_duration_spin.setValue(1200)
+        dlg.strobe_delay_spin.setValue(300)
+
+        with qtbot.waitSignal(dlg.accepted, timeout=1000):
+            dlg._accept()
+
+        trigger = dlg.camera_settings.properties["basler"]["trigger"]
+
+        assert trigger["role"] == "master"
+        assert "strobe_duration" not in trigger
+        assert "strobe_delay" not in trigger
+        assert "strobe_polarity" not in trigger
+        assert "strobe_operation" not in trigger