@@ -13,7 +13,7 @@ jobs:
   check-and-bump:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
 
       - name: Get latest LoopStructural release
         id: latest
@@ -23,7 +23,11 @@ jobs:
           # can return whichever component's release was published last, not
           # necessarily the LoopStructural package. Read the manifest instead —
           # it maps package name to version unambiguously.
-          latest=$(curl -s https://raw.githubusercontent.com/Loop3D/LoopStructural/master/.release-please-manifest.json | jq -r '.["LoopStructural"]')
+          latest=$(curl -fsS https://raw.githubusercontent.com/Loop3D/LoopStructural/master/.release-please-manifest.json | jq -r '.["LoopStructural"] // empty')
+          if ! [[ "$latest" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
+            echo "::error::Could not read a valid LoopStructural version from the release manifest (got '${latest}')."
+            exit 1
+          fi
           echo "version=$latest" >> "$GITHUB_OUTPUT"
 
       - name: Bump pins if minor version changed
@@ -44,7 +48,7 @@ jobs:
 
       - name: Open pull request
         if: steps.bump.outputs.changed == '1'
-        uses: peter-evans/create-pull-request@v6
+        uses: peter-evans/create-pull-request@v8
         with:
           commit-message: "fix: bump LoopStructural pin to ${{ steps.latest.outputs.version }}"
           title: "Bump LoopStructural pin to ${{ steps.latest.outputs.version }}"
 
@@ -20,13 +20,19 @@ on:
 
 env:
   PROJECT_FOLDER: "loopstructural"
-  PYTHON_VERSION: 3.9
 
 
 jobs:
   tests-unit:
     runs-on: ubuntu-latest
 
+    # 3.10 is the oldest Python of a supported QGIS build (3.44 LTR on Ubuntu 22.04).
+    # 3.12 is the Python of the QGIS Windows (OSGeo4W) installers.
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ["3.10", "3.12"]
+
     steps:
       - name: Get source code
         uses: actions/checkout@v7
@@ -36,7 +42,7 @@ jobs:
         with:
           cache: "pip"
           cache-dependency-path: "requirements/testing.txt"
-          python-version: ${{ env.PYTHON_VERSION }}
+          python-version: ${{ matrix.python-version }}
 
       - name: Install Python requirements
         run: |
@@ -54,7 +60,7 @@ jobs:
         if: always()
         uses: actions/upload-artifact@v7
         with:
-          name: coverage-unit
+          name: coverage-unit-py${{ matrix.python-version }}
           path: |
             coverage.xml
             htmlcov/
@@ -64,8 +70,14 @@ jobs:
   test-qgis:
     runs-on: ubuntu-latest
 
+    # 3.44-jammy: the current LTR, with Python 3.10. 4.2: the latest release, with Qt6.
+    strategy:
+      fail-fast: false
+      matrix:
+        qgis-image: ["3.44-jammy", "4.2"]
+
     container:
-      image: qgis/qgis:release-3_28
+      image: qgis/qgis:${{ matrix.qgis-image }}
       env:
         CI: true
         DISPLAY: ":1"
@@ -88,13 +100,20 @@ jobs:
           set -e
           apt-get update
           DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
-            build-essential gdal-bin libgdal-dev proj-bin libproj-dev libgeos-dev python3-dev xvfb
+            build-essential gdal-bin libgdal-dev proj-bin libproj-dev libgeos-dev python3-dev python3-venv xvfb
           rm -rf /var/lib/apt/lists/*
 
       - name: Setup plugin
         run: bash /tests_directory/scripts/qgis_setup.sh loopstructural
 
 
+      # Install into a venv that can see the system packages (QGIS). Then pip and setuptools
+      # can be upgraded without changes to the Debian packages (PEP 668, no RECORD files).
+      - name: Create virtual environment
+        run: |
+          python3 -m venv --system-site-packages /opt/venv
+          echo "/opt/venv/bin" >> "$GITHUB_PATH"
+
       - name: Install Python requirements
         run: |
           python3 -m pip install -U pip setuptools wheel
@@ -114,7 +133,7 @@ jobs:
         if: always()
         uses: actions/upload-artifact@v7
         with:
-          name: coverage-qgis
+          name: coverage-qgis-${{ matrix.qgis-image }}
           path: |
             coverage.xml
             htmlcov/
 
@@ -194,7 +194,8 @@ of date with its contacts, and update it at build time.
 3. Each step has a check function. The step header shows its result.
 4. Use QGIS widgets and theme icons: `QgsColorButton`, `QgsCollapsibleGroupBox`,
    `QgsApplication.getThemeIcon`. Do not use emoji as icons.
-5. Do not put a scroll area around a widget that scrolls.
+5. A list that scrolls must fill its tab. If the tab has an outer scroll area,
+   the scroll area must scroll only when the dock is shorter than the tab.
 6. Derived data records its inputs. The UI shows when it is out of date. A
    model build never uses out-of-date derived data.
 
@@ -275,7 +276,8 @@ styling) is merged.
 - [x] Rows: use `QgsColorButton`, a theme delete icon, and no repeated
       "Thickness:" label. Give unconformity rows a different style.
 - [x] Show text in the empty list.
-- [x] Remove the outer scroll area from the tab.
+- [x] Make the unit list fill the tab. The outer scroll area scrolls only in a
+      dock that is shorter than the column.
 
 Files: `stratigraphic_column/*.py`, `stratigraphic_column/*.ui`,
 `geological_history_tab.py`.
 
@@ -128,7 +128,7 @@ additional-builtins=
 [FORMAT]
 
 # Maximum number of characters on a single line.
-max-line-length=88
+max-line-length=100
 
 # Regexp for a line that is allowed to be longer than the limit.
 ignore-long-lines=^\s*(# )?<?https?://\S+>?$
 
@@ -74,9 +74,14 @@ def start_background_task(
     on_progress,
     on_finished,
     on_error,
+    modal=False,
 ):
-    """Start `target(progress_callback)` on a background QThread, with a
-    non-modal indeterminate QProgressDialog parented to `widget`.
+    """Start `target(progress_callback)` on a background QThread, with an
+    indeterminate QProgressDialog parented to `widget`.
+
+    The dialog is non-modal unless `modal` is True. A modal dialog blocks the
+    window of `widget` until the task ends, so the user cannot start other
+    work (for example a model build) that changes the data of the task.
 
     `on_progress`, `on_finished` and `on_error` MUST be bound methods of
     `widget` (e.g. `self._on_sampler_finished`), never lambdas/closures --
@@ -90,7 +95,9 @@ def start_background_task(
     the thread is running, the thread is destroyed with it.
     """
     progress_dialog = QProgressDialog(initial_label, "Cancel", 0, 0, widget)
-    progress_dialog.setWindowModality(Qt.WindowModality.NonModal)
+    progress_dialog.setWindowModality(
+        Qt.WindowModality.WindowModal if modal else Qt.WindowModality.NonModal
+    )
     progress_dialog.setWindowTitle(title)
     progress_dialog.setCancelButton(None)
     progress_dialog.setMinimumDuration(0)
 
@@ -247,18 +247,9 @@ def _run_extractor(self):
         unit_name_field = self.unitNameFieldComboBox.currentField()
         adopt_geology_role(self.data_manager, geology=geology, unit_field=unit_name_field)
         # The inputs of this run, read before the run starts. A change during
-        # the run makes the result out of date.
-        self._run_inputs = (
-            self.data_manager.basal_contacts_inputs(
-                geology=geology,
-                unit_field=unit_name_field,
-                faults=self.faultsLayerComboBox.currentLayer(),
-                ignore_units=self._units_from_line_edit(self.ignoreUnitsLineEdit),
-                override_units=self._units_from_line_edit(self.basalOverrideUnitsLineEdit),
-            )
-            if self.data_manager
-            else None
-        )
+        # the run makes the result out of date. These are read from the same
+        # source as the status check, after the settings were saved.
+        self._run_inputs = self.data_manager.basal_contacts_inputs() if self.data_manager else None
 
         self.setEnabled(False)
         self._extractor_thread, self._extractor_worker, self._extractor_progress = (
 
@@ -171,11 +171,11 @@ def _run_painter(self):
                 adopt_geology_role(
                     self.data_manager, geology=geology_layer, unit_field=unit_name_field
                 )
-                self.data_manager.derived.record(
-                    derived_data.STYLED_FIELDS,
-                    inputs=self.data_manager.styled_fields_inputs(),
-                    detail={'layer': geology_layer.name(), 'field': unit_name_field},
-                )
+                run_inputs = self.data_manager.styled_fields_inputs()
+            # The layer that has the field at the end: the geology layer, or
+            # its styled copy
+            styled_layer = geology_layer
+            ramp_name = None
 
             # If requested, duplicate layer and apply style using selected colour ramp
             try:
@@ -242,6 +242,7 @@ def _run_painter(self):
                     mem_dp.addFeatures(new_feats)
                     mem_layer.updateExtents()
                     QgsProject.instance().addMapLayer(mem_layer)
+                    styled_layer = mem_layer
                 except Exception as e:
                     QMessageBox.warning(self, 'Duplicate Layer', f'Failed to create copy: {e}')
                     return False
@@ -346,6 +347,18 @@ def _run_painter(self):
                         self, 'Duplicate Layer', f'Failed to apply graduated styling: {e}'
                     )
 
+            if self.data_manager:
+                # Update writes the field again to the layer that is recorded
+                self.data_manager.derived.record(
+                    derived_data.STYLED_FIELDS,
+                    inputs=run_inputs,
+                    detail={
+                        'layer': styled_layer.name(),
+                        'field': unit_name_field,
+                        'ramp': ramp_name,
+                    },
+                )
+
         except Exception as e:
             QMessageBox.warning(self, 'Paint Stratigraphic Order', f'Operation failed: {e}')
             return False
 
@@ -337,6 +337,7 @@ def _persist_selection(self):
             ),
             'calculator_type': self.calculatorTypeComboBox.currentText(),
             'calculator_type_index': self.calculatorTypeComboBox.currentIndex(),
+            'orientation_type': self.orientationTypeComboBox.currentText(),
             'orientation_type_index': self.orientationTypeComboBox.currentIndex(),
             'max_line_length': self.maxLineLengthSpinBox.value(),
             'sampling_frequency': self.samplingFrequencySpinBox.value(),
@@ -408,19 +409,9 @@ def _run_calculator(self):
             unit_field=self.unitNameFieldComboBox.currentField(),
         )
         # The inputs of this run, read before the run starts. A change during
-        # the run makes the result out of date.
-        self._run_inputs = (
-            self.data_manager.thickness_inputs(
-                geology=self.geologyLayerComboBox.currentLayer(),
-                unit_field=self.unitNameFieldComboBox.currentField(),
-                contacts_layer=self.basalContactsComboBox.currentLayer(),
-                calculator_type=calculator_type,
-                structure=self.structureLayerComboBox.currentLayer(),
-                cross_sections=self.crossSectionLayerComboBox.currentLayer(),
-            )
-            if self.data_manager
-            else None
-        )
+        # the run makes the result out of date. These are read from the same
+        # source as the status check, after the settings were saved.
+        self._run_inputs = self.data_manager.thickness_inputs() if self.data_manager else None
 
         def target(progress_callback):
             return calculate_thickness(updater=progress_callback, **params)
@@ -466,8 +457,7 @@ def _on_calculator_finished(self, result):
             # A thickness that the user typed does not change.
             if thicknesses is not None and self.data_manager:
                 skipped = self._apply_thicknesses(thicknesses)
-            if self.data_manager and getattr(self, '_run_inputs', None) is not None:
-                self.data_manager.derived.record(derived_data.THICKNESS, inputs=self._run_inputs)
+            self._record_run()
             # if thicknesses is not None:
             #     addGeoDataFrameToproject(thicknesses, "Thickness Results")
             if lines is not None:
@@ -483,6 +473,7 @@ def _on_calculator_finished(self, result):
             self.task_succeeded.emit()
             return
 
+        self._record_run()
         if hasattr(result, 'geometry'):
             addGeoDataFrameToproject(result, "Thickness Results")
             push_success(
@@ -495,6 +486,11 @@ def _on_calculator_finished(self, result):
         push_success("Thickness Calculator", f"Thickness calculation completed: {result}")
         self.task_succeeded.emit()
 
+    def _record_run(self):
+        """Record the inputs of the run that finished."""
+        if self.data_manager and getattr(self, '_run_inputs', None) is not None:
+            self.data_manager.derived.record(derived_data.THICKNESS, inputs=self._run_inputs)
+
     def _apply_thicknesses(self, thicknesses):
         """Set the calculated thicknesses on the units of the column.
 
 
@@ -11,7 +11,9 @@ def push_success(title: str, text: str, duration: int = 5):
     confirmation before a destructive action.
     """
     if iface is not None:
-        iface.messageBar().pushMessage(title, text, level=Qgis.MessageLevel.Success, duration=duration)
+        iface.messageBar().pushMessage(
+            title, text, level=Qgis.MessageLevel.Success, duration=duration
+        )
     else:
         # No main window, for example in the tests
         QgsMessageLog.logMessage(f"{title}: {text}", "LoopStructural", Qgis.MessageLevel.Success)
@@ -28,6 +30,8 @@ def push_info(title: str, text: str, duration: int = 5):
 def push_warning(title: str, text: str, duration: int = 10):
     """Show a warning in the message bar of QGIS, for a result that is not an error."""
     if iface is not None:
-        iface.messageBar().pushMessage(title, text, level=Qgis.MessageLevel.Warning, duration=duration)
+        iface.messageBar().pushMessage(
+            title, text, level=Qgis.MessageLevel.Warning, duration=duration
+        )
     else:
         QgsMessageLog.logMessage(f"{title}: {text}", "LoopStructural", Qgis.MessageLevel.Warning)
@@ -70,13 +70,19 @@ def __init__(self, parent=None, *, model_manager=None):
         size = QGroupBox("Size")
         form = QFormLayout(size)
         self.major_input = _spin(0.01, 1e9)
-        self.major_input.setToolTip("How far the fault extends along its strike.")
+        self.major_input.setToolTip(
+            "The full length of the fault in its plane, at right angles to the slip. "
+            "With a pitch of 90 (dip slip), this is along the strike."
+        )
         self.intermediate_input = _spin(0.01, 1e9)
-        self.intermediate_input.setToolTip("How far the fault extends down its dip.")
+        self.intermediate_input.setToolTip(
+            "How far the fault extends from the centre in the direction of the slip. "
+            "With a pitch of 90 (dip slip), this is down the dip."
+        )
         self.minor_input = _spin(0.01, 1e9)
         self.minor_input.setToolTip("How far the fault changes the field, across the fault.")
-        form.addRow("Length along strike:", self.major_input)
-        form.addRow("Extent down dip:", self.intermediate_input)
+        form.addRow("Length across the slip:", self.major_input)
+        form.addRow("Extent along the slip:", self.intermediate_input)
         form.addRow("Influence distance:", self.minor_input)
         layout.addWidget(size)