added a bscan extension

MultiDeviceLibreVnaService only exposes the 2x4 virtual combo matrix on
its own USB transport. When a physical GPIO switch sits on the master
stimulus and/or slave receiver path, the effective matrix is wider than
that. SwitchedMatrixRadarService wraps the inner service and drives the
extra switch(es) between acquire_collection calls, widening the combo
matrix by the physical position counts (matrix_output_switch_positions /
matrix_input_switch_positions in RunConfigModel).

Combo-matrix construction was centralized into
RunConfigModel.build_runtime_combos() so the GUI, workflows, and codec
all derive the same widened matrix instead of each computing its own
version of the virtual 2x4 layout.

.gitignore

@@ -226,4 +226,5 @@ python_app/runtime
 SHARE_INTERNET_TO_PI.md
 
 CLAUDE.md
-./docs
+docs/
+test_end_2/

python_app/gui/app_window.py

@@ -274,7 +274,7 @@ class AppWindow(
 
     def _init_history_state(self) -> None:
         """Initialize runtime history buffers and render-cache state."""
-        bscan_history_limit = self._history_limit_from_config()
+        bscan_cpp_replay_window = self._cpp_bscan_replay_window_from_config()
         save_history_limit = self._save_history_limit_from_config()
         self._raw_history: deque[SweepCollection] = deque(maxlen=save_history_limit)
         self._pre_history: deque[SweepCollection] = deque(maxlen=save_history_limit)
@@ -282,7 +282,7 @@ class AppWindow(
 
         # Sequence id must survive GUI restarts so history commands stay monotonic.
         self._history_command_seq = self._load_history_command_seq(self._live_config_writer.path)
-        self._bscan_history_limit = bscan_history_limit
+        self._bscan_cpp_replay_window = bscan_cpp_replay_window
         self._bscan_history_by_combo = {}
         self._bscan_depth_axis_by_combo = {}
         self._bscan_history_floor_collection_id = 0
@@ -305,9 +305,9 @@ class AppWindow(
         self._active_processing_mode = "pass_through"
         self._radar_limits: dict[str, float | int] | None = None
 
-    def _history_limit_from_config(self) -> int:
-        """Return B-scan render history limit derived from configured ring capacities."""
-        return self._history_limit_for_config(self._defaults_config)
+    def _cpp_bscan_replay_window_from_config(self) -> int:
+        """Return the C++ B-scan replay window for the active config."""
+        return self._cpp_bscan_replay_window_for_config(self._defaults_config)
 
     def _save_history_limit_from_config(self) -> int:
         """Return maxlen for GUI snapshot-save deques (independent of ring capacities)."""

python_app/gui/controllers/app_window_config/profile_io_mixin.py

@@ -61,7 +61,7 @@ class AppWindowConfigProfileIOMixin:
         """Return the canonical virtual combo matrix shown for matrix-mode radars."""
         return ",".join(
             f"{int(combo.input)}:{int(combo.output)}"
-            for combo in RunConfigModel.build_matrix_radar_virtual_combos()
+            for combo in self._defaults_config.build_runtime_combos()
         )
 
     def _sync_pass_through_y_controls(self) -> None:
@@ -121,15 +121,15 @@ class AppWindowConfigProfileIOMixin:
 
         Save-side deques use a config-independent limit so that processing-side
         ring capacities can stay small without truncating the save buffer. The
-        B-scan render limit still follows ring capacities to keep plot updates
-        responsive.
+        C++ replay window still follows ring capacities, since it bounds how much
+        of the history the processor can re-publish coherently.
         """
         save_history_limit = self._save_history_limit_for_config(config)
-        bscan_history_limit = self._history_limit_for_config(config)
+        bscan_cpp_replay_window = self._cpp_bscan_replay_window_for_config(config)
         self._raw_history = deque(self._raw_history, maxlen=save_history_limit)
         self._pre_history = deque(self._pre_history, maxlen=save_history_limit)
         self._result_history = deque(self._result_history, maxlen=save_history_limit)
-        self._bscan_history_limit = bscan_history_limit
+        self._bscan_cpp_replay_window = bscan_cpp_replay_window
         self._clear_bscan_plot_history()
 
     def _save_current_config(self) -> None:
@@ -283,6 +283,7 @@ class AppWindowConfigProfileIOMixin:
             self._bscan_start_freq_mhz,
             self._bscan_stop_freq_mhz,
             self._bscan_subtract_mean_ascan,
+            self._bscan_history_window,
             self._gpr_relative_permittivity,
             self._gpr_tx_geometry_input,
             self._gpr_rx_geometry_input,
@@ -438,6 +439,7 @@ class AppWindowConfigProfileIOMixin:
             self._bscan_start_freq_mhz.setValue(float(gui_state.processing.bscan.start_freq_mhz))
             self._bscan_stop_freq_mhz.setValue(float(gui_state.processing.bscan.stop_freq_mhz))
             self._bscan_subtract_mean_ascan.setChecked(bool(gui_state.processing.bscan.subtract_mean_ascan))
+            self._bscan_history_window.setValue(int(gui_state.processing.bscan.history_window_scans))
 
             self._gpr_relative_permittivity.setValue(float(config.gpr.relative_permittivity))
             self._gpr_tx_geometry_input.setPlainText(

python_app/gui/controllers/app_window_config/state_builders.py

@@ -34,6 +34,13 @@ from python_app.storage.npz_store import radar_key_from_config
 # history without touching the processing-side ring sizes.
 GUI_SAVE_HISTORY_LIMIT: int = 1000
 
+# Mirror of `kBscanReplayWindow` in
+# data_acq_and_processing/processing/data_processor/src/data_processor.cpp. When a
+# live B-scan setting changes, the C++ processor re-processes and re-publishes only
+# this many of the newest collections; anything older keeps the payload it was first
+# computed with. Keep the two constants in sync.
+CPP_BSCAN_REPLAY_WINDOW: int = 50
+
 
 class AppWindowConfigStateBuildersMixin:
     """Build stable and GUI-only config models from current widget state."""
@@ -125,7 +132,7 @@ class AppWindowConfigStateBuildersMixin:
         if config.is_matrix_radar:
             return ",".join(
                 f"{int(combo.input)}:{int(combo.output)}"
-                for combo in RunConfigModel.build_matrix_radar_virtual_combos()
+                for combo in config.build_runtime_combos()
             )
         combos = list(config.combos)
         full_combos = config.build_full_combos(config.input_switch.positions, config.output_switch.positions)
@@ -163,14 +170,24 @@ class AppWindowConfigStateBuildersMixin:
         return (min(x_values) - margin_m, max(x_values) + margin_m)
 
     @staticmethod
-    def _history_limit_for_config(config: RunConfigModel) -> int:
-        """Return B-scan render history limit derived from config ring capacities."""
+    def _cpp_bscan_replay_window_for_config(config: RunConfigModel) -> int:
+        """Return how many newest collections the C++ processor re-processes on a
+        live B-scan settings change.
+
+        Deliberately reproduces `replay_history_limit()` in `data_processor.cpp`
+        formula-for-formula. The ring capacities matter because `ShmRing` overwrites
+        the oldest unread slot on overflow, so a replay burst must fit in the results
+        ring for the GUI to receive all of it.
+
+        This is the single place to change if the replay window ever becomes
+        configurable on the C++ side.
+        """
         return max(
             1,
             min(
-                int(config.rings.raw_tap.capacity),
-                int(config.rings.preprocessed_tap.capacity),
+                int(config.rings.preprocessed.capacity),
                 int(config.rings.results.capacity),
+                CPP_BSCAN_REPLAY_WINDOW,
             ),
         )
 
@@ -180,7 +197,7 @@ class AppWindowConfigStateBuildersMixin:
 
         Independent of ring capacities — see :data:`GUI_SAVE_HISTORY_LIMIT`.
         The `config` argument is kept for symmetry with
-        :meth:`_history_limit_for_config` and possible future per-profile
+        :meth:`_cpp_bscan_replay_window_for_config` and possible future per-profile
         overrides.
         """
         del config
@@ -344,6 +361,7 @@ class AppWindowConfigStateBuildersMixin:
                     start_freq_mhz=float(self._bscan_start_freq_mhz.value()),
                     stop_freq_mhz=float(self._bscan_stop_freq_mhz.value()),
                     subtract_mean_ascan=bool(self._bscan_subtract_mean_ascan.isChecked()),
+                    history_window_scans=int(self._bscan_history_window.value()),
                 ),
                 gpr=GuiGprStateModel(
                     input_positions=self._gpr_input_positions_input.text().strip(),

python_app/gui/controllers/app_window_plot/bscan_plot_mixin.py

@@ -52,6 +52,7 @@ def build_bscan_signature(
         floor_collection_id=floor_collection_id,
     )
     return (
+        int(history_limit),
         str(live_config.bscan_axis),
         str(live_config.bscan_channel),
         float(live_config.bscan_cut_m),
@@ -213,6 +214,7 @@ class AppWindowBscanPlotMixin:
         depth_max = float(np.max(depth_axis))
         depth_span = max(depth_max - depth_min, 1e-6)
         sweep_count = sweeps.shape[0]
+        self._warn_if_bscan_exceeds_replay_window(sweep_count)
         sweep_width = float(max(sweep_count, 1))
         x_min = 0.5
         x_max = x_min + sweep_width
@@ -236,9 +238,52 @@ class AppWindowBscanPlotMixin:
         )
         return True
 
+    def _warn_if_bscan_exceeds_replay_window(self, sweep_count: int) -> None:
+        """Warn once when the image reaches past what the C++ processor can replay.
+
+        Beyond that window a frame keeps the payload it was first computed with, so
+        editing Gain / Cut / Max depth / Start-Stop MHz silently leaves the older
+        columns on their previous settings — the image mixes two parameter sets.
+        """
+        replay_window = int(self._bscan_cpp_replay_window)
+        if sweep_count <= replay_window:
+            return
+
+        stale_count = sweep_count - replay_window
+        self._log_warning(
+            f"B-scan shows {sweep_count} sweeps but the processor replays only the newest "
+            f"{replay_window}; the older {stale_count} keep the settings they were captured with.",
+            details=(
+                "Changing Gain / Cut m / Max depth m / Start MHz / Stop MHz re-processes "
+                f"only the newest {replay_window} sweeps.\n"
+                f"Reduce 'Scans to show (stopped)' to {replay_window} for an image that is "
+                "coherent across every column."
+            ),
+            # Keyed on the operator-controlled window, not the live column count, so
+            # that repeated "Remove Last" in stopped mode does not re-warn every click.
+            once_key=(
+                f"bscan_window_exceeds_replay_{replay_window}_"
+                f"{self._bscan_display_window_scans()}"
+            ),
+        )
+
+    def _bscan_display_window_scans(self) -> int:
+        """Return how many past sweeps the B-scan should render right now.
+
+        While acquisition runs the window stays at the C++ replay window: results
+        arrive continuously, the whole history is rebuilt on every new one, and a
+        1000-wide rebuild on the live path would cost ~20x per frame.
+
+        Once stopped, the operator reviews a frozen history, so the user-configured
+        window applies and may reach back over the whole GUI result deque.
+        """
+        if self._supervisor.is_running():
+            return int(self._bscan_cpp_replay_window)
+        return max(1, int(self._bscan_history_window.value()))
+
     def _sync_bscan_history_from_results(self) -> None:
         """Rebuild B-scan history cache when live params or inputs changed."""
-        self._advance_bscan_floor_to_cpp_window()
+        self._advance_bscan_floor_to_display_window()
         signature = self._bscan_signature()
         if signature == self._bscan_render_signature:
             return
@@ -253,7 +298,7 @@ class AppWindowBscanPlotMixin:
             live_config=live_config,
             subtract_mean_ascan_enabled=bool(self._bscan_subtract_mean_ascan.isChecked()),
             result_history=result_history,
-            history_limit=self._bscan_history_limit,
+            history_limit=self._bscan_display_window_scans(),
             floor_collection_id=self._bscan_history_floor_collection_id,
         )
 
@@ -262,7 +307,7 @@ class AppWindowBscanPlotMixin:
         result_history = list(self._result_history)
         history_by_combo, depth_axis_by_combo = rebuild_bscan_history_from_results(
             result_history=result_history,
-            history_limit=self._bscan_history_limit,
+            history_limit=self._bscan_display_window_scans(),
             floor_collection_id=self._bscan_history_floor_collection_id,
         )
         self._bscan_history_by_combo = history_by_combo
@@ -351,29 +396,35 @@ class AppWindowBscanPlotMixin:
         self._bscan_depth_axis_by_combo.clear()
         self._bscan_render_signature = None
 
-    def _advance_bscan_floor_to_cpp_window(self) -> None:
-        """Clamp B-scan source history to C++ available replay window."""
-        if not self._result_history:
+    def _advance_bscan_floor_to_display_window(self) -> None:
+        """Clamp B-scan source history to the active display window.
+
+        The window counts RETAINED ENTRIES, so the floor is read off the n-th
+        newest entry rather than computed as `latest_id - window`. Collection ids
+        are not dense: the results ring overwrites unread slots when the producer
+        outruns the GUI poll loop, so the GUI keeps ids like 1..50, 81..130, ...
+        Subtracting the window from the newest id would then span far fewer than
+        `window` entries — asking for 150 sweeps yielded 87.
+
+        Recomputed unconditionally rather than ratcheted upwards: widening the
+        window in stopped mode must be able to LOWER the floor and bring older
+        frames back into view. A stale floor cannot survive this way either, so
+        the previous special case for collection ids restarting on a new C++ run
+        is no longer needed.
+        """
+        history = self._result_history
+        if not history:
             return
 
-        cpp_window_limit = min(
-            int(self._defaults_config.rings.preprocessed.capacity),
-            int(self._defaults_config.rings.results.capacity),
-        )
-        cpp_window_limit = max(1, cpp_window_limit)
-        latest_collection_id = int(self._result_history[-1].collection_id)
-        current_floor = int(self._bscan_history_floor_collection_id)
-
-        # Collection ids restart from 1 on new C++ run; release floor only while
-        # acquisition is running, so manual "remove last" behavior in stopped mode
-        # remains deterministic.
-        if latest_collection_id < current_floor and self._supervisor.is_running():
+        window = self._bscan_display_window_scans()
+        if len(history) <= window:
             self._bscan_history_floor_collection_id = 0
-            current_floor = 0
+            return
 
-        floor_candidate = max(0, latest_collection_id - cpp_window_limit)
-        if floor_candidate > current_floor:
-            self._bscan_history_floor_collection_id = floor_candidate
+        # `_result_tail` keeps entries with `collection_id > floor`, so sit the
+        # floor one below the oldest entry that still fits in the window.
+        oldest_visible = history[len(history) - window]
+        self._bscan_history_floor_collection_id = max(0, int(oldest_visible.collection_id) - 1)
 
     def _ensure_phase_view_box(self) -> pg.ViewBox:
         """Create or return secondary right-axis ViewBox for phase curves."""

python_app/gui/controllers/app_window_preprocess_mixin.py

@@ -10,7 +10,10 @@ from python_app.orchestration.preprocess_assets import (
     preprocess_asset_channel,
     preprocess_asset_display_name,
 )
-from python_app.workflows.kamil_adc_neutral_preprocess import build_kamil_adc_neutral_s21_sets
+from python_app.workflows.kamil_adc_neutral_preprocess import (
+    build_neutral_s21_sets,
+    supports_neutral_preprocess_sets,
+)
 from python_app.workflows.multi_radar_capture_workflow import (
     MultiRadarCaptureBatch,
     MultiRadarSequentialCaptureSession,
@@ -216,8 +219,8 @@ class AppWindowPreprocessMixin:
         dialog.undo_last_requested.connect(self._undo_last_capture)
         dialog.finalize_sequence_requested.connect(self._finalize_capture_sequence)
         dialog.abort_sequence_requested.connect(self._abort_capture_sequence)
-        dialog.create_kamil_adc_neutral_sets_requested.connect(self._create_kamil_adc_neutral_sets)
-        dialog.set_kamil_adc_neutral_sets_visible(self._defaults_config.is_kamil_adc)
+        dialog.create_neutral_sets_requested.connect(self._create_neutral_sets)
+        dialog.set_neutral_sets_visible(supports_neutral_preprocess_sets(self._defaults_config))
         dialog.set_radar_config_summary(
             directory_path=self._preprocess_radar_scan_summary.directory_path,
             json_file_count=self._preprocess_radar_scan_summary.json_file_count,
@@ -292,7 +295,7 @@ class AppWindowPreprocessMixin:
             f"{preprocess_asset_display_name(key)}={len(names)}"
             for key, names in available_sets.items()
         )
-        dialog.set_kamil_adc_neutral_sets_visible(self._defaults_config.is_kamil_adc)
+        dialog.set_neutral_sets_visible(supports_neutral_preprocess_sets(self._defaults_config))
         self._log(f"Preprocess set lists refreshed: radar_key={radar_key}, {available_counts}")
         if unavailable_selections:
             self._log_warning(
@@ -391,8 +394,8 @@ class AppWindowPreprocessMixin:
             self._show_exception(f"Failed to start {kind} sequence", exc)
             self._resume_pipeline_if_needed()
 
-    def _create_kamil_adc_neutral_sets(self) -> None:
-        """Save neutral S21 calibration/reference sets for the current Kamil ADC settings."""
+    def _create_neutral_sets(self) -> None:
+        """Save neutral S21 calibration/reference sets for the current radar settings."""
         if self._capture_session is not None:
             self._show_error(
                 "Cannot create neutral sets during active capture sequence",
@@ -409,8 +412,10 @@ class AppWindowPreprocessMixin:
         pipeline_was_paused = False
         try:
             config = self._build_config()
-            if not config.is_kamil_adc:
-                self._show_error("Neutral S21 sets are available only for kamil_adc")
+            if not supports_neutral_preprocess_sets(config):
+                self._show_error(
+                    "Neutral S21 sets are available only for kamil_adc and librevna_multi"
+                )
                 return
 
             radar_key = self._radar_key(config)
@@ -425,12 +430,12 @@ class AppWindowPreprocessMixin:
                 )
 
             if self._supervisor.is_running():
-                self._log("Pipeline paused for Kamil ADC neutral-set creation")
+                self._log("Pipeline paused for neutral-set creation")
                 self._stop_run()
                 pipeline_was_paused = True
 
-            calibration, reference = build_kamil_adc_neutral_s21_sets(config)
-            point_count = config.radar.kamil_adc.band.points
+            calibration, reference = build_neutral_s21_sets(config)
+            point_count = int(calibration.traces[0].frequency_hz.size)
             self._store.save_set("s21_calibration", radar_key, set_name, calibration)
             self._store.save_set("s21_reference", radar_key, set_name, reference)
 
@@ -445,11 +450,11 @@ class AppWindowPreprocessMixin:
                 f"Neutral S21 sets saved: {set_name} ({len(calibration.traces)} combos, {point_count} points)"
             )
             self._log(
-                "Kamil ADC neutral S21 sets saved: "
+                "Neutral S21 sets saved: "
                 f"set={set_name}, radar_key={radar_key}, combos={len(calibration.traces)}, points={point_count}"
             )
         except Exception as exc:  # noqa: BLE001
-            self._show_exception("Failed to create Kamil ADC neutral sets", exc)
+            self._show_exception("Failed to create neutral S21 sets", exc)
         finally:
             if pipeline_was_paused:
                 self._start_run()

python_app/gui/controllers/sections/processing_section.py

@@ -18,6 +18,7 @@ from PyQt6.QtWidgets import (
     QWidget,
 )
 
+from python_app.gui.controllers.app_window_config.state_builders import GUI_SAVE_HISTORY_LIMIT
 from python_app.gui.controllers.sections.layout_helpers import FormRow, build_two_column_form_widget
 
 
@@ -160,6 +161,15 @@ def build_processing_group(owner) -> QGroupBox:
     owner._bscan_subtract_mean_ascan = QCheckBox("Subtract mean A-scan")
     owner._bscan_subtract_mean_ascan.setChecked(bool(bscan_defaults.subtract_mean_ascan))
 
+    owner._bscan_history_window = QSpinBox()
+    owner._bscan_history_window.setMinimum(1)
+    owner._bscan_history_window.setMaximum(GUI_SAVE_HISTORY_LIMIT)
+    owner._bscan_history_window.setValue(int(bscan_defaults.history_window_scans))
+    owner._bscan_history_window.setToolTip(
+        "How many past sweeps the B-scan shows once acquisition is stopped. While "
+        "running, the window stays clamped to the C++ ring capacity."
+    )
+
     bscan_page = _build_processing_mode_page(
         owner._processing_mode_pages,
         [
@@ -169,6 +179,7 @@ def build_processing_group(owner) -> QGroupBox:
             ("Gain", owner._bscan_gain),
             ("Start MHz", owner._bscan_start_freq_mhz),
             ("Stop MHz", owner._bscan_stop_freq_mhz),
+            ("Scans to show (stopped)", owner._bscan_history_window),
             owner._bscan_subtract_mean_ascan,
         ],
         split_index=4,
@@ -569,6 +580,7 @@ def build_processing_group(owner) -> QGroupBox:
     owner._bscan_start_freq_mhz.valueChanged.connect(owner._on_processing_live_settings_changed)
     owner._bscan_stop_freq_mhz.valueChanged.connect(owner._on_processing_live_settings_changed)
     owner._bscan_subtract_mean_ascan.toggled.connect(owner._on_processing_live_settings_changed)
+    owner._bscan_history_window.valueChanged.connect(owner._on_processing_live_settings_changed)
     owner._gpr_input_positions_input.editingFinished.connect(owner._on_processing_live_settings_changed)
     owner._gpr_output_positions_input.editingFinished.connect(owner._on_processing_live_settings_changed)
     owner._gpr_min_depth_m.valueChanged.connect(owner._on_processing_live_settings_changed)

python_app/gui/preprocess_dialog.py

@@ -46,7 +46,7 @@ class PreprocessDialog(QDialog):
     undo_last_requested = pyqtSignal()
     finalize_sequence_requested = pyqtSignal()
     abort_sequence_requested = pyqtSignal()
-    create_kamil_adc_neutral_sets_requested = pyqtSignal()
+    create_neutral_sets_requested = pyqtSignal()
 
     def __init__(self, parent=None) -> None:
         """Initialize window metadata and compose dialog UI."""
@@ -92,17 +92,18 @@ class PreprocessDialog(QDialog):
         self._set_name_input = QLineEdit("set_001", group)
         refresh_button = QPushButton("Refresh Sets", group)
         refresh_button.clicked.connect(self.refresh_requested.emit)
-        self._kamil_adc_neutral_sets_button = QPushButton("Create Neutral S21 Sets", group)
-        self._kamil_adc_neutral_sets_button.setToolTip(
-            "Save S21 calibration=1 and S21 reference=0 for the current Kamil ADC settings."
+        self._neutral_sets_button = QPushButton("Create Neutral S21 Sets", group)
+        self._neutral_sets_button.setToolTip(
+            "Save S21 calibration=1 and S21 reference=0 for the current radar settings, "
+            "so the pipeline can run before any real calibration exists."
         )
-        self._kamil_adc_neutral_sets_button.clicked.connect(
-            self.create_kamil_adc_neutral_sets_requested.emit
+        self._neutral_sets_button.clicked.connect(
+            self.create_neutral_sets_requested.emit
         )
-        self._kamil_adc_neutral_sets_button.setVisible(False)
+        self._neutral_sets_button.setVisible(False)
         header_row.addWidget(QLabel("Set name"))
         header_row.addWidget(self._set_name_input, stretch=1)
-        header_row.addWidget(self._kamil_adc_neutral_sets_button)
+        header_row.addWidget(self._neutral_sets_button)
         header_row.addWidget(refresh_button)
         layout.addLayout(header_row)
         layout.addLayout(self._build_median_sweep_row(group))
@@ -413,10 +414,10 @@ class PreprocessDialog(QDialog):
         """Set short human-readable status line."""
         self._status_label.setText(message)
 
-    def set_kamil_adc_neutral_sets_visible(self, visible: bool) -> None:
-        """Show Kamil ADC neutral-set shortcut only in the matching radar mode."""
-        self._kamil_adc_neutral_sets_button.setVisible(bool(visible))
-        self._kamil_adc_neutral_sets_button.setEnabled(bool(visible))
+    def set_neutral_sets_visible(self, visible: bool) -> None:
+        """Show the neutral-set shortcut only for radar models that support it."""
+        self._neutral_sets_button.setVisible(bool(visible))
+        self._neutral_sets_button.setEnabled(bool(visible))
 
     def reset_preview(self) -> None:
         """Clear preview surfaces and restore default empty-state text when possible."""

python_app/hardware_full/librevna_multi_device_driver/controller.py

@@ -131,7 +131,14 @@ class MultiDeviceVnaController:
         if not self._reference_configuration_applied:
             self._configure_reference_clocks()
 
-        self._drain_all_received_packets()
+        drain_started_seconds = time.monotonic()
+        drained_packet_count = self._drain_all_received_packets()
+        logger.debug(
+            "timing: drain discarded %d stale packet(s) in %.2f ms (t=%.1f ms)",
+            drained_packet_count,
+            (time.monotonic() - drain_started_seconds) * 1e3,
+            time.monotonic() * 1e3,
+        )
 
         if (
             self._sweep_is_running
@@ -334,12 +341,16 @@ class MultiDeviceVnaController:
         self._sweep_is_running = True
         logger.debug("Sweep settings applied to all devices; sweep running")
 
-    def _drain_all_received_packets(self) -> None:
+    def _drain_all_received_packets(self) -> int:
         """Empty every device's received-packet queue, in parallel for 2+ devices.
 
         Concurrent draining keeps cross-device timing skew small so a hardware
         cycle wrap cannot slip between per-device drains and desynchronize the
         cycle counters.
+
+        Returns the total number of discarded packets, which the caller logs: a large
+        count means the host was far behind the free-running stream, a near-zero count
+        means the drain landed right after a sweep boundary.
         """
         # Drain every device queue in parallel rather than one after another:
         # serial drain leaves up to a few hundred microseconds of skew between
@@ -349,22 +360,31 @@ class MultiDeviceVnaController:
         # so concurrent get_nowait calls do not contend. A single device case
         # just runs inline to avoid the thread-spawn overhead.
         if len(self._all_devices) < 2:
-            for device_connection in self._all_devices:
-                device_connection.drain_received_packets()
-            return
+            return sum(
+                len(device_connection.drain_received_packets())
+                for device_connection in self._all_devices
+            )
+
+        drained_counts = [0] * len(self._all_devices)
+
+        def drain_one_device(device_index: int, device_connection: LibreVnaUsbBulkConnection) -> None:
+            """Drain one device's queue and record how many packets it held."""
+            drained_counts[device_index] = len(device_connection.drain_received_packets())
 
         drain_threads = [
             threading.Thread(
-                target=device_connection.drain_received_packets,
+                target=drain_one_device,
+                args=(device_index, device_connection),
                 name=f"drain-{device_connection.serial_number}",
                 daemon=True,
             )
-            for device_connection in self._all_devices
+            for device_index, device_connection in enumerate(self._all_devices)
         ]
         for drain_thread in drain_threads:
             drain_thread.start()
         for drain_thread in drain_threads:
             drain_thread.join()
+        return sum(drained_counts)
 
     @staticmethod
     def _normalize_master_stimulus_ports(master_stimulus_ports: Sequence[int]) -> tuple[int, ...]:

python_app/hardware_full/librevna_multi_device_driver/cycle_collection.py

@@ -441,6 +441,7 @@ def collect_complete_running_sweep_cycles(
     def build_cycle_tracking_handler(
         cycle_aware_handler: Callable[[ParsedVnaDatapoint, int], None],
         device_state: _DeviceCollectionState,
+        device_label: str = "device",
     ) -> Callable[[ParsedVnaDatapoint], bool]:
         """Wrap a cycle-aware handler with cross-device cycle tracking.
 
@@ -462,6 +463,11 @@ def collect_complete_running_sweep_cycles(
         cycle_tracking_state = {
             "current_cycle_index": 0,
             "synchronized": False,
+            # How many mid-sweep points were thrown away before the anchor was found.
+            # Near zero means the drain landed on a sweep boundary — the case where a
+            # stale point 0 could still have been in flight; a large count means the
+            # remainder of the in-progress sweep was safely skipped.
+            "pre_anchor_skipped": 0,
         }
 
         def handle_datapoint(parsed_datapoint: ParsedVnaDatapoint) -> bool:
@@ -475,6 +481,7 @@ def collect_complete_running_sweep_cycles(
 
             if not cycle_tracking_state["synchronized"]:
                 if current_point_index != 0:
+                    cycle_tracking_state["pre_anchor_skipped"] += 1
                     return False
                 # Candidate cycle 0. Commit it only once every device confirms it
                 # observed point 0 of the SAME physical sweep; otherwise reject the
@@ -484,6 +491,14 @@ def collect_complete_running_sweep_cycles(
                     report_cycle_misalignment()
                     return False
                 cycle_tracking_state["synchronized"] = True
+                logger.debug(
+                    "timing: %s anchored cycle 0 after skipping %d mid-sweep point(s) of %d "
+                    "(t=%.1f ms)",
+                    device_label,
+                    cycle_tracking_state["pre_anchor_skipped"],
+                    point_count,
+                    time.monotonic() * 1e3,
+                )
                 cycle_aware_handler(parsed_datapoint, 0)
                 return True
 
@@ -493,6 +508,12 @@ def collect_complete_running_sweep_cycles(
             # spurious wrap and desynchronize the cycle counter.
             if current_point_index == 0:
                 cycle_tracking_state["current_cycle_index"] += 1
+                logger.debug(
+                    "timing: %s first point of NEXT sweep arrived (cycle -> %d, t=%.1f ms)",
+                    device_label,
+                    cycle_tracking_state["current_cycle_index"],
+                    time.monotonic() * 1e3,
+                )
             current_cycle_index = cycle_tracking_state["current_cycle_index"]
             if current_cycle_index >= cycle_count:
                 # The sweep just wrapped past the final requested cycle, closing its
@@ -505,6 +526,14 @@ def collect_complete_running_sweep_cycles(
                 return False
 
             cycle_aware_handler(parsed_datapoint, current_cycle_index)
+            if current_point_index == point_count - 1:
+                logger.debug(
+                    "timing: %s last point of cycle %d arrived (index=%d, t=%.1f ms)",
+                    device_label,
+                    current_cycle_index,
+                    current_point_index,
+                    time.monotonic() * 1e3,
+                )
             return True
 
         return handle_datapoint
@@ -587,7 +616,9 @@ def collect_complete_running_sweep_cycles(
                             point_index,
                         ] = port_receiver_value
 
-        return build_cycle_tracking_handler(handle_slave_datapoint, device_state)
+        return build_cycle_tracking_handler(
+            handle_slave_datapoint, device_state, device_label=f"slave{slave_index}"
+        )
 
     master_device_state = _DeviceCollectionState()
     collection_threads = [
@@ -595,7 +626,9 @@ def collect_complete_running_sweep_cycles(
             target=collect_datapoints_from_device,
             args=(
                 master_device_connection,
-                build_cycle_tracking_handler(handle_master_datapoint, master_device_state),
+                build_cycle_tracking_handler(
+                    handle_master_datapoint, master_device_state, device_label="master"
+                ),
                 master_device_state,
             ),
             daemon=True,

python_app/hardware_full/matrix_radar_service.py

@@ -46,13 +46,31 @@ def create_matrix_radar_service(config: RunConfigModel) -> MatrixRadarService:
     if model == RunConfigModel.LIBREVNA_MULTI_MODEL:
         from python_app.hardware_full.multi_device_service import MultiDeviceLibreVnaService
 
-        return MultiDeviceLibreVnaService(
+        inner = MultiDeviceLibreVnaService(
             master_serial=config.radar.serial,
             slave_serials=list(config.radar.multi_device.slave_serials),
             force_external_reference=config.radar.multi_device.force_external_reference,
             recovery_attempts=config.radar.multi_device.recovery_attempts,
             backend_mode=config.radar.driver_mode,
         )
+        out_physical = config.matrix_output_switch_positions
+        in_physical = config.matrix_input_switch_positions
+        if out_physical <= 1 and in_physical <= 1:
+            return inner
+
+        from python_app.hardware_full.switched_matrix_radar_service import (
+            SwitchedMatrixRadarService,
+            build_physical_switch,
+        )
+
+        return SwitchedMatrixRadarService(
+            inner=inner,
+            output_switch=build_physical_switch(config.output_switch, out_physical, config.radar.driver_mode),
+            input_switch=build_physical_switch(config.input_switch, in_physical, config.radar.driver_mode),
+            inner_output_positions=RunConfigModel.MULTI_DEVICE_OUTPUT_POSITIONS,
+            inner_input_positions=RunConfigModel.MULTI_DEVICE_INPUT_POSITIONS,
+            settling_ms=config.runtime.settling_ms,
+        )
 
     if model == RunConfigModel.SN9000_MODEL:
         if config.radar.driver_mode != "native":

python_app/hardware_full/switch_service.py

@@ -66,6 +66,10 @@ class SwitchService:
         """Switch to requested position."""
         self._driver.switch_to(position)
 
+    def position_count(self) -> int:
+        """Return number of positions supported by the backend driver."""
+        return self._driver.position_count()
+
     @property
     def current_position(self) -> int:
         """Return current switch position reported by backend driver."""

python_app/hardware_full/switched_matrix_radar_service.py

@@ -0,0 +1,154 @@
+"""Matrix radar behind real GPIO switches on the stimulus and/or receiver path."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field, replace
+import logging
+import time
+
+from python_app.hardware_full.matrix_radar_service import MatrixRadarService
+from python_app.hardware_full.switch_service import SwitchService
+from python_app.models.dataset_model import ComboKey, SweepCollection, TraceData
+from python_app.models.run_config_model import RadarSweepModel, SwitchModel
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass(slots=True)
+class SwitchedMatrixRadarService:
+    """Widen a matrix radar's combo matrix with real switch positions.
+
+    Implements the ``MatrixRadarService`` protocol, so the producer and the
+    capture workflows treat it as an ordinary matrix radar that simply reports
+    more positions. The hardware sweep is never stopped: switches are only ever
+    driven BETWEEN ``acquire_collection`` calls, and the inner service's
+    free-running collection discards any partially swept cycle.
+    """
+
+    inner: MatrixRadarService
+    output_switch: SwitchService | None
+    input_switch: SwitchService | None
+    inner_output_positions: int
+    inner_input_positions: int
+    settling_ms: int = 0
+    # Monotonic end of the previous inner collection, so the DEBUG timing trace can
+    # report how long the gap between "sweep collected" and "switch driven" really is
+    # — that gap is where a stale in-flight point 0 can still slip past the drain.
+    _last_inner_end_ns: int = field(init=False, default=0, repr=False)
+
+    def open(self) -> None:
+        """Open the inner radar and both switches."""
+        self.inner.open()
+        if self.output_switch is not None:
+            self.output_switch.open()
+        if self.input_switch is not None:
+            self.input_switch.open()
+
+    def close(self) -> None:
+        """Close switches first, then the inner radar; never raises."""
+        for switch in (self.input_switch, self.output_switch):
+            if switch is not None:
+                try:
+                    switch.close()
+                except Exception as exc:  # noqa: BLE001 — shutdown path
+                    logger.warning("Switch close ignored error: %s", exc)
+        self.inner.close()
+
+    def configure(self, sweep: RadarSweepModel) -> None:
+        """Apply sweep settings to the inner radar."""
+        self.inner.configure(sweep)
+
+    def recover(self) -> None:
+        """Reconnect the inner radar; switches are not on the USB transport."""
+        self.inner.recover()
+
+    def acquire_collection(self, collection_id: int = 1) -> SweepCollection:
+        """Acquire the full widened matrix, one inner collection per switch step.
+
+        A partial failure raises instead of returning a short collection: the
+        preprocessor requires every runtime combo to be present, so half a matrix
+        is worse than a dropped frame.
+        """
+        capture_start_ns = time.monotonic_ns()
+        out_steps = self.output_switch.position_count() if self.output_switch is not None else 1
+        in_steps = self.input_switch.position_count() if self.input_switch is not None else 1
+        total_inputs = in_steps * self.inner_input_positions
+        total_outputs = out_steps * self.inner_output_positions
+
+        # Place each trace at its canonical index rather than appending. The GPR stage
+        # rejects a collection whose trace order differs from run.combos, and run.combos
+        # is built output-major (`build_full_combos`) while these loops run switch-major.
+        # Appending happens to agree for an output switch and to disagree for an input one.
+        slots: list[TraceData | None] = [None] * (total_inputs * total_outputs)
+
+        for out_k in range(out_steps):
+            for in_k in range(in_steps):
+                step_start_ns = time.monotonic_ns()
+                if self.output_switch is not None:
+                    self.output_switch.switch_to(out_k)
+                if self.input_switch is not None:
+                    self.input_switch.switch_to(in_k)
+                switched_ns = time.monotonic_ns()
+                # Settle AFTER the last switch change and BEFORE collecting, so the
+                # cycle we anchor on starts with the RF path already stable.
+                if self.settling_ms > 0:
+                    time.sleep(self.settling_ms / 1000.0)
+                settled_ns = time.monotonic_ns()
+
+                sub = self.inner.acquire_collection(collection_id)
+                inner_end_ns = time.monotonic_ns()
+                logger.debug(
+                    "timing: collection %d step out=%d in=%d | gap_prev_collect_to_switch=%s ms, "
+                    "switch=%.3f ms, settle=%.2f ms, inner_collect=%.2f ms",
+                    collection_id,
+                    out_k,
+                    in_k,
+                    (
+                        f"{(step_start_ns - self._last_inner_end_ns) / 1e6:.2f}"
+                        if self._last_inner_end_ns
+                        else "n/a"
+                    ),
+                    (switched_ns - step_start_ns) / 1e6,
+                    (settled_ns - switched_ns) / 1e6,
+                    (inner_end_ns - settled_ns) / 1e6,
+                )
+                self._last_inner_end_ns = inner_end_ns
+                for trace in sub.traces:
+                    input_pos = in_k * self.inner_input_positions + int(trace.combo.input)
+                    output_pos = out_k * self.inner_output_positions + int(trace.combo.output)
+                    slots[output_pos * total_inputs + input_pos] = replace(
+                        trace, combo=ComboKey(input=input_pos, output=output_pos)
+                    )
+
+        if any(trace is None for trace in slots):
+            missing = sum(1 for trace in slots if trace is None)
+            raise RuntimeError(
+                f"Switched matrix collection is incomplete: {missing} of {len(slots)} combos missing"
+            )
+
+        return SweepCollection(
+            collection_id=int(collection_id),
+            monotonic_ns=time.monotonic_ns(),
+            traces=[trace for trace in slots if trace is not None],
+            capture_start_ns=capture_start_ns,
+            capture_end_ns=time.monotonic_ns(),
+        )
+
+def build_physical_switch(
+    model: SwitchModel,
+    physical_positions: int,
+    radar_driver_mode: str,
+) -> SwitchService | None:
+    """Build the driver for a real switch described by a virtual switch section.
+
+    The config section carries the LOGICAL axis size and a forced "mock" mode so
+    the C++ loader accepts it; the real driver needs the PHYSICAL position count
+    and native mode. Mock radar runs keep mock switches so the whole path can be
+    exercised without GPIO.
+    """
+    if physical_positions <= 1:
+        return None
+    driver_mode = "mock" if radar_driver_mode.strip().lower() == "mock" else "native"
+    return SwitchService.from_model(
+        replace(model, positions=physical_positions, driver_mode=driver_mode)
+    )

python_app/models/gui_profile_codec.py

@@ -244,6 +244,12 @@ def gui_profile_from_dict(payload: dict[str, Any]) -> GuiProfileModel:
                 gui.processing.bscan.subtract_mean_ascan,
                 "gui.processing.bscan",
             ),
+            history_window_scans=_optional_int(
+                bscan_object,
+                "history_window_scans",
+                gui.processing.bscan.history_window_scans,
+                "gui.processing.bscan",
+            ),
         ),
         gpr=GuiGprStateModel(
             input_positions=_optional_string(
@@ -579,6 +585,7 @@ def gui_profile_to_dict(model: GuiProfileModel) -> dict[str, Any]:
                 "start_freq_mhz": gui.processing.bscan.start_freq_mhz,
                 "stop_freq_mhz": gui.processing.bscan.stop_freq_mhz,
                 "subtract_mean_ascan": gui.processing.bscan.subtract_mean_ascan,
+                "history_window_scans": gui.processing.bscan.history_window_scans,
             },
             "gpr": {
                 "input_positions": gui.processing.gpr.input_positions,

python_app/models/gui_profile_schema.py

@@ -48,6 +48,10 @@ class GuiBscanStateModel:
     start_freq_mhz: float = 100.0
     stop_freq_mhz: float = 8800.0
     subtract_mean_ascan: bool = False
+    # How many past sweeps the B-scan heatmap renders once acquisition is stopped.
+    # While running the window stays at the C++ replay window (see
+    # `_cpp_bscan_replay_window_for_config`); this only widens the stopped-mode view.
+    history_window_scans: int = 50
 
 
 @dataclass(slots=True)

python_app/models/run_config_codec.py

@@ -219,6 +219,16 @@ def run_config_from_dict(payload: dict[str, Any]) -> RunConfigModel:
         "recovery_attempts",
         model.radar.multi_device.recovery_attempts,
     )
+    model.radar.multi_device.output_switch_positions = _read_int(
+       multi_device_payload,
+       "output_switch_positions",
+       model.radar.multi_device.output_switch_positions,
+    )
+    model.radar.multi_device.input_switch_positions = _read_int(
+           multi_device_payload,
+           "input_switch_positions",
+           model.radar.multi_device.input_switch_positions,
+        )
     model.radar.kamil_adc.project_dir = _read_str(
         kamil_adc_payload, "project_dir", model.radar.kamil_adc.project_dir
     )
@@ -493,6 +503,8 @@ def run_config_to_dict(model: RunConfigModel) -> dict[str, Any]:
                 "slave_serials": list(model.radar.multi_device.slave_serials),
                 "force_external_reference": model.radar.multi_device.force_external_reference,
                 "recovery_attempts": model.radar.multi_device.recovery_attempts,
+                "output_switch_positions": model.radar.multi_device.output_switch_positions,
+                "input_switch_positions": model.radar.multi_device.input_switch_positions
             },
             "kamil_adc": {
                 "project_dir": model.radar.kamil_adc.project_dir,

python_app/models/run_config_schema.py

@@ -40,6 +40,8 @@ class RadarMultiDeviceModel:
     slave_serials: list[str] = field(default_factory=list)
     force_external_reference: bool = True
     recovery_attempts: int = 3
+    output_switch_positions: int = 1   # 1 = свитча нет
+    input_switch_positions: int = 1    # 1 = свитча нет
 
 
 @dataclass(slots=True)
@@ -387,6 +389,24 @@ class RunConfigModel:
         """Return whether this config acquires the full virtual switch matrix per sweep."""
         return self.is_multi_device or self.is_sn9000
 
+    @property
+    def matrix_output_switch_positions(self) -> int:
+        """Physical positions of the real switch on the master stimulus path."""
+        if not self.is_multi_device:
+            return 1
+        return max(1, int(self.radar.multi_device.output_switch_positions))
+
+    @property
+    def matrix_input_switch_positions(self) -> int:
+        """Physical positions of the real switch on the slave receiver path."""
+        if not self.is_multi_device:
+            return 1
+        return max(1, int(self.radar.multi_device.input_switch_positions))
+
+    def build_runtime_combos(self) -> list[ComboModel]:
+        """Build the combo matrix from the effective switch axis sizes."""
+        return self.build_full_combos(self.input_switch.positions, self.output_switch.positions)
+ 
     @property
     def is_kamil_adc(self) -> bool:
         """Return whether this config targets the external Kamil ADC acquisition path."""
@@ -443,22 +463,25 @@ class RunConfigModel:
         if not self.is_matrix_radar:
             return
         self._apply_matrix_virtual_switches()
-        self.combos = self.build_matrix_radar_virtual_combos()
+        self.combos = self.build_runtime_combos()
 
     def _apply_matrix_virtual_switches(self) -> None:
-        """Pin the canonical 2x4 virtual switch matrix used by all matrix-mode radars."""
+        """Pin the virtual switch matrix, widened by any real switch on the path."""
+        out_physical = self.matrix_output_switch_positions
+        in_physical = self.matrix_input_switch_positions
+
         self.output_switch.name = self.output_switch.name or "virtual_output"
         self.output_switch.driver_mode = "mock"
         self.output_switch.driver = self.output_switch.driver or "h7992"
         self.output_switch.radar_port = 1
-        self.output_switch.positions = self.MULTI_DEVICE_OUTPUT_POSITIONS
+        self.output_switch.positions = out_physical * self.MULTI_DEVICE_OUTPUT_POSITIONS
         self.output_switch.default_position = 0
 
         self.input_switch.name = self.input_switch.name or "virtual_input"
         self.input_switch.driver_mode = "mock"
         self.input_switch.driver = self.input_switch.driver or "h7992"
         self.input_switch.radar_port = 2
-        self.input_switch.positions = self.MULTI_DEVICE_INPUT_POSITIONS
+        self.input_switch.positions = in_physical * self.MULTI_DEVICE_INPUT_POSITIONS
         self.input_switch.default_position = 0
 
     def ensure_combos(self) -> None:

python_app/orchestration/process_supervisor.py

@@ -105,7 +105,10 @@ def _read_log_tail(path: Path, max_bytes: int = 16384) -> str:
             data = handle.read()
     except OSError:
         return ""
-    return data.decode("utf-8", errors="replace").strip()
+    # Drop NULs: logs written by an older supervisor can carry a sparse hole from
+    # the pre-O_APPEND truncate bug, and a tail landing in it would otherwise turn
+    # an exit report (or a rolled `.prev`) into megabytes of NUL padding.
+    return data.replace(b"\0", b"").decode("utf-8", errors="replace").strip()
 
 
 class ProcessSupervisor:
@@ -232,8 +235,17 @@ class ProcessSupervisor:
         self._roll_log_to_prev(stdout_path)
         self._roll_log_to_prev(stderr_path)
 
-        stdout_file = open(stdout_path, "wb")
-        stderr_file = open(stderr_path, "wb")
+        # O_APPEND ("ab"), not "wb": the child inherits these fds and keeps its own
+        # file offset. Without O_APPEND, the in-place truncate in
+        # `_roll_log_if_oversized` leaves that offset far past the new end of file,
+        # so the next write lands there and the kernel fills everything before it
+        # with a hole of NUL bytes — the log becomes unreadable and the size cap
+        # stops working entirely. O_APPEND makes the kernel seek to EOF atomically
+        # on every write, so a truncate genuinely restarts the file at offset 0.
+        # `_roll_log_to_prev` above already renamed any previous log away, so not
+        # truncating on open costs nothing.
+        stdout_file = open(stdout_path, "ab")
+        stderr_file = open(stderr_path, "ab")
         try:
             handle = subprocess.Popen(
                 command,
@@ -499,6 +511,11 @@ class ProcessSupervisor:
         The child holds an open fd to this inode, so a rename would not redirect
         its writes. Instead keep one rolled generation via copy-to-`.prev` and
         truncate the live inode in place, freeing the allocated disk blocks.
+
+        This relies on the child's fd being opened with O_APPEND (see `_spawn`):
+        only then does the child resume writing at offset 0 after the truncate.
+        With a plain write fd it would keep writing at its stale offset, punching
+        a multi-hundred-megabyte NUL hole and defeating the cap.
         """
         try:
             if path.stat().st_size <= _LOG_MAX_BYTES:

python_app/scripts/matrix_raw_producer.py

@@ -11,6 +11,7 @@ import threading
 import time
 
 from python_app.hardware_full.matrix_radar_service import MatrixRadarService, create_matrix_radar_service
+from python_app.logging_setup import coerce_level
 from python_app.models.run_config_model import RunConfigModel
 from python_app.orchestration.shm import ShmRingWriter
 from python_app.storage.npz.serialize import RAW_MAGIC, serialize_trace_collection
@@ -95,6 +96,10 @@ def main() -> int:
 
     config = RunConfigModel.load_from_path(args.config)
     config.apply_device_model_constraints()
+    # Honor the configured verbosity so the DEBUG switch/sweep timing trace can be
+    # turned on from the profile instead of requiring a code edit. basicConfig above
+    # only installed the handler; the package logger owns the level.
+    logging.getLogger("python_app").setLevel(coerce_level(config.logging.level))
     if not config.is_matrix_radar:
         raise RuntimeError(
             "matrix_raw_producer requires a matrix-mode radar.model "

python_app/tests/test_bscan_history_window.py

@@ -0,0 +1,140 @@
+"""Configurable B-scan display window.
+
+The B-scan used to be pinned to the C++ replay window (~50 sweeps) by two separate
+mechanisms: the render-side history limit and a monotonically rising
+`_bscan_history_floor_collection_id`. Widening only the first would have changed
+nothing, because the floor kept filtering older collections out for good.
+
+These tests pin the two properties that make the stopped-mode review work: the
+window follows acquisition state, and the floor is recomputed (not ratcheted) so a
+widened window can bring already-discarded frames back into view.
+"""
+
+from __future__ import annotations
+
+import os
+import unittest
+from pathlib import Path
+
+import numpy as np
+
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+from PyQt6.QtWidgets import QApplication  # noqa: E402
+
+from python_app.gui.app_window import AppWindow  # noqa: E402
+from python_app.models.dataset_model import (  # noqa: E402
+    ComboKey,
+    ResultBlock,
+    ResultCollection,
+    ResultPayload,
+)
+
+_app: QApplication | None = None
+_window: AppWindow | None = None
+
+
+def setUpModule() -> None:
+    global _app, _window
+    _app = QApplication.instance() or QApplication([])
+    _window = AppWindow(Path("."))
+
+
+def tearDownModule() -> None:
+    if _window is not None:
+        _window.close()
+
+
+def _bscan_result(collection_id: int) -> ResultCollection:
+    payload = ResultPayload(
+        processing_name="bscan",
+        kind=1,
+        frequency_hz=np.array([0.5, 1.0], dtype=np.float32),
+        trace=np.array([collection_id + 0j, collection_id + 0j], dtype=np.complex64),
+    )
+    block = ResultBlock(combo=ComboKey(input=0, output=0), payloads=[payload])
+    return ResultCollection(collection_id=collection_id, monotonic_ns=collection_id, blocks=[block])
+
+
+class BscanDisplayWindowTest(unittest.TestCase):
+    def setUp(self) -> None:
+        self.w = _window
+        self._original_is_running = self.w._supervisor.is_running
+        self.w._result_history.clear()
+        self.w._bscan_history_floor_collection_id = 0
+
+    def tearDown(self) -> None:
+        self.w._supervisor.is_running = self._original_is_running
+        self.w._result_history.clear()
+        self.w._bscan_history_floor_collection_id = 0
+
+    def _set_running(self, running: bool) -> None:
+        self.w._supervisor.is_running = lambda: running
+
+    def _fill_history(self, count: int, *, id_step: int = 1) -> None:
+        for index in range(count):
+            self.w._result_history.append(_bscan_result(1 + index * id_step))
+
+    def test_running_acquisition_ignores_the_user_window(self) -> None:
+        # A live rebuild runs on every incoming result, so the live path stays pinned
+        # to the replay window no matter what the operator typed for stopped review.
+        self._set_running(True)
+        self.w._bscan_history_window.setValue(300)
+        self.assertEqual(self.w._bscan_display_window_scans(), self.w._bscan_cpp_replay_window)
+
+    def test_stopped_acquisition_uses_the_user_window(self) -> None:
+        self._set_running(False)
+        self.w._bscan_history_window.setValue(300)
+        self.assertEqual(self.w._bscan_display_window_scans(), 300)
+
+    def test_widening_the_window_lowers_the_floor(self) -> None:
+        # The regression this whole change exists for: a run leaves the floor high,
+        # and widening the window afterwards must pull it back down.
+        self._fill_history(300)
+        self._set_running(True)
+        self.w._advance_bscan_floor_to_display_window()
+        raised_floor = self.w._bscan_history_floor_collection_id
+        self.assertEqual(raised_floor, 300 - self.w._bscan_cpp_replay_window)
+
+        self._set_running(False)
+        self.w._bscan_history_window.setValue(300)
+        self.w._advance_bscan_floor_to_display_window()
+        self.assertEqual(self.w._bscan_history_floor_collection_id, 0)
+
+    def test_floor_survives_collection_ids_restarting(self) -> None:
+        # A new C++ run restarts ids from 1. The unconditional recompute must not
+        # leave a stale high floor that hides the whole fresh run.
+        self._fill_history(300)
+        self._set_running(True)
+        self.w._advance_bscan_floor_to_display_window()
+        self.assertGreater(self.w._bscan_history_floor_collection_id, 0)
+
+        self.w._result_history.clear()
+        self._fill_history(5)
+        self.w._advance_bscan_floor_to_display_window()
+        self.assertEqual(self.w._bscan_history_floor_collection_id, 0)
+
+    def test_window_counts_entries_not_collection_ids(self) -> None:
+        # The results ring overwrites unread slots when the producer outruns the GUI
+        # poll loop, so retained collection ids are sparse. A floor of
+        # `latest_id - window` then spans far fewer than `window` entries: this is
+        # exactly the case where asking for 150 sweeps rendered only 87.
+        self._fill_history(300, id_step=3)
+        self._set_running(False)
+        self.w._bscan_history_window.setValue(150)
+        self.w._sync_bscan_history_from_results()
+        self.assertEqual(len(self.w._bscan_history_by_combo[(0, 0)]), 150)
+
+    def test_rebuild_renders_the_full_widened_window(self) -> None:
+        self._fill_history(300)
+        self._set_running(False)
+        self.w._bscan_history_window.setValue(300)
+        self.w._sync_bscan_history_from_results()
+        self.assertEqual(len(self.w._bscan_history_by_combo[(0, 0)]), 300)
+
+        self.w._bscan_history_window.setValue(50)
+        self.w._sync_bscan_history_from_results()
+        self.assertEqual(len(self.w._bscan_history_by_combo[(0, 0)]), 50)
+
+
+if __name__ == "__main__":
+    unittest.main()

python_app/workflows/kamil_adc_neutral_preprocess.py

@@ -1,4 +1,15 @@
-"""Neutral preprocessing-set helpers for Kamil ADC acquisition."""
+"""Neutral preprocessing-set helpers — the "run without calibration" path.
+
+A neutral pair is a calibration set carrying unit S21 (1+0j) and a reference set
+carrying zero S21. The C++ through-calibrator divides measured/calibration and the
+reference is subtracted, so applying both leaves the measured S21 untouched. That
+lets an operator start the pipeline before any real calibration exists, which the
+required-asset check in `_start_run` would otherwise refuse.
+
+Supported models: Kamil ADC (axis from the ADC processing grid) and every
+VNA-style model, including synchronized multi-device LibreVNA (axis from the
+configured linear sweep grid).
+"""
 
 from __future__ import annotations
 
@@ -17,31 +28,65 @@ from python_app.models.run_config_model import ComboModel, RunConfigModel
 logger = logging.getLogger(__name__)
 
 
-def build_kamil_adc_neutral_s21_sets(
+def supports_neutral_preprocess_sets(config: RunConfigModel) -> bool:
+    """Return whether neutral S21 sets can be generated for this radar model.
+
+    Enabled for the Kamil ADC and for synchronized multi-device LibreVNA, the two
+    models whose emitted frequency axis is fully derivable from the config alone.
+    Other models still work through `build_neutral_s21_sets`, but are kept out of the
+    UI shortcut until their axis has been verified against real hardware.
+    """
+    return bool(config.is_kamil_adc or config.is_multi_device)
+
+
+def neutral_frequency_grid_hz(config: RunConfigModel) -> np.ndarray:
+    """Return the exact per-trace frequency axis the configured radar emits.
+
+    Neutral sets must line up sample-for-sample with live sweeps, so the axis comes
+    from the same source the acquisition path uses: the ADC processing grid for Kamil
+    ADC, and the configured linear sweep grid for every VNA-style model (LibreVNA
+    single and multi-device, SN9000, Compact-M). The C++ preprocessor re-checks this
+    axis against the measured one within a tolerance, so a mismatch fails loudly
+    instead of silently corrupting the correction.
+    """
+    if config.is_kamil_adc:
+        # Single source of truth for the axis: the same grid the processor emits.
+        processor = KamilAdcSweepProcessor(
+            KamilAdcProcessingParams.from_kamil_model(config.radar.kamil_adc)
+        )
+        return processor.grid_hz
+
+    points = int(config.radar.sweep.points)
+    if points < 1:
+        raise ValueError("Neutral sets require radar.sweep.points >= 1")
+    if points == 1:
+        return np.array([float(config.radar.sweep.start_hz)], dtype=np.float32)
+    # Mirrors both acquisition paths: the native collector seeds this same linspace
+    # and the mock backend generates it outright.
+    return np.linspace(
+        float(config.radar.sweep.start_hz),
+        float(config.radar.sweep.stop_hz),
+        points,
+        dtype=np.float32,
+    )
+
+
+def build_neutral_s21_sets(
     config: RunConfigModel,
 ) -> tuple[SweepCollection, SweepCollection]:
-    """Build neutral S21 calibration/reference collections for the Kamil ADC radar.
+    """Build neutral S21 calibration/reference collections for the active radar.
 
-    The calibration uses unit S21 (1+0j) and the reference uses zero S21 across
-    every configured combo, so applying them in the preprocessing pipeline leaves
-    the input S21 unchanged. The frequency axis is the exact acquisition grid
-    (``radar.kamil_adc.band``), so neutral sets line up sample-for-sample with
-    live sweeps. Returns the ``(calibration, reference)`` collections.
+    Covers every combo in the effective matrix, so a matrix radar widened by real
+    switches gets a neutral pair for all of its positions and the preprocessor's
+    ``validate_combos()`` is satisfied. Returns ``(calibration, reference)``.
     """
-    if not config.is_kamil_adc:
-        raise ValueError("Neutral Kamil ADC sets require radar.model='kamil_adc'")
-
     combos = list(config.combos)
     if not combos:
-        combos = RunConfigModel.build_full_combos(
-            config.input_switch.positions, config.output_switch.positions
-        )
+        combos = config.build_runtime_combos()
     if not combos:
-        raise ValueError("Kamil ADC neutral sets require at least one switch combo")
+        raise ValueError("Neutral sets require at least one switch combo")
 
-    # Single source of truth for the axis: the same grid the processor emits.
-    processor = KamilAdcSweepProcessor(KamilAdcProcessingParams.from_kamil_model(config.radar.kamil_adc))
-    frequency_hz = processor.grid_hz
+    frequency_hz = neutral_frequency_grid_hz(config)
 
     now_ns = time.monotonic_ns()
     calibration = _neutral_collection(
@@ -57,11 +102,27 @@ def build_kamil_adc_neutral_s21_sets(
         monotonic_ns=now_ns,
     )
     logger.info(
-        "Built neutral Kamil ADC S21 sets: combos=%d points=%d", len(combos), int(frequency_hz.size)
+        "Built neutral S21 sets: model=%s combos=%d points=%d",
+        config.radar.model,
+        len(combos),
+        int(frequency_hz.size),
     )
     return calibration, reference
 
 
+def build_kamil_adc_neutral_s21_sets(
+    config: RunConfigModel,
+) -> tuple[SweepCollection, SweepCollection]:
+    """Build neutral S21 sets, rejecting anything but the Kamil ADC radar.
+
+    Kept as the model-checked entry point for the ADC path; new callers that must
+    work for several radar models should use `build_neutral_s21_sets` instead.
+    """
+    if not config.is_kamil_adc:
+        raise ValueError("Neutral Kamil ADC sets require radar.model='kamil_adc'")
+    return build_neutral_s21_sets(config)
+
+
 def _neutral_collection(
     *,
     combos: list[ComboModel],

python_app/workflows/multi_radar_capture_workflow.py

@@ -81,14 +81,7 @@ class MultiRadarSequentialCaptureSession:
         self._manual_matrix_radar_capture = (
             self._is_matrix_radar and kind in MATRIX_RADAR_MANUAL_CAPTURE_KINDS
         )
-        self._combos = (
-            RunConfigModel.build_matrix_radar_virtual_combos()
-            if self._is_matrix_radar
-            else RunConfigModel.build_full_combos(
-                base_config.input_switch.positions,
-                base_config.output_switch.positions,
-            )
-        )
+        self._combos = base_config.build_runtime_combos()
         if not self._combos:
             raise RuntimeError("No switch combinations available for capture")
 

python_app/workflows/sequential_capture_workflow.py

@@ -64,11 +64,7 @@ class SequentialCaptureSession:
         self._manual_matrix_radar_capture = (
             self._is_matrix_radar and kind in MATRIX_RADAR_MANUAL_CAPTURE_KINDS
         )
-        self._combos = (
-            RunConfigModel.build_matrix_radar_virtual_combos()
-            if self._is_matrix_radar
-            else RunConfigModel.build_full_combos(config.input_switch.positions, config.output_switch.positions)
-        )
+        self._combos = config.build_runtime_combos()
         if not self._combos:
             raise RuntimeError("No switch combinations available for capture")
 

run_config.json

@@ -1,6 +1,6 @@
 {
   "radar": {
-    "model": "librevna",
+    "model": "librevna_multi",
     "serial": "",
     "remote_host": "127.0.0.1",
     "remote_port": 50209,
@@ -8,9 +8,14 @@
     "mock_signal_hz": 5000000.0,
     "visa_library": "",
     "multi_device": {
-      "slave_serials": [],
+      "slave_serials": [
+        "20A1307D5532",
+        "2072306C5532"
+      ],
       "force_external_reference": false,
-      "recovery_attempts": 3
+      "recovery_attempts": 3,
+      "output_switch_positions": 1,
+      "input_switch_positions": 3
     },
     "kamil_adc": {
       "project_dir": "",
@@ -20,7 +25,18 @@
       "env": {},
       "startup_timeout_s": 5.0,
       "sweep_timeout_s": 5.0,
-      "stop_timeout_s": 2.0
+      "stop_timeout_s": 2.0,
+      "phase_calibration": {
+        "phase0_rad": 0.0,
+        "freq0_hz": 2046000000.0,
+        "phase1_rad": 300.0,
+        "freq1_hz": 5612000000.0
+      },
+      "band": {
+        "start_hz": 2100000000.0,
+        "stop_hz": 5500000000.0,
+        "points": 2048
+      }
     },
     "laser_control": {
       "enabled": false,
@@ -75,7 +91,7 @@
       "driver_mode": "mock",
       "driver": "h7992",
       "radar_port": 2,
-      "positions": 4,
+      "positions": 12,
       "default_position": 0,
       "gpio_chip": "/dev/gpiochip0",
       "pin_a": 22,
@@ -92,11 +108,14 @@
     "debounce_ms": 50,
     "action": "capture_tmp_reference"
   },
+  "logging": {
+    "level": "debug"
+  },
   "run": {
     "settling_ms": 0,
     "idle_sleep_ms": 2,
     "continuous": true,
-    "processing_live_config_path": "python_app/runtime/processing_live.json",
+    "processing_live_config_path": "/home/guriy/Documents/radar_system/python_app/runtime/processing_live.json",
     "locator_server": {
       "device_id": 3,
       "protocol_version": 1,
@@ -123,6 +142,38 @@
         "input": 3,
         "output": 0
       },
+      {
+        "input": 4,
+        "output": 0
+      },
+      {
+        "input": 5,
+        "output": 0
+      },
+      {
+        "input": 6,
+        "output": 0
+      },
+      {
+        "input": 7,
+        "output": 0
+      },
+      {
+        "input": 8,
+        "output": 0
+      },
+      {
+        "input": 9,
+        "output": 0
+      },
+      {
+        "input": 10,
+        "output": 0
+      },
+      {
+        "input": 11,
+        "output": 0
+      },
       {
         "input": 0,
         "output": 1
@@ -138,17 +189,49 @@
       {
         "input": 3,
         "output": 1
+      },
+      {
+        "input": 4,
+        "output": 1
+      },
+      {
+        "input": 5,
+        "output": 1
+      },
+      {
+        "input": 6,
+        "output": 1
+      },
+      {
+        "input": 7,
+        "output": 1
+      },
+      {
+        "input": 8,
+        "output": 1
+      },
+      {
+        "input": 9,
+        "output": 1
+      },
+      {
+        "input": 10,
+        "output": 1
+      },
+      {
+        "input": 11,
+        "output": 1
       }
     ]
   },
   "preprocess": {
     "s21": {
       "calibration": {
-        "set_name": "smoke_cal",
+        "set_name": "smoke_cal3",
         "bundle_path": ""
       },
       "reference": {
-        "set_name": "smoke_ref",
+        "set_name": "smoke_cal3",
         "bundle_path": ""
       }
     },
@@ -219,6 +302,54 @@
         "x_m": 0.185,
         "y_m": 0.0,
         "z_m": 0.0
+      },
+      {
+        "input_pos": 4,
+        "x_m": 0.0,
+        "y_m": 0.0,
+        "z_m": 0.0
+      },
+      {
+        "input_pos": 5,
+        "x_m": 0.0,
+        "y_m": 0.0,
+        "z_m": 0.0
+      },
+      {
+        "input_pos": 6,
+        "x_m": 0.0,
+        "y_m": 0.0,
+        "z_m": 0.0
+      },
+      {
+        "input_pos": 7,
+        "x_m": 0.0,
+        "y_m": 0.0,
+        "z_m": 0.0
+      },
+      {
+        "input_pos": 8,
+        "x_m": 0.0,
+        "y_m": 0.0,
+        "z_m": 0.0
+      },
+      {
+        "input_pos": 9,
+        "x_m": 0.0,
+        "y_m": 0.0,
+        "z_m": 0.0
+      },
+      {
+        "input_pos": 10,
+        "x_m": 0.0,
+        "y_m": 0.0,
+        "z_m": 0.0
+      },
+      {
+        "input_pos": 11,
+        "x_m": 0.0,
+        "y_m": 0.0,
+        "z_m": 0.0
       }
     ]
   },
@@ -253,7 +384,7 @@
     "version": 1,
     "switches": {
       "combo_mode": "text",
-      "combos_text": "0:0,1:0,2:0,3:0,0:1,1:1,2:1,3:1",
+      "combos_text": "0:0,1:0,2:0,3:0,4:0,5:0,6:0,7:0,8:0,9:0,10:0,11:0,0:1,1:1,2:1,3:1,4:1,5:1,6:1,7:1,8:1,9:1,10:1,11:1",
       "single_input": "0",
       "single_output": "0"
     },
@@ -262,6 +393,7 @@
       "pass_through": {
         "show_magnitude": true,
         "show_phase": false,
+        "unwrap_phase": false,
         "combo_filter": "",
         "fixed_y_enabled": false,
         "y_min_db": -100.0,
@@ -333,7 +465,8 @@
     "data_actions": {
       "save_count": 10,
       "save_path": "python_app/data/snapshots",
-      "save_name": "snapshot_simulator"
+      "save_name": "snapshot_simulator",
+      "record_count": 100
     },
     "preprocess_dialog": {
       "set_name": "smoke_cal",