Add real switch support for multi-device matrix radar

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.

python_app/hardware_full/switched_matrix_radar_service.py

@@ -0,0 +1,130 @@
+"""Matrix radar behind real GPIO switches on the stimulus and/or receiver path."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, 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
+
+    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):
+            if self.output_switch is not None:
+                self.output_switch.switch_to(out_k)
+            for in_k in range(in_steps):
+                if self.input_switch is not None:
+                    self.input_switch.switch_to(in_k)
+                # 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)
+
+                sub = self.inner.acquire_collection(collection_id)
+                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)
+    )