Add global time window control to Plot tab (1–24 h)

A spinbox above the plot grid sets the visible x range for all 8 plots.
Data outside the window is excluded from each redraw; x axis is fixed to
[now - window, now]. Setting is persisted in plot_settings.json.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

gui_client.py

@@ -15,6 +15,7 @@ import json
 import socket
 import sys
 import threading
+import time
 from collections import deque
 from datetime import datetime
 from pathlib import Path
@@ -348,6 +349,22 @@ class PlotTab(QWidget):
         main_layout.setContentsMargins(4, 4, 4, 4)
         main_layout.setSpacing(4)
 
+        # ── toolbar ───────────────────────────────────────────────────────────
+        tb = QWidget()
+        tb.setMaximumHeight(32)
+        tb_row = QHBoxLayout(tb)
+        tb_row.setContentsMargins(0, 0, 0, 0)
+        tb_row.setSpacing(6)
+        tb_row.addWidget(QLabel("Time window:"))
+        self._tw_spin = QSpinBox()
+        self._tw_spin.setRange(1, 24)
+        self._tw_spin.setSuffix(" h")
+        self._tw_spin.setFixedWidth(72)
+        self._tw_spin.valueChanged.connect(self._on_time_window_changed)
+        tb_row.addWidget(self._tw_spin)
+        tb_row.addStretch()
+        main_layout.addWidget(tb)
+
         # ── data ──────────────────────────────────────────────────────────────
         self._traces:       list[list[str]] = [[] for _ in range(self.NUM_PLOTS)]
         self._saved_traces: list[list[str]] = self._load_settings()
@@ -540,25 +557,37 @@ class PlotTab(QWidget):
     def _save_settings(self):
         try:
             _SETTINGS_PATH.parent.mkdir(parents=True, exist_ok=True)
-            _SETTINGS_PATH.write_text(
-                json.dumps({"traces": [list(t) for t in self._traces]}, indent=2)
-            )
+            _SETTINGS_PATH.write_text(json.dumps({
+                "traces":      [list(t) for t in self._traces],
+                "time_window": self._tw_spin.value(),
+            }, indent=2))
         except OSError:
             pass
 
     def _load_settings(self) -> list[list[str]]:
         try:
-            data   = json.loads(_SETTINGS_PATH.read_text())
-            saved  = data.get("traces", [])
+            data  = json.loads(_SETTINGS_PATH.read_text())
+            saved = data.get("traces", [])
             while len(saved) < self.NUM_PLOTS:
                 saved.append([])
+            tw = int(data.get("time_window", 1))
+            self._tw_spin.blockSignals(True)
+            self._tw_spin.setValue(max(1, min(24, tw)))
+            self._tw_spin.blockSignals(False)
             return [list(t) for t in saved[: self.NUM_PLOTS]]
-        except (OSError, json.JSONDecodeError, KeyError):
+        except (OSError, json.JSONDecodeError, KeyError, AttributeError):
             return [[] for _ in range(self.NUM_PLOTS)]
 
     # ── drawing ───────────────────────────────────────────────────────────────
 
+    def _on_time_window_changed(self):
+        self._save_settings()
+        self._redraw()
+
     def _redraw(self):
+        now    = time.time()
+        cutoff = now - self._tw_spin.value() * 3600
+
         for i, pw in enumerate(self._plot_widgets):
             pi = pw.getPlotItem()
             pi.clear()
@@ -569,7 +598,7 @@ class PlotTab(QWidget):
             for j, key in enumerate(self._traces[i]):
                 if key not in self._series:
                     continue
-                series = self._series[key]
+                series = [(t, v) for t, v in self._series[key] if t >= cutoff]
                 if not series:
                     continue
                 times, values = zip(*series)
@@ -580,6 +609,8 @@ class PlotTab(QWidget):
                     name=label,
                 )
 
+            pw.setXRange(cutoff, now, padding=0.02)
+
     # ── cursor tracing ────────────────────────────────────────────────────────
 
     def _on_mouse_move(self, evt, plot_idx: int):