feat: implement overlay architecture with IOverlayLayer interface and telemetry overlay

app/telemetry/telemetry_collector.py

@@ -20,8 +20,8 @@ class TelemetrySnapshot:
     fps: float
     frame_time_ms: float          # average inter-frame time in ms
     dropped_frames: int           # cumulative dropped frames detected
-    cpu_percent: float            # overall CPU usage (0–100)
-    memory_mb: float | None       # RSS memory usage in MB (optional)
+    cpu_percent: float            # this process CPU usage (0–100, all cores)
+    memory_mb: float | None       # process private working set in MB
     timestamp: float              # time.perf_counter() when snapshot was taken
 
 
@@ -57,8 +57,9 @@ class TelemetryCollector(QObject):
         self._fps_window: deque[float] = deque()  # timestamps of recent frames
         self._fps_window_size_s: float = 1.0
 
-        # psutil process reference
+        # psutil process reference — call cpu_percent once to initialise the baseline
         self._process = psutil.Process()
+        self._process.cpu_percent()  # first call always returns 0.0; discard it
 
         # periodic snapshot timer
         self._timer = QTimer(self)
@@ -138,15 +139,19 @@ class TelemetryCollector(QObject):
         else:
             avg_frame_time_ms = 0.0
 
-        # CPU
+        # CPU — this process only, cumulative since last call (non-blocking)
         try:
-            cpu = psutil.cpu_percent(interval=None)
+            cpu = self._process.cpu_percent()
         except Exception:
             cpu = 0.0
 
-        # memory
+        # Memory — private working set (Windows) or RSS (macOS/Linux)
+        # This excludes shared DLLs/frameworks and matches Task Manager "Private"
         try:
-            mem_mb = self._process.memory_info().rss / (1024 * 1024)
+            mem_info = self._process.memory_info()
+            # wset = Windows Working Set (private); rss on macOS/Linux
+            mem_bytes = getattr(mem_info, "wset", None) or mem_info.rss
+            mem_mb = mem_bytes / (1024 * 1024)
         except Exception:
             mem_mb = None