refactor: optimize RBF heatmap performance by decoupling grid resolution from viewport size and update UI file handling.

src/pygui/backend/controllers/session_controller.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 import json
 import logging
 import time
+from pathlib import Path
 from typing import Optional
 
 from PySide6.QtCore import Property, QObject, Qt, QTimer, Signal, Slot
@@ -258,8 +259,6 @@ class SessionController(QObject):
     @Slot(str)
     @slot_error_boundary
     def loadFile(self, file_path: str) -> None:
-        from pathlib import Path
-
         from pygui.backend.data.data_records import (
             is_official_csv,
             read_data_records,
@@ -348,8 +347,6 @@ class SessionController(QObject):
     @slot_error_boundary
     def compareFiles(self, file_a: str, file_b: str) -> None:
         """Run DTW comparison between two CSV files and emit result."""
-        from pathlib import Path
-
         from pygui.backend.comparison import compare_runs
         from pygui.backend.data.data_records import is_official_csv, read_data_records, read_official_csv
 
@@ -603,14 +600,6 @@ class SessionController(QObject):
             return average_clusters(edited, getattr(self, "_active_clusters", []))
         return edited
 
-    # TODO P2.4: throttle live-frame UI updates to ~30Hz
-    #   THINKING: every decoded serial frame triggers frameUpdated/stateChanged,
-    #   which repaints WaferMapItem + trend chart; at high stream rates the GUI
-    #   thread saturates on paint, not decode. Buffer the latest frame and flush
-    #   via a 33ms QTimer (latest-wins, no queue growth). Recording must keep
-    #   writing every frame — only the UI emit is throttled, so place the timer
-    #   here rather than in StreamReader. Depends on nothing; verify with P4.3.
-    #   See docs/pending/alpha-release-polish-plan.md §2.4.
     def _emit_current(self) -> None:
         frame = self._player.current()
         if frame is None: