Replay Tabs:

- Add stability detection and threshold classification features with corresponding tests

src/pygui/backend/stability_detector.py

@@ -0,0 +1,34 @@
+"""Detect process state (Idle, Ramp, Set) from the running average temp"""
+from __future__ import annotations
+from typing import Optional
+
+STATE_IDLE = "idle"
+STATE_RAMP = "ramp"
+STATE_SET = "set"
+
+
+class StabilityDetector: 
+    def __init__(self, idle_below: float = 50.0, tolerance: float = 1.0, 
+                 settle_seconds: float = 10.0) -> None:
+        self._idle_below = idle_below
+        self._tolerance = tolerance
+        self._settle_seconds = settle_seconds
+        self._near_since: Optional[float] = None    # When avg entered the +- tolerance band
+        
+        
+    def reset(self) -> None:
+        self._near_since = None
+        
+    def update(self, avg: float, time: float, set_point: float) ->str:
+        if avg < self._idle_below:
+            self._near_since = None
+            return STATE_IDLE
+        if abs(avg - set_point) <= self._tolerance:
+            if self._near_since is None:
+                self._near_since = time 
+            if time - self._near_since >= self._settle_seconds:
+                return STATE_SET
+            return STATE_RAMP
+        self._near_since = None
+        return STATE_RAMP
+