web UI added and refactoring done

python_app/orchestration/restart_policy.py

@@ -0,0 +1,47 @@
+"""Crash auto-restart back-off policy (pure, GUI-independent)."""
+
+from __future__ import annotations
+
+import math
+from dataclasses import dataclass
+
+
+@dataclass(frozen=True, slots=True)
+class RestartPolicy:
+    """Decide when to relaunch a crashed pipeline — retry forever with capped back-off.
+
+    This is an unattended appliance, so the pipeline never permanently gives up. The
+    wait between restart attempts grows with the number of consecutive failures (so a
+    persistently broken pipeline is not hammered) but is capped at ``max_interval_s``,
+    and the failure streak resets to zero once genuine data flows again. A burst of
+    crash signals within the current back-off window collapses to a single restart.
+    """
+
+    min_interval_s: float = 3.0
+    max_interval_s: float = 60.0
+    backoff_factor: float = 2.0
+
+    def backoff_for(self, consecutive_failures: int) -> float:
+        """Return the seconds to wait before the next restart for this failure streak.
+
+        ``consecutive_failures`` is the number of restarts already attempted without a
+        recovery: 0 → ``min_interval_s``, then each additional failure multiplies the
+        wait by ``backoff_factor``, capped at ``max_interval_s``.
+        """
+        if consecutive_failures <= 0:
+            return self.min_interval_s
+        # Beyond this many doublings the wait is always capped; clamp the exponent so a
+        # long streak cannot overflow ``factor ** n``.
+        max_exponent = max(1, math.ceil(math.log(self.max_interval_s / self.min_interval_s, self.backoff_factor)))
+        exponent = min(int(consecutive_failures), max_exponent)
+        return min(self.min_interval_s * (self.backoff_factor ** exponent), self.max_interval_s)
+
+    def should_restart_now(
+        self,
+        *,
+        now_s: float,
+        last_restart_s: float,
+        consecutive_failures: int,
+    ) -> bool:
+        """Return whether enough back-off has elapsed since the last restart to retry."""
+        return now_s - last_restart_s >= self.backoff_for(consecutive_failures)