From 5601d190cc43bcd280bd092c9ab8b7cff52b973e Mon Sep 17 00:00:00 2001
From: Matvii Sakhnenko <matvii.sakhnenko@vend.com>
Date: Tue, 7 Apr 2026 13:03:57 +0200
Subject: [PATCH] fix: set misfire_grace_time=None for reliable heartbeats

With misfire_grace_time=300, heartbeats were still missed when the bot
was busy for >5 minutes (observed: 8m54s miss). Setting to None
guarantees every job fires exactly once, combined with coalesce=True
to prevent duplicate execution.
---
 src/scheduler/scheduler.py                    |  7 +++-
 .../test_scheduler/test_misfire_config.py     | 37 +++++++++++++++++++
 2 files changed, 43 insertions(+), 1 deletion(-)
 create mode 100644 tests/unit/test_scheduler/test_misfire_config.py

diff --git a/src/scheduler/scheduler.py b/src/scheduler/scheduler.py
index 98d90a55..8cbca1d6 100644
--- a/src/scheduler/scheduler.py
+++ b/src/scheduler/scheduler.py
@@ -32,7 +32,12 @@ def __init__(
         self.event_bus = event_bus
         self.db_manager = db_manager
         self.default_working_directory = default_working_directory
-        self._scheduler = AsyncIOScheduler()
+        self._scheduler = AsyncIOScheduler(
+            job_defaults={
+                "misfire_grace_time": None,  # Always run, no matter how late
+                "coalesce": True,            # Merge multiple missed runs into one
+            }
+        )
 
     async def start(self) -> None:
         """Load persisted jobs and start the scheduler."""
diff --git a/tests/unit/test_scheduler/test_misfire_config.py b/tests/unit/test_scheduler/test_misfire_config.py
new file mode 100644
index 00000000..9f3f5f89
--- /dev/null
+++ b/tests/unit/test_scheduler/test_misfire_config.py
@@ -0,0 +1,37 @@
+"""Tests for scheduler misfire configuration."""
+
+from unittest.mock import MagicMock
+
+import pytest
+
+from src.events.bus import EventBus
+from src.scheduler.scheduler import JobScheduler
+from src.storage.database import DatabaseManager
+
+
+class TestSchedulerMisfireConfig:
+    """Verify APScheduler is configured for resilient job execution."""
+
+    @pytest.fixture
+    def scheduler(self, tmp_path):
+        event_bus = EventBus()
+        db_manager = MagicMock(spec=DatabaseManager)
+        return JobScheduler(
+            event_bus=event_bus,
+            db_manager=db_manager,
+            default_working_directory=tmp_path,
+        )
+
+    def test_misfire_grace_time_is_none(self, scheduler):
+        """misfire_grace_time=None ensures jobs always run, no matter how late."""
+        job_defaults = scheduler._scheduler._job_defaults
+        assert job_defaults.get("misfire_grace_time") is None, (
+            "misfire_grace_time must be None to guarantee late jobs still fire"
+        )
+
+    def test_coalesce_is_enabled(self, scheduler):
+        """coalesce=True merges multiple missed runs into a single execution."""
+        job_defaults = scheduler._scheduler._job_defaults
+        assert job_defaults.get("coalesce") is True, (
+            "coalesce must be True to prevent spam-firing missed runs"
+        )