test: add unit tests for heartbeat stale threshold increase

tests/tools/test_heartbeat_stale_thresholds.py

@@ -0,0 +1,35 @@
+"""Tests for delegate heartbeat stale threshold configuration."""
+
+import pytest
+
+
+class TestHeartbeatStaleThresholds:
+    """Verify the heartbeat stale threshold constants are correct."""
+
+    def test_idle_cycles_value(self):
+        """IDLE stale cycles should be 15 (15 * 30s = 450s)."""
+        from tools.delegate_tool import _HEARTBEAT_STALE_CYCLES_IDLE
+        assert _HEARTBEAT_STALE_CYCLES_IDLE == 15
+
+    def test_in_tool_cycles_value(self):
+        """IN_TOOL stale cycles should be 40 (40 * 30s = 1200s)."""
+        from tools.delegate_tool import _HEARTBEAT_STALE_CYCLES_IN_TOOL
+        assert _HEARTBEAT_STALE_CYCLES_IN_TOOL == 40
+
+    def test_idle_timeout_seconds(self):
+        """Effective idle stale timeout: 15 * 30 = 450s (> typical LLM response time)."""
+        from tools.delegate_tool import _HEARTBEAT_STALE_CYCLES_IDLE, _HEARTBEAT_INTERVAL
+        effective = _HEARTBEAT_STALE_CYCLES_IDLE * _HEARTBEAT_INTERVAL
+        assert effective == 450
+        assert effective > 300  # Must be > 5 minutes for slow LLM responses
+
+    def test_in_tool_timeout_seconds(self):
+        """Effective in-tool stale timeout: 40 * 30 = 1200s (= 20 minutes)."""
+        from tools.delegate_tool import _HEARTBEAT_STALE_CYCLES_IN_TOOL, _HEARTBEAT_INTERVAL
+        effective = _HEARTBEAT_STALE_CYCLES_IN_TOOL * _HEARTBEAT_INTERVAL
+        assert effective == 1200
+
+    def test_interval_unchanged(self):
+        """Heartbeat interval should remain 30s."""
+        from tools.delegate_tool import _HEARTBEAT_INTERVAL
+        assert _HEARTBEAT_INTERVAL == 30