feat: implement phase1 state machine, composite exits, and kill-switch orchestration (#275)

tests/test_strategy_state_machine.py

@@ -0,0 +1,30 @@
+from src.strategy.position_state_machine import (
+    PositionState,
+    StateTransitionInput,
+    promote_state,
+)
+
+
+def test_gap_jump_promotes_to_armed_directly() -> None:
+    state = promote_state(
+        PositionState.HOLDING,
+        StateTransitionInput(
+            unrealized_pnl_pct=4.0,
+            be_arm_pct=1.2,
+            arm_pct=2.8,
+        ),
+    )
+    assert state == PositionState.ARMED
+
+
+def test_exited_has_priority_over_promotion() -> None:
+    state = promote_state(
+        PositionState.HOLDING,
+        StateTransitionInput(
+            unrealized_pnl_pct=5.0,
+            be_arm_pct=1.2,
+            arm_pct=2.8,
+            hard_stop_hit=True,
+        ),
+    )
+    assert state == PositionState.EXITED