Scenario: Diamond dependency pattern where multiple paths lead to the same action
input1, input2, input3
↓ ↓ ↓
sum1 sum2 sum3
↓ ↓ ↓
└───→ total ←───┘
↓
result
When an action returns multiple properties (sum1, sum2, sum3), the 'total' action should run ONCE, not three times.
Each property fires event immediately
Batches changes, evaluates once