Systems / Incident reconstruction
Incident command desk
Follow a transfer through three services. Find the faults and account for every unit.
A 4-unit transfer returned “Done” too early and lost units. Repair the three-service flow, then forecast a fresh 3-unit transfer with a repeated debit.
Reservations reduce availability. Completion means credit reached the destination. A repeated debit must not remove funds twice.
Incident replay
RESERVATION10source available
→JOURNAL10source balance
→DESTINATION0credited balance
Ask for completion: Done · conserved total should be 10; observed 10
Repair the causal chain
Independent forecast
Start again at source 10, destination 0. Reserve 3, apply debit, retry debit, then credit. Predict the final balances under your repaired rules.
Explore the controls, then check your result.
Need a hint?
During an in-flight transfer, source + destination can temporarily drop after the debit. It must return to 10 after credit. A duplicate debit is a separate bug from an early “Done.”