Aglet

How to investigate a checkout inventory conflict

Investigate one inventory conflict across the availability read, cart, reservation, payment gate, and order write. Compare version or timestamp information at each boundary. Possible causes include stale reads, competing reservations, release timing, or an out-of-order update; only the correlated records can narrow the explanation.

Build a useful investigation brief

  1. Rebuild the state sequence

    Place availability read, cart update, reservation attempt, inventory mutation, payment gate, and order creation on one timeline. Compare the requested quantity with each record. Note where a version changes without the next stage seeing it.

  2. Test competing actions

    Run controlled parallel attempts for the same item and quantity, then repeat with different quantities and variants. Compare which attempt receives a reservation, which is rejected, and whether a failed attempt releases its state. Preserve timing and fixture identifiers.

  3. Follow rollback paths

    Inspect cancellation, payment failure, timeout, and abandoned checkout handling. Verify reservations are released or retained according to an observed rule. If the order and inventory records disagree after failure, document the reconciliation gap rather than assuming a successful rollback.

What to carry forward

The investigation is ready when another engineer can replay the inventory race and identify the first inconsistent version, reservation, or order field. Deliver the timeline, competing attempts, rollback evidence, and unresolved concurrency hypotheses before choosing a fix.

Keep the decision with the work.

Use a Work Item in Aglet to record the problem, the evidence you have, and the next decision. Add an owner and priority, then keep updates in the discussion so the next person can follow the reasoning.

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