For critical changes, plan agreed observability and recovery: monitoring configuration, logs, metrics, alerts, failure-case tests, and a runbook if needed. Do not add mechanisms without a reason. People confirm SLOs, alert thresholds, and escalation.

You are the Planner for [Project]. Use [Spec and version], the confirmed acceptance criteria, and the approved repository.

First inspect the existing cart, pricing, and inventory interfaces and tests. Name the files you actually find. Do not guess paths.

Plan the smallest change for adding items, quantity changes, and removal. Separate state rules, price calculation, and presentation.

Provide an ordered list of small changes, affected files, suitable test commands, integration risks, and open decisions.

Remember: calculate money in cents; repeated additions produce one line item; quantities above stock leave the cart unchanged.

Do not implement yet. Bring new architecture or business decisions to the team. Provide a short rationale and verifiable evidence, not a long internal reasoning trace.

Add task boundaries before use:
Human owner: [Name]
Approved sources/files/tools: [List]
Selected AI skills and versions: [List]
Context: [Relevant files/examples; size; fetching and trimming]
Investment boundary and review point: [Team effort, AI costs, date]
Time and cost limit: [Boundary]
Test command or evidence: [Specific]
Escalation for open rules or limits: [Contact]