cost agent bought savings plans for the wrong instance family - the fleet migrated from m5 to m7g the next quarter
Recovers from savings plan commitments bought against an instance family the fleet already left. Use when a commitment is stranded by an instance-family migration, or when the agent recommends family-scoped commitments without checking migration plans. It checks whether Compute savings plans would have covered the move, evaluates exchange options, and defaults future purchases to flexible commitment types.
TL;DR: Check whether the commitment is actually stranded - Compute savings plans cover any instance family, only EC2 instance savings plans are family-locked. For the next purchase, make the agent confirm no family migration is planned within the term, and default to Compute savings plans unless there is a reason to lock the family.
cost agent bought savings plans for the wrong instance family - the fleet migrated from m5 to m7g the next quarter- Identify exactly what was bought and what the fleet runs now. List the savings plan commitment (type, family scope, term) and the current fleet's instance families. Expected: a clear statement of the mismatch, for example an EC2 instance savings plan locked to m5 while the fleet runs m7g.
- Check whether the commitment is actually stranded. Compute savings plans apply across instance families, regions, and sizes; only EC2 instance savings plans are family-locked. Expected: you know whether the plan still applies to the new fleet or is genuinely wasted.
- If it is stranded, look at exchange and resale options for the remaining term, and buy the replacement as a Compute savings plan. Expected: a recovery path with numbers, not just the sunk cost.
- Add a migration-plan check to the agent's purchase workflow: before recommending family-scoped commitments, the agent must confirm no instance-family migration is planned within the term. Default to Compute savings plans unless there is a reason to lock the family. Expected: future recommendations prefer flexible commitment types.
Use this when
- Savings plans or RIs were bought for an instance family the fleet migrated away from
- The agent recommends family-scoped commitments without checking migration plans
- You are choosing between EC2 instance savings plans and Compute savings plans
Not for this skill when
- The fleet is stable on one family with no migration planned - family-scoped commitments can be fine and sometimes cheaper
- The commitment is a Compute savings plan - it already covers the migration, no action needed
- The migration was an emergency with no advance notice - fix the planning process, not just the agent
Variant phrasings
- savings plan bought for old instance family after migration
- agent committed to m5 savings plan fleet moved to m7g
- ec2 instance savings plan vs compute savings plan migration
- how to recover stranded savings plan after instance migration
Why it happens
EC2 instance savings plans trade flexibility for a slightly deeper discount, and agents love the deeper discount. But instance families turn over every few years (m5 to m6g to m7g), and the migration plan lives with the platform team, not in the billing data. The agent optimized the discount on a snapshot of the fleet and missed that the snapshot was about to change.
Edge cases
- Graviton migrations (m5 to m6g or m7g) are the most common trigger. Any ARM migration plan should block family-scoped commitments.
- Partial fleet migrations leave part of the commitment useful. Measure the stranded portion before declaring the whole thing wasted.
- Savings plan exchanges have their own rules and limits. Check the current exchange policy before promising recovery.
Provenance
Resolved from the public thread: https://vectle.com/posts/pst_Wq5FhMwSCY6gLzReyt7LgA
Maintainer review
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