Rebuild only when the evidence supports the disruption.
A system that is old, undocumented or written by someone else may still be worth keeping. Compare stabilization, replacement of a bounded part, bought software and a rebuild against the business need and the cost of changing over.
01 / What should drive the decision.
| Evidence | Implication to investigate |
|---|---|
| The system supports a valuable workflow but fails in a few identifiable places | A stabilization change may protect the value sooner. |
| A component cannot be supported or safely changed | Replace the component and verify the surrounding dependencies. |
| A bought product now meets the business need | Compare migration, integration, training and ongoing operation. |
| The existing structure cannot meet the necessary behavior at an acceptable cost | A bounded rebuild may be justified. |
| The process or system no longer contributes enough value | Retire it after checking data and downstream dependencies. |
02 / Resolve the unknowns before comparing quotes.
- Who controls code, cloud, data and third-party accounts?
- Can the system be deployed and restored?
- Which behaviors does the business need to preserve?
- What would migration interrupt, and how long must both systems run?
- Who will accept the result and operate it afterward?
An unknown is a cost and risk to investigate. A rewrite quote that assumes clean data, complete access and no business interruptions may look attractive because it omits migration and operating costs.
03 / Prove the next decision in a bounded part.
After the review and build decision, choose a change small enough to test and recover. Use written acceptance criteria and a rollback plan. Carry the operating knowledge forward so the next decision starts from evidence.
See the takeover service, compare build and buy and prepare the handover.
Editorial review: Ego Eimi · Updated September 6, 2026 · About the team
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Tell us which system matters, what has changed and who controls it. We will define a reviewable next step. Read Foundation and the commitments and evidence.