Buyer brief · 20 September 2026
Change a live system
Replace what is broken without making users start again.
A live product needs stabilisation, replatforming or replacement. Its undocumented behaviour still matters to users, and stopping the service or losing parity is not an acceptable migration plan.
01 · The commercial route
What can be commissioned
Prices exclude VAT. Prices and durations shown are published starting terms; the written proposal fixes scope and fees.
02 · Tangible output
What leaves with you
- An agreed inventory of critical existing behaviours, data, integrations, failure modes and the change boundary.
- A replacement or recovery path tested against that boundary, with comparison checks for the agreed corpus and a documented difference ledger. A general-purpose reusable harness is S8, separately scoped and priced.
- Cutover criteria, monitoring and a tested rollback route until the new path earns retirement of the old one.
03 · Authority
Who does what
You: Provide access to the running system, knowledgeable operators, source and records where held; decide which behaviour must be preserved and who can authorise cutover.
Zero Drift: Recover the behavioural contract, implement behind it, expose divergence before release and retain the test and recovery machinery for later changes.
04 · Decision gate
What acceptance means
Old and new paths are compared against the agreed recorded corpus. Differences are resolved or explicitly accepted; cutover and rollback are demonstrated. The evidence names what the corpus does not cover.
Agree first: Production access, data protection, maintenance windows, incumbent-supplier dependencies and cutover authority are agreed before live intervention.
Boundary: Zero differences in a measured corpus does not mean every possible behaviour has been tested. The Ember receipt is evidence of one bounded replacement, not a guarantee for another estate.
05 · Check it
Evidence and next step
A decision aid, not a contract or an unqualified claim about a system not yet inspected. The proposal and signed agreement govern scope, responsibility and acceptance.