kodebeat / papers / platform
Proving a rewrite behaves identically, on production traffic
A traffic-mirroring proxy with a structural response differ.
Serves every request from the primary, mirrors it to a shadow deployment and reports whether the shadow behaves identically. Mirroring is the easy half; the product is the differ and its declarative noise suppression, since timestamps, IDs, ordering and float precision appear in every comparison and bury the difference that matters. Every suppression is counted, so it can never be mistaken for agreement.
What is in it
- The problem — what goes unanswered without it, and who notices first.
- Why the obvious alternative falls short — stated plainly, including where it is the better choice.
- How it works — the method, not a feature list.
- Concrete use cases — with console output quoted from the repository, never reconstructed.
- The methodology behind any number it emits — every term shown, so the figure survives a question.
- What it deliberately does not do — the section most papers leave out.
Part of the Platform & SRE theme.
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