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uptide

0005: No database, no service in milestone 1

Status: accepted (2026-09-27)

Context

Section titled “Context”

A shared store of surfaces and diffs is an obvious product feature: most users will ask about the same popular package pairs. It is also a server, an account system and an operational burden, none of which help measure whether the diff engine is precise.

Decision

Section titled “Decision”

Everything is local files. Tarballs and surfaces live in ~/.cache/uptide/ behind the PackageFetcher and SurfaceCache interfaces. The npm registry is the only network dependency. There is no telemetry and no user code anywhere in this milestone.

Consequences

Section titled “Consequences”
  • The engine is a pure function of two surfaces; tests stub the two interfaces with in-memory versions and the whole suite runs offline in about a second.
  • A remote cache can be added as another SurfaceCache implementation without touching diffSurfaces, the adapter or the CLI.
  • Real-pair snapshot tests are gated behind UPTIDE_NETWORK=1 and store a digest, not the full Change[], because the full form runs to 19MB for eight pairs.