Expand description
The substrate open/construction error surface — the wave-6 scaffold’s pin (ADR-024 §1’s fallible-constructor posture: construction fails loudly and a half-migrated store refuses service rather than degrading silently).
Not one of the core’s two backend-family error types
(RegistryError,
StorageError) and deliberately without any
conversion into them: the backend-family variant sets are closed over
the failures their families produce, with no catch-all (backend.md
§RegistryError) — a blanket From here would funnel engine-specific
construction failures into that closed set and break the claim. The
substrate’s constructors are assembly-time calls that happen before
any backend-trait call exists, so their failures never cross the trait
seam’s Result<_, RegistryError>/Result<_, StorageError> surface
and never reach the wire; a dedicated type is the honest shape. The
migration step’s failure context (ADR-024 §1’s loud construction-time
run) rides OpenError::Migration, which the migrations task
consumes.
Message-only by the family posture: engine source types
(rusqlite::Error, tokio_postgres::Error) are not stable public
surface, so their text is carried in the payload — the same rule the
core’s RegistryError::Io/StorageError::Io pins.
Enums§
- Open
Error - The error the substrate’s constructors fail with (open, reactivity start, adapter construction, construction-time migrations).