Components
Branch on domain errors only — exhaustively, or it fails to compile.
The migration path for the tRPC app that grew up
One Result.
One error union.
Server to screen.
Every way an operation can fail is a typed, wire-safe value in its own closed union — and responsibility for each failure is assigned to exactly one place in the component tree.
// the honest base: the complete union
const query = useResultQuery(client.doc.byId, { id })
// DocNotFound | Unauthorized | ServerInternal | Offline |
// NetworkFailure | Timeout | HttpFailure |
// ProtocolViolation | DecodeFailure | Stale
// under the onion: each shell subtracted what it owns
const query = AuthShell.useQuery(client.doc.byId, { id })
// DocNotFound — and a missing case fails to compileFailure ownership, end to end
Every tag has exactly one owner.
Shells
Claim transport blips, auth expiry, and defects at the tree position that owns them.
Entities
Mutations return who changed; every cached view patches in place. Zero refetches.
Deploys
Contract digests detect stale clients; the reload is the fix, not a mystery incident.
Why result-rpc
tRPC ergonomics. Effect-grade errors.
A cache that understands identity.
Closed unions
Errors are values with owners
Every failure a call can produce is a typed, wire-safe tag in that operation’s own closed union — domain, transport, protocol, and staleness in one place.
Error boundaries for values
Shells subtract what they own
Providers claim failure classes ambiently — pause and resume, or escalate to the real error boundary — and remove those tags from the unions components see.
The identity graph
Update by model + id
defineModel gives values identity. Change an avatar and the header, bylines, and member rows patch in place — automatic invalidation and updates, no normalized store.
Coming from tRPC?