ADR 0008: @arachnejs/schema — Standard Schema DSL

• Status: Accepted
• Date: 2026-09-28
• Deciders: Arachne core

Context #

README promises “one schema, many outputs” (DB, forms, admin, OpenAPI, search). @arachnejs/config already ships a thin Standard Schema–compatible DSL for boot config (ADR 0004) and must stay free of a @arachnejs/schema dependency.

Decision #

1. @arachnejs/schema owns the rich application schema DSL: string, number, boolean, literal, enum, object, array, optional, nullable, defaulted, union, plus parse / safeParse and Infer<S> helpers.
2. Schemas implement Standard Schema V1 (~standard.validate).
3. Config keeps its own thin c.* DSL for bootstrap; apps migrate domain models to s.* from @arachnejs/schema.
4. Downstream packages (db, forms, table, admin, OpenAPI) consume Standard Schema values — not a proprietary AST — so third-party schemas (zod, valibot, arktype) remain usable where they expose ~standard.

Alternatives considered #

1. Promote config’s c into schema and re-export — couples boot config to the broader framework; rejected.
2. zod as the only public API — rejected; Standard Schema is the contract.

Consequences #

• New packages register schema edges in boundaries.json (already present).
• MCP surface: validate-via-spec tool + README resource (ADR 0007).