### Context
GraphQL introspection queries (__schema, __type) were going through the
full Yoga server pipeline, which forces a complete workspace schema
build, loading flat metadata maps, building all GraphQL types, wiring
all resolver factories, and calling makeExecutableSchema. This is
expensive, even though introspection only needs the type structure and
zero resolver execution.
A new WorkspaceGraphqlSchemaSDLService extracts the SDL computation that
was previously embedded inside WorkspaceSchemaFactory.
From `direct-execution.service.ts` :
- `buildSchema(sdl)` reconstructs a resolver-free GraphQLSchema from the
SDL
- pure CPU, not cached, not sure it worths it ?
- `execute({ schema, document, variableValues })` from graphql-js,
introspection is answered entirely by the graphql-js runtime from type
metadata, no resolver execution needed
#### Nice to do ?
- Use new cache service for typeDefs ?
### Renaming bonus: `typeDefs` → `sdl`
`typeDefs` is an Apollo/graphql-tools convention. It's the parameter
name in
`makeExecutableSchema({ typeDefs, resolvers })`, not a native GraphQL
spec term.
In proper GraphQL semantics, what this service produces is the **SDL**
(Schema
Definition Language): the official term for the string representation of
a schema.
`printSchema()` produces it, `buildSchema()` consumes it.
##### Why the distinction matters
- **Type definitions** implies partial type declarations (objects,
scalars, enums…)
- **Schema SDL** conveys a *complete* schema document: all types
**plus** the root
operation types (`Query`, `Mutation`) which is exactly what
`printSchema(schema)`
produces
