Mongo + SQLite authoring builders: construct namespace IR-class instances to allow narrowing Namespace.kind to required in family validators

[coderabbitai]

Background

PR #552 (TML-2584 S1.A substrate) narrowed Namespace.kind to required at the TypeScript type level across the framework, SQL, and Mongo IR classes. However, the Mongo contract-ts builder (packages/2-mongo-family/2-authoring/contract-ts/src/contract-builder.ts ~L1515) still constructs plain object literals for namespaces:

storageBody = { namespaces: { [UNBOUND_NAMESPACE_ID]: { id, collections } } }

No kind property is present, no class instance is constructed. As a result:

• Making kind required in createMongoNamespaceEnvelopeSchema (and the equivalent SQL path) would surface kind enumerably on those literals, changing the storage-hash input and breaking pnpm fixtures:check.
• On-disk unbound Mongo contracts carry no kind key today.
• The same plain-literal bypass affects the SQLite path (sqlite fixtures likewise omit kind on the namespace literal).

This condition is captured in drive/retro/findings.md (2026-05-20 entry, "plain-literal namespace path bypass").

Required work

• Lift the Mongo authoring builder to construct new MongoStorage(...) / new MongoNamespacePayload(...) instances so that kind is set non-enumerably (matching the class-hierarchy convention) and the storage hash input is unchanged.
• Apply the equivalent lift to the SQLite authoring builder.
• Once both builders use class instances, tighten the family validators to require kind: 'string' (removing the ?) in createMongoNamespaceEnvelopeSchema and its SQL counterpart.
• Verify pnpm fixtures:check passes with zero drift after the change.

Relationship to other follow-ups

This is a sibling cleanup to TML-2634 (slot renames) and TML-2636 (emitter cleanups). It should be sequenced after the builder migration work is scoped.

References

• PR TML-2584: target packs contribute entity descriptors with hydration and validation #552 (TML-2584 S1.A) — substrate slice where this was identified and deferred
• Comment: TML-2584: target packs contribute entity descriptors with hydration and validation #552 (comment)
• Requester: @wmadden