fix(ts-sdk): Add primaryKey() and index() to SumBuilderImpl and SumColumnBuilder

[Ludv1gL]

Summary

• Codegen unconditionally emits .primaryKey() on all primary key columns, including enum types
• SumBuilderImpl (used for all object-form enums via __t.enum("Name", { ... })) only implemented Defaultable and Nameable — not PrimaryKeyable or Indexable
• This causes a runtime TypeError: SC.primaryKey is not a function whenever an enum type is used as a primary key column

Fix

Add Indexable and PrimaryKeyable interfaces and their methods to:

• SumBuilderImpl (the base class for all enum type builders)
• SumColumnBuilder (the column builder returned by SumBuilderImpl methods)

This matches the existing pattern already present in SimpleSumBuilderImpl and SimpleSumColumnBuilder.

Why SumBuilderImpl and not just SimpleSumBuilderImpl?

Codegen always generates object-form enums:

export const PlatformModuleType = __t.enum("PlatformModuleType", {
  Standard: __t.unit,
  Control: __t.unit,
});

The runtime dispatch in type_builders.ts (line ~3656) routes object-form enums to SumBuilder (backed by SumBuilderImpl), never to SimpleSumBuilder. So SimpleSumBuilderImpl's existing primaryKey()/index() methods are effectively dead code for codegen output.

Test plan

• Verify enum types used as primary keys no longer throw TypeError: SC.primaryKey is not a function
• Verify existing SimpleSumBuilderImpl/SimpleSumColumnBuilder behavior is unchanged (subclass overrides still work)

🤖 Generated with Claude Code

[cloutiertyler]

@gefjon correct me if I'm wrong, but I don't believe we support indexing and filtering on sum types, and to add support we'd have to add support in all languages. Definitely shouldn't have a runtime error, but I think the fix is to disallow primary keys on sum types, at least for now.

[gefjon]

@gefjon correct me if I'm wrong, but I don't believe we support indexing and filtering on sum types, and to add support we'd have to add support in all languages. Definitely shouldn't have a runtime error, but I think the fix is to disallow primary keys on sum types, at least for now.

I believe we allow filtering and primary-key annotations on simple enums, i.e. those where all variants have the unit payload. It's possible I'm misremembering, thought.

[Ludv1gL]

Yeah and I definitely remember this was added to the C++ library back in the day since it was in sdk-test.
And we are using a simple enum pk in rust and now typescript (with this PR) successfully.
Not sure how it's implemented in Unreal and C#.
So question is also, why didn't the sdk-test catch this for Typescript?

[Ludv1gL]

I asked a friend and got this summary, which aligns with my intuition that the Typescript SDK is the odd one out:

Layer	Component	Enum PK	Notes
Core: schema validation	crates/schema	Simple	Direct index: unit-variant enums only
Core: BSATN eq/hash	crates/sats, crates/table	Full	Sum types fully supported
Server bindings: Rust	crates/bindings{,-macro}	Works	No type restriction (except scheduled=u64)
Server bindings: C#	crates/bindings-csharp	Works	Enum byte-tag serialization
Server bindings: C++	crates/bindings-cpp	Works	FilterableValue concept includes enums
Codegen	crates/codegen	Works	Emits .primaryKey() unconditionally
Client SDK: Rust	sdks/rust	Works	Eq+Hash traits, tested
Client SDK: C#	sdks/csharp	Works*	*TODO: exhaustive PK type testing needed
Client SDK: TypeScript	sdks/typescript (=bindings-typescript)	Fixed by PR	SumBuilderImpl was missing PrimaryKeyable
Client SDK: Unreal	sdks/unreal	Works	UENUM uint8, fully tested

[cloutiertyler]

In that case, I'm going to approve this one.