Track upstream TypeScript 7 (tsgo) APIs needed for kea-typegen migration

Context

PR #59070 wires @typescript/native-preview (tsgo) as a shadow type-checker alongside tsc, with typescript@6.0.3 retained via pnpm.overrides for every tool that consumes the programmatic Compiler API. The largest such consumer is kea-typegen, which generates the *Type.ts files we depend on for kea logic typing.

This issue tracks the upstream gaps that block migrating kea-typegen (and the rest of our programmatic-API consumers) off typescript@6.

Why this is blocked today

@typescript/native-preview currently ships zero JS-callable code — package.json has no main/types, only a bin entry that subprocesses the native binary. The "Corsa" IPC API exists in microsoft/typescript-go source (_packages/native-preview/src/api/sync/api.ts) but is not bundled to npm.

Even once Corsa ships, kea-typegen's hot path needs APIs that aren't designed yet:

• ts.factory.* — kea-typegen constructs *Type.ts AST nodes
• ts.createPrinter — serializes constructed nodes to text
• checker.typeToTypeNode — converts a resolved Type back into a printable TypeNode
• checker.typeToString, checker.getExportsOfModule — listed as gaps, no open PR

There is also an architectural mismatch: kea-typegen holds live ts.Node references across many checker calls and mutates the AST in-memory. Corsa is IPC: opaque handles, serialize/deserialize per call. No in-process AST graph.

Upstream issues to watch

• microsoft/TypeScript#63771 — Transformer Plugin or Compiler API (open, no timeline)
• microsoft/TypeScript#63800 — API usage patterns for complex editor extensions (Corsa design)
• microsoft/typescript-go#3610 — API: additional Checker methods for transpiler consumers (subset of methods landing incrementally; typeToTypeNode is a listed gap)
• microsoft/typescript-go#3616 — API emit support (open PR, not merged)

Definition of done

• @typescript/native-preview (or a Microsoft-blessed sibling package) ships a JS-importable module with: ts.factory, ts.createPrinter, ts.createSourceFile, Program.getTypeChecker(), TypeChecker.typeToTypeNode, TypeChecker.typeToString, TypeChecker.getExportsOfModule, and the ~40 ts.is* AST predicates kea-typegen relies on.
• kea-typegen's peerDependencies.typescript is bumped to support the 7.x line.
• We drop the pnpm.overrides.typescript = "6.0.3" pin and rely on the catalog entry only.
• Same applies to other API consumers we currently pin: ts-jest, ts-node, ts-json-schema-generator, @parcel/packager-ts, @parcel/transformer-typescript-types.

Realistic timeline

TS 7.1 at the earliest, more likely 7.2+. Microsoft has not committed to a date. No engineering action is feasible until upstream lands the APIs above — this is a watch-list, not a backlog item.

Related

• PR #59070 — adds the tsgo shadow CI step and the coexistence setup this issue depends on.