refactor(ipc-codegen): keep the generator to erasable TypeScript

[charlielye]

Problem

ipc-codegen/src/generate.ts says:

* Zero npm dependencies — runs with Node.js 22+ via --experimental-strip-types.

It could not. Three parameter properties made Node reject the module at load:

$ node --experimental-strip-types ipc-codegen/src/generate.ts --lang rust ...
SyntaxError [ERR_UNSUPPORTED_TYPESCRIPT_SYNTAX]: TypeScript parameter property is not supported in strip-only mode

generate.ts imports typescript_package_codegen.ts unconditionally, so this broke every --lang, not just ts.

Nothing noticed because all eleven call sites also pass --experimental-transform-types, which compiles parameter properties. The documented invocation was never exercised: the only test that runs strip-only is schema_visitor.test.ts, whose sole local import is schema_visitor.ts — it never reaches generate.ts.

Change

Expanded the three into an explicit field plus an assignment in the constructor body — what the transform emitted anyway:

-  constructor(private opts: CppCodegenOptions) {}
+  private opts: CppCodegenOptions;
+
+  constructor(opts: CppCodegenOptions) {
+    this.opts = opts;
+  }

That makes the source erasable, so --experimental-transform-types comes off all eleven call sites (3 CMakeLists, barretenberg/ts/bootstrap.sh, wsdb/bootstrap.sh, 5 echo_example bootstraps, the README). The generator now runs under the type stripping Node 23.6+ does by default.

--experimental-strip-types is kept: it is a no-op on the pinned Node (.nvmrc is v24.15.0) but is still required by the Node 22 the header mentions.

A fourth parameter property at typescript_package_codegen.ts:332 is inside a template literal — emitted code, not source — so it is untouched.

Verification

• Generated output is byte-identical for all four languages, diffed against the previous invocation (--experimental-strip-types --experimental-transform-types) over bb_schema.json. This is a no-op for consumers.
• All four --lang values generate with the transform flag gone.
• ipc-codegen/test/schema_visitor.test.ts passes; echo_example/rust/bootstrap.sh (a real modified call site) generates fine.
• Probed which constructs strip-only actually rejects, so the constraint is stated from measurement rather than memory: parameter properties, enum, const enum, and namespace are rejected; interfaces, type aliases, annotations, generics and import type are fine.

Guard

The failure mode is invisible while any caller passes the transform flag, so the property needs a test. ipc-codegen/scripts/strip_only_test.sh generates one of each --lang strip-only and is wired into test_cmds. Red/green checked — reintroducing a parameter property fails it:

SyntaxError [ERR_UNSUPPORTED_TYPESCRIPT_SYNTAX]: TypeScript parameter property is not supported in strip-only mode
exit=1

The stronger guard would be erasableSyntaxOnly in a tsconfig, which fails at typecheck rather than at load. Not done here: ipc-codegen has no tsconfig.json or package.json (the "zero npm dependencies" claim is literal), and the repo pins TypeScript ^5.3.3 while that flag landed in 5.8.

🤖 Generated with Claude Code

https://claude.ai/code/session_016einpgfthfjLYGwCB3iQqD