perry-codegen: `@perry_class_keys_<module>__<ClassName>` symbol-name collisions when the same class name appears twice in one module

[proggeramlug]

What happened

When a single TypeScript module declares two (or more) classes that share a name in different scopes (top-level + inside a function, or inside two different functions), Perry's codegen emits the global @perry_class_keys_<module>__<ClassName> array of property keys once per class — but with the same symbol name. clang then rejects the IR with:

error: redefinition of global '@perry_class_keys_node_modules_effect_src_<module>__<ClassName>'

7 modules in Effect 3.21.2 trigger this:

Module	Colliding class name
effect/src/Schema.ts	Refinement
effect/src/JSONSchema.ts	Refinement
effect/src/Pretty.ts	Refinement
effect/src/internal/fiberRuntime.ts	Class
effect/src/internal/mailbox.ts	Class
effect/src/internal/core.ts	SingleShotGen
effect/src/internal/stm/core.ts	SingleShotGen

What you expected

Perry's class-keys symbol naming should disambiguate same-named classes within a module — e.g. by appending a counter / scope hash, or by including the lexical scope path in the mangled name (<module>__<ScopePath>__<ClassName>). Today it only uses <module>__<ClassName>.

Minimal reproduction

function makeOuter() {
  class Refinement { kind = "outer"; }
  return new Refinement();
}
function makeInner() {
  class Refinement { kind = "inner"; }
  return new Refinement();
}
console.log(makeOuter().kind, makeInner().kind);

perry compile repro.ts -o /tmp/out
# fails with: error: redefinition of global '@perry_class_keys_repro_ts__Refinement'

The same shape applies to two top-level classes that happen to share a name across if (...) { class C {} } branches, but the two-functions form is the cleanest repro.

Likely fix site

Search crates/perry-codegen/src/codegen.rs (or wherever class-keys globals are emitted) for @perry_class_keys_. The mangled name needs a scope discriminant. Same pattern would also affect @perry_class_methods_, @perry_class_field_init_, etc. — worth a sweep across all per-class globals to make sure they all carry the discriminant.

A minimal fix is a per-module BTreeMap<ClassName, usize> counter; second occurrence of Refinement in Schema.ts becomes @perry_class_keys_..._Refinement_2 etc. The discriminant must be deterministic (lexical-order scan), so successive compiles produce the same mangled name and downstream module-init / dispatch references resolve.

Environment

• Perry version: 0.5.424
• Host OS: macOS 26.4 (arm64)
• Target: native
• Effect version: 3.21.2 (where this surfaced)

Discovered as the largest residual cause of post-#314/#315/#316/#317/#318/#319/#320 failures. Tracked under #321.

[proggeramlug]

Tracked under umbrella #321 (Effect framework end-to-end compat).