Summary

Closes #2139

Native's CHA dispatch (resolve_cha_dispatch, added by #2236) only ran as tier 3.7 inside resolve_call_targets' mutually-exclusive resolution cascade — reached only when every earlier tier found nothing. WASM's equivalent (emitChaCallEdgesForCall) runs unconditionally as an additive Step 6, independent of what the rest of the cascade already resolved.

This mattered because an earlier tier (import-aware resolution, which matches call.name regardless of receiver) can return a target and short-circuit the whole cascade before CHA ever runs. Concretely: src/shared/hierarchy.ts's resolveViaRepo calls repo.getClassHierarchy() where repo: Repository has three implementers (InMemoryRepository/NativeRepository/SqliteRepository) — but getClassHierarchy is also an importable free function, so tier 1 matched on the name alone and returned before CHA could expand the interface dispatch. Native produced zero edges to any implementer; WASM produced three.

Fix

emit_cha_dispatch_edges runs unconditionally from process_file's per-call loop, alongside emit_call_edges/emit_receiver_edge, mirroring emitChaCallEdgesForCall exactly (same type_map lookup, same resolve_cha_dispatch BFS, same CHA_TYPED_DISPATCH_CONFIDENCE, same 'cha' technique tag). this/self/super dispatch is excluded — that stays with runPostNativeThisDispatch.

Verification

• Rebuilt the native addon and ran codegraph build --engine native against this repo's own source: resolveViaRepo now correctly emits CHA edges to InMemoryRepository.getClassHierarchy and NativeRepository.getClassHierarchy (previously zero implementer edges at all).
• SqliteRepository still doesn't get its edge — it's only ever instantiated via an object-literal property value, which native's RTA evidence doesn't currently track (a separate, narrower gap — filed as follow-up: native CHA/RTA instantiation evidence lacks new_expressions, missing object-literal/bare-assignment instantiated implementers (#2139 follow-up) #2346).
• scripts/parity-compare.mjs --langs javascript,typescript,tsx,pts-javascript — byte-identical node/edge counts on both engines.
• Updated cha_typed_dispatch_fallback_does_not_override_successful_proximity_lookup, which encoded the old (never actually WASM-parity-correct) mutually-exclusive assumption — verified empirically that real WASM output has both the direct proximity hit and the CHA-expanded edge coexisting for the same call site.

Test plan

• New fixture (tests/fixtures/cha-dispatch/{IGreeter,FormalGreeter,CasualGreeter,greet,NameCollisionDispatcher}.ts) reproducing the exact short-circuit shape: an interface-typed receiver dispatch where the file also imports a free function sharing the interface method's name. New describe.each(['wasm','native']) cases in tests/integration/phase-8.5-cha-dispatch.test.ts confirm both engines now emit both CHA-expanded edges additively, alongside the pre-existing free-function edge.
• Full cargo test --lib passes (820 tests).
• Full npm test suite passes (4621 tests, 288 files).
• npx tsc --noEmit and npm run lint clean.

Filed #2346 (RTA new_expressions gap), #2347 (possible WASM cross-fixture false positives — unrelated direction, needs its own investigation per the issue's own notes), and #2348 (odd zero-line edges) for the issue's other, lower-priority observations not addressed here.