Add Rust EventEmitter shadow producer parity diagnostics

[jununfly]

This was generated by AI during triage.

Parent

Roadmap node 1-6-8-2. Rust shadow/double-read dynamic-dispatch edge migration follow-up in docs/plans/2026-06-27-rust-indexing-debt-to-rust-migration-roadmap.json.

Plan: docs/plans/2026-06-29-rust-event-emitter-shadow-producer-plan.md

What to build

Add the first Rust dynamic-dispatch shadow producer for JS/TS EventEmitter named-handler candidates. Rust should discover bounded shadow candidates and expose them through the existing profile/result payload. TypeScript should compare those candidates against the current TypeScript-written heuristic EventEmitter graph and report parity diagnostics. Rust-produced candidates must remain shadow-only and must not be consumed for graph writes.

Acceptance criteria

• Rust core profile exposes EventEmitter named-handler shadow candidates with candidate count, bounded samples, and protocol-compatible metadata.
• TypeScript finalization diagnostics compare Rust shadow candidates against TypeScript EventEmitter heuristic graph edges and report compared, matched, mismatch, reason, and sample fields.
• Enabling the shadow producer does not change graph node/edge output; TypeScript remains the only production heuristic edge writer.
• Tests cover the Rust producer profile contract, TypeScript parity contract, and no-graph-delta boundary on a bounded EventEmitter fixture.
• Roadmap node 1-6-8-2 is updated with the completed evidence, while Agent Sufficiency A/B remains a later gate because this slice has no behavior change.

Blocked by

None - can start immediately.

[jununfly]

This was generated by AI during triage.

Closing as implemented. Rust core now emits EventEmitter named-handler shadow candidates in the index profile, and TypeScript finalization compares those candidates against the existing TypeScript heuristic EventEmitter graph under dynamicDispatchHeuristicEdgeProtocol.graphParity.eventEmitterShadow. Rust-produced candidates remain shadow-only and are not consumed for graph writes.