Close out ESM named binding fallback diagnostics map

[jununfly]

This was generated by AI during triage.

Parent

• Plan: docs/plans/2026-06-21-rust-hybrid-esm-named-binding-fallback-diagnostics-map.md
• Resolver migration tracker: Plan: Rust-hybrid resolver migration decision #296
• Architecture/performance PRD tracker: PRD: Rust-hybrid architecture and performance optimization #295
• Optimization tracker: Post-PRD optimization tracker for Rust indexing performance #165

What to build

Write the closeout decision for the ESM named binding fallback diagnostics map and update the relevant trackers. The decision must identify the dominant fallback reasons, distinguish expected boundaries from implementation candidates, and choose the next slice or state no-go.

This closeout should not introduce resolver behavior changes or turn diagnostics into a public API promise.

Acceptance criteria

• A closeout decision artifact is written under docs/benchmarks/.
• The decision references the plan and the evidence artifacts from Run ESM named binding fallback diagnostics map evidence #365.
• The decision lists top fallback reasons and their interpretation.
• The decision chooses the next implementation candidate or records no-go.
• Trackers PRD: Rust-hybrid architecture and performance optimization #295, Plan: Rust-hybrid resolver migration decision #296, and Post-PRD optimization tracker for Rust indexing performance #165 are updated with concise comments.

Blocked by

• Run ESM named binding fallback diagnostics map evidence #365

[jununfly]

This was generated by AI during triage.

Closing with closeout decision recorded in docs/benchmarks/2026-06-21-esm-named-binding-fallback-diagnostics-map-closeout-decision.md. The selected next candidate is direct export candidate gap burndown; package/default/namespace work is explicitly not recommended as the immediate next slice from this evidence.