perf(lambda-rs): Optimize event dispatch

[vmarcella]

Summary

Optimizes ApplicationRuntime event dispatch by precomputing per-category
listener buckets so each event is delivered only to interested components
instead of scanning the full component stack. This reduces dispatch from
O(C) per event to O(k) per event after a one-time O(C) startup index
build, where C is total components and k is listeners for the event
category.

Related Issues

Changes

• Added per-category event listener indexing in
  crates/lambda-rs/src/runtimes/application.rs
• Updated dispatch to iterate only listeners for the current event category
• Added unit tests for bucket mapping, empty-mask rejection, and listener index
  construction

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• Feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (updates to docs, specs, tutorials, or comments)
• Refactor (code change that neither fixes a bug nor adds a feature)
• Performance (change that improves performance)
• Test (adding or updating tests)
• Build/CI (changes to build process or CI configuration)

Affected Crates

• lambda-rs
• lambda-rs-platform
• lambda-rs-args
• lambda-rs-logging
• Other:

Checklist

• Code follows the repository style guidelines (cargo +nightly fmt --all)
• Code passes clippy (cargo clippy --workspace --all-targets -- -D warnings)
• Tests pass (cargo test --workspace)
• New code includes appropriate documentation
• Public API changes are documented
• Breaking changes are noted in this PR description

Testing

Commands run:

cargo test -p lambda-rs runtimes::application

Manual verification steps (if applicable):

Screenshots/Recordings

N/A

Platform Testing

• macOS
• Windows
• Linux

Additional Notes

[github-actions]

✅ Coverage Report

📊 View Full HTML Report (download artifact)

Overall Coverage

Metric	Value
Total Line Coverage	76.91%
Lines Covered	12762 / 16593

Changed Files in This PR

File	Coverage	Lines
crates/lambda-rs/src/runtimes/application.rs	35.86%	199/555

PR Files Coverage: 35.85% (199/555 lines)

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Generated by cargo-llvm-cov · Latest main coverage

_{Last updated: 2026-03-12 20:10:50 UTC · Commit: 2c38017}

[Copilot]

Pull request overview

Optimizes ApplicationRuntime event dispatch by introducing a precomputed per-category listener index, reducing per-event iteration to only components interested in the event’s category.

Changes:

• Added event_listener_bucket and build_event_listener_index helpers to map event categories to listener buckets and precompute listeners.
• Updated event dispatch to iterate only the listener indices for the current event category.
• Added unit tests covering bucket mapping, empty-mask rejection, and listener index construction.

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