perf(lambda-rs-args): Prune candidates shorter than the best levenshtein distance

[vmarcella]

Summary

Improve unknown-argument suggestion performance in lambda-rs-args by pruning candidates that cannot beat the current best Levenshtein distance based on character-length lower bounds.

Related Issues

N/A

Changes

• Added an early-prune in unknown_with_suggestion to skip Levenshtein calls when abs(len(key) - len(arg)) >= best_distance.
• Kept suggestion output behavior unchanged (did you mean ...).
• Added stress coverage with many unrelated flags to validate suggestion quality under larger candidate sets.

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-args

Manual verification steps (if applicable):

1. Trigger parse with an unknown flag similar to a known one (e.g. --portt vs --port) and verify suggestion output remains correct.

Screenshots/Recordings

N/A

Platform Testing

• macOS
• Windows
• Linux

Additional Notes

Asymptotics: worst-case remains O(A * L^2) for A candidate args and L string length, but the prune reduces expensive Levenshtein evaluations from O(A) to O(K) in common cases (K <= A) where many candidates are length-mismatched.

[github-actions]

✅ Coverage Report

📊 View Full HTML Report (download artifact)

Overall Coverage

Metric	Value
Total Line Coverage	76.92%
Lines Covered	12700 / 16511

Changed Files in This PR

File	Coverage	Lines
crates/lambda-rs-args/src/lib.rs	75.94%	767/1010

PR Files Coverage: 75.94% (767/1010 lines)

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_{Last updated: 2026-03-12 19:59:30 UTC · Commit: 245dfa1}