fix(module): stabilize fuzzy require resolution across duplicate suffix matches

[lewis6991]

When multiple indexed modules share the same trailing require path (for
example plugin/treesitter-context.lua and lua/treesitter-context.lua),
fuzzy lookup previously returned the first inserted candidate. Because
indexing/insertion order can vary, require('treesitter-context') could
intermittently resolve to different files and sometimes degrade to any
when a non-exporting candidate won.

This change makes fuzzy resolution deterministic by selecting the best
match using:

• smallest leading-segment count before the requested module path
• lexicographic full-module-name tie-break for stable ordering

This preserves existing fuzzy behavior while removing insertion-order
flakiness.

[gemini-code-assist]

Summary of Changes

Hello @lewis6991, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves an issue where fuzzy module resolution could be non-deterministic, leading to inconsistent module loading when multiple modules shared similar trailing paths. The changes introduce a robust selection mechanism to ensure that the same module is always chosen under identical conditions, improving reliability and predictability in module imports.

Highlights

• Stabilized Fuzzy Module Resolution: Addressed non-deterministic module resolution where multiple indexed modules with the same trailing require path could resolve inconsistently due to varying indexing/insertion order.
• New Selection Logic: Implemented a deterministic selection process that prioritizes modules with the smallest leading-segment count before the requested module path, using lexicographic ordering for tie-breaking.

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Changelog

• crates/emmylua_code_analysis/src/db_index/module/mod.rs
  • Modified fuzzy_find_module to iterate through all matching modules instead of returning the first one.
  • Introduced logic to calculate leading_segment_count for each potential module.
  • Implemented a comparison mechanism to select the "best" module based on leading_segment_count and lexicographical full_module_name.
• crates/emmylua_code_analysis/src/db_index/module/test.rs
  • Added test_require_fuzzy_match_prefers_shortest_prefix to verify that the module with the shortest prefix is chosen.
  • Added test_require_fuzzy_match_prefers_shortest_prefix_reverse_insert to confirm that insertion order does not affect the deterministic selection.

Activity

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[gemini-code-assist]

Code Review

This pull request introduces a deterministic approach for fuzzy module resolution when multiple candidates match a suffix, which is a great improvement. The logic correctly uses the leading segment count and lexicographical sorting to find the best match, resolving potential flakiness. The new tests adequately cover the implemented logic. My review includes a couple of suggestions to improve code clarity and reduce duplication.