Sort prefix matches above other contain matches

[myieye]

The updated test cases demonstrate the intention of this PR.

We got the feedback:

filtering for 'tan' gave entries: Antan, matan, tana', tanam, tanan ... and I wondered why Antan and matan were listed before tana', tanam, tanan? If the user thinks they know the beginning of the word, then shouldn't those entries come first? Then other words with 'tan' in them?

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📝 Walkthrough

Walkthrough

This PR introduces diacritic-aware prefix matching functionality to complement existing contains matching. It adds StartsWithDiacriticMatch and ContainsDiacriticMatch methods to string utilities, registers a new SQLite StartsWith function, updates sorting logic to prioritize prefix matches, enhances the search service with a new FilterAndRank method, and adjusts test expectations to reflect the new ranking behavior.

Changes

Cohort / File(s)	Summary
String matching utilities backend/FwLite/MiniLcm/Culture/StringExtensions.cs, backend/FwLite/LcmCrdt/SqlHelpers.cs	Replaced public Contains method with ContainsDiacriticMatch and StartsWithDiacriticMatch for diacritic-aware string matching. Added StartsWithIgnoreCaseAccents SQL expression method to SqlHelpers with diacritic-insensitive semantics.
SQLite function registration backend/FwLite/LcmCrdt/Data/CustomSqliteFunctionInterceptor.cs	Renamed RegisterContainsFunction to RegisterCustomFunctions, added new StartsWithFunction constant and implementation, introduced DiacriticMatchOptions helper for determining comparison options based on diacritic presence.
Sorting and ranking logic backend/FwLite/FwDataMiniLcmBridge/Api/Sorting.cs, backend/FwLite/LcmCrdt/Data/Sorting.cs, backend/FwLite/LcmCrdt/FullTextSearch/EntrySearchService.cs	Added prefix-match ranking clauses to sorting logic in both Sorting files. Added new public FilterAndRank method to EntrySearchService with multi-criteria ordering: headword matches, then prefix matches, then length/text, with FTS rank and ID tiebreakers. Updated FilterProjection record to include HeadwordPrefixMatches flag.
Test expectations backend/FwLite/MiniLcm.Tests/QueryEntryTestsBase.cs	Updated test data expectations for att-related cases to reflect new prefix-based ranking order: changed from att,zatt,attack,battery,rap to att,attack,zatt,battery,rap.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• implement accent/diacritic ignore search #1724: Introduces foundational diacritic-aware contains matching infrastructure that this PR extends with prefix matching across string utilities, SQL functions, and ranking logic.
• Make headword matches trump fts rank #2112: Modifies EntrySearchService.FilterAndRank to prioritize headword and headword prefix matches in the same ranking pipeline.
• Fix FTS5 syntax errors when searching with punctuation characters #2085: Modifies EntrySearchService.FilterAndRank with FTS query escaping that integrates with the new filtering and ranking functionality.

Suggested labels

💻 FW Lite

Suggested reviewers

• imnasnainaec

Poem

🐰 A rabbit hops through prefix dreams,
Where matches dance in diacritic streams,
No accent marks can hide from sight,
With StartsWith bringing ranking might! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 26.32% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: prioritizing prefix matches above other contain matches in sorting, which directly aligns with the PR's primary objective and all modified files.
Description check	✅ Passed	The description relates to the changeset by explaining the motivation behind the sorting changes with user feedback about prefix matches being prioritized.

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch sort-prefix-matches-before-other-contain-matches

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[github-actions]

UI unit Tests

  1 files  ±0   50 suites  ±0   23s ⏱️ -1s
138 tests ±0  138 ✅ ±0  0 💤 ±0  0 ❌ ±0 
203 runs  ±0  203 ✅ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit e9ceb65. ± Comparison against base commit a43a321.

♻️ This comment has been updated with latest results.

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Build	Status	Details	Updated (UTC)
default (Inspect)	✅ No changes detected	-	Feb 10, 2026, 3:43 PM