Command Palette: exact match should always go first

[michaeljolley]

Summary

Fixes #48533

When typing a query in Command Palette that exactly matches a command's title (e.g., "Terminal"), the exact match now ranks first in results instead of being outranked by longer strings containing the query (e.g., "Windows Terminal").

Changes

MainListPage.cs — Added a title-match boost in ScoreTopLevelItem():

• Exact title match (case-insensitive): +9000 boost (just below alias exact match at 9001)
• Title starts with query (case-insensitive): +100 boost (above normal fuzzy scores)

This follows the same pattern as the existing alias boost and the Windows Settings extension's ScoringHelper.

Score hierarchy

Priority	Condition	Boost
1	Alias exact match	9001
2	Title exact match (new)	9000
3	Title starts with query (new)	100
4	Normal fuzzy score	~10-50

Testing

Added MainListPageScoringTests.cs with 5 test cases:

• Exact title match scores higher than substring match
• Case-insensitive exact match works
• Prefix match scores higher than substring match
• Alias exact match still wins over title exact match
• Multi-candidate ranking (exact > prefix > contains)

All 123 existing tests continue to pass.

[zadjii-msft]

I'm not sure this is the correct solution here.

Exact matches are good to boost, sure. But like, even in the case of something like ter - that should match "Terminal" before the "open terminal profiles" command.

From what I'm seeing, it's the extension name boost that's throwing things off here. "Open Terminal Profiles" also gets boosted by the extensionScore, which Terminal doesn't.

I tried just swapping

-        var matchScore = baseScore + extensionScore;
+        var matchScore = Math.Max(baseScore, extensionScore);

and that fixes the "terminal" case, but it doesn't help for like, the "Teams meeting control" case:

cause there, the exact match at the beginning of the string still boosts it above Teams itself.

I may just see if doubling the string match score for apps helps feel right.

[michaeljolley]

I'm not sure this is the correct solution here.

Exact matches are good to boost, sure. But like, even in the case of something like ter - that should match "Terminal" before the "open terminal profiles" command.

From what I'm seeing, it's the extension name boost that's throwing things off here. "Open Terminal Profiles" also gets boosted by the extensionScore, which Terminal doesn't.

Not sure I completely agree. Few thoughts:

1. The issue/PR is solely focused on exact matches. In those instances, I agree with the OP that exact match should land at position 1 (or zero 😄), period.
2. We could say "nah, let's address search overall" and that would be valid, but it wasn't really in the scope of what I was doing.
   • On that point, why are we scoring things by unseen values (like extension name)? It opens up questions from users as to why they're seeing odd results and disincentivizes extension developers from using title/subtitle better.

I'm not saying the change you suggested is bad, but it leaves ambiguity as to whether a result that is an exact match shows up in the first position.