Fuzzy filter with a leading or trailing space hides every item: " hel" matches nothing, "hel " matches only items containing a space

[matt-edmondson]

What's wrong

The Fuzzy arm of IsMatch (TextFilter/TextFilter.cs:242) passes the filter to the fuzzy matcher exactly as typed:

TextFilterType.Fuzzy => Fuzzy.Contains(text.AsSpan(), filter.AsSpan(), out score),

A leading or trailing space therefore becomes a character the text must contain.

The other filter types don't behave this way. Glob and Regex split the filter into tokens, so padding has no effect. IsMatch itself already treats a filter that is only whitespace as "match everything". Fuzzy is the one type where a stray space changes the result.

Failure scenario

In a filter box, the user types a word, then a space before the next word. Every item without a space disappears. Leading spaces from a paste do the same.

With items {"hello world", "helium", "help", "yellow"}:

Filter	Type	Result	Expected
"hel"	Fuzzy	[help, helium, hello world]	same
"hel "	Fuzzy	[hello world]	[help, helium, hello world]
" hel"	Fuzzy	[]	[help, helium, hello world]
" hel*"	Glob	[hello world, helium, help]	same

IsMatch("abcdef", "abc", Fuzzy) is true, but "abc " and " abc" both return false. Rank is unaffected, because it ignores the match result.

These results come from a scratch program built from the current TextFilter.cs against the pinned ktsu.FuzzySearch:

Fuzzy filter='hel' -> [help, helium, hello world]
Fuzzy filter='hel ' -> [hello world]
Fuzzy filter=' hel' -> []

Suggested fix

• Trim the filter before the fuzzy match: Fuzzy.Contains(text.AsSpan(), filter.AsSpan().Trim(), out score).
• Optionally, go further and apply TextFilterMatchOptions to fuzzy matching: split on whitespace and match each token, the way the glob path does. That would make "bar foo" fuzzy-match "foo bar". Today the match-options argument is silently ignored for Fuzzy.

Acceptance criteria

• IsMatch(x, "hel ", Fuzzy) and IsMatch(x, " hel", Fuzzy) return the same result as IsMatch(x, "hel", Fuzzy) for every x.
• Regression tests cover leading and trailing padding in Filter and IsMatch for Fuzzy.

[matt-edmondson]

Triage

• Category: Bug
• Priority: Medium. In an interactive filter box, typing a space between words makes most results disappear, and every UI built on TextFilter's Fuzzy mode inherits this. There's no data loss, and the fix is a one-line trim.
• Area: the Fuzzy arm of IsMatch in TextFilter/TextFilter.cs.
• Suggested assignment: TextFilter maintainer. No specific team.
• Duplicates / in progress: none found in this repo, and there's no open PR.
• Suggested next step: ship filter.AsSpan().Trim() with the padding regression tests now. Token-splitting for Fuzzy, which would honour TextFilterMatchOptions, is a behaviour change and belongs in a separate issue or PR.

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