Mechanical update of all call sites following the PatternMatcher refactor:
- DeclarationFinder: explicit allowFuzzyMatching: false, includeMatchedSpans: false
- DocumentOutlineViewModel: add missing using on PatternMatcher
- PatternMatcherTests: explicit allowFuzzyMatching: false

Co-authored-by: Cursor <cursoragent@cursor.com>

Change StringBreaker's public API from string to ReadOnlySpan<char> parameters (AddWordParts,
AddCharacterParts, AddParts, GenerateSpan) and all internal helpers. This enables span-based
processing in the new NavigateTo prefilter code without allocating substrings.

Co-authored-by: Cursor <cursoragent@cursor.com>

Add ComputeHash(ReadOnlySpan<char>) and GetCharacter(ReadOnlySpan<char>) overloads.
Refactor ComputeHash(string) to delegate to the span overload. Simplify Add(char) and
ProbablyContains(char) to delegate to the span overloads. Add doc remark on
ProbablyContains(ReadOnlySpan<char>) explaining why it cannot share the caching
optimization from the string overload. This enables allocation-free bloom filter
operations in the NavigateTo prefilter.

Co-authored-by: Cursor <cursoragent@cursor.com>

Move the NavigateTo pre-filter data out of TopLevelSyntaxTreeIndex into its own
NavigateToSearchIndex (a new AbstractSyntaxIndex<NavigateToSearchIndex> subclass).
This allows the lightweight filter data to be loaded independently of the heavyweight
TopLevelSyntaxTreeIndex containing all declared symbols. Documents rejected by the
filter never need to load the full index.

Bump serialization format checksum from "51" to "52" to invalidate stale indices.

- New: NavigateToSearchIndex.cs, _Create.cs, _Persistence.cs
- TopLevelSyntaxTreeIndex: remove _navigateToSearchInfo field and related code

Co-authored-by: Cursor <cursoragent@cursor.com>

…grams, and length bitset

The core pre-filtering logic for NavigateTo, stored per-document in the NavigateToSearchIndex.
Contains five bloom filters and a length bitset for fast document-level rejection:

- _humpCharFilter: individual uppercased hump-initial characters (e.g. 'G','B' for "GooBar")
- _humpBigramFilter: all C(k,2) ordered pairs of hump initials (e.g. "GB","GQ","BQ" for
  "GooBarQuux"), enabling non-contiguous CamelCase matching
- _humpPrefixFilter: lowercased prefixes of each hump (e.g. "g","go","goo","b","ba","bar"
  for "GooBar"), used by a DP algorithm for all-lowercase patterns
- _trigramFilter: 3-char sliding windows for LowercaseSubstring matching (e.g. "line" in
  "Readline")
- _containerFilter: hump chars from fully-qualified container names
- _symbolNameLengthBitset: 64-bit bitset for fuzzy match length pre-filtering

For all-lowercase patterns, a DP algorithm splits the pattern into segments that each match
a stored hump prefix, avoiding the exponential capitalization enumeration.

Includes extensive documentation with examples throughout.

Co-authored-by: Cursor <cursoragent@cursor.com>

Integrate the lightweight NavigateToSearchIndex pre-filter into both the in-process and
cached document search paths:

- InProcess: load the filter index first via NavigateToSearchIndex.GetRequiredIndexAsync,
  call CouldContainNavigateToMatch to decide whether to load the full TopLevelSyntaxTreeIndex.
  Pass the allowFuzzyMatching signal from the filter to the PatternMatcher.
- CachedDocumentSearch: add s_cachedFilterIndexMap for the filter index, load it before the
  full index in the parallel ForEachAsync loop.
- Add LowercaseSubstring -> Fuzzy mapping to s_kindPairs.

Co-authored-by: Cursor <cursoragent@cursor.com>

~1030 lines of declarative theory-based tests covering all match kinds and pre-filter
behaviors. Organized into regions:

- Positive tests: verify CouldContainNavigateToMatch returns true for all supported
  PatternMatchKinds (Exact, Prefix, CamelCaseExact/Prefix/Substring, NonContiguous
  variants, StartOfWordSubstring, LowercaseSubstring, Fuzzy) with both mixed-case
  and all-lowercase patterns
- Negative tests: verify rejection when hump chars, bigrams, trigrams, and lengths
  don't match
- CrossHumpSubstring: documents NonLowercaseSubstring as intentionally not guaranteed
- Multiple symbols: document-level filter matches any symbol
- Fuzzy/non-fuzzy split: verify allowFuzzyMatching output signal
- Individual filter checks via TestAccessor (hump, DP, trigram, length)
- Container matching tests

Co-authored-by: Cursor <cursoragent@cursor.com>

End-to-end tests verifying that the NavigateToSearchIndex pre-filter correctly allows
matches through the full NavigateTo pipeline:

- CamelCase hump bigram (GB -> GooBar)
- All-lowercase DP hump prefix (goo -> GooBar)
- Trigram substring (line -> Readline)
- Fuzzy match enabled by length check (ToEror -> ToError)
- No match when all checks fail (XyzXyzXyzXyz)

Co-authored-by: Cursor <cursoragent@cursor.com>

BenchmarkDotNet benchmarks for measuring NavigateToSearchIndex pre-filter performance
across various pattern types (CamelCase, all-lowercase, trigram, fuzzy, container-qualified).

Co-authored-by: Cursor <cursoragent@cursor.com>

…th thresholds

The existing fuzzy pre-filter used only a symbol-name-length bitset with a
fixed ±2 delta, which was too coarse — in large files, many symbols share
similar lengths, causing false positives that force expensive full-scan
fuzzy matching.

This commit improves the pre-filter in three ways:

1. Fix LengthCheckPasses to use WordSimilarityChecker.GetThreshold (±1 for
   pattern lengths 3–4, ±2 for 5+) and reject patterns < MinFuzzyLength (3),
   matching the actual fuzzy matching behavior.

2. Add a 37×37 exact bigram bitset (176 bytes per document) storing all
   lowercased 2-character sliding windows of symbol names. At query time,
   use Ukkonen's q-gram count lemma to compute a minimum shared bigram
   count: min_shared = |pattern| - 1 - 2k. If fewer pattern bigrams match,
   fuzzy matching is skipped for that document.

3. Extract WordSimilarityChecker.GetThreshold(int) overload and MinFuzzyLength
   constant so both the pre-filter and the actual fuzzy matcher share the
   same threshold logic.

Reference: Ukkonen, E. (1992). "Approximate string-matching with q-grams
and maximal matches." Theoretical Computer Science, 92(1), 191–211.
https://doi.org/10.1016/0304-3975(92)90143-4

Co-authored-by: Cursor <cursoragent@cursor.com>

Extract edit-distance (fuzzy) matching from the shared PatternMatcher
pipeline into a standalone FuzzyPatternMatcher class. Previously the
allowFuzzyMatching bool threaded through 7 locations (factory, constructor,
PatternSegment, TextChunk, AddMatches, MatchPatternSegment, MatchPatternChunk).
Now each matcher has a single responsibility:

- SimplePatternMatcher: exact, prefix, camelCase, substring (non-fuzzy)
- FuzzyPatternMatcher: edit-distance only (WordSimilarityChecker)
- ContainerPatternMatcher: dot-separated container matching (non-fuzzy)

Callers compose them: try non-fuzzy first, fuzzy only as fallback — no
redundant work. NavigateToSearchInfo now returns two independent signals
(couldNonFuzzyMatch, couldFuzzyMatch) instead of a single bool.

Also refactors base PatternMatcher: AddMatches is now non-abstract and
handles SkipMatch centrally, delegating to abstract AddMatchesWorker.

Co-authored-by: Cursor <cursoragent@cursor.com>

Replace the two-boolean prefilter signal (couldNonFuzzyMatch, couldFuzzyMatch)
and manual matcher composition with a [Flags] enum PatternMatcherKind
{ None, Standard, Fuzzy } that flows from the prefilter through the factory.

CreatePatternMatcher now accepts a PatternMatcherKind parameter:
- Standard only -> SimplePatternMatcher
- Fuzzy only -> FuzzyPatternMatcher
- Standard | Fuzzy -> CompoundPatternMatcher (tries each in order,
  short-circuits on first match)

CompoundPatternMatcher takes ReadOnlySpan<PatternMatcher> and manages an
internal ArrayBuilder, freed on dispose. Callers no longer need to manually
compose matchers — they pass the enum and get the right thing back.

NavigateToSearchIndex.CouldContainNavigateToMatch now returns
PatternMatcherKind instead of bool + two out params.

Co-authored-by: Cursor <cursoragent@cursor.com>

…o-fuzzy-bigram-bitset

…/separate-fuzzy-pattern-matcher

…e-fuzzy-pattern-matcher

…zzy-threshold