Fix false C# symbols from named-argument framework calls

CHANGELOG.md

@@ -18,6 +18,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 - **`--exact` ranking now prefers exact-case siblings first** — When multiple symbols or graph rows collapse to the same folded exact-match key (for example `ApiClient` and `apiClient`), `symbols` / `definition` / `references` / `callers` / `callees` still return every case-insensitive exact match, but now rank the row whose stored name exactly matches the caller's casing first instead of letting path order win. This keeps the intended symbol at rank 0 for AI follow-up flows without hiding the fold-sibling rows. Added regression coverage for both symbol lookup and graph readers. Affected: `src/CodeIndex/Database/DbSymbolReader.cs`, `src/CodeIndex/Database/DbReader.cs`, `tests/CodeIndex.Tests/DbReaderTests.cs`.
 
 #### Fixed
+- **C# named-argument labels no longer masquerade as local functions in `symbols` / `deps` (#106)** — Tightened the C# explicit-interface implementation pattern so call-site lines like `isWindows: OperatingSystem.IsWindows()` are no longer parsed as fake local function definitions. This removes the downstream false positives where `symbols "IsWindows"` surfaced named-argument labels and `deps` created bogus file-level edges to those files. Added extractor-level and DbReader integration coverage for the repro shape from Praxis. Affected: `src/CodeIndex/Indexer/SymbolExtractor.cs`, `tests/CodeIndex.Tests/SymbolExtractorTests.cs`, `tests/CodeIndex.Tests/DbReaderTests.cs`. Closes #106.
 - **True Unicode CaseFold for `--exact` symbol and graph name matching (#96)** — `NameFold` now applies full Unicode CaseFold on top of NFKC normalization instead of stopping at `ToLowerInvariant()`. This closes the remaining Unicode-exact gaps for sharp-S (`Straße` / `STRASSE`), Greek final sigma (`Σ` / `ς` / `σ`), Cherokee, and other non-ASCII pairs that invariant lowercase still missed. The persisted fold-key version is bumped from 1 to 2 so existing indexes automatically degrade to ASCII `COLLATE NOCASE` until the DB truly contains only current-version fold keys, preventing silent mixed-version misses. Normal non-`--rebuild` scans remain incremental and may skip unchanged rows, so CLI and MCP indexers keep `fold_ready=false` only while unchanged old-version rows remain; if a full scan rewrites or purges every old-version row, it may safely restamp without forcing `--rebuild`. Added direct fold tests plus CLI/MCP regression coverage for sharp-S, sigma, and both sides of the mixed-version upgrade path. Locale-invariant Unicode behavior is preserved: Turkish dotted `İ` still folds to `i\u0307` rather than plain `i`, so locale-sensitive Turkish matching remains a separate follow-up. Affected: `src/CodeIndex/Database/NameFold.cs`, `src/CodeIndex/Database/DbReader.cs`, `src/CodeIndex/Database/DbWriter.cs`, `src/CodeIndex/Cli/IndexCommandRunner.cs`, `src/CodeIndex/Cli/ConsoleUi.cs`, `src/CodeIndex/Mcp/McpToolDefinitions.cs`, `src/CodeIndex/Mcp/McpToolHandlers.cs`, `tests/CodeIndex.Tests/NameFoldTests.cs`, `tests/CodeIndex.Tests/DbReaderTests.cs`, `tests/CodeIndex.Tests/IndexCommandRunnerTests.cs`, `tests/CodeIndex.Tests/McpServerTests.cs`, `README.md`. Closes #96.
 - **`exact_zero_hint` now uses a 2-phase relaxed probe on exact-miss paths (#100)** — The five exact-match surfaces (`symbols`, `definition`, `references`, `callers`, `callees`) no longer jump straight from a zero-result `--exact` query into a potentially large relaxed sample query bounded only by the user-facing limit. The relaxed hint path now does a bounded existence probe first (`LIMIT 1`), and only if that hits does it run a second bounded sample probe capped at 5 rows. Single-name lookups preserve the existing `relaxed_count` semantics under the caller's `limit`; multi-name `symbols` keeps the cheaper existence+sample path and omits `relaxed_count` rather than re-running the full round-robin merge just to count it. This keeps the additive hint behavior unchanged for callers while avoiding an unnecessary second non-SARGable substring pass when the relaxed query also returns zero, and it prevents large `--limit` values from inflating the hint cost. The same 2-phase logic now applies to the MCP zero-result hint path as well. Added regression coverage for the no-sample-on-miss behavior, the fixed 5-row cap, the preserved single-name count semantics, and the multi-name `symbols` cheap path. Affected: `src/CodeIndex/Cli/QueryCommandRunner.cs`, `src/CodeIndex/Database/DbReader.cs`, `src/CodeIndex/Database/DbSymbolReader.cs`, `src/CodeIndex/Mcp/McpToolHandlers.cs`, `src/CodeIndex/Models/QueryResults.cs`, `tests/CodeIndex.Tests/QueryCommandRunnerTests.cs`, `tests/CodeIndex.Tests/McpServerTests.cs`. Closes #100.
 - **Read-only legacy `--exact` graph queries now surface degraded index signals (#89)** — `references`, `callers`, `callees`, `inspect --exact`, and MCP `analyze_symbol` now detect when a legacy DB is missing the supporting fallback exact-match graph indexes while running in the degraded read path. Human-readable CLI output prints a WARN + reindex hint, JSON/MCP responses expose `exact_index_available` / `degraded_reason`, and bundled symbol analysis carries the same signal so AI clients can distinguish "correct but potentially slow" exact queries from normal indexed lookups. Affected: `src/CodeIndex/Database/DbReader.cs`, `src/CodeIndex/Database/DbSymbolReader.cs`, `src/CodeIndex/Cli/QueryCommandRunner.cs`, `src/CodeIndex/Mcp/McpServer.cs`, `src/CodeIndex/Mcp/McpToolHandlers.cs`, `src/CodeIndex/Models/QueryResults.cs`, `tests/CodeIndex.Tests/LegacySchemaMigrationTests.cs`, `tests/CodeIndex.Tests/QueryCommandRunnerTests.cs`, `tests/CodeIndex.Tests/McpServerTests.cs`, `README.md`. Closes #89.
@@ -625,6 +626,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 - **`--exact` の順位付けで完全一致 casing を先頭化** — `ApiClient` と `apiClient` のように folded exact-match key が同一になる複数行がある場合でも、`symbols` / `definition` / `references` / `callers` / `callees` は従来どおり大文字小文字を無視した完全一致の全行を返しつつ、呼び出し側の入力 casing と完全一致する行を path 順より優先して先頭に並べるようになった。fold sibling を隠さずに、AI の後続クエリで意図したシンボルを rank 0 に戻す。シンボル検索とグラフ reader の両方に回帰テストを追加。対象: `src/CodeIndex/Database/DbSymbolReader.cs`、`src/CodeIndex/Database/DbReader.cs`、`tests/CodeIndex.Tests/DbReaderTests.cs`。
 
 #### 修正
+- **C# named-argument label が `symbols` / `deps` でローカル関数扱いされなくなった (#106)** — C# の explicit-interface implementation pattern を締め、`isWindows: OperatingSystem.IsWindows()` のような call-site 行を偽のローカル関数定義として解釈しないようにした。これにより `symbols "IsWindows"` が named-argument label を返したり、`deps` がそのファイルへ bogus な file-level edge を張ったりする downstream false positive が解消される。Praxis の再現形に対する extractor-level と DbReader integration の回帰テストも追加。対象: `src/CodeIndex/Indexer/SymbolExtractor.cs`、`tests/CodeIndex.Tests/SymbolExtractorTests.cs`、`tests/CodeIndex.Tests/DbReaderTests.cs`。#106 をクローズ。
 - **`--exact` のシンボル名 / グラフ名マッチを true Unicode CaseFold に更新 (#96)** — `NameFold` が NFKC 正規化の後に `ToLowerInvariant()` で止まらず、full Unicode CaseFold を適用するようになった。これにより sharp-S（`Straße` / `STRASSE`）、Greek final sigma（`Σ` / `ς` / `σ`）、Cherokee など、invariant lowercase ではまだ取りこぼしていた非 ASCII の exact-match 差分を解消する。永続 fold key の version は 1 から 2 に bump され、DB に current-version の fold key だけが残るまで既存 index は自動で ASCII `COLLATE NOCASE` に降格するため、mixed-version の silent miss を防げる。通常の non-`--rebuild` scan は incremental のままで unchanged row を skip するため、CLI / MCP の indexer は旧 fold-key version の unchanged row が残っている間だけ `fold_ready=false` を維持し、full scan が旧 row をすべて rewrite / purge した場合は `--rebuild` を強制せず安全に再 stamp する。direct fold テストに加え、sharp-S / sigma と mixed-version upgrade path の両方向を固定する CLI / MCP 回帰テストも追加。Unicode の locale-invariant 挙動は維持するため、トルコ語の `İ` は引き続き plain `i` ではなく `i\u0307` に fold される。locale-sensitive な Turkish matching は別 follow-up とする。対象: `src/CodeIndex/Database/NameFold.cs`、`src/CodeIndex/Database/DbReader.cs`、`src/CodeIndex/Database/DbWriter.cs`、`src/CodeIndex/Cli/IndexCommandRunner.cs`、`src/CodeIndex/Cli/ConsoleUi.cs`、`src/CodeIndex/Mcp/McpToolDefinitions.cs`、`src/CodeIndex/Mcp/McpToolHandlers.cs`、`tests/CodeIndex.Tests/NameFoldTests.cs`、`tests/CodeIndex.Tests/DbReaderTests.cs`、`tests/CodeIndex.Tests/IndexCommandRunnerTests.cs`、`tests/CodeIndex.Tests/McpServerTests.cs`、`README.md`。Closes #96。
 - **`exact_zero_hint` が exact miss 時に 2 段階の緩和 probe を使うよう修正 (#100)** — `symbols` / `definition` / `references` / `callers` / `callees` の 5 つの exact-match 系は、`--exact` が 0 件になった直後にユーザー指定 limit までの緩和サンプルをそのまま引きに行くのではなく、まず `LIMIT 1` の existence probe を実行し、そこでヒットしたときだけ 2 本目の sample probe を最大 5 行で走らせるようになった。single-name の lookup では従来どおり caller の `limit` を反映した `relaxed_count` を維持しつつ、複数名 `symbols` だけは full の round-robin merge を数え直さず、cheap な existence+sample 経路を優先して `relaxed_count` を省略する。これにより、呼び出し側から見える additive な hint は保ちつつ、緩和側も 0 件のケースで不要な 2 回目の非 SARGable substring 走査を避けられ、大きな `--limit` 値が hint コストを膨らませることもなくなる。同じ 2 段階化は MCP の zero-result hint 経路にも適用。sample probe 非実行、5 行 cap、single-name の count 維持、複数名 `symbols` の cheap path を検証する回帰テストも追加した。対象: `src/CodeIndex/Cli/QueryCommandRunner.cs`、`src/CodeIndex/Database/DbReader.cs`、`src/CodeIndex/Database/DbSymbolReader.cs`、`src/CodeIndex/Mcp/McpToolHandlers.cs`、`src/CodeIndex/Models/QueryResults.cs`、`tests/CodeIndex.Tests/QueryCommandRunnerTests.cs`、`tests/CodeIndex.Tests/McpServerTests.cs`。Closes #100.
 - **read-only な旧DBでの `--exact` graph クエリが縮退 index シグナルを返すよう改善 (#89)** — `references`、`callers`、`callees`、`inspect --exact`、MCP `analyze_symbol` は、縮退 read path 上で fallback 用 exact-match graph index が欠けた旧DBを検出すると、人間向けCLIで WARN と再インデックスヒントを表示し、JSON/MCP では `exact_index_available` / `degraded_reason` を返すようになりました。bundle された symbol analysis も同じシグナルを持つため、AIクライアントは「結果は正しいが遅い可能性がある」exact クエリと通常の index 済み exact lookup を区別できます。対象: `src/CodeIndex/Database/DbReader.cs`, `src/CodeIndex/Database/DbSymbolReader.cs`, `src/CodeIndex/Cli/QueryCommandRunner.cs`, `src/CodeIndex/Mcp/McpServer.cs`, `src/CodeIndex/Mcp/McpToolHandlers.cs`, `src/CodeIndex/Models/QueryResults.cs`, `tests/CodeIndex.Tests/LegacySchemaMigrationTests.cs`, `tests/CodeIndex.Tests/QueryCommandRunnerTests.cs`, `tests/CodeIndex.Tests/McpServerTests.cs`, `README.md`。#89 をクローズ。

DEVELOPER_GUIDE.md

@@ -366,7 +366,7 @@ Supported symbol kinds by language (32 languages with symbol extraction):
 | Python | def, async def | class | -- | -- | -- | @property | -- | from/import | yes |
 | JavaScript | function, arrow, methods | class | -- | -- | -- | -- | -- | import...from | yes |
 | TypeScript | function, arrow, methods | class, type | -- | interface | enum, const enum | -- | -- | import...from | yes |
-| C# | methods, ctors, operators, indexers, const, static readonly, enum members, #region, finalizers | class, record | struct, record struct, ref struct | interface | enum | property, expression-bodied | event, delegate | using, using alias | yes |
+| C# | methods, ctors, explicit-interface impls (guards named-argument labels), operators, indexers, const, static readonly, enum members, #region, finalizers | class, record | struct, record struct, ref struct | interface | enum | property, expression-bodied | event, delegate | using, using alias | yes |
 | Go | func, methods | type alias | struct | interface | -- | -- | -- | import | yes |
 | Rust | fn, macro_rules!, const, static | impl, type alias | struct, union | trait | enum | -- | -- | use | yes |
 | Java | methods, static final, enum members | class, record, sealed, @interface | -- | interface | enum | -- | -- | import | yes |
@@ -1286,7 +1286,7 @@ LIMIT 20;
 | Python | def, async def | class | -- | -- | -- | @property | -- | from/import | yes |
 | JavaScript | function, アロー, メソッド | class | -- | -- | -- | -- | -- | import...from | yes |
 | TypeScript | function, アロー, メソッド | class, type | -- | interface | enum, const enum | -- | -- | import...from | yes |
-| C# | メソッド, コンストラクタ, 演算子, インデクサ, const, static readonly, enum メンバー, #region, ファイナライザ | class, record | struct, record struct, ref struct | interface | enum | property, 式本体 | event, delegate | using, using alias | yes |
+| C# | メソッド, コンストラクタ, explicit-interface 実装（named-argument label は除外）, 演算子, インデクサ, const, static readonly, enum メンバー, #region, ファイナライザ | class, record | struct, record struct, ref struct | interface | enum | property, 式本体 | event, delegate | using, using alias | yes |
 | Go | func, メソッド | 型エイリアス | struct | interface | -- | -- | -- | import | yes |
 | Rust | fn, macro_rules!, const, static | impl, type alias | struct, union | trait | enum | -- | -- | use | yes |
 | Java | メソッド, static final, enum メンバー | class, record, sealed, @interface | -- | interface | enum | -- | -- | import | yes |

src/CodeIndex/Indexer/SymbolExtractor.cs

@@ -107,9 +107,11 @@ private sealed record SymbolPattern(
             new("event",     new Regex(@"^\s*(?:(?<visibility>public|private|protected\s+internal|private\s+protected|protected|internal)\s+)?(?:(?:static)\s+)?event\s+\S+\s+(?<name>\w+)", RegexOptions.Compiled), BodyStyle.None, "visibility"),
             // Explicit interface implementation (e.g. void IDisposable.Dispose())
             // Requires a valid return type (not a statement keyword) and interface name before the dot.
+            // Also reject named-argument labels like `isWindows: OperatingSystem.IsWindows()`.
             // 明示的インターフェース実装 (例: void IDisposable.Dispose())
             // 有効な戻り値型（ステートメントキーワードではない）とドット前のインターフェース名を要求。
-            new("function",  new Regex(@"^\s*(?!(?:await|return|throw|yield|var|typeof|sizeof|nameof|default|if|for|foreach|while|switch|catch|lock|using|case|else|when|break|continue|goto)\b)(?<returnType>(?:global::)?[\w?.<>\[\],:]+)\s+[\w.<>]+\.(?<name>\w+)\s*(?:<[^>]+>\s*)?[\(\[]", RegexOptions.Compiled), BodyStyle.Brace, ReturnTypeGroup: "returnType"),
+            // `isWindows: OperatingSystem.IsWindows()` のような named-argument label も除外する。
+            new("function",  new Regex(@"^\s*(?!(?:await|return|throw|yield|var|typeof|sizeof|nameof|default|if|for|foreach|while|switch|catch|lock|using|case|else|when|break|continue|goto)\b)(?!\w+\s*:)(?<returnType>(?:global::)?[\w?.<>\[\],:]+)\s+[\w.<>]+\.(?<name>\w+)\s*(?:<[^>]+>\s*)?[\(\[]", RegexOptions.Compiled), BodyStyle.Brace, ReturnTypeGroup: "returnType"),
             // Indexer (this[...]) / インデクサ (this[...])
             new("function",  new Regex(@"^\s*(?:(?<visibility>public|private|protected\s+internal|private\s+protected|protected|internal)\s+)?(?:(?:static|virtual|override|abstract|sealed|new)\s+)*(?<returnType>(?:global::)?[\w?.<>\[\],:]+)\s+(?<name>this)\s*\[", RegexOptions.Compiled), BodyStyle.Brace, "visibility", "returnType"),
             // Static constructor / 静的コンストラクタ

tests/CodeIndex.Tests/DbReaderTests.cs

@@ -239,6 +239,32 @@ public void SearchSymbols_FindsByName()
         Assert.Equal("src/auth.py", results[0].Path);
     }
 
+    [Fact]
+    public void SearchSymbols_AndDeps_DoNotTreatNamedArgumentLabelsAsLocalFunctions()
+    {
+        InsertIndexedFile("src/platform.cs", "csharp",
+            """
+            public class PlatformState
+            {
+                public static bool Detect() =>
+                    new Options(
+                        isWindows: OperatingSystem.IsWindows(),
+                        isMacCatalyst: OperatingSystem.IsMacCatalyst()).Ready;
+            }
+            """);
+        InsertIndexedFile("src/app.cs", "csharp",
+            """
+            public class App
+            {
+                public bool Read() => OperatingSystem.IsWindows() || OperatingSystem.IsMacCatalyst();
+            }
+            """);
+
+        Assert.Empty(_reader.SearchSymbols("IsWindows", lang: "csharp"));
+        Assert.Empty(_reader.SearchSymbols("IsMacCatalyst", lang: "csharp"));
+        Assert.Empty(_reader.GetFileDependencies(lang: "csharp"));
+    }
+
     [Fact]
     public void SearchSymbols_ReturnsRichMetadataWhenAvailable()
     {

tests/CodeIndex.Tests/SymbolExtractorTests.cs

@@ -988,6 +988,32 @@ public void Extract_CSharp_DoesNotMatchQualifiedCallSitesAsDefinitions()
         Assert.DoesNotContain(symbols, s => s.Name == "CreateException");
     }
 
+    [Fact]
+    public void Extract_CSharp_DoesNotMatchNamedArgumentFrameworkCallsAsDefinitions()
+    {
+        // Named-argument labels preceding qualified framework calls must not look like explicit interface impls.
+        // 修飾付き framework call の前にある named-argument label を明示的インターフェース実装と誤認しないこと。
+        var content = """
+            public class PlatformState
+            {
+                public PlatformState(bool isWindows, bool isMacCatalyst)
+                {
+                }
+
+                public static PlatformState Detect() =>
+                    new(
+                        isWindows: OperatingSystem.IsWindows(),
+                        isMacCatalyst: OperatingSystem.IsMacCatalyst());
+            }
+            """;
+        var symbols = SymbolExtractor.Extract(1, "csharp", content);
+
+        Assert.Contains(symbols, s => s.Kind == "class" && s.Name == "PlatformState");
+        Assert.Contains(symbols, s => s.Kind == "function" && s.Name == "Detect");
+        Assert.DoesNotContain(symbols, s => s.Name == "IsWindows");
+        Assert.DoesNotContain(symbols, s => s.Name == "IsMacCatalyst");
+    }
+
     [Fact]
     public void Extract_CSharp_DetectsNewModifierMethods()
     {