feat(kernel): R7b C# walker — csharp module, tree-sitter-c-sharp 0.23.5 pin, csharp default-routed (#1378)

Second R7b port, checklist-first recipe (docs/design/csharp-kernel-port-checklist.md;
parity passed FIRST RUN again). No grammar bump — the #717 vendored wasm verified
table-identical to crate 0.23.5 (ABI 15, STATE_COUNT 8053, node-kind + field tables);
first port with no grammar-prep step. The #237 #if-blanking preParse stays TS-side
via the existing route-point hoist.

Walker preserves bug-for-bug: the single-namespace-node quirks (second namespace
nests under the first, nested namespaces leave no trace, import refs hang off the
namespace node), raw member-access callee texts (this./base./literal receivers,
multi-line fluent chains) with unconditional chain re-encode, deliberate emission
holes (property accessor/expression bodies, ctor initializers, delegates/events/
operators/indexers/local functions, top-level locals), garbage extends refs
((repo) primary-ctor args, BaseDto(Name) record bases, enum : byte), the alias-
import moduleName quirks, nameof-as-call, CSHARP fn-ref spec (+= subscription,
this.X bare-name form, argument layer, initializer lists), C# type-ref engine
(nested-generic returnType failure included), and value-ref shadow pruning.

Gates: sweeps 0-diff serilog 211/216 / Newtonsoft.Json 914/945 / jellyfin
2104/2105 (deferrals match the survey's per-repo predictions — both-arm #if
damage; default --max-deferral 0.1 holds, no c/cpp exemption); full-init dumps
byte-identical ×3 (14.0k/109.1k/210.8k lines); kernel-csharp-parity suite
(torture ×3 + CRLF variants + 8 micro-pins + defer) + csharp grammar-parity row;
full suite 2,608 ×2 under CODEGRAPH_KERNEL_EXPECT=1. DEFAULT_ROUTED += csharp
(11 langs).

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

codegraph-kernel/Cargo.lock

@@ -53,6 +53,7 @@ dependencies = [
  "sha2",
  "tree-sitter",
  "tree-sitter-c",
+ "tree-sitter-c-sharp",
  "tree-sitter-cpp",
  "tree-sitter-go",
  "tree-sitter-java",
@@ -495,6 +496,16 @@ dependencies = [
  "tree-sitter-language",
 ]
 
+[[package]]
+name = "tree-sitter-c-sharp"
+version = "0.23.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c1aac67f1ad71de1d6d39708d34811081c26dfa495658de6c14c34200849357c"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
 [[package]]
 name = "tree-sitter-cpp"
 version = "0.23.4"

codegraph-kernel/Cargo.toml

@@ -31,6 +31,10 @@ tree-sitter-go = "0.23"
 tree-sitter-c = "=0.24.2"
 tree-sitter-cpp = "=0.23.4"
 tree-sitter-rust = "=0.24.2"
+# csharp: the vendored wasm (#717) predates the kernel and was verified
+# table-identical to this crate's tarball (ABI 15, STATE_COUNT 8053, node-kind
+# and field tables — csharp checklist header). Bump crate + wasm together.
+tree-sitter-c-sharp = "=0.23.5"
 
 [build-dependencies]
 napi-build = "2"

codegraph-kernel/src/langs.rs

@@ -15,8 +15,8 @@ use tree_sitter::Language;
 
 /// Languages this kernel binary can extract (reported by contractInfo;
 /// TS-side routing policy decides what actually routes).
-pub const LANGUAGES: [&str; 10] =
-    ["typescript", "tsx", "javascript", "jsx", "java", "python", "go", "c", "cpp", "rust"];
+pub const LANGUAGES: [&str; 11] =
+    ["typescript", "tsx", "javascript", "jsx", "java", "python", "go", "c", "cpp", "rust", "csharp"];
 
 pub fn grammar_for(language: &str) -> Option<Language> {
     match language {
@@ -33,6 +33,9 @@ pub fn grammar_for(language: &str) -> Option<Language> {
         "cpp" => Some(tree_sitter_cpp::LANGUAGE.into()),
         // R7b: v0.24.2, sha-matched with the vendored wasm (grammars.ts).
         "rust" => Some(tree_sitter_rust::LANGUAGE.into()),
+        // R7b: 0.23.5, table-identical to the vendored ABI-15 wasm (#717;
+        // verified against the crates.io tarball — csharp checklist header).
+        "csharp" => Some(tree_sitter_c_sharp::LANGUAGE.into()),
         _ => None,
     }
 }

codegraph-kernel/src/lib.rs

@@ -19,6 +19,7 @@
 mod buffers;
 mod ccpp;
 mod cfnptr;
+mod csharp;
 mod docstring;
 mod ids;
 mod go;
@@ -213,6 +214,7 @@ pub fn extract_file(file_path: String, content: String, language: String) -> Res
         "go" => go::extract(&file_path, &content).map_err(Error::from_reason)?,
         "c" | "cpp" => ccpp::extract(&file_path, &content, &language).map_err(Error::from_reason)?,
         "rust" => rustlang::extract(&file_path, &content).map_err(Error::from_reason)?,
+        "csharp" => csharp::extract(&file_path, &content).map_err(Error::from_reason)?,
         _ => tsjs::extract(&file_path, &content, &language).map_err(Error::from_reason)?,
     };
     Ok(ExtractBuffers {