Sprints 273-276: Polyglot FFI Glue, Symbol Index, and LSP Proxy (steps 1893-1912)

Sprint 273 — PolyglotFFIGlueGenerator (steps 1893-1897):
  ABIBoundaryExtractor, CHeaderEmitter, RustPythonBindingEmitter,
  GoCppBindingEmitter. Extracts exported symbols from toComponent provider
  and emits C ABI + language-specific bindings.

Sprint 274 — More Binding Pairs + DWARF (steps 1898-1902):
  CppJSBindingEmitter (N-API), RustGoBindingEmitter (#[no_mangle]),
  DWARFBoundaryAnnotator (DW_TAG_* + crossLangBoundary),
  FFIGlueDispatcher (routes by fromLang→toLang pair),
  MCP tool whetstone_generate_ffi_glue (#92).

Sprint 275 — Cross-Language Symbol Index (steps 1903-1907):
  SCIPEmitter (SCIP JSON, one doc/language, caller+provider roles),
  CrossLanguageSymbolTable (byLangName_ + byScip_ dual index),
  SymbolIndexUpdater (nodeKey diff, clear-and-rebuild),
  SymbolIndexOrchestrator (orchestrate + update),
  MCP tool whetstone_emit_symbol_index (#93).

Sprint 276 — LSP Proxy Core (steps 1908-1912):
  LSPProxyServer (JSON-RPC 2.0 dispatcher),
  LanguageServerRouter (routeByUri/routeByLanguageId),
  CrossLanguageBoundaryDetector (detect/detectWithUri/detectInLanguage),
  CrossLanguageDefinitionResolver (resolve/resolveFromUri → DefinitionLocation).
  End-to-end: Python call site goto-def resolves to Rust sort-core provider.

100/100 tests passing across all four sprints. Architecture gate clean.
LoRA sessions recorded for all sprints (~14k tokens captured).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

editor/tests/step1908_test.cpp

@@ -0,0 +1,119 @@
+// Step 1908: LSPProxyServer
+// LSP protocol handler (JSON-RPC 2.0) that receives requests and dispatches them.
+// Models per-language servers as stubs — no real network required.
+//
+//  t1: initialize request returns capabilities response with correct id
+//  t2: textDocument/definition dispatches and returns a result object
+//  t3: textDocument/hover dispatches and returns a result object
+//  t4: unknown method returns JSON-RPC error (code -32601 method not found)
+//  t5: notification (no id) is handled without returning a response
+
+#include "LSPProxyServer.h"
+#include <iostream>
+#include <string>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+namespace ws = whetstone;
+
+static int p=0,f=0;
+#define T(n) { std::cout<<"  "<<#n<<"... "; }
+#define P() { std::cout<<"PASS\n"; ++p; }
+#define F(m) { std::cout<<"FAIL: "<<m<<"\n"; ++f; }
+#define C(c,m) if(!(c)){F(m);return;}
+
+static json makeRequest(int id, const std::string& method, json params = json::object()) {
+    return {{"jsonrpc","2.0"},{"id",id},{"method",method},{"params",params}};
+}
+
+static json makeNotification(const std::string& method, json params = json::object()) {
+    return {{"jsonrpc","2.0"},{"method",method},{"params",params}};
+}
+
+void t1(){
+    T(initialize_request_returns_capabilities_with_correct_id);
+    ws::LSPProxyServer server;
+    auto req = makeRequest(1, "initialize", {{"capabilities",json::object()}});
+
+    auto resp = server.handle(req);
+
+    C(resp.contains("id") && resp["id"] == 1,
+      "response id must match request id");
+    C(resp.contains("result"),
+      "initialize must return a result");
+    C(resp["result"].contains("capabilities"),
+      "result must have capabilities");
+    P();
+}
+
+void t2(){
+    T(textDocument_definition_dispatches_returns_result);
+    ws::LSPProxyServer server;
+    auto req = makeRequest(2, "textDocument/definition", {
+        {"textDocument", {{"uri","file:///sort.py"}}},
+        {"position",     {{"line",5},{"character",10}}}
+    });
+
+    auto resp = server.handle(req);
+
+    C(resp.contains("id") && resp["id"] == 2,
+      "response id must be 2");
+    C(resp.contains("result"),
+      "textDocument/definition must return result (may be null)");
+    P();
+}
+
+void t3(){
+    T(textDocument_hover_dispatches_returns_result);
+    ws::LSPProxyServer server;
+    auto req = makeRequest(3, "textDocument/hover", {
+        {"textDocument", {{"uri","file:///sort.py"}}},
+        {"position",     {{"line",5},{"character",10}}}
+    });
+
+    auto resp = server.handle(req);
+
+    C(resp.contains("id") && resp["id"] == 3,
+      "response id must be 3");
+    C(resp.contains("result"),
+      "textDocument/hover must return result");
+    P();
+}
+
+void t4(){
+    T(unknown_method_returns_method_not_found_error);
+    ws::LSPProxyServer server;
+    auto req = makeRequest(4, "textDocument/nonexistent", json::object());
+
+    auto resp = server.handle(req);
+
+    C(resp.contains("id") && resp["id"] == 4,
+      "error response must echo id");
+    C(resp.contains("error"),
+      "unknown method must return error");
+    C(resp["error"].contains("code") && resp["error"]["code"] == -32601,
+      "error code must be -32601 (MethodNotFound)");
+    P();
+}
+
+void t5(){
+    T(notification_handled_without_response);
+    ws::LSPProxyServer server;
+    auto notif = makeNotification("textDocument/didOpen", {
+        {"textDocument", {{"uri","file:///sort.py"},{"languageId","python"},{"version",1},{"text",""}}}
+    });
+
+    auto resp = server.handle(notif);
+
+    // Notifications must not produce a response (return null/empty JSON)
+    C(resp.is_null() || (resp.is_object() && resp.empty()),
+      "notification must return null or empty JSON, not a response");
+    P();
+}
+
+int main(){
+    std::cout << "Step 1908: LSPProxyServer\n";
+    t1(); t2(); t3(); t4(); t5();
+    std::cout << "\n" << p << "/" << (p+f) << " passed\n";
+    return f > 0 ? 1 : 0;
+}