[typespec-vscode] Compiler internal decorators shouldn't be listed in autocomplete

.chronus/changes/compiler-internal-decorators-not-show-in-autocomplete-2025-9-22-6-58-42.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/compiler"
+---
+
+Compiler internal decorators shouldn't be listed in autocomplete

packages/compiler/src/core/name-resolver.ts

@@ -1091,7 +1091,15 @@ export function createResolver(program: Program): NameResolver {
           mergedSymbols.set(sourceBinding, targetBinding);
           mutate(targetBinding.declarations).push(...sourceBinding.declarations);
 
-          mergeSymbolTable(sourceBinding.exports!, mutate(targetBinding.exports!));
+          // Create filtered exports table excluding internal decorators
+          const filteredExports = createSymbolTable();
+          for (const [exportKey, exportSymbol] of sourceBinding.exports!) {
+            // Skip internal decorators that should not be exposed
+            if (exportKey !== "@indexer" && exportKey !== "@docFromComment") {
+              mutate(filteredExports).set(exportKey, exportSymbol);
+            }
+          }
+          mergeSymbolTable(filteredExports, mutate(targetBinding.exports!));
         } else {
           // this will set a duplicate error
           target.set(key, sourceBinding);