[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/server/completion.ts

@@ -442,6 +442,17 @@ async function addIdentifierCompletion(
       kind,
     };
 
+    // skip indexer/docFromComment functions under TypeSpec namespace
+    // these are internal only functions(decorators) that should not be exposed to users
+    if (
+      (item.label === "indexer" || item.label === "docFromComment") &&
+      item.kind === CompletionItemKind.Function &&
+      sym.parent?.name === "TypeSpec" &&
+      item.documentation === undefined
+    ) {
+      continue;
+    }
+
     if (sym.name.startsWith("$")) {
       const targetNode = getSourceLocation(node);
       const lineAndChar = targetNode.file.getLineAndCharacterOfPosition(node.pos);