make the whole projectContext still a reference after safeCloneDeep

src/core/safe-clone-deep.ts

@@ -6,6 +6,8 @@
  * Copyright (C) 2025 Posit Software, PBC
  */
 
+// This is used to create new interfaces that extend the Cloneable interface
+// to make the object having a clone method for specific cloning behavior in safeCloneDeep.
 export interface Cloneable<T> {
   clone(): T;
 }

src/project/project-context.ts

@@ -275,6 +275,7 @@ export async function projectContext(
         });
         const fileInformationCache = new FileInformationCacheMap();
         const result: ProjectContext = {
+          clone: () => result,
           resolveBrand: async (fileName?: string) =>
             projectResolveBrand(result, fileName),
           resolveFullMarkdownForFile: (
@@ -371,6 +372,7 @@ export async function projectContext(
         });
         const fileInformationCache = new FileInformationCacheMap();
         const result: ProjectContext = {
+          clone: () => result,
           resolveBrand: async (fileName?: string) =>
             projectResolveBrand(result, fileName),
           resolveFullMarkdownForFile: (
@@ -446,6 +448,7 @@ export async function projectContext(
           });
           const fileInformationCache = new FileInformationCacheMap();
           const context: ProjectContext = {
+            clone: () => context,
             resolveBrand: async (fileName?: string) =>
               projectResolveBrand(context, fileName),
             resolveFullMarkdownForFile: (

src/project/types.ts

@@ -22,6 +22,7 @@ import {
 import { ProjectEnvironment } from "./project-environment-types.ts";
 import { ProjectCache } from "../core/cache/cache-types.ts";
 import { TempContext } from "../core/temp-types.ts";
+import { Cloneable } from "../core/safe-clone-deep.ts";
 
 export {
   type NavigationItem as NavItem,
@@ -58,7 +59,7 @@ export type FileInformation = {
   brand?: LightDarkBrand;
 };
 
-export interface ProjectContext {
+export interface ProjectContext extends Cloneable<ProjectContext> {
   dir: string;
   engines: string[];
   files: ProjectFiles;

src/project/types/single-file/single-file.ts

@@ -41,6 +41,7 @@ export async function singleFileProjectContext(
   const projectCacheBaseDir = temp.createDir();
 
   const result: ProjectContext = {
+    clone: () => result,
     resolveBrand: (fileName?: string) => projectResolveBrand(result, fileName),
     dir: normalizePath(dirname(source)),
     engines: [],