feat(desktop): link Markdown files and folders alongside Vault copies

desktop-app/README.md

@@ -34,6 +34,10 @@ Desktop-only files:
 - Document metadata loads at startup; Markdown content loads only when a document is opened and is kept in a bounded in-memory cache.
 - Native Markdown/HTML save and Markdown open flows use Neutralino dialogs and filesystem APIs.
 - A Markdown file passed as a launch argument is loaded into the editor.
+- Files opened from disk can remain linked to their original path. Workspace (Vault) copies are separate documents; converting a linked file to a copy leaves its source untouched.
+- Linked files keep an app-local draft, but write to the original only on Ctrl+S. Reopening the same path selects its existing document rather than making another copy.
+- **Link a Markdown folder** adds its Markdown files under Linked Locations. Files added or changed outside the app are detected while the desktop app is running; a locally edited draft is not silently overwritten by an external change.
+- Removing a link removes the app's reference, not the original file or folder. Native file drops are not covered by the linked-file flow in this build.
 - The app asks before closing the window.
 - Prepared desktop resources load dynamic libraries from local `/libs/...` paths after setup.
 - Private mode pauses document-state persistence for the current page session without deleting the vault, shows an active incognito status, and resets on reload or exit. **Reset workspace** permanently deletes documents, folders, review data, settings, Secret Workspace records, history, trash, and recovery journals after confirmation.
@@ -81,7 +85,7 @@ Seven self-contained executables are written to `desktop-app/dist/markdown-viewe
 | Token security | One-time |
 | Logging | Disabled |
 
-Native APIs are intentionally allowlisted: app exit, open/save dialogs, message boxes, external URL/folder open, tray setup, scoped file and folder operations, path lookup, and storage get/set/remove. Command execution is not part of the default allowlist.
+Native APIs are intentionally allowlisted: app exit, open/save/folder dialogs, message boxes, external URL/folder open, tray setup, scoped file and folder operations, filesystem watchers, path lookup, and storage get/set/remove. Command execution is not part of the default allowlist.
 
 ## Local Renderer Security
 

desktop-app/neutralino.config.json

@@ -18,6 +18,7 @@
   "nativeAllowList": [
     "app.exit",
     "os.showOpenDialog",
+    "os.showFolderDialog",
     "os.showSaveDialog",
     "os.showMessageBox",
     "os.getPath",
@@ -34,6 +35,9 @@
     "filesystem.copy",
     "filesystem.move",
     "filesystem.remove",
+    "filesystem.createWatcher",
+    "filesystem.removeWatcher",
+    "filesystem.getWatchers",
     "storage.setData",
     "storage.getData",
     "storage.getKeys",

desktop-app/resources/index.html

@@ -72,7 +72,9 @@ <h1 class="h4 mb-0">Markdown Viewer<span class="visually-hidden"> - Online Markd
                         </button>
                         <ul class="dropdown-menu app-command-menu header-command-menu header-new-menu" aria-labelledby="importDropdown">
                             <li><a class="dropdown-item app-menu-item" href="#" id="header-new-document"><i class="lucide lucide-file-plus-2" aria-hidden="true"></i><span class="app-menu-label">New document</span></a></li>
-                            <li><a class="dropdown-item app-menu-item" href="#" id="import-from-file"><i class="lucide lucide-upload" aria-hidden="true"></i><span class="app-menu-label">From files</span></a></li>
+                            <li><a class="dropdown-item app-menu-item" href="#" id="import-from-file"><i class="lucide lucide-files" aria-hidden="true"></i><span class="app-menu-label">Import copies</span></a></li>
+                            <li class="desktop-linked-command" hidden><a class="dropdown-item app-menu-item" href="#" id="link-from-file"><i class="lucide lucide-link-2" aria-hidden="true"></i><span class="app-menu-label">Link files…</span></a></li>
+                            <li class="desktop-linked-command" hidden><a class="dropdown-item app-menu-item" href="#" id="link-from-folder"><i class="lucide lucide-folder-open" aria-hidden="true"></i><span class="app-menu-label">Link folder…</span></a></li>
                             <li><a class="dropdown-item app-menu-item" href="#" id="import-from-github"><i class="bi bi-github" aria-hidden="true"></i><span class="app-menu-label">From GitHub</span></a></li>
                         </ul>
                     </div>
@@ -346,6 +348,12 @@ <h2 id="document-sidebar-title">Explorer</h2>
                 <button id="sidebar-new-folder" class="document-sidebar-icon-btn" type="button" aria-label="Create a folder" title="New folder">
                   <i class="lucide lucide-folder-plus" aria-hidden="true"></i>
                 </button>
+                <button id="sidebar-link-files" class="document-sidebar-icon-btn desktop-linked-command" type="button" aria-label="Link Markdown files" title="Link Markdown files" hidden>
+                  <i class="lucide lucide-link-2" aria-hidden="true"></i>
+                </button>
+                <button id="sidebar-link-folder" class="document-sidebar-icon-btn desktop-linked-command" type="button" aria-label="Link a Markdown folder" title="Link a Markdown folder" hidden>
+                    <i class="lucide lucide-folder-open" aria-hidden="true"></i>
+                </button>
                 <button id="sidebar-trash-button" class="document-sidebar-icon-btn" type="button" aria-label="Open Trash" title="Trash">
                   <i class="lucide lucide-trash-2" aria-hidden="true"></i>
                 </button>

desktop-app/resources/js/main.js

@@ -131,6 +131,14 @@ if (isNeutralinoRuntime()) {
     // TODO: Fix https://github.com/neutralinojs/neutralinojs/issues/615
     setTray();
   }
+
+  window.addEventListener('markdown-viewer:ready', function() {
+    if (typeof window.NL_START_LINKED_MONITORING === 'function') {
+      window.NL_START_LINKED_MONITORING().catch(function(error) {
+        console.warn('Linked source monitoring initialization failed:', error);
+      });
+    }
+  }, { once: true });
 }
 
 // Open file passed as command-line argument (e.g. when double-clicking a .md file)
@@ -146,12 +154,13 @@ if (isNeutralinoRuntime()) {
 
     window.NL_INITIAL_FILE_CONTENT = {
       name: fileName,
-      content: content
+      content: content,
+      sourcePath: filePath
     };
 
     // Callback hook in case script.js loaded first
     if (window.NL_IMPORT_EXTERNAL_FILE) {
-      window.NL_IMPORT_EXTERNAL_FILE(content, fileName);
+      window.NL_IMPORT_EXTERNAL_FILE(content, fileName, filePath);
     }
   } catch (e) {
     console.warn('Could not open initial file:', e);