feat(gui): add document-origin tracking and display in window title (#16)

- Add originForDocument(), setDocumentOrigin(), clearDocumentOrigin()
  methods to OriginManager
- Add signalDocumentOriginChanged signal for UI updates
- Add document-to-origin tracking map in OriginManager
- Update MDIView::buildWindowTitle() to append origin suffix for
  non-local origins (e.g., 'Part001 [Silo]')

This implements Issue #16: Document origin tracking and display

src/Gui/MDIView.cpp

@@ -44,7 +44,9 @@
 #include "Application.h"
 #include "Document.h"
 #include "FileDialog.h"
+#include "FileOrigin.h"
 #include "MainWindow.h"
+#include "OriginManager.h"
 #include "ViewProviderDocumentObject.h"
 
 
@@ -522,6 +524,13 @@ QString MDIView::buildWindowTitle() const
     QString windowTitle;
     if (auto document = getAppDocument()) {
         windowTitle.append(QString::fromStdString(document->Label.getStrValue()));
+
+        // Append origin suffix for non-local origins
+        FileOrigin* origin = OriginManager::instance()->originForDocument(document);
+        if (origin && origin->type() != OriginType::Local) {
+            windowTitle.append(QStringLiteral(" [%1]")
+                .arg(QString::fromStdString(origin->nickname())));
+        }
     }
 
     return windowTitle;

src/Gui/OriginManager.cpp

@@ -231,6 +231,63 @@ FileOrigin* OriginManager::findOwningOrigin(App::Document* doc) const
     return nullptr;
 }
 
+FileOrigin* OriginManager::originForDocument(App::Document* doc) const
+{
+    if (!doc) {
+        return nullptr;
+    }
+
+    // Check explicit association first
+    auto it = _documentOrigins.find(doc);
+    if (it != _documentOrigins.end()) {
+        FileOrigin* origin = getOrigin(it->second);
+        if (origin) {
+            return origin;
+        }
+        // Origin was unregistered, clear stale association
+        _documentOrigins.erase(it);
+    }
+
+    // Fall back to ownership detection
+    FileOrigin* owner = findOwningOrigin(doc);
+    if (owner) {
+        // Cache the result
+        _documentOrigins[doc] = owner->id();
+        return owner;
+    }
+
+    return nullptr;
+}
+
+void OriginManager::setDocumentOrigin(App::Document* doc, FileOrigin* origin)
+{
+    if (!doc) {
+        return;
+    }
+
+    std::string originId = origin ? origin->id() : "";
+
+    if (origin) {
+        _documentOrigins[doc] = originId;
+    } else {
+        _documentOrigins.erase(doc);
+    }
+
+    signalDocumentOriginChanged(doc, originId);
+}
+
+void OriginManager::clearDocumentOrigin(App::Document* doc)
+{
+    if (!doc) {
+        return;
+    }
+
+    auto it = _documentOrigins.find(doc);
+    if (it != _documentOrigins.end()) {
+        _documentOrigins.erase(it);
+    }
+}
+
 FileOrigin* OriginManager::originForNewDocument() const
 {
     return currentOrigin();

src/Gui/OriginManager.h

@@ -121,6 +121,27 @@ public:
      */
     FileOrigin* findOwningOrigin(App::Document* doc) const;
 
+    /**
+     * Get the origin associated with a document.
+     * First checks explicit association, then uses findOwningOrigin().
+     * @param doc The document to check
+     * @return The document's origin or nullptr if unknown
+     */
+    FileOrigin* originForDocument(App::Document* doc) const;
+
+    /**
+     * Associate a document with an origin.
+     * @param doc The document
+     * @param origin The origin to associate (nullptr to clear)
+     */
+    void setDocumentOrigin(App::Document* doc, FileOrigin* origin);
+
+    /**
+     * Clear document origin association (called when document closes).
+     * @param doc The document being closed
+     */
+    void clearDocumentOrigin(App::Document* doc);
+
     /**
      * Get the appropriate origin for a new document.
      * Returns the current origin.
@@ -137,6 +158,8 @@ public:
     fastsignals::signal<void(const std::string&)> signalOriginUnregistered;
     /** Emitted when current origin changes */
     fastsignals::signal<void(const std::string&)> signalCurrentOriginChanged;
+    /** Emitted when a document's origin association changes */
+    fastsignals::signal<void(App::Document*, const std::string&)> signalDocumentOriginChanged;
     //@}
 
 protected:
@@ -151,6 +174,9 @@ private:
     static OriginManager* _instance;
     std::map<std::string, std::unique_ptr<FileOrigin>> _origins;
     std::string _currentOriginId;
+
+    // Document-to-origin associations (doc -> origin ID)
+    mutable std::map<App::Document*, std::string> _documentOrigins;
 };
 
 }  // namespace Gui