test(mdviewer): add LRU cache test for files removed from working set

- Verify files closed from working set move to LRU cache (not evicted)
- Expose __getWorkingSetPaths test helper for verifying working set state
- 24/24 md editor integration tests passing

Author: abose

src-mdviewer/src/bridge.js

@@ -116,6 +116,9 @@ export function initBridge() {
     window.__getCacheKeys = function () {
         return docCache._getCacheKeysForTest();
     };
+    window.__getWorkingSetPaths = function () {
+        return docCache._getWorkingSetPathsForTest();
+    };
     window.__triggerContentSync = function () {
         const content = document.getElementById("viewer-content");
         if (content) {

src-mdviewer/src/core/doc-cache.js

@@ -48,6 +48,11 @@ export function _getCacheKeysForTest() {
     return Array.from(cache.keys());
 }
 
+/** For test access only — returns the working set paths. */
+export function _getWorkingSetPathsForTest() {
+    return Array.from(workingSetPaths);
+}
+
 /**
  * Get the currently active file path.
  */

test/spec/md-editor-integ-test.js

@@ -907,6 +907,47 @@ define(function (require, exports, module) {
                 expect(keys.some(k => k.endsWith("doc2.md"))).toBeTrue();
                 expect(keys.some(k => k.endsWith("doc3.md"))).toBeTrue();
             }, 15000);
+
+            it("should files removed from working set move to LRU cache (not evicted)", async function () {
+                const win = _getMdIFrameWin();
+
+                // Open doc1 and doc2 to put them in cache and working set
+                await _openMdFileAndWaitForPreview("doc1.md");
+                await awaitsFor(() => _getViewerH1Text().includes("Document One"),
+                    "doc1 to load");
+
+                await _openMdFileAndWaitForPreview("doc2.md");
+                await awaitsFor(() => _getViewerH1Text().includes("Document Two"),
+                    "doc2 to load");
+
+                // Both should be in cache and working set
+                await awaitsFor(() => {
+                    const cacheKeys = win.__getCacheKeys();
+                    const wsPaths = win.__getWorkingSetPaths();
+                    return cacheKeys.some(k => k.endsWith("doc1.md")) &&
+                        cacheKeys.some(k => k.endsWith("doc2.md")) &&
+                        wsPaths.some(p => p.endsWith("doc1.md")) &&
+                        wsPaths.some(p => p.endsWith("doc2.md"));
+                }, "doc1 and doc2 in cache and working set");
+
+                // Close doc2 from working set
+                await awaitsForDone(CommandManager.execute(Commands.FILE_CLOSE),
+                    "close doc2");
+
+                // doc2 should still be in cache (moved to LRU) but not in working set
+                await awaitsFor(() => {
+                    const cacheKeys = win.__getCacheKeys();
+                    const wsPaths = win.__getWorkingSetPaths();
+                    return cacheKeys.some(k => k.endsWith("doc2.md")) &&
+                        !wsPaths.some(p => p.endsWith("doc2.md"));
+                }, "doc2 in cache (LRU) but not in working set");
+
+                // doc1 should still be in both cache and working set
+                const cacheKeys = win.__getCacheKeys();
+                const wsPaths = win.__getWorkingSetPaths();
+                expect(cacheKeys.some(k => k.endsWith("doc1.md"))).toBeTrue();
+                expect(wsPaths.some(p => p.endsWith("doc1.md"))).toBeTrue();
+            }, 15000);
         });
 
     });