fix(mdviewer): scroll restore, format bar in code blocks, test stability

- Fix scroll position not restored after reload: send MDVIEWR_SOURCE_LINES
  only after edit-mode content changes, not during initial load/reload
  where it would cause reflows that reset scroll position
- Force light theme via no-op handleSetTheme (HTML default is light)
- Hide format bar when selection is inside code blocks
- Add beforeEach cleanup in Document Cache test suite to prevent state
  leakage between scroll position tests

Author: abose

src-mdviewer/src/bridge.js

@@ -800,15 +800,11 @@ function handleReloadFile(data) {
 
 // --- Theme, edit mode, locale ---
 
-function handleSetTheme(data) {
+function handleSetTheme(_data) {
     // Force light theme for a paper-like appearance regardless of editor theme.
     // The theme infrastructure is preserved for future use.
-    const appliedTheme = "light";
-    // Skip if already applied to avoid reflows that can reset scroll position
-    if (document.documentElement.getAttribute("data-theme") === appliedTheme) return;
-    document.documentElement.setAttribute("data-theme", appliedTheme);
-    document.documentElement.style.colorScheme = "light";
-    setState({ theme: appliedTheme });
+    // Theme is set in index.html (data-theme="light") so no action needed here.
+    // Avoid setting attributes/styles to prevent reflows that reset scroll position.
 }
 
 function handleSetEditMode(data) {

src-mdviewer/src/components/format-bar.js

@@ -224,6 +224,13 @@ function updatePosition() {
       hide();
       return;
     }
+    // Skip if selection is inside a code block — formatting doesn't apply
+    const anchorEl = sel.anchorNode.nodeType === Node.ELEMENT_NODE
+      ? sel.anchorNode : sel.anchorNode.parentElement;
+    if (anchorEl && anchorEl.closest("pre")) {
+      hide();
+      return;
+    }
     // Require some meaningful selection length
     const text = sel.toString();
     if (text.length < 2) {

src/extensionsIntegrated/Phoenix-live-preview/MarkdownSync.js

@@ -358,17 +358,12 @@ define(function (require, exports, module) {
             return;
         }
 
-        const mdText = _doc.getText();
         iframeWindow.postMessage({
             type: "MDVIEWR_SWITCH_FILE",
-            markdown: mdText,
+            markdown: _doc.getText(),
             baseURL: _baseURL,
             filePath: _doc.file.fullPath
         }, "*");
-        iframeWindow.postMessage({
-            type: "MDVIEWR_SOURCE_LINES",
-            markdown: mdText
-        }, "*");
     }
 
     function _sendContent() {
@@ -380,19 +375,12 @@ define(function (require, exports, module) {
             return;
         }
 
-        const mdText = _doc.getText();
         iframeWindow.postMessage({
             type: "MDVIEWR_SET_CONTENT",
-            markdown: mdText,
+            markdown: _doc.getText(),
             baseURL: _baseURL,
             filePath: _doc.file.fullPath
         }, "*");
-        // Send source line mapping so the iframe can annotate sub-element
-        // lines (e.g. <br> within paragraphs) on first load.
-        iframeWindow.postMessage({
-            type: "MDVIEWR_SOURCE_LINES",
-            markdown: mdText
-        }, "*");
     }
 
     function _sendUpdate(changeOrigin) {

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

@@ -18,7 +18,7 @@
  *
  */
 
-/*global describe, beforeAll, afterAll, awaitsFor, it, awaitsForDone, expect, awaits*/
+/*global describe, beforeAll, beforeEach, afterAll, awaitsFor, it, awaitsForDone, expect, awaits*/
 
 define(function (require, exports, module) {
 
@@ -629,6 +629,13 @@ define(function (require, exports, module) {
                 }
             }, 30000);
 
+            beforeEach(async function () {
+                // Reset scroll and close files between tests to prevent state leakage
+                _setViewerScrollTop(0);
+                await awaitsForDone(CommandManager.execute(Commands.FILE_CLOSE_ALL, { _forceClose: true }),
+                    "close all between cache tests");
+            }, 10000);
+
             it("should switch between MD files with viewer showing correct content", async function () {
                 await _openMdFileAndWaitForPreview("doc1.md");
                 await awaitsFor(() => _getViewerH1Text().includes("Document One"),