fix(mdviewer): run renderAfterHTML on first load for code block sync

Call renderAfterHTML after createEntry and on cache-hit-unchanged
switch so Prism highlighting and per-line source annotations run on
first document load, not just on subsequent morphdom updates. Adds
stronger cursor-sync highlight for code blocks where the dark
background makes the default too faint.

Author: abose

src-mdviewer/src/bridge.js

@@ -9,6 +9,7 @@ import { setLocale } from "./core/i18n.js";
 import { marked } from "marked";
 import * as docCache from "./core/doc-cache.js";
 import { broadcastSelectionStateSync } from "./components/editor.js";
+import { renderAfterHTML } from "./components/viewer.js";
 
 let _syncId = 0;
 let _lastReceivedSyncId = -1;
@@ -571,6 +572,12 @@ function handleSetContent(data) {
         docCache.switchTo(filePath);
     }
 
+    // Run post-render processing (Prism highlighting, code block line annotation)
+    const content = document.getElementById("viewer-content");
+    if (content) {
+        renderAfterHTML(content, parseResult);
+    }
+
     setState({
         currentContent: markdown,
         parseResult: parseResult
@@ -668,6 +675,13 @@ function handleSwitchFile(data) {
         // Cache hit, content unchanged — instant switch
         docCache.switchTo(filePath);
 
+        // Ensure code blocks are highlighted and line-annotated (may be missing on first load)
+        const cachedContent = document.getElementById("viewer-content");
+        if (cachedContent && !cachedContent.querySelector("pre code span[data-source-line]") &&
+            cachedContent.querySelector("pre[data-source-line]")) {
+            renderAfterHTML(cachedContent, existing.parseResult);
+        }
+
         setState({
             currentContent: markdown,
             parseResult: existing.parseResult
@@ -692,6 +706,12 @@ function handleSwitchFile(data) {
         docCache.createEntry(filePath, markdown, parseResult);
         docCache.switchTo(filePath);
 
+        // Run post-render processing on newly created entry
+        const newContent = document.getElementById("viewer-content");
+        if (newContent) {
+            renderAfterHTML(newContent, parseResult);
+        }
+
         // Restore scroll position and edit mode from reload if applicable
         if (_pendingReloadScroll && _pendingReloadScroll.filePath === filePath) {
             const entry = docCache.getEntry(filePath);

src-mdviewer/src/styles/markdown.css

@@ -484,6 +484,15 @@
   background-color: rgba(50, 100, 220, 0.14);
 }
 
+/* Stronger highlight inside code blocks (dark bg makes the default too faint) */
+pre .cursor-sync-highlight {
+  background-color: rgba(100, 150, 255, 0.25);
+}
+
+[data-theme="light"] pre .cursor-sync-highlight {
+  background-color: rgba(50, 100, 220, 0.18);
+}
+
 /* ===== Mermaid diagrams ===== */
 
 .mermaid-diagram {