feat: add copy-to-clipboard button on code blocks in viewer + popout

- CSS: .code-block-wrapper with relative positioning
- CSS: .copy-code-btn with hover opacity transition (hidden until hover)
- CSS: .copied state (green accent) after successful copy
- viewer.js: wraps each <pre> in .code-block-wrapper + appends copy button
- popout.html: same logic with vanilla JS (ES5 compatible)
- Button: 'Copier' → '✓ Copié' on click, reverts after 2s
- Toast: showToast('Code copié dans le presse-papiers') via navigator.clipboard

frontend/js/viewer.js

@@ -672,6 +672,31 @@ export function renderFile(data) {
     safeHighlight(block);
   });
 
+  // Add copy buttons to code blocks
+  area.querySelectorAll("pre").forEach((pre) => {
+    if (pre.parentElement?.classList.contains("code-block-wrapper")) return;
+    const wrapper = el("div", { class: "code-block-wrapper" }, []);
+    wrapper.style.position = "relative";
+    pre.replaceWith(wrapper);
+    wrapper.appendChild(pre);
+
+    const btn = el("button", { class: "copy-code-btn", title: "Copier le code" }, [document.createTextNode("Copier")]);
+    btn.addEventListener("click", async (e) => {
+      e.stopPropagation();
+      const code = pre.querySelector("code")?.textContent || pre.textContent;
+      try {
+        await navigator.clipboard.writeText(code);
+        btn.textContent = "✓ Copié";
+        btn.classList.add("copied");
+        if (typeof showToast === "function") showToast("Code copié dans le presse-papiers", "success");
+        setTimeout(() => { btn.textContent = "Copier"; btn.classList.remove("copied"); }, 2000);
+      } catch {
+        if (typeof showToast === "function") showToast("Erreur lors de la copie", "error");
+      }
+    });
+    wrapper.appendChild(btn);
+  });
+
   // Render Mermaid diagrams
   renderMermaidBlocks(area);
 

frontend/popout.html

@@ -893,24 +893,47 @@ const RightSidebarManager = {
         OutlineManager.init(); RightSidebarManager.init();
 
         // Mermaid + code highlighting handled below FIRST (before highlight.js)
+        function highlightCode() {
+          document.querySelectorAll('pre code:not(.language-mermaid)').forEach((el) => {
+            if (typeof hljs !== 'undefined') hljs.highlightElement(el);
+          });
+        }
+        function addCopyButtons() {
+          document.querySelectorAll('pre').forEach((pre) => {
+            if (pre.parentElement && pre.parentElement.classList.contains('code-block-wrapper')) return;
+            var wrapper = document.createElement('div');
+            wrapper.className = 'code-block-wrapper';
+            wrapper.style.position = 'relative';
+            pre.replaceWith(wrapper);
+            wrapper.appendChild(pre);
+            var btn = document.createElement('button');
+            btn.className = 'copy-code-btn';
+            btn.title = 'Copier le code';
+            btn.textContent = 'Copier';
+            btn.addEventListener('click', function(e) {
+              e.stopPropagation();
+              var code = (pre.querySelector('code') || pre).textContent;
+              navigator.clipboard.writeText(code).then(function() {
+                btn.textContent = '✓ Copié';
+                btn.classList.add('copied');
+                setTimeout(function() { btn.textContent = 'Copier'; btn.classList.remove('copied'); }, 2000);
+              }).catch(function() {});
+            });
+            wrapper.appendChild(btn);
+          });
+        }
         if (typeof mermaid !== 'undefined') {
           mermaid.initialize({ startOnLoad: false, theme: document.documentElement.getAttribute('data-theme') === 'dark' ? 'dark' : 'default' });
           mermaid.run({ querySelector: '.language-mermaid' }).then(() => {
-            // After Mermaid renders, highlight remaining code blocks (skip mermaid SVGs)
-            document.querySelectorAll('pre code:not(.language-mermaid)').forEach((el) => {
-              if (typeof hljs !== 'undefined') hljs.highlightElement(el);
-            });
+            highlightCode();
+            addCopyButtons();
           }).catch(() => {
-            // Mermaid failed — highlight everything else anyway
-            document.querySelectorAll('pre code:not(.language-mermaid)').forEach((el) => {
-              if (typeof hljs !== 'undefined') hljs.highlightElement(el);
-            });
+            highlightCode();
+            addCopyButtons();
           });
         } else {
-          // No mermaid — just highlight code
-          document.querySelectorAll('pre code').forEach((el) => {
-            if (typeof hljs !== 'undefined') hljs.highlightElement(el);
-          });
+          highlightCode();
+          addCopyButtons();
         }
 
         // Hide loading

frontend/style.css

@@ -8528,3 +8528,35 @@ body.popup-mode .content-area {
 .pane-resize-handle:hover {
   background: var(--accent);
 }
+.code-block-wrapper:hover .copy-code-btn {
+  opacity: 1;
+}
+.copy-code-btn {
+  position: absolute;
+  top: 8px;
+  right: 8px;
+  display: flex;
+  align-items: center;
+  gap: 4px;
+  padding: 4px 10px;
+  background: var(--bg-secondary);
+  border: 1px solid var(--border);
+  border-radius: var(--radius);
+  color: var(--text-secondary);
+  font-size: 11px;
+  font-family: var(--mono);
+  cursor: pointer;
+  opacity: 0;
+  transition: opacity 150ms ease, background 150ms ease, color 150ms ease;
+  z-index: 5;
+}
+.copy-code-btn:hover {
+  background: var(--accent);
+  color: #fff;
+  border-color: var(--accent);
+}
+.copy-code-btn.copied {
+  background: var(--accent-green);
+  color: #fff;
+  border-color: var(--accent-green);
+}