fix: v0.10.2 drag-select stays highlighted and copies

A left drag in the pane is turned into xterm's own selection (as Shift+drag
does) instead of tmux copy-mode, which dropped the highlight on release.
Copy on release with a toast; Ctrl+C copies when something is selected.
Wheel scroll and status-line clicks still reach tmux. Closes #51

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WHRLCCdXYm41Qx5kNhehaP

web/src/term.js

@@ -90,7 +90,7 @@ export async function loadFonts(size) {
   }
 }
 
-export function createTerminal(container, { fontSize, theme = 'dark', onShiftEnter }) {
+export function createTerminal(container, { fontSize, theme = 'dark', onShiftEnter, onCopied }) {
   const term = new Terminal({
     fontFamily: FONT_FAMILY,
     fontSize,
@@ -113,16 +113,28 @@ export function createTerminal(container, { fontSize, theme = 'dark', onShiftEnt
     window.open(uri, '_blank', 'noopener');
   }));
 
+  const copySelection = () => {
+    const text = term.getSelection();
+    navigator.clipboard?.writeText(text).then(() => onCopied?.(text), () => {});
+  };
+
   term.attachCustomKeyEventHandler((event) => {
     // Shift+Enter: newline in Claude's prompt (Ctrl+J), not submit.
     if (event.key === 'Enter' && event.shiftKey && !event.ctrlKey && !event.altKey && !event.metaKey) {
       if (event.type === 'keydown') onShiftEnter();
       return false;
     }
+    // Ctrl+C with text selected copies it instead of interrupting (devdesk#51).
+    if (event.type === 'keydown' && event.ctrlKey && !event.shiftKey && !event.altKey && !event.metaKey
+        && event.code === 'KeyC' && term.hasSelection()) {
+      copySelection();
+      term.clearSelection();
+      return false;
+    }
     // Ctrl+Shift+C / Ctrl+Shift+V: browser clipboard, like desktop terminals.
     if (event.type === 'keydown' && event.ctrlKey && event.shiftKey && !event.altKey) {
       if (event.code === 'KeyC' && term.hasSelection()) {
-        navigator.clipboard?.writeText(term.getSelection()).catch(() => {});
+        copySelection();
         return false;
       }
       if (event.code === 'KeyV') {
@@ -135,6 +147,35 @@ export function createTerminal(container, { fontSize, theme = 'dark', onShiftEnt
 
   term.open(container);
 
+  // devdesk#51: tmux runs with the mouse on (wheel scrolls its history), so a
+  // drag would select inside tmux, which copies and then drops the highlight on
+  // release. A left-button drag in the terminal is made a browser selection
+  // instead (what Shift+drag does): it stays highlighted and is copied on
+  // release. Clicks on tmux's status line (the window tabs) still go to tmux.
+  const screen = () => container.querySelector('.xterm-screen');
+  container.addEventListener('mousedown', (event) => {
+    if (event.button !== 0 || event.shiftKey || event.ddForced || term.modes.mouseTrackingMode === 'none') return;
+    const rect = screen()?.getBoundingClientRect();
+    if (!rect) return;
+    const row = Math.floor(((event.clientY - rect.top) / rect.height) * term.rows);
+    if (row >= term.rows - 1) return; // status line
+    event.preventDefault();
+    event.stopImmediatePropagation();
+    const forced = new MouseEvent('mousedown', {
+      bubbles: true, cancelable: true, view: window, detail: event.detail, button: 0, buttons: event.buttons,
+      clientX: event.clientX, clientY: event.clientY, screenX: event.screenX, screenY: event.screenY,
+      shiftKey: true, ctrlKey: event.ctrlKey, altKey: event.altKey, metaKey: event.metaKey,
+    });
+    forced.ddForced = true;
+    event.target.dispatchEvent(forced);
+  }, true);
+  // Copy when the drag (or double/triple click) ends with something selected.
+  container.addEventListener('mouseup', () => {
+    setTimeout(() => {
+      if (term.hasSelection() && term.getSelection().trim()) copySelection();
+    }, 0);
+  });
+
   // Touch devices: the DOM renderer is more reliable at high DPR than WebGL.
   if (window.matchMedia?.('(pointer: coarse)').matches) return { term, fit };
   try {