Root cause: body is user-select: none and each feature had to opt back in; the Markdown preview (and other read-only views) never did, and the app-wide contextmenu guard left no Copy item.
Fix: shared selectableText class (src/ui) for read-only content, and a fallback Copy context menu from browserGuards when right-clicking a selection or a selectable area (component menus still win).
Siblings covered: Quick Documentation / hover / completion docs, hover errors, Quick Definition, debugger value tooltip, inspection messages, message dialogs (no drag on body text), notification titles, About dialog; existing selectable consoles now get Copy too.
Verified in-app on macOS: select in Markdown preview, right-click Copy puts the text on the clipboard; tab context menu unchanged.
Claude-Session: https://claude.ai/code/session_01VUYsdXA2nkF5v6zsC93dpn
Right-clicks the app doesn't handle itself, such as on code-lens or inlay
widgets inside the editor or in text fields, fell through to WebKit's own
menu, whose Reload item reloads the whole app. Block it everywhere; the
app's own menus already call preventDefault before this guard runs.
Claude-Session: https://claude.ai/code/session_01B65qLEKnkeYTGdbwhLpjCu
l0ng-ai