When the user shrinks the terminal window small enough that nvim
can't fit all splits (including our two bars + dapui panes + source),
nvim closes some windows to make room. winfixheight prevents resize
but doesn't prevent close. When the user expands again, the closed
bars don't come back automatically — the layout is permanently
broken until debug mode is toggled.
Fix: on VimResized (deferred via vim.schedule), check if sbar_win
and cbar_win are still valid. If either got killed, clear the
stale reference and call open_bars() which idempotently recreates
anything missing. Then re-pin dapui sizes to restore the intended
layout.
WinResized autocmd retained for intra-session drift (mouse-drag
resizes, plugin-driven wincmd=).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>