Block major-mode changes in live ghostel buffers#544
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Changing the major mode runs kill-all-local-variables, which wipes the buffer-locals the native module and PTY depend on, leaving a broken buffer (vterm guards this too, citing segfaults). Signal a user-error from change-major-mode-hook while the terminal process is live; the hook runs before any local state is destroyed, so the aborted switch leaves the buffer fully functional. Dead-process buffers may still change mode freely, which ghostel-compile's finalize/recompile flow relies on.
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Changing the major mode in a ghostel buffer runs
kill-all-local-variables, which wipes the buffer-locals the native module and PTY depend on, leaving a broken buffer. vterm guards against the same thing, citing segfaults.ghostel-modenow adds a buffer-localchange-major-mode-hookthat signals auser-errorwhile the terminal process is live. The hook runs as the first statement ofkill-all-local-variables, before any local state is destroyed, so the aborted switch leaves the buffer fully functional.The guard is conditional on
(process-live-p ghostel--process)rather than unconditional because ghostel-compile legitimately switches modes in both directions (ghostel-mode→ghostel-compile-view-modeat finalize, and back on recompile) — always after tearing down the terminal, so those flows pass through untouched.Verified in a live session: programmatic and interactive mode changes are blocked in a running terminal (which keeps working afterwards), ghostel-compile finalize and
grecompile are unaffected, and mode changes succeed once the shell exits.