cl-debugger-hook: mutable global (fn (c hook) result); cl-invoke-debugger
calls it with infinite-recursion guard (sets hook nil during call).
cl-error now routes unhandled errors through cl-invoke-debugger instead of
bare host error — allows the hook to invoke a restart and resume.
cl-break-on-signals: when set to a type name, cl-signal fires the debugger
hook before walking handlers if the condition matches.
cl-invoke-restart-interactively: calls the restart fn with no args (no
terminal protocol — equivalent to (invoke-restart name)).
4 new tests in conditions.sx covering all three; Phase 3 fully complete.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
giles
733b1ebefa