When a debugged step panicked, the nested execute rolled the run back and dropped the debugger
before advance could reattach the machine, so the caller got "No macro is being debugged"
instead of the failed step. For example, stepping into a step whose command panics lost the
step path and the panic message. advance now sees that the run was already rolled back and
returns the usual failed result with the step error.
macro.debug runs a macro one step at a time. start checks the macro as
macro.run does (policy, approval, inputs, footprint and output rule)
and pauses before the first step; step runs one step; continue runs to
the next breakpoint; runTo runs to a chosen step path, stopping at
breakpoints on the way; stop ends the run and keeps its changes or
rolls them back; state reports where it is. Breakpoints are the steps'
own flags plus a list of paths given with any action (breakpointsOnly
makes the list replace the flags), and they stop in every pass of a
Repeat.
The run lives on the session between calls, inside an undo group that
spans them (group_begin and group_end), so a debugged run is one undo
step "Run Macro: <name>", as a normal run is. A failing step ends the
run and rolls it back; so does a Stop step that asks for a rollback.
While a macro is being debugged, edits of the workbooks the run touched
(its own, and any other a step changed) are refused at the top level
with "Finish or stop the macro first"; other workbooks stay editable,
and selecting and queries still work. Every answer gives the next
step's path, kind, command, parameters as they would run now (tokens
resolved), the Repeat pass, the parameters of the step that just ran,
the steps executed and the cells changed so far. Each action gets its
own time limit.
If a command panics while a step runs, the session's panic guard rolls
the debugged run back as well, so its undo group never stays open.
prxnvt