[BUG] pptx: `set width` on a group silently scales height too (implicit aspect-ratio lock, no opt-out)

[jasonwei1002]

Summary

set on a group silently locks the aspect ratio: setting only width also scales height (and vice versa). There is no way at L2 to resize a group along a single axis; the only workaround is raw-set on p:grpSpPr/a:xfrm/a:ext.

Repro (v1.0.136)

officecli create g.pptx
officecli add g.pptx / --type slide
officecli add g.pptx '/slide[1]' --type shape --prop geometry=rect --prop x=2cm --prop y=2cm --prop width=4cm --prop height=2cm
officecli add g.pptx '/slide[1]' --type shape --prop geometry=rect --prop x=8cm --prop y=5cm --prop width=4cm --prop height=2cm
officecli add g.pptx '/slide[1]' --type group --prop shapes=1,2
officecli get g.pptx '/slide[1]/group[1]'
# -> x=2cm y=2cm width=10cm height=5cm

officecli set g.pptx '/slide[1]/group[1]' --prop x=1cm --prop width=12cm
officecli get g.pptx '/slide[1]/group[1]'
# -> width=12cm height=6cm   <-- height changed from 5cm to 6cm, was never requested

Expected

set width on a group should change only ext.cx (children scale horizontally via the chExt mapping), matching the behavior of set width on a plain shape. If the aspect lock is intentional, it should be opt-in (e.g. --prop keepAspect=true) and the default should honor exactly the properties the caller passed.

Workaround for others hitting this

officecli raw-set deck.pptx ppt/slides/slideN.xml \
  --xpath "//p:grpSp[...]/p:grpSpPr/a:xfrm/a:ext" \
  --action setattr --xml 'cy=<original EMU>'

[goworm]

Confirmed — the implicit aspect lock was intentional (it protected add --type diagram groups from single-axis squashing) but leaking it onto every group with no opt-out was wrong. Fixed on main (45e432b), will be in the next release:

• set on a group now changes exactly the axes you pass — --prop width=12cm leaves height untouched (children still scale horizontally via the chExt baseline). Same fix applied to docx groups.
• The proportional behavior is now opt-in: --prop width=12cm --prop keepAspect=true scales height by the same ratio and re-bakes child font sizes with the uniform resize.

Verified against your repro:

officecli set g.pptx '/slide[1]/group[1]' --prop x=1cm --prop width=12cm
officecli get g.pptx '/slide[1]/group[1]'
# -> x=1cm width=12cm height=5cm        (height untouched)

officecli set g.pptx '/slide[1]/group[1]' --prop width=6cm --prop keepAspect=true
# -> width=6cm height=2.5cm             (opt-in proportional)

Thanks for the precise repro and the raw-set workaround for others in the meantime.