How can we design addons for couchcms, I would like to contribute.
Thank you and you are welcome to contribute (as is everybody).
In terms of addons, Couch (currently) allows creating the following -
Custom tags (e.g. <cms:your_tag> to use in templates)
Custom fields (i.e. editable regions displayed in the admin-panel e.g. <cms:editable type='your_region_type'>)
Custom form fields (i.e. inputs used in front-end forms e.g. <cms:input type='your_input_type' />)
As a matter of fact, beginning with v1.3 all the new features added to Couch have been implemented as 'addons' using the custom types mentioned above.
For example, the 'repeatable-regions', 'relations', 'data-bound forms' etc. are all addons.
Couch advertises itself as a "designer's CMS" so I have not (yet) put up any documentation explaining how to implement these types (except shortcodes) as that would involve raw PHP coding.
However, for those who want to do it, the process is pretty straightforward.
If you could download the v1.4RC (viewtopic.php?f=5&t=7713), all the scripts contained within the 'addons' folder can serve as a guide.
I have put in some comments in 'couch/field.php' file above 'class KUserDefinedField' (the base class for creating custom fields) - you might find those also useful.
Finally, please feel free to let me know if you find something confusing.
I'll be only happy to assist.