[Bug] Achordion disables RETRO_TAPPING

[wolfwood]

Describe the bug

Single mod-tap key holds don't produce the tap key, with RETRO_TAPPING, when Achordion is enabled.

I'm using a new keyboard, which I am much slower to type on. I have previously used Homerow mods quite happily on both QMK and ZMK.

I noticed after enabling homerow mods, eg LALT_T(KC_A), that my normal tapping strokes on the home row weren't reliably producing keystrokes anymore. I read up on QMK's tap-hold implementation and learned that by default mod-tap holds do not register if no second key is pressed. I assumed I was simply holding too long and that was swallowing my keystrokes. RETRO_TAPPING to the rescue. This did what it said and transmitted my tap keys when holds were released, provided no other key was pressed.

However, then I enabled Achordion, and the missing keystrokes on single mod-tap holds returned.

Information

Do the keys involved use any of the following features?

• Achordion (from this repo)
• Auto Shift
• Combos
• Key Overrides
• Mod-tap or Layer-tap keys
• Other custom userspace code:

[NikGovorov]

From https://getreuer.info/posts/keyboards/achordion/index.html:
Additionally, RETRO_TAP and RETRO_SHIFT aren’t supported. It looks possible, but I haven’t yet implemented them.

[NikGovorov]

Have you tried to increase tapping term?

[akaralar]

I have the same problem. I'm using Retro Tapping for a single key and the key does not register as a tap unless released after Achordion timeout. I saw the blog post says it isn't supported but it also says it should be possible to implement. I checked the code and changing

if (achordion_state == STATE_HOLDING) {

to

if (achordion_state == STATE_HOLDING || IS_RETRO(tap_hold_keycode)) {

on line 135 seems to have fixed it for me. I'm not sure if I'm considering every edge case though, if @getreuer would be so kind to provide some feedback whether it's a viable workaround would be great!

[akaralar]

@wolfwood just so you know I opened (#55) for this if you'd like to try it out. It fixed retro tap keys for me, if you try let me know if it also fixes it for you

[wolfwood]

@akaralar I saw your earlier message about cancelling correct achordion behavior. did you change something to address that?

[akaralar]

@wolfwood it turned out to be unrelated to what I did, as when I took my changes back the issue was still happening, hence I deleted that message. I can't say I know all the bells and whistles of QMK but the plumbing we do takes place after a tap&hold key is released, not sure if things can go very wrong there for Achordion functionality as we have already released the key. When the repo owner checks the code I can say that with more confidence but so far it's working fine for me with Achordion.