Unconventional keymaps
In unreleased commits 31f3810 and dd82c96 the keymappings for PrevWeek/NextWeek were changed from </> to k/up-arrow and j/down-arrow. This is quite unusual, as the j/k keybindings are a vi-style convention for line-down and line-up, but tz is using them like ‘page down’ and ‘page up’ vertical motions (ctrl-f/shift-down, and ctrl-b/shift-up and in vi). Furthermore, since the tz timeline is horizontal, it makes more sense that prev week and next week would be horizontal motions.
Therefore, I think it would make more sense to (a) use the horizontal motions and shift-arrow for day movements, and (b) support page up/page down keys (not line up/down) if the ‘page’ concept is desired for tz. Another advantage is that ctrl-arrow and shift-page could then be used for the week motions, and ctrl-shift-* could be used for month motions.
Edit: As an afterthought, although the convention is ctrl-b/ctrl-f (full-screen backward/forward) for page up/page down in vi, it maybe a good mnemonic to map vi’s ctrl-u/ctrl-d (half-screen scroll up/scroll down) for day navigation in tz, and map ctrl-b/ctrl-f for week navigation.