Calisthenics aren't going to build a lot of muscle. Cardio in general if you're a lean person isn't going to do much for you. Strength training either with weights or just body weight should you gain muscle.
I'm at a healthy weight at the moment (5'11" 150 lbs, pretty low BF%) and could definitely stand to gain more muscle. I've been doing various calisthenics/bodyweight exercises 3-4 times a week, all while eating mostly primal. I've definitely noticed it's been hard to gain weight, as I think I've been going in and out of ketosis the last few months. Workout days I might get 100-200g of carbs in the day, and non-workout days it's often under 50. I have made minimal gains, albeit slowly. But I've stayed lean the entire time, so that's been nice.
While I know this isn't the most efficient way to get fit, is there anything wrong with what I'm doing? It almost seems like I'm doing something similar to the TKD (targeted ketogenic diet), which AFAIK doesn't say much about muscle growth but focuses more on purely energy for workouts, and fat loss.
Calisthenics aren't going to build a lot of muscle. Cardio in general if you're a lean person isn't going to do much for you. Strength training either with weights or just body weight should you gain muscle.
You can definitely stand to eat more carbs, and reduce fat a little (so as to not over-eat from all angles) try to up them to 300 or so on workout days and keep them around 100 on non-workout days so that you're still cycling. Basically, just eat more. Track your progress for a few weeks, don't revert back to old ways due to a little 'undesired' fat gain, you should be conscious that putting on muscle (noticeable muscle) is very likely to come with fat gains as well.
If I was in your shoes, I'd do a Intermittent fasting diet for fat loss, muscle gain and health approach. The whole point of the site, if you're unfamiliar with it, is to gain muscle without gaining too much body fat.
For clarification, body weight strength training in as much as say push ups, dips, pull ups and other such exercises that are using one's body as a resistance weight can help develop muscle size and strength. Aerobic calisthenics like say jumping jacks, plyometrics ect aren't going to help a lean person to gain muscle size.
I've been doing a lot of inclined pushups, planks, and some door pull-ups lately. Just started looking into more I can do without weights until I can find a cheap gym and work out a decent schedule. Might give convict conditioning a look. I've pretty much cut out cardio completely.
Ah, I've heard about leangains and IF, but I don't know if it's right for me right now because I do have incidence of binge eating in my past as an overweight sedentary individual. And as someone who used to skip breakfast very often, reintroducing it was part of what helped me change my eating habits to begin with. IF may be something I'll consider further down the line.
Definitely going to up my carb intake more though. To the sweet potatoes!