Yep, one of the design decisions is the “reverse gas” model which allows keeping the barriers for dapp users low. (Btw. I think you wanted to say caller instead of callee in the inter-canister call example).
I think something like ic0.accept_message would be also useful for inter-canister calls because the callee still pays for the execution of its own code. Hence, you still need a mechanism to guard against DoS/cycle draining from another canister.
Great work! LGTM!
I think it would be great to extract this in a blog post or make PR to the docs or the Wiki. @ais, what do you think?
It would be a pity if this gets buried in the vastness of the forum.
Awesome, great work to you as well!
Agreed. I am willing to write and publish a blog post about this, but including it in the docs would be useful as well IMO.
I’m responding with @ais’s blessing.
We’d LOVE to have that in the docs, but we don’t want to rob you of an opportunity for a great blog post. @gabe, how would you like to do it? My personal favourite option would be to have it as a blog post on your own site, and then re-publish it on the docs page with very obvious credits and links back to the original.
I’d also love to see it in the docs and I think your suggestion sounds perfect! I’ll try to have a blog post ready within a week or so and make an update here once it’s ready.
Thank you very much, I’m looking forward to it!
Thought I’d share some interesting findings of my very rough calculations regarding the messaging protocol that I’m building. This estimate does not include costs for update instructions executed and assumes that a 100 kB message stored takes up exactly 100 kB of stable memory, i.e ignores data structures, etc.
Assuming worst-case where every message is the current maximum of 100 kB each, the estimated cost is:
…not one, not one thousand, but one million messages completely on-chain.
Pretty cool!
@gabe, awesome! This is a great collection of cycles-related information, I am also very much looking forward to the blog post and seeing this in the docs! 
Glad you found it helpful! I’m excited to share it as well and hope it can be of help to other devs.