I really appreciate the Idea. Feels strange that this hasn't been in the specs since beginning...
Anyway I'd suggest to allow "🐼" at any position in the Graffiti (even multiple times). We should just enforce it's there at least once 😄

Edit:
I hope it's clear to everyone that this is an ironical PR and won't really get supported 😂
Would be funny to see a "🐼" in the merge transition block graffiti anyway.. I'll update my nodes accordingly 😉

• Allow 🐼 anywhere in graffiti
• Add unit tests

I really appreciate the effort! Imagine the Merge is stumbling because proposers are failing to put panda into the right place 😂 Btw, PR misses corresponding changes to validator.md. Even though they are done I can't give any promise on this change making it's way into the spec 😄

• Update validator.md to delay the merge if the configured graffiti lacks 🐼 by proposing a regular block without ExecutionPayload instead.

Just tell Mr. F. to change his graffiti.

The nice thing about this PR is that individual node operators, and even consensus layer implementations, can opt-in to support it on their own. Having a --graffiti-special=🐼 flag in nodes would allow staking pools etc to collaborate and try to get a message in for special occasions such as this one. The flag could be re-used in the future as well, and the marketing aspects are also valid factors (some people care more than others). Certain clients already implement panda art as well to celebrate the merge, so having a flag to override graffitis does not seem too far off: https://github.com/sigp/lighthouse/blob/aa72088f8fc91d41106a8afce7a0179cde64ce5d/beacon_node/beacon_chain/src/block_verification.rs#L85-L107

Regarding the consensus-layer rule: The way how it is proposed here is simple enough to implement, and makes inconsistencies between different Unicode libraries irrelevant – it is a simple check against a static sequence of data, and it does not interpret the graffiti as UTF-8 or run expensive string validation. It could be fun to see both false-negatives of people trying to apply skin-tone modifiers to other bears and getting rejected for trying to be too smart, or false-positives of people trying to make the panda-sequence appear as part of other characters but rely on different segmentation to have it actually rendered differently.

In the end, the miners are able to collaborate and decrease global hashrate to push the TTD far into the future (they would still have to buy up all the GPU stock to avoid others pumping hashrate), and with the panda PR, stakers could then proceed to delay the merge by avoiding the panda, because maybe they want to finish pruning their EL or whatever. This moves the authority to answer "when merge" entirely to the community (for both the EL and the CL).

🐼

I hope it's clear to everyone that this is an ironical PR and won't really get supported

Since @etan-status has not mentioned this is a joke, I will provide some feedback under the assumption that this PR is not a joke.

While I appreciate the effort to continue the panda meme, I think that having a spec level enforcement is an unnecessary complexity addition. It's another thing that could go wrong during launch. When thinking about the risk vs reward of this change, I do not think this spec level assertion to enforce the meme is worth any potential issues that may arise.

With that said, if the first block proposer does not include a panda emoji then I will be deeply disappointed.

🐼

It's another thing that could go wrong during launch.

On the other hand, allowing non-panda merge transition blocks would enable panda maxis to potentially trigger heavy forking around the transition period by orphaning those branches that they deem unviable. This PR mitigates this risk by allowing non-panda blocks to continue build a canonical chain as usual, until a panda is found. Should we really trust node operators who are unable to properly configure their graffiti with such a critical role during the PoS upgrade process?

🐼

🐼 art has been integrated into Nimbus: status-im/nimbus-eth2#3670

🐼 viewing in Windows command prompt, or Linux/macOS Terminal:

curl https://raw.githubusercontent.com/status-im/nimbus-eth2/v22.6.0/beacon_chain/consensus_object_pools/vanity_logs/blink-version.ans

(there is no | sudo bash in it, no worries).

closing due to insurmountable complexity and liveness issues

closing due to insurmountable complexity and liveness issues

** sad panda sounds **

GitHub has added a little banner on top of PRs from branches containing emoji (and Unicode RTL-overrides!), and appears to also have fixed the display of pandas in the little messages through the conversation when force-pushing such branches.