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Hi, I'm Sean.

Co-founder & CTO at B3, building a crypto agent & decentralized inference. Previously Coinbase. I sweat the small details in software, and leave the good parts (components, free tools & writeups) out in the open here.

Sean Geng

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Speculative decoding and attention drift preview

Speculative decoding and attention drift

Speculative decoding gives you 2-6x faster LLM inference with output that is provably identical in distribution to the slow path, and the proof is short enough to fit in a terminal. The interesting failure mode is newer: push the draft model too deep and its attention slides off the prompt, acceptance collapses, and EAGLE-3.1 names the mechanism and fixes it.

ai
llm
inference
Real-time L1 proving: the cost curve marching down and to the left preview

Real-time L1 proving: the cost curve marching down and to the left

A zkVM proved a real Ethereum mainnet block faster than its own 12 second slot, on sixteen retail GPUs. This is the cost curve and the trust model behind that line, and why it's the actual engineering schedule for 10,000 TPS.

crypto
ethereum
zk
Process vs outcome rewards preview

Process vs outcome rewards

Before you tune anything on a reasoning RL run, you've already made the load-bearing decision: reward the answer or reward the steps. This walks the ORM vs PRM math on one concrete tree, shows why GRPO is quietly an outcome method, and why the reward that teaches fastest is also the easiest one in your stack to cheat.

ai
rl
reasoning
The KV-cache architecture wars preview

The KV-cache architecture wars

Every open-weight architecture trick from GQA to MLA to cross-layer sharing to compressed attention is an attack on one term in the same formula. Once you see cache = 2·L·n·d_kv·bytes, the whole 2026 model war collapses into four orthogonal levers you can pull yourself.

ai
llm
architecture
Jolt and the lookup singularity: when every instruction is just a table lookup preview

Jolt and the lookup singularity: when every instruction is just a table lookup

Most zkVMs hand-build a constraint system for every CPU instruction. Jolt skips that and turns each instruction into a single lookup into a table you never actually build, and the sum-check protocol underneath it is the same primitive doing the heavy lifting in GKR and Spartan.

crypto
zk
zkvm
Hybrid linear attention: rationing the quadratic preview

Hybrid linear attention: rationing the quadratic

Three frontier labs independently converged on the same 3:1 ratio of linear to full attention layers, and the reason isn't that linear attention got better, it's that a fixed-size state is structurally lossy. Deriving Gated DeltaNet, the memory-vs-length crossover, and why pure linear attention can't find the needle.

ai
llm
attention