SimGym

Simulating Humanity: from Generative Agents to 8 Billion Digital Twins — Joon Sung Park, Simile AI

Aug 21, 2026 · 1:11:01

Joon Sung Park, co-founder and CEO of Simile AI, joins Latent Space to argue that simulating humans requires bespoke behavior models, not just frontier LLMs, a bet rooted in his Generative Agents/Smallville paper. Frontier models optimized to be rational miss how people actually err, scoring 20–30% on niche populations, whereas Simile's digital twins match people's own responses 85% of the time. He details the three data buckets—interviews, observational data, and randomized controlled trials—and shows how companies use the platform for concept testing, A/B tests, and earnings calls. Park also shares the scaling-law glimpse in simulation, the economics of data-center-scale worlds, and his vision of simulating all 8 billion people to tackle wicked problems like climate change and UBI, with Thomas Schelling's agent-based models as precedent.

AI-Native Engineering: 100% adoption, 5x search throughput, unlimited tokens — Mikhail Parakhin

Apr 22, 2026 · 1:14:30

Shopify CTO Mikhail Parakhin details how the company achieved near 100% AI tool adoption, driven by a December 2025 inflection point where model quality triggered exponential token consumption. He argues token budgets matter only with strong critique loops: running multiple parallel agents without communication wastes tokens, while agentic PR review using large models—like GPT-5.4 Pro or Gemini Deep Think—reduces bugs even though latency increases. Parakhin unveils Tangle, Shopify's third-generation ML workflow system with content-based caching that eliminates duplicate computation across teams, and Tangent, an auto-research loop that optimizes pipelines—boosting search throughput from 800 to 4,200 QPS on the same hardware. SimGym simulates shoppers using decades of merchant data and browser-based agents to predict conversion changes, achieving 0.7 correlation with add-to-cart events. Shopify uses Liquid AI (non-transformer architecture) for sub-30ms query understanding and long-context tasks like catalog categorization, distilling larger models into Liquid for high-throughput batch jobs.