Been deep in the ai-tldr.dev feed this week and there's a lot worth unpacking. Here are the three stories that actually changed how I'm thinking about AI in 2026. 1. GPT-5.5 Instant Is Now the Default — 52.5% Fewer Hallucinations OpenAI quietly swapped ChatGPT's default model to GPT-5.5 Instant, and the numbers on hallucination reduction in high-stakes domains (medicine, law, finance) are genuinely impressive. 52.5% drop is not a minor tweak — that's a step change in reliability. For those of us building LLM-powered apps, this matters. If the baseline model your users interact with is getting that much more factually grounded, the bar for "good enough" just shifted. Time to revisit your evals. 2. CopilotKit Raises $27M — AG-UI Is About to Become Infrastructure CopilotKit just closed a $27M Series A with Google, Microsoft, Amazon, and Oracle all in the same round. The AG-UI protocol — think MCP but for agent-to-UI rendering — is now backed by basically every major cloud provider simultaneously.…