2026-04-10

Mon, 01 Jan 0001 00:00:00 +0000

Simon Willison — 2026-04-10#

Highlight#

Simon points out the non-obvious reality that ChatGPT’s Advanced Voice Mode is actually running on an older, weaker model compared to their flagship developer tools. Drawing on insights from Andrej Karpathy, he highlights the widening capability gap between consumer-facing voice interfaces and B2B-focused reasoning models that benefit from verifiable reinforcement learning.

Posts#

ChatGPT voice mode is a weaker model Simon reflects on the counterintuitive fact that OpenAI’s Advanced Voice Mode runs on a GPT-4o era model with an April 2024 knowledge cutoff. Prompted by a tweet from Andrej Karpathy, he contrasts this consumer feature with top-tier coding models capable of coherently restructuring entire codebases or finding system vulnerabilities. Karpathy notes this divergence in capabilities exists because coding tasks offer explicit, verifiable reward functions ideal for reinforcement learning and hold significantly more B2B value.

Simon Willison

Mon, 01 Jan 0001 00:00:00 +0000

Simon Willison — Week of 2026-04-04 to 2026-04-10#

Highlight of the Week#

Anthropic’s decision to delay the general release of their highly capable Claude Mythos model under “Project Glasswing” marks a significant turning point in the AI industry. The move underscores a massive shift in frontier model capabilities, as models evolve from generating text to autonomously chaining multiple minor vulnerabilities into sophisticated exploits, requiring a new level of security safeguards before release.