Simon Willison’s Weblog

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Tuesday, 30th September 2025

Designing agentic loops

Coding agents like Anthropic’s Claude Code and OpenAI’s Codex CLI represent a genuine step change in how useful LLMs can be for producing working code. These agents can now directly exercise the code they are writing, correct errors, dig through existing implementation details, and even run experiments to find effective code solutions to problems.

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Having watched this morning's Sora 2 introduction video, the most notable feature (aside from audio generation - original Sora was silent, Google's Veo 3 supported audio in May 2025) looks to be what OpenAI are calling "cameos" - the ability to easily capture a video version of yourself or your friends and then use them as characters in generated videos.

My guess is that they are leaning into this based on the incredible success of ChatGPT image generation in March - possibly the most successful product launch of all time, signing up 100 million new users in just the first week after release.

The driving factor for that success? People love being able to create personalized images of themselves, their friends and their family members.

Google saw a similar effect with their Nano Banana image generation model. Gemini VP Josh Woodward tweeted on 24th September:

🍌 @GeminiApp just passed 5 billion images in less than a month.

Sora 2 cameos looks to me like an attempt to capture that same viral magic but for short-form videos, not images.

# 6:03 pm / gemini, generative-ai, openai, video-models, ai, text-to-image