
#238 - GPT 5.4 mini, OpenAI Pivot, Mamba 3, Attention Residuals
Last Week in AI
Meta delays Avocado model rollout
Discussion of Meta's Avocado delay, internal tensions, and questions about organizational readiness for frontier models.
Our 238th episode with a summary and discussion of last week's big AI news!
Recorded on 03/18/2026
Hosted by Andrey Kurenkov and Jeremie Harris
Feel free to email us your questions and feedback at andreyvkurenkov@gmail.com and/or hello@gladstone.ai
Read out our text newsletter and comment on the podcast at https://lastweekin.ai/
In this episode:
* OpenAI released GPT-5.4 mini and nano with 400k-token context windows, higher per-token prices but claimed token-efficiency gains in Codex; nano is API-only and pitched for high-volume classification/data extraction despite a major price increase.
* Mistral open-sourced the Small 4 model family (MoE, 119B total/6B active) combining reasoning, multimodal, and coding-agent capabilities, and announced Forge to help businesses train or post-train custom models.
* Agent “operating system” competition intensified with Meta’s acquired Manus launching a local Mac agent, Nvidia announcing NeMo/“Open Shell” sandboxed agent runtime, and Nvidia also unveiling DLSS 5 plus major hardware forecasts including Groq LPU integration.
* Business and safety updates included OpenAI shifting focus toward productivity/enterprise amid competition, Microsoft reorganizing Copilot and frontier-model efforts, Meta delaying its next model, China-linked ByteDance deploying large Nvidia clusters abroad, and new safety work on steganography, chain-of-thought faithfulness, fine-tuning defenses, cyber-attack evals, and constitution/spec compliance.
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Timestamps:
- (00:00:10) Intro / Banter
- (00:01:56) News Preview
- Tools & Apps
- (00:02:39) OpenAI ships GPT-5.4 mini and nano, faster and more capable but up to 4x pricier
- (00:08:04) Mistral's new Small 4 model punches above its weight with 128 expert modules
- (00:14:03) Meta's Manus launches 'My Computer' to turn your Mac into an AI agent - 9to5Mac
- (00:17:57) NVIDIA Announces NemoClaw for the OpenClaw Community | NVIDIA Newsroom + Nvidia boosts knowledge work with Open Agent Development Platform
- (00:24:09) DLSS 5 looks like a real-time generative AI filter for video games | The Verge
- (00:26:36) OpenAI to Launch ChatGPT 'Adult Mode' Despite Warnings From Its Own Advisers - CNET
- Applications & Business
- (00:33:46) OpenAI Reportedly Pivoting to a Focus on Business and Productivity Only
- (00:41:25) Nvidia GTC 2026: CEO Jensen Huang sees $1 trillion in orders for Blackwell and Vera Rubin through ’27
- (00:45:44) Mistral launches Forge to help enterprises build their own AI models
- (00:54:17) China's ByteDance gets access to top Nvidia AI chips, WSJ reports
- (00:57:57) Meta Delays Rollout of New A.I. Model After Performance Concerns
- (01:02:50) Microsoft Shakes Up AI Division As Copilot Falls Behind Google and OpenAI
- Policy & Safety
- (01:07:26) A Decision-Theoretic Formalisation of Steganography With Applications to LLM Monitoring
- (01:13:09) Reasoning Theater: Disentangling Model Beliefs from Chain-of-Thought
- (01:18:29) In-Training Defenses against Emergent Misalignment in Language Models
- (01:23:07) How do frontier AI agents perform in multi-step cyber-attack scenarios?
- (01:25:20) Eval awareness in Claude Opus 4.6’s BrowseComp performance
- (01:29:49) Introducing Bloom: an open source tool for automated behavioral evaluations
- (01:32:26) How well do models follow their constitutions?
- (01:37:11) Nvidia’s H200 License Stirs Security Concern Among Top Democrats
- Research & Advancements
- (01:40:050) [2603.15031] Attention Residuals
- (01:47:11) Mamba-3: Improved Sequence Modeling using State Space Principles
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