co-founder & CTO @Letta_AI making machines that learn prev phd @ucbrise @BerkeleySky + @MIT

San Francisco, CA
Sarah Wooders retweeted
Lately my #1 pet peeve in agent harnesses has been any sort of execution-blocking tools. Latest victim is AskUserQuestion. Nuked in the Letta Code CLI, replaced with a fully async AskUserQuestion registered by the client (the user may never answer the question, but that's OK).
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Sarah Wooders retweeted
Replying to @GayaniFigma
Hey @GayaniFigma , I think in spirit, when I created MCP, I envisioned an open ecosystem. That to me feels core. Seeing restrictions like this is sad and I hope Figma can get to a point where it’s more open or at least make the process of getting into the allowlist very easy.
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Sarah Wooders retweeted
Letta's dynamic workflows are very cool. - Works with any model -- Opus 5.5 can orchestrate DeepSeek v4.1 or Luna - Supports Jev for making decisions in workflows - Gets you out of the Anthropic/OpenAI ecosystem and lets you own your own context Ask your agent about workflows!
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Agents are getting very good at writing code and managing subagents. With dynamic workflows, Letta Code agents can now write code that orchestrates both: • agent() → run a subagent • decide() → call a decision model By composing these calls in pipeline or in parallel, agents can take on large tasks and process huge amounts of context (e.g. learning from past trajectories) I'm especially excited about how Decision APIs can help save costs for dynamic workflows. Decision models are fast and cheap, so a workflow can filter work before spending an agent on it. And since subagents are model-agnostic, each step can run on the most cost-effective model -- you could even potentially use a decision model to choose what model to run a task on!
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I keep on seeing people posting about how no one they know uses Devin, but I know lots of people who use Devin?? Weird how non-uniform their distribution is
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I'm very excited about both multi-agent and also *multi-machine* orchestration by agents. Subagents in @Letta_AI can be called on a different computers - e.g. below my agent called one agent to run in the same cloud sandbox, and another to inspect something on my laptop.
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Sarah Wooders retweeted
You can use your Letta agent to coordinate context across all your agents using our new MCP server. Here is me setting up @Muse to talk to Co, my personal Letta agent. Full prompt below 👇
Using Muse to dispatch work to my @Letta_AI cloud agent, which can be orchestrated via MCP MCP is the real A2A
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Using Muse to dispatch work to my @Letta_AI cloud agent, which can be orchestrated via MCP MCP is the real A2A
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The cloud revolution is finally coming to personal computing
I’ve seen a couple of posts about this so wanted to demystify. Today, every Muse user gets a free computer in the cloud. It's a real computer, and we’ve designed the security architecture of the Muse Secure VM carefully so you and your Muse can do almost anything you could with a computer sitting under your desk while keeping you and the system safe from threats like prompt injection. We wrote about this at length in our security blog post – security.muse.ai. Activity in the “runtime cell”, which you share with your Muse is unfettered, but sensitive actions are all overseen by the Sentinel, which runs outside of that cell. Similarly, all sensitive secrets - like the passwords you enter into Muse’s secure credential storage - are also stored outside the runtime cell. The runtime cell gets its own root filesystem (including a full Ubuntu linux image) separate from the host filesystem where your other more sensitive data lives. Because it is isolated from the sensitive stuff that runs on the same box, this means that we can, and do, offer users full visibility and control over the files in the runtime cell. Just as you can when you install Linux on your home computer, you can poke around and see all the files that make the system work - both debian system files and the binaries and data files that implement the parts of Muse which run in the runtime cell. This was a very deliberate choice - your Muse Secure VM truly is your own computer in the cloud. You can install software in it, write and compile code, use the browser to surf the web: it is your own Linux box that you can operate as you choose with your Muse. Poking around in this computer doesn't give you any privileged access to Meta infrastructure, or to other people's data If I may geek out a little here for a second… As a kid I loved to take things apart to see how they worked. As a teenager I got into computers and soon found myself drawn to C:\WINDOWS\SYSTEM and the system registry, later Slackware’s /dev/, /proc/ etc – I could see how the system was laid out and as I explored what DLL files and .so files actually did, I gradually became able to meld the computer to my own will. We’re really proud to be able to put a real computer in millions of people’s hands with a similar level of transparency. We built a file explorer right into the Library tab of the UI. We want you to be able to see the markdown files Muse writes while it thinks about how to serve you better, and explore the internals of the system if you’d like to. So, when you ask your Muse to show you its entire filesystem, and receive gigabytes of files you’re seeing the full contents of the runtime cell. It’s yours to explore and enjoy! If you’re not a geek like me, or simply want to download the data that you personally have created directly with your Muse, we added a feature for that too in Settings > Data controls > Download your agent data.
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I fear our slack may be all agents soon
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Sarah Wooders retweeted
Opus 5.5, GPT 6 Sol, and GPT 6 Luna are now all available on Letta Code!
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GPT 5.2 was the first model where I realized I was starting to lose most of our arguments
In a first, today I was staring at a piece of AI generated code that had a subtle bug, and then realized the AI had gotten it right and I'd introduced the bug while editing it. DMs are open, AMA about software engineering.
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All harnesses are converging towards MemGPT: - heartbeats - editable memory (human/persona) - a send_message() tool
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Getting Slack DMed for feedback by an agent (that's not mine) 👀
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Sarah Wooders retweeted
Stateful agents in a team setting + Astra's agent-to-agent messaging capabilities is really a sight to behold. My agent now proactively reaches out to other agents on our team that might be doing overlapping work to coordinate (in this case @sarahwooders 's venerable Bob)
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How long until we have nested skills?
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For people who use Claude Code / Codex / pi / etc - do you share agent traces across your team? If so, how?
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Sarah Wooders retweeted
Muse can install the Letta Code CLI, so I asked Muse to set up a play date with my long-time personal agent Co. Here are images each of them generated from the playdate.
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Any feature of a harness (i.e. anything beyond the minimal requirements of a `bash` loop) makes the harness more complex -- it's more tokens, and more stuff for the model running inside of it to understand. Harnesses like Claude Code and Codex are designed to work well out of the box for *everyone*. But that also means that a lot of what the harness offers is unnecessary or inhibiting for specific usecases. If you care about picking the specific subagent of features you need, you can use something like Pi to minimize token usage. If you care about memory and scaling sleeptime compute, you can use a harness like @Letta_AI to create stateful agents with affordances for self-adaptation and long-term persistence.
Does your Claude model really need Claude Code…? 🤔 We evaluate 7 models on Claude Code, Codex, and Pi. Three surprising findings emerge: 1️⃣Harness choice has little effect on task success rate, but can significantly affect the cost 2️⃣A simple harness can be competitive 3️⃣The native harness isn’t always the best. Millions of people are using coding agents, but the impact of harness choice remains unclear. (1/n) More details in the thread. 🧵
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