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Why We Made Jev — Diogo Almeida, TypeSafe Co-founder & CEO

Latent Space PodcastLatent Space Podcast
Science & Technology6 min read143 min video
Sep 21, 2026|9,105 views|375|43
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TL;DR

TypeSafe's Jev model redefines AI by prioritizing machine-native programmability and intelligence per dollar, moving beyond chat-based models to power a new wave of automation.

Key Insights

1

Jev is TypeSafe's first 'system one model,' designed to be machine-native and directly consumable by code, prioritizing intelligence per dollar over raw speed or cost alone.

2

The launch of Jev represents a fundamental shift away from Reinforcement Learning from Human Feedback (RLHF) models, which can suffer from 'mode dropping' or collapsing towards what users want to hear, rather than true confidence.

3

TypeSafe is strongly opposed to safety alignment at the API layer, viewing it as a 'type error' that hinders software development, and advocates for developers to manage safety at the application level.

4

The company actively discourages public benchmarks, believing they are easily gameable and antithetical to building trust in AI intelligence, preferring instead to rely on user workflows and 'vibes' for evaluation.

5

Jev's core primitives are 'choice,' 'score,' and 'null,' which are intentionally new concepts designed to map closely but not identically to programming primitives like enums, integers, and booleans, to avoid confusion and encourage precise usage.

6

TypeSafe views its models as akin to UDP, forming a foundational layer upon which developers can build diverse and complex applications, aiming for an 'AWS of intelligence'.

The 'System One' Model: A New Paradigm for AI

Diogo Almeida, co-founder and CEO of TypeSafe, introduces Jev, their groundbreaking model, not as just another large language model, but as the first of a new class they term 'system one models.' These models are designed to be machine-native, meaning their output is intended for direct consumption by code. This is a significant departure from current LLMs optimized for autocompleting internet text (pre-trained LLMs) or responding to human instructions (RLHF models). The core philosophy behind system one models is to integrate AI deeply into software, making it as powerful as possible. Jev, named after Jevons paradox, is specifically optimized for 'intelligence per dollar,' a metric that balances performance with cost-effectiveness. This focus on efficiency and programmability is central to TypeSafe's vision for enabling a new era of AI-driven economic revolution.

Critique of RLHF and the Problem of Mode Dropping

A key motivation behind Jev and TypeSafe's approach is a critique of Reinforcement Learning from Human Feedback (RLHF), a popular method for fine-tuning LLMs. Almeida explains that RLHF models can suffer from 'mode dropping' or 'mode collapse,' where the model tends to avoid making probabilistic errors by converging on a limited set of safe or common responses. This means the model might not accurately reflect its internal confidence about an answer but rather what it predicts the human user wants to hear. This phenomenon, Almeida argues, is a significant reason why current LLMs can be unreliable for complex decision-making tasks and why they fail to generalize as well as they theoretically could. The aim of system one models is to move beyond this limitation by focusing on calibrated decision-making and more reliable outputs.

Rejection of API-Layer Safety Alignment

TypeSafe holds a strong stance against implementing safety alignment directly within their API. Almeida argues that while safety is important, embedding it at the API level creates a 'type error' for developers. He contrasts this with consumer-facing products like ChatGPT, where user-specific safety preferences (e.g., refusing certain role-plays) might be understandable. However, for an API intended to be a foundational component of software, such restrictions are seen as fundamentally anti-developer. The concern is that these built-in refusals can cause software to break unpredictably when users interact with dependencies they may not fully understand. TypeSafe believes that developers should have the freedom to build and manage safety within their applications, rather than having it imposed by the AI provider.

Emphasis on Reliability Over Determinism

Almeida clarifies TypeSafe's view on reliability, distinguishing it from strict determinism (same input always yields the same output). While determinism might be useful for unit tests, he argues that robustness—similar outputs for similar inputs—is a more critical property for AI systems. He highlights how LLMs are often unreliable in this regard, even for semantically identical questions. TypeSafe's focus is on ensuring that their models consistently perform the desired task, even if the exact output varies slightly. This robustness is crucial for AI to be trusted in real-world applications, especially when making decisions. While determinism could be an option, it's seen as a trade-off that would reduce 'intelligence per dollar,' which is TypeSafe's primary optimization goal.

The 'Intelligence per Dollar' Frontier

A recurring theme is the pursuit of 'intelligence per dollar.' Jev aims to be at the frontier of this metric, meaning it provides the most 'intelligence' for its cost. Almeida emphasizes that while speed and cost are important, intelligence is the ultimate value. This metric is central to their strategy, leading them to pursue 'disgusting things' to optimize it. This drive for efficiency explains their focus on system one models and their potential resistance to features that might increase costs or reduce intelligence density, such as strict determinism or potentially certain types of fine-tuning if they don't align with this core metric.

API Design: New Primitives for Machine-Native Interaction

TypeSafe has introduced novel API primitives: 'null,' 'score,' and 'choice.' These are intentionally not direct mappings to existing programming types to avoid confusion and encourage precise interaction. 'Null' is described as a continuous boolean, 'score' is analogous to LLM judgments or probabilities, and 'choice' is akin to a function call or a switch statement on an enum. These primitives are designed to be consumed by code, allowing programs to insert them directly into their logic. The goal is to make AI interactions more structured and semantic, moving away from string-based templating towards a more robust and legible programming paradigm. TypeSafe emphasizes that these are outputs, but the input state, instructions, and criteria can also be structured JSON objects, further facilitating machine-native integration.

Beyond Chatbots: The Future of Programmable AI

Almeida expresses a strong belief that the future of AI lies not in chat interfaces but in programmable, machine-native systems. He argues that while current LLMs can solve complex math problems, they still fail to automate basic, repetitive tasks due to a lack of proper integration. Jev and TypeSafe's approach aims to provide the 'right plugs' to connect AI's power to economically valuable work. They envision AI becoming the underlying infrastructure, similar to TCP/IP, upon which developers can build a vast array of applications. This future promises an 'AI-based economic revolution' and a return to the 'early internet energy' of creation and innovation.

The 'Bitterest Lesson' and the Importance of the Right Task

Referencing Rich Sutton's 'Bitterest Lesson,' Almeida stresses that while compute and data are important, having the 'right task' or northstar is the most critical factor for AI progress. He identifies key shifts in LLMs, such as the move to RLHF for instruction following and now their own RLCD (Reinforcement Learning from Code Decisions) for programmable AI. He argues that TypeSafe is focused on discovering and executing these correct tasks, which is more valuable than simply scaling existing methods. This philosophy underpins their data-centric approach, viewing model capabilities as intrinsically linked to the quality and nature of the data used.

Common Questions

Jev is TypeSafe's first large programmable 'system one' model, optimized for intelligence per dollar. Unlike traditional large language models (LLMs) meant for text-based autocomplete or chatbots, Jev is designed for code to be the primary consumer, integrating directly with software for powerful automation.

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