
Guy Podjarny
5.4K posts

Guy Podjarny
@guypod
Founder @tessl_io, shaping AI Native Dev, Host of The AI Native Dev podcast & angel investor. Previously founder @snyksec, CTO @Akamai, founder @Blaze.io



"The code that we have is a liability. The system is the asset we're building." @chadfowler, VC at Blue Yard Capital (@blueyard) and former CTO at Wunderlist, sits down with @guypod to discuss the Phoenix Architecture: software designed to be replaced rather than maintained. In this episode: • why was the code written by Chad never longer than a page • how he replaced 70% of a codebase in 3 months and cut costs by 75% • shipping AI code no human ever reviewed, and how to make it safe • the shadow specs your agents are making without you • why your system should work with the worst LLM, not just the best If you're still thinking about your codebase the old way, this one will change that. (0:00) Trailer (1:07) AI DevCon (2:01) Introduction (3:41) Origin story: euthanising legacy systems (5:45) Immutable infrastructure as inspiration (6:48) Disposable software and immutable code (9:00) Cattle versus pets for code (10:03) Making disposable code feasible at Wunderlist (12:31) Phoenix Architecture (15:16) Extreme programming lesson: do hard things constantly (17:04) What level of detail should specs have? (19:15) Pace layers and stable regeneration (22:37) New programming languages versus patterns (29:47) Compiling to system architectures (30:45) Training the programmer versus defining the system (35:03) Personalised and malleable software (37:48) Local first and shared data models (45:08) Evaluations as the real codebase (49:36) Testing the agent versus testing the system (55:38) Path of adoption (01:00:48) Wrap-up


Agent skills help agents use your products, build in your codebase and enforce your policies. They're the new unit of software for devs - but most are still treated like simple markdown files copied between repos with no versioning, no quality signal, no updates. Without AI evaluations, you can’t tell if a skill helps, provides minimal uplift or even degrades functionality. You spend your time course-correcting agents instead of shipping. @tessl_io is a development platform and package manager for agent skills. Today, I’m excited to launch on Product Hunt and announce that you can evaluate your skill and optimize them on Tessl. This means you can stop debugging agent output and start shipping quality code, faster. Real example: we've helped ElevenLabs ship skills that double agent success in using their APIs. If you're building a personal project, maintaining an OSS library, or developing with AI at work, you can now evaluate your skill and optimize it to help agents use it properly. Check us out on Product Hunt. If it’s useful, we’d love your upvote - and even more, your feedback in the comments: producthunt.com/products/tessl…







Agent skills help agents use your products, build in your codebase and enforce your policies. They’re not just words - they are what the unit of software for agentic devs, and need powerful dev tools to match. That is what @tessl_io offers. Tessl is the package manager and development platform for skills. It offers a full dev lifecycle, helping you generate, evaluate, distribute and observe skills & context, developing them to the professional grade they warrant. Today, I’m excited to announce the general availability of our task evals, which help you understand how good your skills are. Such insight is critical to making your skills great, avoiding regression, and applying learnings from their real world usage. For example: @Cisco's software-security skill shows a 1.8X improvement in securing coding in its benchmark, and @ElevenLabs's agents skill boosts success by almost 3X! However, not to name names, we often see skills that provide minimal uplift while consuming context window space, or even degrade functionality. As Spencer Kimball, CEO of Cockroach Labs, put it when we shared early versions of this: evaluation is what makes agentic coding outcomes converge instead of drifting. Task evals are joining a long list of powerful context development tools, such as: * Review skills against quality best practices * Generate and maintain skills and docs for using your libraries & platform * Distribute versioned skills to your dev team and ecosystem * Consume skills easily and safely, and keep them up-to-date Skills are a central part of software development. If you’re serious about making agentic dev successful in your org, or helping your customers’s agents use your products, you need to invest in them. We hope Tessl can help. Check out links in the thread to get started!

Agent skills help agents use your products, build in your codebase and enforce your policies. They’re not just words - they are what the unit of software for agentic devs, and need powerful dev tools to match. That is what @tessl_io offers. Tessl is the package manager and development platform for skills. It offers a full dev lifecycle, helping you generate, evaluate, distribute and observe skills & context, developing them to the professional grade they warrant. Today, I’m excited to announce the general availability of our task evals, which help you understand how good your skills are. Such insight is critical to making your skills great, avoiding regression, and applying learnings from their real world usage. For example: @Cisco's software-security skill shows a 1.8X improvement in securing coding in its benchmark, and @ElevenLabs's agents skill boosts success by almost 3X! However, not to name names, we often see skills that provide minimal uplift while consuming context window space, or even degrade functionality. As Spencer Kimball, CEO of Cockroach Labs, put it when we shared early versions of this: evaluation is what makes agentic coding outcomes converge instead of drifting. Task evals are joining a long list of powerful context development tools, such as: * Review skills against quality best practices * Generate and maintain skills and docs for using your libraries & platform * Distribute versioned skills to your dev team and ecosystem * Consume skills easily and safely, and keep them up-to-date Skills are a central part of software development. If you’re serious about making agentic dev successful in your org, or helping your customers’s agents use your products, you need to invest in them. We hope Tessl can help. Check out links in the thread to get started!



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