Top all-time · #2359
Earendil
Company blog · earendil.com/postsprogrammingai
Earendil is the company blog at earendil.com, writing about programming and ai. Since 2026, 30 different Hacker News readers have linked it 42 times, most often “Prompt Caching in Agents”. It is still writing: the last post was on 2026-10-16, and you can follow it by feed.
Too few sampled comments (16) to say how often HN recommends it.?
Why HN links it
HN readers link Earendil's posts, by the team behind the Pi coding agent, to explain agent harness design, session portability, prompt caching and MCP. Comments point to them as explanations of how harnesses work.
Summarised by Claude from a sample of 16 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
Earendil is a public benefit corporation crafting software and open protocols to strengthen human agency, bridge division, and cultivate lasting joy.
Most-linked posts?
- Prompt Caching in Agents5 people · 5 mentions · first linked 2026-07-23
- The Session You Cannot Take with You4 people · 5 mentions · first linked 2026-07-30
- You said no MCP4 people · 4 mentions · first linked 2026-09-29
- What Is a Harness?3 people · 4 mentions · first linked 2026-08-20
- Pi Durable on Cloudflare – Earendil3 people · 3 mentions · first linked 2026-10-16
- Pi's Minimalism Is Its Advantage2 people · 3 mentions · first linked 2026-08-04
- How Compaction Works in Pi2 people · 2 mentions · first linked 2026-08-13
- Measuring the sloppiness of code2 people · 2 mentions · first linked 2026-09-11
- There are many agent harnesses, but this one is mine2 people · 2 mentions · first linked 2026-09-03
- Pi Durable2 people · 2 mentions · first linked 2026-10-01
What Hacker News says?
They actually mention this at the end of their post on Pi Durable[0]: > Why TypeScript again? Because it is the easiest way to bootstrap this. But as everybody knows by now, it's very easy to port everything to Rust or assembler. We're not ruling this out in the future, but at the moment we are focusing on TypeScript. [0]: https://earendil.com/posts/pi-durable/
Comment linking /posts/pi-durable/
on “Pi 1.0”Submitted Pi 1.0 as a story · 1689 points
HN discussionA year later, some things have changed: https://earendil.com/posts/you-said-no-mcp/
Comment linking /posts/you-said-no-mcp/
on “Pi 1.0”Submitted You said no MCP as a story · 687 points
HN discussionNot what we stand for: https://earendil.com/values/
Comment linking /values/
on “Pi 1.0”Submitted What Is a Harness? as a story · 589 points
HN discussionWithout going through the following flow I very quickly end up with nitty recurring micro bugs or interaction "gunk" and 10's of thousands of lines of pointless code that bloats out the code-base and agent's context. plan -> approve -> agent codes -> review code -> cleanup and pointing to specific skills/agents depending on what the issues are and some manual instructions pointing to specific lines of code-> agent c…
Comment linking /posts/measuring-code-sloppiness/
on “Show HN: Whiteboard (YC W26) – An open-source IDE for thoughtful software design”Submitted Pi Durable as a story · 515 points
HN discussionWhy is this a personal blog, not a Pi post? https://earendil.com/posts/you-said-no-mcp/ remains difficult to read without understanding what codemode is, with some quote like "Now we talked so much about Codemode, it might be worth explaining what that even is."
Comment linking /posts/you-said-no-mcp/
on “What is Codemode”Submitted Measuring the sloppiness of code as a story · 295 points
HN discussionthe one by https://earendil.com/posts/what-is-a-harness/ is also a good read and if you want to see what a simple harness implementation looks like you can just dive into the code and ask your favorite agent about it https://github.com/smol-env/smol https://github.com/earendil-works/pi
Comment linking /posts/what-is-a-harness/
on “Harness Engineering”Submitted Pi Durable on Cloudflare – Earendil as a story · 13 points
HN discussionI think this article posted to HN last week did a better job explaining things IMO https://earendil.com/posts/what-is-a-harness/
Comment linking /posts/what-is-a-harness/
on “Harness Engineering”Submitted You Said No MCP as a story · 9 points
HN discussiontbh I think it is just a question about time before flask guy has something to sell: https://earendil.com/
Comment linking /
on “Don't fall into the anti-AI hype”Submitted There are many themes, but this one is yours as a story · 5 points
HN discussionAccording to [1] there is - unfortunately - increasingly more state in LLM sessions. 1: https://earendil.com/posts/session-portability
Comment linking /posts/session-portability
on “Qwen3.8-Max: A New Bar for Coding and Cowork”Submitted The Session You Cannot Take with You as a story · 4 points
HN discussionWhich is why big labs have been working hard on making their harness not be stateless any longer: https://earendil.com/posts/session-portability/ “Just take the session thread to another provider” might not be feasible anymore soon-ish.
Comment linking /posts/session-portability/
on “Qwen3.8-Max: A New Bar for Coding and Cowork”Submitted There are many agent harnesses, but this one is mine as a story · 3 points
HN discussionPi is pretty good actually (it has way less context spam, fewer tools and smaller system prompt than the usual suspects) databricks also looked at this: https://earendil.com/posts/pi-autoresearch-and-databricks/
Comment linking /posts/pi-autoresearch-and-databricks/
on “Agent skills that bring team coding standards to Claude Code and Codex”Submitted Pi's Minimalism Is Its Advantage as a story · 3 points
HN discussionLike glm-5.x I think it has enormous self introspection that it often trips up on, but that this self reflection is actually a superpower, that enables incredibly good output. And from (in some cases) very small models. If you watch it think, which you can, unlike American closed models, you can steer it. You can provide a a massive rocket ship stratospheric boost to help it orient itself. You have no self correctio…
Comment linking /posts/session-portability/
on “U.S. Department of Energy Launches the Genesis Open Models Initiative”Submitted There are many themes, but this one is yours as a story · 2 points
HN discussionAs low as it is, switching between providers on OpenRouter is still lower. That said, it's a fair point. For me, it boils down to things covered here: https://earendil.com/posts/session-portability/ Things like obscured reasoning traces.
Comment linking /posts/session-portability/
on “Qwen3.8 Max now ranked as the best overall model by agentic index”Submitted There are many agent harnesses, but this one is mine as a story · 2 points
HN discussionBecause if you don't, you trash the KV cache and things get way more expensive. We wrote about it here: https://earendil.com/posts/prompt-caching/ Encrypted reasoning content is one of the things we keep as blobs in the transcript, even though we can only send it back to the original provider that created them, as otherwise we cannot keep caches live.
Comment linking /posts/prompt-caching/
on “The Session You Cannot take with you”Submitted What Is a Harness? as a story · 2 points
HN discussionAnd yet https://earendil.com/purpose/ is dabbling in AI and many posts by Ronacher are low key promoting AI. He is contributing to the madness.
Comment linking /purpose/
on “Some Things Just Take Time”Submitted How Compaction Works in Pi as a story · 2 points
HN discussion
