edited blogpost

app/priv/blog/engineering/2026/04-18-coding-agent-generates-its-own-extensions.md

@@ -1,104 +0,0 @@
-%{
-  title: "Coding agent generates its' own extensions",
-  author: "Willem van den Ende",
-  tags: ~w(ai loops),
-  description: "Handwritten note",
-  published: false
-}
----
-
-I see a few people writing about
-sharing struggles with Llm's.
-
-for me it is easier to do at
-the moment of a small success.
-
-The challenge with writing about
-my experiments is that it gets meta pretty quickly.
-
-therefore I am going to leave out
-a bunch of things, including this commentary.
-
-the other day I tried to develop on
-extension for pi - the shitty coding agent, that would stop a model when it
-goes off the rails.
-
-I now have a local model that
-is fast, can call tools (edit Files, run test, etc) edit code etc.
-
-It does, however, perform some model assisted coding quinks frequently:
-
-- replace production code that Works With throwing an exception
-
-- write if statements in tests
-- add fallbacks for things that can't fail
-
-- Find "problems" in that works
-	(passes tests + other checks, works for
-		the user etc)
-
-Long form the Solution probably is to work
-in small Steps. But these steps come From
-experience.
-
-Catching the hovel when it happens by
-simply matching Some Lords is a starting point for that: scan for key words in
-any edits on a prompt the user for permission, or abort when the session is not interactive.
-
-Looks simple, so I let a more powerful
-but slower local model figure out how to build an extensions - pi has a system prompt for that -. After cone iteration
-we had a plan and pi generated d
-plausible looking extension.
-
-I tested it manually, in pi. Nothing happened. Back to the drawing board.
-
-I had quite a few iterations, compared with
-sample code, looked into the pi API,
-70 luck.
-
-Eventually I installed the sample extension. that worked. then I deleted most of my
-extension, added some logging - I could
-see sore thing.
-
-I learned while a bit about pi and its extension mechanism.
-
-It looks like only the last "UI notification" gets shown for any exension point (e.g. a fool call or system startup).
-
-I am not get sure if this is by design or not.
-
-I did take away the, here too, I wont to work test-first for parts that do not interface
-with the agent directly. The feedback loop
-is just too slow.
-
-this also ren vired experimentation. I did not want to set up a separate project for
-an extension that is little more than an idea. But I do want tests
-
-to asked a model again. and suggestion was
-to use Deno, because that has testing built
-in. Some more Fiddlig Adowed:
-
-- get Dena to work in the Sandbox
-- Learn that pi auto loads any thing in
-	the excusions folder. If you put a test there,
-	pi crashes
-- learn that" domain" files also don't work there.
-
-So eventually I ended up with
-
-```
-- .pi/ test
-	/ core
-	/ extensions
-```
-
-Core contains the functional cores tests ter the core, exertion, is a thin integration with
-pi that uses the core.
-
-this was clear enough that the slow, dense model could build a second extension & performance metrics in chat.) with relatively little guidance after iterations on a plan.
-
-I haven't looked at the code bet. not
-out of principle, but because it is late,
-and I want to write down my trial and error before I forget.
-
-TODO link pdf
-TODO add image from scan (in downloads)

app/priv/blog/engineering/2026/04-19-coding-agent-generates-its-own-extensions.md

@@ -0,0 +1,83 @@
+%{
+  title: "Coding agent generates its' own extensions",
+  author: "Willem van den Ende",
+  tags: ~w(ai loops),
+  description: "Handwritten note about generating extensions for the coding agent you are in a session with on something else. Engineer solutions in the moment.",
+  published: true
+}
+---
+
+(This post was written longhand. Conversion to text was done with MyScript Notes, I did some minor manual edits to correct words and explain a few things (in parentheses) See the Afterword for what happened since writing this).
+
+
+I see a few people writing about sharing struggles with Large language models, saying we are all still figuring this out.
+
+For me it is easier to do at the moment of a small success.
+
+The other day I tried to develop an extension for [Pi](https://shittycodingagent.ai) model when it goes off the rails.
+
+I now have a local model that is fast, can call tools (search, run test,  edit code etc.). It does, however, perform some model assisted coding quirks frequently:
+
+- Replace production code that Works With throwing an exception
+- Write if statements in tests
+- Add fallbacks for things that can't fail
+- Find "problems" in code that works (passes tests + other checks, works for the user etc)
+
+Long term the solution probably is to work in small steps. But these steps come from experience.
+
+Catching the problem when it happens by simply matching some words is a starting point for that: scan for key words in any edits and prompt the user for permission. Just abort when the session is not interactive.
+
+Looks simple, so I let a more powerful but slower local model figure out how to build an extensions. Every Pi session opens with an invitation:
+
+> Pi can explain its own features and look up its docs. Ask it how to use or extend Pi.
+
+After some iteration we had a plan and Pi generated d plausible looking extension.
+
+I tested it manually, in Pi. Nothing happened. Back to the drawing board.
+
+I had quite a few iterations, compared with sample code, looked into the Pi API.
+No luck.
+
+Eventually I installed the sample extension. That worked. Then I deleted most of my
+extension, added some logging - I could see something.
+
+I learned quite a bit about Pi and its extension mechanism.
+
+It looks like only the last "UI notification" gets shown for any exension point (e.g. a tool call or system startup). I am not yet sure if this is by design or not.
+
+I did take away that, here too, I want to work test-first for parts that do not interface
+with the agent directly. The feedback loop is just too slow otherwise.
+
+This also required experimentation. I did not want to set up a separate project for an extension that is little more than an idea. But I do want tests. So I asked a model again. The suggestion was to use Deno, because that has testing built in. Some more fiddling followed:
+
+- Get [deno](https://deno.com/) to work in the [nono](https://nono.sh/cli) sandbox
+- Learn that Pi auto loads any thing in the extensions folder. If you put a test there, Pi crashes. (the test does not have the method that defines an extension. All files in `.pi/agent/extensions` must have it.)
+- Learn that "domain" files also don't work there. (I wanted to have the extension files thin and the testable functions separate. So that the tests don't depend on `pi` and its' types).
+
+[!handwritten draft of the paragraphg below](/images/blog/2026/local-llm-handwriting.png)
+
+
+So eventually I ended up with
+
+```
+- .pi / test
+	  / core
+	  / extensions
+```
+
+`Core` contains the functional cores, `test` tests the core. `Extensions` is a thin integration with Pi that uses the core. (the Deno project lives in )
+
+This was clear enough that the slow, dense model could build a second extension and performance metrics in chat, with relatively little guidance after iterations on a plan.
+
+I haven't looked at the code yet (in detail). not out of principle, but because it is late,
+and I want to write down my trial and error before I forget.
+
+Afterword
+---
+
+I hope you enjoyed this slowly written note. I have added the
+[handwritten draft](/images/blog/2026/coding-agent-generates-extensions-handwritten.pdf) as pdf. 
+
+I found writing in long hand helped me slow down and step away from the slot machine that wishcraft can be sometimes.
+
+