Rinaldi Fonseca rinaldifonseca

LLM Wiki v2

A pattern for building personal knowledge bases using LLMs. Extended with lessons from building agentmemory, a persistent memory engine for AI coding agents.

This builds on Andrej Karpathy's original LLM Wiki idea file. Everything in the original still applies. This document adds what we learned running the pattern in production: what breaks at scale, what's missing, and what separates a wiki that stays useful from one that rots.

What the original gets right

The core insight is correct: stop re-deriving, start compiling. RAG retrieves and forgets. A wiki accumulates and compounds. The three-layer architecture (raw sources, wiki, schema) works. The operations (ingest, query, lint) cover the basics. If you haven't read the original, start there.

GenStage Tutorial

Introduction

So what is GenStage? From the official documentation, it is a "specification and computational flow for Elixir", but what does that mean to us?
There is a lot to something that can be described as that vague, and here we'll take a dive in and build something on top of it to understand its goals. We could go into the technical and theoretical implications of this, but instead lets try a pragmatic approach to really just get it to work.

First, Let's imagine we have a server that constantly emits numbers. It starts at the state of the number we give it, then counts up in one from there onward. This is what we would call our producer.

Not all random values are created equal - for security-related code, you need a specific kind of random value.

A summary of this article, if you don't want to read the entire thing:

Don't use Math.random(). There are extremely few cases where Math.random() is the right answer. Don't use it, unless you've read this entire article, and determined that it's necessary for your case.
Don't use crypto.getRandomBytes directly. While it's a CSPRNG, it's easy to bias the result when 'transforming' it, such that the output becomes more predictable.
If you want to generate random tokens or API keys: Use uuid, specifically the uuid.v4() method. Avoid node-uuid - it's not the same package, and doesn't produce reliably secure random values.
If you want to generate random numbers in a range: Use random-number-csprng.

You should seriously consider reading the entire article, though - it's

JWT Auth + Refresh Tokens in Rails

This is just some code I recently used in my development application in order to add token-based authentication for my api-only rails app. The api-client was to be consumed by a mobile application, so I needed an authentication solution that would keep the user logged in indefinetly and the only way to do this was either using refresh tokens or sliding sessions.

I also needed a way to both blacklist and whitelist tokens based on a unique identifier (jti)

Before trying it out DIY, I considered using:

Integrate Gem/Engine and main Rails app

Overview

Paths
Routes
Add functionality to controller
Improving (Extending or overriding) Engine functionality
Helpers
Assets

	iex(2)> pid = spawn Traps, :init, []
	waiting to die...
	#PID<0.92.0>
	Nobody tried to kill me! ^_^
	waiting to die...
	Nobody tried to kill me! ^_^
	waiting to die...
	iex(3)> Process.exit pid, :normal
	true
	(⊙＿⊙') somebody tried to kill me! {:EXIT, #PID<0.88.0>, :normal}

	defmodule Box do
	defmacro __using__(_env) do
	quote do
	import Box
	end
	end

	@doc """
	Define module with struct and typespec, in single line

	<!DOCTYPE html>
	<html>
	<head>
	<link href='https://fonts.googleapis.com/css?family=Roboto:300,400,500,700\|Material+Icons' rel="stylesheet">
	<link href="https://unpkg.com/vuetify/dist/vuetify.min.css" rel="stylesheet">
	<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no, minimal-ui">
	</head>
	<body>
	<div id="app">
	<v-app id="inspire">

	require 'logger'
	require 'byebug'

	require 'dry/monads'
	require 'dry/monads/do'
	require 'dry/matcher/result_matcher'

	module Dry
	module Transaction
	module Steps

	## PayRoll gem

	# lib/pay_roll.rb
	module PayRoll
	class << self
	attr_accessor :employee_directory
	def config
	yield self
	end
	end