My guard hook found nc in cancel
In five weeks my Claude Code guard hook blocked 82 commands in my own projects. 53 were the exfiltration rule, and only one looked like what that rule is for. The agent learned to route around it.
Ronnie Miller
My name is Ronnie. I'm a product-minded software engineer, building SaaS products and the infrastructure that runs them.
I live on California's Redwood Coast and have been building software for over 15 years. That work covers code, cloud infrastructure, security, and leading engineering teams.
Currently, you can find me leading engineering efforts as Partner and CTO of KABI Automotive. I also explore the edges of AI at BuildTestRun and share what I'm building and learning on my YouTube channel, Build at Scale. The notes below are where I write down what I build and what breaks.
Latest
Recent
Images in a PR from a fork
I wanted test screenshots in a PR as native GitHub attachments. gh can attach files now, but only with write access to the repo that holds the PR. From a fork into a read-only repo, that left the web editor.
Claude's Bash tool runs my zsh
Claude Code runs Bash tool commands in my login shell, which is zsh. Over five weeks, five zsh behaviors broke bash-style one-liners, and one grep error happened 29 times.
Old code read what the canary wrote
A branch ran against shared databases and queues before it merged. Its jobs, its mailer, and one new STI row reached code on main that had never heard of those classes.
A bare wait also waited for tee
A setup script for a Claude Code cloud environment never finished. A prebuilt Ruby only ran from its build path, and a bare wait was waiting on the tee process that logged the script.
AWS WAF blocked MCP sign-in from desktop apps
An MCP server in a Rails app signed in fine from claude.ai, but desktop clients got a 403 from the load balancer. A managed WAF rule read the loopback redirect URL in the OAuth request as an SSRF attempt.
YJIT under Rosetta was five times slower
A Rails test suite took 5 minutes per suite on an Apple silicon Mac. The container was amd64 under Rosetta with YJIT on, and one spec file ran in 3.5 minutes instead of 28 seconds.
Archive
Ruby and Rails 30
- Old code read what the canary wrote
- YJIT under Rosetta was five times slower
- A time on a date column moved the month
- CONVERT TO runs after MODIFY
- chruby picked the broken Ruby
- Three ways Puma didn't restart
- Notes from Rails 6.1 to 8.1 in a day
- Where the email link 404s came from
- A new cookie domain needs a new cookie name
- A hash without braces became keyword arguments
- driven_by replaced my Chrome driver
- The relation ran after the block ended
- Two Ruby managers, one gem directory
- Setting config.hosts dropped the defaults
- Time.local doesn't know the Rails zone
- Capybara waited for a request my test never checked
- nginx returned 405 for PATCH
- Capistrano couldn't authenticate, but ssh could
- A Compose volume was hiding my Bundler config
- A missing index, found with rack-mini-profiler
- wkhtmltopdf in an Alpine image
- after_commit and read_changed? never fire together
- Connecting Rails to Amazon RDS with SSL
- Running Rails migrations on an ECS deploy
- Ruby 3.3: the lambda method requires a literal block
- Is this memoization thread safe?
- Building Ruby 3.0.7 on an M2 Mac
- Ruby 2.3 – A Gift for You and Me
- RailsConf 2015, Atlanta Georgia
- Trying out new features of Ruby 2.2
Command line and Git 27
- My guard hook found nc in cancel
- Images in a PR from a fork
- Claude's Bash tool runs my zsh
- A bare wait also waited for tee
- My quick tunnel read my named tunnel's config
- gh as a one-off git credential helper
- chruby picked the broken Ruby
- Three ways Puma didn't restart
- Wrangler used a token I forgot about
- My cd hook was filling Claude's context
- localhost was IPv6 on one end
- Two Ruby managers, one gem directory
- export with no arguments prints everything
- find -path "./node_modules/*" only matches the top level
- A guard hook that errors lets the command run
- Capistrano couldn't authenticate, but ssh could
- Moving Neovim to vim.lsp.enable
- tmux was running as x86 on my M4
- Git doesn't know where a branch came from
- Print only the last block from a log
- In a rebase, ours and theirs swap places
- From a log line to a command on the same box
- An alias can't put arguments in the middle
- fatal: bad revision 'main' in a GitHub Action
- Dear xargs, I appreciate you
- Migrate a Git Repository between Local Machines
- Vim plugins lost in the Vundle
AWS 22
- AWS WAF blocked MCP sign-in from desktop apps
- One distribution, two domains
- ECS stopped tasks that were still booting
- ECS Exec is not a shell
- Logs Insights months start in UTC
- Counting requests per 15 minutes in Logs Insights
- ECS Exec always runs as root
- Docker layer caching in CI, and the tag I overwrote
- SSM stopped working when I removed the public IP
- pulumi import gave me stale code
- TLS from the load balancer to the container
- Connecting Rails to Amazon RDS with SSL
- Running Rails migrations on an ECS deploy
- You can't backdate an S3 object
- Inspector suppression rules update by ARN, not by name
- Packer's env() only works in a variable default
- Mount the partition, not the disk
- Block Public Access wins over a public bucket policy
- From a log line to a command on the same box
- Remote Database Connection via ECS Fargate
- HTTPS For Your Static S3 Website
- Static Website Hosting on Amazon S3
Docker and CI 21
- Old code read what the canary wrote
- YJIT under Rosetta was five times slower
- ECS stopped tasks that were still booting
- compose run used the new image, the server didn't
- Notes from Rails 6.1 to 8.1 in a day
- A frontend deploy broke LLM streaming
- ECS Exec is not a shell
- driven_by replaced my Chrome driver
- WARP blamed 1Password, but Docker was in the way
- Setting config.hosts dropped the defaults
- Time.local doesn't know the Rails zone
- setuptools 82 removed pkg_resources
- Making the Claude GitHub Action open the PR
- There is no author_association on sender
- Deploying a Cloudflare Worker from GitHub Actions
- Postgres in Docker ignored my POSTGRES_ settings
- ECS Exec always runs as root
- A Compose volume was hiding my Bundler config
- Cloud Run job args replace the command
- Docker layer caching in CI, and the tag I overwrote
- wkhtmltopdf in an Alpine image
AI and agents 19
- My guard hook found nc in cancel
- Images in a PR from a fork
- Claude's Bash tool runs my zsh
- A bare wait also waited for tee
- AWS WAF blocked MCP sign-in from desktop apps
- A clean Claude Code inside Claude Code
- gh as a one-off git credential helper
- The caller talked during a tool call
- A frontend deploy broke LLM streaming
- My cd hook was filling Claude's context
- Claude Code kept dropping on my home Wi-Fi
- Claude Desktop started my MCP server with Node 10
- export with no arguments prints everything
- Hanging up is the hard part
- A subagent's model is not the main model
- grammY's bot.start() never returns
- A guard hook that errors lets the command run
- Making the Claude GitHub Action open the PR
- There is no author_association on sender
JavaScript 15
- Where the email link 404s came from
- The caller talked during a tool call
- A frontend deploy broke LLM streaming
- localhost was IPv6 on one end
- One API route on a static Astro site
- Claude Desktop started my MCP server with Node 10
- Hanging up is the hard part
- A subagent's model is not the main model
- Tailwind didn't scan my UI package
- An old PostCSS config broke the Astro build
- grammY's bot.start() never returns
- Deploying a Cloudflare Worker from GitHub Actions
- Bootstrap 2 caps you at jQuery 2
- An axios upgrade dropped my POST body
- A date dropdown that broke two ways
Databases 7
Cloudflare 6
This site 5
Python and data 3
Integrations 3
Rust 1
2026
- My guard hook found nc in cancel
- Images in a PR from a fork
- Claude's Bash tool runs my zsh
- Old code read what the canary wrote
- A bare wait also waited for tee
- AWS WAF blocked MCP sign-in from desktop apps
- YJIT under Rosetta was five times slower
- My quick tunnel read my named tunnel's config
- A clean Claude Code inside Claude Code
- gh as a one-off git credential helper
- One distribution, two domains
- A time on a date column moved the month
- ECS stopped tasks that were still booting
- Two places MySQL wants another layer
- CONVERT TO runs after MODIFY
- chruby picked the broken Ruby
- Three ways Puma didn't restart
- compose run used the new image, the server didn't
- Notes from Rails 6.1 to 8.1 in a day
- Where the email link 404s came from
- Wrangler used a token I forgot about
- A new cookie domain needs a new cookie name
- A hash without braces became keyword arguments
- The caller talked during a tool call
- A frontend deploy broke LLM streaming
- My cd hook was filling Claude's context
- ECS Exec is not a shell
- localhost was IPv6 on one end
- Logs Insights months start in UTC
- 30909 doesn't say what's missing
- driven_by replaced my Chrome driver
- The relation ran after the block ended
- One API route on a static Astro site
- WARP blamed 1Password, but Docker was in the way
- Two Ruby managers, one gem directory
- Claude Code kept dropping on my home Wi-Fi
- Setting config.hosts dropped the defaults
- Time.local doesn't know the Rails zone
- Claude Desktop started my MCP server with Node 10
- export with no arguments prints everything
- Hanging up is the hard part
- Capybara waited for a request my test never checked
- A subagent's model is not the main model
- Tailwind didn't scan my UI package
- find -path "./node_modules/*" only matches the top level
- setuptools 82 removed pkg_resources
- An old PostCSS config broke the Astro build
- grammY's bot.start() never returns
- A guard hook that errors lets the command run
- 633 Worker versions and no way to delete them
- Making the Claude GitHub Action open the PR
- There is no author_association on sender
2025
- nginx returned 405 for PATCH
- Capistrano couldn't authenticate, but ssh could
- Counting requests per 15 minutes in Logs Insights
- Deploying a Cloudflare Worker from GitHub Actions
- Moving Neovim to vim.lsp.enable
- Postgres in Docker ignored my POSTGRES_ settings
- ECS Exec always runs as root
- A Compose volume was hiding my Bundler config
- Cloud Run job args replace the command
- Docker layer caching in CI, and the tag I overwrote
- A missing index, found with rack-mini-profiler
- Bootstrap 2 caps you at jQuery 2
- wkhtmltopdf in an Alpine image
- SSM stopped working when I removed the public IP
- after_commit and read_changed? never fire together
- pulumi import gave me stale code
- TLS from the load balancer to the container
- Connecting Rails to Amazon RDS with SSL
- Running Rails migrations on an ECS deploy
- You can't backdate an S3 object
- Ruby 3.3: the lambda method requires a literal block
- An axios upgrade dropped my POST body
- tmux was running as x86 on my M4
- Inspector suppression rules update by ARN, not by name
2024
- A date dropdown that broke two ways
- Packer's env() only works in a variable default
- Git doesn't know where a branch came from
- Print only the last block from a log
- Is this memoization thread safe?
- In a rebase, ours and theirs swap places
- Mount the partition, not the disk
- Block Public Access wins over a public bucket policy
- From a log line to a command on the same box
- An alias can't put arguments in the middle
- Building Ruby 3.0.7 on an M2 Mac
- fatal: bad revision 'main' in a GitHub Action
2023
- Remote Database Connection via ECS Fargate
- Dear xargs, I appreciate you
- Execute pg_dump against a remote database
- Migrate a Git Repository between Local Machines
- Upgrading a Rust Project
- Becoming Friends with Pandas
- Make Me A Workflow
- Configure Bugsnag to sync with Trello
- Jupyter Notebooks: My New Favorite REPL
- Transitioning to a Notebook-style format