Simon Willison released llm-keys-ui because he refuses to paste API keys into agent sessions.

The plugin launches a local web server via uvx --with llm-keys-ui llm keys-ui --all, lets you add keys through a browser form, never displays existing values, and lets an agent retrieve them later with llm keys get anthropic inside a shell command. He shipped it after starting to drive coding agents on remote machines from his phone. The stated reason is the pattern: keys go in through a channel the agent transcript never sees, and come out through a command the agent runs but can't read the output of.