Claude Code Mods: reprogram your coding agent in TypeScript
The agent is now scriptable—rewrite prompts, add UI, spawn sub-agents—and the Oct 4 build adds multi-agent orchestration, as OpenAI sunsets three models.
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Mods let you reprogram Claude Code
Mods are TypeScript functions that can “rewrite a prompt, add new UI, replace a built-in feature, or add entirely new functionality.” Your coding agent becomes a platform you extend—build the exact workflow your repo needs instead of waiting for a shipped feature.
Spawn and inspect sub-agents from a mod
The Oct 4 build (2.1.289) adds agent.spawn for teammates plus agent state in $.agent.list(), after 2.1.288 added $.ui.selection() to read selected text. You can script multi-agent runs and custom panes without leaving the CLI.
‘You should know’ flags what you missed
A built-in mod runs a side agent that surfaces items you overlooked mid-task—a free safety net on long agentic sessions, and a working template for writing your own monitor mod.
OpenAI sets an April 2027 sunset for three models
gpt-5.1, gpt-5.3-codex, and gpt-5.4-nano are now deprecated with an April 1, 2027 shutoff; migrate to gpt-6-sol and gpt-6-luna. Pin the date now if any of them run in your pipeline.