The coding agent just became a middleware stack. anthropic shipped mods on oct 1, letting…
the coding agent just became a middleware stack. anthropic shipped mods on oct 1, letting typescript functions hook into claude code's loop to rewrite prompts, block tool calls, and swap built-in features.
the agent is now an express server.
Context
Anthropic introduced mods on Oct 1, 2026: small TypeScript functions that change how Claude Code works. A mod can rewrite a prompt, add UI, replace a built-in feature or add new functionality, and mods ship inside plugins.
The Claude Code docs describe hooks as event handlers that can observe, rewrite or answer tool calls, prompts and turns.
Mods as TypeScript functions that rewrite prompts and replace built-in features match Anthropic's post. The docs say hooks can observe, rewrite or answer tool calls; 'block tool calls' as worded was not seen in the excerpts read, so unsupported here, not refuted.
'the agent is now an express server' is the author's opinion.
Related work
- Claude: Customize Claude Code with mods in TypeScript ↗Launch article.
- Claude Code Docs: React to events with a mod ↗Hook events.
- GitHub: Mods, make Claude 10x more extensible (issue 91870) ↗Origin of the feature.
Watch next
- Read the mods reference for the full event list.
Sources
- Claude, Oct 1, 2026claude.com
- Claude Code Docs, mod eventscode.claude.com
- anthropics/claude-code issue 91870github.com
Provenance
The note above is reproduced unedited from the original post, first published on Threads on 11 October 2026 at 01:16 IST. Sources are the papers and datasets the note draws on.
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