pi-anthropic-web-fetch

Anthropic native web fetch extension for the pi coding agent.

This package is the standalone extraction of senpi's former builtin anthropic-web-fetch extension.

Behavior

The extension does not register a new tool. It intercepts Anthropic requests before they are sent and ensures a native web_fetch_* tool is present for anthropic-messages payloads.

Case	Result
API is anthropic-messages and no native web_fetch_* tool exists	injects { type: "web_fetch_20260309", name: "web_fetch" }
Existing native web_fetch_* tool exists	preserves it (no duplication)
Function variants named webfetch or web_fetch are present	strips function variants and keeps native variant
Non-Anthropic API payload	leaves payload unchanged

Set PI_ANTHROPIC_WEB_FETCH_MAX_USES (positive integer) to include max_uses on injected native web-fetch tools.

It also appends a system-prompt section for Anthropic sessions indicating native web_fetch availability.

Installation

The package targets the pi coding agent. Pi loads extensions from ~/.pi/agent/extensions/, project .pi/extensions/, or via the --extension / -e CLI flag.

# From npm (once published)
pi install npm:pi-anthropic-web-fetch

# From git
pi install git:github.com/code-yeongyu/pi-anthropic-web-fetch

# Manual placement
git clone https://github.com/code-yeongyu/pi-anthropic-web-fetch ~/.pi/agent/extensions/pi-anthropic-web-fetch
cd ~/.pi/agent/extensions/pi-anthropic-web-fetch && npm install

# Dev / one-shot test
pi -e /path/to/pi-anthropic-web-fetch/src/index.ts

After installation, restart pi or run /reload inside an interactive session.

Development

npm install
npm test
npm run typecheck
npm run check
pi -e ./src/index.ts

The test suite uses vitest. TypeScript is strict, Node-only, and uses ESM imports with .js suffixes.

Origin

Ported from packages/coding-agent/src/core/extensions/builtin/anthropic-web-fetch/index.ts in code-yeongyu/senpi-mono.

License

MIT.

Related

• senpi — the fork/runtime these extensions are extracted from.
• Ultraworkers Discord — community link from the senpi README.
• Dori — the product powered by senpi under the hood.