@dwk/esi

Streaming Edge Side Includes (ESI) processor for a composed Worker's outgoing Response, so a mostly-static, edge-cacheable shell can splice in live fragments at request time.

Supports a pragmatic v1 subset of three tags:

• <esi:include src="…" alt="…"? onerror="continue"?/> — fetch src (through @dwk/safe-fetch) and splice the fragment body in place.
• <esi:comment text="…"/> — no-op, removed from output.
• <esi:remove>…</esi:remove> — the block and its contents are stripped from output entirely.

See docs/superpowers/specs/2026-07-13-esi-design.md for the full design rationale.

Usage

import { processEsi } from "@dwk/esi";

export default {
  async fetch(request: Request, env: Env, ctx: ExecutionContext) {
    const shell = await buildShellResponse(request, env);
    return processEsi(shell, { baseUrl: request.url });
  },
};