WebAssembly/JS bindings for the llmtrim-core compression engine, for running the static prompt/payload compressor in a browser, Node, Bun, Deno, or a Cloudflare Worker. No network or filesystem access.

Published to npm as @llmtrim/js (with @llmtrim/wasm as an alias that re-exports the same package).

API

import { compress } from "@llmtrim/js";

const out = compress(requestBodyJson, "openai", "agent");
// out: CompressOutput { request_json, provider, model, tokenizer_label,
//   tokenizer_exact, input_tokens_before, input_tokens_after,
//   frozen_input_tokens, output_shaped, stages: StageReport[] }

provider: "openai" | "anthropic" | "google", or undefined/null to auto-detect from the body.
preset: a named workload preset (aggressive, agent, code, rag, safe, …), or undefined/null for the built-in defaults. This binding never reads the environment or a config file.

TypeScript types for CompressOutput and StageReport are generated via tsify, so the .d.ts is fully typed (no any).

This build links llmtrim-core with default-features = false: the estimate tokenizer is used (counts are approximate; savings percentages are unchanged), and code skeletonization and image downscaling are no-ops. That keeps the bundle small (~1 MB gzipped, under the Cloudflare Workers 3 MB free-tier cap).

Building

The npm package is built in CI with wasm-pack build --target bundler (it manages a matching wasm-bindgen internally). The manual cargo + wasm-bindgen recipe below is the equivalent for local development:

rustup target add wasm32-unknown-unknown
cargo install wasm-bindgen-cli

# The JS-backed getrandom backend needs a rustc cfg in the environment (it cannot live in a
# repo .cargo/config.toml, which would break `cargo publish`).
RUSTFLAGS='--cfg getrandom_backend="wasm_js"' \
  cargo build -p llmtrim-wasm --release --target wasm32-unknown-unknown

wasm-bindgen target/wasm32-unknown-unknown/release/llmtrim_wasm.wasm \
  --out-dir pkg --target bundler   # or: nodejs | web

# optional size pass
wasm-opt -O3 --enable-reference-types --enable-bulk-memory --enable-mutable-globals \
  --enable-nontrapping-float-to-int --enable-sign-ext --enable-multivalue \
  pkg/llmtrim_wasm_bg.wasm -o pkg/llmtrim_wasm_bg.wasm

Smoke test

After building with --target nodejs into pkg/, run node smoke.mjs (it imports ./pkg/llmtrim_wasm.js). It exercises OpenAI and Anthropic requests, a named preset, an error path, and non-ASCII (CJK) input.