pxpipe-go

A Go port of the core of pxpipe. It converts large system prompts, tool definitions, earlier conversation turns, and tool results into dense PNG pages when the vision input is estimated to cost fewer tokens than the source text.

The transform supports Anthropic Messages, OpenAI Chat Completions, and OpenAI Responses request bodies. The Gemini/Google API surface, upstream dashboard, and offline export CLI are not included.

Interfaces

Interface	Entry point	Use case
CLI wrapper	pxpipe <executable>	Run Claude Code, Claude Desktop, OpenCode, or Codex through a process-scoped proxy
Standalone proxy	pxpipe serve	Connect an existing client to a loopback reverse/forward proxy
Go package	pxpipe.NewHandler and transform functions	Embed the proxy or request transform in a Go server

Installation

pxpipe-go requires Go 1.26.3 or later.

go install github.com/evan-choi/pxpipe-go/cmd/pxpipe@v0.4.19
pxpipe --version

go install writes the binary to go env GOBIN, or to $(go env GOPATH)/bin when GOBIN is unset. Add that directory to PATH if needed.

Add the Go package to a module with:

go get github.com/evan-choi/pxpipe-go@v0.4.19

Quick start

CLI wrapper

pxpipe claude --model opus
pxpipe Claude.app
PXPIPE_MODELS=gpt-5.6-sol pxpipe opencode --model openai/gpt-5.6-sol
PXPIPE_MODELS=gpt-5.6-sol pxpipe codex --model gpt-5.6-sol

Arguments after the executable are passed to the child unchanged. Proxy and local CA settings apply only to the child; pxpipe does not modify the system trust store. A Codex provider must set supports_websockets=false so request bodies use HTTP and can be transformed.

Standalone proxy

pxpipe serve
pxpipe serve --port 8080

The default port is 47821. The startup view prints ready-to-run Claude and Codex commands. The Codex command includes the generated CA path and proxy environment.

ANTHROPIC_BASE_URL=http://localhost:47821 claude

Go reverse proxy

NewHandler forwards to the public Anthropic and OpenAI APIs by default.

package main

import (
	"log"
	"net/http"

	pxpipe "github.com/evan-choi/pxpipe-go"
)

func main() {
	handler := pxpipe.NewHandler(pxpipe.HandlerOptions{})
	log.Fatal(http.ListenAndServe("127.0.0.1:47821", handler))
}

Point Claude Code at the handler:

ANTHROPIC_BASE_URL=http://127.0.0.1:47821 claude

See the usage reference for custom upstreams, route mapping, credential injection, and pure transforms.

Model configuration

Setting	Behavior
PXPIPE_MODELS	CSV list of model base IDs to transform; models outside the list pass through unchanged
PXPIPE_GPT_PROFILES	JSON profiles for GPT-compatible models not in the built-in table
PXPIPE_RENDER_CACHE_BYTES	Render cache capacity; defaults to 64 MiB, and 0 disables it

The library and CLI wrapper have a built-in allowlist of claude-fable-5 and gemini-3.6-flash; GPT models are opt-in. pxpipe serve accepts every valid Anthropic and OpenAI model when PXPIPE_MODELS is empty.

Documentation

• Usage reference: CLI profiles, standalone proxy, Go handler, and pure transforms
• Performance and compatibility: golden parity, benchmarks, and reproduction commands
• Upstream port status: pinned revision, port scope, and fixture verification

Performance

On an Apple M1 Pro, the four measured workloads ran 72.6–282.2 times faster than the TypeScript implementation, while peak RSS for the full suite was 73.4% lower. See performance and compatibility for the measurement conditions.

Verification

Golden fixtures come only from the pinned TypeScript implementation. Tests compare text, gate decisions, page geometry, and decoded pixels.

go test ./...

License

MIT. Portions derived from teamchong/pxpipe (MIT).