@jovan158/vantage/dist/dev/mock-anthropic.js

See and control what your coding agent does

// Minimal mock of api.anthropic.com's POST /v1/messages streaming endpoint,
// shared by the test suite and `vantage demo`. Lets the full chain run with no
// API key and no network egress.
import http from "node:http";
export const EXPECTED_USAGE = {
    model: "claude-sonnet-5",
    input_tokens: 1024,
    cache_read_input_tokens: 512,
    cache_creation_input_tokens: 0,
    output_tokens: 87,
};
function buildSseFrames() {
    const f = [];
    const push = (event, data) => f.push(`event: ${event}\ndata: ${JSON.stringify(data)}\n\n`);
    push("message_start", {
        type: "message_start",
        message: {
            id: "msg_demo_001",
            type: "message",
            role: "assistant",
            model: EXPECTED_USAGE.model,
            content: [],
            stop_reason: null,
            usage: {
                input_tokens: EXPECTED_USAGE.input_tokens,
                cache_creation_input_tokens: 0,
                cache_read_input_tokens: EXPECTED_USAGE.cache_read_input_tokens,
                output_tokens: 1,
            },
        },
    });
    push("content_block_start", {
        type: "content_block_start",
        index: 0,
        content_block: { type: "text", text: "" },
    });
    for (const piece of ["Hello", ", ", "world", "!"]) {
        push("content_block_delta", {
            type: "content_block_delta",
            index: 0,
            delta: { type: "text_delta", text: piece },
        });
    }
    push("content_block_stop", { type: "content_block_stop", index: 0 });
    push("message_delta", {
        type: "message_delta",
        delta: { stop_reason: "end_turn", stop_sequence: null },
        usage: { output_tokens: EXPECTED_USAGE.output_tokens },
    });
    push("message_stop", { type: "message_stop" });
    return f;
}
export function startMockAnthropic(port = 0) {
    const frames = buildSseFrames();
    const fullBody = Buffer.from(frames.join(""), "utf8");
    const server = http.createServer((req, res) => {
        if (req.method !== "POST" || !(req.url ?? "").startsWith("/v1/messages")) {
            res.writeHead(404);
            res.end("not found");
            return;
        }
        res.writeHead(200, {
            "content-type": "text/event-stream; charset=utf-8",
            "cache-control": "no-cache",
            connection: "keep-alive",
        });
        let i = 0;
        const tick = () => {
            if (i >= frames.length) {
                res.end();
                return;
            }
            res.write(frames[i++]);
            setTimeout(tick, 5);
        };
        tick();
    });
    return new Promise((resolve) => {
        server.listen(port, "127.0.0.1", () => {
            const addr = server.address();
            resolve({
                server,
                port: addr.port,
                url: `http://127.0.0.1:${addr.port}`,
                fullBody,
                close: () => new Promise((r) => server.close(() => r())),
            });
        });
    });
}