commandcode-api-proxy/src/upstream.ts at main · thaolaptrinh/commandcode-api-proxy · GitHub

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import crypto from "node:crypto";

import { Readable } from "node:stream";

import { parseCCLine } from "@/stream.js";

import type { CCEvent, CCRequestBody } from "@/translate/types.js";

import { logger } from "@/logger.js";

interface UpstreamOptions {

apiBase: string;

apiKey: string;

ccVersion: string;

/** Wall-clock timeout for receiving response headers + first byte. */

timeoutMs?: number;

/** Max ms allowed between consecutive data chunks during streaming. */

idleTimeoutMs?: number;

}

/**

* Build the header set the official Command Code CLI sends. CC's server

* inspects these and rejects requests that look like a proxy ("Proxy use

* detected") if any of the CLI-identifying headers are missing/stale.

export function buildHeaders(

apiKey: string,

ccVersion: string,

body: CCRequestBody,

): Record<string, string> {

const sessionId = body.threadId;

logger.debug(`Sending Authorization header (key length: ${apiKey.length})`);

return {

"Content-Type": "application/json",

Accept: "application/json, */*",

"Accept-Encoding": "gzip, deflate, br",

"Accept-Language": "en-US,en;q=0.9",

Connection: "keep-alive",

"User-Agent": `commandcode-cli/${ccVersion} Node.js/${process.version}`,

Authorization: `Bearer ${apiKey}`,

"x-cli-environment": "production",

"x-command-code-version": ccVersion,

"x-session-id": sessionId,

"x-co-flag": "false",

"x-taste-learning": "false",

"x-project-slug": slugifyWorkingDir(body.config.workingDir as string),

traceparent: generateTraceparent(),

};

}

function slugifyWorkingDir(workingDir: string): string {

const base =

(workingDir || process.cwd()).split(/[/\\]/).filter(Boolean).pop() ?? "commandcode-proxy";

return (

base

.toLowerCase()

.replace(/[^a-z0-9-]/g, "-")

.slice(0, 40) || "commandcode-proxy"

);

}

function generateTraceparent(): string {

const traceId = crypto.randomBytes(16).toString("hex");

const parentId = crypto.randomBytes(8).toString("hex");

return `00-${traceId}-${parentId}-01`;

}

/**

* Send a request to the Command Code /alpha/generate endpoint and parse

* the NDJSON response into CCEvent objects.

* CC's upstream is always streaming; we force `params.stream = true` here

* regardless of the downstream client's `stream` flag. For non-streaming

* downstream requests, the caller drains the returned `stream` into events.

* Retryable failures (HTTP 5xx/429, timeouts, network errors) are retried up

* to MAX_RETRIES times with linear backoff — but ONLY before the stream starts.

* A client-initiated abort (caller already disconnected) is never retried.

* Returns a Readable of parsed CCEvents. Callers MUST consume or destroy it.

const MAX_RETRIES = 2;

const RETRY_BACKOFF_MS = 500;

function sleep(ms: number, signal?: AbortSignal): Promise<void> {

return new Promise((resolve) => {

const t = setTimeout(resolve, ms);

signal?.addEventListener(

"abort",

() => {

clearTimeout(t);

resolve();

{ once: true },

);

});

}

export async function sendToCC(

body: CCRequestBody,

options: UpstreamOptions,

signal?: AbortSignal,

): Promise<{ stream: NodeJS.ReadableStream }> {

const { apiBase, apiKey, ccVersion, timeoutMs = 600_000, idleTimeoutMs = 120_000 } = options;

const url = `${apiBase}/alpha/generate`;

// CC's API is always streaming — force it on so the upstream stays a stream.

body.params.stream = true;

let lastError: UpstreamError | null = null;

for (let attempt = 1; attempt <= MAX_RETRIES + 1; attempt++) {

// Per-attempt timeout so one dead connection can't burn the whole budget.

const controller = new AbortController();

const combinedSignal = signal ? combineSignals(signal, controller.signal) : controller.signal;

const timeout = setTimeout(() => controller.abort(new Error("Upstream timeout")), timeoutMs);

try {

const response = await fetch(url, {

method: "POST",

headers: buildHeaders(apiKey, ccVersion, body),

body: JSON.stringify(body),

signal: combinedSignal,

});

clearTimeout(timeout);

if (!response.ok) {

const errorText = await response.text().catch(() => "");

const retryable = response.status >= 500 || response.status === 429;

lastError = new UpstreamError(

`CC API ${response.status}: ${errorText || response.statusText}`,

response.status,

retryable,

);

if (retryable && attempt <= MAX_RETRIES) {

logger.warn(`CC upstream ${response.status}, retrying ${attempt}/${MAX_RETRIES}...`);

await sleep(RETRY_BACKOFF_MS * attempt, signal);

continue;

}

throw lastError;

}

if (!response.body) {

throw new UpstreamError("CC API returned no body", 0, true);

}

return {

stream: nodeReaderToStream(response.body.getReader(), {

idleTimeoutMs,

abortSignal: signal,

}),

};

} catch (err) {

clearTimeout(timeout);

if (err instanceof UpstreamError) throw err;

// Distinguish a client-initiated abort (caller is gone — never retry, it

// only wastes a request) from a timeout/network blip (retryable).

const aborted = (err as Error).name === "AbortError";

if (aborted && signal?.aborted) {

throw new UpstreamError("Request aborted", 0, true);

}

lastError = new UpstreamError(

aborted ? "Upstream timeout" : `Upstream request failed: ${(err as Error).message}`,

true,

);

if (attempt <= MAX_RETRIES) {

logger.warn(

`CC upstream ${aborted ? "timeout" : "error"}, retrying ${attempt}/${MAX_RETRIES}...`,

);

await sleep(RETRY_BACKOFF_MS * attempt, signal);

continue;

}

throw lastError;

}

throw lastError ?? new UpstreamError("Upstream request failed after retries", 0, true);

}

/**

* Drain a CCEvent stream into an array. Used for non-streaming downstream

* requests where we need the full response before replying.

export function collectEvents(stream: NodeJS.ReadableStream): Promise<CCEvent[]> {

const events: CCEvent[] = [];

return new Promise((resolve, reject) => {

stream.on("data", (event: CCEvent) => events.push(event));

stream.on("end", () => resolve(events));

stream.on("error", reject);

});

}

/**

* Error class for upstream CC API errors.

export class UpstreamError extends Error {

public statusCode: number;

public isRetryable: boolean;

constructor(message: string, statusCode: number, isRetryable: boolean) {

super(message);

this.name = "UpstreamError";

this.statusCode = statusCode;

this.isRetryable = isRetryable;

}

// ──────────────────────────────────────────

// Helpers

// ──────────────────────────────────────────

function combineSignals(...signals: AbortSignal[]): AbortSignal {

const controller = new AbortController();

for (const signal of signals) {

if (signal.aborted) {

controller.abort(signal.reason);

return controller.signal;

}

signal.addEventListener("abort", () => controller.abort(signal.reason), { once: true });

}

return controller.signal;

}

function nodeReaderToStream(

reader: ReadableStreamDefaultReader<Uint8Array>,

opts: { idleTimeoutMs?: number; abortSignal?: AbortSignal } = {},

): NodeJS.ReadableStream {

const decoder = new TextDecoder();

let buffer = "";

// Lines parsed from the current upstream chunk that haven't been pushed yet.

// Kept in closure scope so backpressure mid-chunk doesn't drop them: when

// push() returns false we return out of read(), and resume here on the next

// read() call instead of starting a fresh reader.read().

let pendingLines: string[] = [];

let upstreamDone = false;

let readerReleased = false;

// Idle timeout: detect a stalled upstream (TCP open, no chunks arriving).

// Reset on every successful read(). If it fires we abort the reader so

// pumpStream's error path synthesizes a clean finish for the client

// instead of hanging forever waiting on a dead connection.

const idleMs = opts.idleTimeoutMs ?? 0;

let idleTimer: NodeJS.Timeout | null = null;

const armIdle = (): void => {

if (idleMs <= 0) return;

disarmIdle();

idleTimer = setTimeout(() => {

const err = new Error(`CC upstream idle timeout: no data for ${idleMs}ms`);

err.name = "IdleTimeoutError";

// Cancel the reader — pending read() will reject with this reason.

const cancel = (reader as { cancel?: (reason?: unknown) => Promise<void> }).cancel;

if (typeof cancel === "function") {

cancel.call(reader, err).catch(() => {});

}

}, idleMs);

// Don't keep the event loop alive just for the idle timer.

idleTimer.unref?.();

};

const disarmIdle = (): void => {

if (idleTimer) {

clearTimeout(idleTimer);

idleTimer = null;

}

};

// Release the underlying reader when the consumer destroys this stream

// (e.g. client disconnected). Otherwise CC keeps generating tokens nobody

// will read, burning the user's quota until upstream's own timeout fires.

const releaseReader = (): void => {

disarmIdle();

if (readerReleased) return;

readerReleased = true;

const cancel = (reader as { cancel?: () => Promise<void> }).cancel;

if (typeof cancel === "function") {

cancel.call(reader).catch(() => {

/* already closed */

});

}

};

const stream = new Readable({

objectMode: true,

emitClose: true,

destroy(err, cb) {

releaseReader();

cb(err);

async read() {

try {

while (true) {

// Drain anything left over from a previous chunk that was

// interrupted by backpressure before we read more from upstream.

while (pendingLines.length > 0) {

const line = pendingLines.shift() as string;

const result = parseCCLine(line);

if (result.type === "event" && result.event) {

if (!this.push(result.event)) return; // still backpressured

}

if (upstreamDone) {

this.push(null);

return;

}

armIdle();

const { done, value } = await reader.read();

disarmIdle();

if (done) {

upstreamDone = true;

releaseReader();

// Flush trailing partial line (no newline terminator).

if (buffer.trim()) {

const result = parseCCLine(buffer);

buffer = "";

if (result.type === "event" && result.event) {

if (!this.push(result.event)) return; // backpressured; null next read

}

this.push(null);

return;

}

buffer += decoder.decode(value, { stream: true });

const lines = buffer.split("\n");

// Last segment is the partial line awaiting its newline; keep it.

buffer = lines.pop() ?? "";

pendingLines = lines;

}

} catch (err) {

releaseReader();

this.destroy(err as Error);

}

});

// If the caller aborts (client disconnect), make sure a pending read()

// wakes up. The reader.cancel() in destroy() handles the converse.

if (opts.abortSignal) {

const sig = opts.abortSignal;

if (sig.aborted) {

releaseReader();

} else {

sig.addEventListener(

"abort",

() => {

disarmIdle();

stream.destroy(new Error("Client disconnected"));

{ once: true },

);

}

return stream;

}

commandcode-api-proxy/src/upstream.ts at main · thaolaptrinh/commandcode-api-proxy · GitHub

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