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fix(disguise): realign to genuine Claude Code 2.1.205 to defeat new extra-usage detection #61

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fix(disguise): realign to genuine Claude Code 2.1.205 to defeat new extra-usage detection #61

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68 changes: 52 additions & 16 deletions proxy.js
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Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,12 @@ const UPSTREAM_HOST = 'api.anthropic.com';
const VERSION = '2.2.3';

// Claude Code version to emulate (update when new CC versions are released)
const CC_VERSION = '2.1.97';
const CC_VERSION = '2.1.205';

// Last upstream request-id, used to emit the modern `cc_prev_req` billing-header
// chain field that real CC 2.1.205 sends on first-party requests. Genuine sessions
// chain consecutive requests; a static header that never chains is a detection tell.
let LAST_REQUEST_ID = null;

// Billing fingerprint constants (matches real CC utils/fingerprint.ts)
const BILLING_HASH_SALT = '59cf53e54c78';
Expand All @@ -46,17 +51,31 @@ const BILLING_HASH_INDICES = [4, 7, 20];
// Persistent per-instance identifiers (generated once at startup)
const DEVICE_ID = crypto.randomBytes(32).toString('hex');
const INSTANCE_SESSION_ID = crypto.randomUUID();
// Real account UUID for this OAuth identity (genuine CC includes it in
// metadata.user_id; its absence is a detection tell). Kept out of source:
// set via CC_ACCOUNT_UUID env or `account_uuid` in the gitignored config.json.
let ACCOUNT_UUID = process.env.CC_ACCOUNT_UUID || '';
try {
if (!ACCOUNT_UUID) {
ACCOUNT_UUID = (JSON.parse(require('fs').readFileSync(require('path').join(__dirname, 'config.json'), 'utf8')).account_uuid) || '';
}
} catch (e) {}

// Beta flags required for OAuth + Claude Code features
// Beta flags — EXACT list + order captured from genuine Claude Code 2.1.205
// (via capture proxy, 2026-07-16). Must match verbatim; the set/order is a
// fingerprint. Genuine CC replaces the beta header wholesale, so we override.
const REQUIRED_BETAS = [
'oauth-2025-04-20',
'claude-code-20250219',
'oauth-2025-04-20',
'interleaved-thinking-2025-05-14',
'advanced-tool-use-2025-11-20',
'thinking-token-count-2026-05-13',
'context-management-2025-06-27',
'prompt-caching-scope-2026-01-05',
'mid-conversation-system-2026-04-07',
'advisor-tool-2026-03-01',
'advanced-tool-use-2025-11-20',
'effort-2025-11-24',
'fast-mode-2026-02-01'
'extended-cache-ttl-2025-04-11'
];

// CC tool stubs -- injected into tools array to make the tool set look more
Expand Down Expand Up @@ -127,25 +146,33 @@ function buildBillingBlock(bodyStr) {
const firstText = extractFirstUserText(bodyStr);
const fingerprint = computeBillingFingerprint(firstText);
const ccVersion = `${CC_VERSION}.${fingerprint}`;
return `{"type":"text","text":"x-anthropic-billing-header: cc_version=${ccVersion}; cc_entrypoint=cli; cch=00000;"}`;
// Modern CC (2.1.205) assembles: cc_version=..; cc_entrypoint=..; cch=00000; [ cc_prev_req=<id>;]
// The prev-request chain is only present once there is a prior request (first-party).
const prev = LAST_REQUEST_ID ? ` cc_prev_req=${LAST_REQUEST_ID};` : '';
// Genuine 2.1.205 (sdk-cli mode, captured 2026-07-16) emits exactly:
// "x-anthropic-billing-header: cc_version=<v.fp>; cc_entrypoint=sdk-cli;"
// No cch field in this mode. Entrypoint must match the user-agent's (sdk-cli).
return `{"type":"text","text":"x-anthropic-billing-header: cc_version=${ccVersion}; cc_entrypoint=sdk-cli;${prev}"}`;
}

// ─── Stainless SDK Headers ──────────────────────────────────────────────────
// Real Claude Code sends these on every request via the Anthropic JS SDK.
function getStainlessHeaders() {
const p = process.platform;
const osName = p === 'darwin' ? 'macOS' : p === 'win32' ? 'Windows' : p === 'linux' ? 'Linux' : p;
// Genuine CC reports 'MacOS' (capital OS), not Node's 'macOS' — casing is a tell.
const osName = p === 'darwin' ? 'MacOS' : p === 'win32' ? 'Windows' : p === 'linux' ? 'Linux' : p;
const arch = process.arch === 'x64' ? 'x64' : process.arch === 'arm64' ? 'arm64' : process.arch;
// All values below captured verbatim from genuine CC 2.1.205 (sdk-cli, 2026-07-16).
return {
'user-agent': `claude-cli/${CC_VERSION} (external, cli)`,
'user-agent': `claude-cli/${CC_VERSION} (external, sdk-cli)`,
'x-app': 'cli',
'x-claude-code-session-id': INSTANCE_SESSION_ID,
'x-stainless-arch': arch,
'x-stainless-lang': 'js',
'x-stainless-os': osName,
'x-stainless-package-version': '0.81.0',
'x-stainless-package-version': '0.94.0',
'x-stainless-runtime': 'node',
'x-stainless-runtime-version': process.version,
'x-stainless-runtime-version': 'v26.3.0',
'x-stainless-retry-count': '0',
'x-stainless-timeout': '600',
'anthropic-dangerous-direct-browser-access': 'true'
Expand Down Expand Up @@ -649,7 +676,8 @@ function processBody(bodyStr, config) {

// Metadata injection: device_id + session_id matching real CC format
// Uses raw string manipulation to inject/replace metadata field
const metaValue = JSON.stringify({ device_id: DEVICE_ID, session_id: INSTANCE_SESSION_ID });
// Genuine metadata.user_id includes account_uuid between device_id and session_id.
const metaValue = JSON.stringify({ device_id: DEVICE_ID, account_uuid: ACCOUNT_UUID, session_id: INSTANCE_SESSION_ID });
const metaJson = '"metadata":{"user_id":' + JSON.stringify(metaValue) + '}';
const existingMeta = m.indexOf('"metadata":{');
if (existingMeta !== -1) {
Expand Down Expand Up @@ -811,20 +839,28 @@ function startServer(config) {
headers[k] = v;
}

const existingBeta = headers['anthropic-beta'] || '';
const betas = existingBeta ? existingBeta.split(',').map(b => b.trim()) : [];
for (const b of REQUIRED_BETAS) { if (!betas.includes(b)) betas.push(b); }
headers['anthropic-beta'] = betas.join(',');
// Override wholesale with the genuine list/order — a merged set that keeps
// OpenClaw-specific betas (or reorders) is itself a fingerprint.
headers['anthropic-beta'] = REQUIRED_BETAS.join(',');

const ts = new Date().toISOString().substring(11, 19);
console.log(`[${ts}] #${reqNum} ${req.method} ${req.url} (${originalSize}b -> ${body.length}b)`);

// Genuine CC posts to /v1/messages?beta=true — ensure the query param is present.
let upstreamPath = req.url;
if (upstreamPath.startsWith('/v1/messages') && !/[?&]beta=true/.test(upstreamPath)) {
upstreamPath += (upstreamPath.includes('?') ? '&' : '?') + 'beta=true';
}

const upstream = https.request({
hostname: UPSTREAM_HOST, port: 443,
path: req.url, method: req.method, headers
path: upstreamPath, method: req.method, headers
}, (upRes) => {
const status = upRes.statusCode;
console.log(`[${ts}] #${reqNum} > ${status}`);
// Track upstream request-id to chain the next request's cc_prev_req header.
const rid = upRes.headers['request-id'] || upRes.headers['anthropic-request-id'];
if (rid) LAST_REQUEST_ID = rid;
if (status !== 200 && status !== 201) {
const errChunks = [];
upRes.on('data', c => errChunks.push(c));
Expand Down