feat(droid): support encrypted auth.v2 file format

extensions/agent-usage/CHANGELOG.md

@@ -1,5 +1,11 @@
 # Agent Usage Changelog
 
+## [Support Droid Encrypted Auth v2] - {PR_MERGE_DATE}
+
+### Improvements
+
+- Support Factory Droid's new encrypted auth v2 format with backward compatibility for legacy auth files
+
 ## [Progress Bars & Zero-Config Auth] - 2026-03-16
 
 ### New Features

extensions/agent-usage/src/droid/auth.ts

@@ -1,8 +1,12 @@
+import * as crypto from "crypto";
 import * as fs from "fs";
 import * as os from "os";
 import * as path from "path";
 
-const AUTH_PATHS = [
+const AUTH_V2_FILE = path.join(os.homedir(), ".factory", "auth.v2.file");
+const AUTH_V2_KEY = path.join(os.homedir(), ".factory", "auth.v2.key");
+
+const AUTH_LEGACY_PATHS = [
   path.join(os.homedir(), ".factory", "auth.json"),
   path.join(os.homedir(), ".factory", "auth.encrypted"),
 ];
@@ -89,6 +93,11 @@ async function refreshAccessToken(refreshToken: string): Promise<AuthTokens | nu
 
 function saveAuthToFile(filePath: string, tokens: AuthTokens): void {
   try {
+    if (filePath === AUTH_V2_FILE) {
+      saveAuthV2(tokens);
+      return;
+    }
+
     let existing: Record<string, unknown> = {};
     if (fs.existsSync(filePath)) {
       const raw = fs.readFileSync(filePath, "utf-8");
@@ -116,8 +125,69 @@ function saveAuthToFile(filePath: string, tokens: AuthTokens): void {
   }
 }
 
+function saveAuthV2(tokens: AuthTokens): void {
+  try {
+    if (!fs.existsSync(AUTH_V2_KEY)) return;
+
+    const keyB64 = fs.readFileSync(AUTH_V2_KEY, "utf-8").trim();
+    const key = Buffer.from(keyB64, "base64");
+    const iv = crypto.randomBytes(16);
+    const cipher = crypto.createCipheriv("aes-256-gcm", key, iv);
+
+    const plaintext = JSON.stringify({
+      access_token: tokens.access_token,
+      refresh_token: tokens.refresh_token,
+    });
+
+    let encrypted = cipher.update(plaintext, "utf-8");
+    encrypted = Buffer.concat([encrypted, cipher.final()]);
+    const tag = cipher.getAuthTag();
+
+    const content = [iv.toString("base64"), tag.toString("base64"), encrypted.toString("base64")].join(":");
+    fs.writeFileSync(AUTH_V2_FILE, content, "utf-8");
+  } catch {
+    // best-effort
+  }
+}
+
+function tryParseAuthV2(): { tokens: AuthTokens; filePath: string } | null {
+  try {
+    if (!fs.existsSync(AUTH_V2_FILE) || !fs.existsSync(AUTH_V2_KEY)) return null;
+
+    const keyB64 = fs.readFileSync(AUTH_V2_KEY, "utf-8").trim();
+    const fileContent = fs.readFileSync(AUTH_V2_FILE, "utf-8").trim();
+
+    const parts = fileContent.split(":");
+    if (parts.length !== 3) return null;
+
+    const key = Buffer.from(keyB64, "base64");
+    const iv = Buffer.from(parts[0], "base64");
+    const tag = Buffer.from(parts[1], "base64");
+    const ciphertext = Buffer.from(parts[2], "base64");
+
+    const decipher = crypto.createDecipheriv("aes-256-gcm", key, iv);
+    decipher.setAuthTag(tag);
+    let decrypted = decipher.update(ciphertext, undefined, "utf-8");
+    decrypted += decipher.final("utf-8");
+
+    const parsed = JSON.parse(decrypted) as Record<string, unknown>;
+    const accessToken = (parsed.access_token ?? parsed.accessToken) as string | undefined;
+    const refreshToken = (parsed.refresh_token ?? parsed.refreshToken) as string | undefined;
+
+    if (!accessToken) return null;
+    return { tokens: { access_token: accessToken, refresh_token: refreshToken ?? null }, filePath: AUTH_V2_FILE };
+  } catch {
+    return null;
+  }
+}
+
 function loadAuthFromFiles(): AuthState | null {
-  for (const filePath of AUTH_PATHS) {
+  // Try v2 encrypted format first
+  const v2 = tryParseAuthV2();
+  if (v2) return { tokens: v2.tokens, source: "file", filePath: v2.filePath };
+
+  // Fall back to legacy plain-text files
+  for (const filePath of AUTH_LEGACY_PATHS) {
     const tokens = tryParseAuthFile(filePath);
     if (tokens) return { tokens, source: "file", filePath };
   }

extensions/agent-usage/src/droid/fetcher.ts

@@ -90,7 +90,8 @@ export function useDroidUsage(enabled = true) {
       setUsage(null);
       setError({
         type: "not_configured",
-        message: "Droid not configured. Run `droid` to log in (auto-detected from ~/.factory/auth.*).",
+        message:
+          "Droid not configured. Run `droid` to log in (auto-detected from ~/.factory/auth.v2.* or ~/.factory/auth.*).",
       });
       setIsLoading(false);
       setHasInitialFetch(true);