refactor(FN-1616): convert blocking fs operations to async on HTTP request paths

- Convert skills-adapter.ts readFileSync/writeFileSync to async readFile/writeFile
- Cache GitHub webhook private key in memory to avoid repeated fs reads
- Convert usage.ts readFileSync to async readFile
- Update usage.test.ts to work with async file operations
- All HTTP request handlers now use non-blocking async fs operations

packages/dashboard/src/github-webhooks.ts

@@ -3,6 +3,17 @@ import { readFileSync } from "node:fs";
 import type { IssueInfo, PrInfo } from "@fusion/core";
 import { GitHubClient } from "./github.js";
 
+// Module-level cache for the GitHub App private key
+// undefined = not yet read, null = read failed, string = cached key
+let cachedPrivateKey: string | null | undefined = undefined;
+
+/**
+ * Clear the private key cache (for testing).
+ */
+export function _clearPrivateKeyCache(): void {
+  cachedPrivateKey = undefined;
+}
+
 /**
  * GitHub App webhook configuration from environment variables.
  */
@@ -64,16 +75,20 @@ export function getGitHubAppConfig(): GitHubAppConfig | null {
   const webhookSecret = process.env.FUSION_GITHUB_WEBHOOK_SECRET;
 
   let privateKey: string | undefined;
-  
+
   if (process.env.FUSION_GITHUB_APP_PRIVATE_KEY) {
     privateKey = process.env.FUSION_GITHUB_APP_PRIVATE_KEY;
   } else if (process.env.FUSION_GITHUB_APP_PRIVATE_KEY_PATH) {
-    try {
-      privateKey = readFileSync(process.env.FUSION_GITHUB_APP_PRIVATE_KEY_PATH, "utf-8");
-    } catch {
-      // Failed to read key file
-      return null;
+    // Check cache before reading from disk
+    if (cachedPrivateKey === undefined) {
+      try {
+        cachedPrivateKey = readFileSync(process.env.FUSION_GITHUB_APP_PRIVATE_KEY_PATH, "utf-8");
+      } catch {
+        // Failed to read key file
+        cachedPrivateKey = null;
+      }
     }
+    privateKey = cachedPrivateKey ?? undefined;
   }
 
   if (!appId || !privateKey || !webhookSecret) {

packages/dashboard/src/skills-adapter.ts

@@ -5,7 +5,8 @@
  * by integrating with the pi-coding-agent package manager and skills.sh API.
  */
 
-import { readFileSync, writeFileSync, existsSync, mkdirSync } from "node:fs";
+import { existsSync } from "node:fs";
+import { readFile, writeFile, mkdir } from "node:fs/promises";
 import { join, relative, dirname } from "node:path";
 
 /**
@@ -216,7 +217,7 @@ export function createSkillsAdapter(options: {
       let settings: { skills?: string[]; packages?: unknown[] } = {};
       if (existsSync(settingsPath)) {
         try {
-          settings = JSON.parse(readFileSync(settingsPath, "utf-8")) as typeof settings;
+          settings = JSON.parse(await readFile(settingsPath, "utf-8")) as typeof settings;
         } catch {
           // Ignore parse errors
         }
@@ -272,13 +273,13 @@ export function createSkillsAdapter(options: {
       const settingsPath = options.getSettingsPath(rootDir);
       const settingsDir = dirname(settingsPath);
       if (!existsSync(settingsDir)) {
-        mkdirSync(settingsDir, { recursive: true });
+        await mkdir(settingsDir, { recursive: true });
       }
 
       let settings: Record<string, unknown> = {};
       if (existsSync(settingsPath)) {
         try {
-          settings = JSON.parse(readFileSync(settingsPath, "utf-8")) as Record<string, unknown>;
+          settings = JSON.parse(await readFile(settingsPath, "utf-8")) as Record<string, unknown>;
         } catch {
           // Start fresh on parse error
         }
@@ -314,7 +315,7 @@ export function createSkillsAdapter(options: {
 
         settings.skills = skills;
 
-        writeFileSync(settingsPath, JSON.stringify(settings, null, 2));
+        await writeFile(settingsPath, JSON.stringify(settings, null, 2));
         return {
           settingsPath: "skills",
           pattern: `${prefix}${skillPath}`,
@@ -366,7 +367,7 @@ export function createSkillsAdapter(options: {
         pkgEntry.skills.push(`${prefix}${skillPath}`);
 
         settings.packages = packages;
-        writeFileSync(settingsPath, JSON.stringify(settings, null, 2));
+        await writeFile(settingsPath, JSON.stringify(settings, null, 2));
         return {
           settingsPath: "packages[].skills",
           pattern: `${prefix}${skillPath}`,
@@ -578,12 +579,12 @@ function normalizeEntry(entry: unknown): CatalogEntry {
 /**
  * Read project settings from .fusion/settings.json.
  */
-export function readProjectSettings(projectPath: string): Record<string, unknown> {
+export async function readProjectSettings(projectPath: string): Promise<Record<string, unknown>> {
   const fusionSettings = join(projectPath, ".fusion", "settings.json");
 
   if (existsSync(fusionSettings)) {
     try {
-      return JSON.parse(readFileSync(fusionSettings, "utf-8")) as Record<string, unknown>;
+      return JSON.parse(await readFile(fusionSettings, "utf-8")) as Record<string, unknown>;
     } catch {
       // Return empty on parse error
     }
@@ -595,15 +596,15 @@ export function readProjectSettings(projectPath: string): Record<string, unknown
 /**
  * Write project settings to .fusion/settings.json atomically.
  */
-export function writeProjectSettings(projectPath: string, settings: Record<string, unknown>): void {
+export async function writeProjectSettings(projectPath: string, settings: Record<string, unknown>): Promise<void> {
   const settingsDir = join(projectPath, ".fusion");
   const settingsPath = join(settingsDir, "settings.json");
 
   if (!existsSync(settingsDir)) {
-    mkdirSync(settingsDir, { recursive: true });
+    await mkdir(settingsDir, { recursive: true });
   }
 
-  writeFileSync(settingsPath, JSON.stringify(settings, null, 2));
+  await writeFile(settingsPath, JSON.stringify(settings, null, 2));
 }
 
 /**

packages/dashboard/src/usage.test.ts

@@ -22,10 +22,11 @@ vi.mock("node:https", () => ({
   request: (...args: any[]) => mockRequest(...args),
 }));
 
-// Mock fs
-const mockReadFileSync = vi.fn();
-vi.mock("node:fs", () => ({
-  readFileSync: (...args: any[]) => mockReadFileSync(...args),
+// Mock fs/promises
+const mockReadFile = vi.fn();
+vi.mock("node:fs/promises", () => ({
+  readFile: (...args: any[]) => mockReadFile(...args),
+  default: { readFile: (...args: any[]) => mockReadFile(...args) },
 }));
 
 // Mock child_process
@@ -53,7 +54,7 @@ describe("usage", () => {
     clearUsageCache();
     _clearRefreshedToken();
     mockRequest.mockClear();
-    mockReadFileSync.mockClear();
+    mockReadFile.mockClear();
     mockExecFileSync.mockClear();
     vi.stubEnv("HOME", "/home/testuser");
   });
@@ -65,8 +66,8 @@ describe("usage", () => {
   describe("fetchAllProviderUsage", () => {
     it("returns providers array even when all are not authenticated", async () => {
       // All credential files don't exist
-      mockReadFileSync.mockImplementation(() => {
-        throw new Error("File not found");
+      mockReadFile.mockImplementation(async () => {
+        return Promise.reject(new Error("File not found"));
       });
 
       const providers = await fetchAllProviderUsage();
@@ -87,8 +88,8 @@ describe("usage", () => {
     });
 
     it("returns cached data within TTL", async () => {
-      mockReadFileSync.mockImplementation(() => {
-        throw new Error("File not found");
+      mockReadFile.mockImplementation(async () => {
+        return Promise.reject(new Error("File not found"));
       });
 
       const first = await fetchAllProviderUsage();
@@ -99,8 +100,8 @@ describe("usage", () => {
     });
 
     it("fetches fresh data after cache expires", async () => {
-      mockReadFileSync.mockImplementation(() => {
-        throw new Error("File not found");
+      mockReadFile.mockImplementation(async () => {
+        return Promise.reject(new Error("File not found"));
       });
 
       const first = await fetchAllProviderUsage();
@@ -129,11 +130,11 @@ describe("usage", () => {
     }) {
       const { credFileContent = null, keychainContent = null } = options;
 
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes("claude") && credFileContent !== null) {
           return JSON.stringify(credFileContent);
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
 
       mockExecFileSync.mockImplementation((cmd: string, _args: string[]) => {
@@ -177,8 +178,8 @@ describe("usage", () => {
     }
 
     it("detects no auth when credentials file doesn't exist and keychain fails", async () => {
-      mockReadFileSync.mockImplementation(() => {
-        throw new Error("File not found");
+      mockReadFile.mockImplementation(async () => {
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -255,14 +256,14 @@ describe("usage", () => {
     });
 
     it("detects missing scope error", async () => {
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes("claude")) {
           return JSON.stringify({
             accessToken: "test-token",
             scopes: ["other:scope"], // missing user:profile
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -450,14 +451,14 @@ describe("usage", () => {
         five_hour: { utilization: 10.0 },
       };
 
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("claude")) {
           return JSON.stringify({
             accessToken: "test-token",
             scopes: ["user:profile"],
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -505,14 +506,14 @@ describe("usage", () => {
         },
       };
 
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("claude")) {
           return JSON.stringify({
             accessToken: "test-token",
             scopes: ["user:profile"],
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -593,14 +594,14 @@ describe("usage", () => {
       const noopSleep = vi.fn().mockResolvedValue(undefined);
       _setSleepFn(noopSleep);
 
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("claude")) {
           return JSON.stringify({
             accessToken: "test-token",
             scopes: ["user:profile"],
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -647,14 +648,14 @@ describe("usage", () => {
       const noopSleep = vi.fn().mockResolvedValue(undefined);
       _setSleepFn(noopSleep);
 
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("claude")) {
           return JSON.stringify({
             accessToken: "test-token",
             scopes: ["user:profile"],
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -698,14 +699,14 @@ describe("usage", () => {
       const noopSleep = vi.fn().mockResolvedValue(undefined);
       _setSleepFn(noopSleep);
 
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("claude")) {
           return JSON.stringify({
             accessToken: "test-token",
             scopes: ["user:profile"],
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -970,14 +971,14 @@ describe("usage", () => {
       const noopSleep = vi.fn().mockResolvedValue(undefined);
       _setSleepFn(noopSleep);
 
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("claude")) {
           return JSON.stringify({
             accessToken: "expired-token",
             scopes: ["user:profile"],
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -1040,14 +1041,14 @@ describe("usage", () => {
       const noopSleep = vi.fn().mockResolvedValue(undefined);
       _setSleepFn(noopSleep);
 
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("claude")) {
           return JSON.stringify({
             accessToken: "forbidden-token",
             scopes: ["user:profile"],
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -1534,8 +1535,8 @@ describe("usage", () => {
 
   describe("Codex provider", () => {
     it("detects no auth when auth.json doesn't exist", async () => {
-      mockReadFileSync.mockImplementation(() => {
-        throw new Error("File not found");
+      mockReadFile.mockImplementation(async () => {
+        return Promise.reject(new Error("File not found"));
       });
 
       const providers = await fetchAllProviderUsage();
@@ -1564,7 +1565,7 @@ describe("usage", () => {
         },
       };
 
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("codex")) {
           return JSON.stringify({
             tokens: {
@@ -1573,7 +1574,7 @@ describe("usage", () => {
             },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
 
       const mockReq = {
@@ -1625,7 +1626,7 @@ describe("usage", () => {
         },
       };
 
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("codex")) {
           return JSON.stringify({
             tokens: {
@@ -1633,7 +1634,7 @@ describe("usage", () => {
             },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
 
       const mockReq = { on: vi.fn(), write: vi.fn(), end: vi.fn() };
@@ -1669,7 +1670,7 @@ describe("usage", () => {
         },
       };
 
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("codex")) {
           return JSON.stringify({
             tokens: {
@@ -1677,7 +1678,7 @@ describe("usage", () => {
             },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
 
       const mockReq = { on: vi.fn(), write: vi.fn(), end: vi.fn() };
@@ -1709,8 +1710,8 @@ describe("usage", () => {
 
   describe("Gemini provider", () => {
     it("detects no auth when oauth_creds.json doesn't exist", async () => {
-      mockReadFileSync.mockImplementation(() => {
-        throw new Error("File not found");
+      mockReadFile.mockImplementation(async () => {
+        return Promise.reject(new Error("File not found"));
       });
 
       const providers = await fetchAllProviderUsage();
@@ -1737,7 +1738,7 @@ describe("usage", () => {
         ],
       };
 
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("gemini")) {
           if (path.includes("oauth_creds")) {
             return JSON.stringify({
@@ -1746,9 +1747,9 @@ describe("usage", () => {
             });
           }
           // settings.json doesn't exist (oauth-personal is default)
-          throw new Error("File not found");
+          return Promise.reject(new Error("File not found"));
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
 
       const mockReq = {
@@ -1799,7 +1800,7 @@ describe("usage", () => {
         ],
       };
 
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("gemini")) {
           if (path.includes("oauth_creds")) {
             return JSON.stringify({
@@ -1807,9 +1808,9 @@ describe("usage", () => {
               id_token: "header.eyJlbWFpbCI6InRlc3RAZXhhbXBsZS5jb20ifQ.signature",
             });
           }
-          throw new Error("File not found");
+          return Promise.reject(new Error("File not found"));
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
 
       const mockReq = { on: vi.fn(), write: vi.fn(), end: vi.fn() };
@@ -1835,7 +1836,7 @@ describe("usage", () => {
     });
 
     it("handles unsupported auth type (api-key)", async () => {
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("gemini")) {
           if (path.includes("oauth_creds")) {
             return JSON.stringify({
@@ -1852,7 +1853,7 @@ describe("usage", () => {
             });
           }
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
 
       const providers = await fetchAllProviderUsage();
@@ -1865,8 +1866,8 @@ describe("usage", () => {
 
   describe("Minimax provider", () => {
     it("detects no auth when pi auth.json doesn't exist", async () => {
-      mockReadFileSync.mockImplementation(() => {
-        throw new Error("File not found");
+      mockReadFile.mockImplementation(async () => {
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -1881,13 +1882,13 @@ describe("usage", () => {
     });
 
     it("detects no auth when minimax entry has no key", async () => {
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({
             minimax: { type: "api_key" /* missing key */ },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -1901,11 +1902,11 @@ describe("usage", () => {
     });
 
     it("detects no auth when minimax entry is missing entirely", async () => {
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({ /* no minimax key */ });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -1942,13 +1943,13 @@ describe("usage", () => {
         ],
       };
 
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({
             minimax: { type: "api_key", key: "test-api-key" },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2014,13 +2015,13 @@ describe("usage", () => {
         ],
       };
 
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({
             minimax: { type: "api_key", key: "test-api-key" },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2063,8 +2064,8 @@ describe("usage", () => {
         ],
       };
 
-      mockReadFileSync.mockImplementation(() => {
-        throw new Error("File not found");
+      mockReadFile.mockImplementation(async () => {
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2099,13 +2100,13 @@ describe("usage", () => {
     });
 
     it("handles 401 auth error", async () => {
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({
             minimax: { type: "api_key", key: "expired-key" },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2133,13 +2134,13 @@ describe("usage", () => {
     });
 
     it("handles 403 auth error", async () => {
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({
             minimax: { type: "api_key", key: "forbidden-key" },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2181,11 +2182,11 @@ describe("usage", () => {
         ],
       };
 
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({ minimax: { type: "api_key", key: "test-key" } });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2220,8 +2221,8 @@ describe("usage", () => {
 
   describe("Zai provider", () => {
     it("detects no auth when pi auth.json doesn't exist", async () => {
-      mockReadFileSync.mockImplementation(() => {
-        throw new Error("File not found");
+      mockReadFile.mockImplementation(async () => {
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2236,13 +2237,13 @@ describe("usage", () => {
     });
 
     it("detects no auth when zai entry has no key", async () => {
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({
             zai: { type: "api_key" /* missing key */ },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2284,13 +2285,13 @@ describe("usage", () => {
         success: true,
       };
 
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({
             zai: { type: "api_key", key: "test-api-key" },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2346,8 +2347,8 @@ describe("usage", () => {
         success: true,
       };
 
-      mockReadFileSync.mockImplementation(() => {
-        throw new Error("File not found");
+      mockReadFile.mockImplementation(async () => {
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2397,13 +2398,13 @@ describe("usage", () => {
         success: true,
       };
 
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".fusion/agent/auth.json")) {
           return JSON.stringify({
             zai: { type: "api_key", key: "fusion-zai-key" },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2446,13 +2447,13 @@ describe("usage", () => {
         success: true,
       };
 
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({
             zai: { type: "api_key", key: "test-api-key" },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2488,13 +2489,13 @@ describe("usage", () => {
         success: false,
       };
 
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({
             zai: { type: "api_key", key: "test-api-key" },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2522,13 +2523,13 @@ describe("usage", () => {
     });
 
     it("handles 401 auth error", async () => {
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({
             zai: { type: "api_key", key: "expired-key" },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2556,13 +2557,13 @@ describe("usage", () => {
     });
 
     it("handles 403 auth error", async () => {
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({
             zai: { type: "api_key", key: "forbidden-key" },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2607,11 +2608,11 @@ describe("usage", () => {
         success: true,
       };
 
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({ zai: { type: "api_key", key: "test-api-key" } });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2665,11 +2666,11 @@ describe("usage", () => {
         success: true,
       };
 
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({ zai: { type: "api_key", key: "test-api-key" } });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2762,14 +2763,14 @@ describe("usage", () => {
 
   describe("error handling", () => {
     it("handles Claude API errors gracefully", async () => {
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes("claude")) {
           return JSON.stringify({
             accessToken: "test-token",
             scopes: ["user:profile"],
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2797,14 +2798,14 @@ describe("usage", () => {
     });
 
     it("handles Claude network error", async () => {
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes("claude")) {
           return JSON.stringify({
             accessToken: "test-token",
             scopes: ["user:profile"],
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2834,7 +2835,7 @@ describe("usage", () => {
 
   describe("formatDuration helper", () => {
     it("formats duration correctly via resetText", async () => {
-      mockReadFileSync.mockImplementation((path: string) => {
+      mockReadFile.mockImplementation((path: string) => {
         if (path.includes("codex")) {
           return JSON.stringify({
             tokens: {
@@ -2842,7 +2843,7 @@ describe("usage", () => {
             },
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
 
       const mockResponse = {
@@ -2902,11 +2903,11 @@ describe("usage", () => {
         ],
       };
 
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({ minimax: { type: "api_key", key: "test-key" } });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -2953,11 +2954,11 @@ describe("usage", () => {
         ],
       };
 
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes(".pi/agent/auth.json")) {
           return JSON.stringify({ minimax: { type: "api_key", key: "test-key" } });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -3245,14 +3246,14 @@ describe("usage", () => {
 
   describe("Claude API error diagnostics", () => {
     it("includes response body snippet in HTTP 500 error", async () => {
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes("claude")) {
           return JSON.stringify({
             accessToken: "test-token",
             scopes: ["user:profile"],
           });
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
       mockExecFileSync.mockImplementation(() => {
         throw new Error("Keychain item not found");
@@ -3357,11 +3358,11 @@ describe("usage", () => {
     }) {
       const { credFileContent = null, keychainContent = null } = options;
 
-      mockReadFileSync.mockImplementation((filePath: string) => {
+      mockReadFile.mockImplementation((filePath: string) => {
         if (filePath.includes("claude") && credFileContent !== null) {
           return JSON.stringify(credFileContent);
         }
-        throw new Error("File not found");
+        return Promise.reject(new Error("File not found"));
       });
 
       mockExecFileSync.mockImplementation((cmd: string, _args: string[]) => {

packages/dashboard/src/usage.ts

@@ -1,5 +1,5 @@
-import * as fs from "node:fs";
 import * as path from "node:path";
+import { readFile } from "node:fs/promises";
 import * as https from "node:https";
 import * as child_process from "node:child_process";
 
@@ -241,9 +241,9 @@ function getAuthFileCandidates(): string[] {
   ];
 }
 
-function readAuthKeyFromFile(authPath: string, provider: string): string | null {
+async function readAuthKeyFromFile(authPath: string, provider: string): Promise<string | null> {
   try {
-    const auth = JSON.parse(fs.readFileSync(authPath, "utf-8"));
+    const auth = JSON.parse(await readFile(authPath, "utf-8"));
     const entry = auth?.[provider];
     if (entry && (entry.type === "api_key" || entry.type === "key") && entry.key) {
       return entry.key;
@@ -274,7 +274,7 @@ async function readConfiguredApiKey(provider: string, authStorage?: AuthStorageL
   } catch {}
 
   for (const authPath of getAuthFileCandidates()) {
-    const apiKey = readAuthKeyFromFile(authPath, provider);
+    const apiKey = await readAuthKeyFromFile(authPath, provider);
     if (apiKey) return apiKey;
   }
 
@@ -810,7 +810,7 @@ async function fetchClaudeUsage(): Promise<ProviderUsage> {
   let creds: any = null;
   for (const p of credPaths) {
     try {
-      creds = JSON.parse(fs.readFileSync(p, "utf-8"));
+      creds = JSON.parse(await readFile(p, "utf-8"));
       break;
     } catch {}
   }
@@ -1023,7 +1023,7 @@ async function fetchCodexUsage(): Promise<ProviderUsage> {
 
   let auth: any = null;
   try {
-    auth = JSON.parse(fs.readFileSync(authPath, "utf-8"));
+    auth = JSON.parse(await readFile(authPath, "utf-8"));
   } catch {
     usage.error = "No Codex credentials — run 'codex' to login";
     return usage;
@@ -1134,7 +1134,7 @@ async function fetchGeminiUsage(): Promise<ProviderUsage> {
   const oauthPath = path.join(process.env.HOME || "~", ".gemini", "oauth_creds.json");
   let oauthCreds: any = null;
   try {
-    oauthCreds = JSON.parse(fs.readFileSync(oauthPath, "utf-8"));
+    oauthCreds = JSON.parse(await readFile(oauthPath, "utf-8"));
   } catch {
     usage.error = "No Gemini credentials — run 'gemini' to login";
     return usage;
@@ -1154,7 +1154,7 @@ async function fetchGeminiUsage(): Promise<ProviderUsage> {
   // Check auth type from settings
   const settingsPath = path.join(process.env.HOME || "~", ".gemini", "settings.json");
   try {
-    const settings = JSON.parse(fs.readFileSync(settingsPath, "utf-8"));
+    const settings = JSON.parse(await readFile(settingsPath, "utf-8"));
     const authType = settings?.security?.auth?.selectedType;
     if (authType === "api-key" || authType === "vertex-ai") {
       usage.status = "error";