Logging updates (including reported SonicBoom error)

clients/cli/README.md

@@ -98,6 +98,12 @@ Options that specify the MCP server (config file, ad-hoc command/URL, env vars,
 | `--metadata <key=value>`      | General metadata (key=value); applied to all methods.                                     |
 | `--tool-metadata <key=value>` | Tool-specific metadata for `tools/call`.                                                  |
 
+### Logging (env)
+
+| Env var        | Description                                                     |
+| -------------- | --------------------------------------------------------------- |
+| `MCP_LOG_FILE` | If set, CLI and InspectorClient logs are appended to this file. |
+
 ## Why use the CLI?
 
 While the Web Client provides a rich visual interface, the CLI is designed for:

clients/cli/src/cli.ts

@@ -18,6 +18,10 @@ import {
   parseKeyValuePair as parseEnvPair,
   parseHeaderPair,
 } from "@modelcontextprotocol/inspector-core/mcp/node/index.js";
+import {
+  createFileLogger,
+  silentLogger,
+} from "@modelcontextprotocol/inspector-core/logging/node";
 import type { JsonValue } from "@modelcontextprotocol/inspector-core/mcp/index.js";
 import {
   LoggingLevelSchema,
@@ -58,9 +62,21 @@ async function callMethod(
   const version = packageJson.version;
   const clientIdentity = { name, version };
 
+  const logger = process.env.MCP_LOG_FILE
+    ? await createFileLogger({
+        dest: process.env.MCP_LOG_FILE,
+        append: true,
+        mkdir: true,
+        level: "info",
+        name: "mcp-inspector-cli",
+      })
+    : silentLogger;
+  logger.info("CLI starting");
+
   const inspectorClient = new InspectorClient(serverConfig, {
     environment: {
       transport: createTransportNode,
+      logger,
     },
     clientIdentity,
     initialLoggingLevel: "debug",
@@ -413,8 +429,12 @@ function parseArgs(argv?: string[]): {
 }
 
 export async function runCli(argv?: string[]): Promise<void> {
-  const { serverConfig, methodArgs } = parseArgs(argv ?? process.argv);
-  await callMethod(serverConfig, methodArgs);
+  try {
+    const { serverConfig, methodArgs } = parseArgs(argv ?? process.argv);
+    await callMethod(serverConfig, methodArgs);
+  } catch (error) {
+    handleError(error);
+  }
 }
 
 export async function main(): Promise<void> {

clients/tui/README.md

@@ -39,6 +39,12 @@ When connecting to SSE or Streamable HTTP servers that use OAuth, you can pass:
 | `--client-metadata-url <url>` | OAuth Client ID Metadata Document URL (CIMD).                                        |
 | `--callback-url <url>`        | OAuth redirect/callback listener URL (default: `http://127.0.0.1:0/oauth/callback`). |
 
+### Logging (env)
+
+| Env var        | Description                                                     |
+| -------------- | --------------------------------------------------------------- |
+| `MCP_LOG_FILE` | If set, TUI and InspectorClient logs are appended to this file. |
+
 ## Features
 
 The TUI provides terminal-native tabs and panes for interacting with your MCP server:

clients/tui/src/logger.ts

@@ -1,23 +1,30 @@
-import path from "node:path";
-import pino from "pino";
+import type { Logger } from "pino";
+import {
+  silentLogger,
+  createFileLogger,
+} from "@modelcontextprotocol/inspector-core/logging/node";
 
-const logDir =
-  process.env.MCP_INSPECTOR_LOG_DIR ??
-  path.join(
-    process.env.HOME || process.env.USERPROFILE || ".",
-    ".mcp-inspector",
-  );
-const logPath = path.join(logDir, "auth.log");
+/**
+ * TUI logger (InspectorClient events, auth, etc.).
+ * File logger when MCP_LOG_FILE is set, else silentLogger.
+ */
+export let tuiLogger: Logger = silentLogger;
 
 /**
- * TUI file logger for auth and InspectorClient events.
- * Writes to ~/.mcp-inspector/auth.log so TUI console output is not corrupted.
- * The app controls logger creation and configuration.
+ * If MCP_LOG_FILE is set, creates a file logger (awaits destination ready);
+ * otherwise uses silentLogger. Call at the start of runTui() before any work
+ * that might call process.exit().
  */
-export const tuiLogger = pino(
-  {
-    name: "mcp-inspector-tui",
-    level: process.env.LOG_LEVEL ?? "info",
-  },
-  pino.destination({ dest: logPath, append: true, mkdir: true }),
-);
+export async function initTuiLogger(): Promise<void> {
+  if (process.env.MCP_LOG_FILE) {
+    tuiLogger = await createFileLogger({
+      dest: process.env.MCP_LOG_FILE,
+      append: true,
+      mkdir: true,
+      level: "info",
+      name: "mcp-inspector-tui",
+    });
+  } else {
+    tuiLogger = silentLogger;
+  }
+}

clients/tui/tui.tsx

@@ -9,9 +9,13 @@ import {
   parseKeyValuePair,
   parseHeaderPair,
 } from "@modelcontextprotocol/inspector-core/mcp/node/index.js";
+import { initTuiLogger, tuiLogger } from "./src/logger.js";
 import App from "./src/App.js";
 
 export async function runTui(args?: string[]): Promise<void> {
+  await initTuiLogger();
+  tuiLogger.info("TUI starting");
+
   const program = new Command();
 
   program

clients/web/README.md

@@ -72,7 +72,7 @@ All of these are set via **environment variables**; the web app has no command-l
 | **Sandbox port** (MCP Apps)        | Env: `MCP_SANDBOX_PORT`; if unset, `SERVER_PORT` (legacy). Use `0` or leave unset for an automatic port.                           | automatic          |
 | **Storage directory** (e.g. OAuth) | Env: `MCP_STORAGE_DIR`                                                                                                             | (unset)            |
 | **Allowed origins** (CORS)         | Env: `ALLOWED_ORIGINS` (comma-separated)                                                                                           | client origin only |
-| **Log file**                       | Env: `MCP_LOG_FILE` — if set, server logs are appended to this file.                                                               | (unset)            |
+| **Log file**                       | Env: `MCP_LOG_FILE` — if set, server and InspectorClient logs are appended to this file.                                           | (unset)            |
 | **Open browser on start**          | Env: `MCP_AUTO_OPEN_ENABLED` — set to `false` to disable.                                                                          | `true`             |
 | **Development mode**               | CLI only: `--dev` (Vite with HMR). No env var.                                                                                     | off                |
 

clients/web/src/components/AuthDebugger.tsx

@@ -2,7 +2,7 @@ import { useCallback, useEffect, useState } from "react";
 import { Button } from "@/components/ui/button";
 import { AlertCircle } from "lucide-react";
 import type { InspectorClient } from "@modelcontextprotocol/inspector-core/mcp/index.js";
-import { silentLogger } from "@modelcontextprotocol/inspector-core/logging";
+import { silentLogger } from "@modelcontextprotocol/inspector-core/logging/browser";
 import type { AuthGuidedState } from "@modelcontextprotocol/inspector-core/auth/types.js";
 import type { WebEnvironmentResult } from "@/lib/adapters/environmentFactory";
 import { OAuthFlowProgress } from "./OAuthFlowProgress";

clients/web/src/components/OAuthCallback.tsx

@@ -2,7 +2,7 @@ import { useCallback, useEffect, useRef, useState } from "react";
 import type { InspectorClient } from "@modelcontextprotocol/inspector-core/mcp/index.js";
 import type { WebEnvironmentResult } from "@/lib/adapters/environmentFactory";
 import { parseOAuthState } from "@modelcontextprotocol/inspector-core/auth/index.js";
-import { silentLogger } from "@modelcontextprotocol/inspector-core/logging";
+import { silentLogger } from "@modelcontextprotocol/inspector-core/logging/browser";
 import useTheme from "@/lib/hooks/useTheme";
 import { useToast } from "@/lib/hooks/useToast";
 import {

clients/web/src/server.ts

@@ -34,6 +34,7 @@ export interface WebServerHandle {
 export async function startHonoServer(
   config: WebServerConfig,
 ): Promise<WebServerHandle> {
+  config.logger.info("Web server starting");
   const sandboxController = createSandboxController({
     port: config.sandboxPort,
     host: config.sandboxHost,
@@ -131,7 +132,7 @@ export async function startHonoServer(
 
 /** Run when this file is executed as the main module (e.g. node dist/server.js). */
 async function runStandalone(): Promise<void> {
-  const config = buildWebServerConfigFromEnv();
+  const config = await buildWebServerConfigFromEnv();
   const handle = await startHonoServer(config);
   const shutdown = () => {
     void handle.close().then(() => process.exit(0));

clients/web/src/vite-hono-plugin.ts

@@ -15,15 +15,20 @@ import {
 } from "./web-server-config.js";
 
 /**
- * Plugin factory. Caller must pass a WebServerConfig (runner builds it from argv; vite.config builds it from env via buildWebServerConfigFromEnv).
+ * Plugin factory. Caller must pass a WebServerConfig or Promise<WebServerConfig>
+ * (runner builds from argv; vite.config passes buildWebServerConfigFromEnv() which is async).
  */
-export function honoMiddlewarePlugin(config: WebServerConfig): Plugin {
+export function honoMiddlewarePlugin(
+  config: WebServerConfig | Promise<WebServerConfig>,
+): Plugin {
   return {
     name: "hono-api-middleware",
     async configureServer(server) {
+      const resolvedConfig = await Promise.resolve(config);
+      resolvedConfig.logger.info("Web server starting (dev)");
       const sandboxController = createSandboxController({
-        port: config.sandboxPort,
-        host: config.sandboxHost,
+        port: resolvedConfig.sandboxPort,
+        host: resolvedConfig.sandboxHost,
       });
       await sandboxController.start();
 
@@ -40,13 +45,15 @@ export function honoMiddlewarePlugin(config: WebServerConfig): Plugin {
       };
 
       const { app: honoApp, authToken: resolvedToken } = createRemoteApp({
-        authToken: config.dangerouslyOmitAuth ? undefined : config.authToken,
-        dangerouslyOmitAuth: config.dangerouslyOmitAuth,
-        storageDir: config.storageDir,
-        allowedOrigins: config.allowedOrigins,
+        authToken: resolvedConfig.dangerouslyOmitAuth
+          ? undefined
+          : resolvedConfig.authToken,
+        dangerouslyOmitAuth: resolvedConfig.dangerouslyOmitAuth,
+        storageDir: resolvedConfig.storageDir,
+        allowedOrigins: resolvedConfig.allowedOrigins,
         sandboxUrl: sandboxController.getUrl() ?? undefined,
-        logger: config.logger,
-        initialConfig: webServerConfigToInitialPayload(config),
+        logger: resolvedConfig.logger,
+        initialConfig: webServerConfigToInitialPayload(resolvedConfig),
       });
 
       const sandboxUrl = sandboxController.getUrl();
@@ -56,16 +63,16 @@ export function honoMiddlewarePlugin(config: WebServerConfig): Plugin {
         const actualPort =
           typeof address === "object" && address !== null
             ? address.port
-            : config.port;
+            : resolvedConfig.port;
 
         const url = printServerBanner(
-          config,
+          resolvedConfig,
           actualPort,
           resolvedToken,
           sandboxUrl ?? undefined,
         );
 
-        if (config.autoOpen) {
+        if (resolvedConfig.autoOpen) {
           open(url);
         }
       };

clients/web/src/web-server-config.ts

@@ -2,9 +2,12 @@
  * Config object for the web server (dev and prod). Passed in-process; no env handoff.
  */
 
-import pino from "pino";
 import type { Logger } from "pino";
 import type { MCPServerConfig } from "@modelcontextprotocol/inspector-core/mcp/types.js";
+import {
+  createFileLogger,
+  silentLogger,
+} from "@modelcontextprotocol/inspector-core/logging/node";
 import {
   API_SERVER_ENV_VARS,
   LEGACY_AUTH_TOKEN_ENV,
@@ -24,7 +27,7 @@ export interface WebServerConfig {
   /** Sandbox port (0 = dynamic). */
   sandboxPort: number;
   sandboxHost: string;
-  logger: Logger | undefined;
+  logger: Logger;
   /** When true, open browser after server starts. */
   autoOpen: boolean;
   /** Root directory for static files (index.html, assets). When runner starts server in-process, pass path to dist/. */
@@ -148,8 +151,9 @@ export function printServerBanner(
 
 /**
  * Build WebServerConfig from process.env. Used when running server as standalone (e.g. node dist/server.js).
+ * When MCP_LOG_FILE is set, returns a Promise (file logger destination must be awaited).
  */
-export function buildWebServerConfigFromEnv(): WebServerConfig {
+export async function buildWebServerConfigFromEnv(): Promise<WebServerConfig> {
   const port = parseInt(process.env.CLIENT_PORT ?? "6274", 10);
   const hostname = process.env.HOST ?? "localhost";
   const baseUrl = `http://${hostname}:${port}`;
@@ -164,17 +168,15 @@ export function buildWebServerConfigFromEnv(): WebServerConfig {
 
   const sandboxPort = resolveSandboxPort();
 
-  let logger: Logger | undefined;
-  if (process.env.MCP_LOG_FILE) {
-    logger = pino(
-      { level: "info" },
-      pino.destination({
+  const logger = process.env.MCP_LOG_FILE
+    ? await createFileLogger({
         dest: process.env.MCP_LOG_FILE,
         append: true,
         mkdir: true,
-      }),
-    );
-  }
+        level: "info",
+        name: "mcp-inspector-web",
+      })
+    : silentLogger;
 
   return {
     port,

clients/web/src/web.ts

@@ -2,6 +2,7 @@ import { resolve, join, dirname } from "path";
 import { fileURLToPath } from "url";
 import { randomBytes } from "crypto";
 import { Command } from "commander";
+import type { Logger } from "pino";
 import type {
   MCPServerConfig,
   StreamableHttpServerConfig,
@@ -16,6 +17,10 @@ import {
   parseHeaderPair,
   type ServerConfigOptions,
 } from "@modelcontextprotocol/inspector-core/mcp/node/config.js";
+import {
+  createFileLogger,
+  silentLogger,
+} from "@modelcontextprotocol/inspector-core/logging/node";
 import { resolveSandboxPort } from "./sandbox-controller.js";
 import type { WebServerConfig } from "./web-server-config.js";
 import { startViteDevServer } from "./start-vite-dev-server.js";
@@ -93,6 +98,7 @@ function buildWebServerConfig(
   hostname: string,
   authToken: string,
   dangerouslyOmitAuth: boolean,
+  logger: Logger,
 ): WebServerConfig {
   const baseUrl = `http://${hostname}:${port}`;
   const initialMcpConfig: MCPServerConfig | null =
@@ -136,7 +142,7 @@ function buildWebServerConfig(
     ],
     sandboxPort: resolveSandboxPort(),
     sandboxHost: hostname,
-    logger: undefined,
+    logger,
     autoOpen: process.env.MCP_AUTO_OPEN_ENABLED !== "false",
   };
 }
@@ -252,12 +258,23 @@ export async function runWeb(argv: string[]): Promise<number> {
       (process.env[LEGACY_AUTH_TOKEN_ENV] as string | undefined) ??
       randomBytes(32).toString("hex"));
 
+  const logger = process.env.MCP_LOG_FILE
+    ? await createFileLogger({
+        dest: process.env.MCP_LOG_FILE,
+        append: true,
+        mkdir: true,
+        level: "info",
+        name: "mcp-inspector-web",
+      })
+    : silentLogger;
+
   const webConfig = buildWebServerConfig(
     clientOptions,
     port,
     hostname,
     authToken,
     dangerouslyOmitAuth,
+    logger,
   );
   if (!clientOptions.isDev) {
     webConfig.staticRoot = join(__dirname, "..", "dist");

core/auth/index.ts

@@ -40,8 +40,8 @@ export type { OAuthStateMode } from "./utils.js";
 // Discovery
 export { discoverScopes } from "./discovery.js";
 
-// Logging (re-exported from core/logging)
-export { silentLogger } from "../logging/index.js";
+// Logging (re-exported from core/logging/node)
+export { silentLogger } from "../logging/node/index.js";
 // State Machine
 export type { StateMachineContext, StateTransition } from "./state-machine.js";
 export { oauthTransitions, OAuthStateMachine } from "./state-machine.js";

core/logging/browser/logger.ts

@@ -0,0 +1,10 @@
+/**
+ * Silent logger for browser contexts. Satisfies pino.Logger; does not output anything.
+ * Use when no logger is passed (e.g. OAuth callback with no client). Web components
+ * that need a fallback import from logging/browser so they don't pull in Node logging.
+ */
+// @ts-expect-error - pino/browser.js exists but TypeScript doesn't have types for the .js extension
+import pino from "pino/browser.js";
+import type { Logger } from "pino";
+
+export const silentLogger: Logger = pino({ level: "silent" });