Made logging consistent between all clients (using MCP_LOG_FILE), updated client readmes. Made logging initializaiton async so we have logging ready before app runs or does an early exit (this addresses the SonicBoom errors seen on early app termination). Reorganized shared logging code (which is node code) into core/logging/node. Fixed CLI error reporting through launcher (just error message now, no stack trace).

BobDickinson · BobDickinson · commit b318070b1639 · 2026-03-18T12:02:57.000-07:00
diff --git a/clients/cli/README.md b/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:
diff --git a/clients/cli/src/cli.ts b/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> {
diff --git a/clients/tui/README.md b/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:
diff --git a/clients/tui/src/logger.ts b/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;
+  }
+}
diff --git a/clients/tui/tui.tsx b/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
diff --git a/clients/web/README.md b/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                |
 
diff --git a/clients/web/src/components/AuthDebugger.tsx b/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/node";
 import type { AuthGuidedState } from "@modelcontextprotocol/inspector-core/auth/types.js";
 import type { WebEnvironmentResult } from "@/lib/adapters/environmentFactory";
 import { OAuthFlowProgress } from "./OAuthFlowProgress";
diff --git a/clients/web/src/components/OAuthCallback.tsx b/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/node";
 import useTheme from "@/lib/hooks/useTheme";
 import { useToast } from "@/lib/hooks/useToast";
 import {
diff --git a/clients/web/src/server.ts b/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));
diff --git a/clients/web/src/vite-hono-plugin.ts b/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);
         }
       };
diff --git a/clients/web/src/web-server-config.ts b/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 +168,14 @@ 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",
+      })
+    : silentLogger;
 
   return {
     port,
diff --git a/clients/web/src/web.ts b/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 +258,22 @@ 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",
+      })
+    : silentLogger;
+
   const webConfig = buildWebServerConfig(
     clientOptions,
     port,
     hostname,
     authToken,
     dangerouslyOmitAuth,
+    logger,
   );
   if (!clientOptions.isDev) {
     webConfig.staticRoot = join(__dirname, "..", "dist");
diff --git a/core/auth/index.ts b/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";
diff --git a/core/logging/index.ts b/core/logging/index.ts
diff --git a/core/logging/node/fileLogger.ts b/core/logging/node/fileLogger.ts
diff --git a/core/logging/node/index.ts b/core/logging/node/index.ts
diff --git a/core/logging/node/logger.ts b/core/logging/node/logger.ts
diff --git a/core/mcp/inspectorClient.ts b/core/mcp/inspectorClient.ts
diff --git a/core/package.json b/core/package.json
