Merge pull request #2039 from modelcontextprotocol/v2/chore/1959-no-floating-promises

chore(lint): enable @typescript-eslint/no-floating-promises in all five ESLint scopes

clients/web/eslint.config.js

@@ -31,5 +31,32 @@ export default defineConfig([
       "react-refresh/only-export-components": "off",
     },
   },
+  {
+    // Type-aware pass for `no-floating-promises` (#1959). The rule needs type
+    // information, which `tseslint.configs.recommended` does not provide, and
+    // the parser needs a project that literally contains the linted file — so
+    // all four leaf projects are listed (`tsconfig.json` itself is a
+    // solution file with `files: []`, so it contains nothing).
+    //
+    // `.d.ts` is excluded: `vitest.shims.d.ts` is pulled in through a `types`
+    // reference rather than an `include`, so no project owns it, and a
+    // declaration file cannot float a promise anyway.
+    files: ["**/*.{ts,tsx}"],
+    ignores: ["**/*.d.ts"],
+    languageOptions: {
+      parserOptions: {
+        project: [
+          "./tsconfig.app.json",
+          "./tsconfig.node.json",
+          "./tsconfig.storybook.json",
+          "./tsconfig.test.json",
+        ],
+        tsconfigRootDir: import.meta.dirname,
+      },
+    },
+    rules: {
+      "@typescript-eslint/no-floating-promises": "error",
+    },
+  },
   ...storybook.configs["flat/recommended"],
 ]);

clients/web/server/server.ts

@@ -9,7 +9,6 @@ import { readFileSync } from "node:fs";
 import { join, dirname } from "node:path";
 import { fileURLToPath } from "node:url";
 import { randomBytes } from "node:crypto";
-import open from "open";
 import { serve } from "@hono/node-server";
 import { serveStatic } from "@hono/node-server/serve-static";
 import { Hono } from "hono";
@@ -22,6 +21,7 @@ import type { WebServerConfig } from "./web-server-config.js";
 import {
   webServerConfigToInitialPayload,
   printServerBanner,
+  openBrowser,
 } from "./web-server-config.js";
 import type { WebServerHandle } from "./types.js";
 
@@ -125,7 +125,9 @@ export async function startHonoServer(
         sandboxUrl ?? undefined,
       );
       if (config.autoOpen) {
-        open(url);
+        // Never a bare `open(url)`: this callback is synchronous, so a
+        // rejection would escape it. See openBrowser.
+        openBrowser(url);
       }
     },
   );

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

@@ -9,7 +9,6 @@
 
 import type { IncomingMessage, ServerResponse } from "node:http";
 import type { Plugin } from "vite";
-import open from "open";
 // Direct leaf import — the `core/mcp/remote/node/index.ts` barrel re-exports
 // from `../constants.js`, which would otherwise drag the broader
 // `core/mcp/remote/index.ts` barrel (including `createRemoteLogger`, with its
@@ -22,6 +21,7 @@ import type { WebServerConfig } from "./web-server-config.js";
 import {
   webServerConfigToInitialPayload,
   printServerBanner,
+  openBrowser,
 } from "./web-server-config.js";
 
 export function honoMiddlewarePlugin(config: WebServerConfig): Plugin {
@@ -114,7 +114,9 @@ export function honoMiddlewarePlugin(config: WebServerConfig): Plugin {
         );
 
         if (config.autoOpen) {
-          open(url);
+          // Never a bare `open(url)`: `logBanner` is synchronous, so a
+          // rejection would escape it. See openBrowser.
+          openBrowser(url);
         }
       };
 

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

@@ -2,6 +2,7 @@
  * Config object for the web server (dev and prod). Passed in-process; no env handoff.
  */
 
+import open from "open";
 import pino from "pino";
 import type { Logger } from "pino";
 import type { MCPConfig, MCPServerConfig } from "../../../core/mcp/types.ts";
@@ -203,6 +204,24 @@ export function printServerBanner(
   return url;
 }
 
+/**
+ * Launch the user's browser at `url`, reporting a failure rather than throwing.
+ *
+ * Both callers — the prod Hono server's `serve()` listen callback and the dev
+ * plugin's `logBanner` — are synchronous, so a rejection has nowhere to go and
+ * escapes as an unhandled rejection (#1959). On a headless or otherwise
+ * browser-less host that rejection is the ordinary outcome, not an edge case,
+ * and by the time it happens the server is already listening and
+ * `printServerBanner` has printed a perfectly usable URL. So warn and carry
+ * on. Shared between the two servers deliberately: two copies of a one-line
+ * `.catch` is two chances for one of them to drift back to a bare `open(url)`.
+ */
+export function openBrowser(url: string): void {
+  open(url).catch((err: unknown) => {
+    console.warn("Could not open a browser automatically:", err);
+  });
+}
+
 export interface BuildWebServerConfigOptions {
   initialMcpConfig?: MCPServerConfig | null;
   /** Catalog/session file the backend should serve; see {@link WebServerConfig.mcpConfigPath}. */

clients/web/src/components/elements/CategoryBadge/CategoryBadge.stories.tsx

@@ -14,7 +14,7 @@ export const Transport: Story = {
   args: { category: "transport" },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByText("transport")).toBeInTheDocument();
+    await expect(canvas.getByText("transport")).toBeInTheDocument();
   },
 };
 
@@ -22,6 +22,6 @@ export const Auth: Story = {
   args: { category: "auth" },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByText("auth")).toBeInTheDocument();
+    await expect(canvas.getByText("auth")).toBeInTheDocument();
   },
 };

clients/web/src/components/elements/EmbeddableScrollArea/EmbeddableScrollArea.stories.tsx

@@ -24,7 +24,7 @@ export const FullSize: Story = {
   ),
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByText("Row 1")).toBeInTheDocument();
+    await expect(canvas.getByText("Row 1")).toBeInTheDocument();
   },
 };
 
@@ -38,6 +38,6 @@ export const Embedded: Story = {
   ),
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByText("Row 1")).toBeInTheDocument();
+    await expect(canvas.getByText("Row 1")).toBeInTheDocument();
   },
 };

clients/web/src/components/elements/ExpandToggle/ExpandToggle.stories.tsx

@@ -15,7 +15,9 @@ export const Collapsed: Story = {
   args: { expanded: false },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByRole("button", { name: "Expand" })).toBeInTheDocument();
+    await expect(
+      canvas.getByRole("button", { name: "Expand" }),
+    ).toBeInTheDocument();
   },
 };
 
@@ -23,7 +25,7 @@ export const Expanded: Story = {
   args: { expanded: true },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(
+    await expect(
       canvas.getByRole("button", { name: "Collapse" }),
     ).toBeInTheDocument();
   },

clients/web/src/components/elements/McpErrorBadge/McpErrorBadge.stories.tsx

@@ -14,7 +14,7 @@ export const HeaderMismatch: Story = {
   args: { code: -32020, name: "HeaderMismatch" },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByText("-32020 HeaderMismatch")).toBeInTheDocument();
+    await expect(canvas.getByText("-32020 HeaderMismatch")).toBeInTheDocument();
   },
 };
 
@@ -22,7 +22,7 @@ export const MissingCapability: Story = {
   args: { code: -32021, name: "MissingRequiredClientCapability" },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(
+    await expect(
       canvas.getByText("-32021 MissingRequiredClientCapability"),
     ).toBeInTheDocument();
   },
@@ -32,7 +32,7 @@ export const UnsupportedVersion: Story = {
   args: { code: -32022, name: "UnsupportedProtocolVersion" },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(
+    await expect(
       canvas.getByText("-32022 UnsupportedProtocolVersion"),
     ).toBeInTheDocument();
   },
@@ -47,6 +47,6 @@ export const MethodNotFound: Story = {
   },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByText("-32601 MethodNotFound")).toBeInTheDocument();
+    await expect(canvas.getByText("-32601 MethodNotFound")).toBeInTheDocument();
   },
 };

clients/web/src/components/elements/MessageDirectionBadge/MessageDirectionBadge.stories.tsx

@@ -14,7 +14,7 @@ export const Outgoing: Story = {
   args: { direction: "outgoing" },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByText("client → server")).toBeInTheDocument();
+    await expect(canvas.getByText("client → server")).toBeInTheDocument();
   },
 };
 
@@ -22,6 +22,6 @@ export const Incoming: Story = {
   args: { direction: "incoming" },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByText("server → client")).toBeInTheDocument();
+    await expect(canvas.getByText("server → client")).toBeInTheDocument();
   },
 };

clients/web/src/components/elements/MethodBadge/MethodBadge.stories.tsx

@@ -14,7 +14,7 @@ export const ToolsList: Story = {
   args: { method: "tools/list" },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByText("tools/list")).toBeInTheDocument();
+    await expect(canvas.getByText("tools/list")).toBeInTheDocument();
   },
 };
 
@@ -22,6 +22,6 @@ export const TasksList: Story = {
   args: { method: "tasks/list" },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByText("tasks/list")).toBeInTheDocument();
+    await expect(canvas.getByText("tasks/list")).toBeInTheDocument();
   },
 };

clients/web/src/components/elements/MonitoringToggle/MonitoringToggle.stories.tsx

@@ -15,7 +15,7 @@ export const Closed: Story = {
   args: { open: false },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(
+    await expect(
       canvas.getByRole("button", { name: "Open monitoring sidebar" }),
     ).toBeInTheDocument();
   },
@@ -25,7 +25,7 @@ export const Open: Story = {
   args: { open: true },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(
+    await expect(
       canvas.getByRole("button", { name: "Close monitoring sidebar" }),
     ).toBeInTheDocument();
   },

clients/web/src/components/elements/PinToggle/PinToggle.stories.tsx

@@ -15,7 +15,9 @@ export const Unpinned: Story = {
   args: { pinned: false },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByRole("button", { name: "Pin" })).toBeInTheDocument();
+    await expect(
+      canvas.getByRole("button", { name: "Pin" }),
+    ).toBeInTheDocument();
   },
 };
 
@@ -23,6 +25,8 @@ export const Pinned: Story = {
   args: { pinned: true },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByRole("button", { name: "Unpin" })).toBeInTheDocument();
+    await expect(
+      canvas.getByRole("button", { name: "Unpin" }),
+    ).toBeInTheDocument();
   },
 };

clients/web/src/components/elements/ReplayButton/ReplayButton.stories.tsx

@@ -14,6 +14,8 @@ type Story = StoryObj<typeof ReplayButton>;
 export const Default: Story = {
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByRole("button", { name: "Replay" })).toBeInTheDocument();
+    await expect(
+      canvas.getByRole("button", { name: "Replay" }),
+    ).toBeInTheDocument();
   },
 };

clients/web/src/components/elements/ResizeHandle/ResizeHandle.stories.tsx

@@ -44,7 +44,7 @@ export const Default: Story = {
   render: () => <ResizeDemo />,
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(
+    await expect(
       canvas.getByRole("separator", { name: "Resize demo panel" }),
     ).toBeInTheDocument();
   },

clients/web/src/components/elements/ScreenStage/ScreenStage.stories.tsx

@@ -48,7 +48,7 @@ export const FillsHostWidth: Story = {
     // sharper discriminator: a row flex leaves the layer full-width while
     // collapsing the child to the single "x").
     const layer = child.parentElement as HTMLElement;
-    expect(child.getBoundingClientRect().width).toBeCloseTo(
+    await expect(child.getBoundingClientRect().width).toBeCloseTo(
       layer.getBoundingClientRect().width,
       0,
     );
@@ -77,11 +77,11 @@ export const FillVariant: Story = {
     // Width still stretches onto the child (relative to the layer, as above);
     // the `fill` height comes from `bottom: 0` making the layer span the host.
     const layer = child.parentElement as HTMLElement;
-    expect(child.getBoundingClientRect().width).toBeCloseTo(
+    await expect(child.getBoundingClientRect().width).toBeCloseTo(
       layer.getBoundingClientRect().width,
       0,
     );
-    expect(layer.getBoundingClientRect().height).toBeGreaterThan(160 - 4);
+    await expect(layer.getBoundingClientRect().height).toBeGreaterThan(160 - 4);
   },
 };
 
@@ -97,6 +97,6 @@ export const Inactive: Story = {
   ),
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.queryByTestId("stage-child")).not.toBeInTheDocument();
+    await expect(canvas.queryByTestId("stage-child")).not.toBeInTheDocument();
   },
 };

clients/web/src/components/groups/ConnectionInfoContent/ConnectionInfoContent.stories.tsx

@@ -114,8 +114,10 @@ export const ServerInfoNotReported: Story = {
   },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.queryByText("my-catalog-name")).not.toBeInTheDocument();
-    expect(canvas.getAllByText(SERVER_INFO_NOT_REPORTED_LABEL)).toHaveLength(2);
+    await expect(canvas.queryByText("my-catalog-name")).not.toBeInTheDocument();
+    await expect(
+      canvas.getAllByText(SERVER_INFO_NOT_REPORTED_LABEL),
+    ).toHaveLength(2);
   },
 };
 
@@ -195,11 +197,11 @@ export const WithOAuthIdToken: Story = {
   },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByText("ID Token")).toBeInTheDocument();
+    await expect(canvas.getByText("ID Token")).toBeInTheDocument();
     // Only the ID token is a JWT here, so exactly one decode toggle is offered.
     await userEvent.click(
       canvas.getByRole("button", { name: "Decode JWT for ID Token" }),
     );
-    expect(canvas.getByText(/"sub": "user-42"/)).toBeInTheDocument();
+    await expect(canvas.getByText(/"sub": "user-42"/)).toBeInTheDocument();
   },
 };

clients/web/src/components/groups/LogStreamPanel/LogStreamPanel.stories.tsx

@@ -77,6 +77,6 @@ export const WithEntries: Story = {
   },
   // List scrollbar reserves a gutter and stays hidden when idle (#1474).
   play: async ({ canvasElement }) => {
-    expectScrollbarGutterIdleHidden(canvasElement);
+    await expectScrollbarGutterIdleHidden(canvasElement);
   },
 };

clients/web/src/components/groups/MessageDirectionFilter/MessageDirectionFilter.stories.tsx

@@ -31,10 +31,10 @@ export const AllVisible: Story = {
   args: { visibleDirections: { client: true, server: true } },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(
+    await expect(
       canvas.getByRole("button", { name: "client → server" }),
     ).toBeInTheDocument();
-    expect(
+    await expect(
       canvas.getByRole("button", { name: "Deselect All" }),
     ).toBeInTheDocument();
   },

clients/web/src/components/groups/MonitoringControls/MonitoringControls.stories.tsx

@@ -20,7 +20,7 @@ type Story = StoryObj<typeof MonitoringControls>;
 export const AllTabs: Story = {
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByRole("radio", { name: "Logs" })).toBeChecked();
+    await expect(canvas.getByRole("radio", { name: "Logs" })).toBeChecked();
   },
 };
 
@@ -28,6 +28,6 @@ export const StdioServer: Story = {
   args: { tabs: ["Logs", "Protocol"], value: "Protocol" },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.queryByRole("radio", { name: "Network" })).toBeNull();
+    await expect(canvas.queryByRole("radio", { name: "Network" })).toBeNull();
   },
 };

clients/web/src/components/groups/MonitoringScreen/MonitoringScreen.stories.tsx

@@ -47,7 +47,7 @@ type Story = StoryObj<typeof MonitoringScreen>;
 export const Logs: Story = {
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByText("Log stream")).toBeInTheDocument();
+    await expect(canvas.getByText("Log stream")).toBeInTheDocument();
   },
 };
 
@@ -55,6 +55,6 @@ export const Protocol: Story = {
   args: { value: "Protocol" },
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
-    expect(canvas.getByText("Request history")).toBeInTheDocument();
+    await expect(canvas.getByText("Request history")).toBeInTheDocument();
   },
 };