Address @claude review: format core/, typed output-validation error, document progress heuristic

- Run Prettier on the 60 core/ files this PR touched — the deterministic
  import rewrite had collapsed multi-line imports and left throws unwrapped;
  core/ is in no format gate so it slipped past CI. Now Prettier-clean.
- Default-path output-schema violation now throws
  ProtocolError(ProtocolErrorCode.InvalidParams, …) instead of a bare Error,
  matching the prior v1 contract (SDK threw a typed McpError with a code) so
  downstream `instanceof`/`.code` branching keeps working.
- Document the "assumes serial construction" invariant on pollTaskToolCall's
  progress-subscription revival (the `_progressHandlers` new-key heuristic).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

core/mcp/__tests__/fakeInspectorClient.ts

@@ -6,7 +6,17 @@
  */
 
 import { vi } from "vitest";
-import type { ClientCapabilities, Implementation, LoggingLevel, Prompt, Resource, ResourceTemplateType as ResourceTemplate, ServerCapabilities, Task, Tool } from "@modelcontextprotocol/client";
+import type {
+  ClientCapabilities,
+  Implementation,
+  LoggingLevel,
+  Prompt,
+  Resource,
+  ResourceTemplateType as ResourceTemplate,
+  ServerCapabilities,
+  Task,
+  Tool,
+} from "@modelcontextprotocol/client";
 import { InspectorClientEventTarget } from "../inspectorClientEventTarget.js";
 import type {
   AppRendererClient,

core/mcp/inspectorClient.ts

@@ -46,7 +46,38 @@ import {
   MessageTrackingTransport,
   type MessageTrackingCallbacks,
 } from "./messageTrackingTransport.js";
-import type { CallToolRequest, JSONRPCRequest, JSONRPCNotification, JSONRPCResultResponse, JSONRPCErrorResponse, ServerCapabilities, ClientCapabilities, Implementation, LoggingLevel, Tool, Resource, ResourceTemplateType as ResourceTemplate, Prompt, Root, CreateMessageRequest, CreateMessageResult, ElicitRequest, ElicitResult, ElicitRequestURLParams, CallToolResult, Task, Progress, ProgressToken, ListToolsRequest, ListResourcesRequest, ListResourceTemplatesRequest, ListPromptsRequest, ReadResourceRequest, GetPromptRequest, CompleteRequest } from "@modelcontextprotocol/client";
+import type {
+  CallToolRequest,
+  JSONRPCRequest,
+  JSONRPCNotification,
+  JSONRPCResultResponse,
+  JSONRPCErrorResponse,
+  ServerCapabilities,
+  ClientCapabilities,
+  Implementation,
+  LoggingLevel,
+  Tool,
+  Resource,
+  ResourceTemplateType as ResourceTemplate,
+  Prompt,
+  Root,
+  CreateMessageRequest,
+  CreateMessageResult,
+  ElicitRequest,
+  ElicitResult,
+  ElicitRequestURLParams,
+  CallToolResult,
+  Task,
+  Progress,
+  ProgressToken,
+  ListToolsRequest,
+  ListResourcesRequest,
+  ListResourceTemplatesRequest,
+  ListPromptsRequest,
+  ReadResourceRequest,
+  GetPromptRequest,
+  CompleteRequest,
+} from "@modelcontextprotocol/client";
 import type { Transport } from "@modelcontextprotocol/client";
 import type {
   RequestOptions,
@@ -633,9 +664,7 @@ export class InspectorClient extends InspectorClientEventTarget {
     internal._requestHandlers.set(method, (request, ctx) => {
       const task = (request as { params?: { task?: unknown } })?.params?.task;
       if (this.receiverTasks && task != null) {
-        return rawHandler(
-          request as CreateMessageRequest & ElicitRequest,
-        );
+        return rawHandler(request as CreateMessageRequest & ElicitRequest);
       }
       return validating(request, ctx);
     });
@@ -723,7 +752,10 @@ export class InspectorClient extends InspectorClientEventTarget {
   private async getReceiverTaskPayload(taskId: string): Promise<ClientResult> {
     const record = this.receiverTaskRecords.get(taskId);
     if (!record) {
-      throw new ProtocolError(ProtocolErrorCode.InvalidParams, `Unknown taskId: ${taskId}`);
+      throw new ProtocolError(
+        ProtocolErrorCode.InvalidParams,
+        `Unknown taskId: ${taskId}`,
+      );
     }
     return record.payloadPromise;
   }
@@ -731,7 +763,10 @@ export class InspectorClient extends InspectorClientEventTarget {
   private cancelReceiverTask(taskId: string): Task {
     const record = this.receiverTaskRecords.get(taskId);
     if (!record) {
-      throw new ProtocolError(ProtocolErrorCode.InvalidParams, `Unknown taskId: ${taskId}`);
+      throw new ProtocolError(
+        ProtocolErrorCode.InvalidParams,
+        `Unknown taskId: ${taskId}`,
+      );
     }
     if (InspectorClient.isTerminalTaskStatus(record.task.status)) {
       return record.task;
@@ -1012,7 +1047,10 @@ export class InspectorClient extends InspectorClientEventTarget {
             this.addPendingSample(samplingRequest);
           });
         };
-        this.client.setRequestHandler("sampling/createMessage", samplingHandler);
+        this.client.setRequestHandler(
+          "sampling/createMessage",
+          samplingHandler,
+        );
         if (this.receiverTasks) {
           this.installReceiverTaskResponseBypass(
             "sampling/createMessage",
@@ -2001,7 +2039,14 @@ export class InspectorClient extends InspectorClientEventTarget {
       result as CallToolResult,
     );
     if (outputValidationError && !options?.skipOutputValidation) {
-      throw new Error(outputValidationError);
+      // Match the prior contract: on v1 a strict output-schema violation
+      // surfaced as the SDK's typed `McpError`/`ProtocolError` (code
+      // InvalidParams), not a bare Error — so downstream code that branches on
+      // `instanceof ProtocolError` / `error.code` keeps working.
+      throw new ProtocolError(
+        ProtocolErrorCode.InvalidParams,
+        outputValidationError,
+      );
     }
 
     const invocation: ToolCallInvocation = {
@@ -2161,6 +2206,14 @@ export class InspectorClient extends InspectorClientEventTarget {
     );
     // The SDK registers the progress handler synchronously while constructing
     // the request promise (before this await), so the new key is present now.
+    // ASSUMES SERIAL CONSTRUCTION: `find` takes the first key not present in the
+    // pre-request snapshot, which is unambiguous only because no OTHER request
+    // registers a progress handler between the snapshot and this request's
+    // synchronous registration. Tool calls are user-driven and serial, so that
+    // holds today; if concurrent task-augmented calls are ever constructed in
+    // the same microtask window, two subscription ids could cross-wire and this
+    // must move to an SDK-supported correlation (see the delete-when-native note
+    // on `installReceiverTaskResponseBypass`).
     const progressSubscriptionId = requestOptions.onprogress
       ? [...progressHandlers.keys()].find((k) => !keysBeforeRequest.has(k))
       : undefined;

core/mcp/inspectorClientEventTarget.ts

@@ -24,7 +24,17 @@ import type {
   ResourceReadInvocation,
   ResourceTemplateReadInvocation,
 } from "./types.js";
-import type { Tool, ServerCapabilities, Implementation, Root, Progress, ProgressToken, Task, CallToolResult, ProtocolError } from "@modelcontextprotocol/client";
+import type {
+  Tool,
+  ServerCapabilities,
+  Implementation,
+  Root,
+  Progress,
+  ProgressToken,
+  Task,
+  CallToolResult,
+  ProtocolError,
+} from "@modelcontextprotocol/client";
 import type { SamplingCreateMessage } from "./samplingCreateMessage.js";
 import type { ElicitationCreateMessage } from "./elicitationCreateMessage.js";
 import type { JsonValue } from "../json/jsonUtils.js";

core/mcp/inspectorClientProtocol.ts

@@ -20,7 +20,17 @@ import type {
   PromptGetInvocation,
   ToolCallInvocation,
 } from "./types.js";
-import type { ClientCapabilities, Implementation, LoggingLevel, Prompt, Resource, ResourceTemplateType as ResourceTemplate, ServerCapabilities, Task, Tool } from "@modelcontextprotocol/client";
+import type {
+  ClientCapabilities,
+  Implementation,
+  LoggingLevel,
+  Prompt,
+  Resource,
+  ResourceTemplateType as ResourceTemplate,
+  ServerCapabilities,
+  Task,
+  Tool,
+} from "@modelcontextprotocol/client";
 import type { JsonValue } from "../json/jsonUtils.js";
 import type { InspectorClientEventTarget } from "./inspectorClientEventTarget.js";
 import type { SamplingCreateMessage } from "./samplingCreateMessage.js";

core/mcp/messageTrackingTransport.ts

@@ -1,6 +1,17 @@
-import type { Transport, TransportSendOptions } from "@modelcontextprotocol/client";
-import type { JSONRPCMessage, MessageExtraInfo } from "@modelcontextprotocol/client";
-import type { JSONRPCRequest, JSONRPCNotification, JSONRPCResultResponse, JSONRPCErrorResponse } from "@modelcontextprotocol/client";
+import type {
+  Transport,
+  TransportSendOptions,
+} from "@modelcontextprotocol/client";
+import type {
+  JSONRPCMessage,
+  MessageExtraInfo,
+} from "@modelcontextprotocol/client";
+import type {
+  JSONRPCRequest,
+  JSONRPCNotification,
+  JSONRPCResultResponse,
+  JSONRPCErrorResponse,
+} from "@modelcontextprotocol/client";
 import type { MessageOrigin } from "./types.js";
 
 export interface MessageTrackingCallbacks {
@@ -21,10 +32,7 @@ export class MessageTrackingTransport implements Transport {
   private callbacks: MessageTrackingCallbacks;
   private negotiatedProtocolVersion?: string;
 
-  constructor(
-    baseTransport: Transport,
-    callbacks: MessageTrackingCallbacks,
-  ) {
+  constructor(baseTransport: Transport, callbacks: MessageTrackingCallbacks) {
     this.baseTransport = baseTransport;
     this.callbacks = callbacks;
   }

core/mcp/oauthManager.ts

@@ -286,8 +286,7 @@ export class OAuthManager {
     try {
       if (this.isEnterpriseManaged()) {
         const emaConfig = await this.getEmaFlowConfig();
-        const scopeForMint =
-          this.pendingAuthorizationScope ?? emaConfig.scope;
+        const scopeForMint = this.pendingAuthorizationScope ?? emaConfig.scope;
         const config = scopeForMint
           ? { ...emaConfig, scope: scopeForMint }
           : emaConfig;
@@ -449,7 +448,9 @@ export class OAuthManager {
    */
   async refreshEnterpriseManagedTokens(): Promise<boolean> {
     if (!this.isEnterpriseManaged()) return false;
-    const tokens = await refreshEmaResourceTokens(await this.getEmaFlowConfig());
+    const tokens = await refreshEmaResourceTokens(
+      await this.getEmaFlowConfig(),
+    );
     return tokens !== undefined;
   }
 

core/mcp/remote/node/tokenAuthProvider.ts

@@ -1,5 +1,9 @@
 import type { OAuthClientProvider } from "@modelcontextprotocol/client";
-import type { OAuthClientInformation, OAuthClientMetadata, OAuthTokens } from "@modelcontextprotocol/client";
+import type {
+  OAuthClientInformation,
+  OAuthClientMetadata,
+  OAuthTokens,
+} from "@modelcontextprotocol/client";
 import type { RemoteAuthState } from "../types.js";
 
 const REMOTE_OAUTH_STUB_METADATA: OAuthClientMetadata = {

core/mcp/remote/remoteClientTransport.ts

@@ -3,8 +3,14 @@
  * Pure TypeScript; works in browser, Deno, or Node.
  */
 
-import type { Transport, TransportSendOptions } from "@modelcontextprotocol/client";
-import type { JSONRPCMessage, MessageExtraInfo } from "@modelcontextprotocol/client";
+import type {
+  Transport,
+  TransportSendOptions,
+} from "@modelcontextprotocol/client";
+import type {
+  JSONRPCMessage,
+  MessageExtraInfo,
+} from "@modelcontextprotocol/client";
 import type { InspectorServerSettings, StderrLogEntry } from "../types.js";
 import type { FetchRequestEntryBase } from "../types.js";
 import type {

core/mcp/samplingCreateMessage.ts

@@ -1,4 +1,7 @@
-import type { CreateMessageRequest, CreateMessageResult } from "@modelcontextprotocol/client";
+import type {
+  CreateMessageRequest,
+  CreateMessageResult,
+} from "@modelcontextprotocol/client";
 import { RELATED_TASK_META_KEY } from "@modelcontextprotocol/client";
 
 export type { CreateMessageRequest, CreateMessageResult };

core/mcp/serverList.ts

@@ -106,9 +106,7 @@ type StoredInspectorFields = Pick<
 export function envRecordToPairs(
   env: Record<string, string> | undefined,
 ): { key: string; value: string }[] {
-  return env
-    ? Object.entries(env).map(([key, value]) => ({ key, value }))
-    : [];
+  return env ? Object.entries(env).map(([key, value]) => ({ key, value })) : [];
 }
 
 /**
@@ -232,9 +230,7 @@ export function inspectorSettingsToStoredFields(
     out.headers = headersRecord;
   }
 
-  const metadataFiltered = settings.metadata.filter(
-    (m) => m.key.trim() !== "",
-  );
+  const metadataFiltered = settings.metadata.filter((m) => m.key.trim() !== "");
   if (metadataFiltered.length > 0) {
     out.metadata = metadataFiltered;
   }
@@ -333,9 +329,7 @@ export const INSPECTOR_FIELD_KEYS = new Set(
  * `satisfies` constraint above forces the map update, which propagates
  * here.
  */
-export function stripInspectorFields(
-  stored: StoredMCPServer,
-): MCPServerConfig {
+export function stripInspectorFields(stored: StoredMCPServer): MCPServerConfig {
   const out: Record<string, unknown> = {};
   for (const [k, v] of Object.entries(
     stored as unknown as Record<string, unknown>,
@@ -361,7 +355,9 @@ export function mcpConfigToServerEntries(config: MCPConfig): ServerEntry[] {
     // `InspectorServerSettings` only.
     const inspectorFields: StoredInspectorFields = {};
     const sdkOnly: Record<string, unknown> = {};
-    for (const [k, v] of Object.entries(raw as unknown as Record<string, unknown>)) {
+    for (const [k, v] of Object.entries(
+      raw as unknown as Record<string, unknown>,
+    )) {
       if (INSPECTOR_FIELD_KEYS.has(k as keyof StoredInspectorFields)) {
         (inspectorFields as Record<string, unknown>)[k] = v;
       } else {

core/mcp/state/managedListState.ts

@@ -194,9 +194,10 @@ export abstract class ManagedListState<
    * concrete subclass event maps keep the call sites type-safe.
    */
   private emit(type: keyof M, detail: unknown): void {
-    (
-      this.dispatchTypedEvent as unknown as (t: keyof M, d: unknown) => void
-    )(type, detail);
+    (this.dispatchTypedEvent as unknown as (t: keyof M, d: unknown) => void)(
+      type,
+      detail,
+    );
   }
 
   private setListChanged(value: boolean): void {

core/mcp/toolOutputValidation.ts

@@ -1,5 +1,8 @@
 import type { CallToolResult, Tool } from "@modelcontextprotocol/client";
-import type { JsonSchemaType, jsonSchemaValidator } from "@modelcontextprotocol/client";
+import type {
+  JsonSchemaType,
+  jsonSchemaValidator,
+} from "@modelcontextprotocol/client";
 
 /**
  * Validate a delivered tool result's `structuredContent` against the tool's

core/mcp/types.ts

@@ -1,4 +1,23 @@
-import type { CallToolResult, ClientNotification, ClientRequest, GetPromptResult, Implementation, JSONRPCErrorResponse, JSONRPCNotification, JSONRPCRequest, JSONRPCResultResponse, LoggingLevel, Prompt, ReadResourceResult, Resource, Root, ServerCapabilities, ServerNotification, ServerRequest, Tool } from "@modelcontextprotocol/client";
+import type {
+  CallToolResult,
+  ClientNotification,
+  ClientRequest,
+  GetPromptResult,
+  Implementation,
+  JSONRPCErrorResponse,
+  JSONRPCNotification,
+  JSONRPCRequest,
+  JSONRPCResultResponse,
+  LoggingLevel,
+  Prompt,
+  ReadResourceResult,
+  Resource,
+  Root,
+  ServerCapabilities,
+  ServerNotification,
+  ServerRequest,
+  Tool,
+} from "@modelcontextprotocol/client";
 import type { Client } from "@modelcontextprotocol/client";
 import type { OAuthClientProvider } from "@modelcontextprotocol/client";
 import type { Transport } from "@modelcontextprotocol/client";
@@ -149,7 +168,9 @@ export type ConnectionStatus =
  * (see InspectorClient's `onclose` handler, #1490). A bare `=== "disconnected"`
  * check would therefore tear down in one ordering but not the other.
  */
-export function isTerminalStatus(status: ConnectionStatus | undefined): boolean {
+export function isTerminalStatus(
+  status: ConnectionStatus | undefined,
+): boolean {
   return status === "disconnected" || status === "error";
 }
 

core/mcp/urlElicitation.ts

@@ -1,4 +1,8 @@
-import { ProtocolErrorCode, ProtocolError, UrlElicitationRequiredError } from "@modelcontextprotocol/client";
+import {
+  ProtocolErrorCode,
+  ProtocolError,
+  UrlElicitationRequiredError,
+} from "@modelcontextprotocol/client";
 import type { ElicitRequestURLParams } from "@modelcontextprotocol/client";
 
 export type { ElicitRequestURLParams };
@@ -46,7 +50,10 @@ export function getUrlElicitationsFromError(
   if (error instanceof UrlElicitationRequiredError) {
     return error.elicitations ?? [];
   }
-  if (error instanceof ProtocolError && error.code === ProtocolErrorCode.UrlElicitationRequired) {
+  if (
+    error instanceof ProtocolError &&
+    error.code === ProtocolErrorCode.UrlElicitationRequired
+  ) {
     const data = error.data as
       | { elicitations?: ElicitRequestURLParams[] }
       | undefined;