fix: eliminate 8 as any in MCP handlers, structured output, and stream events

- Group A: Add : () => AnyObjectSchema type annotations to MCP notification
  schema constants (useIdeSelection, useIdeLogging, usePrompts, channelNotification)
- Group B: Add isStructuredOutputAttachmentMessage type guard for structured
  output attachment payloads (execAgentHook)
- Group C: Add isMessageDeltaStreamEvent type guard for message_delta
  stream event usage extraction (forkedAgent)

These as any casts also exist in the upstream CCB source — this fix provides
real type safety without changing any runtime behavior.

Author: James-FE

src/entrypoints/cli.tsx

@@ -146,7 +146,7 @@ async function main(): Promise<void> {
         shutdown1PEventLogging,
         logForDebugging,
         registerPermissionHandler(server, handler) {
-          server.setNotificationHandler(ChannelPermissionRequestNotificationSchema() as any, async notification =>
+          server.setNotificationHandler(ChannelPermissionRequestNotificationSchema(), async notification =>
             handler(notification.params),
           );
         },

src/hooks/useIdeLogging.ts

@@ -3,9 +3,10 @@ import { logEvent } from 'src/services/analytics/index.js'
 import { z } from 'zod/v4'
 import type { MCPServerConnection } from '../services/mcp/types.js'
 import { getConnectedIdeClient } from '../utils/ide.js'
+import type { AnyObjectSchema } from '@modelcontextprotocol/sdk/server/zod-compat.js'
 import { lazySchema } from '../utils/lazySchema.js'
 
-const LogEventSchema = lazySchema(() =>
+const LogEventSchema: () => AnyObjectSchema = lazySchema(() =>
   z.object({
     method: z.literal('log_event'),
     params: z.object({
@@ -27,7 +28,7 @@ export function useIdeLogging(mcpClients: MCPServerConnection[]): void {
     if (ideClient) {
       // Register the log event handler
       ideClient.client.setNotificationHandler(
-        LogEventSchema() as any,
+        LogEventSchema(),
         notification => {
           const { eventName, eventData } = notification.params
           logEvent(

src/hooks/useIdeSelection.ts

@@ -6,6 +6,7 @@ import type {
   MCPServerConnection,
 } from '../services/mcp/types.js'
 import { getConnectedIdeClient } from '../utils/ide.js'
+import type { AnyObjectSchema } from '@modelcontextprotocol/sdk/server/zod-compat.js'
 import { lazySchema } from '../utils/lazySchema.js'
 export type SelectionPoint = {
   line: number
@@ -29,7 +30,7 @@ export type IDESelection = {
 }
 
 // Define the selection changed notification schema
-const SelectionChangedSchema = lazySchema(() =>
+const SelectionChangedSchema: () => AnyObjectSchema = lazySchema(() =>
   z.object({
     method: z.literal('selection_changed'),
     params: z.object({
@@ -110,7 +111,7 @@ export function useIdeSelection(
 
     // Register notification handler for selection_changed events
     ideClient.client.setNotificationHandler(
-      SelectionChangedSchema() as any,
+      SelectionChangedSchema(),
       notification => {
         if (currentIDERef.current !== ideClient) {
           return

src/hooks/usePromptsFromClaudeInChrome.tsx

@@ -6,11 +6,12 @@ import { callIdeRpc } from '../services/mcp/client.js';
 import type { ConnectedMCPServer, MCPServerConnection } from '../services/mcp/types.js';
 import type { PermissionMode } from '../types/permissions.js';
 import { CLAUDE_IN_CHROME_MCP_SERVER_NAME, isTrackedClaudeInChromeTabId } from '../utils/claudeInChrome/common.js';
+import type { AnyObjectSchema } from '@modelcontextprotocol/sdk/server/zod-compat.js';
 import { lazySchema } from '../utils/lazySchema.js';
 import { enqueuePendingNotification } from '../utils/messageQueueManager.js';
 
 // Schema for the prompt notification from Chrome extension (JSON-RPC 2.0 format)
-const ClaudeInChromePromptNotificationSchema = lazySchema(() =>
+const ClaudeInChromePromptNotificationSchema: () => AnyObjectSchema = lazySchema(() =>
   z.object({
     method: z.literal('notifications/message'),
     params: z.object({
@@ -48,7 +49,7 @@ export function usePromptsFromClaudeInChrome(
     }
 
     if (mcpClient) {
-      mcpClient.client.setNotificationHandler(ClaudeInChromePromptNotificationSchema() as any, notification => {
+      mcpClient.client.setNotificationHandler(ClaudeInChromePromptNotificationSchema(), notification => {
         if (mcpClientRef.current !== mcpClient) {
           return;
         }

src/services/mcp/channelNotification.ts

@@ -17,6 +17,7 @@
  */
 
 import type { ServerCapabilities } from '@modelcontextprotocol/sdk/types.js'
+import type { AnyObjectSchema } from '@modelcontextprotocol/sdk/server/zod-compat.js'
 import { z } from 'zod/v4'
 import { type ChannelEntry, getAllowedChannels } from '../../bootstrap/state.js'
 import { CHANNEL_TAG } from '../../constants/xml.js'
@@ -96,23 +97,24 @@ export type ChannelPermissionRequestParams = {
   }
 }
 
-export const ChannelPermissionRequestNotificationSchema = lazySchema(() =>
-  z.object({
-    method: z.literal(CHANNEL_PERMISSION_REQUEST_METHOD),
-    params: z.object({
-      request_id: z.string(),
-      tool_name: z.string(),
-      description: z.string(),
-      input_preview: z.string(),
-      channel_context: z
-        .object({
-          source_server: z.string().optional(),
-          chat_id: z.string().optional(),
-        })
-        .optional(),
+export const ChannelPermissionRequestNotificationSchema: () => AnyObjectSchema =
+  lazySchema(() =>
+    z.object({
+      method: z.literal(CHANNEL_PERMISSION_REQUEST_METHOD),
+      params: z.object({
+        request_id: z.string(),
+        tool_name: z.string(),
+        description: z.string(),
+        input_preview: z.string(),
+        channel_context: z
+          .object({
+            source_server: z.string().optional(),
+            chat_id: z.string().optional(),
+          })
+          .optional(),
+      }),
     }),
-  }),
-)
+  )
 
 /**
  * Meta keys become XML attribute NAMES — a crafted key like

src/utils/forkedAgent.ts

@@ -20,10 +20,14 @@ import {
 } from '../services/analytics/index.js'
 import { accumulateUsage, updateUsage } from '../services/api/claude.js'
 import { EMPTY_USAGE, type NonNullableUsage } from '@ant/model-provider'
+import type {
+  BetaRawMessageDeltaEvent,
+  BetaRawMessageStreamEvent,
+} from '@anthropic-ai/sdk/resources/beta/messages/messages.js'
 import type { ToolUseContext } from '../Tool.js'
 import type { AgentDefinition } from '@claude-code-best/builtin-tools/tools/AgentTool/loadAgentsDir.js'
 import type { AgentId } from '../types/ids.js'
-import type { Message } from '../types/message.js'
+import type { Message, StreamEvent } from '../types/message.js'
 import { createChildAbortController } from './abortController.js'
 import { logForDebugging } from './debug.js'
 import { cloneFileStateCache } from './fileStateCache.js'
@@ -492,6 +496,24 @@ export function createSubagentContext(
  * })
  * ```
  */
+
+type StreamEventMessage = StreamEvent & {
+  type: 'stream_event'
+  event: BetaRawMessageStreamEvent
+}
+
+function isMessageDeltaStreamEvent(
+  message: Message | StreamEvent,
+): message is StreamEventMessage & { event: BetaRawMessageDeltaEvent } {
+  return (
+    message.type === 'stream_event' &&
+    typeof (message as StreamEventMessage).event === 'object' &&
+    (message as StreamEventMessage).event !== null &&
+    'type' in (message as StreamEventMessage).event &&
+    (message as StreamEventMessage).event.type === 'message_delta'
+  )
+}
+
 export async function runForkedAgent({
   promptMessages,
   cacheSafeParams,
@@ -562,15 +584,8 @@ export async function runForkedAgent({
     })) {
       // Extract real usage from message_delta stream events (final usage per API call)
       if (message.type === 'stream_event') {
-        if (
-          'event' in message &&
-          (message as any).event?.type === 'message_delta' &&
-          (message as any).event.usage
-        ) {
-          const turnUsage = updateUsage(
-            { ...EMPTY_USAGE },
-            (message as any).event.usage,
-          )
+        if (isMessageDeltaStreamEvent(message)) {
+          const turnUsage = updateUsage({ ...EMPTY_USAGE }, message.event.usage)
           totalUsage = accumulateUsage(totalUsage, turnUsage)
         }
         continue

src/utils/hooks/execAgentHook.ts

@@ -8,7 +8,12 @@ import { type Tool, toolMatchesName } from '../../Tool.js'
 import { SYNTHETIC_OUTPUT_TOOL_NAME } from '@claude-code-best/builtin-tools/tools/SyntheticOutputTool/SyntheticOutputTool.js'
 import { ALL_AGENT_DISALLOWED_TOOLS } from '../../tools.js'
 import { asAgentId } from '../../types/ids.js'
-import type { Message } from '../../types/message.js'
+import type {
+  AttachmentMessage,
+  Message,
+  RequestStartEvent,
+  StreamEvent,
+} from '../../types/message.js'
 import { createAbortController } from '../abortController.js'
 import { createAttachmentMessage } from '../attachments.js'
 import { createCombinedAbortSignal } from '../combinedAbortSignal.js'
@@ -30,6 +35,24 @@ import {
 } from './hookHelpers.js'
 import { clearSessionHooks } from './sessionHooks.js'
 
+type QueryMessage = Message | StreamEvent | RequestStartEvent
+
+type StructuredOutputAttachment = {
+  type: 'structured_output'
+  data: unknown
+  [key: string]: unknown
+}
+
+type StructuredOutputAttachmentMessage =
+  AttachmentMessage<StructuredOutputAttachment>
+
+function isStructuredOutputAttachmentMessage(
+  message: QueryMessage,
+): message is StructuredOutputAttachmentMessage {
+  if (message.type !== 'attachment') return false
+  return (message as Message).attachment?.type === 'structured_output'
+}
+
 /**
  * Execute an agent-based hook using a multi-turn LLM query
  */
@@ -209,13 +232,8 @@ When done, return your result using the ${SYNTHETIC_OUTPUT_TOOL_NAME} tool with:
         }
 
         // Check for structured output in attachments
-        if (
-          message.type === 'attachment' &&
-          (message as any).attachment.type === 'structured_output'
-        ) {
-          const parsed = hookResponseSchema().safeParse(
-            (message as any).attachment.data,
-          )
+        if (isStructuredOutputAttachmentMessage(message)) {
+          const parsed = hookResponseSchema().safeParse(message.attachment.data)
           if (parsed.success) {
             structuredOutputResult = parsed.data
             logForDebugging(