feat(elicitation): sub-agent proxy + createToolClient chain

- SubAgentToolClient: elicitation/create handler forwarding to onElicit
- ToolRegistry.createToolClient: passes onElicit to connect()
- AgentToolsServer: onElicit chain from server → toolClient → sub-agent
- 127 tests passing

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: a6b8

src/AgentToolsServer.ts

@@ -325,7 +325,21 @@ class AgentToolsServer extends EventEmitter {
         const taskId = randomUUID()
         const query = args.query || JSON.stringify( args )
 
-        const { toolClient } = await toolRegistry.createToolClient( { name: toolName } )
+        const onElicit = mcpServer && toolConfig.elicitation?.enabled
+            ? async ( { message, requestedSchema }: { message: string, requestedSchema: any } ) => {
+                try {
+                    const result = await mcpServer.elicitInput( { message, requestedSchema } )
+
+                    return result
+                } catch( err: any ) {
+                    Logger.error( 'AgentServer', `Elicitation failed: ${err.message}` )
+
+                    return { action: 'cancel' as const }
+                }
+            }
+            : undefined
+
+        const { toolClient } = await toolRegistry.createToolClient( { name: toolName, onElicit } )
 
         if( !toolClient ) {
             return {
@@ -359,19 +373,7 @@ class AgentToolsServer extends EventEmitter {
                     apiKey,
                     answerSchema: agent.answerSchema || null,
                     elicitationConfig: toolConfig.elicitation || undefined,
-                    onElicit: mcpServer && toolConfig.elicitation?.enabled
-                        ? async ( { message, requestedSchema }: { message: string, requestedSchema: any } ) => {
-                            try {
-                                const result = await mcpServer.elicitInput( { message, requestedSchema } )
-
-                                return result
-                            } catch( err: any ) {
-                                Logger.error( 'AgentServer', `Elicitation failed: ${err.message}` )
-
-                                return { action: 'cancel' as const }
-                            }
-                        }
-                        : undefined,
+                    onElicit,
                     onStatus: ( { status, round, message }: { status: string, round: number, message: string } ) => {
                         Logger.info( 'AgentServer', `sync | ${toolName} | ${status} | Round ${round} | ${message}` )
 

src/client/SubAgentToolClient.ts

@@ -1,7 +1,9 @@
 import { Client } from '@modelcontextprotocol/sdk/client/index.js'
 import { StreamableHTTPClientTransport } from '@modelcontextprotocol/sdk/client/streamableHttp.js'
+import { ElicitRequestSchema } from '@modelcontextprotocol/sdk/types.js'
 
-import type { ToolClient, Tool, ToolResult } from '../types/index.js'
+import { Logger } from '../logging/Logger.js'
+import type { ToolClient, Tool, ToolResult, ElicitCallback } from '../types/index.js'
 
 
 class SubAgentToolClient implements ToolClient {
@@ -11,6 +13,7 @@ class SubAgentToolClient implements ToolClient {
     #name: string
     #tools: Map<string, Tool>
     #connected: boolean
+    #onElicit: ElicitCallback | null
 
 
     constructor( { url, name = 'sub-agent' }: { url: string, name?: string } ) {
@@ -20,10 +23,13 @@ class SubAgentToolClient implements ToolClient {
         this.#connected = false
         this.#client = null
         this.#transport = null
+        this.#onElicit = null
     }
 
 
-    async connect() {
+    async connect( { onElicit }: { onElicit?: ElicitCallback } = {} ) {
+        this.#onElicit = onElicit || null
+
         this.#transport = new StreamableHTTPClientTransport(
             new URL( this.#url )
         )
@@ -33,6 +39,23 @@ class SubAgentToolClient implements ToolClient {
             { capabilities: {} }
         )
 
+        if( this.#onElicit ) {
+            const elicitCallback = this.#onElicit
+
+            this.#client.setRequestHandler( ElicitRequestSchema, async ( request: any ) => {
+                const { message, requestedSchema } = request.params
+
+                Logger.debug( 'SubAgentToolClient', `Elicitation request from sub-agent "${this.#name}": ${message}` )
+
+                const response = await elicitCallback( { message, requestedSchema } )
+
+                return {
+                    action: response.action,
+                    content: response.content
+                }
+            } )
+        }
+
         await this.#client.connect( this.#transport )
         this.#connected = true
 

src/registry/ToolRegistry.ts

@@ -2,7 +2,7 @@ import { InProcessToolClient } from '../client/InProcessToolClient.js'
 import { CompositeToolClient } from '../client/CompositeToolClient.js'
 import { SubAgentToolClient } from '../client/SubAgentToolClient.js'
 import { Logger } from '../logging/Logger.js'
-import type { ToolClient } from '../types/index.js'
+import type { ToolClient, ElicitCallback } from '../types/index.js'
 
 
 class ToolRegistry {
@@ -55,7 +55,7 @@ class ToolRegistry {
     }
 
 
-    async createToolClient( { name }: { name: string } ): Promise<{ toolClient: ToolClient | null }> {
+    async createToolClient( { name, onElicit }: { name: string, onElicit?: ElicitCallback } ): Promise<{ toolClient: ToolClient | null }> {
         const { toolConfig } = this.getToolConfig( { name } )
 
         if( !toolConfig ) {
@@ -75,7 +75,7 @@ class ToolRegistry {
                 const client = ToolRegistry.#createClientFromSource( { source } )
 
                 if( client && ( client as any ).connect ) {
-                    await ( client as any ).connect()
+                    await ( client as any ).connect( { onElicit } )
                 }
 
                 return client