fix(server): 支持按 prompt 动态切换 agent

- sessionHandle 添加 --agent spawn 参数和 setAgent() 控制请求
- prompt/prompt_async 路由提取 body.agent 并调用 setAgent
- print.ts 添加 set_agent 控制请求处理
- controlSchemas 添加 SDKControlSetAgentRequestSchema

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/cli/print.ts

@@ -3097,6 +3097,13 @@ function runHeadlessStreaming(
           notifySessionMetadataChanged({ model })
           injectModelSwitchBreadcrumbs(requestedModel, model)
 
+          sendControlResponseSuccess(msg)
+        } else if (msg.request.subtype === 'set_agent') {
+          const agent = typeof msg.request.agent === 'string' ? msg.request.agent : undefined
+          if (agent) {
+            setMainThreadAgentType(agent)
+            saveAgentSetting(agent)
+          }
           sendControlResponseSuccess(msg)
         } else if (msg.request.subtype === 'set_max_thinking_tokens') {
           if (msg.request.max_thinking_tokens === null) {

src/entrypoints/sdk/controlSchemas.ts

@@ -143,6 +143,15 @@ export const SDKControlSetModelRequestSchema = lazySchema(() =>
     .describe('Sets the model to use for subsequent conversation turns.'),
 )
 
+export const SDKControlSetAgentRequestSchema = lazySchema(() =>
+  z
+    .object({
+      subtype: z.literal('set_agent'),
+      agent: z.string().optional(),
+    })
+    .describe('Sets the agent for subsequent conversation turns.'),
+)
+
 export const SDKControlSetMaxThinkingTokensRequestSchema = lazySchema(() =>
   z
     .object({
@@ -556,6 +565,7 @@ export const SDKControlRequestInnerSchema = lazySchema(() =>
     SDKControlInitializeRequestSchema(),
     SDKControlSetPermissionModeRequestSchema(),
     SDKControlSetModelRequestSchema(),
+    SDKControlSetAgentRequestSchema(),
     SDKControlSetMaxThinkingTokensRequestSchema(),
     SDKControlMcpStatusRequestSchema(),
     SDKControlGetContextUsageRequestSchema(),

src/server/routes/session.ts

@@ -373,6 +373,7 @@ export function createSessionRoutes(
         files?: string[]
         images?: unknown[]
         model?: { providerID?: string; modelID?: string }
+        agent?: string
       }>()
 
       const textContent = body.content ?? body.parts
@@ -390,6 +391,10 @@ export function createSessionRoutes(
       if (body.model?.modelID) {
         try { await handle.setModel(body.model.modelID) } catch {}
       }
+      const effectiveAgent = body.agent ?? (agentParts[0] as Record<string, unknown> | undefined)?.name as string | undefined
+      if (effectiveAgent && effectiveAgent !== handle.agent) {
+        try { await handle.setAgent(effectiveAgent) } catch {}
+      }
 
       return ssePrompt(handle, id, content, c, body.parts)
     })
@@ -421,6 +426,7 @@ export function createSessionRoutes(
         files?: string[]
         images?: unknown[]
         model?: { providerID?: string; modelID?: string }
+        agent?: string
       }>()
 
       const textContent = body.content ?? body.parts
@@ -447,6 +453,10 @@ export function createSessionRoutes(
           if (body.model?.modelID) {
             try { await handle.setModel(body.model.modelID) } catch {}
           }
+          const effectiveAgent = body.agent ?? (agentParts[0] as Record<string, unknown> | undefined)?.name as string | undefined
+          if (effectiveAgent && effectiveAgent !== handle.agent) {
+            try { await handle.setAgent(effectiveAgent) } catch {}
+          }
           handle.prompt(content, { parts: body.parts }).catch(() => {})
         } catch {}
       })()

src/server/sessionHandle.ts

@@ -18,6 +18,7 @@ export type SessionHandleOptions = {
   sessionId: string
   cwd: string
   model?: string
+  agent?: string
   permissionMode?: string
   systemPrompt?: string
   resumeSessionId?: string
@@ -39,6 +40,7 @@ export class SessionHandle {
   private _status: SessionState = 'starting'
   private _busyStatus: SessionBusyStatus = { type: 'idle' }
   private _model?: string
+  private _agent?: string
   private _providerId?: string
   private _permissionMode?: string
   private _title?: string
@@ -74,6 +76,9 @@ export class SessionHandle {
   get model(): string | undefined {
     return this._model
   }
+  get agent(): string | undefined {
+    return this._agent
+  }
   get permissionMode(): string | undefined {
     return this._permissionMode
   }
@@ -147,6 +152,7 @@ export class SessionHandle {
     this.cwd = opts.cwd
     this.eventBus = opts.eventBus
     this._model = opts.model
+    this._agent = opts.agent
     this._permissionMode = opts.permissionMode ?? 'acceptEdits'
     this.verbose = opts.verbose ?? false
   }
@@ -165,6 +171,7 @@ export class SessionHandle {
       'stream-json',
       ...(this.opts.resumeSessionId ? [] : ['--session-id', this.sessionId]),
       ...(this.opts.model ? ['--model', this.opts.model] : []),
+      ...(this._agent ? ['--agent', this._agent] : []),
       '--permission-mode',
       this._permissionMode,
       '--permission-prompt-tool',
@@ -446,6 +453,11 @@ export class SessionHandle {
     await this.sendControlRequest({ subtype: 'set_model', model })
   }
 
+  async setAgent(agent: string): Promise<void> {
+    this._agent = agent
+    await this.sendControlRequest({ subtype: 'set_agent', agent })
+  }
+
   async setPermissionMode(mode: string): Promise<void> {
     this._permissionMode = mode
     await this.sendControlRequest({ subtype: 'set_permission_mode', mode })