feat(v3): T19-T20 模型池设置 UI + 智能体页 + 指标分账卡

- 设置页「模型池」区块：三角色指派下拉、条目表格（档位徽标/单价/启用/测试/编辑/删除）、
  内联添加表单（模型列表探测 datalist，api_key 留空保留原值）
- 新增「🤖 智能体」页 /agent：任务输入 + 池模型选择、工具调用时间轴
  （round/tool_call/tool_result/usage/final）、左侧工作区文件浏览与预览
- 指标页「按模型分账」卡片（v2.by_model 表格）
- 修复：SSE final 后 EventSource 自动重连回放导致的事件重复渲染（终态即关闭+回放拦截）

webapp/src/api/index.ts

@@ -246,6 +246,161 @@ export function watchDownload(url: string) {
   }
 }
 
+// ── 模型池（多价位异构模型） ─────────────────────────────────────────────────
+
+export type PoolTier = 'local' | 'budget' | 'premium'
+export type PoolRole = 'architect' | 'worker' | 'agent'
+
+export interface PoolEntry {
+  id: string
+  name: string
+  tier: PoolTier
+  backend: 'mock' | 'llama_server' | 'openai'
+  base_url: string
+  model: string
+  api_key: string
+  api_key_set: boolean
+  price_in: number
+  price_out: number
+  temperature: number
+  max_tokens: number
+  enabled: boolean
+}
+
+export interface PoolData {
+  roles: Record<PoolRole, string>
+  entries: PoolEntry[]
+}
+
+/** GET /pool：读取模型池（api_key 打码） */
+export async function getPool() {
+  const { data } = await http.get<PoolData>('/pool')
+  return data
+}
+
+/** POST /pool：新增或更新条目（api_key 留空 = 保留原值） */
+export async function upsertPoolEntry(entry: Partial<PoolEntry>) {
+  const { data } = await http.post<PoolData>('/pool', entry)
+  return data
+}
+
+/** DELETE /pool/{id} */
+export async function deletePoolEntry(id: string) {
+  const { data } = await http.delete<PoolData>(`/pool/${id}`)
+  return data
+}
+
+/** PUT /pool/roles：指派角色（空串 = 经典设置） */
+export async function setPoolRoles(roles: Partial<Record<PoolRole, string>>) {
+  const { data } = await http.put<PoolData>('/pool/roles', roles)
+  return data
+}
+
+/** POST /pool/{id}/test：条目连通性测试 */
+export async function testPoolEntry(id: string) {
+  const { data } = await http.post<{ ok: boolean; detail?: string }>(`/pool/${id}/test`)
+  return data
+}
+
+/** GET /pool/{id}/models：条目端点下的可用模型列表 */
+export async function listPoolModels(id: string) {
+  const { data } = await http.get<{ models?: ModelInfo[]; error?: string }>(`/pool/${id}/models`)
+  return data
+}
+
+// ── 智能体（工具调用） ───────────────────────────────────────────────────────
+
+export interface AgentEvent {
+  type: 'round' | 'tool_call' | 'tool_result' | 'usage' | 'final'
+  ts?: number
+  round?: number
+  name?: string
+  arguments?: Record<string, unknown>
+  ok?: boolean
+  preview?: string
+  prompt_tokens?: number
+  completion_tokens?: number
+  reason?: string
+  error?: string
+}
+
+export interface AgentStatus {
+  request_id: string
+  task: string
+  model: string
+  state: 'running' | 'done' | 'failed'
+  response: string
+  rounds: number
+  prompt_tokens: number
+  completion_tokens: number
+  error?: string | null
+  started_at?: number
+  finished_at?: number
+}
+
+/** POST /agent：提交智能体任务 */
+export async function startAgent(task: string, poolId?: string) {
+  const { data } = await http.post<{ request_id: string; status: string; model: string }>(
+    '/agent', { task, pool_id: poolId || undefined })
+  return data
+}
+
+/** GET /agent/{id}/status */
+export async function getAgentStatus(requestId: string) {
+  const { data } = await http.get<AgentStatus>(`/agent/${requestId}/status`)
+  return data
+}
+
+/** GET /agent/{id}/events：完整事件列表（刷新恢复用） */
+export async function getAgentEvents(requestId: string) {
+  const { data } = await http.get<AgentEvent[]>(`/agent/${requestId}/events`)
+  return data
+}
+
+/** GET /agent/workspace?path=...：浏览工作区目录 */
+export async function listAgentWorkspace(path = '') {
+  const { data } = await http.get<{
+    ok: boolean
+    entries?: { name: string; type: string; size?: number }[]
+    error?: string
+  }>('/agent/workspace', { params: path ? { path } : {} })
+  return data
+}
+
+/** GET /agent/file?path=...：读取工作区文件 */
+export async function readAgentFile(path: string) {
+  const { data } = await http.get<{ ok: boolean; content: string; truncated: boolean; error?: string }>(
+    '/agent/file', { params: { path } })
+  return data
+}
+
+/** SSE /agent/{id}/stream：订阅智能体过程事件 */
+export function watchAgent(requestId: string) {
+  const es = new EventSource(`/agent/${requestId}/stream`)
+  let finalSeen = false
+  return {
+    subscribe(opts: {
+      onEvent: (ev: AgentEvent) => void
+      onDone: () => void
+    }) {
+      es.addEventListener('message', (ev) => {
+        if (finalSeen) return                // final 后的自动重连回放，忽略
+        const d: AgentEvent = JSON.parse(ev.data)
+        opts.onEvent(d)
+        if (d.type === 'final') {
+          finalSeen = true
+          es.close()                         // 终态即关闭，防止重连回放重复渲染
+          opts.onDone()
+        }
+      })
+      es.addEventListener('error', () => {
+        // 连接中断由浏览器自动重连；final 已 seen 时回放会被上方拦截
+      })
+    },
+    close() { es.close() },
+  }
+}
+
 // ── 辅助：轮询直到完成（用于不需要 SSE 的场景）──────────────────────────────────
 
 export async function pollUntilDone(