diff --git a/src/api.ts b/src/api.ts
index 4aea859..29ea657 100644
--- a/src/api.ts
+++ b/src/api.ts
@@ -83,6 +83,8 @@ async function json<T>(res: Response): Promise<T> {
   return res.json() as Promise<T>
 }
 
+export type ConversationView = Conversation & { /** 无项目对话：服务端内部项目只承载这一条会话，不出现在项目列表里。 */ scratch?: boolean }
+
 export const api = {
 	permissionCatalog: () => auth.fetch(`${BASE}/api/admin/permissions/catalog`).then(r => json<{ permissions: PermissionDescriptor[] }>(r)).then(d => d.permissions ?? []),
 	listRoles: (request: { query?: string; mode?: 'exact' | 'fuzzy'; status?: 'all' | 'enabled' | 'disabled'; action?: string; cursor?: string; limit?: number } = {}) => {
@@ -117,13 +119,13 @@ export const api = {
 	explainSystemAction: (action: string) => auth.fetch(`${BASE}/api/authz/explain?action=${encodeURIComponent(action)}`).then(r => json<{ allowed: boolean; actionId: string; source?: string; reason?: string; authorityEpoch: number }>(r)),
   listProjects: (signal?: AbortSignal) => auth.fetch(`${BASE}/api/projects`, signal ? { signal } : undefined).then(r => json<Project[]>(r)),
   createProject: (name: string) => auth.fetch(`${BASE}/api/projects`, { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ name }) }).then(r => json<Project>(r)),
-  createScratchSession: (title?: string) => auth.fetch(`${BASE}/api/scratch-sessions`, { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(title ? { title } : {}) }).then(r => json<{ project: Project; conversation: Conversation }>(r)),
+  createScratchSession: (title?: string) => auth.fetch(`${BASE}/api/scratch-sessions`, { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(title ? { title } : {}) }).then(r => json<{ project: Project; conversation: ConversationView }>(r)),
   renameProject: (id: string, name: string) => auth.fetch(`${BASE}/api/projects/${id}`, { method: 'PATCH', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ name }) }).then(r => json<Project>(r)),
   deleteProject: (id: string) => auth.fetch(`${BASE}/api/projects/${id}`, { method: 'DELETE' }).then(checked),
 
-  listConversations: (projectId: string) => auth.fetch(`${BASE}/api/projects/${projectId}/conversations`).then(r => json<Conversation[]>(r)),
+  listConversations: (projectId: string) => auth.fetch(`${BASE}/api/projects/${projectId}/conversations`).then(r => json<ConversationView[]>(r)),
   // 跨项目任务列表（方案 A 侧栏）：默认仅未归档；includeArchived 含归档。
-  listTasks: (includeArchived?: boolean) => auth.fetch(`${BASE}/api/conversations${includeArchived ? '?archived=1' : ''}`).then(r => json<Conversation[]>(r)),
+  listTasks: (includeArchived?: boolean) => auth.fetch(`${BASE}/api/conversations${includeArchived ? '?archived=1' : ''}`).then(r => json<ConversationView[]>(r)),
   setConversationFlags: (id: string, flags: { pinned?: boolean; archived?: boolean; allowCrossRead?: boolean; crossPrivate?: boolean }) => auth.fetch(`${BASE}/api/conversations/${id}`, { method: 'PATCH', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(flags) }).then(r => { if (!r.ok) throw new Error(`${r.status}: ${r.statusText}`) }),
   setPermissionMode: (id: string, permissionMode: string) => auth.fetch(`${BASE}/api/conversations/${id}`, { method: 'PATCH', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ permissionMode }) }).then(r => { if (!r.ok) throw new Error(`${r.status}: ${r.statusText}`) }),
   checkpoints: (id: string, messageId: string) => auth.fetch(`${BASE}/api/conversations/${id}/checkpoints?messageId=${encodeURIComponent(messageId)}`).then(r => json<{ restored?: string[]; skipped?: string[] }>(r)),
@@ -189,7 +191,7 @@ export const api = {
   setConversationProfile: (id: string, profileId: string) => auth.fetch(`${BASE}/api/conversations/${id}`, { method: 'PATCH', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ profileId }) }).then(r => json<Conversation>(r)),
 
   conversationDetail: (id: string) => auth.fetch(`${BASE}/api/conversations/${id}`).then(r =>
-    json<{ conversation: Conversation; messages: Message[]; runs: Run[]; activeHitl: HITLCard[]; lastSeq: number; resumeSeq?: number }>(r)),
+    json<{ conversation: ConversationView; messages: Message[]; runs: Run[]; activeHitl: HITLCard[]; lastSeq: number; resumeSeq?: number }>(r)),
 
   runEventsPage: (convId: string, runId: string, after: number, signal?: AbortSignal) =>
     auth.fetch(`${BASE}/api/conversations/${encodeURIComponent(convId)}/runs/${encodeURIComponent(runId)}/events?after=${after}&limit=500`, { signal })
diff --git a/src/components/TaskSidebar.tsx b/src/components/TaskSidebar.tsx
index 9421142..33eac53 100644
--- a/src/components/TaskSidebar.tsx
+++ b/src/components/TaskSidebar.tsx
@@ -3,9 +3,8 @@
 import { useEffect, useRef, useState } from 'react'
 import { store, useStore } from '../store'
 import { auth } from '../auth'
-import { api } from '../api'
+import { api, type ConversationView } from '../api'
 import { Icon } from '@ui'
-import type { Conversation } from '../contracts'
 import { relativeTime, filterTasks } from '../tasklist'
 import {
   canCreateProject, emptyProjectsNotice, projectCapabilitySummary, projectStage, projectStateLabel, projectWorkError,
@@ -96,7 +95,7 @@ export function TaskSidebar({ onCollapse = store.toggleLeft, onConversationOpen,
   const syncNotice = syncStatus === 'degraded' ? '项目列表同步异常，正在自动重试'
     : syncStatus === 'offline' ? '网络已断开，恢复后自动同步项目列表' : null
 
-  const rowActions = (t: Conversation) => (
+  const rowActions = (t: ConversationView) => (
     <span className="tsb-row-acts">
       <button className="tsb-row-act" title="置顶 / 取消置顶" onClick={e => { e.stopPropagation(); store.pinTask(t.id, !t.pinned) }}><Icon name="pin" size={13} /></button>
       <button className="tsb-row-act" title={t.archived ? '恢复' : '归档'} onClick={e => { e.stopPropagation(); store.archiveTask(t.id, !t.archived) }}>
@@ -118,7 +117,7 @@ export function TaskSidebar({ onCollapse = store.toggleLeft, onConversationOpen,
     onConversationOpen?.()
   }
 
-  const taskRow = (t: Conversation) => (
+  const taskRow = (t: ConversationView) => (
     <div key={t.id} className={`tsb-task ${t.id === currentConvId ? 'active' : ''} ${t.archived ? 'archived' : ''}`}
       onContextMenu={e => { e.preventDefault(); setMenu({ kind: `row:${t.id}`, anchor: e.currentTarget as HTMLElement }) }}>
       <button className="tsb-task-open" onClick={() => { store.openTask(t.id); onConversationOpen?.() }}>
diff --git a/src/contracts.ts b/src/contracts.ts
index 358edfd..41fa4b3 100644
--- a/src/contracts.ts
+++ b/src/contracts.ts
@@ -18,8 +18,6 @@ export interface Conversation {
   allowCrossRead?: boolean; crossPrivate?: boolean;
   permissionMode?: 'default' | 'plan' | 'auto_edit' | '';
   sessionNote?: string;
-  /** 无项目对话：服务端内部项目只承载这一条会话，不出现在项目列表里。 */
-  scratch?: boolean;
   createdAt: string; updatedAt: string;
 }
 
diff --git a/src/store.test.ts b/src/store.test.ts
index 416e752..fad9d66 100644
--- a/src/store.test.ts
+++ b/src/store.test.ts
@@ -4,10 +4,11 @@ import {
   PROJECT_SYNC_INTERVAL_MS, PROJECT_SYNC_RENDER_BUDGET_MS, PROJECT_SYNC_REQUEST_BUDGET_MS,
   createProjectAutoDiscover, projectSyncDelay, store, type ProjectSyncEnv, type ProjectSyncStatus,
 } from './store'
-import type { Conversation, Project } from './contracts'
+import type { ConversationView } from './api'
+import type { Project } from './contracts'
 
 const project = (id: string, owner = 'alice'): Project => ({ id, owner, name: id, createdAt: '', updatedAt: '' })
-const task = (id: string, projectId: string): Conversation => ({ id, projectId, title: id, createdAt: '', updatedAt: '' })
+const task = (id: string, projectId: string): ConversationView => ({ id, projectId, title: id, createdAt: '', updatedAt: '' })
 const response = (value: unknown, status = 200) => new Response(JSON.stringify(value), { status })
 function deferred<T>() {
   let resolve!: (value: T) => void
@@ -39,7 +40,7 @@ function fakeEnv() {
 }
 
 let projects: Project[]
-let tasks: Conversation[]
+let tasks: ConversationView[]
 let requests: { path: string; init?: RequestInit }[]
 let route: (path: string, init?: RequestInit) => Promise<Response>
 
diff --git a/src/store.ts b/src/store.ts
index ec2700c..9fbff05 100644
--- a/src/store.ts
+++ b/src/store.ts
@@ -1,7 +1,7 @@
 // 应用状态：服务端权威（事件 + Query 对账），前端 store 是投影。
 // useSyncExternalStore 驱动；live 流式部件为会话内临时态，run 终态后由消息树对账收敛。
 import { useSyncExternalStore } from 'react'
-import { type AdminZoneSection, type LinkedCapabilities, api, connectEvents } from './api'
+import { type AdminZoneSection, type ConversationView, type LinkedCapabilities, api, connectEvents } from './api'
 import { auth } from './auth'
 import { noProjectError, projectActionError, projectWorkError } from './projectmeta'
 import { applyTextDelta, applyThinkingDelta, applyToolCall, applyToolCallDelta, applyToolResult, applyToolOutput, applyArtifactCreated, applyArtifactUpdated, applyCheck, applyFinalizing, type LiveItem } from './live'
@@ -26,7 +26,6 @@ import type {
   TaskSourceRef,
   AgentProfile,
   Artifact,
-  Conversation,
   HITLCard,
   Message,
   PlanSnapshot,
@@ -116,7 +115,7 @@ interface AppState {
   currentProjectId: string | null
   /** 无项目对话视图：currentProjectId 此时是无项目对话的内部项目，不在 projects 里。 */
   scratchMode: boolean
-  tasks: Conversation[]
+  tasks: ConversationView[]
   me: Me | null
   currentConvId: string | null
   messages: Message[]
@@ -376,9 +375,9 @@ async function bindProject(projectId: string, remember: boolean) {
   await store.refreshArtifacts(projectId)
 }
 
-function latestScratchTask(): Conversation | undefined {
+function latestScratchTask(): ConversationView | undefined {
   return state.tasks.filter(t => t.scratch && !t.archived)
-    .reduce<Conversation | undefined>((latest, t) => !latest || t.updatedAt > latest.updatedAt ? t : latest, undefined)
+    .reduce<ConversationView | undefined>((latest, t) => !latest || t.updatedAt > latest.updatedAt ? t : latest, undefined)
 }
 
 function observeDetail(observations: Record<string, DetailObservation>, id: string, seq = state.lastSeq, terminal = false) {
diff --git a/test/scratch-session.test.ts b/test/scratch-session.test.ts
index f14e872..f7585f3 100644
--- a/test/scratch-session.test.ts
+++ b/test/scratch-session.test.ts
@@ -1,16 +1,17 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import { auth } from '../src/auth'
 import { canCreateProject, store } from '../src/store'
-import type { Conversation, Project } from '../src/contracts'
+import type { ConversationView } from '../src/api'
+import type { Project } from '../src/contracts'
 
 const project = (id: string): Project => ({ id, name: id, createdAt: '', updatedAt: '' })
-const task = (id: string, projectId: string, scratch = false, updatedAt = ''): Conversation =>
+const task = (id: string, projectId: string, scratch = false, updatedAt = ''): ConversationView =>
   ({ id, projectId, title: id, createdAt: '', updatedAt, ...(scratch ? { scratch: true } : {}) })
 const response = (value: unknown, status = 200) => new Response(JSON.stringify(value), { status })
-const detail = (conversation: Conversation) => response({ conversation, messages: [], runs: [], activeHitl: [], lastSeq: 0 })
+const detail = (conversation: ConversationView) => response({ conversation, messages: [], runs: [], activeHitl: [], lastSeq: 0 })
 
 let projects: Project[]
-let tasks: Conversation[]
+let tasks: ConversationView[]
 let me: Record<string, unknown>
 let requests: { path: string; init?: RequestInit }[]
 let scratchCount: number