diff --git a/src/App.tsx b/src/App.tsx
index 0e28c55..5f8b686 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -11,6 +11,7 @@ import { Workbench } from './components/Workbench'
 import { Workspaces, workspaceShortcuts } from './components/Workspaces'
 import { AgentTracker } from './components/AgentTracker'
 import { SettingsModal } from './components/SettingsModal'
+import { ProjectSettingsModal } from './components/ProjectSettingsModal'
 import { DocViewer } from './components/DocViewer'
 
 // 三栏布局：左（项目会话）/ 中（对话）/ 右（工作台）；分隔条拖拽与超调收起（4.4）。
@@ -146,6 +147,7 @@ export function App() {
       <Workspaces />
       {trackerRunId && <AgentTracker />}
       {ui.settingsOpen && <SettingsModal />}
+      {ui.projectSettingsId && <ProjectSettingsModal />}
       {ui.adminUsersOpen && <AdminUsersModal onClose={() => store.setUI({ adminUsersOpen: false })} />}
       {ui.changePwOpen && <ChangePasswordModal onClose={() => store.setUI({ changePwOpen: false })} />}
       {viewingArtifact && <DocViewer artifact={viewingArtifact} />}
diff --git a/src/api.ts b/src/api.ts
index 07b9988..fce8567 100644
--- a/src/api.ts
+++ b/src/api.ts
@@ -26,7 +26,7 @@ export const api = {
   listConversations: (projectId: string) => auth.fetch(`${BASE}/api/projects/${projectId}/conversations`).then(r => json<Conversation[]>(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)),
-  setConversationFlags: (id: string, flags: { pinned?: boolean; archived?: 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}: ${r.statusText}`) }),
+  setConversationFlags: (id: string, flags: { pinned?: boolean; archived?: boolean; allowCrossRead?: boolean; crossPrivate?: boolean }) => auth.fetch(`${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}: ${r.statusText}`) }),
   me: () => auth.fetch(`${BASE}/api/me`).then(r => json<{ owner: string; name: string; auth: boolean; isAdmin?: boolean; mustChangePassword?: boolean }>(r)),
   // ---- 认证与会话（管理员发放制，R2）----
   login: (owner: string, password: string) => auth.fetch(`${BASE}/api/auth/login`, { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ owner, password }) }).then(async r => {
diff --git a/src/components/Conversation.tsx b/src/components/Conversation.tsx
index 41c8103..2e03c19 100644
--- a/src/components/Conversation.tsx
+++ b/src/components/Conversation.tsx
@@ -272,6 +272,13 @@ export function Conversation() {
           }}>
           {profiles.map(p => <option key={p.id} value={p.id}>{p.name}</option>)}
         </select>
+        <button className="btn ghost" style={{ display: 'inline-flex', alignItems: 'center', gap: 4 }}
+          title={conversation?.allowCrossRead === false
+            ? '本会话不读取其他会话记录（点击开启）'
+            : '本会话可读取同项目其他会话记录（需项目设置开启跨会话读取；点击关闭）'}
+          onClick={() => currentConvId && store.setCrossFlags(currentConvId, { allowCrossRead: conversation?.allowCrossRead === false })}>
+          <Icon name="users" size={13} />跨读{conversation?.allowCrossRead === false ? '·关' : '·开'}
+        </button>
         <span title={connected ? '事件流已连接' : '事件流重连中'} className={`conn-dot ${connected ? 'on' : 'off'}`} />
         {active && <button className="btn ghost" onClick={() => store.cancelActive()}>停止</button>}
       </div>
diff --git a/src/components/ProjectSettingsModal.tsx b/src/components/ProjectSettingsModal.tsx
new file mode 100644
index 0000000..1b9a4e1
--- /dev/null
+++ b/src/components/ProjectSettingsModal.tsx
@@ -0,0 +1,86 @@
+// 项目设置面板（提案 2026-09-30-cross-session-reading）：首个项目级设置 UI。
+// schema 驱动渲染 project scope（4.9 覆盖链：system → user → project），
+// 写 putProjectSettings；后续项目级设置项经 settings schema 自动出现，零开发。
+import { useEffect, useMemo, useState } from 'react'
+import { api } from '../api'
+import { store, useStore } from '../store'
+import type { SettingDesc } from '../contracts'
+import { SettingsShell, Btn, EmptyState } from '@ui'
+import { SettingInput, flatten, unflatten, groupNames } from './SettingsModal'
+
+export function ProjectSettingsModal() {
+  const projectId = useStore(s => s.ui.projectSettingsId)
+  const projects = useStore(s => s.projects)
+  const project = projects.find(p => p.id === projectId)
+  const [schema, setSchema] = useState<SettingDesc[]>([])
+  const [draft, setDraft] = useState<Record<string, any>>({})
+  const [loaded, setLoaded] = useState(false)
+  const [saved, setSaved] = useState(false)
+
+  useEffect(() => {
+    if (!projectId) return
+    setLoaded(false)
+    api.getSettings(projectId).then(s => {
+      setSchema(s.schema)
+      setDraft(flatten(s.project))
+      setLoaded(true)
+    }).catch(() => undefined)
+  }, [projectId])
+
+  const groups = useMemo(() => {
+    const g: Record<string, SettingDesc[]> = {}
+    for (const d of schema) (g[d.group] ??= []).push(d)
+    return g
+  }, [schema])
+
+  if (!projectId) return null
+
+  const save = async () => {
+    if (!projectId) return
+    try {
+      await api.putProjectSettings(projectId, unflatten(draft))
+      setSaved(true)
+      setTimeout(() => setSaved(false), 1500)
+    } catch (e) {
+      store.toast(`项目设置保存失败：${e}`)
+    }
+  }
+
+  return (
+    <SettingsShell
+      title={`项目设置 · ${project?.name ?? projectId}`}
+      active="project"
+      onSelect={() => undefined}
+      onClose={() => store.openProjectSettings(null)}
+      sections={[{ key: 'project', label: '本项目', icon: 'folder' }]}
+      footer={saved ? <span style={{ color: 'var(--ok)' }}>✓ 已保存</span> : '项目设置覆盖用户设置（new-run 类对新任务生效）'}
+    >
+      <div>
+        {!loaded ? (
+          <EmptyState icon="settings">加载中…</EmptyState>
+        ) : (
+          <>
+            <div className="empty-note" style={{ marginBottom: 10 }}>
+              此处仅保存本项目的覆盖值；留空即沿用用户/系统设置。跨会话读取在「会话协作」组。
+            </div>
+            {Object.entries(groups).map(([g, descs]) => (
+              <div className="settings-group" key={g}>
+                <h4>{groupNames[g] ?? g}</h4>
+                {descs.map(d => (
+                  <div className="setting-row" key={d.key}>
+                    <label title={d.key}>{d.label}</label>
+                    <SettingInput desc={d} value={draft[d.key] ?? ''} onChange={v => setDraft(x => ({ ...x, [d.key]: v }))} />
+                    <span className={`effect-badge effect-${d.effect}`} title={`生效时机：${d.effect}`}>
+                      {d.effect === 'hot' ? '立即' : d.effect === 'new-run' ? '新任务' : '需重启'}
+                    </span>
+                  </div>
+                ))}
+              </div>
+            ))}
+            <Btn variant="primary" icon="check" onClick={save}>保存项目设置</Btn>
+          </>
+        )}
+      </div>
+    </SettingsShell>
+  )
+}
diff --git a/src/components/SettingsModal.tsx b/src/components/SettingsModal.tsx
index e150a39..45edeb7 100644
--- a/src/components/SettingsModal.tsx
+++ b/src/components/SettingsModal.tsx
@@ -7,6 +7,12 @@ import { SettingsShell, Btn, EmptyState } from '@ui'
 
 type Section = 'settings' | 'profiles' | 'plugins'
 
+// 分组显示名（项目设置面板共用）。
+export const groupNames: Record<string, string> = {
+  models: '模型与密钥', runtime: '运行时', context: '上下文', retrieval: '检索',
+  ui: '界面', plugins: '插件目录', crossSession: '会话协作', tools: '工具',
+}
+
 export function SettingsModal() {
   const profiles = useStore(s => s.profiles)
   const [section, setSection] = useState<Section>('settings')
@@ -29,11 +35,6 @@ export function SettingsModal() {
     return g
   }, [schema])
 
-  const groupNames: Record<string, string> = {
-    models: '模型与密钥', runtime: '运行时', context: '上下文', retrieval: '检索',
-    ui: '界面', plugins: '插件目录',
-  }
-
   const save = async () => {
     const values = unflatten(draft)
     await api.putUserSettings(values)
@@ -83,7 +84,7 @@ export function SettingsModal() {
   )
 }
 
-function SettingInput({ desc, value, onChange }: { desc: SettingDesc; value: any; onChange: (v: any) => void }) {
+export function SettingInput({ desc, value, onChange }: { desc: SettingDesc; value: any; onChange: (v: any) => void }) {
   if (desc.type === 'boolean') {
     return <input type="checkbox" checked={value === true || value === 'true'} onChange={e => onChange(e.target.checked)} />
   }
@@ -106,12 +107,12 @@ function flat(m: Record<string, any>, prefix: string, out: Record<string, any>)
     else out[key] = v
   }
 }
-function flatten(m: Record<string, any>): Record<string, any> {
+export function flatten(m: Record<string, any>): Record<string, any> {
   const out: Record<string, any> = {}
   flat(m, '', out)
   return out
 }
-function unflatten(flatMap: Record<string, any>): Record<string, any> {
+export function unflatten(flatMap: Record<string, any>): Record<string, any> {
   const out: Record<string, any> = {}
   for (const [k, v] of Object.entries(flatMap)) {
     if (v === '' || v === undefined) continue // 空串不覆盖（密钥未修改）
diff --git a/src/components/TaskSidebar.tsx b/src/components/TaskSidebar.tsx
index 398c53f..60b71fa 100644
--- a/src/components/TaskSidebar.tsx
+++ b/src/components/TaskSidebar.tsx
@@ -93,6 +93,10 @@ export function TaskSidebar() {
       <button className="tsb-row-act" title={t.archived ? '恢复' : '归档'} onClick={e => { e.stopPropagation(); store.archiveTask(t.id, !t.archived) }}>
         <Icon name={t.archived ? 'undo' : 'archive'} size={13} />
       </button>
+      <button className={`tsb-row-act ${t.crossPrivate ? 'active' : ''}`} title={t.crossPrivate ? '私有会话：不被其他会话读取（点击取消）' : '设为私有（不被其他会话读取）'}
+        onClick={e => { e.stopPropagation(); store.setCrossFlags(t.id, { crossPrivate: !t.crossPrivate }) }}>
+        <Icon name="shield" size={13} />
+      </button>
     </span>
   )
 
@@ -101,6 +105,7 @@ export function TaskSidebar() {
       onClick={() => store.openTask(t.id)}
       onContextMenu={e => { e.preventDefault(); setMenu({ kind: `row:${t.id}`, anchor: e.currentTarget as HTMLElement }) }}>
       <span className="tsb-task-t" title={t.title}>{t.title || '未命名任务'}</span>
+      {t.crossPrivate && <span className="tsb-pbadge" title="私有：不被其他会话读取"><Icon name="shield" size={11} /></span>}
       {badge && <span className="tsb-pbadge">{badge}</span>}
       <span className="tsb-task-tm">{relativeTime(t.updatedAt)}</span>
       {rowActions(t)}
@@ -176,6 +181,7 @@ export function TaskSidebar() {
                 <span className="tsb-group-name" title={g.label}>{g.label}</span>
                 <span className="tsb-group-cnt">{g.tasks.length}</span>
                 <span style={{ flex: 1 }} />
+                <button className="tsb-group-add" title="项目设置（含跨会话读取）" onClick={e => { e.stopPropagation(); if (g.projectId) store.openProjectSettings(g.projectId) }}><Icon name="settings" size={13} /></button>
                 <button className="tsb-group-add" title="在此项目新建任务" onClick={e => { e.stopPropagation(); store.createTask(g.projectId) }}><Icon name="plus" size={13} /></button>
               </div>
             ) : (
@@ -224,6 +230,9 @@ export function TaskSidebar() {
           <MenuItem icon="pin" onClick={() => { store.pinTask(rowTask.id, !rowTask.pinned); setMenu(null) }}>{rowTask.pinned ? '取消置顶' : '置顶'}</MenuItem>
           <MenuItem icon={rowTask.archived ? 'undo' : 'archive'} onClick={() => { store.archiveTask(rowTask.id, !rowTask.archived); setMenu(null) }}>{rowTask.archived ? '恢复（移出归档）' : '归档'}</MenuItem>
           <div className="tsb-menu-div" />
+          <MenuItem icon="shield" onClick={() => { store.setCrossFlags(rowTask.id, { crossPrivate: !rowTask.crossPrivate }); setMenu(null) }}>{rowTask.crossPrivate ? '取消私有（可被其他会话读取）' : '设为私有（不被其他会话读取）'}</MenuItem>
+          <MenuItem icon="users" onClick={() => { store.setCrossFlags(rowTask.id, { allowCrossRead: rowTask.allowCrossRead === false }); setMenu(null) }}>{rowTask.allowCrossRead === false ? '开启读取其他会话' : '关闭读取其他会话'}</MenuItem>
+          <div className="tsb-menu-div" />
           <MenuItem icon="clock" onClick={() => { store.setUI({ taskOrg: 'timeline' }); setMenu(null) }}>按时间线查看</MenuItem>
         </>}
       </Menu>
diff --git a/src/contracts.ts b/src/contracts.ts
index ec2b011..2cdbb20 100644
--- a/src/contracts.ts
+++ b/src/contracts.ts
@@ -15,6 +15,7 @@ export interface Project {
 export interface Conversation {
   id: ID; projectId: ID; owner?: ID; title: string; profileId?: ID;
   pinned?: boolean; archived?: boolean;
+  allowCrossRead?: boolean; crossPrivate?: boolean;
   createdAt: string; updatedAt: string;
 }
 
diff --git a/src/store.ts b/src/store.ts
index 0006b8f..f87436e 100644
--- a/src/store.ts
+++ b/src/store.ts
@@ -40,6 +40,7 @@ export interface UIState {
   lastProjectId: string | null
   adminUsersOpen: boolean
   changePwOpen: boolean
+  projectSettingsId: string | null
 }
 
 export interface Me { owner: string; name: string; auth: boolean; isAdmin?: boolean; mustChangePassword?: boolean }
@@ -86,6 +87,7 @@ const DEFAULT_UI: UIState = {
   lastProjectId: null,
   adminUsersOpen: false,
   changePwOpen: false,
+  projectSettingsId: null,
 }
 
 function loadUI(): UIState {
@@ -209,6 +211,13 @@ export const store = {
     store.refreshTasks()
   },
 
+  // 跨会话标记（提案 2026-09-30-cross-session-reading）：出站 allowCrossRead / 入站 crossPrivate。
+  async setCrossFlags(convId: string, flags: { allowCrossRead?: boolean; crossPrivate?: boolean }) {
+    const tasks = state.tasks.map(t => t.id === convId ? { ...t, ...flags } : t)
+    set({ tasks })
+    try { await api.setConversationFlags(convId, flags) } catch (e) { store.toast(`跨会话设置失败：${e}`); store.refreshTasks() }
+  },
+
   async openConversation(convId: string) {
     if (sse) { sse.close(); sse = null }
     set({ currentConvId: convId, messages: [], runs: [], activeHitl: [], lastSeq: 0, live: null, plan: null, todos: null, cards: [] })
@@ -494,6 +503,7 @@ export const store = {
   openTracker(runId: string) { setUI({ trackerRunId: runId }) },
   viewArtifact(a: Artifact | null) { setUI({ viewingArtifact: a }) },
   openSettings(open: boolean) { setUI({ settingsOpen: open }) },
+  openProjectSettings(id: string | null) { setUI({ projectSettingsId: id }) },
   toast(msg: string) {
     set({ toast: msg })
     setTimeout(() => { if (state.toast === msg) set({ toast: null }) }, 2600)
diff --git a/tsconfig.tsbuildinfo b/tsconfig.tsbuildinfo
index e4fba48..501abbe 100644
--- a/tsconfig.tsbuildinfo
+++ b/tsconfig.tsbuildinfo
@@ -1 +1 @@
-{"root":["./src/App.tsx","./src/api.ts","./src/auth.ts","./src/contracts.ts","./src/main.tsx","./src/passwords.ts","./src/store.ts","./src/tasklist.ts","./src/components/AdminUsersModal.tsx","./src/components/AgentTracker.tsx","./src/components/Conversation.tsx","./src/components/DocViewer.tsx","./src/components/LoginPage.tsx","./src/components/SettingsModal.tsx","./src/components/TaskSidebar.tsx","./src/components/Workbench.tsx","./src/components/Workspaces.tsx","./test/auth.test.ts","./test/contracts.test.ts","./test/tasklist.test.ts"],"version":"5.9.3"}
\ No newline at end of file
+{"root":["./src/App.tsx","./src/api.ts","./src/auth.ts","./src/contracts.ts","./src/main.tsx","./src/passwords.ts","./src/store.ts","./src/tasklist.ts","./src/components/AdminUsersModal.tsx","./src/components/AgentTracker.tsx","./src/components/Conversation.tsx","./src/components/DocViewer.tsx","./src/components/LoginPage.tsx","./src/components/ProjectSettingsModal.tsx","./src/components/SettingsModal.tsx","./src/components/TaskSidebar.tsx","./src/components/Workbench.tsx","./src/components/Workspaces.tsx","./test/auth.test.ts","./test/contracts.test.ts","./test/tasklist.test.ts"],"version":"5.9.3"}
\ No newline at end of file