One brain, many screens: other AnyBots show and edit the brain's bots

- Brain answers /api/sync (per-screen deltas of settings and messages),
  /api/sync/edit (small edit operations) and /api/sync/act (chat actions).
- Relay forwards host-to-host sync requests within one account (role mirror).
- Desktop: choose a brain in 手機與帳號; its own bots are kept aside; offline
  shows the last copy read-only and reconnects by itself.
- Keys and tokens stay on the brain (redacted and restored on edits).
- Browser tools can run on another computer of the account (computer arg).
- anybot --serve: ANYBOT_DEVICE_LINK=1 and ANYBOT_BRAIN=名稱.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Uirha3oEtWeHh58zA7ErHa

relay/src/main.rs

@@ -499,6 +499,16 @@ impl Relay {
                 }
                 self.forward(target, "POST", "/api/device/run", &HashMap::new(), &req.body, (&me.user, "device"))
             }
+            // 大腦: one AnyBot of the account shows (and edits) another one's bots and chats.
+            (m, ["relay", "hosts", target, "api", "sync", rest @ ..]) => {
+                let Some(me) = self.host(&req) else { return Resp::error(401, "這台電腦的金鑰無效") };
+                let same = self.data.lock().unwrap().hosts.iter().any(|h| h.id == *target && h.user == me.user);
+                if !same || *target == me.id {
+                    return Resp::error(403, "不是同一個帳號的電腦");
+                }
+                let path = if rest.is_empty() { "/api/sync".to_string() } else { format!("/api/sync/{}", rest.join("/")) };
+                self.forward(target, m, &path, &req.query, &req.body, (&me.user, "mirror"))
+            }
             // The phone, through to one of the account's AnyBots.
             (m, ["h", host, rest @ ..]) => {
                 let Some(user) = self.session(&req) else { return Resp::error(401, "請先登入") };

src/agent.rs

@@ -114,6 +114,16 @@ fn target_for(job: &Job, args: &str) -> Result<tools::Target, String> {
     })
 }
 
+/// The other computer (裝置連結) a call names, if it names one.
+fn device_named(job: &Job, args: &str) -> Option<String> {
+    let v = tools::args_of(args);
+    let n = v.get("computer").and_then(|c| c.as_str()).map(str::trim).filter(|c| !c.is_empty())?;
+    job.computers.iter().find(|t| t.name == n).and_then(|t| match &t.place {
+        tools::Place::Device { host } => Some(host.clone()),
+        _ => None,
+    })
+}
+
 /// Rough token count: about 4 Latin characters or 1 Chinese character per token (estimated).
 /// Which screen a computer_use call is for: the one named, else the bot's default when it has a
 /// screen, else the bot's own desktop when there is one, else this Mac.
@@ -321,7 +331,14 @@ pub fn spawn(job: Job, bot_id: u64, tx: Sender<(u64, StreamEvent)>, cancel: Arc<
                 // …and neither does AnyBot's own browser (like Grok Bot's own browser).
                 if call.name == "web_fetch" || (web::is_web_tool(&call.name) && !web::uses_this_computer(&call.name, &call.args)) {
                     send(StreamEvent::ToolStatus(call.id.clone(), ToolStatus::Running));
-                    let (output, ok, img) = web::run_full(&call.name, &call.args, &cancel);
+                    // 裝置連結: the AnyBot browser of another computer (its own logins).
+                    let (output, ok, img) = match device_named(&job, &call.args).filter(|_| call.name != "web_fetch") {
+                        Some(host) => match crate::remote::run_on_device(&host, &call.name, &call.args, &job.via_name) {
+                            Ok(v) => (v["text"].as_str().unwrap_or("").to_string(), v["ok"].as_bool().unwrap_or(false), v["image"].as_str().map(String::from)),
+                            Err(e) => (e, false, None),
+                        },
+                        None => web::run_full(&call.name, &call.args, &cancel),
+                    };
                     send(StreamEvent::ToolStatus(call.id.clone(), if ok { ToolStatus::Done } else { ToolStatus::Failed }));
                     let mut result = Message::tool_result(&call.id, &call.name, &output);
                     result.images.extend(img);

src/app.rs

@@ -33,6 +33,7 @@ mod sidebar_ui;
 mod menu_ui;
 mod vault_ui;
 mod markdown_ui;
+mod mirror_ui;
 
 // Sidebar rules from index.eager-app: defaults `FT={expandedWidth:280}` (@912025),
 // clamp `jT(..,240,400)` (@914394), and the drag rule in `QJe` (@969523):
@@ -197,11 +198,16 @@ pub struct App {
     group_menu_for: Option<String>,
     /// When the launch greeting started.
     splash_at: Option<f64>,
+    /// 大腦: this window shows another AnyBot's bots (a screen), or answers screens (the brain).
+    mir: mirror_ui::Mirror,
+    scr: mirror_ui::Screens,
+    ctx_handle: Option<egui::Context>,
 }
 
 impl App {
     pub fn new(ctx: &egui::Context, screenshot: Option<PathBuf>) -> Self {
-        let demo = screenshot.is_some();
+        // ANYBOT_SHOT_REAL=1: a screenshot of the real data (and connections), not the demo.
+        let demo = screenshot.is_some() && std::env::var("ANYBOT_SHOT_REAL").is_err();
         let state = if demo { State::demo() } else { State::load() };
         let (tx, rx) = channel();
         let mut app = App {
@@ -279,6 +285,9 @@ impl App {
             renaming: None,
             group_menu_for: None,
             splash_at: None,
+            mir: Default::default(),
+            scr: Default::default(),
+            ctx_handle: None,
         };
         crate::i18n::set(&app.state.language);
         app.computers_start();
@@ -593,8 +602,14 @@ impl App {
             let quoted: String = q.lines().take(8).map(|l| format!("> {l}\n")).collect();
             text = format!("{quoted}\n{}", text.trim());
         }
-        self.drafts.insert(bot_id, String::new());
         let attachments = self.take_attachments(bot_id);
+        if self.mir.on {
+            if self.mirror_send(bot_id, text.trim().to_string(), attachments) {
+                self.drafts.insert(bot_id, String::new());
+            }
+            return;
+        }
+        self.drafts.insert(bot_id, String::new());
         // While it works, a new message steers the running turn (the original's `turnSteer`:
         // it doesn't count as a new turn) and reaches the model at its next step.
         if let Some(l) = self.streams.get(&bot_id) {
@@ -609,6 +624,10 @@ impl App {
     }
 
     fn start_reply(&mut self, ctx: &egui::Context, bot_id: u64) {
+        if self.mir.on {
+            self.mirror_act(serde_json::json!({"bot": bot_id, "action": "reply"}));
+            return;
+        }
         let Some(conv) = self.state.bot(bot_id).cloned() else { return };
         // 群組聊天: the next member answers, with its own model, instructions and computers.
         let speaker = if conv.members.is_empty() {
@@ -642,7 +661,8 @@ impl App {
         let default_computer = if names.contains(&b.default_computer) { b.default_computer.clone() } else { crate::model::BOT_COMPUTER_NAME.to_string() };
         let mut tool_specs = appctl::specs();
         tool_specs.extend(tools::specs_for(&names, &default_computer));
-        tool_specs.extend(web::specs());
+        let devices: Vec<String> = computers.iter().filter(|t| matches!(t.place, tools::Place::Device { .. })).map(|t| t.name.clone()).collect();
+        tool_specs.extend(web::specs_for(&devices));
         // Screen tools: the bot's own desktop (when it has one) and this Mac.
         let mut screens = vec![];
         if crate::cloudbox::available() {
@@ -873,6 +893,12 @@ impl App {
     }
 
     fn stop(&mut self, bot_id: u64) {
+        if self.mir.on {
+            if self.streams.contains_key(&bot_id) || self.approvals.contains_key(&bot_id) {
+                self.mirror_act(serde_json::json!({"bot": bot_id, "action": "stop"}));
+            }
+            return;
+        }
         self.approvals.remove(&bot_id);
         if let Some(call) = self.app_pending.remove(&bot_id) {
             let _ = call.reply.send(("已停止".into(), false));
@@ -961,6 +987,17 @@ impl App {
     }
 
     fn answer(&mut self, ctx: &egui::Context, bot_id: u64, answer: ApprovalAnswer) {
+        if self.mir.on {
+            let a = match answer {
+                ApprovalAnswer::Once => "once",
+                ApprovalAnswer::Always(_) => "always",
+                ApprovalAnswer::Reject => "reject",
+            };
+            self.approvals.remove(&bot_id);
+            self.popup_hidden.remove(&bot_id);
+            self.mirror_act(serde_json::json!({"bot": bot_id, "action": "answer", "answer": a}));
+            return;
+        }
         if self.want_direct.replace(false) {
             self.enable_direct_mode();
         }
@@ -1004,6 +1041,10 @@ impl App {
     }
 
     fn regenerate(&mut self, ctx: &egui::Context, bot_id: u64) {
+        if self.mir.on {
+            self.mirror_act(serde_json::json!({"bot": bot_id, "action": "regenerate"}));
+            return;
+        }
         if self.streams.contains_key(&bot_id) {
             return;
         }
@@ -1448,7 +1489,9 @@ impl App {
         // 討論串: put this conversation aside and start fresh; earlier ones can come back.
         if menu_ui::item(ui, p, Icon::NewChat, "開始新對話").clicked() {
             self.stop(id);
-            if let Some(b) = self.state.bot_mut(id) {
+            if self.mir.on {
+                self.mirror_act(serde_json::json!({"bot": id, "action": "new"}));
+            } else if let Some(b) = self.state.bot_mut(id) {
                 if !b.messages.is_empty() {
                     let title = b.messages.iter().find(|m| m.role == Role::User).map(|m| first_line(&m.text, 24)).unwrap_or_else(|| "對話".into());
                     let msgs = std::mem::take(&mut b.messages);
@@ -1465,7 +1508,9 @@ impl App {
                 for (i, title) in threads.iter().enumerate() {
                     if menu_ui::item_text(ui, p, None, title).clicked() {
                         self.stop(id);
-                        if let Some(b) = self.state.bot_mut(id) {
+                        if self.mir.on {
+                            self.mirror_act(serde_json::json!({"bot": id, "action": "restore", "index": i}));
+                        } else if let Some(b) = self.state.bot_mut(id) {
                             let (_, msgs) = b.threads.remove(i);
                             if !b.messages.is_empty() {
                                 let cur_title = b.messages.iter().find(|m| m.role == Role::User).map(|m| first_line(&m.text, 24)).unwrap_or_else(|| "對話".into());
@@ -1564,6 +1609,7 @@ impl App {
                 return;
             };
             self.header(ui, &bot);
+            self.mirror_banner(ui);
             // The composer grows with a long draft: keep room for last frame's height.
             let h_id = egui::Id::unique("composer-height");
             let composer_h: f32 = ui.data(|d| d.get_temp(h_id)).unwrap_or(116.0);
@@ -1964,7 +2010,7 @@ impl App {
                     });
                     let right_w = 28.0 * 2.0 + 8.0 + 4.0;
                     let text_w = (ui.available_width() - right_w).max(60.0);
-                    let hint = t("傳訊息給 {name}").replace("{name}", &bot.name);
+                    let hint = if self.mir.on && !self.mir.online { t("連不到大腦，現在只能看") } else { t("傳訊息給 {name}").replace("{name}", &bot.name) };
                     ui.allocate_ui_with_layout(vec2(text_w, 28.0), Layout::top_down(Align::Min), |ui| {
                         egui::ScrollArea::vertical().id_salt(("composer_scroll", bot.id)).max_height(160.0).show(ui, |ui| {
                             ui.add_space(4.0);
@@ -2957,11 +3003,17 @@ impl App {
     /// Everything that keeps bots working, without drawing (the window runs it every frame;
     /// `anybot --serve` runs it on its own).
     fn background(&mut self, ctx: &egui::Context) {
+        self.remote_start(ctx);
+        self.mirror_tick();
+        // A screen of another AnyBot's brain: its bots work there, not here.
+        if self.mir.on {
+            self.remote_tick(ctx);
+            return;
+        }
         self.drain_events(ctx);
         if !self.demo {
             self.channels_poll(ctx);
         }
-        self.remote_start(ctx);
         self.remote_tick(ctx);
         self.tick_routines(ctx);
         self.watchdog();
@@ -2971,7 +3023,11 @@ impl App {
 
     fn save_if_dirty(&mut self) {
         if self.dirty && !self.demo && (self.streams.is_empty() || self.last_save.elapsed().as_secs() >= 2) {
+            if self.mir.on {
+                self.mirror_save();
+            } else {
                 self.state.save();
+            }
             self.dirty = false;
             self.last_save = Instant::now();
         }
@@ -3033,7 +3089,7 @@ impl App {
             }
             app.drain_events(ctx);
             app.watchdog();
-            let _ = ctx.run_ui(Default::default(), |_| {});
+            ctx.run_ui(Default::default(), |_| {}).textures_delta.clear();
             std::thread::sleep(std::time::Duration::from_millis(100));
         }
         let secs = t0.elapsed().as_secs();
@@ -3081,6 +3137,11 @@ impl App {
                 app.dirty = true;
             }
         }
+        // 手腳: a computer the brain's bots may operate (screen, files, browser).
+        if std::env::var("ANYBOT_DEVICE_LINK").map(|v| v == "1").unwrap_or(false) && !app.state.remote.device_link {
+            app.state.remote.device_link = true;
+            app.dirty = true;
+        }
         app.serve_join();
         app.background(ctx);
         if let Some(port) = crate::remote::lan_port() {
@@ -3095,16 +3156,28 @@ impl App {
             eprintln!("AnyBot：還沒有設定手機密碼或帳號。用 ANYBOT_PHONE_PASSWORD=… 或 ANYBOT_ACCOUNT=網址|帳號 + ANYBOT_ACCOUNT_PASSWORD=… 啟動。");
         }
         let mut last_try = Instant::now();
+        let mut last_brain = Instant::now() - std::time::Duration::from_secs(60);
         loop {
             // The account server may not be up yet (or the account not made yet): keep trying.
             if app.state.remote.host_token.is_empty() && last_try.elapsed().as_secs() >= 30 {
                 last_try = Instant::now();
                 app.serve_join();
             }
+            // ANYBOT_BRAIN=名稱: show that AnyBot's bots instead of running its own.
+            if let Ok(want) = std::env::var("ANYBOT_BRAIN") {
+                if !want.trim().is_empty() && !app.state.remote.host_token.is_empty() && app.state.remote.brain_name != want && last_brain.elapsed().as_secs() >= 20 {
+                    last_brain = Instant::now();
+                    if let Some((id, name, _)) = crate::remote::devices_online(&app.state.remote).into_iter().find(|(_, n, _)| n == want.trim()) {
+                        eprintln!("AnyBot：用「{name}」當大腦，這台當手腳");
+                        app.mir.want = Some((id, name));
+                        app.state.remote.device_link = true;
+                    }
+                }
+            }
             app.background(ctx);
             app.save_if_dirty();
             // egui wants a frame now and then to forget old state; nothing is drawn.
-            let _ = ctx.run_ui(Default::default(), |_| {});
+            ctx.run_ui(Default::default(), |_| {}).textures_delta.clear();
             std::thread::sleep(std::time::Duration::from_millis(if app.streams.is_empty() { 250 } else { 60 }));
         }
     }
@@ -3216,6 +3289,10 @@ impl eframe::App for App {
 
     fn on_exit(&mut self) {
         // Closing mid-reply ends that turn as cancelled, so it isn't left looking stuck.
+        // (On a screen of a brain the bots keep working there.)
+        if self.mir.on {
+            self.streams.clear();
+        }
         let ids: Vec<u64> = self.streams.keys().copied().collect();
         for id in ids {
             self.stop(id);
@@ -3223,10 +3300,14 @@ impl eframe::App for App {
         tools::stop_all();
         crate::cloudbox::shutdown();
         if !self.demo {
+            if self.mir.on {
+                self.mirror_save();
+            } else {
                 self.state.save();
             }
         }
     }
+}
 
 // ---------- helpers ----------
 

src/app/mirror_ui.rs

@@ -0,0 +1,882 @@
+// 大腦: one AnyBot of the account keeps the bots, chats, memory and schedules (the brain, usually
+// `anybot --serve` next to the account server). Every other AnyBot signed in to the account shows
+// the brain's bots in its own window and lends its hands (screen, files, browser) through 裝置連結.
+//
+// The brain side answers "what changed since version N?" per screen: the settings (bots without
+// their chats) when they changed, and for each bot only the messages from the first one that
+// changed. The screen side keeps a copy, sends the person's edits back as small operations, and
+// turns chat actions (send, stop, approve…) into requests. When the brain can't be reached the
+// window stays readable and waits.
+
+use super::*;
+use crate::remote::{self, SyncKind};
+use serde_json::{json, Value};
+use std::hash::{Hash, Hasher};
+use std::sync::atomic::AtomicU64;
+
+/// Settings that belong to each computer, never to the brain.
+const LOCAL_KEYS: &[&str] = &["remote", "theme", "accent", "sidebar_collapsed", "sidebar_width", "selected", "machine_label", "local_execution", "local_never", "messages_send", "messages_no_ask"];
+/// Bot fields the brain alone changes (its chat, and what a turn leaves behind).
+const BOT_RUNTIME: &[&str] = &["id", "messages", "threads", "unread", "last_turn", "context_tokens"];
+/// Stands in for a key or token the brain doesn't hand out.
+pub const REDACTED: &str = "••••（已設定，在大腦上）";
+
+// ---------- shared ----------
+
+/// The settings as JSON: everything but the chats (messages and earlier conversations).
+pub(super) fn config_json(st: &mut State) -> Value {
+    let mut bots = std::mem::take(&mut st.bots);
+    let mut top = serde_json::to_value(&*st).unwrap_or(Value::Null);
+    let mut arr = Vec::with_capacity(bots.len());
+    for b in bots.iter_mut() {
+        let m = std::mem::take(&mut b.messages);
+        let th = std::mem::take(&mut b.threads);
+        arr.push(serde_json::to_value(&*b).unwrap_or(Value::Null));
+        b.messages = m;
+        b.threads = th;
+    }
+    st.bots = bots;
+    top["bots"] = Value::Array(arr);
+    top
+}
+
+/// Keys and tokens stay on the brain.
+fn redact(top: &mut Value) {
+    if let Some(o) = top.as_object_mut() {
+        o.remove("remote");
+    }
+    let hide = |v: &mut Value| {
+        if v.as_str().map(|s| !s.is_empty()).unwrap_or(false) {
+            *v = Value::String(REDACTED.into());
+        }
+    };
+    if let Some(ps) = top["providers"].as_object_mut() {
+        for p in ps.values_mut() {
+            hide(&mut p["api_key"]);
+        }
+    }
+    for c in top["channels"].as_array_mut().into_iter().flatten() {
+        hide(&mut c["token"]);
+    }
+    for m in top["mcp_servers"].as_array_mut().into_iter().flatten() {
+        for k in ["env", "headers"] {
+            for v in m[k].as_object_mut().into_iter().flat_map(|o| o.values_mut()) {
+                hide(v);
+            }
+        }
+    }
+}
+
+/// Put the brain's own keys back wherever an edit still carries the stand-in.
+fn unredact(new: &mut Value, old: &Value) {
+    match new {
+        Value::String(s) if s == REDACTED => *new = old.clone(),
+        Value::Object(o) => {
+            for (k, v) in o.iter_mut() {
+                unredact(v, old.get(k).unwrap_or(&Value::Null));
+            }
+        }
+        Value::Array(a) => {
+            for (i, v) in a.iter_mut().enumerate() {
+                let key = |x: &Value| x.get("id").cloned().filter(|x| !x.is_null()).or_else(|| x.get("name").cloned());
+                let twin = old.as_array().and_then(|olds| match key(v) {
+                    Some(k) => olds.iter().find(|o| key(o).as_ref() == Some(&k)),
+                    None => olds.get(i),
+                });
+                unredact(v, twin.unwrap_or(&Value::Null));
+            }
+        }
+        _ => {}
+    }
+}
+
+/// A cheap fingerprint of one message: enough to see it changed (streaming, a tool finishing…).
+fn msg_sig(m: &Message) -> u64 {
+    let mut h = std::collections::hash_map::DefaultHasher::new();
+    (m.role as u8, m.text.len(), m.thinking.len(), m.error, m.summary, m.images.len(), m.attachments.len(), m.at, &m.tool_call_id, &m.reactions).hash(&mut h);
+    m.text.chars().rev().take(48).collect::<String>().hash(&mut h);
+    for c in &m.tool_calls {
+        (&c.id, c.args.len(), c.status as u8).hash(&mut h);
+    }
+    h.finish()
+}
+
+fn threads_sig(b: &Bot) -> u64 {
+    let mut h = std::collections::hash_map::DefaultHasher::new();
+    for (t, msgs) in &b.threads {
+        (t, msgs.len()).hash(&mut h);
+    }
+    h.finish()
+}
+
+fn hash_value(v: &Value) -> u64 {
+    let mut h = std::collections::hash_map::DefaultHasher::new();
+    v.to_string().hash(&mut h);
+    h.finish()
+}
+
+/// The person's edits since `base`, as operations the brain applies one by one.
+pub(super) fn diff_ops(base: &Value, cur: &Value) -> Vec<Value> {
+    let mut ops = vec![];
+    let (Some(b), Some(c)) = (base.as_object(), cur.as_object()) else { return ops };
+    for (k, v) in c {
+        if k == "bots" || LOCAL_KEYS.contains(&k.as_str()) {
+            continue;
+        }
+        if b.get(k) != Some(v) {
+            ops.push(json!({"op": "set", "key": k, "value": v}));
+        }
+    }
+    let id = |x: &Value| x["id"].as_u64().unwrap_or(0);
+    let empty = vec![];
+    let old = base["bots"].as_array().unwrap_or(&empty);
+    let new = cur["bots"].as_array().unwrap_or(&empty);
+    for nb in new {
+        match old.iter().find(|o| id(o) == id(nb)) {
+            None => ops.push(json!({"op": "bot_add", "bot": nb})),
+            Some(ob) => {
+                for (k, v) in nb.as_object().into_iter().flatten() {
+                    if k == "unread" {
+                        if ob[k] == true && *v == false {
+                            ops.push(json!({"op": "bot_read", "id": id(nb)}));
+                        }
+                        continue;
+                    }
+                    if BOT_RUNTIME.contains(&k.as_str()) {
+                        continue;
+                    }
+                    if ob.get(k) != Some(v) {
+                        ops.push(json!({"op": "bot_set", "id": id(nb), "key": k, "value": v}));
+                    }
+                }
+            }
+        }
+    }
+    for ob in old {
+        if !new.iter().any(|n| id(n) == id(ob)) {
+            ops.push(json!({"op": "bot_del", "id": id(ob)}));
+        }
+    }
+    let order = |a: &Vec<Value>| a.iter().map(id).collect::<Vec<_>>();
+    let (oo, no) = (order(old), order(new));
+    let kept: Vec<u64> = oo.iter().copied().filter(|i| no.contains(i)).collect();
+    let kept_new: Vec<u64> = no.iter().copied().filter(|i| oo.contains(i)).collect();
+    if kept != kept_new {
+        ops.push(json!({"op": "bot_order", "ids": no}));
+    }
+    ops
+}
+
+// ---------- the brain's side ----------
+
+/// What the brain last sent each screen.
+#[derive(Default)]
+pub struct Screens {
+    seen: HashMap<String, Seen>,
+    /// The settings fingerprint, refreshed now and then while something changes.
+    pub(super) cfg_hash: u64,
+    cfg_at: Option<Instant>,
+}
+
+#[derive(Default)]
+struct Seen {
+    version: u64,
+    config: u64,
+    bots: HashMap<u64, Vec<u64>>,
+    threads: HashMap<u64, u64>,
+    at: Option<Instant>,
+}
+
+// ---------- the screen's side ----------
+
+pub enum Incoming {
+    Pull(Value),
+    Offline(String),
+}
+
+#[derive(Default)]
+pub struct Mirror {
+    /// This window shows a brain (instead of its own bots).
+    pub on: bool,
+    /// Heard from the brain lately.
+    pub online: bool,
+    /// The brain's settings as last received (edits are what differs from this).
+    pub(super) base: Value,
+    pub status: Arc<Mutex<String>>,
+    rx: Option<Receiver<Incoming>>,
+    tx: Option<Sender<Incoming>>,
+    gen: Arc<AtomicU64>,
+    version: Arc<AtomicU64>,
+    client: String,
+    /// This computer's own data, kept aside while it shows the brain.
+    local: Option<State>,
+    started: bool,
+    /// A request to the brain failed (shown above the message box).
+    pub(super) error: Arc<Mutex<String>>,
+    /// The person chose a brain in 設定 (applied on the next frame).
+    pub(super) want: Option<(String, String)>,
+    pub(super) leave: bool,
+    pub(super) moving: Arc<AtomicBool>,
+    pub(super) move_note: Arc<Mutex<String>>,
+}
+
+fn cache_path() -> PathBuf {
+    State::path().with_file_name("brain-copy.json")
+}
+
+impl App {
+    /// The brain: answer the screens' requests (on the app's thread, where the state is).
+    pub(super) fn brain_serve(&mut self) {
+        let reqs = remote::hub().take_sync();
+        if reqs.is_empty() {
+            return;
+        }
+        for r in reqs {
+            let v = match r.kind {
+                SyncKind::Pull { client, since } => self.brain_pull(&client, since),
+                SyncKind::Edit(body) => {
+                    if self.mir.on {
+                        json!({"error": "這台 AnyBot 本身連著別的大腦"})
+                    } else {
+                        self.brain_edit(&body)
+                    }
+                }
+            };
+            let _ = r.reply.send(v);
+        }
+    }
+
+    /// Keep the settings fingerprint fresh (at most once a second) so screens hear of edits.
+    pub(super) fn brain_watch(&mut self) {
+        if self.mir.on || !self.dirty || self.scr.cfg_at.map(|t| t.elapsed().as_millis() < 1000).unwrap_or(false) {
+            return;
+        }
+        self.scr.cfg_at = Some(Instant::now());
+        let mut c = config_json(&mut self.state);
+        redact(&mut c);
+        self.scr.cfg_hash = hash_value(&c);
+    }
+
+    fn brain_pull(&mut self, client: &str, since: u64) -> Value {
+        if self.mir.on {
+            return json!({"error": "這台 AnyBot 本身連著別的大腦"});
+        }
+        let version = remote::hub().version();
+        // Forget screens not heard from in a day.
+        self.scr.seen.retain(|_, s| s.at.map(|t| t.elapsed().as_secs() < 86_400).unwrap_or(false));
+        let seen = self.scr.seen.entry(client.to_string()).or_default();
+        // A screen that missed an answer (or is new) gets everything again.
+        if seen.version != since || since == 0 {
+            *seen = Seen::default();
+        }
+        seen.at = Some(Instant::now());
+        seen.version = version;
+        let mut out = json!({"version": version, "brain": self.state.remote.host_name});
+        let mut c = config_json(&mut self.state);
+        redact(&mut c);
+        let ch = hash_value(&c);
+        if seen.config != ch {
+            seen.config = ch;
+            out["config"] = c;
+        }
+        let mut bots = vec![];
+        let mut threads = vec![];
+        for b in &self.state.bots {
+            let sigs: Vec<u64> = b.messages.iter().map(msg_sig).collect();
+            let old = seen.bots.get(&b.id);
+            let from = match old {
+                Some(o) => o.iter().zip(sigs.iter()).position(|(a, b)| a != b).unwrap_or(o.len().min(sigs.len())),
+                None => 0,
+            };
+            if old.map(|o| o.len() != sigs.len() || from < sigs.len()).unwrap_or(true) {
+                bots.push(json!({"id": b.id, "from": from, "messages": &b.messages[from..]}));
+            }
+            seen.bots.insert(b.id, sigs);
+            let ts = threads_sig(b);
+            if seen.threads.get(&b.id) != Some(&ts) {
+                seen.threads.insert(b.id, ts);
+                threads.push(json!({"id": b.id, "threads": b.threads}));
+            }
+        }
+        seen.bots.retain(|id, _| self.state.bots.iter().any(|b| b.id == *id));
+        out["bots"] = Value::Array(bots);
+        out["threads"] = Value::Array(threads);
+        out["live"] = self.streams.iter().map(|(id, l)| (id.to_string(), json!({"status": l.status, "paused": l.paused}))).collect::<serde_json::Map<_, _>>().into();
+        out["approvals"] = self
+            .approvals
+            .iter()
+            .map(|(id, a)| {
+                let kind = match a.kind {
+                    ApprovalKind::Action => "action",
+                    ApprovalKind::EnableTools => "tools",
+                    ApprovalKind::EnableThisComputer => "local",
+                };
+                json!({"bot": id, "call_id": a.call_id, "tool": a.tool, "reason": a.reason, "grant": a.grant, "kind": kind})
+            })
+            .collect();
+        out
+    }
+
+    /// A screen's edits.
+    pub(super) fn brain_edit(&mut self, body: &Value) -> Value {
+        let mut applied = 0;
+        for op in body["ops"].as_array().into_iter().flatten() {
+            let ok = match op["op"].as_str().unwrap_or("") {
+                "set" => self.brain_set_top(op["key"].as_str().unwrap_or(""), op["value"].clone()),
+                "bot_add" => {
+                    let mut v = op["bot"].clone();
+                    match serde_json::from_value::<Bot>(v.take()) {
+                        Ok(mut b) => {
+                            if b.id == 0 || self.state.bot(b.id).is_some() {
+                                b.id = self.state.next_id.max(1);
+                            }
+                            self.state.next_id = self.state.next_id.max(b.id + 1);
+                            self.state.bots.push(b);
+                            true
+                        }
+                        Err(_) => false,
+                    }
+                }
+                "bot_del" => {
+                    let id = op["id"].as_u64().unwrap_or(0);
+                    if id == self.state.primary_bot || self.state.bots.len() <= 1 {
+                        false
+                    } else {
+                        self.stop(id);
+                        self.state.bots.retain(|b| b.id != id);
+                        true
+                    }
+                }
+                "merge" => self.brain_merge_top(op["key"].as_str().unwrap_or(""), &op["value"]),
+                "bot_set" => self.brain_set_bot(op["id"].as_u64().unwrap_or(0), op["key"].as_str().unwrap_or(""), op["value"].clone()),
+                "bot_read" => match self.state.bot_mut(op["id"].as_u64().unwrap_or(0)) {
+                    Some(b) => {
+                        b.unread = false;
+                        true
+                    }
+                    None => false,
+                },
+                "bot_order" => {
+                    let ids: Vec<u64> = op["ids"].as_array().into_iter().flatten().filter_map(Value::as_u64).collect();
+                    self.state.bots.sort_by_key(|b| ids.iter().position(|i| *i == b.id).unwrap_or(usize::MAX));
+                    true
+                }
+                _ => false,
+            };
+            if ok {
+                applied += 1;
+            }
+        }
+        if applied > 0 {
+            self.mark();
+            // Screens hear of it at once.
+            self.scr.cfg_at = None;
+            self.brain_watch();
+        }
+        json!({"ok": true, "applied": applied})
+    }
+
+    fn brain_set_top(&mut self, key: &str, mut value: Value) -> bool {
+        if key.is_empty() || key == "bots" || LOCAL_KEYS.contains(&key) {
+            return false;
+        }
+        let bots = std::mem::take(&mut self.state.bots);
+        let mut top = serde_json::to_value(&self.state).unwrap_or(Value::Null);
+        unredact(&mut value, &top[key]);
+        // Counters never go back (a screen may be behind).
+        if key.starts_with("next_") {
+            value = json!(value.as_u64().unwrap_or(0).max(top[key].as_u64().unwrap_or(0)));
+        }
+        top[key] = value;
+        let ok = match serde_json::from_value::<State>(top) {
+            Ok(mut st) => {
+                st.remote = std::mem::take(&mut self.state.remote);
+                self.state = st;
+                true
+            }
+            Err(_) => false,
+        };
+        self.state.bots = bots;
+        ok
+    }
+
+    /// 搬到大腦: add what the brain doesn't have yet (keys it lacks, skills and connectors by name).
+    fn brain_merge_top(&mut self, key: &str, value: &Value) -> bool {
+        let bots = std::mem::take(&mut self.state.bots);
+        let top = serde_json::to_value(&self.state).unwrap_or(Value::Null);
+        self.state.bots = bots;
+        let mut cur = top[key].clone();
+        match (key, &mut cur) {
+            ("providers", Value::Object(o)) => {
+                for (k, v) in value.as_object().into_iter().flatten() {
+                    let missing = o.get(k).map(|x| x["api_key"].as_str().unwrap_or("").is_empty()).unwrap_or(true);
+                    if missing && v["api_key"].as_str().map(|s| !s.is_empty() && s != REDACTED).unwrap_or(false) {
+                        o.insert(k.clone(), v.clone());
+                    }
+                }
+            }
+            ("skills" | "mcp_servers", Value::Array(a)) => {
+                for v in value.as_array().into_iter().flatten() {
+                    if !a.iter().any(|x| x["name"] == v["name"]) {
+                        a.push(v.clone());
+                    }
+                }
+            }
+            _ => return false,
+        }
+        self.brain_set_top(key, cur)
+    }
+
+    fn brain_set_bot(&mut self, id: u64, key: &str, value: Value) -> bool {
+        if BOT_RUNTIME.contains(&key) {
+            return false;
+        }
+        let Some(i) = self.state.bots.iter().position(|b| b.id == id) else { return false };
+        let b = &mut self.state.bots[i];
+        let msgs = std::mem::take(&mut b.messages);
+        let threads = std::mem::take(&mut b.threads);
+        let mut v = serde_json::to_value(&*b).unwrap_or(Value::Null);
+        v[key] = value;
+        let ok = match serde_json::from_value::<Bot>(v) {
+            Ok(nb) => {
+                *b = nb;
+                true
+            }
+            Err(_) => false,
+        };
+        let b = &mut self.state.bots[i];
+        b.messages = msgs;
+        b.threads = threads;
+        ok
+    }
+
+    // ---------- the screen ----------
+
+    /// Once at start: a brain was chosen earlier, so show its copy.
+    pub(super) fn mirror_boot(&mut self) {
+        if self.mir.started || self.demo {
+            return;
+        }
+        self.mir.started = true;
+        self.mir.client = crate::httpd::random_hex(8);
+        if !self.state.remote.brain_id.is_empty() && !self.state.remote.host_token.is_empty() {
+            self.mirror_enter();
+        }
+    }
+
+    /// Start showing the brain: this computer's own bots are kept aside, untouched.
+    fn mirror_enter(&mut self) {
+        let ids: Vec<u64> = self.streams.keys().copied().collect();
+        for id in ids {
+            self.stop(id);
+        }
+        self.approvals.clear();
+        let local = self.state.clone();
+        if let Some(copy) = std::fs::read_to_string(cache_path()).ok().and_then(|s| serde_json::from_str::<State>(&s).ok()).filter(|s| !s.bots.is_empty()) {
+            self.state = copy;
+            self.keep_local_fields(&local);
+            // Edits wait for the brain's own answer; the copy may be old.
+        }
+        self.mir.base = Value::Null;
+        self.mir.local = Some(local);
+        self.mir.on = true;
+        self.mir.online = false;
+        self.mir.version.store(0, Ordering::SeqCst);
+        *self.mir.status.lock().unwrap() = "正在連到大腦…".into();
+        self.mirror_worker();
+    }
+
+    /// Back to this computer's own bots.
+    fn mirror_leave(&mut self) {
+        self.mir.gen.fetch_add(1, Ordering::SeqCst);
+        self.mir.on = false;
+        self.mir.online = false;
+        self.streams.clear();
+        self.approvals.clear();
+        if let Some(mut local) = self.mir.local.take() {
+            let mut remote = self.state.remote.clone();
+            remote.brain_id.clear();
+            remote.brain_name.clear();
+            local.remote = remote;
+            local.theme = self.state.theme;
+            local.accent = self.state.accent;
+            if local.bot(local.selected).is_none() {
+                local.selected = local.primary_bot;
+            }
+            self.state = local;
+        } else {
+            self.state.remote.brain_id.clear();
+            self.state.remote.brain_name.clear();
+        }
+        self.state.save();
+        self.dirty = false;
+    }
+
+    fn keep_local_fields(&mut self, from: &State) {
+        let st = &mut self.state;
+        st.remote = from.remote.clone();
+        st.theme = from.theme;
+        st.accent = from.accent;
+        st.sidebar_collapsed = from.sidebar_collapsed;
+        st.sidebar_width = from.sidebar_width;
+        st.machine_label = from.machine_label.clone();
+        st.local_execution = from.local_execution;
+        st.local_never = from.local_never;
+        st.messages_send = from.messages_send;
+        st.messages_no_ask = from.messages_no_ask;
+        if st.bot(from.selected).is_some() {
+            st.selected = from.selected;
+        } else if st.bot(st.selected).is_none() {
+            st.selected = st.primary_bot;
+        }
+    }
+
+    fn mirror_worker(&mut self) {
+        let gen = self.mir.gen.fetch_add(1, Ordering::SeqCst) + 1;
+        let (tx, rx) = channel();
+        self.mir.rx = Some(rx);
+        self.mir.tx = Some(tx.clone());
+        let (g, version, client, s) = (self.mir.gen.clone(), self.mir.version.clone(), self.mir.client.clone(), self.state.remote.clone());
+        let repaint = self.repaint_fn();
+        std::thread::spawn(move || {
+            let mut backoff = 1u64;
+            while g.load(Ordering::SeqCst) == gen {
+                match remote::sync_pull(&s, version.load(Ordering::SeqCst), &client) {
+                    Ok(v) => {
+                        backoff = 1;
+                        if g.load(Ordering::SeqCst) != gen {
+                            break;
+                        }
+                        version.store(v["version"].as_u64().unwrap_or(0), Ordering::SeqCst);
+                        let _ = tx.send(Incoming::Pull(v));
+                    }
+                    Err(e) => {
+                        let _ = tx.send(Incoming::Offline(e));
+                        // Start over (with everything) once it is back.
+                        version.store(0, Ordering::SeqCst);
+                        std::thread::sleep(std::time::Duration::from_secs(backoff));
+                        backoff = (backoff * 2).min(20);
+                    }
+                }
+                repaint();
+            }
+        });
+    }
+
+    fn repaint_fn(&self) -> Arc<dyn Fn() + Send + Sync> {
+        match &self.ctx_handle {
+            Some(c) => {
+                let c = c.clone();
+                Arc::new(move || c.request_repaint())
+            }
+            None => Arc::new(|| {}),
+        }
+    }
+
+    /// Every frame on a screen: take in what the brain sent.
+    pub(super) fn mirror_tick(&mut self) {
+        if let Some((id, name)) = self.mir.want.take() {
+            if self.mir.on {
+                self.mirror_leave();
+            }
+            self.state.remote.brain_id = id;
+            self.state.remote.brain_name = name;
+            self.state.save();
+            self.mirror_enter();
+        }
+        if std::mem::take(&mut self.mir.leave) && self.mir.on {
+            self.mirror_leave();
+        }
+        if !self.mir.on {
+            return;
+        }
+        let mut got = vec![];
+        if let Some(rx) = &self.mir.rx {
+            while let Ok(m) = rx.try_recv() {
+                got.push(m);
+            }
+        }
+        for m in got {
+            match m {
+                Incoming::Offline(e) => {
+                    self.mir.online = false;
+                    self.mir.base = Value::Null;
+                    *self.mir.status.lock().unwrap() = format!("連不到大腦「{}」：{e}。現在只能看，連上後會自動恢復。", self.state.remote.brain_name);
+                }
+                Incoming::Pull(v) => {
+                    if let Some(e) = v["error"].as_str() {
+                        self.mir.online = false;
+                        *self.mir.status.lock().unwrap() = e.to_string();
+                        continue;
+                    }
+                    self.mir.online = true;
+                    *self.mir.status.lock().unwrap() = format!("已連到大腦「{}」", v["brain"].as_str().unwrap_or(&self.state.remote.brain_name));
+                    self.mirror_apply(v);
+                }
+            }
+        }
+    }
+
+    fn mirror_apply(&mut self, v: Value) {
+        if v["config"].is_object() {
+            let cfg = v["config"].clone();
+            let local = std::mem::replace(&mut self.state, State::first_run());
+            match serde_json::from_value::<State>(cfg.clone()) {
+                Ok(mut st) => {
+                    // Chats stay as they are (they come separately).
+                    let mut old = local.bots.clone();
+                    for b in st.bots.iter_mut() {
+                        if let Some(o) = old.iter_mut().find(|o| o.id == b.id) {
+                            b.messages = std::mem::take(&mut o.messages);
+                            b.threads = std::mem::take(&mut o.threads);
+                        }
+                    }
+                    self.state = st;
+                    self.keep_local_fields(&local);
+                    self.mir.base = cfg;
+                }
+                Err(e) => {
+                    self.state = local;
+                    *self.mir.error.lock().unwrap() = format!("大腦的設定讀不出來（兩邊 AnyBot 版本不同？）：{e}");
+                }
+            }
+        }
+        for d in v["bots"].as_array().into_iter().flatten() {
+            let id = d["id"].as_u64().unwrap_or(0);
+            let from = d["from"].as_u64().unwrap_or(0) as usize;
+            let msgs: Vec<Message> = serde_json::from_value(d["messages"].clone()).unwrap_or_default();
+            if let Some(b) = self.state.bot_mut(id) {
+                b.messages.truncate(from);
+                b.messages.extend(msgs);
+            }
+        }
+        for d in v["threads"].as_array().into_iter().flatten() {
+            if let Some(b) = self.state.bot_mut(d["id"].as_u64().unwrap_or(0)) {
+                b.threads = serde_json::from_value(d["threads"].clone()).unwrap_or_default();
+            }
+        }
+        // Who is working, and what waits for the person.
+        let live: HashMap<u64, (Option<String>, bool)> = v["live"].as_object().into_iter().flatten().filter_map(|(k, l)| Some((k.parse().ok()?, (l["status"].as_str().map(String::from), l["paused"].as_bool().unwrap_or(false))))).collect();
+        self.streams.retain(|id, _| live.contains_key(id));
+        for (id, (status, paused)) in live {
+            let l = self.streams.entry(id).or_insert_with(|| Live {
+                cancel: Arc::new(AtomicBool::new(false)),
+                started: Instant::now(),
+                last: Instant::now(),
+                produced: true,
+                status: None,
+                paused: false,
+                steer: Arc::default(),
+                turn_id: String::new(),
+                direct: Arc::default(),
+            });
+            l.status = status;
+            l.paused = paused;
+            l.last = Instant::now();
+        }
+        let mut waiting = HashMap::new();
+        for a in v["approvals"].as_array().into_iter().flatten() {
+            let id = a["bot"].as_u64().unwrap_or(0);
+            let kind = match a["kind"].as_str().unwrap_or("") {
+                "tools" => ApprovalKind::EnableTools,
+                "local" => ApprovalKind::EnableThisComputer,
+                _ => ApprovalKind::Action,
+            };
+            let (reply, _) = channel();
+            let s = |k: &str| a[k].as_str().unwrap_or("").to_string();
+            waiting.insert(id, Approval { call_id: s("call_id"), tool: s("tool"), reason: s("reason"), grant: s("grant"), reply, kind });
+        }
+        let ctx = self.ctx_handle.clone();
+        for (id, a) in waiting {
+            let new = self.approvals.get(&id).map(|o| o.call_id != a.call_id).unwrap_or(true);
+            self.approvals.insert(id, a);
+            if new {
+                if let Some(c) = &ctx {
+                    self.on_new_approval(c, id);
+                }
+            }
+        }
+        let keep: Vec<u64> = v["approvals"].as_array().into_iter().flatten().filter_map(|a| a["bot"].as_u64()).collect();
+        self.approvals.retain(|id, _| keep.contains(id));
+        if self.state.bot(self.state.selected).is_none() {
+            self.state.selected = self.state.primary_bot;
+        }
+        self.mirror_save_copy();
+    }
+
+    fn mirror_save_copy(&mut self) {
+        if let Ok(s) = serde_json::to_string(&self.state) {
+            let p = cache_path();
+            let tmp = p.with_extension("tmp");
+            if std::fs::write(&tmp, s).is_ok() {
+                let _ = std::fs::rename(&tmp, &p);
+            }
+        }
+    }
+
+    /// Saving on a screen: edits go to the brain; this computer's own file keeps its own bots.
+    pub(super) fn mirror_save(&mut self) {
+        if let Some(local) = self.mir.local.as_mut() {
+            local.remote = self.state.remote.clone();
+            local.theme = self.state.theme;
+            local.accent = self.state.accent;
+            local.sidebar_collapsed = self.state.sidebar_collapsed;
+            local.sidebar_width = self.state.sidebar_width;
+            local.machine_label = self.state.machine_label.clone();
+            local.local_execution = self.state.local_execution;
+            local.local_never = self.state.local_never;
+            local.messages_send = self.state.messages_send;
+            local.messages_no_ask = self.state.messages_no_ask;
+            local.save();
+        }
+        if !self.mir.online || !self.mir.base.is_object() {
+            return;
+        }
+        let cur = config_json(&mut self.state);
+        let ops = diff_ops(&self.mir.base, &cur);
+        if ops.is_empty() {
+            return;
+        }
+        self.mir.base = cur;
+        let (s, err) = (self.state.remote.clone(), self.mir.error.clone());
+        std::thread::spawn(move || {
+            if let Err(e) = remote::sync_post(&s, "edit", &json!({"ops": ops})) {
+                *err.lock().unwrap() = format!("改動沒有存到大腦：{e}");
+            }
+        });
+    }
+
+    /// A chat action on a screen goes to the brain.
+    pub(super) fn mirror_act(&mut self, body: Value) {
+        if !self.mir.online {
+            *self.mir.error.lock().unwrap() = "連不到大腦，現在只能看。".into();
+            return;
+        }
+        let (s, err) = (self.state.remote.clone(), self.mir.error.clone());
+        std::thread::spawn(move || {
+            if let Err(e) = remote::sync_post(&s, "act", &body) {
+                *err.lock().unwrap() = format!("大腦沒有收到：{e}");
+            }
+        });
+    }
+
+    /// Send a message through the brain: files go up first, then the text.
+    pub(super) fn mirror_send(&mut self, bot: u64, text: String, atts: Vec<crate::attach::Attachment>) -> bool {
+        if !self.mir.online {
+            *self.mir.error.lock().unwrap() = "連不到大腦，訊息沒有送出。".into();
+            return false;
+        }
+        // Shown at once; the brain's copy replaces it.
+        if !self.streams.contains_key(&bot) {
+            if let Some(b) = self.state.bot_mut(bot) {
+                b.messages.push(Message { attachments: atts.clone(), ..Message::user(&text) });
+            }
+        }
+        let (s, err) = (self.state.remote.clone(), self.mir.error.clone());
+        std::thread::spawn(move || {
+            let mut paths = vec![];
+            for a in &atts {
+                match std::fs::read(&a.path).map_err(|e| e.to_string()).and_then(|b| remote::sync_upload(&s, bot, &a.name, &b)) {
+                    Ok(p) => paths.push(p),
+                    Err(e) => {
+                        *err.lock().unwrap() = format!("「{}」沒有傳到大腦：{e}", a.name);
+                    }
+                }
+            }
+            if let Err(e) = remote::sync_post(&s, "act", &json!({"bot": bot, "action": "send", "text": text, "attachments": paths})) {
+                *err.lock().unwrap() = format!("訊息沒有送到大腦：{e}");
+            }
+        });
+        true
+    }
+
+    /// 把這台的 Bot 搬到大腦: copy this computer's own bots (with their chats), keys, skills and
+    /// connectors to the brain, as new bots there.
+    pub(super) fn mirror_move_local(&mut self) {
+        let Some(local) = self.mir.local.clone() else { return };
+        if self.mir.moving.swap(true, Ordering::SeqCst) {
+            return;
+        }
+        let mut ops: Vec<Value> = vec![];
+        for b in &local.bots {
+            let mut v = serde_json::to_value(b).unwrap_or(Value::Null);
+            v["id"] = json!(0);
+            ops.push(json!({"op": "bot_add", "bot": v}));
+        }
+        let top = serde_json::to_value(&local).unwrap_or(Value::Null);
+        for k in ["providers", "skills", "mcp_servers"] {
+            ops.push(json!({"op": "merge", "key": k, "value": top[k]}));
+        }
+        let (s, note, busy, n) = (self.state.remote.clone(), self.mir.move_note.clone(), self.mir.moving.clone(), local.bots.len());
+        *note.lock().unwrap() = "搬移中…".into();
+        std::thread::spawn(move || {
+            *note.lock().unwrap() = match remote::sync_post(&s, "edit", &json!({"ops": ops})) {
+                Ok(v) => format!("已把 {n} 個 Bot 搬到大腦（{} 項）", v["applied"].as_u64().unwrap_or(0)),
+                Err(e) => format!("搬移失敗：{e}"),
+            };
+            busy.store(false, Ordering::SeqCst);
+        });
+    }
+
+    /// The bar above the chat while showing a brain.
+    pub(super) fn mirror_banner(&mut self, ui: &mut egui::Ui) {
+        if !self.mir.on {
+            return;
+        }
+        let p = self.pal;
+        let err = std::mem::take(&mut *self.mir.error.lock().unwrap());
+        if !err.is_empty() {
+            self.notice = Some(err);
+        }
+        if self.mir.online {
+            return;
+        }
+        let status = self.mir.status.lock().unwrap().clone();
+        ui.vertical_centered(|ui| {
+            ui.set_max_width(TRANSCRIPT_MAX_WIDTH.min(ui.available_width() - 48.0));
+            Frame::new().fill(p.danger.gamma_multiply(0.08)).corner_radius(8).inner_margin(Margin::symmetric(12, 8)).show(ui, |ui| {
+                ui.add(egui::Label::new(RichText::new(status).size(FONT_SM).color(p.text2)).wrap());
+            });
+        });
+        ui.add_space(6.0);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn edits_become_small_operations() {
+        let base = json!({"theme": "light", "folders": ["a"], "bots": [{"id": 1, "name": "A", "unread": true}, {"id": 2, "name": "B"}]});
+        let cur = json!({"theme": "dark", "folders": ["a", "b"], "bots": [{"id": 1, "name": "A2", "unread": false}, {"id": 3, "name": "C"}]});
+        let ops = diff_ops(&base, &cur);
+        // theme is this computer's own; folders changed.
+        assert!(ops.iter().any(|o| o["op"] == "set" && o["key"] == "folders"));
+        assert!(!ops.iter().any(|o| o["key"] == "theme"));
+        assert!(ops.iter().any(|o| o["op"] == "bot_set" && o["key"] == "name" && o["value"] == "A2"));
+        assert!(ops.iter().any(|o| o["op"] == "bot_read" && o["id"] == 1));
+        assert!(ops.iter().any(|o| o["op"] == "bot_add" && o["bot"]["id"] == 3));
+        assert!(ops.iter().any(|o| o["op"] == "bot_del" && o["id"] == 2));
+    }
+
+    #[test]
+    fn keys_stay_on_the_brain() {
+        let mut v = json!({"remote": {"host_token": "x"}, "providers": {"xai": {"api_key": "sk-1"}, "openai": {"api_key": ""}}, "channels": [{"id": 4, "token": "t"}]});
+        let old = v.clone();
+        redact(&mut v);
+        assert!(v.get("remote").is_none());
+        assert_eq!(v["providers"]["xai"]["api_key"], REDACTED);
+        assert_eq!(v["providers"]["openai"]["api_key"], "");
+        assert_eq!(v["channels"][0]["token"], REDACTED);
+        // An edit that kept the stand-in keeps the real key.
+        let mut edit = v["providers"].clone();
+        edit["openai"]["api_key"] = json!("sk-new");
+        unredact(&mut edit, &old["providers"]);
+        assert_eq!(edit["xai"]["api_key"], "sk-1");
+        assert_eq!(edit["openai"]["api_key"], "sk-new");
+        let mut ch = v["channels"].clone();
+        unredact(&mut ch, &old["channels"]);
+        assert_eq!(ch[0]["token"], "t");
+    }
+}

src/app/remote_ui.rs

@@ -51,9 +51,11 @@ impl App {
             return;
         }
         self.rm.started = true;
+        self.ctx_handle = Some(ctx.clone());
         let c = ctx.clone();
         remote::hub().set_repaint(Arc::new(move || c.request_repaint()));
         self.remote_apply_settings();
+        self.mirror_boot();
     }
 
     /// Hand changed settings to the server threads (and restart what depends on them).
@@ -84,8 +86,14 @@ impl App {
         }
         self.remote_apply_settings();
         for c in remote::hub().take_cmds() {
+            // A screen of another brain has no bots of its own to run phone requests on.
+            if self.mir.on && !matches!(c, Cmd::DeviceAdded(_) | Cmd::DeviceSeen(_)) {
+                continue;
+            }
             self.remote_cmd(ctx, c);
         }
+        self.brain_serve();
+        self.brain_watch();
         if let Some(rx) = &self.rm.join_rx {
             if let Ok(r) = rx.try_recv() {
                 self.rm.join_rx = None;
@@ -118,7 +126,7 @@ impl App {
         }
         // 自動備份: once a day while signed in.
         let s = &self.state.remote;
-        if s.auto_backup && !s.backup_key.is_empty() && !s.relay_url.is_empty() && chrono::Utc::now().timestamp() - s.last_backup > 86_400 && !self.rm.busy.load(Ordering::SeqCst) {
+        if !self.mir.on && s.auto_backup && !s.backup_key.is_empty() && !s.relay_url.is_empty() && chrono::Utc::now().timestamp() - s.last_backup > 86_400 && !self.rm.busy.load(Ordering::SeqCst) {
             self.remote_backup();
         }
         // 裝置連結: keep the list of this account's computers fresh (once a minute).
@@ -132,7 +140,7 @@ impl App {
                 }
             });
         }
-        if !self.rm.last_publish.map(|t| t.elapsed().as_millis() < 120).unwrap_or(false) {
+        if !self.mir.on && !self.rm.last_publish.map(|t| t.elapsed().as_millis() < 120).unwrap_or(false) {
             self.remote_publish();
         }
     }
@@ -140,6 +148,7 @@ impl App {
     fn remote_signature(&self) -> u64 {
         let mut h = std::collections::hash_map::DefaultHasher::new();
         self.state.remote.host_name.hash(&mut h);
+        self.scr.cfg_hash.hash(&mut h);
         for b in &self.state.bots {
             (b.id, &b.name, &b.color, b.unread, b.messages.len()).hash(&mut h);
             if let Some(m) = b.messages.last() {
@@ -214,6 +223,27 @@ impl App {
                 self.start_reply(ctx, bot);
             }
             Cmd::Stop { bot } => self.stop(bot),
+            Cmd::Regenerate { bot } => self.regenerate(ctx, bot),
+            Cmd::Reply { bot } => {
+                if !self.streams.contains_key(&bot) && self.state.bot(bot).and_then(|b| b.messages.last()).map(|m| m.role == Role::User).unwrap_or(false) {
+                    self.start_reply(ctx, bot);
+                }
+            }
+            Cmd::RestoreThread { bot, index } => {
+                self.stop(bot);
+                if let Some(b) = self.state.bot_mut(bot) {
+                    if index < b.threads.len() {
+                        let (_, msgs) = b.threads.remove(index);
+                        if !b.messages.is_empty() {
+                            let title = b.messages.iter().find(|m| m.role == Role::User).map(|m| first_line(&m.text, 24)).unwrap_or_else(|| "對話".into());
+                            let cur = std::mem::take(&mut b.messages);
+                            b.threads.insert(0, (title, cur));
+                        }
+                        b.messages = msgs;
+                    }
+                }
+                self.mark();
+            }
             Cmd::Answer { bot, answer } => {
                 let grant = self.approvals.get(&bot).map(|a| a.grant.clone()).unwrap_or_default();
                 let a = match answer.as_str() {
@@ -380,6 +410,60 @@ impl App {
             }
         });
 
+        // ── 大腦 ──
+        if !self.state.remote.host_token.is_empty() {
+            setting_card(ui, p, |ui| {
+                ui.horizontal(|ui| {
+                    ui.label(RichText::new(t("大腦")).size(FONT_BASE).strong());
+                    help_mark(ui, "帳號裡選一台 AnyBot 當大腦（通常是跟帳號伺服器放在一起、一直開著的那台）。所有 Bot、聊天、記憶和例行任務都放在大腦上，由它思考和排程。其他電腦打開 AnyBot 看到的都是同一份，同時也是大腦的手腳：大腦的 Bot 可以透過裝置連結操作它們。大腦連不到時，這裡還能看之前的對話，但不能傳訊息，連回來就恢復。", p);
+                });
+                let s = &self.state.remote;
+                let status = self.mir.status.lock().unwrap().clone();
+                if self.mir.on {
+                    ui.horizontal(|ui| {
+                        let (r, _) = ui.allocate_exact_size(vec2(10.0, 10.0), egui::Sense::hover());
+                        ui.painter().circle_filled(r.center(), 4.0, if self.mir.online { Color32::from_rgb(0x14, 0xc3, 0x70) } else { p.text3 });
+                        ui.label(RichText::new(status).size(13.0).color(p.text2));
+                    });
+                    ui.horizontal(|ui| {
+                        let busy = self.mir.moving.load(Ordering::SeqCst);
+                        if ui.add_enabled(self.mir.online && !busy, secondary_button("把這台的 Bot 搬過去")).on_hover_text(t("把這台電腦原本的 Bot（連同聊天）、模型金鑰、技能和連接器複製到大腦。這台的原始資料不會刪掉。")).clicked() {
+                            self.mirror_move_local();
+                        }
+                        if ui.add(secondary_button("改回用這台自己的 Bot")).clicked() {
+                            self.mir.leave = true;
+                        }
+                    });
+                    let note = self.mir.move_note.lock().unwrap().clone();
+                    if !note.is_empty() {
+                        ui.label(RichText::new(note).size(12.5).color(p.text2));
+                    }
+                } else {
+                    ui.label(RichText::new(t("這台就是大腦：Bot 在這台電腦上思考和工作。")).size(13.0).color(p.text2));
+                    let me = s.host_id.clone();
+                    let peers: Vec<(String, String, bool)> = self.rm.peers.lock().unwrap().iter().filter(|(id, _, _)| !id.is_empty() && *id != me).cloned().collect();
+                    if peers.is_empty() {
+                        hint(ui, "帳號裡還沒有其他 AnyBot。在伺服器上啟動 anybot --serve 並登入同一個帳號，它就會出現在這裡。", p);
+                    }
+                    for (id, name, online) in peers {
+                        ui.horizontal(|ui| {
+                            let (r, _) = ui.allocate_exact_size(vec2(10.0, 10.0), egui::Sense::hover());
+                            ui.painter().circle_filled(r.center(), 4.0, if online { Color32::from_rgb(0x14, 0xc3, 0x70) } else { p.text3 });
+                            ui.label(RichText::new(&name).size(13.5));
+                            ui.with_layout(Layout::right_to_left(Align::Center), |ui| {
+                                if ui.add_enabled(online, secondary_button("改用它當大腦")).clicked() {
+                                    self.mir.want = Some((id.clone(), name.clone()));
+                                    // The brain's bots may use this computer (each action still asks).
+                                    self.state.remote.device_link = true;
+                                    changed = true;
+                                }
+                            });
+                        });
+                    }
+                }
+            });
+        }
+
         // ── 同一個網路 ──
         setting_card(ui, p, |ui| {
             setting_title(ui, "同一個網路直接連", "手機和這台電腦在同一個 Wi-Fi，或都裝了 Tailscale 時使用。", p);

src/remote.rs

@@ -72,11 +72,17 @@ pub struct Settings {
     pub auto_backup: bool,
     #[serde(default)]
     pub last_backup: i64,
+    /// 大腦: the AnyBot of this account whose bots, chats and settings this one shows (its relay
+    /// host id). Empty = this AnyBot is its own brain. When set, this one is a screen and hands.
+    #[serde(default, skip_serializing_if = "String::is_empty")]
+    pub brain_id: String,
+    #[serde(default, skip_serializing_if = "String::is_empty")]
+    pub brain_name: String,
 }
 
 impl Default for Settings {
     fn default() -> Self {
-        Settings { lan: false, password: String::new(), devices: vec![], mac_from_phone: false, device_link: false, relay_url: String::new(), relay_user: String::new(), host_id: String::new(), host_token: String::new(), host_name: default_host_name(), backup_key: String::new(), auto_backup: true, last_backup: 0 }
+        Settings { lan: false, password: String::new(), devices: vec![], mac_from_phone: false, device_link: false, relay_url: String::new(), relay_user: String::new(), host_id: String::new(), host_token: String::new(), host_name: default_host_name(), backup_key: String::new(), auto_backup: true, last_backup: 0, brain_id: String::new(), brain_name: String::new() }
     }
 }
 
@@ -103,6 +109,11 @@ pub enum Cmd {
     Answer { bot: u64, answer: String },
     Read { bot: u64 },
     NewThread { bot: u64 },
+    /// Answer the last message again (重新產生) / reply to what is there (重新傳送).
+    Regenerate { bot: u64 },
+    Reply { bot: u64 },
+    /// Bring back an earlier conversation (過去的對話).
+    RestoreThread { bot: u64, index: usize },
     /// A new phone signed in (to remember), or one was signed out.
     DeviceAdded(Device),
     DeviceSeen(String),
@@ -126,11 +137,23 @@ pub struct Hub {
     settings: Mutex<Settings>,
     fails: Mutex<(u32, Option<Instant>)>,
     relay_status: Mutex<String>,
+    sync: Mutex<Vec<SyncReq>>,
+}
+
+/// 大腦: another AnyBot of this account (a screen) asks for what changed, or sends its edits.
+pub enum SyncKind {
+    Pull { client: String, since: u64 },
+    Edit(Value),
+}
+
+pub struct SyncReq {
+    pub kind: SyncKind,
+    pub reply: std::sync::mpsc::Sender<Value>,
 }
 
 pub fn hub() -> &'static Hub {
     static H: OnceLock<Hub> = OnceLock::new();
-    H.get_or_init(|| Hub { view: Mutex::new(View::default()), changed: Condvar::new(), cmds: Mutex::new(vec![]), repaint: Mutex::new(None), settings: Mutex::new(Settings::default()), fails: Mutex::new((0, None)), relay_status: Mutex::new(String::new()) })
+    H.get_or_init(|| Hub { view: Mutex::new(View::default()), changed: Condvar::new(), cmds: Mutex::new(vec![]), repaint: Mutex::new(None), settings: Mutex::new(Settings::default()), fails: Mutex::new((0, None)), relay_status: Mutex::new(String::new()), sync: Mutex::new(vec![]) })
 }
 
 static VERSION: AtomicU64 = AtomicU64::new(1);
@@ -141,6 +164,21 @@ impl Hub {
         *self.view.lock().unwrap() = v;
         self.changed.notify_all();
     }
+    pub fn take_sync(&self) -> Vec<SyncReq> {
+        std::mem::take(&mut *self.sync.lock().unwrap())
+    }
+    /// Hand a sync request to the app's thread and wait for its answer.
+    fn ask_sync(&self, kind: SyncKind) -> Result<Value, String> {
+        let (tx, rx) = std::sync::mpsc::channel();
+        self.sync.lock().unwrap().push(SyncReq { kind, reply: tx });
+        if let Some(r) = self.repaint.lock().unwrap().as_ref() {
+            r();
+        }
+        rx.recv_timeout(Duration::from_secs(10)).map_err(|_| "大腦沒有及時回應".to_string())
+    }
+    pub fn version(&self) -> u64 {
+        self.view.lock().unwrap().version
+    }
     pub fn take_cmds(&self) -> Vec<Cmd> {
         std::mem::take(&mut *self.cmds.lock().unwrap())
     }
@@ -328,6 +366,44 @@ pub fn handle(req: Req, via_relay: bool) -> Resp {
         ("GET", ["api", "screen", which]) => screen(which, &s),
         ("POST", ["api", "screen", which]) => screen_input(which, &req.json(), &s),
         ("POST", ["api", "device", "run"]) => device_run(&req.json(), &s, via_relay),
+        ("GET", ["api", "sync"]) => {
+            let since: u64 = req.query.get("since").and_then(|v| v.parse().ok()).unwrap_or(0);
+            let client = req.query.get("client").cloned().unwrap_or_default();
+            if since > 0 {
+                let _ = hub().wait_newer(since, LONG_POLL_SECS);
+            }
+            match hub().ask_sync(SyncKind::Pull { client, since }) {
+                Ok(v) => Resp::json(&v),
+                Err(e) => Resp::error(503, &e),
+            }
+        }
+        ("POST", ["api", "sync", "edit"]) => match hub().ask_sync(SyncKind::Edit(req.json())) {
+            Ok(v) if v["error"].is_string() => Resp::error(400, v["error"].as_str().unwrap_or("")),
+            Ok(v) => Resp::json(&v),
+            Err(e) => Resp::error(503, &e),
+        },
+        ("POST", ["api", "sync", "upload", id]) => upload(id.parse().unwrap_or(0), &req),
+        ("POST", ["api", "sync", "act"]) => {
+            let b = req.json();
+            let bot = b["bot"].as_u64().unwrap_or(0);
+            let cmd = match b["action"].as_str().unwrap_or("") {
+                "send" => Cmd::Send {
+                    bot,
+                    text: b["text"].as_str().unwrap_or("").trim().to_string(),
+                    attachments: b["attachments"].as_array().map(|a| a.iter().filter_map(|x| x.as_str().map(String::from)).collect()).unwrap_or_default(),
+                },
+                "stop" => Cmd::Stop { bot },
+                "answer" => Cmd::Answer { bot, answer: b["answer"].as_str().unwrap_or("reject").to_string() },
+                "read" => Cmd::Read { bot },
+                "new" => Cmd::NewThread { bot },
+                "regenerate" => Cmd::Regenerate { bot },
+                "reply" => Cmd::Reply { bot },
+                "restore" => Cmd::RestoreThread { bot, index: b["index"].as_u64().unwrap_or(0) as usize },
+                _ => return Resp::error(404, "沒有這個動作"),
+            };
+            hub().push(cmd);
+            Resp::json(&json!({"ok": true}))
+        }
         ("POST", ["api", "logout"]) if !via_relay => {
             let h = httpd::sha256_hex(&req.bearer());
             hub().push(Cmd::DeviceSeen(format!("-{h}")));
@@ -342,9 +418,12 @@ pub fn handle(req: Req, via_relay: bool) -> Resp {
 /// account) may run tools here.
 pub fn role_allows(role: &str, method: &str, path: &[&str]) -> bool {
     let device = matches!(path, ["api", "device", "run"]);
+    let sync = matches!(path, ["api", "sync", ..]);
     match role {
         "device" => device,
-        "owner" | "admin" => !device,
+        // 大腦: the owner's other AnyBots showing this one's bots.
+        "mirror" => sync,
+        "owner" | "admin" => !device && !sync,
         "member" => matches!((method, path), ("GET", ["api", "state"]) | ("GET", ["api", "bots", _]) | ("POST", ["api", "bots", _, "send" | "read" | "upload"])),
         _ => false,
     }
@@ -484,6 +563,15 @@ fn device_run(v: &Value, s: &Settings, via_relay: bool) -> Resp {
         let (text, ok, img) = crate::computer::run_by(tool, args, who);
         return Resp::json(&json!({"text": text, "ok": ok, "image": img}));
     }
+    // The AnyBot browser here (its logins are this computer's).
+    if crate::web::is_web_tool(tool) && tool != "web_fetch" {
+        let mut v: Value = serde_json::from_str(args).unwrap_or(json!({}));
+        if let Some(o) = v.as_object_mut() {
+            o.remove("computer");
+        }
+        let (text, ok, img) = crate::web::run_full(tool, &v.to_string(), &std::sync::atomic::AtomicBool::new(false));
+        return Resp::json(&json!({"text": text, "ok": ok, "image": img}));
+    }
     if crate::macapps::is_mac_tool(tool) && cfg!(target_os = "macos") {
         let (text, ok) = crate::macapps::run(tool, args);
         return Resp::json(&json!({"text": text, "ok": ok}));
@@ -753,6 +841,58 @@ pub fn run_on_device(host_id: &str, tool: &str, args: &str, who: &str) -> Result
     Ok(v)
 }
 
+// ---------- 大腦: this AnyBot as a screen of another ----------
+
+fn brain_url(s: &Settings, rest: &str) -> Result<String, String> {
+    if s.relay_url.is_empty() || s.host_token.is_empty() {
+        return Err("沒有登入帳號".into());
+    }
+    if s.brain_id.is_empty() {
+        return Err("沒有選大腦".into());
+    }
+    Ok(format!("{}/relay/hosts/{}/api/sync{rest}", s.relay_url, s.brain_id))
+}
+
+fn read_reply(r: Result<ureq::http::Response<ureq::Body>, ureq::Error>) -> Result<Value, String> {
+    let mut resp = r.map_err(|e| format!("連不到帳號伺服器：{e}"))?;
+    let st = resp.status().as_u16();
+    let text = resp.body_mut().with_config().limit(200 * 1024 * 1024).read_to_string().unwrap_or_default();
+    let v: Value = serde_json::from_str(&text).unwrap_or(Value::Null);
+    if !(200..300).contains(&st) {
+        return Err(v["error"].as_str().map(String::from).unwrap_or(format!("大腦沒有回應（HTTP {st}）")));
+    }
+    Ok(v)
+}
+
+/// What changed at the brain since `since` (waits up to LONG_POLL_SECS when nothing has).
+pub fn sync_pull(s: &Settings, since: u64, client: &str) -> Result<Value, String> {
+    let url = brain_url(s, &format!("?since={since}&client={client}"))?;
+    read_reply(agent(LONG_POLL_SECS + 25).get(&url).header("Authorization", &format!("Bearer {}", s.host_token)).call())
+}
+
+/// Send edits ("edit") or a chat action ("act") to the brain.
+pub fn sync_post(s: &Settings, what: &str, body: &Value) -> Result<Value, String> {
+    let url = brain_url(s, &format!("/{what}"))?;
+    read_reply(agent(60).post(&url).header("Authorization", &format!("Bearer {}", s.host_token)).header("Content-Type", "application/json").send(body.to_string().as_bytes()))
+}
+
+/// A file for the next message, kept at the brain; gives back its path there.
+pub fn sync_upload(s: &Settings, bot: u64, name: &str, bytes: &[u8]) -> Result<String, String> {
+    let q: String = url_escape(name);
+    let url = brain_url(s, &format!("/upload/{bot}?name={q}"))?;
+    let v = read_reply(agent(120).post(&url).header("Authorization", &format!("Bearer {}", s.host_token)).header("Content-Type", "application/octet-stream").send(bytes))?;
+    v["path"].as_str().map(String::from).ok_or("大腦沒有收下檔案".into())
+}
+
+fn url_escape(s: &str) -> String {
+    s.bytes()
+        .map(|b| match b {
+            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' => (b as char).to_string(),
+            _ => format!("%{b:02X}"),
+        })
+        .collect()
+}
+
 /// A notification on the person's phones (through the relay; phones that turned them on).
 pub fn notify(title: &str, body: &str, bot: u64) {
     let s = hub().settings();

src/web.rs

@@ -59,7 +59,28 @@ pub fn read_needs_permission(args: &str) -> bool {
     uses_person_browser(args)
 }
 
-pub fn specs() -> Vec<Value> {
+/// The browser tools, also when the browser is on another computer of the account (裝置連結):
+/// then each takes a `computer`, since each computer's AnyBot browser has its own logins.
+pub fn specs_for(devices: &[String]) -> Vec<Value> {
+    let local = crate::botbrowser::available();
+    let mut v = specs_inner(local || !devices.is_empty());
+    if !devices.is_empty() {
+        let mut names: Vec<String> = devices.to_vec();
+        if local {
+            names.insert(0, crate::model::THIS_COMPUTER_NAME.to_string());
+        }
+        let desc = format!(
+            "Which computer's AnyBot browser to use. Each computer's browser has its own logins (a site logged in on one isn't on another). {}",
+            if local { format!("Leave out for {}.", crate::model::THIS_COMPUTER_NAME) } else { "This computer has no browser: always name one.".to_string() }
+        );
+        for t in v.iter_mut().filter(|t| t["name"].as_str().map(|n| n.starts_with("browser_")).unwrap_or(false)) {
+            t["parameters"]["properties"]["computer"] = json!({"type": "string", "enum": names, "description": desc});
+        }
+    }
+    v
+}
+
+fn specs_inner(browser: bool) -> Vec<Value> {
     let (names, current) = if crate::botbrowser::available() {
         (crate::botbrowser::choices().join(", "), crate::botbrowser::current())
     } else {
@@ -76,7 +97,7 @@ pub fn specs() -> Vec<Value> {
         json!({"name": "browser_profiles", "description": "List, add or switch AnyBot browser profiles (設定檔/profile). Use when the person wants another profile or account: 'list' shows them, 'add' makes a new empty one (they log in once there) and switches to it, 'use' switches. Switching changes which profile browser_open/browser_read use.",
             "parameters": {"type": "object", "properties": {"action": {"type": "string", "enum": ["list", "add", "use"]}, "name": {"type": "string", "description": "Profile name for add/use."}}, "required": ["action"]}}),
     ];
-    if crate::botbrowser::available() {
+    if browser {
         v.extend(crate::browser::specs(&profile));
     }
     v