feat(adopt): read a pre-existing tab without opening a new one

New `chrome-use adopt <url-substring|targetId>`: drive a tab the user (or
another session) already has open, with ZERO new tabs. After group-scoped
isolation (#40) a session can't see foreign tabs, so adopt adds an explicit,
opt-in path:

- Relay (relay.rs): `ABRelay.getAllTargets` returns every attached target
  UNSCOPED (ignores group scoping), so the agent can find a specific tab by URL
  or targetId. +1 unit test.
- Daemon (browser.rs): `collect_all_targets` (unscoped, falls back to scoped on
  older relays) + `adopt_existing_target` — matches by exact targetId or
  case-insensitive URL substring, attaches it (the relay re-tags it into the
  adopter's group, so isolation holds), pins it; never creates a tab. On no
  match it errors AND lists the open tabs it can see, rather than launching.
  discover_and_attach_targets honors AGENT_BROWSER_ADOPT at first connect, so no
  about:blank is ever created.
- CLI (main.rs): `adopt` sets the env, forces a fresh daemon, and rewrites into
  `connect <relay-url>` (like `extension connect`) so the daemon attaches to the
  user's real Chrome before parse_command.

Extension (ab-connect 0.4.11): `reannounceAttachedTabs` now re-sends each tab's
url/title (it previously sent neither) so the relay's target list stays matchable
by URL after the MV3 service worker reconnects — otherwise reannounced tabs show
a blank url and `adopt <url>` can't find them. Repacked upload zip + crx.

Mechanism verified live (enumerated all 11 of the user's open tabs incl. the
target). 862 tests pass.

cli/Cargo.lock

@@ -290,7 +290,7 @@ checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
 
 [[package]]
 name = "chrome-use"
-version = "1.5.21"
+version = "1.5.23"
 dependencies = [
  "aes",
  "aes-gcm",

cli/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "chrome-use"
-version = "1.5.21"
+version = "1.5.23"
 edition = "2021"
 description = "Fast browser automation CLI for AI agents"
 license = "Apache-2.0"

cli/src/commands.rs

@@ -80,6 +80,7 @@ const KNOWN_COMMANDS: &[&str] = &[
     "upload",
     "site",
     "box",
+    "adopt",
 ];
 
 /// Levenshtein distance, capped — small inputs only (command names).
@@ -1317,6 +1318,12 @@ fn parse_command_inner(args: &[String], flags: &Flags) -> Result<Value, ParseErr
             Ok(json!({ "id": id, "action": "site", "domain": domain, "script": script }))
         }
 
+        // `adopt <url|targetId>`: the adoption happens at daemon connect (driven by
+        // the AGENT_BROWSER_ADOPT env main.rs set + a forced-fresh daemon), so by
+        // the time this command runs the tab is already attached. Resolve to a
+        // `url` read so the response confirms which tab got adopted.
+        "adopt" => Ok(json!({ "id": id, "action": "url" })),
+
         // === Stealth self-check ===
         "stealth" => {
             // `stealth [status]` — local stealth self-check: mode, live probes

cli/src/connection.rs

@@ -595,7 +595,7 @@ fn query_current_url(session: &str) -> Option<String> {
 }
 
 /// Kill a running daemon by reading its PID file and sending a kill signal.
-fn kill_stale_daemon(session: &str) {
+pub fn kill_stale_daemon(session: &str) {
     // Remove the socket first so no new connections reach the old daemon
     #[cfg(unix)]
     {

cli/src/main.rs

@@ -981,6 +981,43 @@ fn main() {
         }
     }
 
+    // `adopt <url|targetId>`: read a PRE-EXISTING tab (the user's own, or another
+    // session's) WITHOUT opening a new one. Forces a fresh daemon and points it at
+    // the relay (like `extension connect`); the AGENT_BROWSER_ADOPT env makes the
+    // daemon's first connect ADOPT the matching tab instead of creating an
+    // about:blank. Rewrites into `connect <relay-url>` BEFORE parse_command so the
+    // daemon attaches to the user's real Chrome. Must run before parse_command.
+    if clean.first().map(|s| s.as_str()) == Some("adopt") {
+        match clean.get(1) {
+            Some(spec) if !spec.trim().is_empty() => {
+                std::env::set_var("AGENT_BROWSER_ADOPT", spec.trim());
+                connection::kill_stale_daemon(&flags.session);
+                match connect::relay_url() {
+                    Some(url) => {
+                        flags.cdp = Some(url.clone());
+                        flags.auto_connect = false;
+                        clean = vec!["connect".to_string(), url];
+                    }
+                    None => {
+                        eprintln!(
+                            "{} extension relay not connected — open Chrome with the ab-connect \
+                             extension first (this command reads an EXISTING tab, it won't launch one).",
+                            color::error_indicator()
+                        );
+                        exit(1);
+                    }
+                }
+            }
+            _ => {
+                eprintln!(
+                    "{} usage: chrome-use adopt <url-substring|targetId>  (reads an existing tab, no new tab)",
+                    color::error_indicator()
+                );
+                exit(2);
+            }
+        }
+    }
+
     // Handle session separately (doesn't need daemon)
     if clean.first().map(|s| s.as_str()) == Some("session") {
         run_session(&clean, &flags.session, flags.json);

cli/src/native/browser.rs

@@ -509,6 +509,13 @@ pub struct BrowserManager {
     /// for `RELAY_PRUNE_MISSES` consecutive snapshots; any snapshot that includes
     /// it resets the counter. Keyed by stable target_id.
     relay_target_misses: HashMap<String, u32>,
+    /// Whether the relay accepted this session's group announcement and is
+    /// therefore scoping `Target.getTargets` to our own tab group (issue #40).
+    /// When true the daemon can safely adopt new targets again (follow-popup,
+    /// cross-session adopt) — the relay has already filtered out foreign tabs.
+    /// When false (launch-on-real-CDP, or an older relay that didn't answer the
+    /// announce) the daemon keeps strict daemon-side isolation.
+    relay_scoped: bool,
     next_tab_id: u32,
     /// Whether to enable the CDP `Runtime` domain (console / error / exception capture).
     /// OFF by default for stealth: a live `Runtime.enable` is a detectable CDP signal
@@ -646,6 +653,7 @@ impl BrowserManager {
                 created_targets: HashSet::new(),
                 active_target_id: None,
                 relay_target_misses: HashMap::new(),
+                relay_scoped: false,
                 next_tab_id: 1,
                 capture_console: console_capture_enabled(),
             };
@@ -749,6 +757,7 @@ impl BrowserManager {
             created_targets: HashSet::new(),
             active_target_id: None,
             relay_target_misses: HashMap::new(),
+            relay_scoped: false,
             next_tab_id: 1,
             capture_console: console_capture_enabled(),
         };
@@ -815,6 +824,106 @@ impl BrowserManager {
         Ok(by_id.into_values().collect())
     }
 
+    /// Every tab the relay knows, UNSCOPED (ignores group scoping) — for explicit
+    /// cross-group adoption (`chrome-use adopt`). Falls back to the scoped
+    /// `collect_page_targets` on a relay/browser that doesn't support the
+    /// unscoped query. Retries a few times over the relay (discovery is eventual).
+    async fn collect_all_targets(&self) -> Result<Vec<TargetInfo>, String> {
+        let rounds = if crate::connect::relay_url().is_some() {
+            3
+        } else {
+            1
+        };
+        let mut by_id: HashMap<String, TargetInfo> = HashMap::new();
+        let mut any_ok = false;
+        for i in 0..rounds {
+            if i > 0 {
+                tokio::time::sleep(Duration::from_millis(150)).await;
+            }
+            if let Ok(result) = self
+                .client
+                .send_command_typed::<_, GetTargetsResult>(
+                    "ABRelay.getAllTargets",
+                    &json!({}),
+                    None,
+                )
+                .await
+            {
+                any_ok = true;
+                for t in result.target_infos.into_iter().filter(should_track_target) {
+                    by_id.entry(t.target_id.clone()).or_insert(t);
+                }
+            }
+        }
+        if any_ok {
+            Ok(by_id.into_values().collect())
+        } else {
+            // Older relay without ABRelay.getAllTargets → best-effort scoped list.
+            self.collect_page_targets().await
+        }
+    }
+
+    /// Adopt a specific pre-existing tab matched by `spec` (an exact CDP
+    /// `targetId`, or a case-insensitive substring of the tab URL) WITHOUT opening
+    /// a new tab — for `chrome-use adopt`. Attaches it (the relay tags it into our
+    /// group), tracks + pins it. Errors if nothing matches (never creates a tab).
+    async fn adopt_existing_target(&mut self, spec: &str) -> Result<(), String> {
+        let all = self.collect_all_targets().await?;
+        let spec_l = spec.to_lowercase();
+        let target = all
+            .iter()
+            .find(|t| t.target_id == spec)
+            .or_else(|| all.iter().find(|t| t.url.to_lowercase().contains(&spec_l)))
+            .ok_or_else(|| {
+                let mut open: Vec<String> = all
+                    .iter()
+                    .map(|t| {
+                        let u = if t.url.len() > 80 {
+                            &t.url[..80]
+                        } else {
+                            &t.url
+                        };
+                        u.to_string()
+                    })
+                    .collect();
+                open.sort();
+                open.dedup();
+                format!(
+                    "adopt: no open tab matching `{spec}` (by targetId or URL substring).\n\
+                     {} tab(s) the extension can see:\n  {}",
+                    open.len(),
+                    open.join("\n  ")
+                )
+            })?
+            .clone();
+
+        let attach: AttachToTargetResult = self
+            .client
+            .send_command_typed(
+                "Target.attachToTarget",
+                &AttachToTargetParams {
+                    target_id: target.target_id.clone(),
+                    flatten: true,
+                },
+                None,
+            )
+            .await?;
+        let tab_id = self.assign_tab_id();
+        self.pages.push(PageInfo {
+            tab_id,
+            label: None,
+            target_id: target.target_id.clone(),
+            session_id: attach.session_id.clone(),
+            url: target.url.clone(),
+            title: sanitize_title(&target.title),
+            target_type: target.target_type.clone(),
+        });
+        self.active_page_index = self.pages.len() - 1;
+        self.pin_active_target();
+        self.enable_domains(&attach.session_id).await?;
+        Ok(())
+    }
+
     async fn discover_and_attach_targets(&mut self) -> Result<(), String> {
         self.client
             .send_command_typed::<_, Value>(
@@ -824,6 +933,21 @@ impl BrowserManager {
             )
             .await?;
 
+        // Announce our group FIRST so the relay scopes the getTargets below to our
+        // own tab group (issue #40). On a launched browser this is a no-op.
+        let scoped = self.announce_group().await;
+
+        // `chrome-use adopt <spec>`: adopt a specific PRE-EXISTING tab instead of
+        // creating one — true zero-new-tab reading of the user's own tab. The
+        // directive rides in via env so it takes effect at first connect (before
+        // any about:blank would be made). If nothing matches, error out rather
+        // than fall back to creating a tab.
+        if let Ok(spec) = std::env::var("AGENT_BROWSER_ADOPT") {
+            if !spec.trim().is_empty() {
+                return self.adopt_existing_target(spec.trim()).await;
+            }
+        }
+
         let page_targets: Vec<TargetInfo> = self.collect_page_targets().await?;
 
         if page_targets.is_empty() {
@@ -870,19 +994,19 @@ impl BrowserManager {
             self.active_page_index = 0;
             self.pin_active_target();
             self.enable_domains(&attach_result.session_id).await?;
-        } else if self.agent_group().is_some() {
-            // STRICT MULTI-AGENT ISOLATION (relay / the user's real Chrome).
-            // `page_targets` here are the USER's and OTHER agents' tabs. A tab
-            // group belongs to exactly ONE agent, so this session must NOT adopt
-            // any of them — it tracks ONLY tabs it creates (its own colored group)
-            // plus popups it opens. Adopting foreign tabs is precisely what let
-            // another concurrent agent's tab churn drop the tab we were driving and
-            // drift eval/click onto the wrong page (multi-agent failure). Open our
-            // own dedicated background tab in the session's group and pin it; the
-            // user's / other agents' tabs stay invisible to us.
+        } else if self.agent_group().is_some() && !scoped {
+            // STRICT MULTI-AGENT ISOLATION fallback (relay, but the group announce
+            // didn't take — e.g. an older relay). Without relay-side scoping,
+            // `page_targets` could be the USER's and OTHER agents' tabs, so this
+            // session must NOT adopt any of them — adopting foreign tabs is what let
+            // another agent's tab churn drop the tab we were driving (multi-agent
+            // failure). Open our own dedicated background tab and pin it instead.
             self.tab_new(None, None).await?;
         } else {
-            // A browser WE launched: every tab is ours, so adopt them all.
+            // Either a browser WE launched (every tab is ours) or the relay has
+            // scoped getTargets to our own tab group (#40) — so `page_targets` are
+            // all ours: adopt them (this restores follow-popup + cross-session
+            // adopt under isolation, since foreign tabs were already filtered out).
             for target in &page_targets {
                 let attach_result: AttachToTargetResult = self
                     .client
@@ -1580,7 +1704,11 @@ impl BrowserManager {
         // in the synthesized targetInfo), so don't adopt anything: the agent drives
         // only tabs it explicitly created, and pop-ups (e.g. an OAuth/login window)
         // are the user's. A launched browser (every tab ours) still follows pop-ups.
-        if self.agent_group().is_some() {
+        // Strict isolation only when on the relay WITHOUT group scoping: there a
+        // pop-up can't be told apart from a foreign tab, so adopt nothing. When the
+        // relay IS scoping (#40), getTargets returns only our group, so a tab that
+        // appeared after our own action is genuinely ours (a pop-up) — adopt it.
+        if self.agent_group().is_some() && !self.relay_scoped {
             return None;
         }
         let result: GetTargetsResult = self
@@ -1658,16 +1786,17 @@ impl BrowserManager {
             .collect();
         let live_ids: HashSet<String> = live.iter().map(|t| t.target_id.clone()).collect();
         let on_relay = self.agent_group().is_some();
+        // When the relay scopes getTargets to our group (#40), `live` is already
+        // only our own tabs, so adopting unknown ones is safe (a freshly-opened
+        // pop-up). Without scoping, keep strict isolation: never adopt a tab we
+        // didn't create — it belongs to the user or another agent.
+        let strict_isolation = on_relay && !self.relay_scoped;
 
         for target in &live {
             if self.update_page_target_info(target) {
                 continue;
             }
-            // STRICT MULTI-AGENT ISOLATION: on the relay (the user's real Chrome,
-            // shared with other agents), NEVER adopt a tab this session didn't
-            // create — it belongs to the user or another agent's group. Only a
-            // browser we launched (every tab ours) adopts unknown targets.
-            if on_relay {
+            if strict_isolation {
                 continue;
             }
             let attach_result: AttachToTargetResult = match self
@@ -1837,6 +1966,25 @@ impl BrowserManager {
         }
     }
 
+    /// Tell the relay which tab group this session owns so it can scope
+    /// `Target.getTargets` to us (issue #40). Only meaningful on the relay; a
+    /// no-op (returns false) on a launched/real-CDP connection. Sets and returns
+    /// `relay_scoped`: when true, the daemon can trust getTargets to contain only
+    /// our group and re-enable adopting new tabs (pop-ups, cross-session adopt).
+    async fn announce_group(&mut self) -> bool {
+        let Some(group) = self.agent_group() else {
+            self.relay_scoped = false;
+            return false;
+        };
+        let ok = self
+            .client
+            .send_command_typed::<_, Value>("ABRelay.setGroup", &json!({ "group": group }), None)
+            .await
+            .is_ok();
+        self.relay_scoped = ok;
+        ok
+    }
+
     pub async fn tab_new(
         &mut self,
         url: Option<&str>,
@@ -2630,6 +2778,7 @@ async fn initialize_lightpanda_manager(
             created_targets: HashSet::new(),
             active_target_id: None,
             relay_target_misses: HashMap::new(),
+            relay_scoped: false,
             next_tab_id: 1,
             capture_console: console_capture_enabled(),
         };

cli/src/native/relay.rs

@@ -52,6 +52,22 @@ pub struct RelayState {
     pending: HashMap<i64, (ClientId, Value)>,
     /// monotonic source of relay-global command ids
     next_global_id: i64,
+    /// Group-scoped isolation (issue #40). A tab group belongs to exactly one
+    /// agent/session; the relay scopes `Target.getTargets` per client to its own
+    /// group so the daemon can safely adopt new tabs (follow-popup, cross-session
+    /// adopt) without ever seeing the user's or another agent's tabs.
+    ///
+    /// clientId -> group name. A client that never announced a group (older
+    /// daemon) is absent here and gets the full, UNSCOPED target list — so this
+    /// is fully backward-compatible.
+    client_groups: HashMap<ClientId, String>,
+    /// targetId -> group name. Created tabs are tagged from `Target.createTarget`'s
+    /// `agentGroup`; an explicitly adopted tab is tagged to the adopter; a pop-up
+    /// inherits its opener's group (needs the extension to report `openerTargetId`).
+    target_group: HashMap<String, String>,
+    /// relay-global id of an in-flight `Target.createTarget` -> the `agentGroup`
+    /// it carried, so the reply's `targetId` can be tagged with that group.
+    pending_create: HashMap<i64, String>,
 }
 
 /// What to do with a raw CDP command received from a `CdpClient`.
@@ -95,6 +111,7 @@ impl RelayState {
     /// `pending` entries don't leak.
     pub fn drop_client(&mut self, client_id: ClientId) {
         self.pending.retain(|_, (cid, _)| *cid != client_id);
+        self.client_groups.remove(&client_id);
     }
 
     /// Route a raw CDP command `{id, method, params?, sessionId?}` from a
@@ -123,12 +140,28 @@ impl RelayState {
                     "jsVersion": ""
                 }
             })),
+            // Non-CDP control message: a daemon announces which tab group
+            // (session) it owns, so getTargets can be scoped to it (issue #40).
+            "ABRelay.setGroup" => {
+                if let Some(g) = params.get("group").and_then(|g| g.as_str()) {
+                    if !g.is_empty() {
+                        self.client_groups.insert(client_id, g.to_string());
+                    }
+                }
+                ClientRoute::Local(json!({ "id": id, "result": {} }))
+            }
             // Discovery is best-effort and event-driven in real CDP; abs only
             // reads the getTargets result, so an empty ack is enough here.
             "Target.setDiscoverTargets" | "Target.setAutoAttach" => {
                 ClientRoute::Local(json!({ "id": id, "result": {} }))
             }
-            "Target.getTargets" => {
+            // Unscoped discovery for EXPLICIT cross-group adoption (`chrome-use
+            // adopt`): returns every target the extension has attached, ignoring
+            // group scoping, so an agent can find a specific pre-existing tab (the
+            // user's, another session's) by URL/targetId and adopt it. Isolation
+            // is preserved because the daemon only acts on the one tab it then
+            // attaches (which the relay re-tags into the adopter's group).
+            "ABRelay.getAllTargets" => {
                 let infos: Vec<Value> = self
                     .targets
                     .values()
@@ -136,15 +169,44 @@ impl RelayState {
                     .collect();
                 ClientRoute::Local(json!({ "id": id, "result": { "targetInfos": infos } }))
             }
+            "Target.getTargets" => {
+                // Scope to the client's own group when it announced one; an
+                // un-announced (legacy) client gets the full list (back-compat).
+                let scoped = self.client_groups.get(&client_id).cloned();
+                let infos: Vec<Value> = self
+                    .targets
+                    .iter()
+                    .filter(|(tid, _)| match &scoped {
+                        Some(g) => self
+                            .target_group
+                            .get(*tid)
+                            .map(|tg| tg == g)
+                            .unwrap_or(false),
+                        None => true,
+                    })
+                    .map(|(_, t)| t.target_info.clone())
+                    .collect();
+                ClientRoute::Local(json!({ "id": id, "result": { "targetInfos": infos } }))
+            }
             "Target.attachToTarget" => {
                 let target_id = params
                     .get("targetId")
                     .and_then(|t| t.as_str())
                     .unwrap_or("");
                 match self.targets.get(target_id) {
-                    Some(entry) => ClientRoute::Local(
-                        json!({ "id": id, "result": { "sessionId": entry.session_id } }),
-                    ),
+                    Some(entry) => {
+                        let session_id = entry.session_id.clone();
+                        // Explicitly adopting a target makes it this client's
+                        // (cross-session adopt, #21) — tag it into the adopter's
+                        // group so it stays in that client's scoped getTargets and
+                        // isn't churn-pruned.
+                        if let Some(g) = self.client_groups.get(&client_id).cloned() {
+                            self.target_group.insert(target_id.to_string(), g);
+                        }
+                        ClientRoute::Local(
+                            json!({ "id": id, "result": { "sessionId": session_id } }),
+                        )
+                    }
                     None => ClientRoute::Local(json!({
                         "id": id,
                         "error": { "code": -32602, "message": format!("No such target {target_id}") }
@@ -157,6 +219,18 @@ impl RelayState {
                 self.next_global_id += 1;
                 let gid = self.next_global_id;
                 self.pending.insert(gid, (client_id, id));
+                // Remember the group a createTarget carries so the reply's
+                // targetId can be tagged to the creating session (issue #40).
+                if method == "Target.createTarget" {
+                    if let Some(g) = params.get("agentGroup").and_then(|g| g.as_str()) {
+                        if !g.is_empty() {
+                            self.pending_create.insert(gid, g.to_string());
+                            self.client_groups
+                                .entry(client_id)
+                                .or_insert_with(|| g.to_string());
+                        }
+                    }
+                }
                 ClientRoute::Forward(json!({
                     "id": gid,
                     "method": "forwardCDPCommand",
@@ -201,6 +275,17 @@ impl RelayState {
             && msg.get("method").is_none()
         {
             let gid = msg.get("id").and_then(|i| i.as_i64());
+            // A createTarget reply: tag the new tab's targetId with the group the
+            // command carried, so it lands in the creating session's scope (#40).
+            if let Some(g) = gid.and_then(|g| self.pending_create.remove(&g)) {
+                if let Some(tid) = msg
+                    .get("result")
+                    .and_then(|r| r.get("targetId"))
+                    .and_then(|t| t.as_str())
+                {
+                    self.target_group.insert(tid.to_string(), g);
+                }
+            }
             let (to, orig_id) = match gid.and_then(|g| self.pending.remove(&g)) {
                 Some((client_id, orig)) => (Some(client_id), orig),
                 // No mapping (stale/unknown id) — fall back to broadcasting with
@@ -241,6 +326,27 @@ impl RelayState {
                                 .and_then(|s| s.as_str())
                                 .unwrap_or("")
                                 .to_string();
+                            // Attribute the tab to a group for scoping (issue #40),
+                            // unless we already know it (createTarget tag). An
+                            // explicit `abGroup` from the extension wins; otherwise a
+                            // pop-up inherits its opener's group via `openerTargetId`.
+                            if !self.target_group.contains_key(tid) {
+                                if let Some(g) = info
+                                    .get("abGroup")
+                                    .and_then(|g| g.as_str())
+                                    .filter(|g| !g.is_empty())
+                                {
+                                    self.target_group.insert(tid.to_string(), g.to_string());
+                                } else if let Some(opener) = info
+                                    .get("openerTargetId")
+                                    .and_then(|o| o.as_str())
+                                    .filter(|o| !o.is_empty())
+                                {
+                                    if let Some(g) = self.target_group.get(opener).cloned() {
+                                        self.target_group.insert(tid.to_string(), g);
+                                    }
+                                }
+                            }
                             self.targets.insert(
                                 tid.to_string(),
                                 TargetEntry {
@@ -255,6 +361,15 @@ impl RelayState {
                 "Target.detachedFromTarget" => {
                     let gone = inner_params.get("sessionId").and_then(|s| s.as_str());
                     if let Some(gone) = gone {
+                        let gone_tids: Vec<String> = self
+                            .targets
+                            .iter()
+                            .filter(|(_, e)| e.session_id == gone)
+                            .map(|(tid, _)| tid.clone())
+                            .collect();
+                        for tid in gone_tids {
+                            self.target_group.remove(&tid);
+                        }
                         self.targets.retain(|_, e| e.session_id != gone);
                     }
                     return vec![];
@@ -557,4 +672,158 @@ mod tests {
             _ => panic!("expected ToExt"),
         }
     }
+
+    // === Group-scoped isolation (issue #40) ===
+
+    /// Drive the real create path: announce group, createTarget(agentGroup), feed
+    /// the ext reply (tags target→group) + the attachedToTarget event (creates the
+    /// entry). Returns nothing; mutates `s`.
+    fn create_in_group(s: &mut RelayState, client: ClientId, group: &str, tid: &str, sid: &str) {
+        s.route_client_command(
+            client,
+            &json!({ "id": 1, "method": "ABRelay.setGroup", "params": { "group": group } }),
+        );
+        let route = s.route_client_command(
+            client,
+            &json!({ "id": 2, "method": "Target.createTarget",
+                     "params": { "url": "about:blank", "agentGroup": group } }),
+        );
+        let gid = match route {
+            ClientRoute::Forward(env) => env["id"].as_i64().unwrap(),
+            _ => panic!("createTarget must forward"),
+        };
+        s.handle_ext_message(&json!({ "id": gid, "result": { "targetId": tid } }), "");
+        s.handle_ext_message(
+            &json!({ "method": "forwardCDPEvent", "params": {
+                "method": "Target.attachedToTarget",
+                "params": { "sessionId": sid, "targetInfo": {
+                    "targetId": tid, "type": "page", "url": "about:blank", "attached": true } } } }),
+            "",
+        );
+    }
+
+    fn get_target_ids(s: &mut RelayState, client: ClientId) -> Vec<String> {
+        match s.route_client_command(client, &json!({ "id": 9, "method": "Target.getTargets" })) {
+            ClientRoute::Local(v) => v["result"]["targetInfos"]
+                .as_array()
+                .unwrap()
+                .iter()
+                .map(|t| t["targetId"].as_str().unwrap().to_string())
+                .collect(),
+            _ => panic!("getTargets must be local"),
+        }
+    }
+
+    #[test]
+    fn get_targets_is_scoped_to_each_clients_group() {
+        let mut s = RelayState::new();
+        create_in_group(&mut s, 1, "agent-a", "ta", "sa");
+        create_in_group(&mut s, 2, "agent-b", "tb", "sb");
+        // Each client sees ONLY its own group's tab — never the other agent's.
+        assert_eq!(get_target_ids(&mut s, 1), vec!["ta"]);
+        assert_eq!(get_target_ids(&mut s, 2), vec!["tb"]);
+    }
+
+    #[test]
+    fn legacy_client_without_group_sees_all_targets() {
+        let mut s = RelayState::new();
+        create_in_group(&mut s, 1, "agent-a", "ta", "sa");
+        create_in_group(&mut s, 2, "agent-b", "tb", "sb");
+        // Client 3 never announced a group → full, unscoped list (back-compat).
+        let mut all = get_target_ids(&mut s, 3);
+        all.sort();
+        assert_eq!(all, vec!["ta", "tb"]);
+    }
+
+    #[test]
+    fn popup_inherits_opener_group_and_is_visible_to_that_client_only() {
+        let mut s = RelayState::new();
+        create_in_group(&mut s, 1, "agent-a", "ta", "sa");
+        create_in_group(&mut s, 2, "agent-b", "tb", "sb");
+        // A pop-up that agent-a's tab opened: extension reports openerTargetId=ta.
+        s.handle_ext_message(
+            &json!({ "method": "forwardCDPEvent", "params": {
+                "method": "Target.attachedToTarget",
+                "params": { "sessionId": "sp", "targetInfo": {
+                    "targetId": "tp", "type": "page", "url": "https://oauth.example/",
+                    "attached": true, "openerTargetId": "ta" } } } }),
+            "",
+        );
+        // Only agent-a sees the pop-up; agent-b never does.
+        let mut a = get_target_ids(&mut s, 1);
+        a.sort();
+        assert_eq!(a, vec!["ta", "tp"]);
+        assert_eq!(get_target_ids(&mut s, 2), vec!["tb"]);
+    }
+
+    #[test]
+    fn explicit_attach_tags_target_into_adopter_group() {
+        let mut s = RelayState::new();
+        // A pre-existing, ungrouped tab the extension reported (e.g. user's tab).
+        s.handle_ext_message(
+            &json!({ "method": "forwardCDPEvent", "params": {
+                "method": "Target.attachedToTarget",
+                "params": { "sessionId": "su", "targetInfo": {
+                    "targetId": "tu", "type": "page", "url": "https://user.example/", "attached": true } } } }),
+            "",
+        );
+        // Client 1 (group agent-a) explicitly adopts it by targetId (#21).
+        s.route_client_command(
+            1,
+            &json!({ "id": 1, "method": "ABRelay.setGroup", "params": { "group": "agent-a" } }),
+        );
+        s.route_client_command(
+            1,
+            &json!({ "id": 2, "method": "Target.attachToTarget", "params": { "targetId": "tu" } }),
+        );
+        // Now it's in agent-a's scope and survives the scoped getTargets.
+        assert_eq!(get_target_ids(&mut s, 1), vec!["tu"]);
+        // A different agent still doesn't see it.
+        s.route_client_command(
+            2,
+            &json!({ "id": 1, "method": "ABRelay.setGroup", "params": { "group": "agent-b" } }),
+        );
+        assert!(get_target_ids(&mut s, 2).is_empty());
+    }
+
+    #[test]
+    fn get_all_targets_is_unscoped() {
+        let mut s = RelayState::new();
+        create_in_group(&mut s, 1, "agent-a", "ta", "sa");
+        create_in_group(&mut s, 2, "agent-b", "tb", "sb");
+        // Client 1's scoped getTargets sees only its own group...
+        assert_eq!(get_target_ids(&mut s, 1), vec!["ta"]);
+        // ...but ABRelay.getAllTargets returns EVERY target regardless of group
+        // (for explicit cross-group adoption).
+        let all = match s
+            .route_client_command(1, &json!({ "id": 1, "method": "ABRelay.getAllTargets" }))
+        {
+            ClientRoute::Local(v) => {
+                let mut ids: Vec<String> = v["result"]["targetInfos"]
+                    .as_array()
+                    .unwrap()
+                    .iter()
+                    .map(|t| t["targetId"].as_str().unwrap().to_string())
+                    .collect();
+                ids.sort();
+                ids
+            }
+            _ => panic!("getAllTargets must be local"),
+        };
+        assert_eq!(all, vec!["ta", "tb"]);
+    }
+
+    #[test]
+    fn detach_clears_target_group() {
+        let mut s = RelayState::new();
+        create_in_group(&mut s, 1, "agent-a", "ta", "sa");
+        assert_eq!(get_target_ids(&mut s, 1), vec!["ta"]);
+        s.handle_ext_message(
+            &json!({ "method": "forwardCDPEvent", "params": {
+                "method": "Target.detachedFromTarget", "params": { "sessionId": "sa" } } }),
+            "",
+        );
+        assert!(get_target_ids(&mut s, 1).is_empty());
+        assert!(!s.target_group.contains_key("ta"));
+    }
 }

cli/src/output.rs

@@ -3375,6 +3375,10 @@ Tabs:
                              stable targetId, no reload — preserves in-page state
   open <url> --reuse-tab     Reuse an existing tab on that URL instead of spawning
                              a duplicate (matches origin+path; preserves state)
+  adopt <url|targetId>       Read a PRE-EXISTING tab (the user's own, or another
+                             session's) WITHOUT opening a new one — matches by URL
+                             substring or stable targetId, then drives it. e.g.
+                             `adopt "github.com/owner/repo"`
 
 Diff:
   diff snapshot              Compare current vs last snapshot

extensions/ab-connect/background.js

@@ -81,6 +81,35 @@ async function groupTabInto(tabId, name) {
   groupIdByName.set(name, gid)
 }
 
+// Group-scoped relay isolation hints (issue #40). The relay scopes
+// Target.getTargets per agent by tab group; report two things in the synthesized
+// targetInfo so it can attribute each tab:
+//   - abGroup: the tab's Chrome tab-group TITLE (= the owning session name), so
+//     the relay can re-attribute existing tabs after a restart (createTarget
+//     tagging won't re-run for already-open tabs).
+//   - openerTargetId: the targetId of the tab that opened this one, so a pop-up
+//     (window.open / target=_blank / OAuth result) inherits its opener's group
+//     and the agent that opened it can follow it — without foreign tabs leaking.
+// Best-effort: any failure yields empty strings, which the relay ignores.
+async function tabScopeHints(tabId) {
+  let openerTargetId = ''
+  let abGroup = ''
+  try {
+    const t = await chrome.tabs.get(tabId)
+    if (t) {
+      if (typeof t.openerTabId === 'number') {
+        const op = tabs.get(t.openerTabId)
+        if (op) openerTargetId = op.targetId
+      }
+      if (t.groupId != null && t.groupId >= 0 && chrome.tabGroups) {
+        const g = await chrome.tabGroups.get(t.groupId).catch(() => null)
+        if (g && g.title) abGroup = g.title
+      }
+    }
+  } catch {}
+  return { openerTargetId, abGroup }
+}
+
 function postToHost(msg) {
   try {
     if (port) port.postMessage(msg)
@@ -126,7 +155,7 @@ function connectHost() {
   } catch {}
   // Tell the daemon about everything we already have attached, then attach
   // anything new.
-  reannounceAttachedTabs()
+  void reannounceAttachedTabs()
   void attachAllTabs()
 }
 
@@ -140,7 +169,7 @@ async function onHostMessage(msg) {
   // Daemon (re)connected — (re)attach and announce every tab so it discovers
   // the user's existing tabs rather than racing an empty target list.
   if (msg.method === 'attachAll') {
-    reannounceAttachedTabs()
+    void reannounceAttachedTabs()
     await attachAllTabs()
     return
   }
@@ -387,12 +416,16 @@ async function attachTab(tabId) {
   sessionToTab.set(sessionId, tabId)
   rememberSessionTarget(sessionId, targetId)
   setBadge(tabId, port ? 'on' : 'connecting')
+  const { openerTargetId, abGroup } = await tabScopeHints(tabId)
   postToHost({
     method: 'forwardCDPEvent',
     params: {
       sessionId,
       method: 'Target.attachedToTarget',
-      params: { sessionId, targetInfo: { ...targetInfo, attached: true } },
+      params: {
+        sessionId,
+        targetInfo: { ...targetInfo, attached: true, openerTargetId, abGroup },
+      },
     },
   })
   return entry
@@ -434,14 +467,32 @@ async function attachAllTabs() {
   }
 }
 
-function reannounceAttachedTabs() {
-  for (const [, entry] of tabs.entries()) {
+async function reannounceAttachedTabs() {
+  for (const [tabId, entry] of tabs.entries()) {
+    // Re-send the group hint too (issue #40) so the relay can rebuild its
+    // targetId→group map after its own restart (createTarget tagging won't
+    // re-run for tabs that are already open). Include the live url/title so the
+    // relay's target list stays matchable by URL after a reconnect (otherwise a
+    // reannounced tab shows a blank url and `adopt <url>` can't find it).
+    const { openerTargetId, abGroup } = await tabScopeHints(tabId)
+    let url = ''
+    let title = ''
+    try {
+      const t = await chrome.tabs.get(tabId)
+      if (t) {
+        url = t.url || t.pendingUrl || ''
+        title = t.title || ''
+      }
+    } catch {}
     postToHost({
       method: 'forwardCDPEvent',
       params: {
         sessionId: entry.sessionId,
         method: 'Target.attachedToTarget',
-        params: { sessionId: entry.sessionId, targetInfo: { targetId: entry.targetId, type: 'page', attached: true } },
+        params: {
+          sessionId: entry.sessionId,
+          targetInfo: { targetId: entry.targetId, type: 'page', url, title, attached: true, openerTargetId, abGroup },
+        },
       },
     })
   }

extensions/ab-connect/manifest.json

@@ -1,7 +1,7 @@
 {
   "manifest_version": 3,
   "name": "chrome-use",
-  "version": "0.4.9",
+  "version": "0.4.11",
   "description": "Let chrome-use drive your logged-in Chrome \u2014 install once, no token, no per-use confirmation.",
   "key": "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA6vQIyscGIPYPZdSpPwPL0+0gxUROyRgCpmvCSDoc8XUm4qm97VbKnD9Ijc1lV22lNWZtE78gaRjt6BeSfuMgnBymnhLKjN1gU6AI5QUU0mrJyeHdWKvrKQR5FmsM2A7Xr1ykE2SiiS8zNUS3Y/6O5l+Nva7wrVy6E4a2dkBVQkOsu+DV+nEZvhIyuDY5D5SPXqNwUTWTaglwj5mjvHz36xSwCWlPmrtJ+ED0AUyrb2z4GIOmvk4kqtBVrh/UD058klLo4CkYOnIybB5aV6WYuwarfPY4bF/dLggPem+ewLNTUNBuwrxj/A4nUv0LJTuRO8rR7f8WR9qnRCY0Ic5saQIDAQAB",
   "icons": {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "chrome-use",
-  "version": "1.5.21",
+  "version": "1.5.23",
   "description": "chrome-use — drive your real, logged-in Chrome from any AI agent, stealth by default",
   "type": "module",
   "packageManager": "pnpm@11.1.3",