feat: add multi-agent collaboration tabs

next.config.ts

@@ -31,7 +31,7 @@ const nextConfig: NextConfig = {
   images: {
     unoptimized: true,
   },
-  assetPrefix: isProd ? undefined : `http://${internalHost}:3000`,
+  assetPrefix: isProd ? undefined : `http://${internalHost}:4000`,
 }
 
 export default withNextIntl(nextConfig)

src-tauri/src/commands/conversations.rs

@@ -2479,6 +2479,7 @@ mod tests {
             position: 0,
             is_active: false,
             is_pinned: true,
+            title_override: None,
         }
     }
 
@@ -2495,8 +2496,10 @@ mod tests {
         let (broadcaster, emitter) = sync_test_emitter();
         let mut rx = broadcaster.subscribe();
 
+        let mut delegated_tab = conv_tab(folder_id, c1, AgentType::ClaudeCode);
+        delegated_tab.title_override = Some("Backend verifier".to_string());
         let items = vec![
-            conv_tab(folder_id, c1, AgentType::ClaudeCode),
+            delegated_tab,
             conv_tab(folder_id, c2, AgentType::Codex),
             // A draft (conversation_id == None) — must NOT persist.
             OpenedTab {
@@ -2507,6 +2510,7 @@ mod tests {
                 position: 2,
                 is_active: true,
                 is_pinned: true,
+                title_override: None,
             },
         ];
         let outcome = save_opened_tabs_core(&db.conn, &emitter, items, 0, "win-a".into())
@@ -2521,10 +2525,15 @@ mod tests {
         assert_eq!(evt.payload["version"], 1);
         assert_eq!(evt.payload["origin"], "win-a");
         assert_eq!(evt.payload["tabs"].as_array().unwrap().len(), 2);
+        assert_eq!(evt.payload["tabs"][0]["title_override"], "Backend verifier");
 
         let snap = list_opened_tabs_core(&db.conn).await.expect("list");
         assert_eq!(snap.items.len(), 2);
         assert_eq!(snap.version, 1);
+        assert_eq!(
+            snap.items[0].title_override.as_deref(),
+            Some("Backend verifier")
+        );
     }
 
     #[tokio::test]

src-tauri/src/db/entities/opened_tab.rs

@@ -11,6 +11,7 @@ pub struct Model {
     pub position: i32,
     pub is_active: bool,
     pub is_pinned: bool,
+    pub title_override: Option<String>,
     pub created_at: DateTimeUtc,
     pub updated_at: DateTimeUtc,
 }

src-tauri/src/db/migration/m20260617_000001_opened_tab_title_override.rs

@@ -0,0 +1,35 @@
+use sea_orm_migration::prelude::*;
+
+#[derive(DeriveMigrationName)]
+pub struct Migration;
+
+#[async_trait::async_trait]
+impl MigrationTrait for Migration {
+    async fn up(&self, manager: &SchemaManager) -> Result<(), DbErr> {
+        manager
+            .alter_table(
+                Table::alter()
+                    .table(OpenedTab::Table)
+                    .add_column(ColumnDef::new(OpenedTab::TitleOverride).text().null())
+                    .to_owned(),
+            )
+            .await
+    }
+
+    async fn down(&self, manager: &SchemaManager) -> Result<(), DbErr> {
+        manager
+            .alter_table(
+                Table::alter()
+                    .table(OpenedTab::Table)
+                    .drop_column(OpenedTab::TitleOverride)
+                    .to_owned(),
+            )
+            .await
+    }
+}
+
+#[derive(DeriveIden)]
+enum OpenedTab {
+    Table,
+    TitleOverride,
+}

src-tauri/src/db/migration/mod.rs

@@ -21,6 +21,7 @@ mod m20260607_000001_folder_parent_id;
 mod m20260608_000001_conversation_title_locked;
 mod m20260610_000001_conversation_pinned_at;
 mod m20260611_000001_folder_is_chat;
+mod m20260617_000001_opened_tab_title_override;
 pub struct Migrator;
 
 #[async_trait::async_trait]
@@ -48,6 +49,7 @@ impl MigratorTrait for Migrator {
             Box::new(m20260608_000001_conversation_title_locked::Migration),
             Box::new(m20260610_000001_conversation_pinned_at::Migration),
             Box::new(m20260611_000001_folder_is_chat::Migration),
+            Box::new(m20260617_000001_opened_tab_title_override::Migration),
         ]
     }
 }

src-tauri/src/db/service/tab_service.rs

@@ -68,6 +68,7 @@ pub async fn list_all_tabs<C: ConnectionTrait>(conn: &C) -> Result<Vec<OpenedTab
                 position: r.position,
                 is_active: r.is_active,
                 is_pinned: r.is_pinned,
+                title_override: r.title_override,
             })
         })
         .collect())
@@ -121,6 +122,12 @@ pub async fn save_all_tabs<C: ConnectionTrait>(
         } else {
             false
         };
+        let title_override = item
+            .title_override
+            .as_deref()
+            .map(str::trim)
+            .filter(|s| !s.is_empty())
+            .map(ToOwned::to_owned);
 
         let active = opened_tab::ActiveModel {
             id: NotSet,
@@ -130,6 +137,7 @@ pub async fn save_all_tabs<C: ConnectionTrait>(
             position: Set(item.position),
             is_active: Set(is_active),
             is_pinned: Set(item.is_pinned),
+            title_override: Set(title_override),
             created_at: Set(now),
             updated_at: Set(now),
         };

src-tauri/src/models/folder.rs

@@ -39,6 +39,11 @@ pub struct OpenedTab {
     pub position: i32,
     pub is_active: bool,
     pub is_pinned: bool,
+    /// Optional display-title override for restored/synced tabs. Used by
+    /// delegated sub-agent tabs so their tab label can remain the role/task
+    /// name instead of falling back to the persisted conversation title.
+    #[serde(default)]
+    pub title_override: Option<String>,
 }
 
 /// Response for `list_opened_tabs`: the persisted tab set plus the current

src-tauri/tauri.conf.json

@@ -4,8 +4,8 @@
   "version": "0.15.12",
   "identifier": "app.codeg",
   "build": {
-    "beforeDevCommand": "pnpm tauri:before-dev",
-    "devUrl": "http://localhost:3000",
+    "beforeDevCommand": "pnpm tauri:prepare-sidecars && pnpm exec next dev --turbopack -p 4000",
+    "devUrl": "http://localhost:4000",
     "beforeBuildCommand": "pnpm tauri:before-build",
     "frontendDist": "../out"
   },

src/components/chat/sub-agent-overlay.test.tsx

@@ -29,6 +29,12 @@ vi.mock("@/contexts/acp-connections-context", async () => {
   }
 })
 
+const mockOpenConversationTab = vi.fn(() => Promise.resolve())
+
+vi.mock("@/hooks/use-open-conversation-tab", () => ({
+  useOpenConversationTab: () => mockOpenConversationTab,
+}))
+
 // SubAgentSessionDialog pulls in MessageListView + the runtime provider tree.
 // Stub it to a sentinel exposing the open state + target conversation id.
 vi.mock("@/components/message/sub-agent-session-dialog", () => ({
@@ -84,6 +90,8 @@ function source(
 describe("SubAgentOverlay", () => {
   beforeEach(() => {
     bindings = {}
+    mockOpenConversationTab.mockReset()
+    mockOpenConversationTab.mockResolvedValue(undefined)
     mockedHook.mockReset()
     mockedHook.mockImplementation((id: string) => ({
       binding: bindings[id],

src/components/chat/sub-agent-overlay.tsx

@@ -17,7 +17,8 @@
 
 import { memo, useState } from "react"
 import { useTranslations } from "next-intl"
-import { BotIcon, ChevronDownIcon } from "lucide-react"
+import { BotIcon, ChevronDownIcon, PanelRight } from "lucide-react"
+import { toast } from "sonner"
 
 import { AgentIcon } from "@/components/agent-icon"
 import { CollapsedOverlayChip } from "@/components/chat/collapsed-overlay-chip"
@@ -29,6 +30,7 @@ import {
   useDelegationCardModel,
   type DelegationCardSource,
 } from "@/hooks/use-delegation-card-model"
+import { useOpenConversationTab } from "@/hooks/use-open-conversation-tab"
 import { AGENT_LABELS } from "@/lib/types"
 
 interface SubAgentOverlayProps {
@@ -124,6 +126,7 @@ const SubAgentOverlayRow = memo(function SubAgentOverlayRow({
     childConversationId,
     childConnectionId,
   } = useDelegationCardModel(source)
+  const openConversationTab = useOpenConversationTab()
 
   // Unlike the inline DelegatedSubThread (which falls through to the generic
   // tool renderer when nothing resolves), the overlay always renders one row
@@ -132,6 +135,13 @@ const SubAgentOverlayRow = memo(function SubAgentOverlayRow({
   // degrade gracefully: unknown agent → neutral dot + "Sub-agent" label,
   // missing child id → non-clickable.
   const clickable = childConversationId != null
+  const handleOpenTab = () => {
+    if (childConversationId == null) return
+    openConversationTab(childConversationId, { title: task }).catch((err) => {
+      console.error("[SubAgentOverlay] open conversation tab failed:", err)
+      toast.error(t("openInTabFailed"))
+    })
+  }
 
   const rowBody = (
     <div className="min-w-0 flex-1 space-y-1">
@@ -166,18 +176,31 @@ const SubAgentOverlayRow = memo(function SubAgentOverlayRow({
   return (
     <>
       {clickable ? (
-        <button
-          type="button"
+        <div
           data-testid="sub-agent-row"
-          onClick={() => setDialogOpen(true)}
-          className="flex w-full items-center gap-2 rounded-lg border bg-transparent px-2 py-1.5 text-left transition-colors hover:bg-muted/60"
-          // No aria-label: let the row content (agent name + task) name the
-          // button so screen readers can tell rows apart. `title` stays for the
-          // pointer tooltip.
-          title={t("openDetail")}
+          className="flex w-full items-stretch overflow-hidden rounded-lg border bg-transparent transition-colors hover:bg-muted/60"
         >
-          {rowBody}
-        </button>
+          <button
+            type="button"
+            onClick={() => setDialogOpen(true)}
+            className="flex min-w-0 flex-1 items-center gap-2 px-2 py-1.5 text-left"
+            // No aria-label: let the row content (agent name + task) name the
+            // button so screen readers can tell rows apart. `title` stays for the
+            // pointer tooltip.
+            title={t("openDetail")}
+          >
+            {rowBody}
+          </button>
+          <button
+            type="button"
+            onClick={handleOpenTab}
+            className="flex shrink-0 items-center border-l px-2 text-muted-foreground transition-colors hover:bg-muted hover:text-foreground"
+            title={t("openInTab")}
+            aria-label={t("openInTab")}
+          >
+            <PanelRight className="h-3.5 w-3.5" />
+          </button>
+        </div>
       ) : (
         <div
           data-testid="sub-agent-row"

src/components/message/delegated-sub-thread.test.tsx

@@ -15,6 +15,7 @@ vi.mock("@/hooks/use-delegated-sub-session", () => ({
 // connections store (to badge "awaiting approval"). It renders no body and
 // answers no permission inline — so those are the only contexts to stub.
 let mockChildConnection: unknown = undefined
+const mockOpenConversationTab = vi.fn(() => Promise.resolve())
 
 vi.mock("@/contexts/acp-connections-context", async () => {
   const actual = await vi.importActual<
@@ -31,6 +32,10 @@ vi.mock("@/contexts/acp-connections-context", async () => {
   }
 })
 
+vi.mock("@/hooks/use-open-conversation-tab", () => ({
+  useOpenConversationTab: () => mockOpenConversationTab,
+}))
+
 // SubAgentSessionDialog pulls in MessageListView + useConversationRuntime, which
 // would require the full runtime provider tree. Stub it to a sentinel exposing
 // the open state + child id so we can assert the "Open conversation" button
@@ -109,6 +114,8 @@ function childConnWith(pendingPermission: unknown) {
 describe("DelegatedSubThread", () => {
   beforeEach(() => {
     mockChildConnection = undefined
+    mockOpenConversationTab.mockReset()
+    mockOpenConversationTab.mockResolvedValue(undefined)
     mockedHook.mockReturnValue({
       binding: undefined,
       detail: null,
@@ -353,6 +360,8 @@ describe("DelegatedSubThread", () => {
 describe("DelegatedSubThread (async ack semantics)", () => {
   beforeEach(() => {
     mockChildConnection = undefined
+    mockOpenConversationTab.mockReset()
+    mockOpenConversationTab.mockResolvedValue(undefined)
     mockedHook.mockReturnValue({
       binding: undefined,
       detail: null,

src/components/message/delegated-sub-thread.tsx

@@ -19,15 +19,17 @@
  */
 
 import { useState } from "react"
-import { Eye } from "lucide-react"
+import { Eye, PanelRight } from "lucide-react"
 import { useTranslations } from "next-intl"
+import { toast } from "sonner"
 
 import { AgentIcon } from "@/components/agent-icon"
 import { AGENT_LABELS } from "@/lib/types"
 import type { ToolCallState } from "@/lib/adapters/ai-elements-adapter"
 import { StatusBadge } from "@/components/message/delegation-status-badge"
 import { SubAgentSessionDialog } from "@/components/message/sub-agent-session-dialog"
 import { useDelegationCardModel } from "@/hooks/use-delegation-card-model"
+import { useOpenConversationTab } from "@/hooks/use-open-conversation-tab"
 
 interface Props {
   parentToolUseId: string
@@ -77,6 +79,7 @@ export function DelegatedSubThread({
     state,
     meta,
   })
+  const openConversationTab = useOpenConversationTab()
 
   // A snapshot replay with an empty/unparseable input AND no live binding has
   // no useful card to draw — fall through to the standard renderer instead of
@@ -85,6 +88,14 @@ export function DelegatedSubThread({
     return null
   }
 
+  const handleOpenTab = () => {
+    if (childConversationId == null) return
+    openConversationTab(childConversationId, { title: task }).catch((err) => {
+      console.error("[DelegatedSubThread] open conversation tab failed:", err)
+      toast.error(t("openInTabFailed"))
+    })
+  }
+
   return (
     <div
       data-testid="delegated-sub-thread"
@@ -122,18 +133,32 @@ export function DelegatedSubThread({
           </div>
         </div>
         {childConversationId != null && (
-          <button
-            type="button"
-            onClick={() => setDialogOpen(true)}
-            className="shrink-0 flex items-center gap-1.5 px-3 border-l border-border text-xs font-medium text-foreground/80 hover:bg-muted/60 hover:text-foreground transition-colors"
-            title={t("openDetail")}
-            aria-label={t("openDetail")}
-          >
-            <Eye className="h-3.5 w-3.5" />
-            <span className="hidden @[24rem]/delegcard:inline">
-              {t("openDetail")}
-            </span>
-          </button>
+          <div className="shrink-0 flex border-l border-border">
+            <button
+              type="button"
+              onClick={() => setDialogOpen(true)}
+              className="flex items-center gap-1.5 px-3 text-xs font-medium text-foreground/80 transition-colors hover:bg-muted/60 hover:text-foreground"
+              title={t("openDetail")}
+              aria-label={t("openDetail")}
+            >
+              <Eye className="h-3.5 w-3.5" />
+              <span className="hidden @[24rem]/delegcard:inline">
+                {t("openDetail")}
+              </span>
+            </button>
+            <button
+              type="button"
+              onClick={handleOpenTab}
+              className="flex items-center gap-1.5 border-l border-border px-3 text-xs font-medium text-foreground/80 transition-colors hover:bg-muted/60 hover:text-foreground"
+              title={t("openInTab")}
+              aria-label={t("openInTab")}
+            >
+              <PanelRight className="h-3.5 w-3.5" />
+              <span className="hidden @[30rem]/delegcard:inline">
+                {t("openInTab")}
+              </span>
+            </button>
+          </div>
         )}
       </div>
       {childConversationId != null && (