diff --git a/apps/desktop-tauri/scripts/proof-scenarios.json b/apps/desktop-tauri/scripts/proof-scenarios.json
index c576456a44..99ca76f18d 100644
--- a/apps/desktop-tauri/scripts/proof-scenarios.json
+++ b/apps/desktop-tauri/scripts/proof-scenarios.json
@@ -736,6 +736,16 @@
         { "expectText": "%" },
         { "screenshot": "floatbar" }
       ]
+    },
+    {
+      "name": "tray-agent-sessions-hosts",
+      "query": "window=main&fixture=agent-sessions-hosts",
+      "size": [310, 1032],
+      "steps": [
+        { "expectText": ["WORKSTATION-A — 2", "BUILD-BOX — 1", "LAB-HOST — unreachable", "ssh: connection timed out", "example-project"] },
+        { "expectNoText": "LAB-HOST — 0" },
+        { "screenshot": "tray-agent-sessions-hosts", "clip": "panel" }
+      ]
     }
   ]
 }
diff --git a/apps/desktop-tauri/src/components/AgentSessions.test.tsx b/apps/desktop-tauri/src/components/AgentSessions.test.tsx
index 9d4940bc5e..4db581081b 100644
--- a/apps/desktop-tauri/src/components/AgentSessions.test.tsx
+++ b/apps/desktop-tauri/src/components/AgentSessions.test.tsx
@@ -105,4 +105,66 @@ describe("AgentSessions", () => {
 
     expect(await screen.findByText("AgentSessionsProviderPi")).toBeTruthy();
   });
+
+  it("groups sessions under one header per host with its session count", async () => {
+    api.listAgentSessions.mockResolvedValue({
+      status: "hosts",
+      hosts: [
+        {
+          host: "DESKTOP",
+          sessions: [
+            session({ id: "1", host: "DESKTOP", workspace: { cwd: null, projectName: "alpha" } }),
+            session({ id: "2", host: "DESKTOP", workspace: { cwd: null, projectName: "beta" } }),
+          ],
+          error: null,
+        },
+        {
+          host: "LAPTOP",
+          sessions: [session({ id: "3", host: "LAPTOP", workspace: { cwd: null, projectName: "gamma" } })],
+          error: null,
+        },
+      ],
+    });
+    render(<AgentSessions />);
+
+    const desktopHeader = await screen.findByText("DESKTOP — 2");
+    const laptopHeader = await screen.findByText("LAPTOP — 1");
+    const alpha = screen.getByText("alpha");
+    const gamma = screen.getByText("gamma");
+    // Each host's rows follow its own header, and the hosts stay in order.
+    expect(desktopHeader.compareDocumentPosition(alpha) & Node.DOCUMENT_POSITION_FOLLOWING).toBeTruthy();
+    expect(alpha.compareDocumentPosition(laptopHeader) & Node.DOCUMENT_POSITION_FOLLOWING).toBeTruthy();
+    expect(laptopHeader.compareDocumentPosition(gamma) & Node.DOCUMENT_POSITION_FOLLOWING).toBeTruthy();
+  });
+
+  it("shows an unreachable host as its own row with the error", async () => {
+    api.listAgentSessions.mockResolvedValue({
+      status: "hosts",
+      hosts: [
+        {
+          host: "DESKTOP",
+          sessions: [session({ id: "1", workspace: { cwd: null, projectName: "alpha" } })],
+          error: null,
+        },
+        { host: "BUILD-BOX", sessions: [], error: "ssh: connect timed out" },
+      ],
+    });
+    render(<AgentSessions />);
+
+    expect(await screen.findByText("BUILD-BOX — AgentSessionsHostUnreachable")).toBeTruthy();
+    expect(screen.getByText("ssh: connect timed out").className).toContain("agent-sessions__error");
+    expect(screen.queryByText("BUILD-BOX — 0")).toBeNull();
+    expect(screen.getByText("DESKTOP — 1")).toBeTruthy();
+  });
+
+  it("keeps a reachable host with no sessions visible as a zero-count header", async () => {
+    api.listAgentSessions.mockResolvedValue({
+      status: "hosts",
+      hosts: [{ host: "IDLE-BOX", sessions: [], error: null }],
+    });
+    render(<AgentSessions />);
+
+    expect(await screen.findByText("IDLE-BOX — 0")).toBeTruthy();
+    expect(screen.getByText("AgentSessionsEmpty")).toBeTruthy();
+  });
 });
diff --git a/apps/desktop-tauri/src/components/AgentSessions.tsx b/apps/desktop-tauri/src/components/AgentSessions.tsx
index 73f8b336ca..d6ef9761c1 100644
--- a/apps/desktop-tauri/src/components/AgentSessions.tsx
+++ b/apps/desktop-tauri/src/components/AgentSessions.tsx
@@ -33,9 +33,6 @@ export default function AgentSessions() {
   if (result?.status === "disabled") return null;
   const hosts = result?.status === "hosts" ? result.hosts : [];
   const sessions = hosts.flatMap((host) => host.sessions);
-  const hostErrors = hosts.flatMap((host) =>
-    host.error ? [`${host.host}: ${host.error}`] : [],
-  );
 
   const focus = (session: AgentSession) => {
     void focusAgentSession(session).then((focusResult) => {
@@ -53,26 +50,41 @@ export default function AgentSessions() {
       {result && sessions.length === 0 && (
         <p>{t("AgentSessionsEmpty")}</p>
       )}
-      {sessions.map((session) => (
-        <button
-          type="button"
-          className="agent-sessions__row"
-          key={`${session.host}:${session.provider}:${session.id}`}
-          onClick={() => focus(session)}
-        >
-          <span>{sessionLabel(session)}</span>
-          <span
-            className="agent-sessions__name"
-            title={session.sessionName ?? session.workspace.projectName ?? session.host}
+      {hosts.map((host) => (
+        <div className="agent-sessions__host" key={host.host}>
+          {/* Upstream agentSessionsSection: one header per host, then its rows. */}
+          <div
+            className={
+              host.error
+                ? "agent-sessions__host-header agent-sessions__host-header--unreachable"
+                : "agent-sessions__host-header"
+            }
           >
-            {session.sessionName ?? session.workspace.projectName ?? session.host}
-          </span>
-          <span>{session.state}</span>
-        </button>
-      ))}
-      {[...hostErrors, ...(error ? [error] : [])].map((message) => (
-        <p className="agent-sessions__error" key={message}>{message}</p>
+            {host.error
+              ? `${host.host} — ${t("AgentSessionsHostUnreachable")}`
+              : `${host.host} — ${host.sessions.length}`}
+          </div>
+          {host.error && <p className="agent-sessions__error">{host.error}</p>}
+          {host.sessions.map((session) => (
+            <button
+              type="button"
+              className="agent-sessions__row"
+              key={`${session.host}:${session.provider}:${session.id}`}
+              onClick={() => focus(session)}
+            >
+              <span>{sessionLabel(session)}</span>
+              <span
+                className="agent-sessions__name"
+                title={session.sessionName ?? session.workspace.projectName ?? session.host}
+              >
+                {session.sessionName ?? session.workspace.projectName ?? session.host}
+              </span>
+              <span>{session.state}</span>
+            </button>
+          ))}
+        </div>
       ))}
+      {error && <p className="agent-sessions__error">{error}</p>}
     </section>
   );
 }
diff --git a/apps/desktop-tauri/src/i18n/keyGroups/core.ts b/apps/desktop-tauri/src/i18n/keyGroups/core.ts
index 860e6b7169..842187c7e5 100644
--- a/apps/desktop-tauri/src/i18n/keyGroups/core.ts
+++ b/apps/desktop-tauri/src/i18n/keyGroups/core.ts
@@ -744,6 +744,7 @@ export const CORE_LOCALE_KEYS = [
   "AgentSessionsSshHostsHelper",
   "AgentSessionsLoading",
   "AgentSessionsEmpty",
+  "AgentSessionsHostUnreachable",
   "UpdatesTitle",
   "AboutBuilt",
   "SectionLinks",
diff --git a/apps/desktop-tauri/src/proof/fixtures/scenarios.ts b/apps/desktop-tauri/src/proof/fixtures/scenarios.ts
index 99aaa49558..0c5dc71977 100644
--- a/apps/desktop-tauri/src/proof/fixtures/scenarios.ts
+++ b/apps/desktop-tauri/src/proof/fixtures/scenarios.ts
@@ -1,5 +1,7 @@
 import type {
   AccountUsageEntryBridge,
+  AgentSession,
+  AgentSessionDiscoveryResult,
   ClaudeAccount,
   ClaudeSwapAccount,
   ClaudeSwapAccountsState,
@@ -54,6 +56,7 @@ export const PROOF_SCENARIO_NAMES = [
   "vercel",
   "vercel-team-id-invalid",
   "kimi-bonus-credits",
+  "agent-sessions-hosts",
 ] as const;
 
 export type ProofScenarioName = (typeof PROOF_SCENARIO_NAMES)[number];
@@ -92,6 +95,8 @@ export interface ProofScenario {
   workspaceIds?: Record<string, string>;
   /** Error a workspace-value save rejects with, by provider id; absent means saves succeed. */
   workspaceIdSaveErrors?: Record<string, string>;
+  /** Agent-session discovery served by `list_agent_sessions`; absent means disabled. */
+  agentSessions?: AgentSessionDiscoveryResult;
 }
 
 export interface LocalSpendFixture {
@@ -1147,6 +1152,55 @@ function kimiBonusCreditsScenario(now: Date): ProofScenario {
   };
 }
 
+function proofAgentSession(
+  id: string,
+  host: string,
+  provider: AgentSession["provider"],
+  projectName: string,
+): AgentSession {
+  return {
+    id,
+    provider,
+    source: "cli",
+    state: "active",
+    pid: null,
+    transcriptPath: null,
+    host,
+    workspace: { cwd: null, projectName },
+    activity: { startedAt: null, lastActivityAt: null },
+    focusTarget: { kind: "none" },
+  };
+}
+
+/** Two reachable hosts with sessions and one unreachable host; all names are synthetic. */
+function agentSessionsHostsScenario(now: Date): ProofScenario {
+  const base = defaultScenario(now);
+  return {
+    ...base,
+    name: "agent-sessions-hosts",
+    settings: { ...base.settings, agentSessionsEnabled: true, agentSessionsLocalOnly: false },
+    agentSessions: {
+      status: "hosts",
+      hosts: [
+        {
+          host: "WORKSTATION-A",
+          sessions: [
+            proofAgentSession("proof-1", "WORKSTATION-A", "codex", "example-project"),
+            proofAgentSession("proof-2", "WORKSTATION-A", "claude", "example-notes"),
+          ],
+          error: null,
+        },
+        {
+          host: "BUILD-BOX",
+          sessions: [proofAgentSession("proof-3", "BUILD-BOX", "claude", "example-ci")],
+          error: null,
+        },
+        { host: "LAB-HOST", sessions: [], error: "ssh: connection timed out" },
+      ],
+    },
+  };
+}
+
 const BUILDERS: Record<ProofScenarioName, (now: Date) => ProofScenario> = {
   default: defaultScenario,
   "two-codex-accounts": twoCodexAccountsScenario,
@@ -1175,6 +1229,7 @@ const BUILDERS: Record<ProofScenarioName, (now: Date) => ProofScenario> = {
   vercel: vercelScenario,
   "vercel-team-id-invalid": vercelTeamIdInvalidScenario,
   "kimi-bonus-credits": kimiBonusCreditsScenario,
+  "agent-sessions-hosts": agentSessionsHostsScenario,
 };
 
 export function isProofScenarioName(value: string): value is ProofScenarioName {
diff --git a/apps/desktop-tauri/src/proof/router.ts b/apps/desktop-tauri/src/proof/router.ts
index 910a75b996..591a3d9eeb 100644
--- a/apps/desktop-tauri/src/proof/router.ts
+++ b/apps/desktop-tauri/src/proof/router.ts
@@ -5,6 +5,7 @@ import type {
   CurrentSurfaceState,
   HttpServerConfig,
   HttpServerSnapshot,
+  SessionFocusResult,
   SettingsSnapshot,
   SettingsUpdate,
   TokenAccountBridge,
@@ -59,7 +60,6 @@ export const INERT_ACTIONS = [
   "codex_account_switch",
   "download_update",
   "export_preferences",
-  "focus_agent_session",
   "get_openai_live_usage",
   "get_openai_org_rate_limits",
   "grok_account_add",
@@ -424,7 +424,8 @@ export function createProofRouter(
     },
     grok_accounts_list: () => [],
     get_hooks_config: proofHooksConfig,
-    list_agent_sessions: () => ({ status: "disabled" }),
+    list_agent_sessions: () => scenario.agentSessions ?? { status: "disabled" },
+    focus_agent_session: (): SessionFocusResult => ({ status: "focused" }),
     get_gemini_cli_signed_in: () => ({ signedIn: true, credentialsPath: null }),
     get_vertexai_status: () => ({ hasCredentials: false, credentialsPath: null }),
     list_jetbrains_detected_ides: () => [],
diff --git a/apps/desktop-tauri/src/styles/parity-overrides.css b/apps/desktop-tauri/src/styles/parity-overrides.css
index 82d63f6e1f..9eceb824f7 100644
--- a/apps/desktop-tauri/src/styles/parity-overrides.css
+++ b/apps/desktop-tauri/src/styles/parity-overrides.css
@@ -321,6 +321,20 @@
   color: var(--provider-status-error);
 }
 
+.agent-sessions__host {
+  display: grid;
+  gap: 6px;
+}
+
+.agent-sessions__host-header {
+  font-weight: 600;
+  opacity: 0.8;
+}
+
+.agent-sessions__host-header--unreachable {
+  color: var(--provider-status-error);
+}
+
 /* ── Per-provider accent color override (#2972) ─────────────────── */
 .provider-detail-accent-color {
   margin-top: 16px;
diff --git a/rust/src/locale.rs b/rust/src/locale.rs
index 549b474e91..c3d5a06e50 100644
--- a/rust/src/locale.rs
+++ b/rust/src/locale.rs
@@ -999,6 +999,7 @@ locale_keys! {
     AgentSessionsSshHostsHelper,
     AgentSessionsLoading,
     AgentSessionsEmpty,
+    AgentSessionsHostUnreachable,
     UpdatesTitle,
     AboutBuilt,
     SectionLinks,
diff --git a/rust/src/locale/en-US.ftl b/rust/src/locale/en-US.ftl
index d1c724b93a..170e2e376f 100644
--- a/rust/src/locale/en-US.ftl
+++ b/rust/src/locale/en-US.ftl
@@ -565,6 +565,7 @@ AgentSessionsSshHostsLabel = Additional SSH hosts
 AgentSessionsSshHostsHelper = Comma-separated SSH targets. Connections use non-interactive mode and short timeouts.
 AgentSessionsLoading = Looking for agent sessions...
 AgentSessionsEmpty = No active agent sessions.
+AgentSessionsHostUnreachable = unreachable
 UpdatesTitle = Updates
 AboutBuilt = Built { "{}" }
 SectionLinks = Links
diff --git a/rust/src/locale/es-MX.ftl b/rust/src/locale/es-MX.ftl
index 67b3e9daa4..884e3392be 100644
--- a/rust/src/locale/es-MX.ftl
+++ b/rust/src/locale/es-MX.ftl
@@ -533,6 +533,7 @@ AgentSessionsSshHostsLabel = Hosts SSH
 AgentSessionsSshHostsHelper = Destinos SSH separados por comas. Las conexiones usan modo no interactivo y tiempos de espera cortos.
 AgentSessionsLoading = Buscando sesiones de agentes...
 AgentSessionsEmpty = No hay sesiones de agentes activas.
+AgentSessionsHostUnreachable = inaccesible
 UpdatesTitle = Actualizaciones
 AboutBuilt = Compilado el { "{}" }
 SectionLinks = Enlaces
diff --git a/rust/src/locale/ja-JP.ftl b/rust/src/locale/ja-JP.ftl
index dac8b77dfb..b3b60a6db1 100644
--- a/rust/src/locale/ja-JP.ftl
+++ b/rust/src/locale/ja-JP.ftl
@@ -533,6 +533,7 @@ AgentSessionsSshHostsLabel = SSH ホスト
 AgentSessionsSshHostsHelper = カンマ区切りの SSH ターゲット。接続は非対話モード・短いタイムアウトを使用。
 AgentSessionsLoading = エージェントセッションを検索中…
 AgentSessionsEmpty = アクティブなエージェントセッションはありません。
+AgentSessionsHostUnreachable = 接続できません
 UpdatesTitle = アップデート
 AboutBuilt = ビルド日 { "{}" }
 SectionLinks = リンク
diff --git a/rust/src/locale/ko-KR.ftl b/rust/src/locale/ko-KR.ftl
index 144ab686a4..3be7e11dad 100644
--- a/rust/src/locale/ko-KR.ftl
+++ b/rust/src/locale/ko-KR.ftl
@@ -533,6 +533,7 @@ AgentSessionsSshHostsLabel = SSH 호스트
 AgentSessionsSshHostsHelper = 쉼표로 구분된 SSH 대상입니다. 연결은 비대화형 모드와 짧은 제한 시간을 사용합니다.
 AgentSessionsLoading = 에이전트 세션을 찾는 중...
 AgentSessionsEmpty = 활성 에이전트 세션이 없습니다.
+AgentSessionsHostUnreachable = 연결할 수 없음
 UpdatesTitle = 업데이트
 AboutBuilt = 빌드 날짜 { "{}" }
 SectionLinks = 링크
diff --git a/rust/src/locale/pt-BR.ftl b/rust/src/locale/pt-BR.ftl
index 8d98f53549..67789ac1d1 100644
--- a/rust/src/locale/pt-BR.ftl
+++ b/rust/src/locale/pt-BR.ftl
@@ -552,6 +552,7 @@ AgentSessionsSshHostsLabel = Hosts SSH
 AgentSessionsSshHostsHelper = Destinos SSH separados por vírgula. As conexões usam modo não interativo e tempos limites curtos.
 AgentSessionsLoading = Procurando sessões de agente...
 AgentSessionsEmpty = Nenhuma sessão de agente ativa.
+AgentSessionsHostUnreachable = inacessível
 UpdatesTitle = Atualizações
 AboutBuilt = Compilado em { "{}" }
 SectionLinks = Links
diff --git a/rust/src/locale/ru-RU.ftl b/rust/src/locale/ru-RU.ftl
index aca02c77ab..fa030fbd50 100644
--- a/rust/src/locale/ru-RU.ftl
+++ b/rust/src/locale/ru-RU.ftl
@@ -565,6 +565,7 @@ AgentSessionsSshHostsLabel = SSH-хосты
 AgentSessionsSshHostsHelper = Цели SSH, разделенные запятыми. Соединения используют неинтерактивный режим и короткие таймауты.
 AgentSessionsLoading = Ищу агентские сессии...
 AgentSessionsEmpty = Нет сеансов активных агентов.
+AgentSessionsHostUnreachable = недоступен
 UpdatesTitle = Обновления
 AboutBuilt = Сборка от { "{}" }
 SectionLinks = Ссылки
diff --git a/rust/src/locale/tr-TR.ftl b/rust/src/locale/tr-TR.ftl
index 872146dc7c..28db3139e0 100644
--- a/rust/src/locale/tr-TR.ftl
+++ b/rust/src/locale/tr-TR.ftl
@@ -565,6 +565,7 @@ AgentSessionsSshHostsLabel = SSH sunucuları
 AgentSessionsSshHostsHelper = Virgülle ayrılmış SSH hedefleri. Bağlantılar etkileşimsiz modu ve kısa zaman aşımlarını kullanır.
 AgentSessionsLoading = Aracı oturumları aranıyor...
 AgentSessionsEmpty = Etkin aracı oturumu yok.
+AgentSessionsHostUnreachable = ulaşılamıyor
 UpdatesTitle = Güncellemeler
 AboutBuilt = Derleme tarihi { "{}" }
 SectionLinks = Bağlantılar
diff --git a/rust/src/locale/uk-UA.ftl b/rust/src/locale/uk-UA.ftl
index 32ec3505db..b344d6261d 100644
--- a/rust/src/locale/uk-UA.ftl
+++ b/rust/src/locale/uk-UA.ftl
@@ -565,6 +565,7 @@ AgentSessionsSshHostsLabel = SSH-хости
 AgentSessionsSshHostsHelper = SSH-адреси через кому. З’єднання працюють у неінтерактивному режимі з короткими тайм-аутами.
 AgentSessionsLoading = Пошук сеансів агентів...
 AgentSessionsEmpty = Немає активних сеансів агентів.
+AgentSessionsHostUnreachable = недоступний
 UpdatesTitle = Оновлення
 AboutBuilt = Збірка від { "{}" }
 SectionLinks = Посилання
diff --git a/rust/src/locale/zh-CN.ftl b/rust/src/locale/zh-CN.ftl
index 7cc45acb64..fae6c91936 100644
--- a/rust/src/locale/zh-CN.ftl
+++ b/rust/src/locale/zh-CN.ftl
@@ -533,6 +533,7 @@ AgentSessionsSshHostsLabel = SSH 主机
 AgentSessionsSshHostsHelper = 以逗号分隔的 SSH 目标。连接使用非交互模式和短超时。
 AgentSessionsLoading = 正在查找 Agent 会话…
 AgentSessionsEmpty = 没有活跃的 Agent 会话。
+AgentSessionsHostUnreachable = 无法连接
 UpdatesTitle = 更新
 AboutBuilt = 构建于 { "{}" }
 SectionLinks = 链接
diff --git a/rust/src/locale/zh-TW.ftl b/rust/src/locale/zh-TW.ftl
index 97caa0fdab..497f9f5686 100644
--- a/rust/src/locale/zh-TW.ftl
+++ b/rust/src/locale/zh-TW.ftl
@@ -533,6 +533,7 @@ AgentSessionsSshHostsLabel = SSH 主機
 AgentSessionsSshHostsHelper = 以逗號分隔的 SSH 目標。連線使用非互動模式和短逾時。
 AgentSessionsLoading = 正在查找 Agent 工作階段…
 AgentSessionsEmpty = 沒有活躍的 Agent 工作階段。
+AgentSessionsHostUnreachable = 無法連線
 UpdatesTitle = 更新
 AboutBuilt = 建置於 { "{}" }
 SectionLinks = 連結