diff --git a/apps/web/src/components/session-card.tsx b/apps/web/src/components/session-card.tsx
index 00aa0c3..b2ac9dc 100644
--- a/apps/web/src/components/session-card.tsx
+++ b/apps/web/src/components/session-card.tsx
@@ -75,7 +75,12 @@ export function SessionCard({
   const isActive = ["running", "building", "starting", "probing", "pending", "unhealthy"].includes(session.status);
 
   return (
-    <article className="card session-card">
+    <article className={`card session-card ${isBusy ? "busy" : ""}`}>
+      {isBusy && (
+        <div className="session-busy-overlay">
+          <Icon name="loading" size="md" />
+        </div>
+      )}
       <div className="session-card-content">
         <div className="session-card-header">
           <div className="session-card-title">
diff --git a/apps/web/src/pages/dashboard.tsx b/apps/web/src/pages/dashboard.tsx
index 3071d1f..1b6d99e 100644
--- a/apps/web/src/pages/dashboard.tsx
+++ b/apps/web/src/pages/dashboard.tsx
@@ -143,6 +143,7 @@ export const HomePage = () => {
   };
 
   const handleStop = async (session: SessionView) => {
+    if (actionBusy === session.id) return;
     setActionBusy(session.id);
     try {
       await stopInstance(session.project_id, session.repository_id, session.id);
@@ -153,6 +154,7 @@ export const HomePage = () => {
   };
 
   const handleDelete = async (session: SessionView) => {
+    if (actionBusy === session.id) return;
     setActionBusy(session.id);
     try {
       await deleteInstance(session.project_id, session.repository_id, session.id);
@@ -165,6 +167,7 @@ export const HomePage = () => {
   };
 
   const handleRecreateTunnel = async (session: SessionView) => {
+    if (actionBusy === session.id) return;
     setActionBusy(session.id);
     try {
       await recreateInstanceTunnel(session.project_id, session.repository_id, session.id);
@@ -175,6 +178,7 @@ export const HomePage = () => {
   };
 
   const handleStart = async (session: SessionView) => {
+    if (actionBusy === session.id) return;
     setActionBusy(session.id);
     try {
       await startInstance(session.project_id, session.repository_id, session.id);
diff --git a/apps/web/src/pages/sessions.tsx b/apps/web/src/pages/sessions.tsx
index 11dba2a..22ac603 100644
--- a/apps/web/src/pages/sessions.tsx
+++ b/apps/web/src/pages/sessions.tsx
@@ -9,6 +9,7 @@ import {
   type Session,
   deleteInstance,
   stopInstance,
+  startInstance,
   checkInstanceHealth,
   recreateInstanceTunnel,
 } from "../api/sessions";
@@ -38,7 +39,6 @@ export const SessionsPage = () => {
 
   const [tunnelHealth, setTunnelHealth] = useState<Record<string, InstanceHealth>>({});
   const [loadingSessionId, setLoadingSessionId] = useState<string | null>(null);
-  const [loadingAction, setLoadingAction] = useState<string>("");
 
   const loadSessions = useCallback(async () => {
     setStatus("loading");
@@ -155,8 +155,8 @@ export const SessionsPage = () => {
   };
 
   const handleStop = async (session: Session) => {
+    if (loadingSessionId === session.id) return;
     setLoadingSessionId(session.id);
-    setLoadingAction("Stopping...");
     try {
       await stopInstance(session.project_id, session.repository_id, session.id);
       await loadSessions();
@@ -164,13 +164,12 @@ export const SessionsPage = () => {
       // ignore
     } finally {
       setLoadingSessionId(null);
-      setLoadingAction("");
     }
   };
 
   const handleDelete = async (session: Session) => {
+    if (loadingSessionId === session.id) return;
     setLoadingSessionId(session.id);
-    setLoadingAction("Deleting...");
     try {
       await deleteInstance(session.project_id, session.repository_id, session.id);
       setDirtyDeleteSession(null);
@@ -189,13 +188,12 @@ export const SessionsPage = () => {
       }
     } finally {
       setLoadingSessionId(null);
-      setLoadingAction("");
     }
   };
 
   const handleForceDelete = async (session: Session) => {
+    if (loadingSessionId === session.id) return;
     setLoadingSessionId(session.id);
-    setLoadingAction("Force deleting...");
     try {
       await deleteInstance(session.project_id, session.repository_id, session.id, true);
       setDirtyDeleteSession(null);
@@ -205,13 +203,12 @@ export const SessionsPage = () => {
       // ignore
     } finally {
       setLoadingSessionId(null);
-      setLoadingAction("");
     }
   };
 
   const handleRecreateTunnel = async (session: Session) => {
+    if (loadingSessionId === session.id) return;
     setLoadingSessionId(session.id);
-    setLoadingAction("Recreating tunnel...");
     try {
       await recreateInstanceTunnel(
         session.project_id,
@@ -224,7 +221,19 @@ export const SessionsPage = () => {
       // ignore
     } finally {
       setLoadingSessionId(null);
-      setLoadingAction("");
+    }
+  };
+
+  const handleStart = async (session: Session) => {
+    if (loadingSessionId === session.id) return;
+    setLoadingSessionId(session.id);
+    try {
+      await startInstance(session.project_id, session.repository_id, session.id);
+      await loadSessions();
+    } catch {
+      // ignore
+    } finally {
+      setLoadingSessionId(null);
     }
   };
 
@@ -273,18 +282,11 @@ export const SessionsPage = () => {
           )}
 
           {/* Session List */}
-          <div className={`sessions-list-wrapper ${loadingSessionId ? "dimmed" : ""}`}>
-            {loadingSessionId && (
-              <div className="loading-overlay">
-                <div className="loading-content">
-                  <Icon name="loading" size="lg" />
-                  <p>{loadingAction}</p>
-                </div>
-              </div>
-            )}
+          <div className="sessions-list-wrapper">
             <SessionList
               sessions={sessions}
               onOpen={handleOpen}
+              onStart={handleStart}
               onStop={handleStop}
               onDelete={handleDelete}
               onRecreateTunnel={handleRecreateTunnel}
diff --git a/apps/web/src/styles.css b/apps/web/src/styles.css
index 721055b..baccc9d 100644
--- a/apps/web/src/styles.css
+++ b/apps/web/src/styles.css
@@ -2500,6 +2500,25 @@ a.nav-item,
   color: var(--muted);
 }
 
+.session-card {
+  position: relative;
+}
+
+.session-card.busy {
+  opacity: 0.7;
+}
+
+.session-busy-overlay {
+  position: absolute;
+  inset: 0;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  background: rgba(var(--bg-rgb, 255, 255, 255), 0.8);
+  border-radius: var(--space-2);
+  z-index: 1;
+}
+
 /* ============================================
    Terminal Styles
    ============================================ */