diff --git a/frontend/agenda-session-launcher.js b/frontend/agenda-session-launcher.js
new file mode 100644
index 0000000..76c17e3
--- /dev/null
+++ b/frontend/agenda-session-launcher.js
@@ -0,0 +1,33 @@
+(function (root, factory) {
+  if (typeof module === 'object' && module.exports) module.exports = factory;
+  else root.createAgendaSessionLauncher = factory;
+})(typeof self !== 'undefined' ? self : this, function createAgendaSessionLauncher(options) {
+  let pending = null;
+
+  function open() {
+    if (pending) return pending;
+    options.selectAgenda();
+    pending = Promise.resolve()
+      .then(() => options.discover())
+      .then(complete => {
+        if (!options.isAgendaSelected()) return 'cancelled';
+        if (complete === false || options.hasMore()) {
+          options.announce('Agenda check paused. Retry to check older assigned deadlines.');
+          return 'incomplete';
+        }
+        const opened = options.hasCheckpoint() ? options.resume() : options.start();
+        if (!opened) options.announce('No deadlines are ready in Agenda.');
+        return opened ? 'opened' : 'empty';
+      })
+      .catch(() => {
+        if (options.isAgendaSelected()) {
+          options.announce('Agenda check paused. Retry to check older assigned deadlines.');
+        }
+        return 'incomplete';
+      })
+      .finally(() => { pending = null; });
+    return pending;
+  }
+
+  return {open};
+});
diff --git a/frontend/dashboard.js b/frontend/dashboard.js
index cb2b311..167b4af 100644
--- a/frontend/dashboard.js
+++ b/frontend/dashboard.js
@@ -1210,11 +1210,18 @@
     qs('[data-work-filter="today"]').click();
   }
 
+  const agendaSessionLauncher = createAgendaSessionLauncher({
+    selectAgenda: () => selectMobileQueue('agenda'),
+    discover: completeAgendaIssues,
+    isAgendaSelected: () => selectedWorkFilter === 'agenda',
+    hasMore: () => Boolean(workPagination.issue?.has_more),
+    hasCheckpoint: () => Boolean(agendaSessionCheckpoint.read()),
+    resume: () => workSession.resume(),
+    start: () => workSession.start(),
+    announce: message => { qs('#my-work-action-status').textContent = message; },
+  });
   function openAgendaSession() {
-    selectMobileQueue('agenda');
-    const opened = agendaSessionCheckpoint.read() ? workSession.resume() : workSession.start();
-    if (!opened) qs('#my-work-action-status').textContent = 'No deadlines are ready in Agenda.';
-    return opened ? 'opened' : 'empty';
+    return agendaSessionLauncher.open();
   }
 
   let todayReadinessTrigger = null;
@@ -2340,17 +2347,20 @@
   }
 
   async function completeAgendaIssues() {
-    if (selectedWorkFilter !== 'agenda' || !workPagination.issue?.has_more || !lastContextSnapshot) return;
+    if (selectedWorkFilter !== 'agenda') return false;
+    if (!workPagination.issue?.has_more) return true;
+    if (!lastContextSnapshot) return false;
     agendaChecking = true;
     qs('#my-work-action-status').textContent = 'Checking all assigned deadlines…';
     renderMyWork();
     const complete = await workPager.loadAll('issue', () => lastContextSnapshot?.issues || []);
     agendaChecking = false;
-    if (selectedWorkFilter !== 'agenda') return;
+    if (selectedWorkFilter !== 'agenda') return false;
     qs('#my-work-action-status').textContent = complete ?
       'All assigned deadlines checked.' :
       'Agenda check paused. Retry to check older assigned deadlines.';
     renderMyWork();
+    return complete && !workPagination.issue?.has_more;
   }
 
   function renderDrafts() {
diff --git a/frontend/index.html b/frontend/index.html
index e663395..1d9f5cf 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -1055,6 +1055,7 @@
 <script src="static/mobile-task-dock.js"></script>
 <script src="static/mobile-work-entry.js"></script>
 <script src="static/mobile-queue-launcher.js"></script>
+<script src="static/agenda-session-launcher.js"></script>
 <script src="static/mobile-launch.js"></script>
 <script src="static/install-app.js"></script>
 <script src="static/mobile-device-setup.js"></script>
diff --git a/frontend/service-worker.js b/frontend/service-worker.js
index 2061ec2..b37330a 100644
--- a/frontend/service-worker.js
+++ b/frontend/service-worker.js
@@ -74,6 +74,7 @@ const SHELL = [
   BASE + 'static/mobile-task-dock.js',
   BASE + 'static/mobile-work-entry.js',
   BASE + 'static/mobile-queue-launcher.js',
+  BASE + 'static/agenda-session-launcher.js',
   BASE + 'static/mobile-launch.js',
   BASE + 'static/install-app.js',
   BASE + 'static/mobile-device-setup.js',
diff --git a/tests/test_my_work.py b/tests/test_my_work.py
index 8fdd5dc..a73c3b0 100644
--- a/tests/test_my_work.py
+++ b/tests/test_my_work.py
@@ -40,6 +40,89 @@ COMMENT_ACTIONS = Path(__file__).parents[1] / "frontend" / "comment-actions.js"
 PICK_WORK = Path(__file__).parents[1] / "frontend" / "pick-work.js"
 WORK_ROUTE = Path(__file__).parents[1] / "frontend" / "work-route.js"
 UPDATE_OWNERSHIP = Path(__file__).parents[1] / "frontend" / "update-ownership.js"
+AGENDA_SESSION_LAUNCHER = Path(__file__).parents[1] / "frontend" / "agenda-session-launcher.js"
+
+
+def test_agenda_session_launch_waits_for_complete_single_flight_discovery():
+    script = f"""
+const createLauncher = require({json.dumps(str(AGENDA_SESSION_LAUNCHER))});
+let finishDiscovery;
+let discoveries = 0;
+let opens = 0;
+let queue = 'agenda';
+const launcher = createLauncher({{
+  selectAgenda: () => {{ queue = 'agenda'; }},
+  discover: () => {{
+    discoveries += 1;
+    return new Promise(resolve => {{ finishDiscovery = resolve; }});
+  }},
+  isAgendaSelected: () => queue === 'agenda',
+  hasMore: () => false,
+  hasCheckpoint: () => true,
+  resume: () => {{ opens += 1; return true; }},
+  start: () => {{ throw new Error('must resume'); }},
+  announce: () => {{}},
+}});
+const first = launcher.open();
+const second = launcher.open();
+Promise.resolve().then(() => {{
+  const before = {{discoveries, opens, same:first === second}};
+  finishDiscovery(true);
+  return Promise.all([first, second]).then(results => {{
+    process.stdout.write(JSON.stringify({{before, results, discoveries, opens}}));
+  }});
+}});
+"""
+    result = subprocess.run(["node", "-e", script], capture_output=True, text=True)
+
+    assert result.returncode == 0, result.stderr
+    assert json.loads(result.stdout) == {
+        "before": {"discoveries": 1, "opens": 0, "same": True},
+        "results": ["opened", "opened"],
+        "discoveries": 1,
+        "opens": 1,
+    }
+
+
+def test_agenda_session_launch_preserves_progress_when_discovery_fails_or_queue_changes():
+    script = f"""
+const createLauncher = require({json.dumps(str(AGENDA_SESSION_LAUNCHER))});
+async function scenario(mode) {{
+  let queue = 'agenda';
+  let opens = 0;
+  const messages = [];
+  const launcher = createLauncher({{
+    selectAgenda: () => {{ queue = 'agenda'; }},
+    discover: async () => {{
+      if (mode === 'leave') queue = 'today';
+      if (mode === 'throw') throw new Error('offline');
+      return mode !== 'incomplete';
+    }},
+    isAgendaSelected: () => queue === 'agenda',
+    hasMore: () => mode === 'incomplete',
+    hasCheckpoint: () => true,
+    resume: () => {{ opens += 1; return true; }},
+    start: () => {{ opens += 1; return true; }},
+    announce: message => messages.push(message),
+  }});
+  return {{result:await launcher.open(), opens, messages}};
+}}
+Promise.all(['incomplete', 'throw', 'leave'].map(scenario)).then(results =>
+  process.stdout.write(JSON.stringify(results))
+);
+"""
+    result = subprocess.run(["node", "-e", script], capture_output=True, text=True)
+
+    assert result.returncode == 0, result.stderr
+    assert json.loads(result.stdout) == [
+        {"result": "incomplete", "opens": 0, "messages": [
+            "Agenda check paused. Retry to check older assigned deadlines."
+        ]},
+        {"result": "incomplete", "opens": 0, "messages": [
+            "Agenda check paused. Retry to check older assigned deadlines."
+        ]},
+        {"result": "cancelled", "opens": 0, "messages": []},
+    ]
 
 
 def test_protect_today_route_is_an_explicit_agenda_action():
@@ -305,7 +388,11 @@ process.stdout.write(JSON.stringify({{
 async def test_mobile_agenda_launcher_starts_or_resumes_the_durable_agenda_session():
     html = await dashboard()
 
+    assert '<script src="static/agenda-session-launcher.js"></script>' in html
     assert "openAgenda: openAgendaSession" in html
+    assert "const agendaSessionLauncher = createAgendaSessionLauncher({" in html
+    assert "discover: completeAgendaIssues" in html
+    assert "hasMore: () => Boolean(workPagination.issue?.has_more)" in html
     assert "key: 'stackchain.agenda-session.v1'" in html
     assert "checkpoint: () => selectedWorkFilter === 'agenda' ? agendaSessionCheckpoint : sessionCheckpoint" in html
     assert "checkpointEnabled: () => ['today', 'agenda'].includes(selectedWorkFilter)" in html
diff --git a/tests/test_service_worker.py b/tests/test_service_worker.py
index 6309b0c..a284c39 100644
--- a/tests/test_service_worker.py
+++ b/tests/test_service_worker.py
@@ -786,6 +786,7 @@ def test_install_precaches_complete_subpath_scoped_app_shell():
         "/dashboard/static/mobile-task-dock.js",
         "/dashboard/static/mobile-work-entry.js",
         "/dashboard/static/mobile-queue-launcher.js",
+        "/dashboard/static/agenda-session-launcher.js",
         "/dashboard/static/mobile-launch.js",
         "/dashboard/static/install-app.js",
         "/dashboard/static/mobile-device-setup.js",