feat: add conversation selection mode and swipe tabs

tests/conversation-home-items.test.ts

@@ -168,4 +168,34 @@ test("conversation items expose context status while keeping idle activity silen
   assert.equal(threadConversation.contextBudgetIndicator.level, "urgent");
   assert.equal(threadConversation.activityIconCount, 0);
   assert.equal(masterAgent.activityIconCount, 0);
+  assert.equal(masterAgent.contextBudgetIndicator.visible, true);
+  assert.equal(masterAgent.contextBudgetIndicator.percent, 100);
+  assert.equal(masterAgent.contextBudgetIndicator.level, "safe");
+});
+
+test("conversation items keep a safe context ring even when no thread snapshot exists", async () => {
+  await setup();
+  const state = await readState();
+
+  state.projects = state.projects.filter((project) => project.id === "master-agent");
+  state.projects.push(
+    buildImportedThreadProject(
+      "mac-studio",
+      "single-thread-no-context",
+      "Talking",
+      "talking",
+      "调试回归",
+      "thread-no-context",
+      "2026-03-30T11:20:00+08:00",
+    ),
+  );
+  state.threadContextSnapshots = [];
+
+  const items = getConversationHomeItems(state);
+  const directThread = items.find((item) => item.projectId === "single-thread-no-context");
+
+  assert.ok(directThread);
+  assert.equal(directThread?.contextBudgetIndicator.visible, true);
+  assert.equal(directThread?.contextBudgetIndicator.percent, 100);
+  assert.equal(directThread?.contextBudgetIndicator.level, "safe");
 });