fix: add inline clear action to conversation search

Show a clear button when the conversation search contains text. Clearing restores the scoped conversation list and returns focus to the input, with regression coverage for visibility and filtering.

Release note: Conversation search now includes an X button to clear keywords and return to the current project's conversations.

src/renderer/src/App.test.tsx

@@ -2183,6 +2183,10 @@ describe("App", () => {
     ]);
     const { container } = render(<App />);
     const search = await screen.findByLabelText("搜索对话");
+    const searchControls = within(search.parentElement!);
+    expect(
+      searchControls.queryByRole("button", { name: "清除搜索" }),
+    ).not.toBeInTheDocument();
     const conversationList =
       container.querySelector<HTMLElement>(".conversation-list");
     if (!conversationList) {
@@ -2219,6 +2223,33 @@ describe("App", () => {
       ).not.toBeInTheDocument();
     });
 
+    const clearSearch = searchControls.getByRole("button", {
+      name: "清除搜索",
+    });
+    clearSearch.focus();
+    fireEvent.click(clearSearch);
+    expect(search).toHaveValue("");
+    expect(search).toHaveFocus();
+    expect(
+      searchControls.queryByRole("button", { name: "清除搜索" }),
+    ).not.toBeInTheDocument();
+    await waitFor(() => {
+      expect(
+        within(conversationList).getByText("标题里的 Alpha"),
+      ).toBeInTheDocument();
+      expect(
+        within(conversationList).getByText("正文命中的会话"),
+      ).toBeInTheDocument();
+      expect(
+        within(conversationList).queryByText("其他项目里的 Alpha"),
+      ).not.toBeInTheDocument();
+    });
+    fireEvent.change(search, { target: { value: "   " } });
+    fireEvent.click(
+      searchControls.getByRole("button", { name: "清除搜索" }),
+    );
+    expect(search).toHaveValue("");
+
     fireEvent.change(search, { target: { value: "missing topic" } });
     expect(
       await within(conversationList).findByText("没有匹配的对话"),

src/renderer/src/App.tsx

@@ -2448,6 +2448,7 @@ function App(): React.JSX.Element {
   ] = useState(true);
   const [incompleteMagicTodoCount, setIncompleteMagicTodoCount] = useState(0);
   const [searchQuery, setSearchQuery] = useState("");
+  const searchInputRef = useRef<HTMLInputElement>(null);
   const deferredSearchQuery = useDeferredValue(searchQuery);
   const [searchConversationSnapshot, setSearchConversationSnapshot] =
     useState(conversations);
@@ -8181,10 +8182,25 @@ function App(): React.JSX.Element {
           <Search size={15} />
           <input
             aria-label={t("sidebar.searchLabel")}
+            ref={searchInputRef}
             onChange={(event) => setSearchQuery(event.target.value)}
             placeholder={t("sidebar.searchPlaceholder")}
             value={searchQuery}
           />
+          {searchQuery.length > 0 && (
+            <button
+              aria-label={t("conversation.clearSearch")}
+              className="icon-button sidebar-search__clear"
+              onClick={() => {
+                setSearchQuery("");
+                searchInputRef.current?.focus();
+              }}
+              title={t("conversation.clearSearch")}
+              type="button"
+            >
+              <X aria-hidden="true" size={14} />
+            </button>
+          )}
         </div>
 
         <nav className="primary-nav" aria-label={t("navigation.label")}>

src/renderer/src/styles.css

@@ -3373,10 +3373,12 @@ textarea:focus-visible {
 }
 
 .sidebar-search {
+  position: relative;
   display: flex;
   min-width: 248px;
   align-items: center;
   padding: 9px 11px;
+  padding-right: 40px;
   border: 1px solid var(--border-default);
   border-radius: var(--radius-control);
   margin-bottom: 15px;
@@ -3386,6 +3388,7 @@ textarea:focus-visible {
 }
 
 .sidebar-search input {
+  min-width: 0;
   width: 100%;
   border: 0;
   outline: 0;
@@ -3398,6 +3401,19 @@ textarea:focus-visible {
   color: var(--text-muted);
 }
 
+.sidebar-search > svg {
+  flex-shrink: 0;
+}
+
+.sidebar-search .sidebar-search__clear {
+  position: absolute;
+  top: 50%;
+  right: var(--space-2);
+  width: 24px;
+  height: 24px;
+  transform: translateY(-50%);
+}
+
 .primary-nav {
   display: flex;
   min-width: 248px;