feat: update session resume UI to show most recent prompt first

Session list now sorts by last_activity_at descending so the most
recently used session appears at the top. Preview text now shows the
most recent user message rather than the first few messages, giving a
much more relevant glimpse of where each session left off.

src/lib/stores/sessions.test.ts

@@ -59,12 +59,52 @@ const makeConversation = () => ({
 
 describe("sessionsStore - loadSessions", () => {
   it("loads sessions from backend and updates the store", async () => {
-    const sessionList = [{ id: "session-1", name: "Test", message_count: 1, preview: "..." }];
+    const sessionList = [
+      {
+        id: "session-1",
+        name: "Test",
+        message_count: 1,
+        preview: "...",
+        last_activity_at: "2026-03-03T11:00:00.000Z",
+      },
+    ];
     setMockInvokeResult("list_sessions", sessionList);
     await sessionsStore.loadSessions();
     expect(get(sessionsStore.sessions)).toEqual(sessionList);
   });
 
+  it("sorts sessions by last_activity_at descending", async () => {
+    const sessionList = [
+      {
+        id: "older",
+        name: "Older",
+        message_count: 1,
+        preview: "...",
+        last_activity_at: "2026-03-01T10:00:00.000Z",
+      },
+      {
+        id: "newest",
+        name: "Newest",
+        message_count: 1,
+        preview: "...",
+        last_activity_at: "2026-03-03T12:00:00.000Z",
+      },
+      {
+        id: "middle",
+        name: "Middle",
+        message_count: 1,
+        preview: "...",
+        last_activity_at: "2026-03-02T10:00:00.000Z",
+      },
+    ];
+    setMockInvokeResult("list_sessions", sessionList);
+    await sessionsStore.loadSessions();
+    const sorted = get(sessionsStore.sessions);
+    expect(sorted[0].id).toBe("newest");
+    expect(sorted[1].id).toBe("middle");
+    expect(sorted[2].id).toBe("older");
+  });
+
   it("handles errors gracefully", async () => {
     const spy = vi.spyOn(console, "error").mockImplementation(() => {});
     setMockInvokeResult("list_sessions", new Error("Backend error"));
@@ -128,12 +168,44 @@ describe("sessionsStore - searchSessions", () => {
   });
 
   it("searches with the given query", async () => {
-    const results = [{ id: "session-1", name: "Test", message_count: 1, preview: "..." }];
+    const results = [
+      {
+        id: "session-1",
+        name: "Test",
+        message_count: 1,
+        preview: "...",
+        last_activity_at: "2026-03-03T11:00:00.000Z",
+      },
+    ];
     setMockInvokeResult("search_sessions", results);
     await sessionsStore.searchSessions("test");
     expect(get(sessionsStore.sessions)).toEqual(results);
   });
 
+  it("sorts search results by last_activity_at descending", async () => {
+    const results = [
+      {
+        id: "older",
+        name: "Older",
+        message_count: 1,
+        preview: "...",
+        last_activity_at: "2026-03-01T10:00:00.000Z",
+      },
+      {
+        id: "newest",
+        name: "Newest",
+        message_count: 1,
+        preview: "...",
+        last_activity_at: "2026-03-03T12:00:00.000Z",
+      },
+    ];
+    setMockInvokeResult("search_sessions", results);
+    await sessionsStore.searchSessions("query");
+    const sorted = get(sessionsStore.sessions);
+    expect(sorted[0].id).toBe("newest");
+    expect(sorted[1].id).toBe("older");
+  });
+
   it("updates searchQuery store", async () => {
     setMockInvokeResult("search_sessions", []);
     await sessionsStore.searchSessions("hello");
@@ -187,6 +259,94 @@ describe("sessionsStore - saveConversation", () => {
     const conv = { ...makeConversation(), terminalLines: [] };
     await sessionsStore.saveConversation(conv as never);
   });
+
+  it("uses the most recent user message as the preview", async () => {
+    const { invoke } = await import("@tauri-apps/api/core");
+    setMockInvokeResult("save_session", undefined);
+    setMockInvokeResult("list_sessions", []);
+
+    const conv = {
+      ...makeConversation(),
+      terminalLines: [
+        {
+          id: "1",
+          type: "user",
+          content: "First message",
+          timestamp: new Date(),
+          toolName: undefined,
+        },
+        {
+          id: "2",
+          type: "assistant",
+          content: "Reply one",
+          timestamp: new Date(),
+          toolName: undefined,
+        },
+        {
+          id: "3",
+          type: "user",
+          content: "Most recent prompt",
+          timestamp: new Date(),
+          toolName: undefined,
+        },
+        {
+          id: "4",
+          type: "assistant",
+          content: "Reply two",
+          timestamp: new Date(),
+          toolName: undefined,
+        },
+      ],
+    };
+    await sessionsStore.saveConversation(conv as never);
+
+    const saveCall = vi.mocked(invoke).mock.calls.find((call) => call[0] === "save_session");
+    const capturedSession = (saveCall![1] as { session: SavedSession }).session;
+    expect(capturedSession.preview).toBe("Most recent prompt");
+  });
+
+  it("truncates long preview text at 150 characters", async () => {
+    const { invoke } = await import("@tauri-apps/api/core");
+    setMockInvokeResult("save_session", undefined);
+    setMockInvokeResult("list_sessions", []);
+
+    const longContent = "A".repeat(200);
+    const conv = {
+      ...makeConversation(),
+      terminalLines: [
+        { id: "1", type: "user", content: longContent, timestamp: new Date(), toolName: undefined },
+      ],
+    };
+    await sessionsStore.saveConversation(conv as never);
+
+    const saveCall = vi.mocked(invoke).mock.calls.find((call) => call[0] === "save_session");
+    const capturedSession = (saveCall![1] as { session: SavedSession }).session;
+    expect(capturedSession.preview).toBe("A".repeat(150) + "...");
+  });
+
+  it("uses 'Empty conversation' as preview when there are no user messages", async () => {
+    const { invoke } = await import("@tauri-apps/api/core");
+    setMockInvokeResult("save_session", undefined);
+    setMockInvokeResult("list_sessions", []);
+
+    const conv = {
+      ...makeConversation(),
+      terminalLines: [
+        {
+          id: "1",
+          type: "assistant",
+          content: "Only assistant message",
+          timestamp: new Date(),
+          toolName: undefined,
+        },
+      ],
+    };
+    await sessionsStore.saveConversation(conv as never);
+
+    const saveCall = vi.mocked(invoke).mock.calls.find((call) => call[0] === "save_session");
+    const capturedSession = (saveCall![1] as { session: SavedSession }).session;
+    expect(capturedSession.preview).toBe("Empty conversation");
+  });
 });
 
 describe("sessionsStore - scheduleAutoSave and cancelAutoSave", () => {

src/lib/stores/sessions.ts

@@ -378,7 +378,11 @@ function createSessionsStore() {
     isLoading.set(true);
     try {
       const result = await invoke<SessionListItem[]>("list_sessions");
-      sessions.set(result);
+      sessions.set(
+        result.sort(
+          (a, b) => new Date(b.last_activity_at).getTime() - new Date(a.last_activity_at).getTime()
+        )
+      );
     } catch (error) {
       console.error("Failed to load sessions:", error);
     } finally {
@@ -395,15 +399,13 @@ function createSessionsStore() {
       tool_name: line.toolName,
     }));
 
-    const userAndAssistantMessages = conversation.terminalLines.filter(
+    const userMessages = conversation.terminalLines.filter((line) => line.type === "user");
-      (line) => line.type === "user" || line.type === "assistant"
+    const mostRecentUserMessage = userMessages.at(-1);
-    );
+    const previewContent = mostRecentUserMessage
-    const previewContent =
+      ? mostRecentUserMessage.content.length > 150
-      userAndAssistantMessages
+        ? mostRecentUserMessage.content.slice(0, 150) + "..."
-        .slice(0, 3)
+        : mostRecentUserMessage.content
-        .map((m) => m.content)
+      : "Empty conversation";
-        .join(" ")
-        .slice(0, 150) + (userAndAssistantMessages.length > 3 ? "..." : "");
 
     const session: SavedSession = {
       id: conversation.id,
@@ -458,7 +460,11 @@ function createSessionsStore() {
       const result = await invoke<SessionListItem[]>("search_sessions", {
         query,
       });
-      sessions.set(result);
+      sessions.set(
+        result.sort(
+          (a, b) => new Date(b.last_activity_at).getTime() - new Date(a.last_activity_at).getTime()
+        )
+      );
     } catch (error) {
       console.error("Failed to search sessions:", error);
     } finally {