diff --git a/src/client/src/controllers/sessionController.ts b/src/client/src/controllers/sessionController.ts
index f55b04c..4fd3dfc 100644
--- a/src/client/src/controllers/sessionController.ts
+++ b/src/client/src/controllers/sessionController.ts
@@ -6,6 +6,7 @@ import { readChatHistoryCache, mergeChatHistory, writeChatHistoryCache, type Raw
 import { applyTranscriptEvent } from "../chatTranscript";
 import { isShellInput } from "../inputModes";
 import { GlobalSessionSocket, SessionSocket, type SessionUiEvent } from "../sessionSocket";
+import { markSessionArchived, selectionAfterArchivingSession } from "./sessionSelection";
 import type { GetState, SetState, UpdateUrl } from "./types";
 
 export class SessionController {
@@ -158,10 +159,15 @@ export class SessionController {
     if (!session) return;
     try {
       await api.archive(session.id);
-      this.replaceSession({ ...session, archived: true, archivedAt: new Date().toISOString() });
-      if (this.getState().selectedSession?.id === session.id) {
-        this.socket.close();
-        this.setState({ status: undefined, activity: undefined });
+      const state = this.getState();
+      const sessions = markSessionArchived(state.sessions, session.id, new Date().toISOString());
+      const selectionChange = selectionAfterArchivingSession(sessions, state.selectedSession?.id, session.id);
+      this.setState({ sessions });
+
+      if (selectionChange.type === "select") await this.selectSession(selectionChange.session);
+      else if (selectionChange.type === "clear") {
+        this.clearActiveSession();
+        this.updateUrl();
       }
     } catch (error) {
       this.setState({ error: String(error) });
diff --git a/src/client/src/controllers/sessionSelection.test.ts b/src/client/src/controllers/sessionSelection.test.ts
new file mode 100644
index 0000000..cfe527c
--- /dev/null
+++ b/src/client/src/controllers/sessionSelection.test.ts
@@ -0,0 +1,40 @@
+import { describe, expect, it } from "vitest";
+import type { SessionInfo } from "../api";
+import { markSessionArchived, selectionAfterArchivingSession } from "./sessionSelection";
+
+describe("markSessionArchived", () => {
+  it("marks the matching session archived without mutating the original", () => {
+    const sessions = [testSession("s1"), testSession("s2")];
+
+    const next = markSessionArchived(sessions, "s1", "later");
+
+    expect(next).toEqual([{ ...sessions[0], archived: true, archivedAt: "later" }, sessions[1]]);
+    expect(sessions[0]?.archived).toBeUndefined();
+  });
+});
+
+describe("selectionAfterArchivingSession", () => {
+  it("leaves selection unchanged when archiving an unselected session", () => {
+    expect(selectionAfterArchivingSession([testSession("s1"), testSession("s2")], "s1", "s2")).toEqual({ type: "unchanged" });
+  });
+
+  it("selects the first active session when archiving the selected session", () => {
+    const s2 = testSession("s2");
+
+    expect(selectionAfterArchivingSession([testSession("s1"), s2], "s1", "s1")).toEqual({ type: "select", session: s2 });
+  });
+
+  it("skips archived sessions when choosing the next selected session", () => {
+    const s3 = testSession("s3");
+
+    expect(selectionAfterArchivingSession([testSession("s1"), { ...testSession("s2"), archived: true }, s3], "s1", "s1")).toEqual({ type: "select", session: s3 });
+  });
+
+  it("clears selection when no active session remains", () => {
+    expect(selectionAfterArchivingSession([testSession("s1")], "s1", "s1")).toEqual({ type: "clear" });
+  });
+});
+
+function testSession(id: string): SessionInfo {
+  return { id, path: `/tmp/project/.pi/sessions/${id}`, cwd: "/tmp/project", created: "now", modified: "now", messageCount: 0, firstMessage: "" };
+}
diff --git a/src/client/src/controllers/sessionSelection.ts b/src/client/src/controllers/sessionSelection.ts
new file mode 100644
index 0000000..d1ce117
--- /dev/null
+++ b/src/client/src/controllers/sessionSelection.ts
@@ -0,0 +1,17 @@
+import type { SessionInfo } from "../api";
+
+export type ArchiveSelectionChange =
+  | { type: "unchanged" }
+  | { type: "select"; session: SessionInfo }
+  | { type: "clear" };
+
+export function markSessionArchived(sessions: SessionInfo[], sessionId: string, archivedAt: string): SessionInfo[] {
+  return sessions.map((session) => session.id === sessionId ? { ...session, archived: true, archivedAt } : session);
+}
+
+export function selectionAfterArchivingSession(sessions: SessionInfo[], selectedSessionId: string | undefined, archivedSessionId: string): ArchiveSelectionChange {
+  if (selectedSessionId !== archivedSessionId) return { type: "unchanged" };
+
+  const nextSession = sessions.find((session) => session.id !== archivedSessionId && session.archived !== true);
+  return nextSession === undefined ? { type: "clear" } : { type: "select", session: nextSession };
+}