diff --git a/Agent.md b/Agent.md
index e6f742a4..5c257937 100644
--- a/Agent.md
+++ b/Agent.md
@@ -54,7 +54,7 @@ What EMRG does today — capability statements, not a changelog.
 One line per command: what it answers. Run the daemon in the foreground with `python -m emrg`.
 
 - Python: `uv run pytest tests/ -v` — the number is **measured, never stored**: `uv run --no-sync python3 scripts/check-doc-count.py --measure`. Import check: `uv run python -c "from emrg.client.app import run_client"`
-GUI: `cd emrg/gui && npm test` (168: 100 daemon_client + 20 conn-manager + 7 integration + 7 nav-policy + 7 gui-state + 9 build-config + 11 boot-contract + 3 preload-api + 2 theme-guard + 2 image-hash) — syntax: `node --check main.js preload.js daemon_client.js`
+GUI: `cd emrg/gui && npm test` (169: 100 daemon_client + 20 conn-manager + 7 integration + 7 nav-policy + 7 gui-state + 9 build-config + 12 boot-contract + 3 preload-api + 2 theme-guard + 2 image-hash) — syntax: `node --check main.js preload.js daemon_client.js`
 Renderer: `cd emrg/gui/renderer && npm run typecheck && npm test` (740: 5 snapshot-store + 13 utils + 3 ErrorBoundary + 2 App smoke + 11 commands + 4 copywriting + 11 i18n + 13 markdown + 29 transcript + 28 TranscriptView + 22 history + 25 historyReplay + 40 composer + 75 Composer + 6 LinkDialog + 16 sidebar + 18 Sidebar + 9 fileTree + 9 FileTree + 17 resultPanel + 8 ResultPanel + 27 workspaceView + 13 WorkspaceView + 10 dialog + 6 Dialog + 9 ConfirmDialog + 9 RenameDialog + 12 dialogLists + 3 HelpDialog + 9 MemoryDialog + 8 SkillsDialog + 8 openSession + 6 WelcomeDialog + 9 OpenSessionDialog + 7 NewSessionDialog + 7 rewind + 8 RewindDialog + 7 GithubDeviceDialog + 59 daemonBridge + 9 DaemonBridgeProvider + 50 Shell + 25 DialogHost + 26 SettingsPanel + 18 TaskFormDialog + 5 RantDialog + 4 vendorMarkdown + 6 ApprovalDialog + 16 SandboxRootsDialog)
 - CI: pytest on ubuntu **and windows-2025**, the GUI suites, and an actionlint gate over `.github/workflows/`; re-trigger a dropped push with `scripts/re-trigger-ci.sh <branch>`, never an empty commit
 - Merge gates, run before merging — each asks what no other gate asks: `uv run --no-sync python3 scripts/check-vote-count.py` (approvals still valid) · `scripts/check-pr-base.py` (base reaches master) · `scripts/check-merge-freshness.py` (that green CI is about the landing tree) · `scripts/check-merge-order.py` (dirt and what it lands) · `scripts/check-merge-landing-diff.py` (what the landing changes) · `scripts/check-merge-pairs.py` / `scripts/check-merge-sequence.py` (a pair, or a whole order) · `scripts/check-merge-tree-health.py` (the merged tree passes one guard) · `scripts/check-merge-plan-suite.py` (the plan's final tree passes the suite) — all under `uv run --no-sync python3`
diff --git a/emrg/gui/main.js b/emrg/gui/main.js
index 516fae1e..12f49b4b 100644
--- a/emrg/gui/main.js
+++ b/emrg/gui/main.js
@@ -584,11 +584,9 @@ vision = false
         logger.warn(`[gui:switch] REJECT too many open sessions (${openSessions.size}/${DEFAULT_CAP}) sid=${sessionId}`);
         throw new Error(`too many open sessions (${DEFAULT_CAP}) — close some first`);
       }
-      // G65：自有流运行中禁止切会话（每连接独立锁，查当前激活连接）
-      if (connManager?.get(currentSessionId)?.ownStream) {
-        logger.warn(`[gui:switch] REJECT own stream in progress (sid=${currentSessionId})`);
-        throw new Error("stream in progress — cannot switch");
-      }
+      // issue #2637：切会话不看 ownStream。自有流跑在它自己会话的连接上，切换不动它
+      // （P4：切走不关闭旧连接），所以「流运行中禁止切」只拒绝、不保护。G65 锁仍归
+      // close() / cancel 用：conn-manager 关闭在忙连接时先 cancel 再断 ws。
       const prevSid = currentSessionId;
       logger.info(`[gui:switch] prevSid=${prevSid} → target=${sessionId}, openSessions.size=${openSessions.size}`);
       // G110：切会话清空旧连接分组缓存（含 timer），防广播"幽灵"残留
diff --git a/emrg/gui/renderer/src/components/Shell.tsx b/emrg/gui/renderer/src/components/Shell.tsx
index 2daa880d..cf5a4ca9 100644
--- a/emrg/gui/renderer/src/components/Shell.tsx
+++ b/emrg/gui/renderer/src/components/Shell.tsx
@@ -322,7 +322,19 @@ export function Shell() {
 
   async function selectProjectSession(p: AgentRec, sid: string) {
     const b = wsBridge();
-    if (b?.switchSession) await b.switchSession({ sessionId: sid });
+    // issue #2637：这里原来没有 catch —— 一次拒绝就是未处理的 promise 拒绝，界面毫无
+    // 反应（与任务面板的 catch 不对称）。拒绝要有落点。
+    if (b?.switchSession) {
+      try {
+        await b.switchSession({ sessionId: sid });
+      } catch (e) {
+        transcript.addSystemMessage(
+          t("openSession.loadFailed", { msg: (e as Error)?.message ?? String(e) }),
+          activeSid,
+        );
+        return;
+      }
+    }
     setActiveSid(sid);
     setActiveView("sessions");
     void loadHistory(sid);
diff --git a/emrg/gui/test/boot-contract.test.js b/emrg/gui/test/boot-contract.test.js
index 77639c58..5126ce55 100644
--- a/emrg/gui/test/boot-contract.test.js
+++ b/emrg/gui/test/boot-contract.test.js
@@ -338,3 +338,34 @@ test("issue #2490: emrg:taskLimits reports the daemon's own minimum, never a lit
     "no literal floor may live in this handler — that is the copy issue #2490 removes"
   );
 });
+
+// issue #2637：切会话不再因「当前会话自有流运行中」被拒。
+// 那条拒绝成立过一个年代：切换当时会关闭旧连接，而 close() 对 ownStream 连接先发
+// cancel 再断 ws（conn-manager.test.js 的 P6 正钉着「先 cancel 再 close」），于是放行
+// 切换就等于静默杀掉正在跑的那一轮。此后切换改为不动旧连接（关闭是 emrg:closeSession
+// 的事），每会话各有 ws 与记录桶 ⇒ 那条拒绝只剩拒绝本身，而它的两个调用方都把拒绝说
+// 在用户看不见的地方：侧边栏没有 catch（未处理的 promise 拒绝、界面毫无反应），任务
+// 面板的 catch 写进「正在离开的」那个会话的记录。
+test("issue #2637: emrg:switchSession does not consult ownStream to refuse a switch", () => {
+  // 「查了没有」问的是代码，不是注释：注释里点到这把锁的正当改版必须静默，代码里真去
+  // 读它必须变红 —— 两条都在下面各钉一次，否则这个谓词读不出任何东西。
+  const withoutLineComments = (s) => s.replace(/^\s*\/\/.*$/gm, "");
+  const region = handlerRegion(read("main.js"), "emrg:switchSession");
+  assert.ok(
+    !/ownStream/.test(withoutLineComments(region)),
+    "a streaming turn lives on its own session's connection and outlives the switch, so " +
+      "refusing the navigation protects nothing; the lock still matters to close(), which " +
+      "cancels a busy connection — it just must not gate switching",
+  );
+  assert.ok(
+    !/ownStream/.test(withoutLineComments("// 切会话不查 ownStream\nfoo();")),
+    "a comment naming the lock is not a consultation of it",
+  );
+  assert.ok(
+    /ownStream/.test(withoutLineComments('if (c?.ownStream) throw new Error("x");')),
+    "reading it in code is still caught — else this guard reads nothing at all",
+  );
+  // 反方向：同一段里别的拒绝不许被一起带走。
+  assert.match(region, /REJECT invalid session_id/, "session-id validation stays a refusal");
+  assert.match(region, /too many open sessions/, "the open-session cap stays a refusal");
+});