From d1015748425c019d6467d74bb85c97b159095635 Mon Sep 17 00:00:00 2001
From: Miguel Palhas <mpalhas@gmail.com>
Date: Mon, 31 Aug 2026 09:16:15 +0100
Subject: [PATCH] feat(maestro): close a tab when its last session dies

Killing the only session in a tab left an empty tab behind for the operator to close by hand. The pane's tab now goes with it, unless it is the last tab (which stays, emptied).
---
 web/src/multiview.test.ts | 97 ++++++++++++++++++++++++++++++++++++++-
 web/src/multiview.ts      |  4 ++
 2 files changed, 100 insertions(+), 1 deletion(-)

diff --git a/web/src/multiview.test.ts b/web/src/multiview.test.ts
index a60d694..253715f 100644
--- a/web/src/multiview.test.ts
+++ b/web/src/multiview.test.ts
@@ -1,7 +1,7 @@
 // @vitest-environment happy-dom
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 
-import { emptyLayout, leaves, type Layout } from "./layout.js";
+import { addTab, emptyLayout, leaves, type Layout } from "./layout.js";
 import { splitLeaf } from "./layout.js";
 import { createMultiView, type MultiView } from "./multiview.js";
 import type { ConnectionPool } from "./connections.js";
@@ -333,3 +333,98 @@ describe("openDraft newTab (#100)", () => {
     expect(leaves(tab.root)).toHaveLength(2);
   });
 });
+
+describe("multiview closeSession tab cleanup (#137)", () => {
+  beforeEach(() => {
+    stubFetch();
+    document.body.replaceChildren();
+  });
+
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  it("closes the tab when its last session goes away", () => {
+    const layout = emptyLayout();
+    const first = layout.tabs[0];
+    first.focusedLeafId = splitLeaf(first, "", "s1", "row", true);
+    const second = addTab(layout);
+    second.focusedLeafId = splitLeaf(second, "", "s2", "row", true);
+    const mv = makeMv(layout);
+    document.body.appendChild(mv.el);
+    mv.render();
+
+    mv.closeSession("s2");
+
+    expect(layout.tabs).toHaveLength(1);
+    expect(layout.tabs[0].id).toBe(first.id);
+    expect(layout.activeTabId).toBe(first.id);
+  });
+
+  it("closes a background tab without stealing focus from the active one", () => {
+    const layout = emptyLayout();
+    const background = layout.tabs[0];
+    background.focusedLeafId = splitLeaf(background, "", "s1", "row", true);
+    const active = addTab(layout);
+    active.focusedLeafId = splitLeaf(active, "", "s2", "row", true);
+    const mv = makeMv(layout);
+    document.body.appendChild(mv.el);
+    mv.render();
+
+    mv.closeSession("s1");
+
+    expect(layout.tabs).toHaveLength(1);
+    expect(layout.tabs[0].id).toBe(active.id);
+    expect(layout.activeTabId).toBe(active.id);
+  });
+
+  it("keeps a tab that still holds another pane", () => {
+    const layout = emptyLayout();
+    const tab = layout.tabs[0];
+    const first = splitLeaf(tab, "", "s1", "row", true);
+    tab.focusedLeafId = splitLeaf(tab, first, "s2", "row", true);
+    addTab(layout);
+    layout.activeTabId = tab.id;
+    const mv = makeMv(layout);
+    document.body.appendChild(mv.el);
+    mv.render();
+
+    mv.closeSession("s2");
+
+    expect(layout.tabs).toHaveLength(2);
+    expect(leaves(tab.root)).toHaveLength(1);
+  });
+
+  it("keeps a tab holding a draft pane", async () => {
+    const layout = emptyLayout();
+    const tab = layout.tabs[0];
+    const s1 = splitLeaf(tab, "", "s1", "row", true);
+    splitLeaf(tab, s1, null, "row", true);
+    addTab(layout);
+    layout.activeTabId = tab.id;
+    const mv = makeMv(layout);
+    document.body.appendChild(mv.el);
+    mv.render();
+    await flush();
+
+    mv.closeSession("s1");
+
+    expect(layout.tabs).toHaveLength(2);
+    expect(leaves(tab.root)).toHaveLength(1);
+  });
+
+  it("never closes the only tab", () => {
+    const layout = emptyLayout();
+    const tab = layout.tabs[0];
+    tab.focusedLeafId = splitLeaf(tab, "", "s1", "row", true);
+    const mv = makeMv(layout);
+    document.body.appendChild(mv.el);
+    mv.render();
+
+    mv.closeSession("s1");
+
+    expect(layout.tabs).toHaveLength(1);
+    expect(layout.tabs[0].root).toBeNull();
+    expect(layout.activeTabId).toBe(tab.id);
+  });
+});
diff --git a/web/src/multiview.ts b/web/src/multiview.ts
index b459c81..f19de89 100644
--- a/web/src/multiview.ts
+++ b/web/src/multiview.ts
@@ -553,6 +553,10 @@ export function createMultiView(opts: MultiViewOptions): MultiView {
     if (loc.tab.focusedLeafId === loc.leaf.id) {
       loc.tab.focusedLeafId = leaves(loc.tab.root)[0]?.id ?? null;
     }
+    // A tab that held nothing but the dead session goes with it (#137): a killed
+    // session should not leave an empty tab behind for the operator to close by
+    // hand. `closeTab` keeps the last tab (emptied) so there is always one.
+    if (!loc.tab.root) closeTab(layout, loc.tab.id);
     render();
   }