feat(maestro): drill into a session's action page with tab

Tab on a highlighted session in the web command bar opens that session's
action page in the same overlay: kill, rename, spawn similar, still fuzzy
searchable and headed by the session's name. Escape, or backspace at an
empty query, returns to the result list with the previous query intact.

Each action raises the flow the card already has. The two that lived
inside the sidebar get an event apiece — the confirm-and-blockers kill and
the inline rename prompt — so the bar picks the action and nothing more;
spawn similar reuses the existing SPAWN_SIMILAR_EVENT.

web/src/commandBar.test.ts

@@ -1,7 +1,12 @@
 // @vitest-environment happy-dom
 import { afterEach, describe, expect, it, vi } from "vitest";
 
-import { SESSION_SELECT_EVENT } from "./catalog.js";
+import {
+  KILL_SESSION_EVENT,
+  RENAME_SESSION_EVENT,
+  SESSION_SELECT_EVENT,
+  SPAWN_SIMILAR_EVENT,
+} from "./catalog.js";
 import {
   barGroups,
   barRows,
@@ -15,6 +20,7 @@ import {
   orderSessionsForBar,
   parseBarQuery,
   sessionBarCandidates,
+  sessionActionCandidates,
   sessionCandidate,
   SPAWN_DIRECTORY_EVENT,
 } from "./commandBar.js";
@@ -542,3 +548,176 @@ describe("the focus round-trip over a pane (#152)", () => {
     }
   });
 });
+
+describe("the session action page (#151)", () => {
+  const sessions = [
+    session("api", {
+      metadata: { name: "api" },
+      current_cwd: "/home/me/dev/api",
+      last_focused_at: "2026-01-01T11:00:00Z",
+    }),
+    session("worker", {
+      metadata: { name: "worker" },
+      current_cwd: "/home/me/dev/worker",
+      last_focused_at: "2026-01-01T10:00:00Z",
+    }),
+  ];
+
+  function open(over: Partial<Parameters<typeof openCommandBar>[0]> = {}) {
+    return openCommandBar({
+      sessions,
+      homeDir: "/home/me",
+      commands: [],
+      onOpenSession: () => {},
+      ...over,
+    });
+  }
+
+  function headerText(): string | undefined {
+    return document.querySelector(".cmdbar-page-header")?.textContent ?? undefined;
+  }
+
+  it("lists kill, rename and spawn similar for the highlighted session", () => {
+    open();
+    press("Tab");
+    expect(rowNames()).toEqual(["Kill session", "Rename session", "Spawn similar"]);
+    expect(activeName()).toBe("Kill session");
+  });
+
+  it("names the session being acted on", () => {
+    open();
+    press("ArrowDown");
+    press("Tab");
+    expect(headerText()).toContain("worker");
+  });
+
+  it("drops the kind headers, since the page is one kind", () => {
+    open();
+    press("Tab");
+    expect(document.querySelectorAll(".cmdbar-group-title")).toHaveLength(0);
+  });
+
+  it("stays fuzzy-searchable over the three actions", () => {
+    open();
+    press("Tab");
+    type("ren");
+    expect(rowNames()).toEqual(["Rename session"]);
+    type("spwn");
+    expect(rowNames()).toEqual(["Spawn similar"]);
+    type("zzz");
+    expect(document.querySelector(".cmdbar-empty")?.textContent).toBe("No matches");
+  });
+
+  it("does nothing on a command row", () => {
+    openCommandBar({
+      sessions,
+      homeDir: "/home/me",
+      commands: [{ ...COMMAND_SPECS[0], run: () => {} } as Command],
+      onOpenSession: () => {},
+    });
+    type(">");
+    const before = rowNames();
+    press("Tab");
+    expect(rowNames()).toEqual(before);
+    expect(headerText()).toBeUndefined();
+  });
+
+  it("does nothing on a directory row", async () => {
+    open({ loadDirectories: () => Promise.resolve(["/home/me/dev/api"]) });
+    type("~");
+    await Promise.resolve();
+    press("Tab");
+    expect(rowNames()).toEqual(["~/dev/api"]);
+    expect(headerText()).toBeUndefined();
+  });
+
+  it("returns to the result list on Escape, with the previous query intact", () => {
+    open();
+    type("wor");
+    press("Tab");
+    expect(headerText()).toContain("worker");
+    press("Escape");
+    expect(isCommandBarOpen()).toBe(true);
+    expect(headerText()).toBeUndefined();
+    expect((document.querySelector(".cmdbar-input") as HTMLInputElement).value).toBe("wor");
+    expect(rowNames()).toEqual(["worker"]);
+  });
+
+  it("returns to the result list on backspace at an empty query", () => {
+    open();
+    type("wor");
+    press("Tab");
+    type("");
+    press("Backspace");
+    expect(headerText()).toBeUndefined();
+    expect((document.querySelector(".cmdbar-input") as HTMLInputElement).value).toBe("wor");
+    expect(rowNames()).toEqual(["worker"]);
+  });
+
+  it("keeps backspace ordinary while the page's query has text", () => {
+    open();
+    press("Tab");
+    type("ren");
+    press("Backspace");
+    expect(headerText()).toContain("api");
+    expect(rowNames()).toEqual(["Rename session"]);
+  });
+
+  it("closes the bar when the page's Escape has already been used", () => {
+    open();
+    press("Tab");
+    press("Escape");
+    press("Escape");
+    expect(isCommandBarOpen()).toBe(false);
+  });
+
+  it("raises kill, rename and spawn similar with the session, closing the bar", () => {
+    const seen: string[] = [];
+    for (const [hook, key] of [
+      ["onKillSession", "Kill session"],
+      ["onRenameSession", "Rename session"],
+      ["onSpawnSimilar", "Spawn similar"],
+    ] as const) {
+      open({ [hook]: (s: Session) => seen.push(`${hook}:${s.id}`) });
+      type("wor");
+      press("Tab");
+      type(key);
+      press("Enter");
+      expect(isCommandBarOpen()).toBe(false);
+    }
+    expect(seen).toEqual([
+      "onKillSession:worker",
+      "onRenameSession:worker",
+      "onSpawnSimilar:worker",
+    ]);
+  });
+
+  it("hands each action to the flow it already has, by default", () => {
+    const seen: string[] = [];
+    const listeners: Array<[string, EventListener]> = [
+      [KILL_SESSION_EVENT, (e) => seen.push(`kill:${(e as CustomEvent<Session>).detail.id}`)],
+      [RENAME_SESSION_EVENT, (e) => seen.push(`rename:${(e as CustomEvent<Session>).detail.id}`)],
+      [SPAWN_SIMILAR_EVENT, (e) => seen.push(`similar:${(e as CustomEvent<Session>).detail.id}`)],
+    ];
+    for (const [name, fn] of listeners) document.addEventListener(name, fn);
+    try {
+      for (const action of ["Kill session", "Rename session", "Spawn similar"]) {
+        open();
+        press("Tab");
+        type(action);
+        press("Enter");
+      }
+    } finally {
+      for (const [name, fn] of listeners) document.removeEventListener(name, fn);
+    }
+    expect(seen).toEqual(["kill:api", "rename:api", "similar:api"]);
+  });
+
+  it("offers no action beyond the three", () => {
+    expect(sessionActionCandidates().map((c) => c.action.id)).toEqual([
+      "kill",
+      "rename",
+      "spawn-similar",
+    ]);
+  });
+});