feat(maestro): force-kill prompt in the web client

The kill button now sends the unforced DELETE immediately instead of
asking first. Only the daemon's guard refusal raises a prompt, and it is
a real dialog rather than confirm(), so it can offer the override the
daemon already implements.

The API error envelope is decoded into ApiRequestError, keeping the code
and the unsaved-work breakdown so the dialog names what is in the way.

web/src/catalog.test.ts

@@ -1,5 +1,5 @@
 // @vitest-environment happy-dom
-import { beforeAll, describe, expect, it } from "vitest";
+import { afterEach, beforeAll, describe, expect, it } from "vitest";
 
 import { renderSidebar } from "./catalog.js";
 import type { CatalogListener, CatalogStore } from "./events.js";
@@ -16,6 +16,10 @@ beforeAll(() => {
   window.fetch = () => Promise.reject(new Error("offline"));
 });
 
+afterEach(() => {
+  document.querySelector(".kill-dialog")?.remove();
+});
+
 function session(overrides: Partial<Session>): Session {
   return {
     id: "11111111-2222-3333-4444-555555555555",
@@ -46,6 +50,11 @@ function rowFor(el: HTMLElement, id: string): HTMLElement | null {
   return el.querySelector<HTMLElement>(`[data-session-id="${id}"]`);
 }
 
+/** Let the kill chain's awaits (fetch, its json body) settle. */
+async function flush(): Promise<void> {
+  for (let i = 0; i < 8; i++) await Promise.resolve();
+}
+
 describe("blocked-work indicator (#83)", () => {
   it("marks the row of a blocked session in diff notation", () => {
     const blocked = session({
@@ -89,37 +98,77 @@ describe("blocked-work indicator (#83)", () => {
     expect(rowFor(el, unprobed.id)?.querySelector(".leaf-blocked")).toBeNull();
   });
 
-  it("restates the warning at the kill confirm", async () => {
-    const confirmations: string[] = [];
-    window.confirm = (msg?: string) => {
-      confirmations.push(msg ?? "");
-      return false;
-    };
+  it("kills straight away, without a first confirmation", async () => {
+    const calls: string[] = [];
+    window.fetch = ((url: string, init?: RequestInit) => {
+      calls.push(`${init?.method ?? "GET"} ${url}`);
+      return Promise.resolve(new Response(null, { status: 204 }));
+    }) as typeof fetch;
+    const plain = session({ id: "aaaaaaaa-0000-0000-0000-000000000005" });
+    const el = renderSidebar(storeWith([plain])).el;
+    rowFor(el, plain.id)?.querySelector<HTMLButtonElement>(".leaf-kill")?.click();
+    await flush();
+    expect(calls).toContain(`DELETE /api/sessions/${plain.id}`);
+    expect(document.querySelector(".kill-dialog")).toBeNull();
+  });
+
+  it("offers the override when the daemon refuses a guarded kill", async () => {
+    const calls: string[] = [];
+    window.fetch = ((url: string, init?: RequestInit) => {
+      calls.push(`${init?.method ?? "GET"} ${url}`);
+      if (url.includes("force=true")) return Promise.resolve(new Response(null, { status: 204 }));
+      return Promise.resolve(
+        new Response(
+          JSON.stringify({
+            error: {
+              code: "kill_guarded",
+              message: "worktree has unsaved work",
+              unsaved_work: { untracked_files: 1 },
+            },
+          }),
+          { status: 409, headers: { "content-type": "application/json" } },
+        ),
+      );
+    }) as typeof fetch;
     const blocked = session({
       id: "aaaaaaaa-0000-0000-0000-000000000004",
       command: "bash",
       blocked_work: { untracked_files: 1 },
     });
     const el = renderSidebar(storeWith([blocked])).el;
-    const kill = rowFor(el, blocked.id)?.querySelector<HTMLButtonElement>(".leaf-kill");
-    kill?.click();
-    await Promise.resolve();
-    expect(confirmations).toHaveLength(1);
-    expect(confirmations[0]).toContain("1 untracked file");
-    expect(confirmations[0]).toContain("refused unless forced");
+    rowFor(el, blocked.id)?.querySelector<HTMLButtonElement>(".leaf-kill")?.click();
+    await flush();
+    const dialog = document.querySelector(".kill-dialog");
+    expect(dialog?.textContent).toContain("1 untracked file");
+    dialog?.querySelector<HTMLButtonElement>(".kill-dialog-force")?.click();
+    await flush();
+    expect(calls).toContain(`DELETE /api/sessions/${blocked.id}?force=true`);
+    expect(document.querySelector(".kill-dialog")).toBeNull();
   });
 
-  it("confirms plainly when nothing blocks", async () => {
-    const confirmations: string[] = [];
-    window.confirm = (msg?: string) => {
-      confirmations.push(msg ?? "");
-      return false;
-    };
-    const plain = session({ id: "aaaaaaaa-0000-0000-0000-000000000005" });
-    const el = renderSidebar(storeWith([plain])).el;
-    rowFor(el, plain.id)?.querySelector<HTMLButtonElement>(".leaf-kill")?.click();
-    await Promise.resolve();
-    expect(confirmations).toEqual(['Kill session "claude"?']);
+  it("closes the override prompt without killing on cancel", async () => {
+    const calls: string[] = [];
+    window.fetch = ((url: string, init?: RequestInit) => {
+      calls.push(`${init?.method ?? "GET"} ${url}`);
+      return Promise.resolve(
+        new Response(
+          JSON.stringify({
+            error: { code: "kill_guarded", message: "worktree has unsaved work" },
+          }),
+          { status: 409, headers: { "content-type": "application/json" } },
+        ),
+      );
+    }) as typeof fetch;
+    const blocked = session({
+      id: "aaaaaaaa-0000-0000-0000-000000000006",
+      blocked_work: { unpushed_commits: 2 },
+    });
+    const el = renderSidebar(storeWith([blocked])).el;
+    rowFor(el, blocked.id)?.querySelector<HTMLButtonElement>(".leaf-kill")?.click();
+    await flush();
+    document.querySelector<HTMLButtonElement>(".kill-dialog-cancel")?.click();
+    expect(document.querySelector(".kill-dialog")).toBeNull();
+    expect(calls.filter((c) => c.includes("force=true"))).toHaveLength(0);
   });
 });