feat: empty-container spawn (scratch workspace, no repo volume); fix bridge session isolation — explicit SessionManager per spawn stops SDK resuming the repo's old session (which also overrode LVMH_MODEL)

web/src/SpawnView.test.tsx

@@ -715,3 +715,28 @@ describe("spawn model selection", () => {
 		expect(bodies[0]).toContain('"model":"zai-renaud/glm-5.3"');
 	});
 });
+
+describe("empty container spawn", () => {
+	it("checkbox sends empty:true and resets after", async () => {
+		const bodies: string[] = [];
+		mockFetchJson((url, init) => {
+			if (init?.method === "POST" && url.endsWith("/api/spawn")) {
+				bodies.push(String(init.body));
+				return { sessionId: "e1", imageUsed: "lvmh-worker:latest" };
+			}
+			if (url.endsWith("/api/gitlab/status"))
+				return { connected: true, baseUrl: "https://gl", username: "a" };
+			if (url.endsWith("/api/gitlab/repos")) return [repo("g/p")];
+			return [];
+		});
+		render(tree(makeStore()));
+		await flush();
+		fireEvent.click(screen.getByText("g/p"));
+		const cb = screen.getByRole("checkbox");
+		fireEvent.click(cb);
+		expect(cb).toBeChecked();
+		fireEvent.click(screen.getByLabelText("Spawn container"));
+		await flush();
+		expect(bodies[0]).toContain('"empty":true');
+	});
+});

web/src/SpawnView.tsx

@@ -61,6 +61,7 @@ export default function SpawnView({ store, pushToast }: Props) {
 	const [query, setQuery] = useState<string>("");
 	const [selected, setSelected] = useState<Repo | null>(null);
 	const [branch, setBranch] = useState<string>("");
+	const [empty, setEmpty] = useState<boolean>(false);
 	const [model, setModel] = useState<string>("");
 	const [catalog, setCatalog] = useState<ModelCatalogEntry[] | null>(null);
 	const [busy, setBusy] = useState<boolean>(false);
@@ -176,6 +177,7 @@ export default function SpawnView({ store, pushToast }: Props) {
 				repo: selected!.path,
 				...(branch.trim().length > 0 ? { branch: branch.trim() } : {}),
 				...(model.length > 0 ? { model } : {}),
+				...(empty ? { empty: true } : {}),
 			};
 			const res = await fetchJson<SpawnResponse>(Route.Spawn, {
 				method: "POST",
@@ -429,6 +431,18 @@ export default function SpawnView({ store, pushToast }: Props) {
 									))}
 							</select>
 						</div>
+						<label
+							className="repo-meta"
+							style={{ marginTop: 8, display: "flex", gap: 6, alignItems: "center" }}
+						>
+							<input
+								type="checkbox"
+								checked={empty}
+								onChange={(e) => setEmpty(e.target.checked)}
+								disabled={busy}
+							/>
+							Empty container (no repo — blank workspace)
+						</label>
 						{error.length > 0 && <p className="error-text">{error}</p>}
 					</div>
 				</>