feat: reuse existing tabs when opening sessions instead of always creating new ones

Use named window targets (session-{id}, instance-{id}) instead of _blank:
- use-instance-actions.ts: window.open(..., 'session-{id}') for programmatic opens
- session-card.tsx: <a target='session-{id}'> for direct link opens (mobile + desktop)
- workspace-instance-chips.tsx: <a target='instance-{id}'> for chip links
- instance-list.tsx: <a target='instance-{id}'> for instance open links

Browser behavior: if a tab with that target name exists, it navigates/focuses
that tab instead of opening a new one.

Quality gates: tsc --noEmit pass, npm run build pass, 80/80 tests pass

apps/web/src/components/features/project/repositories-settings-tab.test.tsx

@@ -1,4 +1,10 @@
-import { cleanup, fireEvent, render, screen, waitFor } from "@testing-library/react";
+import {
+	cleanup,
+	fireEvent,
+	render,
+	screen,
+	waitFor,
+} from "@testing-library/react";
 import { afterEach, describe, expect, it, vi } from "vitest";
 
 import { RepositoriesSettingsTab } from "./repositories-settings-tab";
@@ -20,7 +26,10 @@ const mockRepositories = [
 ];
 
 vi.mock("react-router-dom", async () => {
-  const actual = await vi.importActual<typeof import("react-router-dom")>("react-router-dom");
+	const actual =
+		await vi.importActual<typeof import("react-router-dom")>(
+			"react-router-dom",
+		);
 	return {
 		...actual,
 		useParams: () => ({ projectId: "proj-1" }),
@@ -34,10 +43,19 @@ afterEach(() => {
 
 describe("RepositoriesSettingsTab", () => {
 	it("opens create dialog and clones an existing repository", async () => {
-    const listMock = vi.spyOn(gitRepositoriesApi, "listRepositories").mockResolvedValue(mockRepositories);
+		const listMock = vi
-    const createMock = vi.spyOn(gitRepositoriesApi, "createRepository").mockResolvedValue(mockRepositories[0]);
+			.spyOn(gitRepositoriesApi, "listRepositories")
+			.mockResolvedValue(mockRepositories);
+		const createMock = vi
+			.spyOn(gitRepositoriesApi, "createRepository")
+			.mockResolvedValue(mockRepositories[0]);
 		vi.spyOn(sshKeysApi, "listSSHKeys").mockResolvedValue([
-      { id: "key-1", name: "My Key", public_key: "ssh-ed25519 AAA...", created_at: "2024-01-01" },
+			{
+				id: "key-1",
+				name: "My Key",
+				public_key: "ssh-ed25519 AAA...",
+				created_at: "2024-01-01",
+			},
 		]);
 
 		render(<RepositoriesSettingsTab />);
@@ -57,7 +75,9 @@ describe("RepositoriesSettingsTab", () => {
 			target: { value: "demo" },
 		});
 		const sshSelect = screen.getByRole("combobox", { name: /ssh key/i });
-    await waitFor(() => expect(sshSelect.querySelector('option[value="key-1"]')).toBeTruthy());
+		await waitFor(() =>
+			expect(sshSelect.querySelector('option[value="key-1"]')).toBeTruthy(),
+		);
 		(sshSelect as HTMLSelectElement).value = "key-1";
 		fireEvent.change(sshSelect);
 		fireEvent.click(screen.getByRole("button", { name: /clone repository/i }));
@@ -73,8 +93,12 @@ describe("RepositoriesSettingsTab", () => {
 	});
 
 	it("uses advanced url fallback when requested", async () => {
-    const listMock = vi.spyOn(gitRepositoriesApi, "listRepositories").mockResolvedValue(mockRepositories);
+		const listMock = vi
-    const createMock = vi.spyOn(gitRepositoriesApi, "createRepository").mockResolvedValue(mockRepositories[0]);
+			.spyOn(gitRepositoriesApi, "listRepositories")
+			.mockResolvedValue(mockRepositories);
+		const createMock = vi
+			.spyOn(gitRepositoriesApi, "createRepository")
+			.mockResolvedValue(mockRepositories[0]);
 		vi.spyOn(sshKeysApi, "listSSHKeys").mockResolvedValue([]);
 
 		render(<RepositoriesSettingsTab />);
@@ -87,10 +111,15 @@ describe("RepositoriesSettingsTab", () => {
 		fireEvent.change(screen.getByPlaceholderText(/repository-name/i), {
 			target: { value: "New Repo" },
 		});
-    fireEvent.click(screen.getByRole("button", { name: /use full url instead/i }));
+		fireEvent.click(
-    fireEvent.change(screen.getByPlaceholderText(/https:\/\/github.com\/user\/repo.git/i), {
+			screen.getByRole("button", { name: /use full url instead/i }),
+		);
+		fireEvent.change(
+			screen.getByPlaceholderText(/https:\/\/github.com\/user\/repo.git/i),
+			{
 				target: { value: "https://github.com/user/repo.git" },
-    });
+			},
+		);
 		fireEvent.click(screen.getByRole("button", { name: /clone repository/i }));
 
 		await waitFor(() => {
@@ -103,7 +132,9 @@ describe("RepositoriesSettingsTab", () => {
 	});
 
 	it("shows validation when cloning without a remote url", async () => {
-    vi.spyOn(gitRepositoriesApi, "listRepositories").mockResolvedValue(mockRepositories);
+		vi.spyOn(gitRepositoriesApi, "listRepositories").mockResolvedValue(
+			mockRepositories,
+		);
 		render(<RepositoriesSettingsTab />);
 
 		await waitFor(() => {
@@ -119,6 +150,8 @@ describe("RepositoriesSettingsTab", () => {
 		});
 		fireEvent.click(screen.getByRole("button", { name: /clone repository/i }));
 
-    expect(screen.getByText(/owner and repository name are required/i)).toBeInTheDocument();
+		expect(
+			screen.getByText(/owner and repository name are required/i),
+		).toBeInTheDocument();
 	});
 });

apps/web/src/components/features/session/session-card.tsx

@@ -138,7 +138,7 @@ export function SessionCard({
 					)}
 					{session.url && (
 						<p className="session-card-url">
-							<a href={session.url} target="_blank" rel="noopener noreferrer">
+							<a href={session.url} target={`session-${session.id}`} rel="noopener noreferrer">
 								{session.url}
 							</a>
 						</p>
@@ -158,7 +158,7 @@ export function SessionCard({
 							{openHref ? (
 								<a
 									href={openHref}
-									target="_blank"
+									target={`session-${session.id}`}
 									rel="noopener noreferrer"
 									className="secondary-button mobile-primary"
 								>
@@ -215,7 +215,7 @@ export function SessionCard({
 							{openHref ? (
 								<a
 									href={openHref}
-									target="_blank"
+									target={`session-${session.id}`}
 									rel="noopener noreferrer"
 									className="secondary-button small"
 								>

apps/web/src/components/features/tool/instance-list.tsx

@@ -282,7 +282,7 @@ export const InstanceList = ({
 														? instance.url
 														: `${API_BASE_URL}${instance.url}`
 												}
-												target="_blank"
+												target={`instance-${instance.id}`}
 												rel="noopener noreferrer"
 												className="secondary-button small"
 											>

apps/web/src/components/features/workspace/workspace-instance-chips.tsx

@@ -43,7 +43,7 @@ export function WorkspaceInstanceChips({
 					{inst.status === "running" && inst.url && (
 						<a
 							href={inst.url}
-							target="_blank"
+							target={`instance-${inst.id}`}
 							rel="noopener noreferrer"
 							onClick={(e) => e.stopPropagation()}
 						>

apps/web/src/hooks/use-instance-actions.ts

@@ -35,15 +35,16 @@ export function useInstanceActions(
 	const [dirtyDeleteFiles, setDirtyDeleteFiles] = useState<string[]>([]);
 
 	const handleOpen = useCallback((session: Session) => {
+		const tabName = `session-${session.id}`;
 		if (session.url) {
-			window.open(session.url, "_blank", "noopener,noreferrer");
+			window.open(session.url, tabName, "noopener,noreferrer");
 			return;
 		}
 		if (session.tool_type_interfaces?.includes("terminal")) {
-			window.open(`/instances/${session.id}/terminal`, "_blank", "noopener,noreferrer");
+			window.open(`/instances/${session.id}/terminal`, tabName, "noopener,noreferrer");
 			return;
 		}
-		window.open(`/projects/${session.project_id}`, "_blank", "noopener,noreferrer");
+		window.open(`/projects/${session.project_id}`, tabName, "noopener,noreferrer");
 	}, []);
 
 	const handleStart = useCallback(