diff --git a/src/core/OriginHeaders.ts b/src/core/OriginHeaders.ts
index 36d912e..e9bc563 100644
--- a/src/core/OriginHeaders.ts
+++ b/src/core/OriginHeaders.ts
@@ -14,6 +14,11 @@ export interface OriginHeaderConfig {
 
 type RouteHandler = (route: Route) => Promise<void>;
 
+interface SessionRouteRegistration {
+	handler: RouteHandler;
+	onClose: () => void;
+}
+
 /**
  * Manages per-origin HTTP headers and installs request interception on a Playwright page.
  *
@@ -31,7 +36,7 @@ export class OriginHeaders {
 	private installedPage: Page | null = null;
 	private routeHandler: RouteHandler | null = null;
 	private rollbackRoutes: Array<{ page: Page; handler: RouteHandler }> = [];
-	private readonly sessionRoutes = new Map<Page, RouteHandler>();
+	private readonly sessionRoutes = new Map<Page, SessionRouteRegistration>();
 
 	constructor(config?: OriginHeaderConfig) {
 		if (config) {
@@ -101,9 +106,28 @@ export class OriginHeaders {
 		if (this.sessionRoutes.has(page)) return;
 
 		const handler = this.createRouteHandler();
-		const routePromise = page.route("**/*", handler);
-		if (routePromise) await routePromise;
-		this.sessionRoutes.set(page, handler);
+		const onClose = () => {
+			this.sessionRoutes.delete(page);
+		};
+		page.once("close", onClose);
+
+		try {
+			const routePromise = page.route("**/*", handler);
+			if (routePromise) await routePromise;
+		} catch (error) {
+			page.off("close", onClose);
+			throw error;
+		}
+
+		this.sessionRoutes.set(page, { handler, onClose });
+
+		// The page can close while route registration is awaiting Playwright.
+		// A close event that fires before ownership is recorded deletes nothing,
+		// so reconcile against the authoritative page state before returning.
+		if (page.isClosed()) {
+			page.off("close", onClose);
+			this.sessionRoutes.delete(page);
+		}
 	}
 
 	private createRouteHandler(): RouteHandler {
@@ -170,7 +194,8 @@ export class OriginHeaders {
 
 		const sessionRoutes = [...this.sessionRoutes];
 		this.sessionRoutes.clear();
-		for (const [page, handler] of sessionRoutes) {
+		for (const [page, { handler, onClose }] of sessionRoutes) {
+			page.off("close", onClose);
 			try {
 				await page.unroute("**/*", handler);
 			} catch {
diff --git a/tests/unit/OriginHeadersSessionLifecycle.test.ts b/tests/unit/OriginHeadersSessionLifecycle.test.ts
index 4035a73..d5dd4c9 100644
--- a/tests/unit/OriginHeadersSessionLifecycle.test.ts
+++ b/tests/unit/OriginHeadersSessionLifecycle.test.ts
@@ -2,9 +2,24 @@ import { describe, expect, it, vi } from "vitest";
 import { OriginHeaders } from "../../src/core/OriginHeaders.js";
 
 function createPage() {
+	let closed = false;
+	let closeHandler: (() => void) | null = null;
 	return {
 		route: vi.fn().mockResolvedValue(undefined),
 		unroute: vi.fn().mockResolvedValue(undefined),
+		once: vi.fn((event: string, handler: () => void) => {
+			if (event === "close") closeHandler = handler;
+		}),
+		off: vi.fn((event: string, handler: () => void) => {
+			if (event === "close" && closeHandler === handler) closeHandler = null;
+		}),
+		isClosed: vi.fn(() => closed),
+		emitClose: () => {
+			closed = true;
+			const handler = closeHandler;
+			closeHandler = null;
+			handler?.();
+		},
 	};
 }
 
@@ -22,15 +37,19 @@ describe("OriginHeaders session lifecycle", () => {
 
 		expect(firstPage.route).toHaveBeenCalledTimes(1);
 		expect(secondPage.route).toHaveBeenCalledTimes(1);
+		expect(firstPage.once).toHaveBeenCalledTimes(1);
+		expect(secondPage.once).toHaveBeenCalledTimes(1);
 		expect(firstPage.unroute).not.toHaveBeenCalled();
 		expect(secondPage.unroute).not.toHaveBeenCalled();
 
 		await headers.dispose();
 		expect(firstPage.unroute).toHaveBeenCalledTimes(1);
 		expect(secondPage.unroute).toHaveBeenCalledTimes(1);
+		expect(firstPage.off).toHaveBeenCalledTimes(1);
+		expect(secondPage.off).toHaveBeenCalledTimes(1);
 	});
 
-	it("does not claim ownership when a session route registration fails", async () => {
+	it("does not retain ownership or a close listener when route registration fails", async () => {
 		const headers = new OriginHeaders({
 			"https://api.example.com": { Authorization: "Bearer secret" },
 		});
@@ -38,12 +57,49 @@ describe("OriginHeaders session lifecycle", () => {
 		page.route.mockRejectedValue(new Error("route unavailable"));
 
 		await expect(headers.installSessionPage(page as any)).rejects.toThrow("route unavailable");
+		expect(page.once).toHaveBeenCalledTimes(1);
+		expect(page.off).toHaveBeenCalledTimes(1);
 		await headers.dispose();
 
 		expect(page.unroute).not.toHaveBeenCalled();
 	});
 
-	it("disposes every session route best-effort even when one page is already gone", async () => {
+	it("releases a naturally closed page without touching a surviving sibling", async () => {
+		const headers = new OriginHeaders({
+			"https://api.example.com": { Authorization: "Bearer secret" },
+		});
+		const closedPage = createPage();
+		const livePage = createPage();
+
+		await headers.installSessionPage(closedPage as any);
+		await headers.installSessionPage(livePage as any);
+		closedPage.emitClose();
+
+		expect(closedPage.unroute).not.toHaveBeenCalled();
+		expect(livePage.unroute).not.toHaveBeenCalled();
+
+		await headers.dispose();
+		expect(closedPage.unroute).not.toHaveBeenCalled();
+		expect(livePage.unroute).toHaveBeenCalledTimes(1);
+	});
+
+	it("reconciles a page that closes while route registration is pending", async () => {
+		const headers = new OriginHeaders({
+			"https://api.example.com": { Authorization: "Bearer secret" },
+		});
+		const page = createPage();
+		page.route.mockImplementation(async () => {
+			page.emitClose();
+		});
+
+		await headers.installSessionPage(page as any);
+		await headers.dispose();
+
+		expect(page.isClosed).toHaveBeenCalled();
+		expect(page.unroute).not.toHaveBeenCalled();
+	});
+
+	it("disposes every still-owned session route best-effort when a close event was missed", async () => {
 		const headers = new OriginHeaders({
 			"https://api.example.com": { Authorization: "Bearer secret" },
 		});
diff --git a/tests/unit/OriginHeadersSessionRouting.test.ts b/tests/unit/OriginHeadersSessionRouting.test.ts
index aada858..ef22067 100644
--- a/tests/unit/OriginHeadersSessionRouting.test.ts
+++ b/tests/unit/OriginHeadersSessionRouting.test.ts
@@ -35,17 +35,30 @@ const emptyState = {
 };
 
 function createPage(order: string[]) {
+	let closed = false;
+	let closeHandler: (() => void) | null = null;
 	return {
 		route: vi.fn(async () => {
 			order.push("route");
 		}),
 		unroute: vi.fn().mockResolvedValue(undefined),
 		on: vi.fn(),
+		once: vi.fn((event: string, handler: () => void) => {
+			if (event === "close") closeHandler = handler;
+		}),
+		off: vi.fn((event: string, handler: () => void) => {
+			if (event === "close" && closeHandler === handler) closeHandler = null;
+		}),
 		goto: vi.fn(async () => {
 			order.push("goto");
 		}),
-		close: vi.fn().mockResolvedValue(undefined),
-		isClosed: vi.fn(() => false),
+		close: vi.fn(async () => {
+			closed = true;
+			const handler = closeHandler;
+			closeHandler = null;
+			handler?.();
+		}),
+		isClosed: vi.fn(() => closed),
 	};
 }
 
@@ -123,9 +136,11 @@ describe("OriginHeaders session routing", () => {
 		await controller.closePage(1);
 
 		expect(firstPage.unroute).not.toHaveBeenCalled();
+		expect(secondPage.unroute).not.toHaveBeenCalled();
 		expect(firstPage.route).toHaveBeenCalledTimes(1);
 		await (controller as any).disposeOriginHeaders();
 		expect(firstPage.unroute).toHaveBeenCalledTimes(1);
+		expect(secondPage.unroute).not.toHaveBeenCalled();
 	});
 
 	it("installs origin headers on the recreated page before snapshot restoration navigation", async () => {