diff --git a/app/components/Launcher.vue b/app/components/Launcher.vue
index 9e68e186d..d6747d3c2 100644
--- a/app/components/Launcher.vue
+++ b/app/components/Launcher.vue
@@ -3,6 +3,7 @@ import Loading from "@ogw_front/components/Loading.vue";
 import Recaptcha from "@ogw_front/components/Recaptcha.vue";
 import { Status } from "@ogw_front/utils/status";
 import { appMode } from "@ogw_shared/app_mode";
+import { getCloudUrlParam } from "@ogw_front/utils/cloud";
 import { useInfraStore } from "@ogw_front/stores/infra";
 
 interface Props {
@@ -15,8 +16,10 @@ interface Props {
 const { appName, email = undefined, isUserAuthenticated = false, logo = "" } = defineProps<Props>();
 
 const infraStore = useInfraStore();
-if (infraStore.app_mode !== appMode.CLOUD) {
-  infraStore.create_backend();
+// In cloud mode, wait for the user to authenticate and load the app, unless a `?cloud_url=` link
+// Points at an already running service: that one is connected straight away, without authentication.
+if (infraStore.app_mode !== appMode.CLOUD || getCloudUrlParam() !== undefined) {
+  infraStore.create_backend(email);
 }
 
 function cloudCreateBackend(): Promise<void> {
diff --git a/app/stores/back.ts b/app/stores/back.ts
index d9b340aed..69987d195 100644
--- a/app/stores/back.ts
+++ b/app/stores/back.ts
@@ -29,12 +29,16 @@ export const useBackStore = defineStore("back", {
       return getRestApiPort(this.default_local_port);
     },
     base_url(): string {
-      const infraStore = useInfraStore();
-      let back_url = `${this.protocol}://${infraStore.domain_name}:${this.port}`;
-      if (isCloudMode()) {
-        back_url += `/geode`;
-      }
-      return back_url;
+      return this.base_url_for(useInfraStore().domain_name);
+    },
+    base_url_for(): (domain_name: string) => string {
+      return (domain_name: string) => {
+        let back_url = `${this.protocol}://${domain_name}:${this.port}`;
+        if (isCloudMode()) {
+          back_url += `/geode`;
+        }
+        return back_url;
+      };
     },
     is_busy(): boolean {
       return this.request_counter > 0;
diff --git a/app/stores/cloud.ts b/app/stores/cloud.ts
index dfbed975f..cbf49fc5c 100644
--- a/app/stores/cloud.ts
+++ b/app/stores/cloud.ts
@@ -1,6 +1,10 @@
+import { clearCloudUrlParam, getCloudUrlParam } from "@ogw_front/utils/cloud";
 import { Status } from "@ogw_front/utils/status";
+import { api_fetch } from "@ogw_internal/utils/api_fetch";
+import back_schemas from "@geode/opengeodeweb-back/opengeodeweb_back_schemas.json";
 import { setAppBaseUrl } from "@ogw_shared/scripts";
 import { useAPIStore } from "@ogw_front/stores/api";
+import { useFeedbackStore } from "@ogw_front/stores/feedback";
 
 const run_cloud_schema = {
   $id: "/cloud/run",
@@ -20,13 +24,24 @@ export const useCloudStore = defineStore("cloud", {
     status: Status.NOT_CONNECTED,
   }),
   actions: {
+    // Reuses the running service given by `?cloud_url=` when present, otherwise launches a new one.
+    // The param is single use: it is cleared whatever the outcome, so a retry launches a new service.
+    async start(email: string) {
+      const existing_host = getCloudUrlParam();
+      if (existing_host === undefined) {
+        await this.launch(email);
+        return;
+      }
+      try {
+        await this.connect_existing(existing_host);
+      } finally {
+        clearCloudUrlParam();
+      }
+    },
     async launch(email: string) {
       this.status = Status.CONNECTING;
       const { PROJECT, BRANCH } = useRuntimeConfig().public;
       const params = { email, project: PROJECT, branch: BRANCH };
-      const { useAppStore } = await import("./app");
-      const { useFeedbackStore } = await import("./feedback");
-      const appStore = useAppStore();
       const feedbackStore = useFeedbackStore();
       const APIStore = useAPIStore();
       const result = await APIStore.request(
@@ -45,18 +60,7 @@ export const useCloudStore = defineStore("cloud", {
             ) {
               return;
             }
-            const { url } = response;
-            feedbackStore.$patch({ server_error: false });
-            this.status = Status.CONNECTED;
-            const { useInfraStore } = await import("./infra");
-            const infraStore = useInfraStore();
-            infraStore.$patch({
-              domain_name: url,
-            });
-            setAppBaseUrl(appStore.base_url).catch(() => undefined);
-            appStore.$patch({
-              projectFolderPath: "/project",
-            });
+            await this.on_connected(response.url);
           },
           response_error_function: () => {
             feedbackStore.$patch({ server_error: true });
@@ -66,6 +70,46 @@ export const useCloudStore = defineStore("cloud", {
       );
       return result;
     },
+    async connect_existing(host: string) {
+      this.status = Status.CONNECTING;
+      const { useBackStore } = await import("./back");
+      const backStore = useBackStore();
+      // Probe the candidate host directly so domain_name is only updated once the service answers.
+      try {
+        await api_fetch(
+          {
+            $id: backStore.$id,
+            base_url: backStore.base_url_for(host),
+            start_request: () => {
+              backStore.start_request();
+            },
+            stop_request: () => {
+              backStore.stop_request();
+            },
+          },
+          { schema: back_schemas.opengeodeweb_back.ping },
+        );
+      } catch (error) {
+        useFeedbackStore().$patch({ server_error: true });
+        this.status = Status.NOT_CONNECTED;
+        throw error;
+      }
+      await this.on_connected(host);
+    },
+    async on_connected(url: string) {
+      const { useAppStore } = await import("./app");
+      const { useInfraStore } = await import("./infra");
+      const appStore = useAppStore();
+      useFeedbackStore().$patch({ server_error: false });
+      this.status = Status.CONNECTED;
+      useInfraStore().$patch({
+        domain_name: url,
+      });
+      appStore.$patch({
+        projectFolderPath: "/project",
+      });
+      await setAppBaseUrl(appStore.base_url);
+    },
     connect() {
       this.status = Status.CONNECTED;
     },
diff --git a/app/stores/infra.ts b/app/stores/infra.ts
index e42642b10..206b17a47 100644
--- a/app/stores/infra.ts
+++ b/app/stores/infra.ts
@@ -55,7 +55,13 @@ export const useInfraStore = defineStore("infra", {
         this.status = Status.CREATING;
         if (this.app_mode === appMode.CLOUD) {
           const cloudStore = useCloudStore();
-          await cloudStore.launch(email ?? "");
+          try {
+            await cloudStore.start(email ?? "");
+          } catch (error) {
+            // Back to the "Load the app" button so the user is not stuck on the loading screen.
+            this.status = Status.NOT_CREATED;
+            throw error;
+          }
         } else {
           const { useAppStore } = await import("@ogw_front/stores/app");
           const appStore = useAppStore();
diff --git a/app/utils/cloud.ts b/app/utils/cloud.ts
new file mode 100644
index 000000000..a55cbdd9f
--- /dev/null
+++ b/app/utils/cloud.ts
@@ -0,0 +1,35 @@
+const CLOUD_URL_PARAM = "cloud_url";
+const CLOUD_RUN_HOST_SUFFIX = ".run.app";
+
+// Hostname of an already running Cloud Run service passed as `?cloud_url=`, restricted to Cloud Run hosts so a crafted link cannot point the app at an arbitrary server.
+function getCloudUrlParam(): string | undefined {
+  const value = new URLSearchParams(globalThis.location.search).get(CLOUD_URL_PARAM);
+  if (value === null || value === "") {
+    return undefined;
+  }
+  const url_string = value.includes("://") ? value : `https://${value}`;
+  let hostname = "";
+  try {
+    ({ hostname } = new URL(url_string));
+  } catch {
+    console.warn(`[Cloud] Invalid ${CLOUD_URL_PARAM}:`, value);
+    return undefined;
+  }
+  if (!hostname.endsWith(CLOUD_RUN_HOST_SUFFIX)) {
+    console.warn(`[Cloud] Ignoring ${CLOUD_URL_PARAM}, not a Cloud Run host:`, hostname);
+    return undefined;
+  }
+  return hostname;
+}
+
+// Drops `?cloud_url=` from the address bar, keeping the router's history state, so a later "Load the app" launches a new service.
+function clearCloudUrlParam(): void {
+  const url = new URL(globalThis.location.href);
+  if (!url.searchParams.has(CLOUD_URL_PARAM)) {
+    return;
+  }
+  url.searchParams.delete(CLOUD_URL_PARAM);
+  globalThis.history.replaceState(globalThis.history.state, "", url);
+}
+
+export { clearCloudUrlParam, getCloudUrlParam };
diff --git a/tests/unit/stores/cloud.nuxt.test.ts b/tests/unit/stores/cloud.nuxt.test.ts
index 99d09fe7c..a18bf84bb 100644
--- a/tests/unit/stores/cloud.nuxt.test.ts
+++ b/tests/unit/stores/cloud.nuxt.test.ts
@@ -2,10 +2,11 @@
 // oxlint-disable vitest/require-mock-type-parameters
 // Third party imports
 import { $fetch, type FetchContext, type FetchResponse } from "ofetch";
-import { beforeEach, describe, expect, expectTypeOf, test, vi } from "vitest";
+import { afterEach, beforeEach, describe, expect, expectTypeOf, test, vi } from "vitest";
 
 // Local imports
 import { Status } from "@ogw_front/utils/status";
+import { appMode } from "@ogw_shared/app_mode";
 import { setupActivePinia } from "@ogw_tests/utils";
 import { useCloudStore } from "@ogw_front/stores/cloud";
 import { useFeedbackStore } from "@ogw_front/stores/feedback";
@@ -14,7 +15,11 @@ import { useInfraStore } from "@ogw_front/stores/infra";
 // A hand-built `$Fetch`: a mock function plus the `raw`/`native`/`create` members the real
 // `ofetch` export carries, so it satisfies the real type directly (no unsafe cast needed).
 vi.mock(import("ofetch"), () => ({
-  $fetch: Object.assign(vi.fn(), { raw: vi.fn(), native: vi.fn(), create: vi.fn() }),
+  $fetch: Object.assign(vi.fn(), {
+    raw: vi.fn(),
+    native: vi.fn(),
+    create: vi.fn(),
+  }),
 }));
 
 const mockedFetch = vi.mocked($fetch);
@@ -26,6 +31,12 @@ const CLOUD_API_URL = "https://api.example.com";
 const EMAIL = "noreply@example.com";
 const RESPONSE_OK_STATUS = 200;
 const RESPONSE_ERROR_STATUS = 500;
+const CLOUD_RUN_HOST = "vease-abc123.europe-west1.run.app";
+
+function setCloudUrlParam(value?: string): void {
+  const search = value === undefined ? "" : `?cloud_url=${encodeURIComponent(value)}`;
+  globalThis.history.replaceState(undefined, "", `/${search}`);
+}
 
 function setupConfig(): void {
   const config = useRuntimeConfig();
@@ -49,7 +60,9 @@ function buildFetchResponse<ResponseData>(
   responseData: ResponseData,
   status: number,
 ): FetchResponse<ResponseData> {
-  const response: FetchResponse<ResponseData> = Response.json(responseData, { status });
+  const response: FetchResponse<ResponseData> = Response.json(responseData, {
+    status,
+  });
   response._data = responseData;
   return response;
 }
@@ -121,7 +134,10 @@ describe("cloud store", () => {
         const cloudStore = useCloudStore();
         const feedbackStore = useFeedbackStore();
 
-        const error = createError({ statusCode: 500, statusMessage: "500 Internal Server Error" });
+        const error = createError({
+          statusCode: 500,
+          statusMessage: "500 Internal Server Error",
+        });
 
         mockedFetch.mockImplementation((_route, options) => {
           const onResponseErrorHooks = toHookArray(options?.onResponseError);
@@ -143,6 +159,130 @@ describe("cloud store", () => {
       });
     });
 
+    describe("connect_existing", () => {
+      beforeEach(() => {
+        mockedFetch.mockReset();
+        useInfraStore().app_mode = appMode.CLOUD;
+      });
+
+      test("successful connect_existing", async () => {
+        const cloudStore = useCloudStore();
+        const feedbackStore = useFeedbackStore();
+
+        mockedFetch.mockImplementation(async (_route, options) => {
+          const data = {};
+          const onResponseHooks = toHookArray(options?.onResponse);
+          await Promise.all(
+            onResponseHooks.map(async (hook) => {
+              await hook(buildFetchContext(data, RESPONSE_OK_STATUS));
+            }),
+          );
+          return data;
+        });
+
+        await cloudStore.connect_existing(CLOUD_RUN_HOST);
+
+        expect(mockedFetch).toHaveBeenCalledWith(
+          "opengeodeweb_back/ping",
+          expect.objectContaining({
+            baseURL: `https://${CLOUD_RUN_HOST}:443/geode`,
+          }),
+        );
+        expect(mockedFetch).not.toHaveBeenCalledWith("/cloud/run", expect.anything());
+        expect(cloudStore.status).toBe(Status.CONNECTED);
+        expect(feedbackStore.server_error).toBe(false);
+        expect(useInfraStore().domain_name).toBe(CLOUD_RUN_HOST);
+      });
+
+      test("failed connect_existing - unreachable service", async () => {
+        const cloudStore = useCloudStore();
+        const feedbackStore = useFeedbackStore();
+        const infraStore = useInfraStore();
+        const previous_domain_name = infraStore.domain_name;
+
+        const error = createError({
+          statusCode: 500,
+          statusMessage: "500 Internal Server Error",
+        });
+        mockedFetch.mockImplementation((_route, options) => {
+          const onResponseErrorHooks = toHookArray(options?.onResponseError);
+          for (const hook of onResponseErrorHooks) {
+            void hook(
+              buildFetchContext(
+                { name: "Error", description: "500 Internal Server Error" },
+                RESPONSE_ERROR_STATUS,
+              ),
+            );
+          }
+          throw error;
+        });
+
+        await expect(cloudStore.connect_existing(CLOUD_RUN_HOST)).rejects.toThrow(
+          "500 Internal Server Error",
+        );
+
+        expect(cloudStore.status).toBe(Status.NOT_CONNECTED);
+        expect(feedbackStore.server_error).toBe(true);
+        expect(infraStore.domain_name).toBe(previous_domain_name);
+      });
+    });
+
+    describe("start", () => {
+      beforeEach(() => {
+        mockedFetch.mockReset();
+        useInfraStore().app_mode = appMode.CLOUD;
+        mockedFetch.mockImplementation(async (_route, options) => {
+          const data = { url: "test.com" };
+          const onResponseHooks = toHookArray(options?.onResponse);
+          await Promise.all(
+            onResponseHooks.map(async (hook) => {
+              await hook(buildFetchContext(data, RESPONSE_OK_STATUS));
+            }),
+          );
+          return data;
+        });
+      });
+      afterEach(() => {
+        setCloudUrlParam();
+      });
+
+      test("without cloud_url launches a new service", async () => {
+        setupConfig();
+        setCloudUrlParam();
+        await useCloudStore().start(EMAIL);
+
+        expect(mockedFetch).toHaveBeenCalledWith("/cloud/run", expect.anything());
+        expect(useInfraStore().domain_name).toBe("test.com");
+      });
+
+      test("with cloud_url connects to the existing service", async () => {
+        setupConfig();
+        setCloudUrlParam(CLOUD_RUN_HOST);
+        await useCloudStore().start(EMAIL);
+
+        expect(mockedFetch).not.toHaveBeenCalledWith("/cloud/run", expect.anything());
+        expect(mockedFetch).toHaveBeenCalledWith("opengeodeweb_back/ping", expect.anything());
+        expect(useInfraStore().domain_name).toBe(CLOUD_RUN_HOST);
+        expect(globalThis.location.search).toBe("");
+      });
+
+      test("failed cloud_url is cleared so a retry launches a new service", async () => {
+        setupConfig();
+        setCloudUrlParam(CLOUD_RUN_HOST);
+        const cloudStore = useCloudStore();
+        mockedFetch.mockRejectedValueOnce(new Error("unreachable"));
+
+        await expect(cloudStore.start(EMAIL)).rejects.toThrow("unreachable");
+        expect(globalThis.location.search).toBe("");
+
+        mockedFetch.mockClear();
+        await cloudStore.start(EMAIL);
+        expect(mockedFetch).toHaveBeenCalledWith("/cloud/run", expect.anything());
+        expect(mockedFetch).not.toHaveBeenCalledWith("opengeodeweb_back/ping", expect.anything());
+        expect(useInfraStore().domain_name).toBe("test.com");
+      });
+    });
+
     describe("connect", () => {
       test("successful connect", () => {
         const cloudStore = useCloudStore();
diff --git a/tests/unit/stores/infra.nuxt.test.ts b/tests/unit/stores/infra.nuxt.test.ts
index 308af3849..885c2f123 100644
--- a/tests/unit/stores/infra.nuxt.test.ts
+++ b/tests/unit/stores/infra.nuxt.test.ts
@@ -271,5 +271,15 @@ describe("infra store", () => {
       expect(backStore.status).toBe(Status.NOT_CONNECTED);
       expect(viewerStore.status).toBe(Status.NOT_CONNECTED);
     });
+
+    test("cloud start failure resets status", async () => {
+      const infraStore = useInfraStore();
+
+      infraStore.app_mode = appMode.CLOUD;
+      vi.mocked($fetch).mockRejectedValue(new Error("unreachable"));
+
+      await expect(infraStore.create_backend("noreply@example.com")).rejects.toThrow("unreachable");
+      expect(infraStore.status).toBe(Status.NOT_CREATED);
+    });
   });
 });
diff --git a/tests/unit/utils/cloud.nuxt.test.ts b/tests/unit/utils/cloud.nuxt.test.ts
new file mode 100644
index 000000000..270670035
--- /dev/null
+++ b/tests/unit/utils/cloud.nuxt.test.ts
@@ -0,0 +1,62 @@
+// Third party imports
+import { afterEach, describe, expect, test } from "vitest";
+
+// Local imports
+import { clearCloudUrlParam, getCloudUrlParam } from "@ogw_front/utils/cloud";
+
+// CONSTANTS
+const CLOUD_RUN_HOST = "vease-abc123.europe-west1.run.app";
+
+function setCloudUrlParam(value?: string): void {
+  const search = value === undefined ? "" : `?cloud_url=${encodeURIComponent(value)}`;
+  globalThis.history.replaceState(undefined, "", `/${search}`);
+}
+
+describe("cloud_url query param parsing", () => {
+  afterEach(() => {
+    setCloudUrlParam();
+  });
+
+  test("missing", () => {
+    setCloudUrlParam();
+    expect(getCloudUrlParam()).toBeUndefined();
+  });
+
+  test("bare Cloud Run host", () => {
+    setCloudUrlParam(CLOUD_RUN_HOST);
+    expect(getCloudUrlParam()).toBe(CLOUD_RUN_HOST);
+  });
+
+  test("full Cloud Run URL", () => {
+    setCloudUrlParam(`https://${CLOUD_RUN_HOST}/some/path?query=1`);
+    expect(getCloudUrlParam()).toBe(CLOUD_RUN_HOST);
+  });
+
+  test("non Cloud Run host", () => {
+    setCloudUrlParam("evil.com");
+    expect(getCloudUrlParam()).toBeUndefined();
+  });
+
+  test("host only ending like Cloud Run", () => {
+    setCloudUrlParam("evilrun.app");
+    expect(getCloudUrlParam()).toBeUndefined();
+  });
+
+  test("invalid URL", () => {
+    setCloudUrlParam("https://");
+    expect(getCloudUrlParam()).toBeUndefined();
+  });
+});
+
+describe("cloud_url query param clearing", () => {
+  afterEach(() => {
+    setCloudUrlParam();
+  });
+
+  test("removes cloud_url and keeps other params", () => {
+    globalThis.history.replaceState(undefined, "", `/?foo=1&cloud_url=${CLOUD_RUN_HOST}`);
+    clearCloudUrlParam();
+    expect(globalThis.location.search).toBe("?foo=1");
+    expect(getCloudUrlParam()).toBeUndefined();
+  });
+});