diff --git a/build/auth/idpLogout.d.ts b/build/auth/idpLogout.d.ts
new file mode 100644
index 0000000..83a1e07
--- /dev/null
+++ b/build/auth/idpLogout.d.ts
@@ -0,0 +1,19 @@
+/**
+ * Build the IDP (Gatekeeper) OIDC end-session URL for federated logout.
+ *
+ * Returns null unless every part is present, INCLUDING `idTokenHint`:
+ * Gatekeeper's end-session endpoint requires `id_token_hint` and rejects a
+ * request without it, so a caller that lacks the id token must fall back to a
+ * local-only sign-out rather than redirect the browser into a validation error.
+ */
+export interface IdpLogoutConfig {
+    /** IDP base URL, e.g. https://identity.omni.dev */
+    authBaseUrl?: string;
+    /** OAuth client id */
+    clientId?: string;
+    /** Post-logout redirect target (the app's own base URL) */
+    redirectUri?: string;
+    /** The user's id token; required by the end-session endpoint */
+    idTokenHint?: string;
+}
+export declare const buildIdpLogoutUrl: ({ authBaseUrl, clientId, redirectUri, idTokenHint, }: IdpLogoutConfig) => string | null;
diff --git a/build/auth/idpLogout.test.d.ts b/build/auth/idpLogout.test.d.ts
new file mode 100644
index 0000000..cb0ff5c
--- /dev/null
+++ b/build/auth/idpLogout.test.d.ts
@@ -0,0 +1 @@
+export {};
diff --git a/build/auth/index.d.ts b/build/auth/index.d.ts
index 2952863..98de9e9 100644
--- a/build/auth/index.d.ts
+++ b/build/auth/index.d.ts
@@ -2,6 +2,7 @@ export { createAuthCache } from "./cache";
 export { extractOrgClaims } from "./claims";
 export { GatekeeperOrgClient, GatekeeperOrgError, formatRelativeTime, getInviteTimeInfo, isInvitationExpired, validateInvitation, } from "./gatekeeperOrg";
 export { createGetAuth } from "./getAuth";
+export { buildIdpLogoutUrl } from "./idpLogout";
 export { verifyAccessToken } from "./jwt";
 export { createOmniOAuthConfig } from "./oauth";
 export { createOidcClient } from "./oidc";
@@ -11,6 +12,7 @@ export { OMNI_CLAIMS_NAMESPACE } from "./types";
 export type { AuthCache, AuthCacheConfig, CachedAuthData } from "./cache";
 export type { GatekeeperInvitation, GatekeeperMember, GatekeeperMemberRole, GatekeeperOrganization, InvitationValidationResult, InviteTimeInfo, ValidateInvitationParams, } from "./gatekeeperOrg";
 export type { BetterAuthApi, GetAuthConfig, GetAuthSession, ResolveRowIdFn, ResolveRowIdParams, SetCookieFn, } from "./getAuth";
+export type { IdpLogoutConfig } from "./idpLogout";
 export type { VerifyAccessTokenConfig } from "./jwt";
 export type { OmniOAuthConfig } from "./oauth";
 export type { OidcClient, OidcClientConfig, OidcDiscovery, } from "./oidc";
diff --git a/build/auth/index.js b/build/auth/index.js
index f5bfeeb..1eb64bb 100644
--- a/build/auth/index.js
+++ b/build/auth/index.js
@@ -3400,6 +3400,21 @@ function createGetAuth(config) {
     }
   };
 }
+// src/auth/idpLogout.ts
+var buildIdpLogoutUrl = ({
+  authBaseUrl,
+  clientId,
+  redirectUri,
+  idTokenHint
+}) => {
+  if (!authBaseUrl || !clientId || !redirectUri || !idTokenHint)
+    return null;
+  const url = new URL(`${authBaseUrl}/oauth2/end-session`);
+  url.searchParams.set("client_id", clientId);
+  url.searchParams.set("post_logout_redirect_uri", redirectUri);
+  url.searchParams.set("id_token_hint", idTokenHint);
+  return url.toString();
+};
 
 // src/auth/index.ts
 init_jwt();
@@ -3422,6 +3437,7 @@ function createOmniOAuthConfig(config) {
     ],
     accessType: "offline",
     pkce: true,
+    authorizationUrlParams: (ctx) => ctx.body?.additionalData?.screen_hint === "signup" ? { prompt: "create" } : {},
     mapProfileToUser: (profile) => ({
       name: profile.name,
       email: profile.email,
@@ -3542,6 +3558,7 @@ export {
   createOidcClient,
   createGetAuth,
   createAuthCache,
+  buildIdpLogoutUrl,
   OMNI_CLAIMS_NAMESPACE,
   GatekeeperOrgError,
   GatekeeperOrgClient
diff --git a/build/auth/oauth.d.ts b/build/auth/oauth.d.ts
index 25db707..11001bd 100644
--- a/build/auth/oauth.d.ts
+++ b/build/auth/oauth.d.ts
@@ -35,6 +35,13 @@ declare function createOmniOAuthConfig(config: OmniOAuthConfig): {
     scopes: string[];
     accessType: "offline";
     pkce: boolean;
+    authorizationUrlParams: (ctx: {
+        body?: {
+            additionalData?: {
+                screen_hint?: string;
+            };
+        };
+    }) => Record<string, string>;
     mapProfileToUser: (profile: Record<string, unknown>) => {
         name: string;
         email: string;
diff --git a/build/index.js b/build/index.js
index caeb51e..dc7bbdb 100644
--- a/build/index.js
+++ b/build/index.js
@@ -78035,6 +78035,7 @@ function createOmniOAuthConfig(config) {
     ],
     accessType: "offline",
     pkce: true,
+    authorizationUrlParams: (ctx) => ctx.body?.additionalData?.screen_hint === "signup" ? { prompt: "create" } : {},
     mapProfileToUser: (profile) => ({
       name: profile.name,
       email: profile.email,
diff --git a/src/auth/idpLogout.test.ts b/src/auth/idpLogout.test.ts
new file mode 100644
index 0000000..74ac8cc
--- /dev/null
+++ b/src/auth/idpLogout.test.ts
@@ -0,0 +1,47 @@
+import { describe, expect, it } from "bun:test";
+
+import { buildIdpLogoutUrl } from "./idpLogout";
+
+const full = {
+  authBaseUrl: "https://identity.example.com",
+  clientId: "client-123",
+  redirectUri: "https://app.example.com",
+  idTokenHint: "the-id-token",
+};
+
+describe("buildIdpLogoutUrl", () => {
+  it("builds the end-session url with all params when everything is present", () => {
+    const url = new URL(buildIdpLogoutUrl(full) as string);
+    expect(url.origin + url.pathname).toBe(
+      "https://identity.example.com/oauth2/end-session",
+    );
+    expect(url.searchParams.get("client_id")).toBe("client-123");
+    expect(url.searchParams.get("post_logout_redirect_uri")).toBe(
+      "https://app.example.com",
+    );
+    expect(url.searchParams.get("id_token_hint")).toBe("the-id-token");
+  });
+
+  it("returns null without an id token (the endpoint requires it)", () => {
+    expect(buildIdpLogoutUrl({ ...full, idTokenHint: undefined })).toBeNull();
+    expect(buildIdpLogoutUrl({ ...full, idTokenHint: "" })).toBeNull();
+  });
+
+  it("returns null when any IDP config part is missing", () => {
+    expect(buildIdpLogoutUrl({ ...full, authBaseUrl: undefined })).toBeNull();
+    expect(buildIdpLogoutUrl({ ...full, clientId: undefined })).toBeNull();
+    expect(buildIdpLogoutUrl({ ...full, redirectUri: undefined })).toBeNull();
+  });
+
+  it("url-encodes the id token and redirect uri", () => {
+    const url = buildIdpLogoutUrl({
+      ...full,
+      idTokenHint: "a b+c/d=",
+      redirectUri: "https://app.example.com/back?x=1",
+    }) as string;
+    expect(url).toContain("id_token_hint=a+b%2Bc%2Fd%3D");
+    expect(url).toContain(
+      "post_logout_redirect_uri=https%3A%2F%2Fapp.example.com%2Fback%3Fx%3D1",
+    );
+  });
+});
diff --git a/src/auth/idpLogout.ts b/src/auth/idpLogout.ts
new file mode 100644
index 0000000..c29d9f6
--- /dev/null
+++ b/src/auth/idpLogout.ts
@@ -0,0 +1,34 @@
+/**
+ * Build the IDP (Gatekeeper) OIDC end-session URL for federated logout.
+ *
+ * Returns null unless every part is present, INCLUDING `idTokenHint`:
+ * Gatekeeper's end-session endpoint requires `id_token_hint` and rejects a
+ * request without it, so a caller that lacks the id token must fall back to a
+ * local-only sign-out rather than redirect the browser into a validation error.
+ */
+export interface IdpLogoutConfig {
+  /** IDP base URL, e.g. https://identity.omni.dev */
+  authBaseUrl?: string;
+  /** OAuth client id */
+  clientId?: string;
+  /** Post-logout redirect target (the app's own base URL) */
+  redirectUri?: string;
+  /** The user's id token; required by the end-session endpoint */
+  idTokenHint?: string;
+}
+
+export const buildIdpLogoutUrl = ({
+  authBaseUrl,
+  clientId,
+  redirectUri,
+  idTokenHint,
+}: IdpLogoutConfig): string | null => {
+  if (!authBaseUrl || !clientId || !redirectUri || !idTokenHint) return null;
+
+  const url = new URL(`${authBaseUrl}/oauth2/end-session`);
+  url.searchParams.set("client_id", clientId);
+  url.searchParams.set("post_logout_redirect_uri", redirectUri);
+  url.searchParams.set("id_token_hint", idTokenHint);
+
+  return url.toString();
+};
diff --git a/src/auth/index.ts b/src/auth/index.ts
index a6067c7..c272df7 100644
--- a/src/auth/index.ts
+++ b/src/auth/index.ts
@@ -9,6 +9,7 @@ export {
   validateInvitation,
 } from "./gatekeeperOrg";
 export { createGetAuth } from "./getAuth";
+export { buildIdpLogoutUrl } from "./idpLogout";
 export { verifyAccessToken } from "./jwt";
 export { createOmniOAuthConfig } from "./oauth";
 export { createOidcClient } from "./oidc";
@@ -38,6 +39,7 @@ export type {
   ResolveRowIdParams,
   SetCookieFn,
 } from "./getAuth";
+export type { IdpLogoutConfig } from "./idpLogout";
 export type { VerifyAccessTokenConfig } from "./jwt";
 export type { OmniOAuthConfig } from "./oauth";
 export type {