diff --git a/apps/api/src/app.ts b/apps/api/src/app.ts
index c2cd2675..e4a7239c 100644
--- a/apps/api/src/app.ts
+++ b/apps/api/src/app.ts
@@ -51,7 +51,6 @@ export const app = new Hono()
     if (isPublicCorsPath(c.req.path)) {
       c.set('user', null);
       c.set('session', null);
-      c.set('orgRoles', {});
 
       return next();
     }
@@ -67,7 +66,6 @@ export const app = new Hono()
     if (!session) {
       c.set('user', null);
       c.set('session', null);
-      c.set('orgRoles', {});
       await next();
 
       return;
@@ -75,7 +73,6 @@ export const app = new Hono()
 
     c.set('user', session.user);
     c.set('session', session.session);
-    c.set('orgRoles', (session as { orgRoles?: Record<string, number> }).orgRoles ?? {});
     await next();
   })
 
diff --git a/apps/api/src/middlewares/org-admin-or-automation-key.ts b/apps/api/src/middlewares/org-admin-or-automation-key.ts
index 615260c9..f1405fd9 100644
--- a/apps/api/src/middlewares/org-admin-or-automation-key.ts
+++ b/apps/api/src/middlewares/org-admin-or-automation-key.ts
@@ -3,6 +3,7 @@ import type { TOrganizationApiKeyScope } from '@cio/utils/validation/organizatio
 
 import { ErrorCodes } from '@api/utils/errors';
 import { ROLE } from '@cio/utils/constants';
+import { getOrgRolesForUser } from '@api/utils/redis/org-roles-cache';
 import { organizationApiKeyHasScopes } from '@api/services/organization/automation-key';
 
 export const orgAdminOrAutomationKeyMiddleware =
@@ -55,7 +56,7 @@ export const orgAdminOrAutomationKeyMiddleware =
         );
       }
 
-      const orgRoles = (c.get('orgRoles') as Record<string, number> | undefined) ?? {};
+      const orgRoles = await getOrgRolesForUser(user.id);
       if (orgRoles[orgId] !== ROLE.ADMIN) {
         return c.json(
           {
diff --git a/apps/api/src/middlewares/org-admin.ts b/apps/api/src/middlewares/org-admin.ts
index f5e50bb2..9fe86154 100644
--- a/apps/api/src/middlewares/org-admin.ts
+++ b/apps/api/src/middlewares/org-admin.ts
@@ -2,11 +2,11 @@ import { Context, Next } from 'hono';
 
 import { ErrorCodes } from '@api/utils/errors';
 import { ROLE } from '@cio/utils/constants';
+import { getOrgRolesForUser } from '@api/utils/redis/org-roles-cache';
 
 /**
  * Middleware to check if the authenticated user is an admin of the organization.
- * Reads the role from the Better Auth session (populated by the customSession plugin),
- * so no per-request DB query is performed.
+ * Reads `orgRoles` from the Redis-backed cache (DB fallback on miss).
  *
  * Requires authMiddleware to be applied first.
  * Expects orgId in the 'cio-org-id' header.
@@ -37,7 +37,7 @@ export const orgAdminMiddleware = async (c: Context, next: Next) => {
       );
     }
 
-    const orgRoles = (c.get('orgRoles') as Record<string, number> | undefined) ?? {};
+    const orgRoles = await getOrgRolesForUser(user.id);
     const roleId = orgRoles[orgId];
 
     if (roleId !== ROLE.ADMIN) {
diff --git a/apps/api/src/middlewares/org-member.ts b/apps/api/src/middlewares/org-member.ts
index 8b3e91c7..3ed66533 100644
--- a/apps/api/src/middlewares/org-member.ts
+++ b/apps/api/src/middlewares/org-member.ts
@@ -1,9 +1,11 @@
 import { Context, Next } from 'hono';
+import { getOrgRolesForUser } from '@api/utils/redis/org-roles-cache';
 
 /**
  * Middleware to check if the authenticated user is a member of the organization.
- * Reads the role from the Better Auth session (populated by the customSession plugin),
- * so no per-request DB query is performed.
+ * Loads `orgRoles` from the Redis-backed cache (DB fallback on miss) so the
+ * lookup stays out of the Better Auth session cookie — keeping that cookie
+ * small enough for the oauth-proxy redirect to fit in a Location header.
  *
  * Requires authMiddleware to be applied first.
  * Expects orgId in the 'cio-org-id' header.
@@ -35,7 +37,7 @@ export const orgMemberMiddleware = async (c: Context, next: Next) => {
       );
     }
 
-    const orgRoles = (c.get('orgRoles') as Record<string, number> | undefined) ?? {};
+    const orgRoles = await getOrgRolesForUser(user.id);
     const roleId = orgRoles[orgId];
 
     if (roleId === undefined) {
diff --git a/apps/api/src/types/auth.ts b/apps/api/src/types/auth.ts
index 8270767e..2fd1974e 100644
--- a/apps/api/src/types/auth.ts
+++ b/apps/api/src/types/auth.ts
@@ -6,7 +6,6 @@ export type AuthSession = {
     actorId: string | null;
     automationKey: TOrganizationApiKey | null;
     orgId: string | null;
-    orgRoles: Record<string, number>;
     session: typeof auth.$Infer.Session.session | null;
     user: typeof auth.$Infer.Session.user | null;
     userRole: number | null;
diff --git a/apps/api/src/utils/redis/org-roles-cache.ts b/apps/api/src/utils/redis/org-roles-cache.ts
new file mode 100644
index 00000000..7f863700
--- /dev/null
+++ b/apps/api/src/utils/redis/org-roles-cache.ts
@@ -0,0 +1,39 @@
+import { getUserOrgRolesMap } from '@cio/db/queries/organization';
+import { logRedisUnavailableOnce, redis } from './redis';
+
+const TTL_SECONDS = 60 * 60; // 1 hour, matches the prior cookieCache.maxAge.
+
+const cacheKey = (userId: string) => `org-roles:${userId}`;
+
+export async function getOrgRolesForUser(userId: string): Promise<Record<string, number>> {
+  try {
+    const cached = await redis.get(cacheKey(userId));
+    if (cached) {
+      try {
+        return JSON.parse(cached) as Record<string, number>;
+      } catch {
+        // Stale/corrupt entry — fall through to DB.
+      }
+    }
+  } catch (error) {
+    logRedisUnavailableOnce('Redis GET org-roles failed, falling back to DB', error);
+  }
+
+  const orgRoles = await getUserOrgRolesMap(userId);
+
+  try {
+    await redis.set(cacheKey(userId), JSON.stringify(orgRoles), { EX: TTL_SECONDS });
+  } catch (error) {
+    logRedisUnavailableOnce('Redis SET org-roles failed, cache disabled', error);
+  }
+
+  return orgRoles;
+}
+
+export async function invalidateOrgRolesCache(userId: string): Promise<void> {
+  try {
+    await redis.del(cacheKey(userId));
+  } catch (error) {
+    logRedisUnavailableOnce('Redis DEL org-roles failed, falling back to TTL', error);
+  }
+}
diff --git a/packages/db/src/auth.ts b/packages/db/src/auth.ts
index 6ccec09c..aca8dbff 100644
--- a/packages/db/src/auth.ts
+++ b/packages/db/src/auth.ts
@@ -6,11 +6,9 @@ import { sendChangeEmailConfirmation, sendVerificationEmail } from './auth/email
 
 import { betterAuth } from 'better-auth/minimal';
 import { createProfileHook } from './auth/hooks/create-profile';
-import { customSession } from 'better-auth/plugins/custom-session';
 import { db } from '@db/drizzle';
 import { drizzleAdapter } from 'better-auth/adapters/drizzle';
 import { config as emailAndPassword } from './auth/email-password';
-import { getUserOrgRolesMap } from './queries/organization/organization';
 import { loginLink } from './auth/plugins/login-link';
 import { oAuthProxy } from 'better-auth/plugins/oauth-proxy';
 import { resolveTrustedBrowserOrigin } from './utils';
@@ -121,20 +119,6 @@ export const auth: ReturnType<typeof betterAuth> = betterAuth({
       productionURL: CONSTANTS.BASE_URL
     }),
     loginLink(),
-    tokenExchange(),
-    // Attaches the user's org memberships ({ [orgId]: roleId }) to the session
-    // so org-scoped middlewares can authorize without a per-request DB query.
-    // Refreshes when the session cookie cache expires (see session.cookieCache.maxAge).
-    customSession(async ({ user, session }) => {
-      let orgRoles: Record<string, number> = {};
-      try {
-        if (user?.id) {
-          orgRoles = await getUserOrgRolesMap(user.id);
-        }
-      } catch (error) {
-        console.error('customSession: failed to load orgRoles', error);
-      }
-      return { user, session, orgRoles };
-    })
+    tokenExchange()
   ]
 });