diff --git a/packages/effect-codex-app-server/src/_internal/shared.test.ts b/packages/effect-codex-app-server/src/_internal/shared.test.ts
index 5e87485c85d2..ba354d568701 100644
--- a/packages/effect-codex-app-server/src/_internal/shared.test.ts
+++ b/packages/effect-codex-app-server/src/_internal/shared.test.ts
@@ -3,6 +3,7 @@ import * as Effect from "effect/Effect";
 import * as Schema from "effect/Schema";
 
 import * as CodexError from "../errors.ts";
+import * as CodexSchema from "../schema.ts";
 import * as Shared from "./shared.ts";
 
 const decodeNestedNumberPayload = Schema.decodeUnknownEffect(
@@ -135,6 +136,47 @@ it.effect("passes request errors through without adding a wrapper", () =>
   }),
 );
 
+it.effect("normalizes unrecognized plan types to unknown before decoding", () =>
+  Effect.gen(function* () {
+    const account = yield* Shared.decodeOptionalPayload(
+      "account/read",
+      CodexSchema.V2GetAccountResponse,
+      {
+        account: {
+          type: "chatgpt",
+          email: "edu@example.com",
+          planType: "edu_plus",
+        },
+        requiresOpenaiAuth: false,
+      },
+    );
+
+    assert.deepEqual(account.account, {
+      type: "chatgpt",
+      email: "edu@example.com",
+      planType: "unknown",
+    });
+
+    const knownPlan = yield* Shared.decodeOptionalPayload(
+      "account/read",
+      CodexSchema.V2GetAccountResponse,
+      {
+        account: {
+          type: "chatgpt",
+          email: "plus@example.com",
+          planType: "plus",
+        },
+        requiresOpenaiAuth: false,
+      },
+    );
+
+    assert.equal(knownPlan.account?.type, "chatgpt");
+    if (knownPlan.account?.type === "chatgpt") {
+      assert.equal(knownPlan.account.planType, "plus");
+    }
+  }),
+);
+
 it.effect("retains the full notification payload decode cause chain", () =>
   Effect.gen(function* () {
     const error = yield* Shared.decodeNotificationPayload(
diff --git a/packages/effect-codex-app-server/src/_internal/shared.ts b/packages/effect-codex-app-server/src/_internal/shared.ts
index 34155348abfa..2fb916145259 100644
--- a/packages/effect-codex-app-server/src/_internal/shared.ts
+++ b/packages/effect-codex-app-server/src/_internal/shared.ts
@@ -17,6 +17,42 @@ export const JsonRpcResponseEnvelope = Schema.Struct({
   error: Schema.optional(JsonRpcError),
 });
 
+// Plan types emitted by the running codex binary can be newer than the pinned
+// protocol schema (e.g. "edu_plus"). Upstream maps unrecognized plans to
+// "unknown" via #[serde(other)]; mirror that so account payloads still decode.
+const KNOWN_PLAN_TYPES = new Set([
+  "free",
+  "go",
+  "plus",
+  "pro",
+  "prolite",
+  "team",
+  "self_serve_business_usage_based",
+  "business",
+  "enterprise_cbp_usage_based",
+  "enterprise",
+  "edu",
+  "unknown",
+]);
+
+export const normalizeUnknownPlanTypes = (value: unknown): unknown => {
+  if (Array.isArray(value)) {
+    return value.map(normalizeUnknownPlanTypes);
+  }
+  if (typeof value !== "object" || value === null) {
+    return value;
+  }
+
+  return Object.fromEntries(
+    Object.entries(value).map(([key, child]) => [
+      key,
+      key === "planType" && typeof child === "string" && !KNOWN_PLAN_TYPES.has(child)
+        ? "unknown"
+        : normalizeUnknownPlanTypes(child),
+    ]),
+  );
+};
+
 export const decodeOptionalPayload = <A, I>(
   method: string,
   schema: Schema.Codec<A, I> | undefined,
@@ -31,7 +67,9 @@ export const decodeOptionalPayload = <A, I>(
     );
   }
 
-  return Schema.decodeUnknownEffect(schema)(raw).pipe(
+  return Schema.decodeUnknownEffect(schema)(
+    typeof raw === "object" && raw !== null ? normalizeUnknownPlanTypes(raw) : raw,
+  ).pipe(
     Effect.mapError((error) =>
       CodexError.CodexAppServerRequestError.invalidPayload(method, "decode-payload", error),
     ),
diff --git a/packages/effect-codex-app-server/src/client.test.ts b/packages/effect-codex-app-server/src/client.test.ts
index 3830c5fc5f6f..1dfb495eaf5b 100644
--- a/packages/effect-codex-app-server/src/client.test.ts
+++ b/packages/effect-codex-app-server/src/client.test.ts
@@ -123,6 +123,37 @@ it.layer(NodeServices.layer)("effect-codex-app-server client", (it) => {
       ]);
     }),
   );
+  it.effect("decodes account plans the pinned protocol schema does not know", () =>
+    Effect.gen(function* () {
+      const handle = yield* makeHandle({
+        CODEX_APP_SERVER_TEST_ACCOUNT_PLAN_TYPE: "edu_plus",
+      });
+      const scope = yield* Scope.make();
+      const clientLayer = CodexClient.layerChildProcess(handle);
+      const context = yield* Layer.buildWithScope(clientLayer, scope);
+
+      const account = yield* Effect.gen(function* () {
+        const client = yield* CodexClient.CodexAppServerClient;
+        yield* client.request("initialize", {
+          clientInfo: {
+            name: "effect-codex-app-server-test",
+            title: "Effect Codex App Server Test",
+            version: "0.0.0",
+          },
+          capabilities: {
+            experimentalApi: true,
+            optOutNotificationMethods: null,
+          },
+        });
+        return yield* client.request("account/read", {});
+      }).pipe(Effect.provide(context), Effect.ensuring(Scope.close(scope, Exit.void)));
+
+      assert.equal(account.account?.type, "chatgpt");
+      if (account.account?.type === "chatgpt") {
+        assert.equal(account.account.planType, "unknown");
+      }
+    }),
+  );
   it.effect("drains child stderr so large diagnostics cannot block protocol responses", () =>
     Effect.gen(function* () {
       const handle = yield* makeHandle({
diff --git a/packages/effect-codex-app-server/test/fixtures/codex-app-server-mock-peer.ts b/packages/effect-codex-app-server/test/fixtures/codex-app-server-mock-peer.ts
index 3f2a213d38c7..a6f58f4df11c 100644
--- a/packages/effect-codex-app-server/test/fixtures/codex-app-server-mock-peer.ts
+++ b/packages/effect-codex-app-server/test/fixtures/codex-app-server-mock-peer.ts
@@ -71,11 +71,13 @@ const handleMethod = (message: Record<string, unknown>) => {
       return;
     }
     case "account/read": {
+      // oxlint-disable-next-line t3code/no-global-process-runtime -- Standalone mock peer process has no Effect runtime.
+      const planType = process.env.CODEX_APP_SERVER_TEST_ACCOUNT_PLAN_TYPE ?? "plus";
       respond(message.id as number | string, {
         account: {
           type: "chatgpt",
           email: "mock@example.com",
-          planType: "plus",
+          planType,
         },
         requiresOpenaiAuth: false,
       });