diff --git a/packages/adapters/acpx-local/src/server/config-schema.ts b/packages/adapters/acpx-local/src/server/config-schema.ts
index 6e8dd9b6769..ca41aaacdef 100644
--- a/packages/adapters/acpx-local/src/server/config-schema.ts
+++ b/packages/adapters/acpx-local/src/server/config-schema.ts
@@ -54,6 +54,7 @@ export function getConfigSchema(): AdapterConfigSchema {
         type: "toggle",
         default: false,
         hint: "Only applies when ACP agent is Codex. Requests Codex Fast mode through ACP session config.",
+        meta: { visibleWhen: { key: "agent", values: ["codex"] } },
       },
       {
         key: "timeoutSec",
diff --git a/server/src/__tests__/adapter-routes.test.ts b/server/src/__tests__/adapter-routes.test.ts
index f06bf607513..06c25c7fb80 100644
--- a/server/src/__tests__/adapter-routes.test.ts
+++ b/server/src/__tests__/adapter-routes.test.ts
@@ -250,6 +250,7 @@ describe("adapter routes", () => {
         expect.objectContaining({
           key: "fastMode",
           default: false,
+          meta: { visibleWhen: { key: "agent", values: ["codex"] } },
         }),
         expect.objectContaining({
           key: "warmHandleIdleMs",