diff --git a/src/gateway/server-methods/agents-mutate.test.ts b/src/gateway/server-methods/agents-mutate.test.ts
index fb0ebdf10f36..87ae081db0a9 100644
--- a/src/gateway/server-methods/agents-mutate.test.ts
+++ b/src/gateway/server-methods/agents-mutate.test.ts
@@ -2947,19 +2947,36 @@ describe("agents.files.list", () => {
 
   // Pins the derivation: a private copy of this list in the gateway is what let a
   // retired file linger in the Control UI as a permanently-missing tab.
-  it("lists exactly the canonical workspace bootstrap filenames", async () => {
+  it("lists the canonical workspace filenames except IDENTITY.md", async () => {
     const names = await listAgentFileNames();
-    expect(names).toStrictEqual([...WORKSPACE_BOOTSTRAP_FILENAMES]);
+    expect(names).toStrictEqual(
+      WORKSPACE_BOOTSTRAP_FILENAMES.filter((name) => name !== "IDENTITY.md"),
+    );
   });
 
   it("lists the canonical filenames without BOOTSTRAP.md once setup completed", async () => {
     mocks.isWorkspaceSetupCompleted.mockResolvedValue(true);
     const names = await listAgentFileNames();
     expect(names).toStrictEqual(
-      WORKSPACE_BOOTSTRAP_FILENAMES.filter((name) => name !== "BOOTSTRAP.md"),
+      WORKSPACE_BOOTSTRAP_FILENAMES.filter(
+        (name) => name !== "IDENTITY.md" && name !== "BOOTSTRAP.md",
+      ),
     );
   });
 
+  // The identity form owns this file via agents.update; raw writes stay available
+  // so removing the editor tab does not remove the capability.
+  it("still accepts direct IDENTITY.md writes even though it is not listed", async () => {
+    const { respond, promise } = makeCall("agents.files.set", {
+      agentId: "main",
+      name: "IDENTITY.md",
+      content: "- Name: Ada\n",
+    });
+    await promise;
+
+    expectRespondOk(respond, { ok: true });
+  });
+
   it("rejects writes to retired HEARTBEAT.md workspace files", async () => {
     const { respond, promise } = makeCall("agents.files.set", {
       agentId: "main",
diff --git a/src/gateway/server-methods/agents.ts b/src/gateway/server-methods/agents.ts
index 604d947bc694..e899a05ed72c 100644
--- a/src/gateway/server-methods/agents.ts
+++ b/src/gateway/server-methods/agents.ts
@@ -101,7 +101,13 @@ import type { GatewayRequestHandlers, RespondFn } from "./types.js";
 
 // Derived from the canonical workspace list so retiring a bootstrap file cannot
 // leave the Control UI advertising a file the runtime no longer reads.
-const CORE_FILE_NAMES = WORKSPACE_BOOTSTRAP_FILENAMES;
+// IDENTITY.md is excluded: it is a parsed record that `agents.update` rewrites via
+// mergeIdentityMarkdownContent, so a second freeform editor would clobber fields
+// (Creature/Vibe, unfilled placeholders) that the identity form round-trips.
+// It stays writable through agents.files.set for clients that want raw access.
+const CORE_FILE_NAMES = WORKSPACE_BOOTSTRAP_FILENAMES.filter(
+  (name) => name !== DEFAULT_IDENTITY_FILENAME,
+);
 const CORE_FILE_NAMES_POST_ONBOARDING = CORE_FILE_NAMES.filter(
   (name) => name !== DEFAULT_BOOTSTRAP_FILENAME,
 );
@@ -131,8 +137,10 @@ export const testing = {
   },
 };
 
-// Gateway file mutations are intentionally capped to the workspace files the UI owns.
-const ALLOWED_FILE_NAMES = new Set<string>(CORE_FILE_NAMES);
+// Writes stay capped to canonical workspace files, and deliberately remain wider
+// than the listed core files: IDENTITY.md is not offered as an editor tab but is
+// still writable for clients that manage it directly.
+const ALLOWED_FILE_NAMES = new Set<string>(WORKSPACE_BOOTSTRAP_FILENAMES);
 
 function resolveAgentWorkspaceFileOrRespondError(
   params: Record<string, unknown>,