diff --git a/.github/pr-assets/5693-health-codex-harness.png b/.github/pr-assets/5693-health-codex-harness.png
new file mode 100644
index 0000000000..7f473e9b09
Binary files /dev/null and b/.github/pr-assets/5693-health-codex-harness.png differ
diff --git a/services/runner/src/version.ts b/services/runner/src/version.ts
index 185460f3fe..48fa7ec737 100644
--- a/services/runner/src/version.ts
+++ b/services/runner/src/version.ts
@@ -12,7 +12,7 @@ import pkg from "../package.json";
 export const PROTOCOL_VERSION = 1;
 export const RUNNER_VERSION: string = pkg.version;
 export const ENGINES = ["sandbox-agent"] as const;
-export const HARNESS_KINDS = ["pi_core", "claude", "pi_agenta"] as const;
+export const HARNESS_KINDS = ["pi_core", "claude", "pi_agenta", "codex"] as const;
 
 export interface RunnerInfo {
   status: "ok";
diff --git a/services/runner/tests/unit/version.test.ts b/services/runner/tests/unit/version.test.ts
new file mode 100644
index 0000000000..82b3b7ee88
--- /dev/null
+++ b/services/runner/tests/unit/version.test.ts
@@ -0,0 +1,27 @@
+/**
+ * Unit test for the runner's `/health` identity payload (`src/version.ts`).
+ *
+ * `HARNESS_KINDS` is a hardcoded list whose only consumer is `runnerInfo().harnesses` — nothing
+ * is gated on it, but a client probing `/health` uses it to learn what the runner supports. Codex
+ * became a harness of its own (its own model catalog, its own `CODEX_HOME` setup) without this
+ * list being extended, so `/health` under-reported it (#5693).
+ */
+import { describe, it } from "vitest";
+import assert from "node:assert/strict";
+
+import { HARNESS_KINDS, runnerInfo } from "../../src/version.ts";
+
+describe("HARNESS_KINDS", () => {
+  it("lists codex alongside the other harnesses the runner drives", () => {
+    assert.deepEqual(
+      [...HARNESS_KINDS].sort(),
+      ["claude", "codex", "pi_agenta", "pi_core"].sort(),
+    );
+  });
+});
+
+describe("runnerInfo", () => {
+  it("surfaces codex in the /health payload's harnesses list", () => {
+    assert.ok(runnerInfo().harnesses.includes("codex"));
+  });
+});