diff --git a/src/server/responses/collaboration.ts b/src/server/responses/collaboration.ts
index 0b28267ce..97620bfcb 100644
--- a/src/server/responses/collaboration.ts
+++ b/src/server/responses/collaboration.ts
@@ -249,10 +249,22 @@ export async function multiAgentGuidanceText(
     // Codex cannot actually spawn makes spawn_agent reject the override, so
     // suppress positive model claims while the state is stale or unknown.
     const catalogState = await (deps.collectCatalogState ?? defaultCollectCatalogState)();
-    if (catalogState.state === "stale" || catalogState.state === "unknown") {
+    if (catalogState.state === "stale") {
       return "<multi_agent_mode>The model catalog changed after Codex started; do not set "
         + "model or reasoning_effort overrides until Codex restarts.</multi_agent_mode>";
     }
+    // #1354: `unknown` is not `stale`. It means the comparison could not be made
+    // — the app-server start time or the catalog mtime was unreadable (a
+    // transient code-mode-host process exiting between enumeration and the
+    // start-time read is one way to land here). Suppressing overrides is still
+    // correct, but the stale text asserts a cause that was never established and
+    // prescribes a restart that cannot clear `unknown`. Mirror the honest
+    // phrasing `ocx doctor` already uses for this state.
+    if (catalogState.state === "unknown") {
+      return "<multi_agent_mode>Could not verify whether Codex's model catalog is current "
+        + "(app-server start time or catalog timestamp unreadable); do not set model or "
+        + "reasoning_effort overrides for this turn.</multi_agent_mode>";
+    }
     // codex-rs supplies the Proactive text on v2; the proxy only adds model-designation
     // guidance, and only when there is something concrete to designate: a configured
     // injectionModel and/or a roster entry that resolves in the injected catalog.
diff --git a/tests/multi-agent-compat.test.ts b/tests/multi-agent-compat.test.ts
index 8e9740cb1..bfdfd7465 100644
--- a/tests/multi-agent-compat.test.ts
+++ b/tests/multi-agent-compat.test.ts
@@ -143,6 +143,47 @@ describe("multiAgentGuidanceText", () => {
     }
   });
 
+  test("v2 guidance does not assert a catalog change or a restart remedy when the state is unknown (#1354)", async () => {
+    const dir = codexHomeFixture(V2_ON);
+    catalogFixture(dir, [{
+      slug: "anthropic/claude-sonnet-5",
+      efforts: ["low", "medium", "high", "xhigh"],
+    }]);
+    const parsed = parsedFixture({ reasoning: "medium", tools: [{ name: "spawn_agent" }] });
+    const options = { injectionModel: "anthropic/claude-sonnet-5" };
+
+    const stale = await multiAgentGuidanceText(parsed, options, {
+      collectCatalogState: () => ({ state: "stale" }),
+    });
+    const unknown = await multiAgentGuidanceText(parsed, options, {
+      collectCatalogState: () => ({ state: "unknown" }),
+    });
+
+    // "stale" is an established fact: the catalog really did change after the
+    // app-server started, and restarting Codex really does clear it.
+    expect(stale).toContain("The model catalog changed after Codex started");
+    expect(stale).toContain("until Codex restarts");
+
+    // "unknown" means the comparison could not be made at all — the process
+    // start time or the catalog mtime was unreadable. Neither the cause nor the
+    // remedy is established, and a restart cannot clear it, so the guidance must
+    // not assert either.
+    expect(unknown).not.toContain("The model catalog changed after Codex started");
+    expect(unknown).not.toContain("until Codex restarts");
+    expect(unknown).toContain("Could not verify");
+
+    // The suppression itself is correct in both states and must not regress:
+    // withhold the override instruction and any positive model claims.
+    for (const text of [stale, unknown]) {
+      expect(text).toContain("do not set");
+      expect(text).not.toContain("Preferred sub-agent");
+      expect(text).not.toContain("Available models");
+    }
+
+    // The two states must stay distinguishable to an operator reading the turn.
+    expect(unknown).not.toBe(stale);
+  });
+
   test("v2 built-in guidance is schema-agnostic and keeps fork rules", async () => {
     const dir = codexHomeFixture(V2_ON);
     catalogFixture(dir, [{