diff --git a/src/codex/sync.ts b/src/codex/sync.ts
index 87b336eea62..b31a0859afc 100644
--- a/src/codex/sync.ts
+++ b/src/codex/sync.ts
@@ -132,6 +132,16 @@ export async function syncModelsToCodex(
   // the injector, before it gets a chance to create any artifact.
   const admission = (deps.admitCodexWrite ?? admitCodexWrite)();
   if (admission.kind === "refused" && admission.authority === "service-home") {
+    // Startup turns this result into a failed /readyz and records nothing else, and
+    // `ocx sync` only says the sync did not complete, so an unattended refusal must
+    // leave one line behind (#5782). The admission message can name private home and
+    // service-definition paths, so the log carries the authority only; POST /api/sync
+    // returns the specific reason to an authenticated operator.
+    log?.error(
+      "[opencodex] Codex write refused (service-home): this proxy could not prove it owns the "
+        + "installed service homes, so catalog sync and Codex config injection were skipped. "
+        + "POST /api/sync returns the specific reason.",
+    );
     return {
       status: "refused",
       authority: "service-home",
diff --git a/structure/config.md b/structure/config.md
index 79deb53630f..1ae6fc51842 100644
--- a/structure/config.md
+++ b/structure/config.md
@@ -270,6 +270,7 @@ missing on disk (presence only; a present key with another value is left alone).
 `ocx sync` and `ocx restore back` run the injector's non-writing preflight before provider
 discovery or catalog/cache replacement. Deterministic config and ownership refusals therefore
 leave the existing catalog and cache untouched, and their concrete messages are emitted on stderr.
+The earlier service-home admission refusal logs one path-free line; `POST /api/sync` returns its reason.
 Exactly one conversation-history refusal scopes the relabel unit instead of vetoing the apply
 transition, and only because it is permanent. Codex allocates paginated rollout ordinals inside
 its own writer, so `history_paginated_requires_native_writer` is not retryable: when the admitted
diff --git a/tests/codex-integration/codex-sync-api.test.ts b/tests/codex-integration/codex-sync-api.test.ts
index b19ef2ae55f..c632b6df225 100644
--- a/tests/codex-integration/codex-sync-api.test.ts
+++ b/tests/codex-integration/codex-sync-api.test.ts
@@ -165,6 +165,41 @@ describe("GUI/CLI Codex sync backend", () => {
     expect(errors).toEqual([]);
   });
 
+  test("a service-home refusal leaves one path-free log line and writes nothing (#5782)", async () => {
+    const privatePath = "/srv/private-operator/.opencodex";
+    const logs: string[] = [];
+    const errors: string[] = [];
+    let refreshed = false;
+    let injected = false;
+    const result = await syncModelsToCodex(12345, config, { log: line => logs.push(String(line)), error: line => errors.push(String(line)) }, {
+      admitCodexWrite: () => ({
+        kind: "refused" as const,
+        authority: "service-home" as const,
+        message: `Refusing to write: a service is installed for OPENCODEX_HOME=${privatePath}.`,
+      }),
+      refreshCodexModelCatalog: async () => {
+        refreshed = true;
+        throw new Error("must not refresh");
+      },
+      injectCodexConfig: async () => {
+        injected = true;
+        return { success: true, message: "must not inject" };
+      },
+      currentExternalCodexModelProvider: () => null,
+    });
+
+    expect(result.status).toBe("refused");
+    expect(result.ok).toBe(false);
+    expect(result.message).toContain(privatePath);
+    expect(refreshed).toBe(false);
+    expect(injected).toBe(false);
+    expect(logs).toEqual([]);
+    expect(errors).toHaveLength(1);
+    expect(errors[0]).toContain("service-home");
+    expect(errors[0]).toContain("POST /api/sync");
+    expect(errors[0]).not.toContain(privatePath);
+  });
+
   test("catalog sync proceeds after a bounded reasoning refresh fails on both sync paths", async () => {
     const calls: string[] = [];
     const routedConfig = {