diff --git a/docs-site/src/content/docs/reference/cli/lifecycle.md b/docs-site/src/content/docs/reference/cli/lifecycle.md
index 3473d3b19cc..68752d29f15 100644
--- a/docs-site/src/content/docs/reference/cli/lifecycle.md
+++ b/docs-site/src/content/docs/reference/cli/lifecycle.md
@@ -334,6 +334,8 @@ and this session ends with the app.
 Invalidate Codex's local model picker cache so it is rebuilt from the active opencodex catalog. The
 same stale-`app-server` warning and optional restart flags as `ocx sync` apply.
 
+If the derived cache already has identical bytes, the command succeeds without rewriting it or restarting Codex. With `--json`, this is reported as `ok: true`, `wrote: false`, `skipped: true`, and `skippedReason: "unchanged"`; an invalid catalog or failed cache write still exits nonzero.
+
 ### `ocx catalog pull <https-url> [--auth-env <NAME>] [--json] [--restart-codex] [--restart-app-server-only]`
 
 Install a complete catalog served by another OpenCodex instance's `/v1/catalog` endpoint, then
diff --git a/src/cli/dispatch.ts b/src/cli/dispatch.ts
index cea39a48d23..3600f5cc19d 100644
--- a/src/cli/dispatch.ts
+++ b/src/cli/dispatch.ts
@@ -547,21 +547,19 @@ const commandRunners: Record<string, CommandRunner> = {
     const cacheArgs = deps.args.slice(1);
     const restartScope = readRestartScope(cacheArgs, console);
     const { withCatalogWriteSerialization } = await import("../codex/catalog-write-serialization");
-    const { invalidateCodexModelsCacheWithPermit } = await import("../codex/catalog/sync");
+    const { invalidateCodexModelsCacheWithPermitOutcome } = await import("../codex/catalog/sync");
     const { getCodexHome } = await import("../codex/paths");
-    const { readCodexCatalogPathForHome } = await import("../codex/catalog/parsing");
-    const { existsSync } = await import("node:fs");
     const owningCodexHome = getCodexHome();
     const cacheGateSnapshot = deps.loadConfig();
     const desiredDisabled = !shouldSyncCodexOnStart(cacheGateSnapshot);
     const invalidated = withCatalogWriteSerialization(owningCodexHome, permit =>
-      invalidateCodexModelsCacheWithPermit(permit, owningCodexHome, { allowWhenDesiredDisabled: true }));
+      invalidateCodexModelsCacheWithPermitOutcome(permit, owningCodexHome, { allowWhenDesiredDisabled: true }));
     const cacheJson = cacheArgs.includes("--json");
     const jsonSafeLog = cacheJson
       ? { log: (...values: unknown[]) => console.error(...values), error: (...values: unknown[]) => console.error(...values) }
       : console;
     // Only warn/restart when models_cache was actually rewritten from a readable catalog.
-    if (invalidated.kind === "completed" && invalidated.value) {
+    if (invalidated.kind === "completed" && invalidated.value === "written") {
       await handleRestartScopeAfterWrite(restartScope, jsonSafeLog);
     } else if (desiredDisabled && !cacheJson) {
       // Worth saying in the human path, because it explains why nothing was written.
@@ -572,8 +570,8 @@ const commandRunners: Record<string, CommandRunner> = {
         "No catalog or cache write resulted.",
       ));
     }
-    // `completed` with a falsy value means the cache was NOT rewritten. Previously every
-    // outcome exited 0, so a script could not tell a refreshed cache from a skipped one.
+    // An identical cache is a successful no-op, not a failed refresh. Only a real write
+    // should restart Codex; a missing catalog or contended writer is also a benign skip.
     //
     // Losing the catalog write lock to another process is a skip, not a failure:
     // serialization working as designed is the expected outcome under concurrency, and a
@@ -588,30 +586,25 @@ const commandRunners: Record<string, CommandRunner> = {
     // means the user asked for it regardless of the toggle. Treating OFF as automatic success
     // would report exit 0 and `skipped: true` for a refresh that actually failed.
     //
-    // But `invalidateCodexModelsCacheWithPermit` returns a bare boolean for four different
-    // situations -- wrote it, no catalog file exists, the OFF gate fired, or it threw -- so
-    // `false` alone cannot be read as failure either. `!existsSync(catalogPath)` is a
-    // legitimate nothing-to-do: with no catalog there is no cache to derive, which is the
-    // normal state of a fully native home and the case
-    // `codex-composed-acceptance.test.ts` pins at exit 0. It is checked here rather than by
-    // widening that function's return type, because its boolean is consumed by a dozen
-    // management routes that have no use for the distinction.
-    const wrote = invalidated.kind === "completed" && Boolean(invalidated.value);
+    // The detailed outcome distinguishes an unchanged cache from a failed rewrite while
+    // the boolean wrapper remains available to callers that only care whether bytes changed.
+    const wrote = invalidated.kind === "completed" && invalidated.value === "written";
+    const unchanged = invalidated.kind === "completed" && invalidated.value === "unchanged";
     const contended = invalidated.kind === "unavailable" && invalidated.reason === "busy";
-    const noCatalog = !wrote && !existsSync(readCodexCatalogPathForHome(owningCodexHome));
-    const ok = wrote || contended || noCatalog;
+    const noCatalog = invalidated.kind === "completed" && invalidated.value === "missing_catalog";
+    const ok = wrote || unchanged || contended || noCatalog;
     if (cacheJson) {
       console.log(JSON.stringify({
         schemaVersion: 1,
         ok,
         wrote,
-        skipped: contended || noCatalog,
+        skipped: unchanged || contended || noCatalog,
         outcome: invalidated.kind,
         // `outcome` alone cannot separate a contended lock from a hard serialization
         // failure -- both are `unavailable`. Carry the reason so a caller can.
         reason: invalidated.kind === "unavailable" ? invalidated.reason : undefined,
         // Which of the two benign skips this was, so `skipped: true` is never opaque.
-        skippedReason: contended ? "contended" : noCatalog ? "no_catalog" : undefined,
+        skippedReason: unchanged ? "unchanged" : contended ? "contended" : noCatalog ? "no_catalog" : undefined,
         desiredDisabled,
         codexHome: owningCodexHome,
       }, null, 2));
@@ -619,6 +612,8 @@ const commandRunners: Record<string, CommandRunner> = {
       console.log("Another process owns the catalog write; cache sync skipped.");
     } else if (noCatalog) {
       console.log("No Codex catalog to derive a cache from; nothing to sync.");
+    } else if (unchanged) {
+      console.log("Codex model cache is already current; nothing to sync.");
     } else if (!ok) {
       console.error(`Cache refresh did not complete (${invalidated.kind}). The Codex model cache was not rewritten.`);
     }
diff --git a/src/codex/catalog/retained-sync.ts b/src/codex/catalog/retained-sync.ts
index efd3a63413e..aab9ebc205d 100644
--- a/src/codex/catalog/retained-sync.ts
+++ b/src/codex/catalog/retained-sync.ts
@@ -649,11 +649,13 @@ export async function syncCatalogModels(
   };
 }
 
-export function invalidateCodexModelsCacheWithPermit(
+export type CodexCacheInvalidationOutcome = "written" | "unchanged" | "missing_catalog" | "desired_disabled" | "failed";
+
+export function invalidateCodexModelsCacheWithPermitOutcome(
   permit: CatalogWritePermit,
   owningCodexHome: string,
   options?: CodexCatalogSyncOptions,
-): boolean {
+): CodexCacheInvalidationOutcome {
   try {
     // This permit is a REACQUISITION: refreshCodexModelCatalog's commit released
     // K before this rewrite runs, so the commit-path desired-state check cannot
@@ -661,9 +663,9 @@ export function invalidateCodexModelsCacheWithPermit(
     // routed cache write — re-read intent under this permit, same as the commit.
     // The catalog-only sync override applies here too so an explicit refresh
     // keeps the cache consistent with the catalog it just wrote.
-    if (!shouldSyncCodexOnStart(loadConfig()) && options?.allowWhenDesiredDisabled !== true) return false;
+    if (!shouldSyncCodexOnStart(loadConfig()) && options?.allowWhenDesiredDisabled !== true) return "desired_disabled";
     const catalogPath = readCodexCatalogPathForHome(owningCodexHome);
-    if (!existsSync(catalogPath)) return false;
+    if (!existsSync(catalogPath)) return "missing_catalog";
     const catalog = JSON.parse(readFileSync(catalogPath, "utf8"));
     const models = catalog.models ?? catalog;
     const cachePath = join(owningCodexHome, "models_cache.json");
@@ -711,14 +713,22 @@ export function invalidateCodexModelsCacheWithPermit(
     // `cacheSynced` mean what its name and its consumers already assume, and what
     // `pullRemoteCatalog` and the early returns in `refreshCodexModelCatalog`
     // already assert: a write happened.
-    if (!preparedBytesDifferFromDisk(preparedCache)) return false;
+    if (!preparedBytesDifferFromDisk(preparedCache)) return "unchanged";
     replaceCodexModelsCache(permit, owningCodexHome, preparedCache);
-    return true;
+    return "written";
   } catch {
-    return false;
+    return "failed";
   }
 }
 
+export function invalidateCodexModelsCacheWithPermit(
+  permit: CatalogWritePermit,
+  owningCodexHome: string,
+  options?: CodexCatalogSyncOptions,
+): boolean {
+  return invalidateCodexModelsCacheWithPermitOutcome(permit, owningCodexHome, options) === "written";
+}
+
 export function invalidateCodexModelsCache(options?: CodexCatalogSyncOptions): boolean {
   const owningCodexHome = getCodexHome();
   const outcome = withCatalogWriteSerialization(
diff --git a/src/codex/catalog/sync.ts b/src/codex/catalog/sync.ts
index 373bcb43779..83c233ef299 100644
--- a/src/codex/catalog/sync.ts
+++ b/src/codex/catalog/sync.ts
@@ -46,7 +46,7 @@ export {
 export {
   syncCatalogModels,
   invalidateCodexModelsCache,
-  invalidateCodexModelsCacheWithPermit,
+  invalidateCodexModelsCacheWithPermit, invalidateCodexModelsCacheWithPermitOutcome,
 } from "./retained-sync";
-export type { CodexCatalogSyncOptions } from "./retained-sync";
+export type { CodexCacheInvalidationOutcome, CodexCatalogSyncOptions } from "./retained-sync";
 export { restoreCodexCatalog, restoreCodexCatalogWithPermit } from "./restore";
diff --git a/structure/catalog.md b/structure/catalog.md
index 4379a35a891..16cd6cf782e 100644
--- a/structure/catalog.md
+++ b/structure/catalog.md
@@ -74,6 +74,8 @@ provider-wide fallback. Exact model output limits precede the provider default o
   native rows from the output without rewriting the pristine backup or unrelated snapshots;
 - invalidates `$CODEX_HOME/models_cache.json` when model visibility changes.
 
+Cache invalidation reports an unchanged derived cache separately from a failed rewrite. `ocx sync-cache` treats identical bytes as a successful no-op, preserving the cache mtime and avoiding a needless app-server restart; malformed catalogs and write failures remain errors.
+
 `src/codex/catalog/model-visibility.ts` also excludes models owned by disabled providers, including custom rows. `src/codex/catalog/routed-gather.ts` does not inherit provider configuration into custom rows while that provider is disabled.
 
 On the default `opencodex-catalog.json` path, sync deliberately uses two catalog sources: Codex's
diff --git a/tests/codex-integration/codex-app-server-processes.test.ts b/tests/codex-integration/codex-app-server-processes.test.ts
index 8f170d2f1ea..e36f91c22e0 100644
--- a/tests/codex-integration/codex-app-server-processes.test.ts
+++ b/tests/codex-integration/codex-app-server-processes.test.ts
@@ -823,8 +823,8 @@ describe("CLI /api sync wiring for stale app-servers (#476)", () => {
     // write actually landed, never on a refused/failed serialization attempt.
     expect(syncCacheCase).toContain("withCatalogWriteSerialization");
     // #1931: explicit sync-cache refreshes even when injection is OFF (side profiles).
-    expect(syncCacheCase).toContain("invalidateCodexModelsCacheWithPermit(permit, owningCodexHome, { allowWhenDesiredDisabled: true })");
-    const gate = 'if (invalidated.kind === "completed" && invalidated.value)';
+    expect(syncCacheCase).toContain("invalidateCodexModelsCacheWithPermitOutcome(permit, owningCodexHome, { allowWhenDesiredDisabled: true })");
+    const gate = 'if (invalidated.kind === "completed" && invalidated.value === "written")';
     expect(syncCacheCase).toContain(gate);
     expect(syncCacheCase).toContain("handleRestartScopeAfterWrite");
     expect(syncCacheCase.indexOf(gate))
diff --git a/tests/codex-integration/codex-composed-acceptance.test.ts b/tests/codex-integration/codex-composed-acceptance.test.ts
index 8274ca9be2f..31b0e9a5fa4 100644
--- a/tests/codex-integration/codex-composed-acceptance.test.ts
+++ b/tests/codex-integration/codex-composed-acceptance.test.ts
@@ -551,11 +551,15 @@ describe("WP13 composed toggle acceptance", () => {
         expect(result.exitCode).toBe(0);
         expect(manifest(fx.codex)).toEqual(before);
       }
-      for (const argv of [["sync"], ["sync-cache"]]) {
-        const result = await fx.runCli(argv);
-        expect(result.exitCode).toBe(0);
-        expect(manifestWithoutCatalogArtifacts(manifest(fx.codex))).toEqual(manifestWithoutCatalogArtifacts(before));
-      }
+      const synced = await fx.runCli(["sync"]);
+      expect(synced.exitCode).toBe(0);
+      expect(manifestWithoutCatalogArtifacts(manifest(fx.codex))).toEqual(manifestWithoutCatalogArtifacts(before));
+      const unchangedCache = await fx.runCli(["sync-cache", "--json"]);
+      expect(unchangedCache.exitCode).toBe(0);
+      expect(JSON.parse(unchangedCache.stdout)).toMatchObject({
+        ok: true, wrote: false, skipped: true, skippedReason: "unchanged", desiredDisabled: true,
+      });
+      expect(manifestWithoutCatalogArtifacts(manifest(fx.codex))).toEqual(manifestWithoutCatalogArtifacts(before));
       const sync = await fx.request(server.runtime, "/api/sync", { method: "POST" });
       expect(sync.status).toBe(200);
       expect(sync.body).toMatchObject({ status: "skipped", skippedReason: "desired_disabled", ok: true });
diff --git a/tests/codex-integration/codex-models-cache-invalidate.test.ts b/tests/codex-integration/codex-models-cache-invalidate.test.ts
index b644740e40e..c8264d50d0c 100644
--- a/tests/codex-integration/codex-models-cache-invalidate.test.ts
+++ b/tests/codex-integration/codex-models-cache-invalidate.test.ts
@@ -3,7 +3,7 @@ import { existsSync, mkdirSync, mkdtempSync, readFileSync, writeFileSync } from
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 import { invalidateCodexModelsCache } from "../../src/codex/catalog";
-import { invalidateCodexModelsCacheWithPermit } from "../../src/codex/catalog/sync";
+import { invalidateCodexModelsCacheWithPermit, invalidateCodexModelsCacheWithPermitOutcome } from "../../src/codex/catalog/sync";
 import { withCatalogWriteSerialization } from "../../src/codex/catalog-write-serialization";
 import {
   collectCodexAppServerCatalogStateForRequest,
@@ -64,6 +64,23 @@ describe("invalidateCodexModelsCache write gate (#476 / #518)", () => {
     expect(cache.models).toEqual([{ slug: "gpt-5.5" }]);
   });
 
+  test("distinguishes an unchanged cache from a failed refresh", () => {
+    writeFileSync(join(codexHome, "opencodex-catalog.json"), JSON.stringify({
+      models: [{ slug: "gpt-5.5" }],
+    }, null, 2) + "\n");
+    const invalidate = () => withCatalogWriteSerialization(codexHome, permit =>
+      invalidateCodexModelsCacheWithPermitOutcome(permit, codexHome));
+
+    expect(invalidate()).toMatchObject({ kind: "completed", value: "written" });
+    const cachePath = join(codexHome, "models_cache.json");
+    const before = readFileSync(cachePath);
+    expect(invalidate()).toMatchObject({ kind: "completed", value: "unchanged" });
+    expect(readFileSync(cachePath)).toEqual(before);
+
+    writeFileSync(join(codexHome, "opencodex-catalog.json"), "{ not-json");
+    expect(invalidate()).toMatchObject({ kind: "completed", value: "failed" });
+  });
+
   test("permit-bound invalidation stays on its owning home after ambient drift", () => {
     const ambientCodexHome = mkdtempSync(join(tmpdir(), "ocx-invalidate-ambient-"));
     try {