diff --git a/CHANGELOG.md b/CHANGELOG.md
index 883e762..1ff746f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,14 @@ All notable changes to netbox-super-cli are tracked here. Format follows [Keep a
 
 ## Unreleased
 
+### Fixed
+
+- **A `--schema`/`NSC_SCHEMA` override no longer leaks into later runs** ([#196]).
+  The override was saved as the profile's freshly fetched schema. So for the
+  next 24 hours (default `schema_refresh: daily`), and whenever NetBox was
+  unreachable, runs *without* the override silently used it. Overrides are now
+  never written to the profile's cache.
+
 ## v1.8.5 — 2026-10-23
 
 Patch release. `--schema` and `NSC_SCHEMA` report load failures clearly and behave the same way.
@@ -167,6 +175,7 @@ notices, and a fix for `nsc login` reporting the wrong user.
 [#186]: https://github.com/thomaschristory/netbox-super-cli/issues/186
 [#189]: https://github.com/thomaschristory/netbox-super-cli/issues/189
 [#192]: https://github.com/thomaschristory/netbox-super-cli/issues/192
+[#196]: https://github.com/thomaschristory/netbox-super-cli/issues/196
 [#171]: https://github.com/thomaschristory/netbox-super-cli/issues/171
 [#179]: https://github.com/thomaschristory/netbox-super-cli/issues/179
 [#173]: https://github.com/thomaschristory/netbox-super-cli/issues/173
diff --git a/docs/architecture/schema-loading.md b/docs/architecture/schema-loading.md
index 3b9735e..bc8be4a 100644
--- a/docs/architecture/schema-loading.md
+++ b/docs/architecture/schema-loading.md
@@ -9,7 +9,9 @@ and an optional `--refresh-schema` override:
 
 1. `--schema <path-or-url>` (or `NSC_SCHEMA`; the flag wins) — one-shot
    override. Always wins; never consults the TTL fast-path, the cache
-   fallback or the bundled snapshot. A missing file, unreachable URL or
+   fallback or the bundled snapshot. It never writes or refreshes the
+   profile's cache, so a later run without it can't pick it up; a cache
+   entry with the same hash (identical schema) is reused read-only. A missing file, unreachable URL or
    invalid document exits 3 with `cannot load schema from <source>: …`.
 2. **TTL fast-path.** If the policy is `daily`, `weekly`, or `manual` and
    the newest sidecar-validated cache entry for the active profile is
diff --git a/nsc/schema/source.py b/nsc/schema/source.py
index b885f2b..79b470e 100644
--- a/nsc/schema/source.py
+++ b/nsc/schema/source.py
@@ -1,7 +1,8 @@
 """Schema-source resolution chain.
 
 Order, given a `schema_refresh` policy and an optional `force_refresh`:
-  1. --schema flag (path or URL) — always wins, never consults TTL.
+  1. --schema flag / NSC_SCHEMA (path or URL) — always wins, never consults
+     TTL, and never writes the profile's cache (#196).
   2. TTL fast-path: if `schema_refresh` allows it and a cache entry for
      this profile is fresher than the policy's TTL, return it directly
      without any HTTP roundtrip. Skipped when `force_refresh=True`.
@@ -75,7 +76,7 @@ def resolve_command_model(
             )
         except SchemaLoadError as exc:
             raise SchemaSourceError(f"cannot load schema from {exc}") from exc
-        return _build_and_cache(loaded, paths, profile)
+        return _build_override(loaded, paths, profile)
 
     if not force_refresh:
         ttl = _ttl_for_policy(schema_refresh)
@@ -129,6 +130,20 @@ def _fetch_schema(url: str, profile: ResolvedProfile) -> LoadedSchema:
     return LoadedSchema(source=url, body=body, hash=canonical_sha256(body), document=document)
 
 
+def _build_override(loaded: LoadedSchema, paths: Paths, profile: ResolvedProfile) -> CommandModel:
+    """Issue #196: an override never writes or refreshes the profile's cache.
+    Persisting it (with a fresh `fetched_at`) let later runs without the
+    override serve it via the TTL fast-path or the offline fallback. A
+    same-hash entry is the identical schema, so reading it is safe."""
+    # ValueError: CacheStore rejects a profile name outside `_PROFILE_RE`;
+    # the override still works, just without the cache shortcut.
+    with contextlib.suppress(ValueError):
+        cached = CacheStore(root=paths.cache_dir).load(profile.name, loaded.hash)
+        if cached is not None:
+            return cached
+    return build_command_model(loaded)
+
+
 def _build_and_cache(loaded: LoadedSchema, paths: Paths, profile: ResolvedProfile) -> CommandModel:
     store = CacheStore(root=paths.cache_dir)
     cached = store.load(profile.name, loaded.hash)
diff --git a/tests/schema/test_source_ttl.py b/tests/schema/test_source_ttl.py
index f1b5559..1aa53c8 100644
--- a/tests/schema/test_source_ttl.py
+++ b/tests/schema/test_source_ttl.py
@@ -12,6 +12,7 @@
 from pathlib import Path
 from typing import Any
 
+import httpx2
 import pytest
 import respx
 
@@ -444,3 +445,73 @@ def test_aged_cache_with_unchanged_hash_refreshes_sidecar(
     assert route.call_count == 2, (
         "the second resolve refreshed the sidecar, so the third must use the fast path"
     )
+
+
+def _override_schema_doc() -> dict[str, Any]:
+    doc = _minimal_schema_doc()
+    doc["info"] = {"title": "override", "version": "9.9.9"}
+    return doc
+
+
+def _write_override(tmp_path: Path) -> str:
+    path = tmp_path / "override.json"
+    path.write_text(json.dumps(_override_schema_doc()), encoding="utf-8")
+    return str(path)
+
+
+def test_schema_override_does_not_satisfy_later_ttl_fast_path(
+    tmp_path: Path, httpx2_mock: respx.Router
+) -> None:
+    """#196: an override must not become the profile's fresh cache entry, or the
+    next run without it serves the override schema for the whole TTL window."""
+    route = httpx2_mock.get("https://nb.example/api/schema/?format=json").respond(
+        200, json=_minimal_schema_doc()
+    )
+    paths = _paths(tmp_path)
+    override = resolve_command_model(
+        paths=paths,
+        profile=_profile(),
+        schema_override=_write_override(tmp_path),
+        schema_refresh=SchemaRefresh.DAILY,
+    )
+    live = resolve_command_model(
+        paths=paths, profile=_profile(), schema_override=None, schema_refresh=SchemaRefresh.DAILY
+    )
+    assert route.call_count == 1
+    assert live.schema_hash != override.schema_hash
+
+
+def test_schema_override_is_not_served_by_offline_fallback(
+    tmp_path: Path, httpx2_mock: respx.Router
+) -> None:
+    httpx2_mock.get("https://nb.example/api/schema/?format=json").mock(
+        side_effect=httpx2.ConnectError("offline")
+    )
+    paths = _paths(tmp_path)
+    override = resolve_command_model(
+        paths=paths, profile=_profile(), schema_override=_write_override(tmp_path)
+    )
+    fallback = resolve_command_model(paths=paths, profile=_profile(), schema_override=None)
+    assert fallback.schema_hash != override.schema_hash
+
+
+@pytest.mark.httpx2(assert_all_called=False)
+def test_schema_override_reuses_matching_cache_entry_without_refreshing_it(
+    tmp_path: Path, httpx2_mock: respx.Router
+) -> None:
+    httpx2_mock.get("https://nb.example/api/schema/?format=json").respond(
+        200, json=_minimal_schema_doc()
+    )
+    paths = _paths(tmp_path)
+    live = resolve_command_model(paths=paths, profile=_profile(), schema_override=None)
+    profile_dir = paths.cache_dir / "prod"
+    stale = time.time() - 10 * 86_400
+    _age_sidecars(profile_dir, stale)
+    same = tmp_path / "same.json"
+    same.write_text(json.dumps(_minimal_schema_doc()), encoding="utf-8")
+
+    model = resolve_command_model(paths=paths, profile=_profile(), schema_override=str(same))
+
+    assert model.schema_hash == live.schema_hash
+    meta = json.loads((profile_dir / f"{live.schema_hash}.meta.json").read_text())
+    assert meta["fetched_at"] == stale