diff --git a/agent/model_metadata.py b/agent/model_metadata.py
index ec75f7cfd90..4eba1ed89cd 100644
--- a/agent/model_metadata.py
+++ b/agent/model_metadata.py
@@ -1108,6 +1108,7 @@ _CODEX_OAUTH_CONTEXT_FALLBACK: Dict[str, int] = {
     "gpt-5.1-codex-max": 272_000,
     "gpt-5.1-codex-mini": 272_000,
     "gpt-5.3-codex": 272_000,
+    "gpt-5.3-codex-spark": 272_000,
     "gpt-5.2-codex": 272_000,
     "gpt-5.4-mini": 272_000,
     "gpt-5.5": 272_000,
diff --git a/tests/agent/test_model_metadata.py b/tests/agent/test_model_metadata.py
index 799390269b3..bd015083a8e 100644
--- a/tests/agent/test_model_metadata.py
+++ b/tests/agent/test_model_metadata.py
@@ -284,6 +284,7 @@ class TestCodexOAuthContextLength:
                 "gpt-5.4",
                 "gpt-5.4-mini",
                 "gpt-5.3-codex",
+                "gpt-5.3-codex-spark",
                 "gpt-5.2-codex",
                 "gpt-5.1-codex-max",
                 "gpt-5.1-codex-mini",