diff --git a/crates/provider/src/catalog.rs b/crates/provider/src/catalog.rs
index 049c4477..8ad7e4b8 100644
--- a/crates/provider/src/catalog.rs
+++ b/crates/provider/src/catalog.rs
@@ -442,17 +442,16 @@ mod tests {
     }
 
     #[test]
-    fn context_window_is_clamped_by_catalog_backend_max() {
+    fn codex_gpt55_catalog_records_effective_context_window() {
         let providers = load_builtin_providers().unwrap();
         let models = load_builtin_models().unwrap();
         let manifest = ModelManifest {
             ref_: Some("codex-oauth/gpt-5.5".into()),
-            context_window: Some(1_000_000),
             ..Default::default()
         };
         let cfg = resolve_with_catalogs(&manifest, &providers, &models).unwrap();
         assert_eq!(cfg.context_window, 272_000);
-        assert_eq!(cfg.max_context_window, Some(272_000));
+        assert_eq!(cfg.max_context_window, None);
     }
 
     #[test]
@@ -473,7 +472,7 @@ mod tests {
     }
 
     #[test]
-    fn manifest_backend_max_overrides_catalog_backend_max() {
+    fn manifest_backend_max_clamps_ref_context_override() {
         let providers = load_builtin_providers().unwrap();
         let models = load_builtin_models().unwrap();
         let manifest = ModelManifest {
diff --git a/resources/models/builtin.toml b/resources/models/builtin.toml
index a4fcf58b..8f92e20d 100644
--- a/resources/models/builtin.toml
+++ b/resources/models/builtin.toml
@@ -32,8 +32,10 @@ context_window = 256000
 [[model]]
 id = "gpt-5.5"
 provider = "codex-oauth"
-context_window = 1050000
-max_context_window = 272000
+# OpenAI docs advertise GPT-5.5 with a 1.05M context window, but Codex OAuth /
+# ChatGPT backend access is effectively limited around 272k tokens; this
+# provider-specific entry records that effective route limit directly.
+context_window = 272000
 capability = { tool_calling = "parallel", structured_output = "json_schema", reasoning = "effort", vision = true, prompt_caching = { kind = "auto" } }
 
 [[model]]