diff --git a/codex-rs/model-provider/src/amazon_bedrock/catalog.rs b/codex-rs/model-provider/src/amazon_bedrock/catalog.rs
index 6117a832bb..f7727363fc 100644
--- a/codex-rs/model-provider/src/amazon_bedrock/catalog.rs
+++ b/codex-rs/model-provider/src/amazon_bedrock/catalog.rs
@@ -79,6 +79,19 @@ pub(crate) fn static_model_catalog() -> ModelsResponse {
     })
 }
 
+pub(super) fn static_gov_model_catalog() -> ModelsResponse {
+    let mut catalog = static_model_catalog();
+    catalog.models.retain(|model| {
+        matches!(
+            model.slug.as_str(),
+            AMAZON_BEDROCK_GPT_5_6_TERRA_MODEL_ID
+                | AMAZON_BEDROCK_GPT_5_6_LUNA_MODEL_ID
+                | AMAZON_BEDROCK_GPT_5_4_MODEL_ID
+        )
+    });
+    catalog
+}
+
 pub(crate) fn normalize_bedrock_catalog(mut catalog: ModelsResponse) -> ModelsResponse {
     for model in &mut catalog.models {
         // Amazon Bedrock currently only supports the implicit "default" tier for GPT models.
diff --git a/codex-rs/model-provider/src/amazon_bedrock/mod.rs b/codex-rs/model-provider/src/amazon_bedrock/mod.rs
index e0e630def1..84c1d05a25 100644
--- a/codex-rs/model-provider/src/amazon_bedrock/mod.rs
+++ b/codex-rs/model-provider/src/amazon_bedrock/mod.rs
@@ -43,6 +43,7 @@ use crate::shared_state::process_shared_state;
 use auth::resolve_provider_auth as resolve_bedrock_provider_auth;
 pub(crate) use auth_refresh::AwsAuthRecovery;
 use catalog::normalize_bedrock_catalog;
+use catalog::static_gov_model_catalog;
 pub(crate) use catalog::static_model_catalog;
 pub(crate) use credential_export::AwsCredentialExport;
 use mantle::bedrock_mantle_runtime_base_url;
@@ -244,7 +245,25 @@ impl AmazonBedrockModelProvider {
 
     fn default_model_catalog(&self) -> ModelsResponse {
         match self.endpoint {
-            BedrockEndpoint::Mantle => static_model_catalog(),
+            BedrockEndpoint::Mantle => {
+                let endpoint = self
+                    .info
+                    .base_url
+                    .as_deref()
+                    .and_then(|base_url| url::Url::parse(base_url).ok());
+                let is_govcloud =
+                    endpoint
+                        .as_ref()
+                        .and_then(url::Url::host_str)
+                        .is_some_and(|host| {
+                            host.starts_with("bedrock-mantle.us-gov-") && host.ends_with(".api.aws")
+                        });
+                if is_govcloud {
+                    static_gov_model_catalog()
+                } else {
+                    static_model_catalog()
+                }
+            }
             BedrockEndpoint::Runtime => static_runtime_model_catalog(),
         }
     }
diff --git a/codex-rs/model-provider/src/provider.rs b/codex-rs/model-provider/src/provider.rs
index 1730e2a75b..acb7de1a75 100644
--- a/codex-rs/model-provider/src/provider.rs
+++ b/codex-rs/model-provider/src/provider.rs
@@ -1348,10 +1348,11 @@ printf '%s\n' '{"AccessKeyId":"exported","SecretAccessKey":"secret"}'
         assert!(!configured_model.additional_speed_tiers.is_empty());
         assert!(!configured_model.service_tiers.is_empty());
 
-        let provider = create_model_provider(
-            ModelProviderInfo::create_amazon_bedrock_provider(/*aws*/ None),
-            /*auth_manager*/ None,
-        );
+        let mut provider_info =
+            ModelProviderInfo::create_amazon_bedrock_provider(/*aws*/ None);
+        provider_info.base_url =
+            Some("https://bedrock-mantle.us-gov-west-1.api.aws/openai/v1".to_string());
+        let provider = create_model_provider(provider_info, /*auth_manager*/ None);
         let manager = provider.models_manager(
             test_codex_home(),
             Some(ModelsResponse {
diff --git a/codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__bedrock_govcloud_models.snap b/codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__bedrock_govcloud_models.snap
new file mode 100644
index 0000000000..49ac7903d2
--- /dev/null
+++ b/codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__bedrock_govcloud_models.snap
@@ -0,0 +1,12 @@
+---
+source: tui/src/chatwidget/tests/bedrock_catalog_tests.rs
+expression: "render_bottom_popup(&chat, 100)"
+---
+  Select Model and Effort
+
+
+› 1. GPT-5.6 Terra (current)  Older balanced model for straightforward work.
+  2. GPT-5.6 Luna             Older fast and efficient model.
+  3. GPT-5.4                  Strong model for everyday coding.
+
+  enter select · esc back
diff --git a/codex-rs/tui/src/chatwidget/tests/bedrock_catalog_tests.rs b/codex-rs/tui/src/chatwidget/tests/bedrock_catalog_tests.rs
index 5bcf9261b8..46e4a00f30 100644
--- a/codex-rs/tui/src/chatwidget/tests/bedrock_catalog_tests.rs
+++ b/codex-rs/tui/src/chatwidget/tests/bedrock_catalog_tests.rs
@@ -1,4 +1,4 @@
-//! Renders the provider catalog and Astra reasoning choices without changing the default model.
+//! Renders Bedrock provider catalogs and Astra reasoning choices.
 
 use super::*;
 use codex_http_client::HttpClientFactory;
@@ -51,3 +51,31 @@ async fn bedrock_astra_model_and_reasoning_pickers() {
         );
     }
 }
+
+#[tokio::test]
+async fn bedrock_govcloud_model_pickers() {
+    for region in ["us-gov-west-1", "us-gov-east-1"] {
+        let mut provider_info =
+            ModelProviderInfo::create_amazon_bedrock_provider(/*aws*/ None);
+        provider_info.base_url = Some(format!("https://bedrock-mantle.{region}.api.aws/openai/v1"));
+        let presets = create_model_provider(provider_info, /*auth_manager*/ None)
+            .models_manager_without_cache(/*config_model_catalog*/ None)
+            .list_models(
+                RefreshStrategy::Offline,
+                HttpClientFactory::new(OutboundProxyPolicy::ReqwestDefault),
+            )
+            .await;
+        let default_preset = presets
+            .iter()
+            .find(|preset| preset.is_default)
+            .expect("default Bedrock model");
+        let (mut chat, _events, _ops) = make_chatwidget_manual(Some(&default_preset.model)).await;
+        chat.thread_id = Some(ThreadId::new());
+        chat.model_catalog = Arc::new(ModelCatalog::new(presets));
+        chat.open_model_popup();
+        assert_chatwidget_snapshot!(
+            "bedrock_govcloud_models",
+            render_bottom_popup(&chat, /*width*/ 100)
+        );
+    }
+}