Enable remote compaction for Amazon Bedrock (#36981)

## What changed

- Add provider-owned remote compaction capabilities for unsupported, v1, and v2 protocols.
- Mark Amazon Bedrock as v1-only so manual and automatic compaction use `/v1/responses/compact`, even when the v2 feature is enabled.
- Preserve v2 support for OpenAI and Azure Responses providers and local compaction for unsupported providers.

## Testing

- Cover Amazon Bedrock manual and automatic remote compaction, including endpoint selection, authentication headers, model selection, and reuse of the compacted summary.

GitOrigin-RevId: d58093178605d1f8155b93d9a161408177f6ac72

codex-rs/model-provider/src/provider.rs

@@ -7,6 +7,7 @@ use std::sync::Arc;
 use codex_api::ApiError;
 use codex_api::Provider;
 use codex_api::SharedAuthProvider;
+use codex_api::is_azure_responses_provider;
 use codex_login::AuthManager;
 use codex_login::CodexAuth;
 use codex_model_provider_info::ModelProviderInfo;
@@ -25,6 +26,17 @@ use crate::auth::resolve_provider_auth;
 use crate::auth::resolve_provider_auth_for_scope;
 use crate::models_endpoint::OpenAiModelsEndpoint;
 
+/// Remote context-compaction protocols supported by a model provider.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum RemoteCompactionSupport {
+    /// The provider does not support remote compaction.
+    Unsupported,
+    /// The provider supports only the dedicated `/v1/responses/compact` endpoint.
+    V1,
+    /// The provider supports both the dedicated endpoint and `compaction_trigger` items.
+    V2,
+}
+
 /// Optional provider-backed features that Codex may expose at runtime.
 ///
 /// These capabilities are a provider-owned upper bound. Callers can disable
@@ -36,6 +48,7 @@ pub struct ProviderCapabilities {
     pub image_generation: bool,
     pub web_search: bool,
     pub external_web_access: bool,
+    pub remote_compaction: RemoteCompactionSupport,
 }
 
 impl Default for ProviderCapabilities {
@@ -45,6 +58,7 @@ impl Default for ProviderCapabilities {
             image_generation: true,
             web_search: true,
             external_web_access: true,
+            remote_compaction: RemoteCompactionSupport::V2,
         }
     }
 }
@@ -264,6 +278,21 @@ impl ModelProvider for ConfiguredModelProvider {
         &self.info
     }
 
+    fn capabilities(&self) -> ProviderCapabilities {
+        let remote_compaction = if self.info.is_openai()
+            || is_azure_responses_provider(&self.info.name, self.info.base_url.as_deref())
+        {
+            RemoteCompactionSupport::V2
+        } else {
+            RemoteCompactionSupport::Unsupported
+        };
+
+        ProviderCapabilities {
+            remote_compaction,
+            ..ProviderCapabilities::default()
+        }
+    }
+
     fn auth_manager(&self) -> Option<Arc<AuthManager>> {
         self.auth_manager.clone()
     }
@@ -508,6 +537,41 @@ mod tests {
         assert_eq!(provider.capabilities(), ProviderCapabilities::default());
     }
 
+    #[test]
+    fn configured_provider_remote_compaction_matches_provider_support() {
+        let cases = [
+            (
+                ModelProviderInfo::create_openai_provider(/*base_url*/ None),
+                RemoteCompactionSupport::V2,
+            ),
+            (
+                ModelProviderInfo {
+                    name: "Azure".to_string(),
+                    base_url: Some("https://example.com/openai".to_string()),
+                    ..ModelProviderInfo::default()
+                },
+                RemoteCompactionSupport::V2,
+            ),
+            (
+                ModelProviderInfo {
+                    name: "Custom".to_string(),
+                    base_url: Some("https://example.openai.azure.com/openai/v1".to_string()),
+                    ..ModelProviderInfo::default()
+                },
+                RemoteCompactionSupport::V2,
+            ),
+            (
+                provider_for("https://example.test/v1".to_string()),
+                RemoteCompactionSupport::Unsupported,
+            ),
+        ];
+
+        for (provider_info, expected) in cases {
+            let provider = create_model_provider(provider_info, /*auth_manager*/ None);
+            assert_eq!(provider.capabilities().remote_compaction, expected);
+        }
+    }
+
     #[test]
     fn configured_provider_uses_default_approval_review_preferred_model() {
         let provider = create_model_provider(