diff --git a/backend/crates/gateway-core/src/engine/coordinator.rs b/backend/crates/gateway-core/src/engine/coordinator.rs
index 449993b98..60bdb4efb 100644
--- a/backend/crates/gateway-core/src/engine/coordinator.rs
+++ b/backend/crates/gateway-core/src/engine/coordinator.rs
@@ -210,6 +210,8 @@ struct CurrentAttempt {
     index: NonZeroU32,
     started_at: SystemTime,
     send_observed: bool,
+    /// Provider 已为当前 attempt 交付可供同请求恢复的不透明状态检查点。
+    session_checkpoint_observed: bool,
     response_observation: Option<ProviderResponseObservation>,
 }
 
@@ -570,6 +572,9 @@ where
                     return Err(EngineError::Deadline);
                 }
                 PollBoundary::Item(Some(Ok(mut event))) => {
+                    if let Some(state) = event.session_update() {
+                        self.observe_session_checkpoint(state);
+                    }
                     if let Some(observation) = event.take_observation() {
                         self.observe_response(observation);
                     }
@@ -931,6 +936,7 @@ where
             index: next_attempt,
             started_at: SystemTime::now(),
             send_observed: false,
+            session_checkpoint_observed: false,
             response_observation: None,
         });
         Ok(None)
@@ -972,6 +978,17 @@ where
         self.mark_send_observed().await;
     }
 
+    fn observe_session_checkpoint(&mut self, state: &ProviderSessionState) {
+        let Some(current) = self.current.as_mut() else {
+            return;
+        };
+        if state.provider() != current.metadata.provider().as_str() {
+            return;
+        }
+        current.session_checkpoint_observed = true;
+        self.operation.set_provider_session_state(state.clone());
+    }
+
     async fn mark_send_observed(&mut self) {
         let Some(current) = self.current.as_mut() else {
             return;
@@ -1071,6 +1088,11 @@ where
             .await;
         }
         let provider_proved_replay_safe = provider_proved_replay_safe(&error);
+        // Ambiguous 仍是默认 fail-closed。唯一例外是 Provider 在同一 attempt 中先
+        // 交付了不透明恢复检查点，并明确证明从该检查点重放安全；该例外只用于
+        // 固定原账号的 transport recovery，不放开普通换号或 continuation 重放。
+        let checkpointed_transport_replay =
+            current.session_checkpoint_observed && error.replay_is_safe();
         let continuation_retry = self.prepare_continuation_retry(
             &current,
             &error,
@@ -1093,14 +1115,16 @@ where
                 delay,
             }) if self.downstream_committed_at.is_none()
                 && !self.delivery_pending
-                && attempt_send_state != UpstreamSendState::Ambiguous =>
+                && (attempt_send_state != UpstreamSendState::Ambiguous
+                    || checkpointed_transport_replay) =>
             {
                 Some((AttemptTransport::Retry(retry_index), delay))
             }
             Some(crate::error::PreDeliveryRetry::SameAccountTransportFallback)
                 if self.downstream_committed_at.is_none()
                     && !self.delivery_pending
-                    && attempt_send_state != UpstreamSendState::Ambiguous =>
+                    && (attempt_send_state != UpstreamSendState::Ambiguous
+                        || checkpointed_transport_replay) =>
             {
                 Some((AttemptTransport::Fallback, Duration::ZERO))
             }
diff --git a/backend/crates/gateway-core/src/error.rs b/backend/crates/gateway-core/src/error.rs
index d245030e4..ed810e1e5 100644
--- a/backend/crates/gateway-core/src/error.rs
+++ b/backend/crates/gateway-core/src/error.rs
@@ -623,13 +623,21 @@ impl ProviderError {
             .get_or_insert_with(|| Box::new(ProviderErrorFailureObservation::default()))
     }
 
-    /// 标记 Provider 已证明本次拒绝没有执行生成，可在下游提交前重放。
+    /// 标记 Provider 已证明本次失败可在下游提交前安全重放。
+    ///
+    /// 证明可以来自明确的“未执行”拒绝，也可以来自同 attempt 已交付、可恢复
+    /// 同一业务请求的状态检查点；后者仍须由 Core 的同账号恢复门禁单独校验。
     #[must_use]
     pub const fn with_replay_safe(mut self) -> Self {
         self.replay_safe = true;
         self
     }
 
+    /// 原地标记 Provider 已证明本次失败可从已交付的状态检查点安全恢复。
+    pub const fn set_replay_safe(&mut self) {
+        self.replay_safe = true;
+    }
+
     /// 允许 Core 仅在客户端尚未收到任何事件时执行一次受预算约束的换号恢复。
     ///
     /// 该标记不证明上游未执行，也不等价于 [`Self::with_replay_safe`]；它只表达
diff --git a/backend/crates/gateway-core/src/event.rs b/backend/crates/gateway-core/src/event.rs
index 768db7898..cc615d5b7 100644
--- a/backend/crates/gateway-core/src/event.rs
+++ b/backend/crates/gateway-core/src/event.rs
@@ -763,7 +763,8 @@ impl ProviderEvent {
         }
     }
 
-    /// 把本事件标记为 Provider 连接内状态的提交边界。
+    /// 附加 Provider 私有状态检查点；Core 可将其用于同请求恢复，协议连接可在
+    /// terminal 事件上持有它供下一轮使用。
     pub fn attach_session_update(&mut self, state: ProviderSessionState) {
         self.session_update = Some(Box::new(state));
     }
diff --git a/backend/crates/gateway-core/tests/engine/coordinator.rs b/backend/crates/gateway-core/tests/engine/coordinator.rs
index 7216c0165..79bcb379a 100644
--- a/backend/crates/gateway-core/tests/engine/coordinator.rs
+++ b/backend/crates/gateway-core/tests/engine/coordinator.rs
@@ -270,6 +270,7 @@ enum Script {
 struct ScriptedProvider {
     scripts: Mutex<VecDeque<Script>>,
     contexts: Mutex<Vec<AttemptContext>>,
+    operations: Mutex<Vec<Operation>>,
 }
 
 impl ScriptedProvider {
@@ -277,6 +278,7 @@ impl ScriptedProvider {
         Self {
             scripts: Mutex::new(scripts.into()),
             contexts: Mutex::new(Vec::new()),
+            operations: Mutex::new(Vec::new()),
         }
     }
 }
@@ -302,6 +304,10 @@ impl Provider for ScriptedProvider {
         request: ProviderRequest,
         context: AttemptContext,
     ) -> Result<ProviderStream, ProviderError> {
+        self.operations
+            .lock()
+            .expect("operations lock")
+            .push(request.operation().clone());
         self.contexts.lock().expect("contexts lock").push(context);
         let script = self
             .scripts
@@ -2838,14 +2844,25 @@ fn ambiguous_send_state_stops_retry() {
 fn ambiguous_pre_delivery_retry_marker_does_not_rotate_account() {
     let operation = generate_operation();
     let route_plan = plan(&operation);
+    let checkpoint = ProviderSessionState::new(
+        "openai",
+        Map::from_iter([("checkpoint".to_owned(), json!("opaque-state"))]),
+    )
+    .expect("provider checkpoint");
+    let mut checkpoint_event = ProviderEvent::observation(ProviderResponseObservation::new(
+        UpstreamTransport::new("websocket").expect("transport"),
+    ));
+    checkpoint_event.attach_session_update(checkpoint);
     let (coordinator, store, provider) = coordinator(vec![
-        Script::Stream {
+        Script::ObservedStream {
             account_id: "acct_first",
-            items: vec![Err(ProviderError::new(
-                ProviderErrorKind::Transport,
-                UpstreamSendState::Ambiguous,
-            )
-            .with_pre_delivery_retry())],
+            items: vec![
+                Ok(checkpoint_event),
+                Err(
+                    ProviderError::new(ProviderErrorKind::Transport, UpstreamSendState::Ambiguous)
+                        .with_pre_delivery_retry(),
+                ),
+            ],
         },
         Script::Stream {
             account_id: "acct_second",
@@ -2874,6 +2891,70 @@ fn ambiguous_pre_delivery_retry_marker_does_not_rotate_account() {
     assert_eq!(state.finalizations[0].outcome, ExecutionOutcome::Failed);
 }
 
+#[test]
+fn ambiguous_transport_retry_uses_provider_session_checkpoint_on_same_account() {
+    let operation = generate_operation();
+    let route_plan = plan(&operation);
+    let checkpoint = ProviderSessionState::new(
+        "openai",
+        Map::from_iter([("checkpoint".to_owned(), json!("opaque-state"))]),
+    )
+    .expect("provider checkpoint");
+    let mut checkpoint_event = ProviderEvent::observation(ProviderResponseObservation::new(
+        UpstreamTransport::new("websocket").expect("transport"),
+    ));
+    checkpoint_event.attach_session_update(checkpoint.clone());
+    let retry_index = NonZeroU32::new(1).expect("retry index");
+    let (coordinator, store, provider) = coordinator(vec![
+        Script::ObservedStream {
+            account_id: "acct_first",
+            items: vec![
+                Ok(checkpoint_event),
+                Err(
+                    ProviderError::new(ProviderErrorKind::Transport, UpstreamSendState::Ambiguous)
+                        .with_replay_safe()
+                        .with_pre_delivery_transport_retry(retry_index, Duration::ZERO),
+                ),
+            ],
+        },
+        Script::Stream {
+            account_id: "acct_first",
+            items: complete_stream(None),
+        },
+    ]);
+
+    let mut session = block_on(coordinator.start(
+        model_request(&operation, SystemTime::now() + Duration::from_secs(30)),
+        operation,
+        route_plan,
+        None,
+        None,
+        CancellationToken::new(),
+    ))
+    .expect("start execution");
+    block_on(session.collect_uncommitted()).expect("checkpointed retry succeeds");
+    block_on(session.commit_downstream(Some(200))).expect("commit winning response");
+
+    let original = ProviderAccountId::new("acct_first").expect("account id");
+    let contexts = provider.contexts.lock().expect("contexts lock");
+    assert_eq!(contexts.len(), 2);
+    assert_eq!(
+        contexts[1].transport(),
+        AttemptTransport::Retry(retry_index)
+    );
+    assert_eq!(contexts[1].required_account(), Some(&original));
+    drop(contexts);
+    let operations = provider.operations.lock().expect("operations lock");
+    assert_eq!(
+        operations[1].provider_session_state("openai"),
+        Some(&checkpoint)
+    );
+    let state = store.state.lock().expect("store lock");
+    assert_eq!(state.intermediate_failures, 1);
+    assert_eq!(state.finalizations[0].attempt_count, 2);
+    assert_eq!(state.finalizations[0].outcome, ExecutionOutcome::Succeeded);
+}
+
 #[test]
 fn pre_delivery_transport_fallback_retries_the_same_account_with_fallback_transport() {
     let operation = generate_operation();
diff --git a/backend/crates/providers/openai/src/provider/execution.rs b/backend/crates/providers/openai/src/provider/execution.rs
index 91461dd6a..c22c30ad4 100644
--- a/backend/crates/providers/openai/src/provider/execution.rs
+++ b/backend/crates/providers/openai/src/provider/execution.rs
@@ -186,6 +186,13 @@ pub(super) struct OpenAiSessionState {
     #[serde(default)]
     pub(super) client_turn_id: Option<String>,
     pub(super) continuation_scope: OpenAiContinuationScope,
+    /// 该状态来自同一业务请求的 metadata 检查点，只允许被紧随其后的恢复 attempt 消费。
+    #[serde(default, skip_serializing_if = "is_false")]
+    pub(super) retry_checkpoint: bool,
+}
+
+const fn is_false(value: &bool) -> bool {
+    !*value
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
@@ -232,6 +239,26 @@ pub(super) fn encode_openai_session_state(
         .map_err(|_| provider_error(ProviderErrorKind::Protocol, UpstreamSendState::Sent))
 }
 
+fn encode_openai_session_capture(
+    capture: &OpenAiSessionCapture,
+    retry_checkpoint: bool,
+) -> Result<ProviderSessionState, ProviderError> {
+    let Some(continuation_scope) = capture.continuation_scope else {
+        return Err(provider_error(
+            ProviderErrorKind::Protocol,
+            UpstreamSendState::Sent,
+        ));
+    };
+    encode_openai_session_state(OpenAiSessionState {
+        account_id: capture.account_id.clone(),
+        conversation_id: capture.conversation_id.clone(),
+        turn_state: capture.turn_state.clone(),
+        client_turn_id: capture.client_turn_id.clone(),
+        continuation_scope,
+        retry_checkpoint,
+    })
+}
+
 pub(super) fn attach_openai_session_update(
     events: &mut [ProviderEvent],
     capture: &mut Option<OpenAiSessionCapture>,
@@ -245,16 +272,7 @@ pub(super) fn attach_openai_session_update(
     let Some(capture) = capture.take() else {
         return;
     };
-    let Some(continuation_scope) = capture.continuation_scope else {
-        return;
-    };
-    let Ok(update) = encode_openai_session_state(OpenAiSessionState {
-        account_id: capture.account_id,
-        conversation_id: capture.conversation_id,
-        turn_state: capture.turn_state,
-        client_turn_id: capture.client_turn_id,
-        continuation_scope,
-    }) else {
+    let Ok(update) = encode_openai_session_capture(&capture, false) else {
         return;
     };
     events[terminal_index].attach_session_update(update);
@@ -563,6 +581,7 @@ pub(super) fn cold_response_stream(response: ColdResponse) -> EventStream {
                         WebSocketRecoveryContext {
                             policy,
                             requirement: request_transport_requirement,
+                            replay_checkpoint_available: false,
                             retry_count: websocket_retry_count,
                             max_retries: stream_max_retries,
                             request_id: context.request_id().as_str(),
@@ -594,6 +613,9 @@ pub(super) fn cold_response_stream(response: ColdResponse) -> EventStream {
             Err(failure.error)?;
             return;
         }
+        let mut turn_state_checkpoint_observed = response.transport
+            == CodexBackendTransport::WebSocket
+            && response.turn_state.is_some();
         if let Some(capture) = session_capture.as_mut() {
             capture.continuation_scope = Some(if capture.response_store {
                 OpenAiContinuationScope::Persisted
@@ -707,6 +729,49 @@ pub(super) fn cold_response_stream(response: ColdResponse) -> EventStream {
                     continue;
                 }
                 Err(mut failure) => {
+                    let updates = take_rate_limit_updates(rate_limit_updates.as_ref()).await;
+                    let rate_limits_changed = if updates.is_empty() {
+                        false
+                    } else {
+                        passive_quota_observation.observe(&updates);
+                        let update_headers = rate_limit_update_headers(&updates);
+                        observation_state.merge_rate_limit_headers(&update_headers)
+                    };
+                    let turn_state_merge = merge_turn_state_update(
+                        turn_state_updates.as_ref(),
+                        &mut session_capture,
+                        &mut observation_state,
+                    )
+                    .await;
+                    turn_state_checkpoint_observed |= turn_state_merge.is_some();
+                    let retry_checkpoint_update = if turn_state_checkpoint_observed
+                        && failure.websocket_checkpoint_retryable
+                    {
+                        session_capture
+                            .as_ref()
+                            .and_then(|capture| encode_openai_session_capture(capture, true).ok())
+                    } else {
+                        None
+                    };
+                    let mut observation_event = if rate_limits_changed
+                        || turn_state_merge.is_some()
+                        || retry_checkpoint_update.is_some()
+                    {
+                        observation_state
+                            .observation()
+                            .map(ProviderEvent::observation)
+                    } else {
+                        None
+                    };
+                    if let (Some(event), Some(update)) =
+                        (observation_event.as_mut(), retry_checkpoint_update)
+                    {
+                        event.attach_session_update(update);
+                    }
+                    let replay_checkpoint_available = observation_event
+                        .as_ref()
+                        .and_then(ProviderEvent::session_update)
+                        .is_some();
                     if failure.websocket_transport_retryable
                         && response_transport == CodexBackendTransport::WebSocket
                         && (matches!(
@@ -719,6 +784,7 @@ pub(super) fn cold_response_stream(response: ColdResponse) -> EventStream {
                             WebSocketRecoveryContext {
                                 policy: WebSocketFailurePolicy::Budgeted,
                                 requirement: request_transport_requirement,
+                                replay_checkpoint_available,
                                 retry_count: websocket_retry_count,
                                 max_retries: stream_max_retries,
                                 request_id: context.request_id().as_str(),
@@ -731,24 +797,8 @@ pub(super) fn cold_response_stream(response: ColdResponse) -> EventStream {
                             },
                         );
                     }
-                    let updates = take_rate_limit_updates(rate_limit_updates.as_ref()).await;
-                    let rate_limits_changed = if updates.is_empty() {
-                        false
-                    } else {
-                        passive_quota_observation.observe(&updates);
-                        let update_headers = rate_limit_update_headers(&updates);
-                        observation_state.merge_rate_limit_headers(&update_headers)
-                    };
-                    let turn_state_changed = merge_turn_state_update(
-                        turn_state_updates.as_ref(),
-                        &mut session_capture,
-                        &mut observation_state,
-                    )
-                    .await;
-                    if (rate_limits_changed || turn_state_changed)
-                        && let Some(observation) = observation_state.observation()
-                    {
-                        yield ProviderEvent::observation(observation);
+                    if let Some(event) = observation_event {
+                        yield event;
                     }
                     if allows_account_state_mutation {
                         synchronize_passive_quota(
@@ -772,12 +822,14 @@ pub(super) fn cold_response_stream(response: ColdResponse) -> EventStream {
                 passive_quota_observation.observe(&updates);
                 observation_state.merge_rate_limit_headers(&rate_limit_update_headers(&updates))
             };
-            let turn_state_changed = merge_turn_state_update(
+            let turn_state_merge = merge_turn_state_update(
                 turn_state_updates.as_ref(),
                 &mut session_capture,
                 &mut observation_state,
             )
             .await;
+            turn_state_checkpoint_observed |= turn_state_merge.is_some();
+            let turn_state_changed = turn_state_merge.unwrap_or(false);
             let first_event_changed =
                 observation_state.observe_stream_chunk(&chunk, output_started_at);
             let chunk_len = chunk.len();
@@ -959,7 +1011,8 @@ pub(super) fn cold_response_stream(response: ColdResponse) -> EventStream {
             &mut session_capture,
             &mut observation_state,
         )
-        .await;
+        .await
+        .unwrap_or(false);
         attach_openai_session_update(&mut events, &mut session_capture);
         let completed = events
             .iter()
@@ -1030,15 +1083,11 @@ async fn merge_turn_state_update(
     updates: Option<&CodexTurnStateUpdate>,
     session_capture: &mut Option<OpenAiSessionCapture>,
     observation_state: &mut OpenAiResponseObservationState,
-) -> bool {
-    let Some(updates) = updates else {
-        return false;
-    };
-    let Some(turn_state) = updates.lock().await.take() else {
-        return false;
-    };
+) -> Option<bool> {
+    let updates = updates?;
+    let turn_state = updates.lock().await.take()?;
     if let Some(capture) = session_capture.as_mut() {
         capture.turn_state = Some(turn_state.clone());
     }
-    observation_state.merge_client_header("x-codex-turn-state", &turn_state)
+    Some(observation_state.merge_client_header("x-codex-turn-state", &turn_state))
 }
diff --git a/backend/crates/providers/openai/src/provider/failure.rs b/backend/crates/providers/openai/src/provider/failure.rs
index 22c7eb35a..9289cc9a3 100644
--- a/backend/crates/providers/openai/src/provider/failure.rs
+++ b/backend/crates/providers/openai/src/provider/failure.rs
@@ -39,6 +39,8 @@ pub fn openai_failure_affects_account_score(error: &ProviderError) -> bool {
 pub(super) struct MappedProviderFailure {
     pub(super) error: ProviderError,
     pub(super) websocket_transport_retryable: bool,
+    /// 兼容少数链路在 metadata 后、终态前关闭；仅在捕获 turn-state 时允许安全恢复。
+    pub(super) websocket_checkpoint_retryable: bool,
     pub(super) account_failure: Option<CodexAccountFailure>,
     /// 原始上游错误描述，仅在凭据错误状态下持久化。
     pub(super) error_message: Option<String>,
@@ -54,6 +56,7 @@ impl MappedProviderFailure {
         Self {
             error,
             websocket_transport_retryable: false,
+            websocket_checkpoint_retryable: false,
             account_failure: None,
             error_message: None,
             cyber_policy_failure: false,
@@ -451,6 +454,8 @@ pub(super) enum WebSocketFailurePolicy {
 pub(super) struct WebSocketRecoveryContext<'a> {
     pub(super) policy: WebSocketFailurePolicy,
     pub(super) requirement: TransportRequirement,
+    /// 本 attempt 已从 metadata 捕获可恢复同一请求的 turn-state 检查点。
+    pub(super) replay_checkpoint_available: bool,
     pub(super) retry_count: u32,
     pub(super) max_retries: u32,
     pub(super) request_id: &'a str,
@@ -505,10 +510,11 @@ pub(super) fn apply_websocket_recovery_policy(
     context: WebSocketRecoveryContext<'_>,
 ) {
     let send_state = failure.error.send_state();
-    if matches!(
+    let post_send = matches!(
         send_state,
         UpstreamSendState::Sent | UpstreamSendState::Ambiguous
-    ) {
+    );
+    if post_send && !context.replay_checkpoint_available {
         // payload 已经发送或发送结果不确定时，代理不能用同一业务输入自动重放。
         // 当前请求保持终态失败；恢复状态只裁决客户端主动发起的下一次请求。
         let session_recovery_transition = match context.session_recovery_probe.take() {
@@ -555,6 +561,11 @@ pub(super) fn apply_websocket_recovery_policy(
     // 传输恢复必须保持原账号可调度；最终 HTTP attempt 若仍失败，再按真实 HTTP
     // 结果更新账号健康度，避免中间 WS 错误把同账号钉选提前冷却掉。
     failure.account_failure = None;
+    if post_send {
+        // Core 对 Ambiguous 默认仍然 fail-closed；只有同一 attempt 的 session
+        // checkpoint 与这个 Provider proof 同时存在时，才允许同账号传输恢复。
+        failure.error.set_replay_safe();
+    }
     let fallback_now = context.policy == WebSocketFailurePolicy::ImmediateFallback
         || context.retry_count >= context.max_retries;
     if !fallback_now {
@@ -583,6 +594,7 @@ pub(super) fn apply_websocket_recovery_policy(
             websocket_max_retries = context.max_retries,
             websocket_retry_delay_ms = u64::try_from(delay.as_millis()).unwrap_or(u64::MAX),
             transport_requirement = context.requirement.as_str(),
+            replay_checkpoint_available = context.replay_checkpoint_available,
             "OpenAI upstream WebSocket failed; retrying the same account"
         );
         return;
@@ -621,6 +633,7 @@ pub(super) fn apply_websocket_recovery_policy(
             WebSocketFailurePolicy::Budgeted => "retry_budget_exhausted",
             WebSocketFailurePolicy::ImmediateFallback => "upgrade_required",
         },
+        replay_checkpoint_available = context.replay_checkpoint_available,
         session_affinity_present = context.session_affinity_key.is_some(),
         session_affinity_key_hash = context.session_affinity_key_hash.unwrap_or(""),
         session_transport_action =
@@ -673,14 +686,31 @@ pub(super) fn continuation_replay_required_error(reason: &'static str) -> Provid
 pub(super) fn map_stream_error(error: CodexClientError) -> MappedProviderFailure {
     let allows_pre_delivery_retry = stream_transport_allows_pre_delivery_retry(&error);
     let websocket_failure = error.transport() == Some(CodexBackendTransport::WebSocket);
+    let websocket_checkpoint_retryable = websocket_metadata_close_can_resume(&error);
     let mut failure = map_client_error(error, UpstreamSendState::Sent, false);
     failure.websocket_transport_retryable = allows_pre_delivery_retry && websocket_failure;
+    failure.websocket_checkpoint_retryable =
+        allows_pre_delivery_retry && websocket_checkpoint_retryable;
     if allows_pre_delivery_retry && !websocket_failure {
         failure.error = failure.error.with_pre_delivery_retry();
     }
     failure
 }
 
+fn websocket_metadata_close_can_resume(error: &CodexClientError) -> bool {
+    let CodexClientError::WebSocket(error) = error else {
+        return false;
+    };
+    let Some(close) = error.close_before_terminal() else {
+        return false;
+    };
+    close.code() == Some(1000)
+        && matches!(
+            close.last_event_type(),
+            Some("codex.response.metadata" | "response.metadata")
+        )
+}
+
 pub(super) fn stream_transport_allows_pre_delivery_retry(error: &CodexClientError) -> bool {
     match error {
         CodexClientError::Http(_)
@@ -1068,6 +1098,7 @@ pub(super) fn map_upstream_failure(
     MappedProviderFailure {
         error,
         websocket_transport_retryable: false,
+        websocket_checkpoint_retryable: false,
         account_failure: account_failure(
             category,
             failure.retry_after_seconds,
diff --git a/backend/crates/providers/openai/src/provider/mod.rs b/backend/crates/providers/openai/src/provider/mod.rs
index 86acc684f..086609610 100644
--- a/backend/crates/providers/openai/src/provider/mod.rs
+++ b/backend/crates/providers/openai/src/provider/mod.rs
@@ -321,12 +321,14 @@ impl Provider for CodexProvider {
             identity.prepare_local_conversation(&mut upstream_request);
         }
         if let Some(previous_session) = previous_session.as_ref() {
-            upstream_request.turn_state = if same_client_turn(
-                previous_session.client_turn_id.as_deref(),
-                upstream_request.client_turn_id.as_deref(),
-            ) {
+            upstream_request.turn_state = if previous_session.retry_checkpoint
+                || same_client_turn(
+                    previous_session.client_turn_id.as_deref(),
+                    upstream_request.client_turn_id.as_deref(),
+                ) {
                 // 客户端可能携带 metadata-close 失败后才拿到的新状态；同一
-                // turn 内显式回传值比最后一次成功响应保存的状态更新。
+                // turn 内显式回传值比最后一次成功响应保存的状态更新。同请求
+                // 内部恢复由一次性 retry checkpoint 明确证明，不依赖客户端 turn ID。
                 upstream_request
                     .turn_state
                     .take()
diff --git a/backend/crates/providers/openai/tests/provider/contract.rs b/backend/crates/providers/openai/tests/provider/contract.rs
index fb13fa8b6..ecb2beeff 100644
--- a/backend/crates/providers/openai/tests/provider/contract.rs
+++ b/backend/crates/providers/openai/tests/provider/contract.rs
@@ -665,6 +665,7 @@ async fn capture_turn_state_request(
     previous_turn_id: Option<&str>,
     current_turn_id: Option<&str>,
     client_turn_state: Option<&str>,
+    retry_checkpoint: bool,
 ) -> wiremock::Request {
     let account_id = "acct_session_affinity";
     let store = Arc::new(MemoryAccountStore::default());
@@ -689,6 +690,9 @@ async fn capture_turn_state_request(
     if let Some(previous_turn_id) = previous_turn_id {
         session_state.insert("client_turn_id".to_owned(), json!(previous_turn_id));
     }
+    if retry_checkpoint {
+        session_state.insert("retry_checkpoint".to_owned(), json!(true));
+    }
     let mut protocol_context = Map::from_iter([("use_websocket".to_owned(), json!(false))]);
     if let Some(current_turn_id) = current_turn_id {
         protocol_context.insert("turn_id".to_owned(), json!(current_turn_id));
@@ -2521,7 +2525,7 @@ async fn websocket_turn_state_metadata_is_exposed_through_response_observation()
 }
 
 #[tokio::test]
-async fn websocket_turn_state_metadata_survives_close_1000_without_changing_failure_semantics() {
+async fn websocket_turn_state_metadata_close_requests_checkpointed_retry() {
     const ACCOUNT_ID: &str = "acct_websocket_metadata_close";
     const TURN_STATE: &str = "turn-state-before-close";
 
@@ -2579,6 +2583,7 @@ async fn websocket_turn_state_metadata_survives_close_1000_without_changing_fail
         .await
         .expect("prepare WebSocket provider stream");
     let mut observed_turn_state = false;
+    let mut replay_checkpoint = None;
     let error = loop {
         match stream.next().await {
             Some(Ok(event)) => {
@@ -2588,6 +2593,9 @@ async fn websocket_turn_state_metadata_survives_close_1000_without_changing_fail
                             && header.value().as_ref() == TURN_STATE.as_bytes()
                     });
                 }
+                if let Some(update) = event.session_update() {
+                    replay_checkpoint = Some(update.clone());
+                }
             }
             Some(Err(error)) => break error,
             None => panic!("metadata close must surface a provider error"),
@@ -2596,8 +2604,22 @@ async fn websocket_turn_state_metadata_survives_close_1000_without_changing_fail
     server.await.expect("WebSocket server");
 
     assert!(observed_turn_state);
+    let replay_checkpoint = replay_checkpoint.expect("metadata close checkpoint");
+    assert_eq!(
+        replay_checkpoint.payload().get("turn_state"),
+        Some(&json!(TURN_STATE))
+    );
+    assert_eq!(
+        replay_checkpoint.payload().get("retry_checkpoint"),
+        Some(&json!(true))
+    );
     assert_eq!(error.send_state(), UpstreamSendState::Ambiguous);
-    assert_eq!(error.pre_delivery_retry(), None);
+    assert!(error.replay_is_safe());
+    assert!(matches!(
+        error.pre_delivery_retry(),
+        Some(PreDeliveryRetry::SameAccountTransportRetry { retry_index, .. })
+            if retry_index.get() == 1
+    ));
     assert_eq!(
         error.upstream_code().map(|code| code.as_str()),
         Some("websocket_close_1000")
@@ -3036,6 +3058,7 @@ async fn matching_turn_id_should_restore_previous_turn_state() {
         Some("turn-same"),
         Some("turn-same"),
         None,
+        false,
     )
     .await;
 
@@ -3045,6 +3068,17 @@ async fn matching_turn_id_should_restore_previous_turn_state() {
     );
 }
 
+#[tokio::test]
+async fn retry_checkpoint_should_restore_turn_state_without_client_turn_id() {
+    let request =
+        capture_turn_state_request("req_restore_retry_checkpoint", None, None, None, true).await;
+
+    assert_eq!(
+        captured_header_values(&request, "x-codex-turn-state"),
+        vec![b"previous-turn-state".to_vec()]
+    );
+}
+
 #[tokio::test]
 async fn matching_turn_id_should_prefer_an_explicit_client_echo_over_saved_provider_state() {
     let request = capture_turn_state_request(
@@ -3052,6 +3086,7 @@ async fn matching_turn_id_should_prefer_an_explicit_client_echo_over_saved_provi
         Some("turn-same"),
         Some("turn-same"),
         Some("client-turn-state"),
+        false,
     )
     .await;
 
@@ -3083,6 +3118,7 @@ async fn new_or_unidentified_turn_should_not_restore_previous_turn_state() {
             previous_turn_id,
             current_turn_id,
             client_turn_state,
+            false,
         )
         .await;
         assert!(captured_header_values(&request, "x-codex-turn-state").is_empty());