core: generate context diffs after pre-turn compaction

codex-rs/core/src/codex.rs

@@ -3418,25 +3418,12 @@ mod handlers {
         // Attempt to inject input into current task.
         if let Err(SteerInputError::NoActiveTurn(items)) = sess.steer_input(items, None).await {
             sess.seed_initial_context_if_needed(&current_context).await;
-            let previous_model = sess.previous_model().await;
-            let previous_context_item = sess.previous_context_item().await;
-            let update_items = sess.build_settings_update_items(
-                previous_context_item.as_ref(),
-                previous_model.as_deref(),
-                &current_context,
-            );
-            if !update_items.is_empty() {
-                sess.record_conversation_items(&current_context, &update_items)
-                    .await;
-            }
 
             sess.refresh_mcp_servers_if_requested(&current_context)
                 .await;
             let regular_task = sess.take_startup_regular_task().await.unwrap_or_default();
             sess.spawn_task(Arc::clone(&current_context), items, regular_task)
                 .await;
-            sess.set_previous_context_item(Some(current_context.to_turn_context_item()))
-                .await;
         }
     }
 
@@ -4282,6 +4269,19 @@ pub(crate) async fn run_turn(
         error!("Failed to run pre-sampling compact");
         return None;
     }
+    let previous_model = sess.previous_model().await;
+    let previous_context_item = sess.previous_context_item().await;
+    let update_items = sess.build_settings_update_items(
+        previous_context_item.as_ref(),
+        previous_model.as_deref(),
+        turn_context.as_ref(),
+    );
+    if !update_items.is_empty() {
+        sess.record_conversation_items(turn_context.as_ref(), &update_items)
+            .await;
+    }
+    sess.set_previous_context_item(Some(turn_context.to_turn_context_item()))
+        .await;
 
     let skills_outcome = Some(
         sess.services

codex-rs/core/tests/suite/compact.rs

@@ -3007,7 +3007,7 @@ async fn snapshot_request_shape_pre_turn_compaction_including_incoming_user_mess
     insta::assert_snapshot!(
         "pre_turn_compaction_including_incoming_shapes",
         format_labeled_requests_snapshot(
-            "Pre-turn auto-compaction with a context override emits the context diff in the compact request while the incoming user message is still excluded.",
+            "Pre-turn auto-compaction with a context override excludes incoming-turn context diffs from the compact request, then appends those diffs immediately before the incoming user message after compaction.",
             &[
                 ("Local Compaction Request", &requests[2]),
                 ("Local Post-Compaction History Layout", &requests[3]),
@@ -3021,11 +3021,21 @@ async fn snapshot_request_shape_pre_turn_compaction_including_incoming_user_mess
             .any(|text| text == "USER_THREE"),
         "current behavior excludes incoming user message from pre-turn compaction input"
     );
+    let compact_body = requests[2].body_json().to_string();
+    assert!(
+        !compact_body.contains(PRETURN_CONTEXT_DIFF_CWD),
+        "pre-turn compaction request should exclude incoming context diff items"
+    );
     let follow_up_user_texts = requests[3].message_input_texts("user");
     assert!(
         follow_up_user_texts.iter().any(|text| text == "USER_THREE"),
         "expected post-compaction follow-up request to keep incoming user text"
     );
+    let follow_up_body = requests[3].body_json().to_string();
+    assert!(
+        follow_up_body.contains(PRETURN_CONTEXT_DIFF_CWD),
+        "post-compaction follow-up request should include the incoming context diff items"
+    );
     let follow_up_user_images = requests[3].message_input_image_urls("user");
     assert!(
         follow_up_user_images

codex-rs/core/tests/suite/compact_remote.rs

@@ -1390,13 +1390,27 @@ async fn snapshot_request_shape_remote_pre_turn_compaction_including_incoming_us
     insta::assert_snapshot!(
         "remote_pre_turn_compaction_including_incoming_shapes",
         format_labeled_requests_snapshot(
-            "Remote pre-turn auto-compaction with a context override emits the context diff in the compact request while excluding the incoming user message.",
+            "Remote pre-turn auto-compaction with a context override excludes incoming-turn context diffs from the compact request, then appends those diffs immediately before the incoming user message after compaction.",
             &[
                 ("Remote Compaction Request", &compact_request),
                 ("Remote Post-Compaction History Layout", &requests[2]),
             ]
         )
     );
+    assert!(
+        !compact_request
+            .body_json()
+            .to_string()
+            .contains(PRETURN_CONTEXT_DIFF_CWD),
+        "pre-turn remote compaction request should exclude incoming context diff items"
+    );
+    assert!(
+        requests[2]
+            .body_json()
+            .to_string()
+            .contains(PRETURN_CONTEXT_DIFF_CWD),
+        "post-compaction remote request should include incoming context diff items"
+    );
     assert_eq!(
         requests[2]
             .message_input_texts("user")

codex-rs/core/tests/suite/snapshots/all__suite__compact__pre_turn_compaction_including_incoming_shapes.snap

@@ -1,8 +1,8 @@
 ---
 source: core/tests/suite/compact.rs
-expression: "format_labeled_requests_snapshot(\"Pre-turn auto-compaction with a context override emits the context diff in the compact request while the incoming user message is still excluded.\",\n&[(\"Local Compaction Request\", &requests[2]),\n(\"Local Post-Compaction History Layout\", &requests[3]),])"
+expression: "format_labeled_requests_snapshot(\"Pre-turn auto-compaction with a context override excludes incoming-turn context diffs from the compact request, then appends those diffs immediately before the incoming user message after compaction.\",\n&[(\"Local Compaction Request\", &requests[2]),\n(\"Local Post-Compaction History Layout\", &requests[3]),])"
 ---
-Scenario: Pre-turn auto-compaction with a context override emits the context diff in the compact request while the incoming user message is still excluded.
+Scenario: Pre-turn auto-compaction with a context override excludes incoming-turn context diffs from the compact request, then appends those diffs immediately before the incoming user message after compaction.
 
 ## Local Compaction Request
 00:message/developer:<PERMISSIONS_INSTRUCTIONS>
@@ -12,8 +12,7 @@ Scenario: Pre-turn auto-compaction with a context override emits the context dif
 04:message/assistant:FIRST_REPLY
 05:message/user:USER_TWO
 06:message/assistant:SECOND_REPLY
-07:message/user:<ENVIRONMENT_CONTEXT:cwd=PRETURN_CONTEXT_DIFF_CWD>
-08:message/user:<SUMMARIZATION_PROMPT>
+07:message/user:<SUMMARIZATION_PROMPT>
 
 ## Local Post-Compaction History Layout
 00:message/developer:<PERMISSIONS_INSTRUCTIONS>
@@ -22,4 +21,5 @@ Scenario: Pre-turn auto-compaction with a context override emits the context dif
 03:message/user:USER_ONE
 04:message/user:USER_TWO
 05:message/user:<COMPACTION_SUMMARY>\nPRE_TURN_SUMMARY
-06:message/user:<image> | <input_image:image_url> | </image> | USER_THREE
+06:message/user:<ENVIRONMENT_CONTEXT:cwd=PRETURN_CONTEXT_DIFF_CWD>
+07:message/user:<image> | <input_image:image_url> | </image> | USER_THREE

codex-rs/core/tests/suite/snapshots/all__suite__compact_remote__remote_pre_turn_compaction_including_incoming_shapes.snap

@@ -1,8 +1,8 @@
 ---
 source: core/tests/suite/compact_remote.rs
-expression: "format_labeled_requests_snapshot(\"Remote pre-turn auto-compaction with a context override emits the context diff in the compact request while excluding the incoming user message.\",\n&[(\"Remote Compaction Request\", &compact_request),\n(\"Remote Post-Compaction History Layout\", &requests[2]),])"
+expression: "format_labeled_requests_snapshot(\"Remote pre-turn auto-compaction with a context override excludes incoming-turn context diffs from the compact request, then appends those diffs immediately before the incoming user message after compaction.\",\n&[(\"Remote Compaction Request\", &compact_request),\n(\"Remote Post-Compaction History Layout\", &requests[2]),])"
 ---
-Scenario: Remote pre-turn auto-compaction with a context override emits the context diff in the compact request while excluding the incoming user message.
+Scenario: Remote pre-turn auto-compaction with a context override excludes incoming-turn context diffs from the compact request, then appends those diffs immediately before the incoming user message after compaction.
 
 ## Remote Compaction Request
 00:message/developer:<PERMISSIONS_INSTRUCTIONS>
@@ -12,7 +12,6 @@ Scenario: Remote pre-turn auto-compaction with a context override emits the cont
 04:message/assistant:REMOTE_FIRST_REPLY
 05:message/user:USER_TWO
 06:message/assistant:REMOTE_SECOND_REPLY
-07:message/user:<ENVIRONMENT_CONTEXT:cwd=PRETURN_CONTEXT_DIFF_CWD>
 
 ## Remote Post-Compaction History Layout
 00:message/user:USER_ONE
@@ -21,4 +20,5 @@ Scenario: Remote pre-turn auto-compaction with a context override emits the cont
 03:message/user:<AGENTS_MD>
 04:message/user:<ENVIRONMENT_CONTEXT:cwd=PRETURN_CONTEXT_DIFF_CWD>
 05:message/user:<COMPACTION_SUMMARY>\nREMOTE_PRE_TURN_SUMMARY
-06:message/user:USER_THREE
+06:message/user:<ENVIRONMENT_CONTEXT:cwd=PRETURN_CONTEXT_DIFF_CWD>
+07:message/user:USER_THREE