Retain assistant context for Guardian authorization reviews (#47582)

## Why

Ordinary user replies can depend on preceding assistant messages. Losing those messages during compaction can leave Guardian without the context needed to interpret a reply's scope.

## What changed

- Retain original assistant messages, including commentary, with their recorded order across checkpoints and resume. Exclude compaction output from this evidence.
- Include assistant context in local and delegated reviews as untrusted context, with separate storage limits and lower budget priority than user instructions.
- Prefer assistant context preceding ordinary replies when selecting bounded root evidence, and report unavailable context without inferring what a reply refers to.
- Preserve inherited context scope and remove assistant evidence beyond rollback boundaries, including during rollout migration.

## Testing

Extend coverage for compaction and resume, checkpoint migration, queued-input ordering and rollback, role labeling, and evidence budgets that preserve user restrictions while dropping assistant context.

GitOrigin-RevId: 886189b0be29ffc3d324b56f5d0b673d6b8d84da

codex-rs/thread-store/src/local/rollout_migration/rollback_plan.rs

@@ -158,6 +158,19 @@ impl RollbackPlanner {
         match &line.item {
             RolloutItem::SessionMeta(_) => self.record_boundaries[index] = None,
             RolloutItem::ResponseItem(response) => {
+                if matches!(&response.item, ResponseItem::Message { role, .. } if role == "assistant")
+                    || matches!(&response.item, ResponseItem::FunctionCall { .. })
+                {
+                    self.retained_fact_sources.push(RetainedFactSource {
+                        record_index: index,
+                        turn_id: response.turn_id().unwrap_or_default().to_owned(),
+                        acceptance_order: response
+                            .metadata
+                            .as_ref()
+                            .filter(|metadata| !metadata.inherited_user_message)
+                            .and_then(|metadata| metadata.user_input_order),
+                    });
+                }
                 if let Some(boundary) = paired_delivery_boundary {
                     self.record_boundaries[index] = Some(boundary);
                     self.boundaries[boundary].message_id = response.id().cloned();

codex-rs/thread-store/src/local/rollout_migration_tests.rs

@@ -1399,7 +1399,8 @@ async fn assert_migrated_evidence_order(steer_order: Option<u64>) {
             {"order": if steer_order.is_some() { 2 } else { 1 }, "turn_id": "shared-turn", "call_id": "before", "questions": [{"question": "Publish?", "answer": "Only privately."}]},
             {"order": 3, "turn_id": "shared-turn", "call_id": "after", "questions": [{"question": "Publish the README?", "answer": "Do not publish it."}]}
         ],
-        "incomplete": false, "user_messages_incomplete": false, "next_order": 4
+        "incomplete": false, "user_messages_incomplete": false, "next_order": 4,
+        "assistant_messages": [], "assistant_messages_incomplete": true
     });
     checkpoint.retained_context =
         Some(serde_json::from_value(retained.clone()).expect("retained fixture"));
@@ -1456,6 +1457,18 @@ async fn assert_migrated_evidence_order(steer_order: Option<u64>) {
             rollout_response_item(initial.clone()),
             user_message(INITIAL),
             RolloutItem::RetainedContext(answers[0].clone()),
+            RolloutItem::ResponseItem(codex_rollout::ResponseItemEnvelope {
+                item: serde_json::from_value(json!({
+                    "type": "message", "id": "late-assistant", "role": "assistant",
+                    "content": [{"type": "output_text", "text": "Late assistant question?"}],
+                    "internal_chat_message_metadata_passthrough": {"turn_id": "shared-turn"}
+                }))
+                .expect("assistant message"),
+                metadata: Some(
+                    serde_json::from_value(json!({"user_input_order": 2}))
+                        .expect("assistant order"),
+                ),
+            }),
             RolloutItem::Compacted(before_steer),
             RolloutItem::ResponseItem(codex_rollout::ResponseItemEnvelope {
                 item: steer,
@@ -1487,6 +1500,13 @@ async fn assert_migrated_evidence_order(steer_order: Option<u64>) {
         .await
         .expect("migrate same-turn rollback");
     let migrated = read_rollout(&path);
+    assert_eq!(
+        migrated.iter().any(|line| matches!(&line.item,
+            RolloutItem::ResponseItem(envelope)
+                if envelope.item.id().is_some_and(|id| id.as_str() == "late-assistant")
+        )),
+        steer_order.is_none()
+    );
     let checkpoints = migrated
         .iter()
         .filter_map(|line| match &line.item {