fix(guardian): fix ordering of guardian events (#16462)

Guardian events were emitted a bit out of order for CommandExecution
items. This would make it hard for the frontend to render a guardian
auto-review, which has this payload:
```
pub struct ItemGuardianApprovalReviewStartedNotification {
    pub thread_id: String,
    pub turn_id: String,
    pub target_item_id: String,
    pub review: GuardianApprovalReview,
    // FYI this is no longer a json blob
    pub action: Option<JsonValue>,
}
```

There is a `target_item_id` the auto-approval review is referring to,
but the actual item had not been emitted yet.

Before this PR:
- `item/autoApprovalReview/started`
- `item/autoApprovalReview/completed`, and if approved...
- `item/started`
- `item/completed`

After this PR:
- `item/started`
- `item/autoApprovalReview/started`
- `item/autoApprovalReview/completed`
- `item/completed`

This lines up much better with existing patterns (i.e. human review in
`Default mode`, where app-server would send a server request to prompt
for user approval after `item/started`), and makes it easier for clients
to render what guardian is actually reviewing.

We do this following a similar pattern as `FileChange` (aka apply patch)
items, where we create a FileChange item and emit `item/started` if we
see the apply patch approval request, before the actual apply patch call
runs.

codex-rs/app-server-protocol/src/protocol/thread_history.rs

@@ -1,16 +1,18 @@
+use crate::protocol::item_builders::build_command_execution_begin_item;
+use crate::protocol::item_builders::build_command_execution_end_item;
+use crate::protocol::item_builders::build_file_change_approval_request_item;
+use crate::protocol::item_builders::build_file_change_begin_item;
+use crate::protocol::item_builders::build_file_change_end_item;
+use crate::protocol::item_builders::build_item_from_guardian_event;
 use crate::protocol::v2::CollabAgentState;
 use crate::protocol::v2::CollabAgentTool;
 use crate::protocol::v2::CollabAgentToolCallStatus;
-use crate::protocol::v2::CommandAction;
 use crate::protocol::v2::CommandExecutionStatus;
 use crate::protocol::v2::DynamicToolCallOutputContentItem;
 use crate::protocol::v2::DynamicToolCallStatus;
-use crate::protocol::v2::FileUpdateChange;
 use crate::protocol::v2::McpToolCallError;
 use crate::protocol::v2::McpToolCallResult;
 use crate::protocol::v2::McpToolCallStatus;
-use crate::protocol::v2::PatchApplyStatus;
-use crate::protocol::v2::PatchChangeKind;
 use crate::protocol::v2::ThreadItem;
 use crate::protocol::v2::Turn;
 use crate::protocol::v2::TurnError as V2TurnError;
@@ -31,6 +33,8 @@ use codex_protocol::protocol::ErrorEvent;
 use codex_protocol::protocol::EventMsg;
 use codex_protocol::protocol::ExecCommandBeginEvent;
 use codex_protocol::protocol::ExecCommandEndEvent;
+use codex_protocol::protocol::GuardianAssessmentEvent;
+use codex_protocol::protocol::GuardianAssessmentStatus;
 use codex_protocol::protocol::ImageGenerationBeginEvent;
 use codex_protocol::protocol::ImageGenerationEndEvent;
 use codex_protocol::protocol::ItemCompletedEvent;
@@ -53,6 +57,14 @@ use std::collections::HashMap;
 use tracing::warn;
 use uuid::Uuid;
 
+#[cfg(test)]
+use crate::protocol::v2::CommandAction;
+#[cfg(test)]
+use crate::protocol::v2::FileUpdateChange;
+#[cfg(test)]
+use crate::protocol::v2::PatchApplyStatus;
+#[cfg(test)]
+use crate::protocol::v2::PatchChangeKind;
 #[cfg(test)]
 use codex_protocol::protocol::ExecCommandStatus as CoreExecCommandStatus;
 #[cfg(test)]
@@ -149,6 +161,7 @@ impl ThreadHistoryBuilder {
             EventMsg::WebSearchEnd(payload) => self.handle_web_search_end(payload),
             EventMsg::ExecCommandBegin(payload) => self.handle_exec_command_begin(payload),
             EventMsg::ExecCommandEnd(payload) => self.handle_exec_command_end(payload),
+            EventMsg::GuardianAssessment(payload) => self.handle_guardian_assessment(payload),
             EventMsg::ApplyPatchApprovalRequest(payload) => {
                 self.handle_apply_patch_approval_request(payload)
             }
@@ -375,57 +388,12 @@ impl ThreadHistoryBuilder {
     }
 
     fn handle_exec_command_begin(&mut self, payload: &ExecCommandBeginEvent) {
-        let command = shlex::try_join(payload.command.iter().map(String::as_str))
-            .unwrap_or_else(|_| payload.command.join(" "));
-        let command_actions = payload
-            .parsed_cmd
-            .iter()
-            .cloned()
-            .map(CommandAction::from)
-            .collect();
-        let item = ThreadItem::CommandExecution {
-            id: payload.call_id.clone(),
-            command,
-            cwd: payload.cwd.clone(),
-            process_id: payload.process_id.clone(),
-            source: payload.source.into(),
-            status: CommandExecutionStatus::InProgress,
-            command_actions,
-            aggregated_output: None,
-            exit_code: None,
-            duration_ms: None,
-        };
+        let item = build_command_execution_begin_item(payload);
         self.upsert_item_in_turn_id(&payload.turn_id, item);
     }
 
     fn handle_exec_command_end(&mut self, payload: &ExecCommandEndEvent) {
-        let status: CommandExecutionStatus = (&payload.status).into();
-        let duration_ms = i64::try_from(payload.duration.as_millis()).unwrap_or(i64::MAX);
-        let aggregated_output = if payload.aggregated_output.is_empty() {
-            None
-        } else {
-            Some(payload.aggregated_output.clone())
-        };
-        let command = shlex::try_join(payload.command.iter().map(String::as_str))
-            .unwrap_or_else(|_| payload.command.join(" "));
-        let command_actions = payload
-            .parsed_cmd
-            .iter()
-            .cloned()
-            .map(CommandAction::from)
-            .collect();
-        let item = ThreadItem::CommandExecution {
-            id: payload.call_id.clone(),
-            command,
-            cwd: payload.cwd.clone(),
-            process_id: payload.process_id.clone(),
-            source: payload.source.into(),
-            status,
-            command_actions,
-            aggregated_output,
-            exit_code: Some(payload.exit_code),
-            duration_ms: Some(duration_ms),
-        };
+        let item = build_command_execution_end_item(payload);
         // Command completions can arrive out of order. Unified exec may return
         // while a PTY is still running, then emit ExecCommandEnd later from a
         // background exit watcher when that process finally exits. By then, a
@@ -434,12 +402,26 @@ impl ThreadHistoryBuilder {
         self.upsert_item_in_turn_id(&payload.turn_id, item);
     }
 
-    fn handle_apply_patch_approval_request(&mut self, payload: &ApplyPatchApprovalRequestEvent) {
-        let item = ThreadItem::FileChange {
-            id: payload.call_id.clone(),
-            changes: convert_patch_changes(&payload.changes),
-            status: PatchApplyStatus::InProgress,
+    fn handle_guardian_assessment(&mut self, payload: &GuardianAssessmentEvent) {
+        let status = match payload.status {
+            GuardianAssessmentStatus::InProgress => CommandExecutionStatus::InProgress,
+            GuardianAssessmentStatus::Denied | GuardianAssessmentStatus::Aborted => {
+                CommandExecutionStatus::Declined
+            }
+            GuardianAssessmentStatus::Approved => return,
         };
+        let Some(item) = build_item_from_guardian_event(payload, status) else {
+            return;
+        };
+        if payload.turn_id.is_empty() {
+            self.upsert_item_in_current_turn(item);
+        } else {
+            self.upsert_item_in_turn_id(&payload.turn_id, item);
+        }
+    }
+
+    fn handle_apply_patch_approval_request(&mut self, payload: &ApplyPatchApprovalRequestEvent) {
+        let item = build_file_change_approval_request_item(payload);
         if payload.turn_id.is_empty() {
             self.upsert_item_in_current_turn(item);
         } else {
@@ -448,11 +430,7 @@ impl ThreadHistoryBuilder {
     }
 
     fn handle_patch_apply_begin(&mut self, payload: &PatchApplyBeginEvent) {
-        let item = ThreadItem::FileChange {
-            id: payload.call_id.clone(),
-            changes: convert_patch_changes(&payload.changes),
-            status: PatchApplyStatus::InProgress,
-        };
+        let item = build_file_change_begin_item(payload);
         if payload.turn_id.is_empty() {
             self.upsert_item_in_current_turn(item);
         } else {
@@ -461,12 +439,7 @@ impl ThreadHistoryBuilder {
     }
 
     fn handle_patch_apply_end(&mut self, payload: &PatchApplyEndEvent) {
-        let status: PatchApplyStatus = (&payload.status).into();
-        let item = ThreadItem::FileChange {
-            id: payload.call_id.clone(),
-            changes: convert_patch_changes(&payload.changes),
-            status,
-        };
+        let item = build_file_change_end_item(payload);
         if payload.turn_id.is_empty() {
             self.upsert_item_in_current_turn(item);
         } else {
@@ -1076,21 +1049,6 @@ fn render_review_output_text(output: &ReviewOutputEvent) -> String {
     }
 }
 
-pub fn convert_patch_changes(
-    changes: &HashMap<std::path::PathBuf, codex_protocol::protocol::FileChange>,
-) -> Vec<FileUpdateChange> {
-    let mut converted: Vec<FileUpdateChange> = changes
-        .iter()
-        .map(|(path, change)| FileUpdateChange {
-            path: path.to_string_lossy().into_owned(),
-            kind: map_patch_change_kind(change),
-            diff: format_file_change_diff(change),
-        })
-        .collect();
-    converted.sort_by(|a, b| a.path.cmp(&b.path));
-    converted
-}
-
 fn convert_dynamic_tool_content_items(
     items: &[codex_protocol::dynamic_tools::DynamicToolCallOutputContentItem],
 ) -> Vec<DynamicToolCallOutputContentItem> {
@@ -1108,33 +1066,6 @@ fn convert_dynamic_tool_content_items(
         .collect()
 }
 
-fn map_patch_change_kind(change: &codex_protocol::protocol::FileChange) -> PatchChangeKind {
-    match change {
-        codex_protocol::protocol::FileChange::Add { .. } => PatchChangeKind::Add,
-        codex_protocol::protocol::FileChange::Delete { .. } => PatchChangeKind::Delete,
-        codex_protocol::protocol::FileChange::Update { move_path, .. } => PatchChangeKind::Update {
-            move_path: move_path.clone(),
-        },
-    }
-}
-
-fn format_file_change_diff(change: &codex_protocol::protocol::FileChange) -> String {
-    match change {
-        codex_protocol::protocol::FileChange::Add { content } => content.clone(),
-        codex_protocol::protocol::FileChange::Delete { content } => content.clone(),
-        codex_protocol::protocol::FileChange::Update {
-            unified_diff,
-            move_path,
-        } => {
-            if let Some(path) = move_path {
-                format!("{unified_diff}\n\nMoved to: {}", path.display())
-            } else {
-                unified_diff.clone()
-            }
-        }
-    }
-}
-
 fn upsert_turn_item(items: &mut Vec<ThreadItem>, item: ThreadItem) {
     if let Some(existing_item) = items
         .iter_mut()
@@ -2030,6 +1961,136 @@ mod tests {
         );
     }
 
+    #[test]
+    fn reconstructs_declined_guardian_command_item() {
+        let events = vec![
+            EventMsg::TurnStarted(TurnStartedEvent {
+                turn_id: "turn-1".into(),
+                model_context_window: None,
+                collaboration_mode_kind: Default::default(),
+            }),
+            EventMsg::UserMessage(UserMessageEvent {
+                message: "review this command".into(),
+                images: None,
+                text_elements: Vec::new(),
+                local_images: Vec::new(),
+            }),
+            EventMsg::GuardianAssessment(GuardianAssessmentEvent {
+                id: "guardian-exec".into(),
+                turn_id: "turn-1".into(),
+                status: GuardianAssessmentStatus::InProgress,
+                risk_score: None,
+                risk_level: None,
+                rationale: None,
+                action: serde_json::from_value(serde_json::json!({
+                    "type": "command",
+                    "source": "shell",
+                    "command": "rm -rf /tmp/guardian",
+                    "cwd": "/tmp",
+                }))
+                .expect("guardian action"),
+            }),
+            EventMsg::GuardianAssessment(GuardianAssessmentEvent {
+                id: "guardian-exec".into(),
+                turn_id: "turn-1".into(),
+                status: GuardianAssessmentStatus::Denied,
+                risk_score: Some(97),
+                risk_level: Some(codex_protocol::protocol::GuardianRiskLevel::High),
+                rationale: Some("Would delete user data.".into()),
+                action: serde_json::from_value(serde_json::json!({
+                    "type": "command",
+                    "source": "shell",
+                    "command": "rm -rf /tmp/guardian",
+                    "cwd": "/tmp",
+                }))
+                .expect("guardian action"),
+            }),
+        ];
+
+        let items = events
+            .into_iter()
+            .map(RolloutItem::EventMsg)
+            .collect::<Vec<_>>();
+        let turns = build_turns_from_rollout_items(&items);
+        assert_eq!(turns.len(), 1);
+        assert_eq!(turns[0].items.len(), 2);
+        assert_eq!(
+            turns[0].items[1],
+            ThreadItem::CommandExecution {
+                id: "guardian-exec".into(),
+                command: "rm -rf /tmp/guardian".into(),
+                cwd: PathBuf::from("/tmp"),
+                process_id: None,
+                source: CommandExecutionSource::Agent,
+                status: CommandExecutionStatus::Declined,
+                command_actions: vec![CommandAction::Unknown {
+                    command: "rm -rf /tmp/guardian".into(),
+                }],
+                aggregated_output: None,
+                exit_code: None,
+                duration_ms: None,
+            }
+        );
+    }
+
+    #[test]
+    fn reconstructs_in_progress_guardian_execve_item() {
+        let events = vec![
+            EventMsg::TurnStarted(TurnStartedEvent {
+                turn_id: "turn-1".into(),
+                model_context_window: None,
+                collaboration_mode_kind: Default::default(),
+            }),
+            EventMsg::UserMessage(UserMessageEvent {
+                message: "run a subcommand".into(),
+                images: None,
+                text_elements: Vec::new(),
+                local_images: Vec::new(),
+            }),
+            EventMsg::GuardianAssessment(GuardianAssessmentEvent {
+                id: "guardian-execve".into(),
+                turn_id: "turn-1".into(),
+                status: GuardianAssessmentStatus::InProgress,
+                risk_score: None,
+                risk_level: None,
+                rationale: None,
+                action: serde_json::from_value(serde_json::json!({
+                    "type": "execve",
+                    "source": "shell",
+                    "program": "/bin/rm",
+                    "argv": ["/usr/bin/rm", "-f", "/tmp/file.sqlite"],
+                    "cwd": "/tmp",
+                }))
+                .expect("guardian action"),
+            }),
+        ];
+
+        let items = events
+            .into_iter()
+            .map(RolloutItem::EventMsg)
+            .collect::<Vec<_>>();
+        let turns = build_turns_from_rollout_items(&items);
+        assert_eq!(turns.len(), 1);
+        assert_eq!(turns[0].items.len(), 2);
+        assert_eq!(
+            turns[0].items[1],
+            ThreadItem::CommandExecution {
+                id: "guardian-execve".into(),
+                command: "/bin/rm -f /tmp/file.sqlite".into(),
+                cwd: PathBuf::from("/tmp"),
+                process_id: None,
+                source: CommandExecutionSource::Agent,
+                status: CommandExecutionStatus::InProgress,
+                command_actions: vec![CommandAction::Unknown {
+                    command: "/bin/rm -f /tmp/file.sqlite".into(),
+                }],
+                aggregated_output: None,
+                exit_code: None,
+                duration_ms: None,
+            }
+        );
+    }
+
     #[test]
     fn assigns_late_exec_completion_to_original_turn() {
         let events = vec![