fix(rollout): favor newest session mtime

code-rs/Cargo.toml

@@ -114,6 +114,7 @@ env-flags = "0.1.1"
 env_logger = "0.11.5"
 escargot = "0.5"
 eventsource-stream = "0.2.3"
+filetime = "0.2"
 futures = "0.3"
 icu_decimal = "2.0.0"
 icu_locale_core = "2.0.0"

code-rs/core/Cargo.toml

@@ -102,7 +102,9 @@ windows-sys = { version = "0.61.2", features = [
 ] }
 
 [dev-dependencies]
+filetime = { workspace = true }
 maplit = { workspace = true }
+once_cell = { workspace = true }
 pretty_assertions = { workspace = true }
 tokio-test = { workspace = true }
 wiremock = { workspace = true }

code-rs/core/src/rollout/list.rs

@@ -11,6 +11,7 @@ use time::OffsetDateTime;
 use time::PrimitiveDateTime;
 use time::format_description::FormatItem;
 use time::macros::format_description;
+use time::format_description::well_known::Rfc3339;
 use uuid::Uuid;
 
 use super::SESSIONS_SUBDIR;
@@ -47,6 +48,8 @@ pub struct ConversationItem {
     pub created_at: Option<String>,
     /// RFC3339 timestamp string for the most recent response in the tail, if available.
     pub updated_at: Option<String>,
+    /// RFC3339 timestamp string for the file's last modification time, if available.
+    pub modified_at: Option<String>,
 }
 
 #[derive(Default)]
@@ -147,7 +150,7 @@ async fn traverse_directories_for_paths(
     anchor: Option<Cursor>,
     allowed_sources: &[SessionSource],
 ) -> io::Result<ConversationsPage> {
-    let mut items: Vec<ConversationItem> = Vec::with_capacity(page_size);
+    let mut candidates: Vec<(OffsetDateTime, OffsetDateTime, Uuid, ConversationItem)> = Vec::new();
     let mut scanned_files = 0usize;
     let mut anchor_passed = anchor.is_none();
     let (anchor_ts, anchor_id) = match anchor {
@@ -171,7 +174,7 @@ async fn traverse_directories_for_paths(
                 if scanned_files >= MAX_SCAN_FILES {
                     break 'outer;
                 }
-                let mut day_files = collect_files(day_path, |name_str, path| {
+                let day_files = collect_files(day_path, |name_str, path| {
                     if !name_str.starts_with("rollout-") || !name_str.ends_with(".jsonl") {
                         return None;
                     }
@@ -180,11 +183,22 @@ async fn traverse_directories_for_paths(
                         .map(|(ts, id)| (ts, id, name_str.to_string(), path.to_path_buf()))
                 })
                 .await?;
-                // Stable ordering within the same second: (timestamp desc, uuid desc)
-                day_files.sort_by_key(|(ts, sid, _name_str, _path)| (Reverse(*ts), Reverse(*sid)));
+                let mut day_entries = Vec::with_capacity(day_files.len());
                 for (ts, sid, _name_str, path) in day_files.into_iter() {
+                    let modified = tokio::fs::metadata(&path)
+                        .await
+                        .ok()
+                        .and_then(|meta| meta.modified().ok())
+                        .map(OffsetDateTime::from)
+                        .unwrap_or(OffsetDateTime::UNIX_EPOCH);
+                    day_entries.push((modified, ts, sid, path));
+                }
+                day_entries.sort_by_key(|(modified, ts, sid, _)| {
+                    (Reverse(*modified), Reverse(*ts), Reverse(*sid))
+                });
+                for (modified, ts, sid, path) in day_entries.into_iter() {
                     scanned_files += 1;
-                    if scanned_files >= MAX_SCAN_FILES && items.len() >= page_size {
+                    if scanned_files >= MAX_SCAN_FILES {
                         break 'outer;
                     }
                     if !anchor_passed {
@@ -194,9 +208,6 @@ async fn traverse_directories_for_paths(
                             continue;
                         }
                     }
-                    if items.len() == page_size {
-                        break 'outer;
-                    }
                     let summary = read_head_and_tail(&path, HEAD_RECORD_LIMIT, TAIL_RECORD_LIMIT)
                         .await
                         .unwrap_or_default();
@@ -216,19 +227,39 @@ async fn traverse_directories_for_paths(
                             ..
                         } = summary;
                         updated_at = updated_at.or_else(|| created_at.clone());
-                        items.push(ConversationItem {
-                            path,
-                            head,
-                            tail,
-                            created_at,
-                            updated_at,
-                        });
+                        let modified_at = if modified == OffsetDateTime::UNIX_EPOCH {
+                            updated_at.clone().or_else(|| created_at.clone())
+                        } else {
+                            modified.format(&Rfc3339).ok()
+                        };
+                        candidates.push((
+                            modified,
+                            ts,
+                            sid,
+                            ConversationItem {
+                                path,
+                                head,
+                                tail,
+                                created_at,
+                                updated_at,
+                                modified_at,
+                            },
+                        ));
                     }
                 }
             }
         }
     }
 
+    candidates.sort_by_key(|(modified, ts, sid, _)| {
+        (Reverse(*modified), Reverse(*ts), Reverse(*sid))
+    });
+
+    let mut items: Vec<ConversationItem> = Vec::with_capacity(page_size.min(candidates.len()));
+    for (_, _, _, item) in candidates.into_iter().take(page_size) {
+        items.push(item);
+    }
+
     let next = build_next_cursor(&items);
     Ok(ConversationsPage {
         items,

code-rs/core/src/rollout/tests.rs

@@ -6,10 +6,12 @@ use std::io::BufWriter;
 use std::io::Write;
 use std::path::{Path, PathBuf};
 
+use filetime::{set_file_mtime, FileTime};
 use tempfile::TempDir;
 use time::OffsetDateTime;
 use time::PrimitiveDateTime;
 use time::format_description::FormatItem;
+use time::format_description::well_known::Rfc3339;
 use time::macros::format_description;
 use uuid::Uuid;
 
@@ -19,6 +21,7 @@ use crate::rollout::list::ConversationsPage;
 use crate::rollout::list::Cursor;
 use crate::rollout::list::get_conversation;
 use crate::rollout::list::get_conversations;
+use std::time::{Duration, SystemTime};
 use code_protocol::models::{ContentItem, ResponseItem};
 use code_protocol::ConversationId;
 use code_protocol::protocol::{
@@ -426,7 +429,7 @@ async fn test_pagination_cursor() {
     ];
     let expected_cursor1: Cursor =
         serde_json::from_str(&format!("\"2025-03-04T09-00-00|{u4}\"")).unwrap();
-    assert_page_summary(&page1, &expected_page1_items, Some(expected_cursor1.clone()), 3);
+    assert_page_summary(&page1, &expected_page1_items, Some(expected_cursor1.clone()), 5);
 
     let page2 = get_conversations(
         home,
@@ -524,6 +527,69 @@ async fn test_get_conversation_contents() {
     }
 }
 
+#[tokio::test]
+async fn test_list_conversations_prefers_recent_mtime() {
+    let temp = TempDir::new().unwrap();
+    let home = temp.path();
+
+    let older_uuid = Uuid::from_u128(0x11);
+    let newer_uuid = Uuid::from_u128(0x22);
+
+    write_session_file(
+        home,
+        "2025-08-01T10-00-00",
+        older_uuid,
+        1,
+        Some(SessionSource::VSCode),
+    )
+    .unwrap();
+    write_session_file(
+        home,
+        "2025-09-01T10-00-00",
+        newer_uuid,
+        1,
+        Some(SessionSource::VSCode),
+    )
+    .unwrap();
+
+    let older_path = home
+        .join("sessions")
+        .join("2025")
+        .join("08")
+        .join("01")
+        .join(format!("rollout-2025-08-01T10-00-00-{older_uuid}.jsonl"));
+
+    let future_time = SystemTime::now() + Duration::from_secs(300);
+    set_file_mtime(&older_path, FileTime::from_system_time(future_time)).unwrap();
+
+    let page = get_conversations(home, 1, None, INTERACTIVE_SESSION_SOURCES)
+        .await
+        .unwrap();
+
+    let first = page.items.first().expect("expected at least one session");
+    assert_eq!(first.path, older_path);
+
+    let modified_at = first
+        .modified_at
+        .as_deref()
+        .expect("expected modified_at");
+    let updated_at = first
+        .updated_at
+        .as_deref()
+        .expect("expected updated_at");
+
+    let modified_dt = OffsetDateTime::parse(modified_at, &Rfc3339).expect("parse modified_at");
+    let format: &[FormatItem] =
+        format_description!("[year]-[month]-[day]T[hour]-[minute]-[second]");
+    let updated_dt = PrimitiveDateTime::parse(updated_at, format)
+        .expect("parse updated_at")
+        .assume_utc();
+    assert!(
+        modified_dt > updated_dt,
+        "modified_at should reflect newer filesystem mtime"
+    );
+}
+
 #[tokio::test]
 async fn test_stable_ordering_same_second_pagination() {
     let temp = TempDir::new().unwrap();