diff --git a/codex-rs/core/src/rollout/format.rs b/codex-rs/core/src/rollout/format.rs
new file mode 100644
index 0000000000..2a73dd0824
--- /dev/null
+++ b/codex-rs/core/src/rollout/format.rs
@@ -0,0 +1,91 @@
+use codex_protocol::mcp_protocol::ConversationId;
+use time::OffsetDateTime;
+use time::PrimitiveDateTime;
+use time::format_description::FormatItem;
+use time::macros::format_description;
+use uuid::Uuid;
+
+/// Timestamp format used in rollout filenames: YYYY-MM-DDThh-mm-ss
+pub const FILENAME_TS_FMT: &[FormatItem] =
+    format_description!("[year]-[month]-[day]T[hour]-[minute]-[second]");
+
+/// Timestamp format used for JSONL records (UTC, second precision): YYYY-MM-DDThh:mm:ssZ
+pub const RECORD_TS_FMT: &[FormatItem] =
+    format_description!("[year]-[month]-[day]T[hour]:[minute]:[second]Z");
+
+/// Pagination cursor identifying a file by timestamp and UUID.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Cursor {
+    pub(crate) ts: OffsetDateTime,
+    pub(crate) id: Uuid,
+}
+
+impl Cursor {
+    pub fn new(ts: OffsetDateTime, id: Uuid) -> Self {
+        Self { ts, id }
+    }
+}
+
+impl serde::Serialize for Cursor {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        let ts_str = self
+            .ts
+            .format(FILENAME_TS_FMT)
+            .map_err(|e| serde::ser::Error::custom(format!("format error: {e}")))?;
+        serializer.serialize_str(&format!("{ts_str}|{}", self.id))
+    }
+}
+
+impl<'de> serde::Deserialize<'de> for Cursor {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let s = String::deserialize(deserializer)?;
+        parse_cursor(&s).ok_or_else(|| serde::de::Error::custom("invalid cursor"))
+    }
+}
+
+/// Parses a pagination cursor token in the form "<file_ts>|<uuid>".
+pub fn parse_cursor(token: &str) -> Option<Cursor> {
+    let (file_ts, uuid_str) = token.split_once('|')?;
+
+    let Ok(uuid) = Uuid::parse_str(uuid_str) else {
+        return None;
+    };
+
+    let ts = PrimitiveDateTime::parse(file_ts, FILENAME_TS_FMT)
+        .ok()?
+        .assume_utc();
+
+    Some(Cursor::new(ts, uuid))
+}
+
+/// Parse timestamp and UUID from a rollout filename.
+/// Expected format: rollout-YYYY-MM-DDThh-mm-ss-<uuid>.jsonl
+pub fn parse_timestamp_uuid_from_filename(name: &str) -> Option<(OffsetDateTime, Uuid)> {
+    let core = name.strip_prefix("rollout-")?.strip_suffix(".jsonl")?;
+
+    // Scan from the right for a '-' such that the suffix parses as a UUID.
+    let (sep_idx, uuid) = core
+        .match_indices('-')
+        .rev()
+        .find_map(|(i, _)| Uuid::parse_str(&core[i + 1..]).ok().map(|u| (i, u)))?;
+
+    let ts_str = &core[..sep_idx];
+    let ts = PrimitiveDateTime::parse(ts_str, FILENAME_TS_FMT)
+        .ok()?
+        .assume_utc();
+    Some((ts, uuid))
+}
+
+/// Build a rollout filename for a given timestamp and conversation id.
+pub fn build_rollout_filename(ts: OffsetDateTime, conversation_id: ConversationId) -> String {
+    let date_str = ts
+        .format(FILENAME_TS_FMT)
+        .unwrap_or_else(|e| panic!("failed to format timestamp: {e}"));
+    format!("rollout-{date_str}-{conversation_id}.jsonl")
+}