Add ordinals to paginated rollout records (#32332)

## Why

Paginated thread history needs durable ordering so consumers can process a rollout suffix without rebuilding all earlier history.

## What changed

- Add optional, zero-based ordinals to `RolloutLine` records in paginated rollouts while leaving legacy rollout serialization unchanged.
- Continue ordinals from the last valid record when appending or resuming, including after gaps or an incomplete tail, and reject overflow without appending.
- Add a stateless `project_rollout_line` helper that maps canonical turn lifecycle and completed-item records into thread-history change sets.

## Testing

- Cover ordinal assignment, legacy compatibility, resume and tail recovery, overflow handling, and thread-history projection for completed, failed, and interrupted turns.

GitOrigin-RevId: 3a9bb6cd2a1f674a9f154342e96e9aa3d8330781

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

@@ -371,6 +371,7 @@ async fn synthetic_call_output_id_is_stable_across_resumes() -> anyhow::Result<(
     let rollout = vec![
         RolloutLine {
             timestamp: "2024-01-01T00:00:00.000Z".to_string(),
+            ordinal: None,
             item: RolloutItem::SessionMeta(SessionMetaLine {
                 meta: SessionMeta {
                     session_id: thread_id.into(),
@@ -388,6 +389,7 @@ async fn synthetic_call_output_id_is_stable_across_resumes() -> anyhow::Result<(
         },
         RolloutLine {
             timestamp: "2024-01-01T00:00:01.000Z".to_string(),
+            ordinal: None,
             item: RolloutItem::ResponseItem(ResponseItem::FunctionCall {
                 id: Some(ResponseItemId::with_suffix("fc", "existing")),
                 name: "do_it".to_string(),
@@ -896,6 +898,7 @@ async fn resume_replays_legacy_js_repl_image_rollout_shapes() {
     let rollout = vec![
         RolloutLine {
             timestamp: "2024-01-01T00:00:00.000Z".to_string(),
+            ordinal: None,
             item: RolloutItem::SessionMeta(SessionMetaLine {
                 meta: SessionMeta {
                     session_id: thread_id.into(),
@@ -913,10 +916,12 @@ async fn resume_replays_legacy_js_repl_image_rollout_shapes() {
         },
         RolloutLine {
             timestamp: "2024-01-01T00:00:01.000Z".to_string(),
+            ordinal: None,
             item: RolloutItem::ResponseItem(legacy_custom_tool_call),
         },
         RolloutLine {
             timestamp: "2024-01-01T00:00:02.000Z".to_string(),
+            ordinal: None,
             item: RolloutItem::ResponseItem(ResponseItem::CustomToolCallOutput {
                 id: None,
                 call_id: "legacy-js-call".to_string(),
@@ -927,6 +932,7 @@ async fn resume_replays_legacy_js_repl_image_rollout_shapes() {
         },
         RolloutLine {
             timestamp: "2024-01-01T00:00:03.000Z".to_string(),
+            ordinal: None,
             item: RolloutItem::ResponseItem(ResponseItem::Message {
                 id: None,
                 role: "user".to_string(),
@@ -1032,6 +1038,7 @@ async fn resume_replays_image_tool_outputs_with_detail() {
     let rollout = vec![
         RolloutLine {
             timestamp: "2024-01-01T00:00:00.000Z".to_string(),
+            ordinal: None,
             item: RolloutItem::SessionMeta(SessionMetaLine {
                 meta: SessionMeta {
                     session_id: thread_id.into(),
@@ -1049,6 +1056,7 @@ async fn resume_replays_image_tool_outputs_with_detail() {
         },
         RolloutLine {
             timestamp: "2024-01-01T00:00:01.000Z".to_string(),
+            ordinal: None,
             item: RolloutItem::ResponseItem(ResponseItem::FunctionCall {
                 id: None,
                 name: "view_image".to_string(),
@@ -1060,6 +1068,7 @@ async fn resume_replays_image_tool_outputs_with_detail() {
         },
         RolloutLine {
             timestamp: "2024-01-01T00:00:01.500Z".to_string(),
+            ordinal: None,
             item: RolloutItem::ResponseItem(ResponseItem::FunctionCallOutput {
                 id: None,
                 call_id: function_call_id.to_string(),
@@ -1074,6 +1083,7 @@ async fn resume_replays_image_tool_outputs_with_detail() {
         },
         RolloutLine {
             timestamp: "2024-01-01T00:00:02.000Z".to_string(),
+            ordinal: None,
             item: RolloutItem::ResponseItem(ResponseItem::CustomToolCall {
                 id: None,
                 status: Some("completed".to_string()),
@@ -1086,6 +1096,7 @@ async fn resume_replays_image_tool_outputs_with_detail() {
         },
         RolloutLine {
             timestamp: "2024-01-01T00:00:02.500Z".to_string(),
+            ordinal: None,
             item: RolloutItem::ResponseItem(ResponseItem::CustomToolCallOutput {
                 id: None,
                 call_id: custom_call_id.to_string(),

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

@@ -384,10 +384,12 @@ async fn backfill_scans_existing_rollouts() -> Result<()> {
             let lines = [
                 RolloutLine {
                     timestamp: "2026-01-27T12:00:00Z".to_string(),
+                    ordinal: None,
                     item: RolloutItem::SessionMeta(session_meta_line),
                 },
                 RolloutLine {
                     timestamp: "2026-01-27T12:00:01Z".to_string(),
+                    ordinal: None,
                     item: RolloutItem::EventMsg(EventMsg::UserMessage(UserMessageEvent {
                         client_id: None,
                         message: "hello from backfill".to_string(),