Record reasoning replay removal metrics (#61017)

## What changed

Parse reasoning removals from response `input_transformations` and carry the counts through completion events to sampling telemetry.

- Add `codex.responses.reasoning_replay` to distinguish unavailable reports, no reported removals, prefix mismatches, and other removals.
- Add `codex.responses.reasoning_items_removed` histograms by bounded removal reason, grouping unknown or missing reasons under `other`.
- Include zero counts for usable reports; exclude missing, null, or malformed reports from histograms without failing the response.
- Use the sampling step's session telemetry when recording response events.

## Testing

Add SSE and WebSocket integration coverage for report availability, removal counts, unknown reasons, zero observations, and `product_sku` tags in exported metrics.

GitOrigin-RevId: 83c70ca6067fa4b34bf5c463958b4632a7a0a188

codex-rs/core/src/client.rs

@@ -2842,6 +2842,7 @@ where
                     response_id,
                     token_usage,
                     usage_metadata,
+                    reasoning_removals,
                     end_turn,
                 }) => {
                     feedback_tags!(last_model_response_id = &response_id);
@@ -2866,6 +2867,7 @@ where
                             response_id,
                             token_usage,
                             usage_metadata,
+                            reasoning_removals,
                             end_turn,
                         }))
                         .await

codex-rs/core/src/client_tests.rs

@@ -1820,6 +1820,7 @@ async fn response_stream_records_last_model_feedback_ids() {
             response_id: "resp-123".to_string(),
             token_usage: None,
             usage_metadata: None,
+            reasoning_removals: None,
             end_turn: Some(true),
         }),
     ]);
@@ -2864,6 +2865,7 @@ async fn intercepted_output_reaches_trace_and_websocket_bookkeeping() -> anyhow:
             response_id: "response".into(),
             token_usage: None,
             usage_metadata: None,
+            reasoning_removals: None,
             end_turn: None,
         }))
         .await?;

codex-rs/core/src/compact_remote_v2.rs

@@ -1433,6 +1433,7 @@ mod tests {
             response_id: "resp-compact".into(),
             token_usage: Some(usage.clone()),
             usage_metadata: None,
+            reasoning_removals: None,
             end_turn: Some(true),
         })]);
         let result = collect_compaction_output(
@@ -1485,6 +1486,7 @@ mod tests {
                     amount: Some("0.125".to_string()),
                     metadata: Some(serde_json::json!({ "extra": { "label": "example" } })),
                 }),
+                reasoning_removals: None,
                 end_turn: Some(true),
             }),
         ]);

codex-rs/core/src/session/turn.rs

@@ -3178,7 +3178,7 @@ async fn try_run_sampling_request(
         let Some(event) = resampling.filter(event, &step_context.tool_router) else {
             continue;
         };
-        sess.services
+        step_context
             .session_telemetry
             .record_responses(&handle_responses, &event);
 
@@ -3532,6 +3532,7 @@ async fn try_run_sampling_request(
                 response_id,
                 token_usage,
                 usage_metadata,
+                reasoning_removals: _,
                 end_turn,
             } => {
                 if let Some(accepted) = pending_audio.take() {