core: render remote environment cwd natively (#28152)

## Why

Model-visible `<environment_context>` should match the environment of
the executor, not of the app server.

Stacked on #28146.

## What

- Keep selected environment cwd values as `PathUri` while building
environment context.
- Render cwd text using the path convention represented by the URI, with
the canonical URI as a fallback.
- Preserve compatibility with legacy `TurnContextItem.cwd` values when
reconstructing and diffing context.
- Extend the Wine-backed remote Windows test to assert that the model
sees `powershell` and `C:\windows`.

codex-rs/rollout/src/metadata.rs

@@ -111,7 +111,7 @@ pub async fn extract_metadata_from_rollout(
     })?;
     let mut metadata = builder.build(default_provider);
     for item in &items {
-        apply_rollout_item(&mut metadata, item, default_provider);
+        apply_rollout_item(&mut metadata, item, default_provider)?;
     }
     if let Some(updated_at) = file_modified_time_utc(rollout_path).await {
         metadata.updated_at = updated_at;

codex-rs/rollout/src/metadata_tests.rs

@@ -69,7 +69,8 @@ async fn extract_metadata_from_rollout_uses_session_meta() {
 
     let builder = builder_from_session_meta(&session_meta_line, path.as_path()).expect("builder");
     let mut expected = builder.build("openai");
-    apply_rollout_item(&mut expected, &rollout_line.item, "openai");
+    apply_rollout_item(&mut expected, &rollout_line.item, "openai")
+        .expect("rollout item should apply");
     expected.updated_at = file_modified_time_utc(&path).await.expect("mtime");
 
     assert_eq!(outcome.metadata, expected);

codex-rs/rollout/src/recorder.rs

@@ -1765,15 +1765,16 @@ async fn resume_candidate_matches_cwd(
 
     if let Ok((items, _, _)) = RolloutRecorder::load_rollout_items(rollout_path).await
         && let Some(latest_turn_context_cwd) = items.iter().rev().find_map(|item| match item {
-            RolloutItem::TurnContext(turn_context) => Some(turn_context.cwd.as_path()),
+            RolloutItem::TurnContext(turn_context) => Some(&turn_context.cwd),
             RolloutItem::SessionMeta(_)
             | RolloutItem::ResponseItem(_)
             | RolloutItem::InterAgentCommunication(_)
             | RolloutItem::Compacted(_)
             | RolloutItem::EventMsg(_) => None,
         })
+        && let Ok(latest_turn_context_cwd) = latest_turn_context_cwd.to_abs_path()
     {
-        return cwd_matches(latest_turn_context_cwd, cwd);
+        return cwd_matches(latest_turn_context_cwd.as_path(), cwd);
     }
 
     metadata::extract_metadata_from_rollout(rollout_path, default_provider)

codex-rs/rollout/src/recorder_tests.rs

@@ -1134,7 +1134,8 @@ async fn resume_candidate_matches_cwd_reads_latest_turn_context() -> std::io::Re
         timestamp: "2025-01-03T13:00:01Z".to_string(),
         item: RolloutItem::TurnContext(TurnContextItem {
             turn_id: Some("turn-1".to_string()),
-            cwd: latest_cwd.clone(),
+            cwd: serde_json::from_value(serde_json::json!(&latest_cwd))
+                .expect("absolute latest cwd"),
             workspace_roots: None,
             current_date: None,
             timezone: None,