Expose structured standalone web search results (#32898)

## Why

Standalone web search can return structured result DTOs separately from its
model-facing text output. App-server clients need access to that data without
coupling Codex to every result type or field.

## What changed

- Preserve the optional `results` array from `/v1/alpha/search` as opaque JSON
  through web-search completion events, thread history, and app-server
  `webSearch` items.
- Keep responses from older endpoints compatible when `results` is absent, and
  allow clients to ignore result types and fields they do not understand.
- Regenerate the protocol schemas and TypeScript definitions for the optional
  field.

## Testing

- Cover responses with missing, empty, and forward-compatible result payloads.
- Verify standalone web-search results round-trip through app-server item
  notifications and thread-item conversion.

GitOrigin-RevId: 739ef5694ece5733f7b8749ec41d6bfa3f33c8c5

codex-rs/codex-api/src/endpoint/search.rs

@@ -139,6 +139,12 @@ mod tests {
             serde_json::to_vec(&json!({
                 "encrypted_output": "ciphertext",
                 "output": "search result",
+                "results": [{
+                    "type": "text_result",
+                    "ref_id": "turn0search0",
+                    "url": "https://example.com/result",
+                    "future_field": {"preserved": true},
+                }],
             }))
             .expect("serialize response"),
         );
@@ -209,6 +215,12 @@ mod tests {
             SearchResponse {
                 encrypted_output: Some("ciphertext".to_string()),
                 output: "search result".to_string(),
+                results: Some(vec![json!({
+                    "type": "text_result",
+                    "ref_id": "turn0search0",
+                    "url": "https://example.com/result",
+                    "future_field": {"preserved": true},
+                })]),
             }
         );
 
@@ -267,4 +279,40 @@ mod tests {
             })
         );
     }
+    #[test]
+    fn search_response_defaults_missing_results_for_older_endpoints() {
+        let response: SearchResponse = serde_json::from_value(json!({
+            "encrypted_output": null,
+            "output": "search result",
+        }))
+        .expect("response without results should deserialize");
+
+        assert_eq!(
+            response,
+            SearchResponse {
+                encrypted_output: None,
+                output: "search result".to_string(),
+                results: None,
+            }
+        );
+    }
+
+    #[test]
+    fn search_response_preserves_supported_empty_results() {
+        let response: SearchResponse = serde_json::from_value(json!({
+            "encrypted_output": null,
+            "output": "search result",
+            "results": [],
+        }))
+        .expect("response with empty results should deserialize");
+
+        assert_eq!(
+            response,
+            SearchResponse {
+                encrypted_output: None,
+                output: "search result".to_string(),
+                results: Some(Vec::new()),
+            }
+        );
+    }
 }

codex-rs/codex-api/src/search.rs

@@ -3,6 +3,7 @@ use codex_protocol::models::ResponseItem;
 use schemars::JsonSchema;
 use serde::Deserialize;
 use serde::Serialize;
+use serde_json::Value as JsonValue;
 
 #[derive(Debug, Clone, Serialize, PartialEq)]
 pub struct SearchRequest {
@@ -297,4 +298,8 @@ pub enum AllowedCaller {
 pub struct SearchResponse {
     pub encrypted_output: Option<String>,
     pub output: String,
+    /// Structured result DTOs are passed to clients out-of-band from `output`.
+    /// Keep them opaque here so newer result variants remain forward-compatible.
+    #[serde(default)]
+    pub results: Option<Vec<JsonValue>>,
 }