Support file references in image edit requests (#47956)

## Why

Editing recent conversation images failed when the selected images included a file reference from a message or tool output.

## What changed

Use `ImageReference` in `ImageEditRequest` to accept both `image_url` and `file_id` inputs. Pass file references from conversation history through to image edit requests while preserving image selection order.

## Testing

Update tests to cover file references from messages and tool outputs, and serialization of mixed inline and file references in image edit requests.

GitOrigin-RevId: 2764bf36a81a62ddd25cf9df27346a434a10c449

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

@@ -122,13 +122,13 @@ mod tests {
     use crate::images::ImageBackground;
     use crate::images::ImageData;
     use crate::images::ImageQuality;
-    use crate::images::ImageUrl;
     use crate::provider::RetryConfig;
     use codex_client::Request;
     use codex_client::RequestBody;
     use codex_client::Response;
     use codex_client::StreamResponse;
     use codex_client::TransportError;
+    use codex_protocol::models::ImageReference;
     use http::StatusCode;
     use pretty_assertions::assert_eq;
     use serde_json::json;
@@ -339,9 +339,14 @@ mod tests {
         let (response, imagegen_request_id) = client
             .edit(
                 &ImageEditRequest {
-                    images: vec![ImageUrl {
-                        image_url: "data:image/png;base64,Zm9v".to_string(),
-                    }],
+                    images: vec![
+                        ImageReference::Inline {
+                            image_url: "data:image/png;base64,Zm9v".to_string(),
+                        },
+                        ImageReference::File {
+                            file_id: "file-image".to_string(),
+                        },
+                    ],
                     prompt: "add a red hat".to_string(),
                     background: None,
                     model: "gpt-image-1.5".to_string(),
@@ -362,7 +367,10 @@ mod tests {
         assert_eq!(
             request.body.as_ref().and_then(RequestBody::json),
             Some(&json!({
-                "images": [{"image_url": "data:image/png;base64,Zm9v"}],
+                "images": [
+                    {"image_url": "data:image/png;base64,Zm9v"},
+                    {"file_id": "file-image"},
+                ],
                 "prompt": "add a red hat",
                 "model": "gpt-image-1.5",
             }))

codex-rs/codex-api/src/images.rs

@@ -1,3 +1,4 @@
+use codex_protocol::models::ImageReference;
 use serde::Deserialize;
 use serde::Serialize;
 
@@ -17,7 +18,7 @@ pub struct ImageGenerationRequest {
 
 #[derive(Debug, Clone, Serialize, PartialEq)]
 pub struct ImageEditRequest {
-    pub images: Vec<ImageUrl>,
+    pub images: Vec<ImageReference>,
     pub prompt: String,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub background: Option<ImageBackground>,
@@ -30,11 +31,6 @@ pub struct ImageEditRequest {
     pub size: Option<String>,
 }
 
-#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
-pub struct ImageUrl {
-    pub image_url: String,
-}
-
 #[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
 #[serde(rename_all = "lowercase")]
 pub enum ImageBackground {

codex-rs/codex-api/src/lib.rs

@@ -83,7 +83,6 @@ pub use crate::images::ImageEditRequest;
 pub use crate::images::ImageGenerationRequest;
 pub use crate::images::ImageQuality;
 pub use crate::images::ImageResponse;
-pub use crate::images::ImageUrl;
 pub use crate::provider::Provider;
 pub use crate::provider::RetryConfig;
 pub use crate::provider::is_azure_responses_provider;