Preserve image detail in app-server inputs (#20693)

## Summary

- Add optional image detail to user image inputs across core, app-server
v2, thread history/event mapping, and the generated app-server
schemas/types.
- Preserve requested detail when serializing Responses image inputs:
omitted detail stays on the existing `high` default, while explicit
`original` keeps local images on the original-resolution path.
- Support `high`/`original` consistently for tool image outputs,
including MCP `codex/imageDetail`, code-mode image helpers, and
`view_image`.

codex-rs/app-server-protocol/src/protocol/v2/tests.rs

@@ -15,6 +15,7 @@ use codex_protocol::memory_citation::MemoryCitation as CoreMemoryCitation;
 use codex_protocol::memory_citation::MemoryCitationEntry as CoreMemoryCitationEntry;
 use codex_protocol::models::AdditionalPermissionProfile as CoreAdditionalPermissionProfile;
 use codex_protocol::models::FileSystemPermissions as CoreFileSystemPermissions;
+use codex_protocol::models::ImageDetail;
 use codex_protocol::models::ManagedFileSystemPermissions as CoreManagedFileSystemPermissions;
 use codex_protocol::models::MessagePhase;
 use codex_protocol::models::NetworkPermissions as CoreNetworkPermissions;
@@ -2319,9 +2320,11 @@ fn core_turn_item_into_thread_item_converts_supported_variants() {
             },
             CoreUserInput::Image {
                 image_url: "https://example.com/image.png".to_string(),
+                detail: Some(ImageDetail::Original),
             },
             CoreUserInput::LocalImage {
                 path: PathBuf::from("local/image.png"),
+                detail: Some(ImageDetail::Original),
             },
             CoreUserInput::Skill {
                 name: "skill-creator".to_string(),
@@ -2345,9 +2348,11 @@ fn core_turn_item_into_thread_item_converts_supported_variants() {
                 },
                 UserInput::Image {
                     url: "https://example.com/image.png".to_string(),
+                    detail: Some(ImageDetail::Original),
                 },
                 UserInput::LocalImage {
                     path: PathBuf::from("local/image.png"),
+                    detail: Some(ImageDetail::Original),
                 },
                 UserInput::Skill {
                     name: "skill-creator".to_string(),
@@ -2562,6 +2567,33 @@ fn core_turn_item_into_thread_item_converts_supported_variants() {
     );
 }
 
+#[test]
+fn user_input_into_core_preserves_image_detail() {
+    assert_eq!(
+        UserInput::Image {
+            url: "https://example.com/image.png".to_string(),
+            detail: Some(ImageDetail::Original),
+        }
+        .into_core(),
+        CoreUserInput::Image {
+            image_url: "https://example.com/image.png".to_string(),
+            detail: Some(ImageDetail::Original),
+        }
+    );
+
+    assert_eq!(
+        UserInput::LocalImage {
+            path: PathBuf::from("local/image.png"),
+            detail: Some(ImageDetail::Original),
+        }
+        .into_core(),
+        CoreUserInput::LocalImage {
+            path: PathBuf::from("local/image.png"),
+            detail: Some(ImageDetail::Original),
+        }
+    );
+}
+
 #[test]
 fn skills_list_params_serialization_uses_force_reload() {
     assert_eq!(

codex-rs/app-server-protocol/src/protocol/v2/turn.rs

@@ -7,6 +7,7 @@ use codex_experimental_api_macros::ExperimentalApi;
 use codex_protocol::config_types::CollaborationMode;
 use codex_protocol::config_types::Personality;
 use codex_protocol::config_types::ReasoningSummary;
+use codex_protocol::models::ImageDetail;
 use codex_protocol::openai_models::ReasoningEffort;
 use codex_protocol::plan_tool::PlanItemArg as CorePlanItemArg;
 use codex_protocol::plan_tool::StepStatus as CorePlanStepStatus;
@@ -249,9 +250,15 @@ pub enum UserInput {
         text_elements: Vec<TextElement>,
     },
     Image {
+        #[serde(default)]
+        #[ts(optional)]
+        detail: Option<ImageDetail>,
         url: String,
     },
     LocalImage {
+        #[serde(default)]
+        #[ts(optional)]
+        detail: Option<ImageDetail>,
         path: PathBuf,
     },
     Skill {
@@ -274,8 +281,11 @@ impl UserInput {
                 text,
                 text_elements: text_elements.into_iter().map(Into::into).collect(),
             },
-            UserInput::Image { url } => CoreUserInput::Image { image_url: url },
-            UserInput::LocalImage { path } => CoreUserInput::LocalImage { path },
+            UserInput::Image { url, detail } => CoreUserInput::Image {
+                image_url: url,
+                detail,
+            },
+            UserInput::LocalImage { path, detail } => CoreUserInput::LocalImage { path, detail },
             UserInput::Skill { name, path } => CoreUserInput::Skill { name, path },
             UserInput::Mention { name, path } => CoreUserInput::Mention { name, path },
         }
@@ -292,8 +302,11 @@ impl From<CoreUserInput> for UserInput {
                 text,
                 text_elements: text_elements.into_iter().map(Into::into).collect(),
             },
-            CoreUserInput::Image { image_url } => UserInput::Image { url: image_url },
-            CoreUserInput::LocalImage { path } => UserInput::LocalImage { path },
+            CoreUserInput::Image { image_url, detail } => UserInput::Image {
+                url: image_url,
+                detail,
+            },
+            CoreUserInput::LocalImage { path, detail } => UserInput::LocalImage { path, detail },
             CoreUserInput::Skill { name, path } => UserInput::Skill { name, path },
             CoreUserInput::Mention { name, path } => UserInput::Mention { name, path },
             _ => unreachable!("unsupported user input variant"),