Always enable original image detail on supported models (#17665)

## Summary

This PR removes `image_detail_original` as a runtime experiment and
makes original image detail available whenever the selected model
supports it.

Concretely, this change:
- drops the `image_detail_original` feature flag from the feature
registry and generated config schema
- makes tool-emitted image detail depend only on
`ModelInfo.supports_image_detail_original`
- updates `view_image` and `code_mode`/`js_repl` image emission to use
that capability check directly
- removes now-redundant experiment-specific tests and instruction
coverage
- keeps backward compatibility for existing configs by silently ignoring
a stale `features.image_detail_original` entry

The net effect is that `detail: "original"` is always available on
supported models, without requiring an experiment toggle.

codex-rs/tools/src/image_detail.rs

@@ -1,19 +1,16 @@
-use codex_features::Feature;
-use codex_features::Features;
 use codex_protocol::models::ImageDetail;
 use codex_protocol::openai_models::ModelInfo;
 
-pub fn can_request_original_image_detail(features: &Features, model_info: &ModelInfo) -> bool {
-    model_info.supports_image_detail_original && features.enabled(Feature::ImageDetailOriginal)
+pub fn can_request_original_image_detail(model_info: &ModelInfo) -> bool {
+    model_info.supports_image_detail_original
 }
 
 pub fn normalize_output_image_detail(
-    features: &Features,
     model_info: &ModelInfo,
     detail: Option<ImageDetail>,
 ) -> Option<ImageDetail> {
     match detail {
-        Some(ImageDetail::Original) if can_request_original_image_detail(features, model_info) => {
+        Some(ImageDetail::Original) if can_request_original_image_detail(model_info) => {
             Some(ImageDetail::Original)
         }
         Some(ImageDetail::Original) | Some(_) | None => None,

codex-rs/tools/src/image_detail_tests.rs

@@ -1,6 +1,4 @@
 use super::*;
-use codex_features::Feature;
-use codex_features::Features;
 use codex_protocol::models::ImageDetail;
 use codex_protocol::openai_models::ModelInfo;
 use pretty_assertions::assert_eq;
@@ -42,37 +40,26 @@ fn model_info() -> ModelInfo {
 }
 
 #[test]
-fn image_detail_original_feature_enables_explicit_original_without_force() {
+fn explicit_original_is_allowed_when_model_supports_it() {
     let model_info = model_info();
-    let mut features = Features::with_defaults();
-    features.enable(Feature::ImageDetailOriginal);
 
-    assert!(can_request_original_image_detail(&features, &model_info));
+    assert!(can_request_original_image_detail(&model_info));
     assert_eq!(
-        normalize_output_image_detail(&features, &model_info, Some(ImageDetail::Original)),
+        normalize_output_image_detail(&model_info, Some(ImageDetail::Original)),
         Some(ImageDetail::Original)
     );
     assert_eq!(
-        normalize_output_image_detail(&features, &model_info, /*detail*/ None),
+        normalize_output_image_detail(&model_info, /*detail*/ None),
         None
     );
 }
 
 #[test]
-fn explicit_original_is_dropped_without_feature_or_model_support() {
+fn explicit_original_is_dropped_without_model_support() {
     let mut model_info = model_info();
-    let features = Features::with_defaults();
-
-    assert_eq!(
-        normalize_output_image_detail(&features, &model_info, Some(ImageDetail::Original)),
-        None
-    );
-
-    let mut features = Features::with_defaults();
-    features.enable(Feature::ImageDetailOriginal);
     model_info.supports_image_detail_original = false;
     assert_eq!(
-        normalize_output_image_detail(&features, &model_info, Some(ImageDetail::Original)),
+        normalize_output_image_detail(&model_info, Some(ImageDetail::Original)),
         None
     );
 }
@@ -80,11 +67,9 @@ fn explicit_original_is_dropped_without_feature_or_model_support() {
 #[test]
 fn unsupported_non_original_detail_is_dropped() {
     let model_info = model_info();
-    let mut features = Features::with_defaults();
-    features.enable(Feature::ImageDetailOriginal);
 
     assert_eq!(
-        normalize_output_image_detail(&features, &model_info, Some(ImageDetail::Low)),
+        normalize_output_image_detail(&model_info, Some(ImageDetail::Low)),
         None
     );
 }

codex-rs/tools/src/tool_config.rs

@@ -153,7 +153,7 @@ impl ToolsConfig {
         let include_tool_suggest = features.enabled(Feature::ToolSuggest)
             && features.enabled(Feature::Apps)
             && features.enabled(Feature::Plugins);
-        let include_original_image_detail = can_request_original_image_detail(features, model_info);
+        let include_original_image_detail = can_request_original_image_detail(model_info);
         // API-key auth bypasses Codex backend entitlement/tool normalization, so
         // callers must confirm ChatGPT auth before exposing the built-in tool.
         let include_image_gen_tool = *image_generation_tool_auth_allowed

codex-rs/tools/src/tool_registry_plan_tests.rs

@@ -362,9 +362,9 @@ fn test_build_specs_enable_fanout_enables_agent_jobs_and_collab_tools() {
 }
 
 #[test]
-fn view_image_tool_omits_detail_without_original_detail_feature() {
+fn view_image_tool_omits_detail_without_original_detail_support() {
     let mut model_info = model_info();
-    model_info.supports_image_detail_original = true;
+    model_info.supports_image_detail_original = false;
     let features = Features::with_defaults();
     let available_models = Vec::new();
     let tools_config = ToolsConfig::new(&ToolsConfigParams {
@@ -392,11 +392,10 @@ fn view_image_tool_omits_detail_without_original_detail_feature() {
 }
 
 #[test]
-fn view_image_tool_includes_detail_with_original_detail_feature() {
+fn view_image_tool_includes_detail_with_original_detail_support() {
     let mut model_info = model_info();
     model_info.supports_image_detail_original = true;
-    let mut features = Features::with_defaults();
-    features.enable(Feature::ImageDetailOriginal);
+    let features = Features::with_defaults();
     let available_models = Vec::new();
     let tools_config = ToolsConfig::new(&ToolsConfigParams {
         model_info: &model_info,

codex-rs/tools/src/view_image.rs

@@ -53,7 +53,3 @@ fn view_image_output_schema() -> Value {
         "additionalProperties": false
     })
 }
-
-#[cfg(test)]
-#[path = "view_image_tests.rs"]
-mod tests;

codex-rs/tools/src/view_image_tests.rs

@@ -1,54 +0,0 @@
-use super::*;
-use crate::JsonSchema;
-use pretty_assertions::assert_eq;
-use std::collections::BTreeMap;
-
-#[test]
-fn view_image_tool_omits_detail_without_original_detail_feature() {
-    assert_eq!(
-        create_view_image_tool(ViewImageToolOptions {
-            can_request_original_image_detail: false,
-        }),
-        ToolSpec::Function(ResponsesApiTool {
-            name: "view_image".to_string(),
-            description: "View a local image from the filesystem (only use if given a full filepath by the user, and the image isn't already attached to the thread context within <image ...> tags)."
-                .to_string(),
-            strict: false,
-            defer_loading: None,
-            parameters: JsonSchema::object(BTreeMap::from([(
-                    "path".to_string(),
-                    JsonSchema::string(Some("Local filesystem path to an image file".to_string()),),
-                )]), Some(vec!["path".to_string()]), Some(false.into())),
-            output_schema: Some(view_image_output_schema()),
-        })
-    );
-}
-
-#[test]
-fn view_image_tool_includes_detail_with_original_detail_feature() {
-    assert_eq!(
-        create_view_image_tool(ViewImageToolOptions {
-            can_request_original_image_detail: true,
-        }),
-        ToolSpec::Function(ResponsesApiTool {
-            name: "view_image".to_string(),
-            description: "View a local image from the filesystem (only use if given a full filepath by the user, and the image isn't already attached to the thread context within <image ...> tags)."
-                .to_string(),
-            strict: false,
-            defer_loading: None,
-            parameters: JsonSchema::object(BTreeMap::from([
-                    (
-                        "detail".to_string(),
-                        JsonSchema::string(Some(
-                                "Optional detail override. The only supported value is `original`; omit this field for default resized behavior. Use `original` to preserve the file's original resolution instead of resizing to fit. This is important when high-fidelity image perception or precise localization is needed, especially for CUA agents.".to_string(),
-                            ),),
-                    ),
-                    (
-                        "path".to_string(),
-                        JsonSchema::string(Some("Local filesystem path to an image file".to_string()),),
-                    ),
-                ]), Some(vec!["path".to_string()]), Some(false.into())),
-            output_schema: Some(view_image_output_schema()),
-        })
-    );
-}