Avoid rendering generated images twice (#34378)

## What changed

- Tell the model that generated images are already displayed to the user and should not be repeated as Markdown images or file links.
- Keep generated-image artifact paths and output hints owned by the image generation extension.
- Centralize the availability check for the image generation tool across feature, provider, namespace-tool, model modality, and authentication requirements.

## Testing

- Verify artifact paths sanitize session and call identifiers.
- Verify the model-facing output hint reports that the generated image is already displayed.

GitOrigin-RevId: 6c865b6a96d6a71bb2c33246d1518a00e7c8b840

codex-rs/core/src/context/image_generation_instructions.rs

@@ -1,22 +0,0 @@
-use std::fmt::Display;
-
-/// Maximum size of the extension's model-facing generated-image path hint.
-const MAX_IMAGE_GENERATION_OUTPUT_HINT_BYTES: usize = 1024;
-
-/// Returns the extension's model-facing hint, or omits it if the path makes it too large.
-pub fn extension_image_generation_output_hint(
-    image_output_dir: impl Display,
-    image_output_path: impl Display,
-) -> Option<String> {
-    let hint = image_generation_hint(image_output_dir, image_output_path);
-    (hint.len() <= MAX_IMAGE_GENERATION_OUTPUT_HINT_BYTES).then_some(hint)
-}
-
-fn image_generation_hint(
-    image_output_dir: impl Display,
-    image_output_path: impl Display,
-) -> String {
-    format!(
-        "Generated images are saved to {image_output_dir} as {image_output_path} by default.\nIf you need to use a generated image at another path, copy it and leave the original in place unless the user explicitly asks you to delete it."
-    )
-}

codex-rs/core/src/context/mod.rs

@@ -10,7 +10,6 @@ mod environment_context;
 mod environments_instructions;
 mod guardian_followup_review_reminder;
 mod hook_additional_context;
-mod image_generation_instructions;
 mod inter_agent_completion_message;
 mod internal_model_context;
 mod legacy_apply_patch_exec_command_warning;
@@ -51,7 +50,6 @@ pub(crate) use current_time_reminder::CurrentTimeReminder;
 pub(crate) use environments_instructions::EnvironmentsInstructions;
 pub(crate) use guardian_followup_review_reminder::GuardianFollowupReviewReminder;
 pub(crate) use hook_additional_context::HookAdditionalContext;
-pub use image_generation_instructions::extension_image_generation_output_hint;
 pub(crate) use inter_agent_completion_message::InterAgentCompletionMessage;
 pub use internal_model_context::InternalContextSource;
 pub use internal_model_context::InternalModelContextFragment;

codex-rs/core/src/context_manager/history_tests.rs

@@ -1047,7 +1047,6 @@ fn drop_last_n_user_turns_trims_context_updates_above_rolled_back_turn() {
         assistant_msg("session prefix item"),
         user_input_text_msg("turn 1 user"),
         assistant_msg("turn 1 assistant"),
-        developer_msg("Generated images are saved to /tmp as /tmp/image-1.png by default."),
         developer_msg(&format!(
             "{APPS_INSTRUCTIONS_OPEN_TAG}\nROLLED_BACK_APPS_INSTRUCTIONS"
         )),
@@ -1078,7 +1077,6 @@ fn drop_last_n_user_turns_trims_context_updates_above_rolled_back_turn() {
             assistant_msg("session prefix item"),
             user_input_text_msg("turn 1 user"),
             assistant_msg("turn 1 assistant"),
-            developer_msg("Generated images are saved to /tmp as /tmp/image-1.png by default."),
         ]
     );
     assert_eq!(

codex-rs/core/src/lib.rs

@@ -98,7 +98,6 @@ pub(crate) use skills::injection;
 pub(crate) use skills::maybe_emit_implicit_skill_invocation;
 pub(crate) use skills::skills_load_input_from_config;
 mod stream_events_utils;
-pub use stream_events_utils::image_generation_artifact_path;
 pub mod test_support;
 mod unified_exec;
 pub mod windows_sandbox;

codex-rs/core/src/stream_events_utils.rs

@@ -25,44 +25,12 @@ use codex_protocol::models::MessagePhase;
 use codex_protocol::models::ResponseInputItem;
 use codex_protocol::models::ResponseItem;
 use codex_rollout::state_db;
-use codex_utils_absolute_path::AbsolutePathBuf;
 use codex_utils_stream_parser::strip_proposed_plan_blocks;
 use futures::Future;
 use tracing::debug;
 use tracing::instrument;
 use tracing::warn;
 
-const GENERATED_IMAGE_ARTIFACTS_DIR: &str = "generated_images";
-
-/// Returns the host-owned default artifact path for a generated image.
-pub fn image_generation_artifact_path(
-    codex_home: &AbsolutePathBuf,
-    session_id: &str,
-    call_id: &str,
-) -> AbsolutePathBuf {
-    let sanitize = |value: &str| {
-        let mut sanitized: String = value
-            .chars()
-            .map(|ch| {
-                if ch.is_ascii_alphanumeric() || ch == '-' || ch == '_' {
-                    ch
-                } else {
-                    '_'
-                }
-            })
-            .collect();
-        if sanitized.is_empty() {
-            sanitized = "generated_image".to_string();
-        }
-        sanitized
-    };
-
-    codex_home
-        .join(GENERATED_IMAGE_ARTIFACTS_DIR)
-        .join(sanitize(session_id))
-        .join(format!("{}.png", sanitize(call_id)))
-}
-
 fn strip_hidden_assistant_markup(text: &str, plan_mode: bool) -> String {
     let (without_citations, _) = strip_citations(text);
     if plan_mode {

codex-rs/core/src/tools/handlers/extension_tools.rs

@@ -429,11 +429,6 @@ mod tests {
     async fn image_generation_publication_preserves_extension_saved_path() {
         let (session, turn, rx) = crate::session::tests::make_session_and_context_with_rx().await;
         let expected_path = test_path_buf("/tmp/extension-claimed.png").abs();
-        let default_path = crate::stream_events_utils::image_generation_artifact_path(
-            &turn.config.codex_home,
-            &session.thread_id.to_string(),
-            "call-image",
-        );
         let emitter = CoreTurnItemEmitter {
             session: Arc::downgrade(&session),
             turn: Arc::downgrade(&turn),
@@ -498,6 +493,5 @@ mod tests {
 
         assert_eq!(started_item, expected_started_item);
         assert_eq!(completed_item, expected_completed_item);
-        assert!(!default_path.exists());
     }
 }

codex-rs/core/src/tools/spec_plan.rs

@@ -364,33 +364,36 @@ fn agent_jobs_worker_tools_enabled(turn_context: &TurnContext) -> bool {
         )
 }
 
-fn image_generation_runtime_enabled(turn_context: &TurnContext) -> bool {
-    (turn_context
-        .provider
-        .info()
-        .uses_openai_actor_authorization()
-        || (turn_context.provider.info().requires_openai_auth
-            && turn_context
-                .auth_manager
-                .as_deref()
-                .is_some_and(AuthManager::current_auth_uses_codex_backend)))
-        && turn_context.provider.capabilities().image_generation
-        && turn_context
-            .model_info
-            .input_modalities
-            .contains(&InputModality::Image)
-}
-
-fn standalone_image_generation_model_visible(turn_context: &TurnContext) -> bool {
-    if !image_generation_runtime_enabled(turn_context) || !namespace_tools_enabled(turn_context) {
-        return false;
-    }
-
-    turn_context
+fn image_generation_available(turn_context: &TurnContext) -> bool {
+    if !turn_context
         .config
         .features
         .get()
         .enabled(Feature::ImageGeneration)
+    {
+        return false;
+    }
+
+    let capabilities = turn_context.provider.capabilities();
+    if !capabilities.image_generation || !capabilities.namespace_tools {
+        return false;
+    }
+
+    if !turn_context
+        .model_info
+        .input_modalities
+        .contains(&InputModality::Image)
+    {
+        return false;
+    }
+
+    let provider = turn_context.provider.info();
+    provider.uses_openai_actor_authorization()
+        || (provider.requires_openai_auth
+            && turn_context
+                .auth_manager
+                .as_deref()
+                .is_some_and(AuthManager::current_auth_uses_codex_backend))
 }
 
 fn wait_agent_timeout_options(turn_context: &TurnContext) -> WaitAgentTimeoutOptions {
@@ -996,7 +999,7 @@ fn append_extension_tool_executors(
             continue;
         }
         if tool_name == ToolName::namespaced(IMAGE_GEN_NAMESPACE, IMAGEGEN_TOOL_NAME)
-            && !standalone_image_generation_model_visible(turn_context)
+            && !image_generation_available(turn_context)
         {
             continue;
         }