Stop retrying turns with invalid tool images (#34380)

## What changed

Remove the fallback that replaced image content in the latest tool output with
`Invalid image` and retried the model request. Invalid-image responses now use
the existing bad-request error path without modifying conversation history.

GitOrigin-RevId: f4ea782f16c5451feb261694caa73b77f24c3e4e

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

@@ -202,40 +202,6 @@ impl ContextManager {
         self.world_state_baseline = None;
     }
 
-    /// Replace image content in the last turn if it originated from a tool output.
-    /// Returns true when a tool image was replaced, false otherwise.
-    pub(crate) fn replace_last_turn_images(&mut self, placeholder: &str) -> bool {
-        let Some(index) = self.items.iter().rposition(|item| {
-            matches!(item, ResponseItem::FunctionCallOutput { .. }) || is_user_turn_boundary(item)
-        }) else {
-            return false;
-        };
-
-        match &mut self.items[index] {
-            ResponseItem::FunctionCallOutput { output, .. } => {
-                let Some(content_items) = output.content_items_mut() else {
-                    return false;
-                };
-                let mut replaced = false;
-                let placeholder = placeholder.to_string();
-                for item in content_items.iter_mut() {
-                    if matches!(item, FunctionCallOutputContentItem::InputImage { .. }) {
-                        *item = FunctionCallOutputContentItem::InputText {
-                            text: placeholder.clone(),
-                        };
-                        replaced = true;
-                    }
-                }
-                if replaced {
-                    self.history_version = self.history_version.saturating_add(1);
-                }
-                replaced
-            }
-            ResponseItem::Message { .. } => false,
-            _ => false,
-        }
-    }
-
     /// Drop the last `num_turns` instruction turns from this history.
     ///
     /// Instruction turns are history messages that should behave like a new prompt boundary:

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

@@ -815,68 +815,6 @@ fn remove_first_item_removes_matching_call_for_output() {
     assert_eq!(h.raw_items(), vec![]);
 }
 
-#[test]
-fn replace_last_turn_images_replaces_tool_output_images() {
-    let items = vec![
-        user_input_text_msg("hi"),
-        ResponseItem::FunctionCallOutput {
-            id: None,
-            call_id: "call-1".to_string(),
-            output: FunctionCallOutputPayload {
-                body: FunctionCallOutputBody::ContentItems(vec![
-                    FunctionCallOutputContentItem::InputImage {
-                        image_url: "data:image/png;base64,AAA".to_string(),
-                        detail: Some(DEFAULT_IMAGE_DETAIL),
-                    },
-                ]),
-                success: Some(true),
-            },
-            internal_chat_message_metadata_passthrough: None,
-        },
-    ];
-    let mut history = create_history_with_items(items);
-
-    assert!(history.replace_last_turn_images("Invalid image"));
-
-    assert_eq!(
-        history.raw_items(),
-        vec![
-            user_input_text_msg("hi"),
-            ResponseItem::FunctionCallOutput {
-                id: None,
-                call_id: "call-1".to_string(),
-                output: FunctionCallOutputPayload {
-                    body: FunctionCallOutputBody::ContentItems(vec![
-                        FunctionCallOutputContentItem::InputText {
-                            text: "Invalid image".to_string(),
-                        },
-                    ]),
-                    success: Some(true),
-                },
-                internal_chat_message_metadata_passthrough: None,
-            },
-        ]
-    );
-}
-
-#[test]
-fn replace_last_turn_images_does_not_touch_user_images() {
-    let items = vec![ResponseItem::Message {
-        id: None,
-        role: "user".to_string(),
-        content: vec![ContentItem::InputImage {
-            image_url: "data:image/png;base64,AAA".to_string(),
-            detail: Some(DEFAULT_IMAGE_DETAIL),
-        }],
-        phase: None,
-        internal_chat_message_metadata_passthrough: None,
-    }];
-    let mut history = create_history_with_items(items.clone());
-
-    assert!(!history.replace_last_turn_images("Invalid image"));
-    assert_eq!(history.raw_items(), items);
-}
-
 #[test]
 fn remove_first_item_handles_local_shell_pair() {
     let items = vec![

codex-rs/core/src/session/turn.rs

@@ -432,16 +432,6 @@ pub(crate) async fn run_turn(
                 return Err(err);
             }
             Err(codex_error @ CodexErr::InvalidImageRequest()) => {
-                {
-                    let mut state = sess.state.lock().await;
-                    error_or_panic(
-                        "Invalid image detected; sanitizing tool output to prevent poisoning",
-                    );
-                    if state.history.replace_last_turn_images("Invalid image") {
-                        continue;
-                    }
-                }
-
                 sess.track_turn_codex_error(turn_context.as_ref(), &codex_error);
                 let error = CodexErrorInfo::BadRequest;
                 sess.emit_turn_error_lifecycle(turn_context.as_ref(), error.clone())