Rescue chat completion changes (#1846)

https://github.com/openai/codex/pull/1835 has some messed up history.

This adds support for streaming chat completions, which is useful for ollama. We should probably take a very skeptical eye to the code introduced in this PR.

---------

Co-authored-by: Ahmed Ibrahim <aibrahim@openai.com>

codex-rs/core/src/models.rs

@@ -45,6 +45,8 @@ pub enum ResponseItem {
     Reasoning {
         id: String,
         summary: Vec<ReasoningItemReasoningSummary>,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        content: Option<Vec<ReasoningItemContent>>,
         encrypted_content: Option<String>,
     },
     LocalShellCall {
@@ -136,6 +138,12 @@ pub enum ReasoningItemReasoningSummary {
     SummaryText { text: String },
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+#[serde(tag = "type", rename_all = "snake_case")]
+pub enum ReasoningItemContent {
+    ReasoningText { text: String },
+}
+
 impl From<Vec<InputItem>> for ResponseInputItem {
     fn from(items: Vec<InputItem>) -> Self {
         Self::Message {