make codex better at git (#10145)

adds basic git context to the session prefix so the model can anchor git
actions and be a bit more version-aware. structured it in a
multiroot-friendly shape even though we only have one root today

codex-rs/core/src/codex.rs

@@ -119,6 +119,7 @@ use crate::error::Result as CodexResult;
 use crate::exec::StreamOutput;
 use crate::exec_policy::ExecPolicyUpdateError;
 use crate::feedback_tags;
+use crate::git_info::get_git_repo_root;
 use crate::instructions::UserInstructions;
 use crate::mcp::CODEX_APPS_MCP_SERVER_NAME;
 use crate::mcp::auth::compute_auth_statuses;
@@ -531,7 +532,6 @@ pub(crate) struct TurnContext {
     pub(crate) truncation_policy: TruncationPolicy,
     pub(crate) dynamic_tools: Vec<DynamicToolSpec>,
 }
-
 impl TurnContext {
     pub(crate) fn resolve_path(&self, path: Option<String>) -> PathBuf {
         path.as_ref()
@@ -3406,7 +3406,9 @@ pub(crate) async fn run_turn(
     // many turns, from the perspective of the user, it is a single turn.
     let turn_diff_tracker = Arc::new(tokio::sync::Mutex::new(TurnDiffTracker::new()));
 
-    let mut client_session = turn_context.client.new_session();
+    let mut client_session = turn_context
+        .client
+        .new_session(Some(turn_context.cwd.clone()));
 
     loop {
         // Note that pending_input would be something like a message the user
@@ -4469,8 +4471,6 @@ pub(super) fn get_last_assistant_message_from_turn(responses: &[ResponseItem]) -
 
 #[cfg(test)]
 pub(crate) use tests::make_session_and_context;
-
-use crate::git_info::get_git_repo_root;
 #[cfg(test)]
 pub(crate) use tests::make_session_and_context_with_rx;