fix: introduce EventMsg::TurnAborted (#2365)

Introduces `EventMsg::TurnAborted` that should be sent in response to
`Op::Interrupt`.

In the MCP server, updates the handling of a
`ClientRequest::InterruptConversation` request such that it sends the
`Op::Interrupt` but does not respond to the request until it sees an
`EventMsg::TurnAborted`.

codex-rs/exec/src/event_processor_with_human_output.rs

@@ -21,6 +21,7 @@ use codex_core::protocol::PatchApplyBeginEvent;
 use codex_core::protocol::PatchApplyEndEvent;
 use codex_core::protocol::SessionConfiguredEvent;
 use codex_core::protocol::TaskCompleteEvent;
+use codex_core::protocol::TurnAbortReason;
 use codex_core::protocol::TurnDiffEvent;
 use owo_colors::OwoColorize;
 use owo_colors::Style;
@@ -522,6 +523,14 @@ impl EventProcessor for EventProcessorWithHumanOutput {
             EventMsg::GetHistoryEntryResponse(_) => {
                 // Currently ignored in exec output.
             }
+            EventMsg::TurnAborted(abort_reason) => match abort_reason.reason {
+                TurnAbortReason::Interrupted => {
+                    ts_println!(self, "task interrupted");
+                }
+                TurnAbortReason::Replaced => {
+                    ts_println!(self, "task aborted: replaced by a new task");
+                }
+            },
             EventMsg::ShutdownComplete => return CodexStatus::Shutdown,
         }
         CodexStatus::Running