1 files changed, 20 insertions, 0 deletions
diff --git a/libpanto/src/agent.zig b/libpanto/src/agent.zig
index 8a8a2e2..39c2f1a 100644
--- a/libpanto/src/agent.zig
+++ b/libpanto/src/agent.zig
@@ -1179,6 +1179,26 @@ pub const Stream = struct {
         self._agent._allocator.destroy(self);
     }
 
+    /// Abort this turn from the embedder side (for example, Escape in a TUI).
+    /// Provider/tool work that is currently inside `next()` cannot be unwound
+    /// until that call returns, but once control reaches the embedder this
+    /// drops every assistant/tool-result message produced by this stream before
+    /// `deinit()` has a chance to persist them. The already-persisted user
+    /// prompt (written by `Agent.run`) is intentionally kept, leaving a valid
+    /// conversation prefix with no dangling ToolUse blocks.
+    pub fn cancel(self: *Stream) void {
+        if (self._response) |ps| {
+            ps.deinit();
+            self._response = null;
+        }
+        const conv = &self._agent.conversation;
+        while (conv.messages.items.len > self._start) {
+            var msg = conv.messages.pop().?;
+            msg.deinit(conv.allocator);
+        }
+        self.state = .done;
+    }
+
     fn persistTail(self: *Stream) void {
         if (self._persisted) return;
         self._persisted = true;