From 597c73bc89ff4ea23101fcb97b57095aae5863ba Mon Sep 17 00:00:00 2001
From: John Lancaster <32917998+jsl12@users.noreply.github.com>
Date: Sat, 10 Oct 2026 11:15:08 -0500
Subject: [PATCH] readme update

---
 README.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/README.md b/README.md
index ff82d1c..0395541 100644
--- a/README.md
+++ b/README.md
@@ -148,6 +148,12 @@ assert set(sub["D"]) == {"E"}
 assert set(sub["E"]) == {"F"}
 ```
 
+`subgraph()` returns an independent snapshot of the successor closure, including the seeds. Only edges whose endpoints belong to that closure are retained; incoming dependencies from outside it are excluded.
+
+Unlike the earlier shared-set behavior, mutations to a subgraph do not change its parent, and later parent mutations do not change the subgraph. `sub.reverse` remains a live reverse view of the subgraph itself.
+
+Node objects and callback functions are not copied. The subgraph retains the parent's `on_add` and `on_remove` callbacks without invoking them during extraction, so any external side effects of those callbacks remain shared.
+
 ## `DAGSetView` as a Standalone Type
 
 `DAGSetView` can also be used directly as a mutable set wrapper.