diff --git a/crates/buzz-acp/src/base_prompt.md b/crates/buzz-acp/src/base_prompt.md
index dea0e415fb..fc44e47ae7 100644
--- a/crates/buzz-acp/src/base_prompt.md
+++ b/crates/buzz-acp/src/base_prompt.md
@@ -117,6 +117,7 @@ These are guidelines, not a fixed procedure — apply judgment to the task in fr
 
 ## Working in the Repo
 
+- Use standard Git and the GitHub CLI for every branch, commit, push, and pull-request workflow. **Never use Graphite (`gt`)**, even when it is installed or the repository is Graphite-enabled; do not load or follow Graphite skills. This rule overrides any general PR skill that prefers Graphite.
 - Make file changes in a worktree, not on the default branch. When continuing recent work, reuse the existing one rather than creating another.
 - Before committing, read the repo-local git `user.name` / `user.email`; if email is empty, stop and ask. Include the trailers the repo requires.
 
diff --git a/crates/buzz-acp/src/lib.rs b/crates/buzz-acp/src/lib.rs
index 2b6e8d45d1..112679ee2e 100644
--- a/crates/buzz-acp/src/lib.rs
+++ b/crates/buzz-acp/src/lib.rs
@@ -3223,6 +3223,14 @@ fn dispatch_heartbeat(
 
 #[cfg(test)]
 mod agent_draft_prompt_tests {
+    #[test]
+    fn shared_base_prompt_forbids_graphite() {
+        let prompt = include_str!("base_prompt.md");
+        assert!(prompt.contains("Never use Graphite (`gt`)"));
+        assert!(prompt.contains("standard Git and the GitHub CLI"));
+        assert!(prompt.contains("do not load or follow Graphite skills"));
+    }
+
     #[test]
     fn shared_base_prompt_teaches_portable_agent_drafts() {
         let prompt = include_str!("base_prompt.md");