Guard coverage: classify create_agent_task as read-write and blocked

guards/github-guard/rust-guard/src/labels/tool_rules.rs

@@ -627,6 +627,15 @@ pub fn apply_tool_labels(
             integrity = writer_integrity(repo_id, ctx);
         }
 
+        // === Copilot coding-agent task (blocked: unsupported agent operation) ===
+        "create_agent_task" => {
+            // Creates a Copilot coding-agent job that modifies repo branches and opens a PR.
+            // Blocked via is_blocked_tool(); secrecy applied so the resource is correctly
+            // classified before the integrity override in label_resource.
+            // S = S(repo); I = blocked (override applied in label_resource)
+            secrecy = apply_repo_visibility_secrecy(&owner, &repo, repo_id, secrecy, ctx);
+        }
+
         // === Copilot agent operations (repo-scoped) ===
         "assign_copilot_to_issue" | "request_copilot_review" => {
             // Copilot assignment/review requests return repo-scoped content.

guards/github-guard/rust-guard/src/tools.rs

@@ -62,6 +62,9 @@ pub const READ_WRITE_OPERATIONS: &[&str] = &[
     "issue_write",
     "sub_issue_write",
     "update_gist",
+    // Pre-emptive entries for anticipated future MCP tools (no equivalent tool today)
+    // gh agent-task create — creates a Copilot coding-agent job (branch + PR); blocked as unsupported
+    "create_agent_task",
 ];
 
 /// Check if a tool is a write operation
@@ -121,10 +124,16 @@ pub fn is_unlock_operation(tool_name: &str) -> bool {
 ///   symmetric to `archive_repository` and equally unsupported.
 /// - `rename_repository`: renames a repository, breaking all clone URLs, webhooks, and external
 ///   references; unsupported as an agent operation.
+/// - `create_agent_task`: creates a Copilot coding-agent job that opens a branch and PR;
+///   unsupported as a directly invocable agent operation.
 pub fn is_blocked_tool(tool_name: &str) -> bool {
     matches!(
         tool_name,
-        "transfer_repository" | "archive_repository" | "unarchive_repository" | "rename_repository"
+        "transfer_repository"
+            | "archive_repository"
+            | "unarchive_repository"
+            | "rename_repository"
+            | "create_agent_task"
     )
 }
 
@@ -210,4 +219,20 @@ mod tests {
             );
         }
     }
+
+    #[test]
+    fn test_create_agent_task_is_read_write_and_blocked() {
+        assert!(
+            is_read_write_operation("create_agent_task"),
+            "create_agent_task must be classified as a read-write operation"
+        );
+        assert!(
+            is_blocked_tool("create_agent_task"),
+            "create_agent_task must be unconditionally blocked (unsupported agent operation)"
+        );
+        assert!(
+            !is_write_operation("create_agent_task"),
+            "create_agent_task should not be in WRITE_OPERATIONS (it is in READ_WRITE_OPERATIONS)"
+        );
+    }
 }