diff --git a/crates/vite_task_graph/run-config.ts b/crates/vite_task_graph/run-config.ts
index 4b0c4c48..0ab58364 100644
--- a/crates/vite_task_graph/run-config.ts
+++ b/crates/vite_task_graph/run-config.ts
@@ -1,3 +1,5 @@
+// This file is auto-generated by `cargo test`. Do not edit manually.
+
 export type Task = {
   /**
    * The command to run for the task.
diff --git a/crates/vite_task_graph/src/config/user.rs b/crates/vite_task_graph/src/config/user.rs
index d8d784d6..60feb652 100644
--- a/crates/vite_task_graph/src/config/user.rs
+++ b/crates/vite_task_graph/src/config/user.rs
@@ -204,37 +204,52 @@ impl UserRunConfig {
     #[expect(clippy::disallowed_types, reason = "test code uses std types for convenience")]
     pub fn generate_ts_definition() -> String {
         use std::{
+            any::TypeId,
+            collections::HashSet,
             io::Write,
             process::{Command, Stdio},
         };
 
         use ts_rs::TypeVisitor;
 
-        struct DeclCollector(Vec<String>);
+        struct DeclCollector {
+            decls: Vec<String>,
+            visited: HashSet<TypeId>,
+        }
 
         impl TypeVisitor for DeclCollector {
             fn visit<T: TS + 'static + ?Sized>(&mut self) {
+                if !self.visited.insert(TypeId::of::<T>()) {
+                    return;
+                }
                 // Only collect declarations from types that are exportable
                 // (i.e., have an output path - built-in types like HashMap don't)
                 if T::output_path().is_some() {
-                    self.0.push(T::decl());
+                    self.decls.push(T::decl());
                 }
+                // Recursively visit dependencies of T
+                T::visit_dependencies(self);
             }
         }
 
-        let mut collector = DeclCollector(Vec::new());
+        let mut collector = DeclCollector { decls: Vec::new(), visited: HashSet::new() };
         Self::visit_dependencies(&mut collector);
 
         // Sort declarations for deterministic output order
-        collector.0.sort();
+        collector.decls.sort();
+
+        // Header
+        let mut types: String =
+            "// This file is auto-generated by `cargo test`. Do not edit manually.\n\n".into();
 
         // Export all types
-        let mut types: String = collector
-            .0
+        let dep_types: String = collector
+            .decls
             .iter()
             .map(|decl| vite_str::format!("export {decl}"))
             .collect::<Vec<_>>()
             .join("\n\n");
+        types.push_str(&dep_types);
 
         // Export the main type
         types.push_str("\n\nexport ");