diff --git a/project-specs/PESAN_KHUSUS_FLOW.md b/project-specs/PESAN_KHUSUS_FLOW.md
new file mode 100644
index 0000000..ad64da4
--- /dev/null
+++ b/project-specs/PESAN_KHUSUS_FLOW.md
@@ -0,0 +1,24 @@
+# Pesan Khusus Flow
+
+Flow untuk fitur `Pesan khusus` pada order pasien.
+
+```mermaid
+flowchart LR
+  A["Dashboard"] --> B["Orders"]
+  B --> C["Order Detail"]
+  C --> D["Pesan Khusus Page"]
+  D --> E["Isi pesan tambahan"]
+  E --> F["Submit form"]
+  F --> G["POST /Pesankhusus/add_pesan_khusus"]
+  G --> H["Redirect ke Order Detail"]
+```
+
+## Ringkas
+
+- Masuk dari daftar order.
+- Buka detail order tertentu.
+- Klik `Pesan khusus`.
+- Isi instruksi tambahan.
+- Simpan ke endpoint upstream.
+- Kembali ke detail order.
+
diff --git a/project-specs/ROUTES.md b/project-specs/ROUTES.md
index f9a056c..ae12558 100644
--- a/project-specs/ROUTES.md
+++ b/project-specs/ROUTES.md
@@ -67,3 +67,6 @@ This is a proposed route map for the rebuilt app using server-rendered pages plu
 - Use fragments for dynamic updates, not full page duplication.
 - Avoid the old app habit of making every step a separate top-level page unless it truly helps navigation.
 
+## Related Flows
+
+- [Pesan Khusus Flow](./PESAN_KHUSUS_FLOW.md)