From 17960cc37c493f333f86deafb3495aac89e09677 Mon Sep 17 00:00:00 2001
From: Saurav Gupta <91198524+Saurav-Gupta-13@users.noreply.github.com>
Date: Thu, 2 Jul 2026 01:55:37 +0530
Subject: [PATCH] feat: auto-detect and fuse QKV for original PEFT adapters

---
 src/diffusers/loaders/peft.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/diffusers/loaders/peft.py b/src/diffusers/loaders/peft.py
index daa078bc25d5..3578a4a51ab6 100644
--- a/src/diffusers/loaders/peft.py
+++ b/src/diffusers/loaders/peft.py
@@ -225,6 +225,12 @@ def load_lora_adapter(
             if is_sai_sd_control_lora:
                 state_dict = convert_sai_sd_control_lora_state_dict_to_peft(state_dict)
 
+            # Auto-detect if the incoming state_dict expects fused QKV projections
+            # and fuse them in the model if the model supports it.
+            has_fused_qkv = any("to_qkv" in k for k in state_dict.keys())
+            if has_fused_qkv and hasattr(self, "fuse_qkv_projections"):
+                self.fuse_qkv_projections()
+
             rank = {}
             for key, val in state_dict.items():
                 # Cannot figure out rank from lora layers that don't have at least 2 dimensions.