From 29d13e331134418316e882446be21aac6aeb0878 Mon Sep 17 00:00:00 2001
From: Khairul Kabir <250204754+khairulkabir1661@users.noreply.github.com>
Date: Thu, 24 Sep 2026 12:23:28 -0700
Subject: [PATCH] [CI][Diffusion] Add tiny model builder for
 StableDiffusion3Pipeline (#6423)

Signed-off-by: khairulkabir1661 <khairulkabir1661@users.noreply.github.com>
Co-authored-by: khairulkabir1661 <khairulkabir1661@users.noreply.github.com>
---
 .../diffusion/diff_model_builders.py          | 22 +++++++++++++++++++
 tests/model_tests/diffusion/model_settings.py |  5 +++++
 tests/model_tests/diffusion/test_alignment.py |  1 -
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/tests/model_tests/diffusion/diff_model_builders.py b/tests/model_tests/diffusion/diff_model_builders.py
index 4ef3f6c33..cf8b4c92c 100644
--- a/tests/model_tests/diffusion/diff_model_builders.py
+++ b/tests/model_tests/diffusion/diff_model_builders.py
@@ -256,6 +256,28 @@ def tiny_flux_kontext_builder() -> str:
     )
 
 
+def _shrink_sd3_transformer(config: dict) -> dict:
+    config["num_layers"] = 2
+    config["attention_head_dim"] = 32
+    config["num_attention_heads"] = 4
+    config["caption_projection_dim"] = 128
+    config["dual_attention_layers"] = [0]
+    return config
+
+
+def tiny_sd3_builder() -> str:
+    return build_tiny_from_configs(
+        "StableDiffusion3Pipeline",
+        "stabilityai/stable-diffusion-3.5-medium",
+        transform={
+            "text_encoder": _shrink_flux_clip_text_encoder,
+            "text_encoder_2": _shrink_flux_clip_text_encoder,
+            "text_encoder_3": _shrink_flux_t5_text_encoder,
+            "transformer": _shrink_sd3_transformer,
+        },
+    )
+
+
 def tiny_flux2_builder() -> str:
     def shrink_text_encoder(config: dict) -> dict:
         config["tie_word_embeddings"] = False
diff --git a/tests/model_tests/diffusion/model_settings.py b/tests/model_tests/diffusion/model_settings.py
index 8c5955c8d..85ec720be 100644
--- a/tests/model_tests/diffusion/model_settings.py
+++ b/tests/model_tests/diffusion/model_settings.py
@@ -146,4 +146,9 @@ DIFFUSION_TEST_SETTINGS = {
         builder=diff_model_builders.tiny_qwen_image_edit_plus_builder,
         supported_tasks=[DiffusionTasks.IMAGE_TO_IMAGE],
     ),
+    "StableDiffusion3Pipeline": DiffusionModelTestOpts(
+        model="stabilityai/stable-diffusion-3.5-medium",
+        builder=diff_model_builders.tiny_sd3_builder,
+        supported_tasks=[DiffusionTasks.TEXT_TO_IMAGE],
+    ),
 }
diff --git a/tests/model_tests/diffusion/test_alignment.py b/tests/model_tests/diffusion/test_alignment.py
index 6c39d702c..c2489777a 100644
--- a/tests/model_tests/diffusion/test_alignment.py
+++ b/tests/model_tests/diffusion/test_alignment.py
@@ -56,7 +56,6 @@ EXCLUDED_MODELS = [
     "MingImageDiffusionPipeline",
     "MingImageLayeredDiffusionPipeline",
     "InternVLAA1Pipeline",
-    "StableDiffusion3Pipeline",
     "HunyuanImage3ForCausalMM",
     "ErnieImagePipeline",
     "NextStep11Pipeline",