From 0e6976a0ae1e21062f697e294042d4edab8c581f Mon Sep 17 00:00:00 2001
From: Mr-Neutr0n <64578610+Mr-Neutr0n@users.noreply.github.com>
Date: Wed, 11 Feb 2026 19:51:25 +0530
Subject: [PATCH] fix: prevent division by zero in trajectory imitation loss at
 last step

---
 diffsynth/diffusion/loss.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/diffsynth/diffusion/loss.py b/diffsynth/diffusion/loss.py
index 14fdfd3..4da195f 100644
--- a/diffsynth/diffusion/loss.py
+++ b/diffsynth/diffusion/loss.py
@@ -91,7 +91,7 @@ class TrajectoryImitationLoss(torch.nn.Module):
                 progress_id_teacher = torch.argmin((timesteps_teacher - pipe.scheduler.timesteps[progress_id + 1]).abs())
                 latents_ = trajectory_teacher[progress_id_teacher]
             
-            target = (latents_ - inputs_shared["latents"]) / (sigma_ - sigma)
+            target = (latents_ - inputs_shared["latents"]) / (sigma_ - sigma).clamp(min=1e-6)
             loss = loss + torch.nn.functional.mse_loss(noise_pred.float(), target.float()) * pipe.scheduler.training_weight(timestep)
         return loss