Update app.py

app.py

@@ -669,13 +669,19 @@ def _generate(
     requested_steps = steps if custom_schedule else steps + 1
 
     started = time.time()
+    # A fresh generator per stage (see `use_schedule`'s docstring) is fine on its own — each stage's noise is
+    # still a mathematically valid draw, just not a continuation of the last stage's stream. What isn't fine:
+    # reseeding to the *identical* literal seed every single stage means every stage's first draws are the
+    # exact same bits, every time — offsetting by `stage_from` (0 on a fresh/single-stage call, so this changes
+    # nothing there) means each stage actually draws a different stream.
+    effective_seed = int(seed) + stage_from
     with pk.use_schedule(
-        PIPE, steps, schedule, video_shift, audio_shift, sampler_name=sampler, seed=int(seed),
+        PIPE, steps, schedule, video_shift, audio_shift, sampler_name=sampler, seed=effective_seed,
         total_steps=total_steps, stage_from=stage_from,
     ):
-        with use_dpmpp_2s_ancestral(PIPE, int(seed), enabled=(sampler == "dpmpp_2s_ancestral")):
-            with use_dpmpp_sde_gpu(PIPE, int(seed), enabled=(sampler == "dpmpp_sde_gpu")):
-                with use_seeds_2(PIPE, int(seed), enabled=(sampler == "seeds_2")):
+        with use_dpmpp_2s_ancestral(PIPE, effective_seed, enabled=(sampler == "dpmpp_2s_ancestral")):
+            with use_dpmpp_sde_gpu(PIPE, effective_seed, enabled=(sampler == "dpmpp_sde_gpu")):
+                with use_seeds_2(PIPE, effective_seed, enabled=(sampler == "seeds_2")):
                     # Staged Denoising: resuming hands the pipeline the previous stage's own latents instead of
                     # letting `PrepareLatentsStep` draw fresh noise — both are declared-optional inputs on that
                     # step precisely for this ("used instead of the draw"), so nothing else about the call