fix: an unlinked H3 latent length follows the project's frames; export shows it

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -3,6 +3,8 @@
 ## [Unreleased]
 
 ### Fixed
+- An H3 latent node (Reference-to-Video / Empty AV Latent) whose `length` is not linked now follows the project's frames, instead of keeping an old typed number that made the sampler refuse the run; the settings export shows it as "follows project".
+- A view added by Shot views (POV...) no longer makes the shot look like it already has a camera move.
 - Export settings no longer prints a loader input the node no longer has (a stale `sla_enabled: on`) or SLA's settings while `sla` is off.
 
 ### Added

movie_editor/backend/builder.py

@@ -185,6 +185,10 @@ FAMILY_FRAME_GRID: dict[str, dict] = {
 }
 
 
+#: nodes that make the H3 latent template; their `length` must equal the sampler's frames.
+H3_LENGTH_NODES = frozenset({"MiniMaxH3ReferenceToVideo", "EmptyMiniMaxH3LatentAV"})
+
+
 def family_frames(family: str, frames) -> int:
     """`frames` snapped UP to `family`'s pixel-frame grid (never below one whole step)."""
     grid = FAMILY_FRAME_GRID.get(family) or FAMILY_FRAME_GRID[DEFAULT_FAMILY]
@@ -683,7 +687,19 @@ def build(object_info: dict, models_config: dict, params: dict, media: dict | No
     for s in slots:
         sid = slot_node_id[s["id"]]
         nd_s = slot_def[s["id"]]
-        for ci_name, source in (s.get("input_sources") or {}).items():
+        sources = dict(s.get("input_sources") or {})
+        # An H3 latent node has to be built for the SAME length the sampler is given or the run
+        # dies at sampling ("latent node's `length` must be the SAME ... frame count"). Left
+        # unlinked it keeps whatever number it was last typed with, so changing the project's
+        # length silently stranded it. Unlinked = follows the project; a choice stays a choice.
+        if (s.get("node_class") in H3_LENGTH_NODES and not sources.get("length")
+                and "frames" in graph and "length" in (graph[sid].get("inputs") or {})
+                and not isinstance(graph[sid]["inputs"]["length"], list)):
+            was = graph[sid]["inputs"]["length"]
+            sources["length"] = "core:frames:0"
+            report["wired"].append(f"{s.get('node_class')} length ({was}) -> Project frames "
+                                   f"({graph['frames']['inputs'].get('value')})")
+        for ci_name, source in sources.items():
             ci_name = _canonical_input(nd_s, ci_name)
             if not source or source == "auto":
                 continue

movie_editor/backend/settings_card.py

@@ -550,6 +550,11 @@ def _sampling_sections(studio_inputs: dict, sampler_inputs: dict) -> list:
     return out
 
 
+def _h3_length_nodes():
+    from .builder import H3_LENGTH_NODES
+    return H3_LENGTH_NODES
+
+
 def collect(models: dict, host: dict, *, project_name=None, version=None,
             codename=None, render=None, studio_inputs=None, sampler_inputs=None) -> dict:
     """The card's content, as data. Rendering is a separate step so this is testable."""
@@ -580,6 +585,12 @@ def collect(models: dict, host: dict, *, project_name=None, version=None,
                 rows.append((name, ""))
                 rows.extend((f"    {k}", v) for k, v in listed)
                 continue
+            if (name == "length" and slot.get("node_class") in _h3_length_nodes()
+                    and not (slot.get("input_sources") or {}).get("length")
+                    and (render or {}).get("frames per scene")):
+                # The builder links an unlinked H3 latent length to the project's frames, so
+                # the typed number is not what runs.
+                value = f"follows project ({render['frames per scene']})"
             rows.append((name, _short(value)))
         sections.append({
             "title": str(title),

movie_editor/tests/test_builder.py

@@ -1613,3 +1613,28 @@ def test_studio_skips_its_own_enhancement_when_nothing_reads_its_conditioning():
                 "slots": [{"id": "r2v", "node_class": "R2V", "inputs": {}, "wires": {}}],
                 "core_overrides": {"sampler": {"positive": "out:r2v:CONDITIONING"}}}
     assert rf_of(bypassed)["prompt_enhance_scenes"] is False
+
+
+def _lat(graph):
+    return next(n for n in graph.values() if n["class_type"] == "EmptyMiniMaxH3LatentAV")
+
+
+def test_an_unlinked_h3_latent_length_follows_the_projects_frames():
+    """The project length was changed to 362 and the latent node kept its typed 260: the
+    sampler then refuses the run. Unlinked = follows the project."""
+    models = {"model_family": "minimax_h3", "slots": [
+        dict(s, inputs={"length": 260}) if s["id"] == "lat" else s for s in H3_MODELS["slots"]]}
+    graph, report = builder.build(H3_OI, models, {"prompt": "a shot", "num_frames_per_scene": 362})
+    length = _lat(graph)["inputs"]["length"]
+    assert isinstance(length, list) and length[0] == "frames"
+    assert graph["frames"]["inputs"]["value"] == 362
+    assert any("length (260)" in w and "362" in w for w in report["wired"]), report["wired"]
+
+
+def test_a_linked_h3_latent_length_is_left_as_the_user_linked_it():
+    models = {"model_family": "minimax_h3", "slots": [
+        dict(s, inputs={"length": 260}, input_sources={"length": "core:frames:0"})
+        if s["id"] == "lat" else s for s in H3_MODELS["slots"]]}
+    graph, report = builder.build(H3_OI, models, {"prompt": "a shot", "num_frames_per_scene": 362})
+    assert _lat(graph)["inputs"]["length"][0] == "frames"
+    assert not any("length (260)" in w for w in report["wired"])

tests/test_settings_card_noise.py

@@ -254,3 +254,15 @@ def test_a_model_slot_does_not_print_a_stale_input_or_sla_settings_with_sla_off(
     rows = dict(next(s for s in sc.collect({"slots": [slot]}, {})["sections"]
                      if s["title"] == "Diffusion model")["rows"])
     assert "sla_sparsity" in rows and "sla_enabled" not in rows
+
+
+def test_an_unlinked_h3_latent_length_is_shown_as_following_the_project():
+    slot = {"id": "r", "node_class": "MiniMaxH3ReferenceToVideo", "label": "R2V",
+            "inputs": {"width": 1344, "length": 260}, "input_sources": {"length": ""}}
+    card = sc.collect({"slots": [slot]}, {}, render={"frames per scene": 362})
+    rows = dict(next(s for s in card["sections"] if s["title"] == "R2V")["rows"])
+    assert rows["length"] == "follows project (362)"
+    slot["input_sources"]["length"] = "core:frames:0"
+    rows = dict(next(s for s in sc.collect({"slots": [slot]}, {}, render={"frames per scene": 362})["sections"]
+                     if s["title"] == "R2V")["rows"])
+    assert rows["length"] != "follows project (362)"