diff --git a/shotcut/agent-harness/cli_anything/shotcut/core/timeline.py b/shotcut/agent-harness/cli_anything/shotcut/core/timeline.py
index 3bb2081e5..74879dcae 100644
--- a/shotcut/agent-harness/cli_anything/shotcut/core/timeline.py
+++ b/shotcut/agent-harness/cli_anything/shotcut/core/timeline.py
@@ -152,7 +152,11 @@ def _entry_duration_frames(session: Session, entry: dict) -> int:
     out_point = entry.get("out")
     if not out_point:
         raise RuntimeError("Absolute timeline placement requires clips with finite out points")
-    return parse_time_input(out_point, fps_num, fps_den) - parse_time_input(in_point, fps_num, fps_den)
+    return (
+        parse_time_input(out_point, fps_num, fps_den)
+        - parse_time_input(in_point, fps_num, fps_den)
+        + 1
+    )
 
 
 def _absolute_insertion_point(
@@ -187,7 +191,11 @@ def _absolute_insertion_point(
             if out_tc is None:
                 prod = mlt_xml.find_element_by_id(session.root, child.get("producer", ""))
                 out_tc = prod.get("out", "00:00:00.000") if prod is not None else "00:00:00.000"
-            duration = parse_time_input(out_tc, fps_num, fps_den) - parse_time_input(in_tc, fps_num, fps_den)
+            duration = (
+                parse_time_input(out_tc, fps_num, fps_den)
+                - parse_time_input(in_tc, fps_num, fps_den)
+                + 1
+            )
             start = timeline_cursor
             end = start + duration
             if target == start:
@@ -249,12 +257,13 @@ def _update_tractor_out(session: Session) -> None:
                         out_tc = "00:00:00.000"
                 track_frames += parse_time_input(out_tc, fps_num, fps_den)
                 track_frames -= parse_time_input(in_tc, fps_num, fps_den)
+                track_frames += 1
             elif child.tag == "blank":
                 track_frames += parse_time_input(child.get("length", "00:00:00.000"), fps_num, fps_den)
 
         max_frames = max(max_frames, track_frames)
 
-    out_tc = frames_to_timecode(max_frames, fps_num, fps_den) if max_frames > 0 else "00:00:00.000"
+    out_tc = frames_to_timecode(max_frames - 1, fps_num, fps_den) if max_frames > 0 else "00:00:00.000"
     mlt_xml.set_tractor_out(session.root, out_tc)
 
     # Sync background producer and playlist entry to match — melt ignores
@@ -263,7 +272,7 @@ def _update_tractor_out(session: Session) -> None:
     if bg_producer is not None:
         bg_producer.set("out", out_tc)
         mlt_xml.set_property(bg_producer, "length",
-                             frames_to_timecode(max_frames + 1, fps_num, fps_den)
+                             frames_to_timecode(max_frames, fps_num, fps_den)
                              if max_frames > 0 else "00:00:00.040")
     bg_playlist = mlt_xml.find_element_by_id(session.root, "background")
     if bg_playlist is not None:
@@ -579,7 +588,7 @@ def remove_clip(session: Session, track_index: int, clip_index: int,
         playlist.remove(target_child)
         in_frames = parse_time_input(in_tc, fps_num, fps_den)
         out_frames = parse_time_input(out_tc, fps_num, fps_den)
-        duration_frames = out_frames - in_frames
+        duration_frames = out_frames - in_frames + 1
         if duration_frames > 0:
             duration_tc = frames_to_timecode(duration_frames, fps_num, fps_den)
             blank = ET.Element("blank")
@@ -748,8 +757,19 @@ def split_clip(session: Session, track_index: int, clip_index: int,
                 if old_out is None:
                     raise RuntimeError("Cannot split clip without out point")
 
-                # First part: original in → split point (AFTER transition restore)
-                child.set("out", at)
+                old_in_frames = parse_time_input(old_in, fps_num, fps_den)
+                old_out_frames = parse_time_input(old_out, fps_num, fps_den)
+                split_frames = parse_time_input(at, fps_num, fps_den)
+                if split_frames <= old_in_frames:
+                    raise ValueError("Split point must be after the clip in point")
+                if split_frames > old_out_frames:
+                    raise ValueError("Split point must not exceed the clip out point")
+
+                first_out = frames_to_timecode(split_frames - 1, fps_num, fps_den)
+
+                # MLT out-points are inclusive, so the first half must end on
+                # the frame immediately before the split point.
+                child.set("out", first_out)
 
                 # Second part: split point → original out
                 # Create a copy of the timeline chain
@@ -782,7 +802,7 @@ def split_clip(session: Session, track_index: int, clip_index: int,
                     "track_index": track_index,
                     "clip_index": clip_index,
                     "at": at,
-                    "first_clip": {"chain_id": producer_id, "in": old_in, "out": at},
+                    "first_clip": {"chain_id": producer_id, "in": old_in, "out": first_out},
                     "second_clip": {"chain_id": new_chain_id, "in": at, "out": old_out},
                 }
             entry_count += 1
diff --git a/shotcut/agent-harness/cli_anything/shotcut/tests/test_core.py b/shotcut/agent-harness/cli_anything/shotcut/tests/test_core.py
index ce2c2cb7b..fd34bd574 100644
--- a/shotcut/agent-harness/cli_anything/shotcut/tests/test_core.py
+++ b/shotcut/agent-harness/cli_anything/shotcut/tests/test_core.py
@@ -109,6 +109,30 @@ class TestMltXml:
         assert parsed.tag == "mlt"
         assert parsed.find("profile").get("width") == "1920"
 
+    def test_write_mlt_normalizes_late_media_nodes(self, tmp_path):
+        root = create_blank_project(PROFILE_HD1080)
+        late_chain = ET.Element("chain")
+        late_chain.set("id", "late_chain")
+        late_chain.set("in", "00:00:00.000")
+        late_chain.set("out", "00:00:01.000")
+        set_property(late_chain, "resource", "/tmp/fake.mp4")
+        set_property(late_chain, "mlt_service", "avformat-novalidate")
+        root.append(late_chain)
+
+        tmpfile = str(tmp_path / "ordered.mlt")
+        write_mlt(root, tmpfile)
+        parsed = parse_mlt(tmpfile)
+        children = list(parsed)
+        first_playlist_or_tractor = min(
+            idx for idx, child in enumerate(children) if child.tag in ("playlist", "tractor")
+        )
+        late_idx = next(
+            idx
+            for idx, child in enumerate(children)
+            if child.tag == "chain" and child.get("id") == "late_chain"
+        )
+        assert late_idx < first_playlist_or_tractor
+
     def test_properties(self):
         import xml.etree.ElementTree as ET
         elem = ET.Element("producer")
@@ -449,6 +473,15 @@ class TestTimeline:
                  if c.get("clip_index") is not None]
         assert len(clips) == 0
 
+    def test_remove_clip_without_ripple_preserves_inclusive_duration(self, session_with_track, dummy_file):
+        clip_id = media_mod.import_media(session_with_track, dummy_file)["clip_id"]
+        tl_mod.add_clip(session_with_track, clip_id, 1,
+                        in_point="00:00:00.000", out_point="00:00:01.000")
+        tl_mod.remove_clip(session_with_track, 1, 0, ripple=False)
+        blank = next(item for item in tl_mod.list_clips(session_with_track, 1)
+                     if item.get("type") == "blank")
+        assert parse_time_input(blank["length"]) == timecode_to_frames("00:00:01.000") + 1
+
     def test_trim_clip(self, session_with_clip):
         result = tl_mod.trim_clip(session_with_clip, 1, 0,
                                   in_point="00:00:02.000", out_point="00:00:04.000")
@@ -457,7 +490,8 @@ class TestTimeline:
 
     def test_split_clip(self, session_with_clip):
         result = tl_mod.split_clip(session_with_clip, 1, 0, "00:00:03.000")
-        assert result["first_clip"]["out"] == "00:00:03.000"
+        expected_first_out = frames_to_timecode(timecode_to_frames("00:00:03.000") - 1)
+        assert result["first_clip"]["out"] == expected_first_out
         assert result["second_clip"]["in"] == "00:00:03.000"
         clips = [c for c in tl_mod.list_clips(session_with_clip, 1)
                  if c.get("clip_index") is not None]
@@ -520,6 +554,18 @@ class TestTimeline:
                 at_time="00:00:03.000",
             )
 
+    def test_add_clip_at_time_uses_inclusive_duration(self, session_with_track, dummy_file):
+        clip_id = media_mod.import_media(session_with_track, dummy_file)["clip_id"]
+        tl_mod.add_clip(session_with_track, clip_id, 1,
+                        in_point="00:00:00.000", out_point="00:00:01.000")
+        next_start = frames_to_timecode(timecode_to_frames("00:00:01.000") + 1)
+        tl_mod.add_clip(session_with_track, clip_id, 1,
+                        in_point="00:00:00.000", out_point="00:00:01.000",
+                        at_time=next_start)
+        items = tl_mod.list_clips(session_with_track, 1)
+        assert len([item for item in items if item.get("type") == "blank"]) == 0
+        assert len([item for item in items if item.get("clip_index") is not None]) == 2
+
     def test_add_clip_at_time_inserts_gap(self, session_with_track, dummy_file):
         clip_id = media_mod.import_media(session_with_track, dummy_file)["clip_id"]
         result = tl_mod.add_clip(
@@ -547,14 +593,16 @@ class TestTimeline:
 
     def test_add_clip_at_boundary_between_clips(self, session_with_track, dummy_file):
         clip_id = media_mod.import_media(session_with_track, dummy_file)["clip_id"]
+        next_start = frames_to_timecode(timecode_to_frames("00:00:01.000") + 1)
+        third_start = frames_to_timecode((timecode_to_frames("00:00:01.000") + 1) * 2)
         tl_mod.add_clip(session_with_track, clip_id, 1,
                         in_point="00:00:00.000", out_point="00:00:01.000")
         tl_mod.add_clip(session_with_track, clip_id, 1,
                         in_point="00:00:00.000", out_point="00:00:01.000",
-                        at_time="00:00:01.000")
+                        at_time=next_start)
         tl_mod.add_clip(session_with_track, clip_id, 1,
                         in_point="00:00:00.000", out_point="00:00:01.000",
-                        at_time="00:00:01.000")
+                        at_time=third_start)
         clips = tl_mod.list_clips(session_with_track, 1)
         real = [c for c in clips if c.get("clip_index") is not None]
         assert len(real) == 3
@@ -565,14 +613,16 @@ class TestTimeline:
 
     def test_add_clip_at_after_two_clips(self, session_with_track, dummy_file):
         clip_id = media_mod.import_media(session_with_track, dummy_file)["clip_id"]
+        next_start = frames_to_timecode(timecode_to_frames("00:00:01.000") + 1)
+        third_start = frames_to_timecode((timecode_to_frames("00:00:01.000") + 1) * 2)
         tl_mod.add_clip(session_with_track, clip_id, 1,
                         in_point="00:00:00.000", out_point="00:00:01.000")
         tl_mod.add_clip(session_with_track, clip_id, 1,
                         in_point="00:00:00.000", out_point="00:00:01.000",
-                        at_time="00:00:01.000")
+                        at_time=next_start)
         tl_mod.add_clip(session_with_track, clip_id, 1,
                         in_point="00:00:00.000", out_point="00:00:01.000",
-                        at_time="00:00:02.000")
+                        at_time=third_start)
         clips = tl_mod.list_clips(session_with_track, 1)
         real = [c for c in clips if c.get("clip_index") is not None]
         assert len(real) == 3
@@ -710,7 +760,8 @@ class TestTimeline:
                                  clip_a_index=0, duration_frames=14)
         orig_out = parse_time_input("00:00:10.000", 30000, 1001)
         result = tl_mod.split_clip(session_with_three_clips, 1, 0, "00:00:05.000")
-        assert result["first_clip"]["out"] == "00:00:05.000"
+        expected_first_out = frames_to_timecode(timecode_to_frames("00:00:05.000") - 1)
+        assert result["first_clip"]["out"] == expected_first_out
         assert abs(parse_time_input(result["second_clip"]["out"], 30000, 1001) - orig_out) <= 1
 
 
diff --git a/shotcut/agent-harness/cli_anything/shotcut/tests/test_full_e2e.py b/shotcut/agent-harness/cli_anything/shotcut/tests/test_full_e2e.py
index dc0fac969..53e4a56b8 100644
--- a/shotcut/agent-harness/cli_anything/shotcut/tests/test_full_e2e.py
+++ b/shotcut/agent-harness/cli_anything/shotcut/tests/test_full_e2e.py
@@ -8,10 +8,12 @@ CLI subprocess, and melt rendering.
 import os
 import sys
 import json
+import shutil
 import tempfile
 import subprocess
 
 import pytest
+from PIL import Image, ImageStat
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))))
 
@@ -750,6 +752,42 @@ class TestMeltRenderE2E:
             assert os.path.exists(output_path)
             assert os.path.getsize(output_path) > 0
 
+    def test_render_imported_media_is_not_black(self, session, video):
+        if shutil.which("ffmpeg") is None:
+            pytest.skip("ffmpeg is required for frame extraction")
+
+        tl_mod.add_track(session, "video", "V1")
+        clip_id = media_mod.import_media(session, video)["clip_id"]
+        tl_mod.add_clip(session, clip_id, 1, "00:00:00.000", "00:00:01.000")
+
+        with tempfile.TemporaryDirectory() as tmp_dir:
+            output_path = os.path.join(tmp_dir, "render.mp4")
+            frame_path = os.path.join(tmp_dir, "frame.png")
+
+            result = export_mod.render(session, output_path, "default", overwrite=True)
+            assert result["method"] == "melt"
+            assert os.path.exists(output_path)
+
+            subprocess.run(
+                [
+                    "ffmpeg",
+                    "-y",
+                    "-ss",
+                    "00:00:00.500",
+                    "-i",
+                    output_path,
+                    "-frames:v",
+                    "1",
+                    frame_path,
+                ],
+                check=True,
+                capture_output=True,
+                text=True,
+                timeout=120,
+            )
+            mean = ImageStat.Stat(Image.open(frame_path).convert("RGB")).mean
+            assert max(mean) > 5, f"Rendered frame appears black: {mean}"
+
 
 # ============================================================================
 # 10. CHAIN LENGTH BUG REGRESSION
diff --git a/shotcut/agent-harness/cli_anything/shotcut/utils/mlt_xml.py b/shotcut/agent-harness/cli_anything/shotcut/utils/mlt_xml.py
index 463a5e53e..0b6882e0f 100644
--- a/shotcut/agent-harness/cli_anything/shotcut/utils/mlt_xml.py
+++ b/shotcut/agent-harness/cli_anything/shotcut/utils/mlt_xml.py
@@ -58,8 +58,13 @@ def parse_mlt(filepath: str) -> ET.Element:
 
 
 def write_mlt(root: ET.Element, filepath: str) -> None:
-    """Write an MLT XML tree to a file."""
+    """Write an MLT XML tree to a file.
+
+    Normalize top-level media ordering first so playlists never
+    forward-reference chain/producer nodes declared later in the XML.
+    """
     pretty = copy.deepcopy(root)
+    normalize_top_level_order(pretty)
     ET.indent(pretty, space="  ")
     tree = ET.ElementTree(pretty)
     tree.write(filepath, xml_declaration=True, encoding="utf-8")
@@ -257,6 +262,38 @@ def create_blank_project(profile: dict) -> ET.Element:
     return root
 
 
+def _first_playlist_or_tractor_index(root: ET.Element) -> int:
+    """Return the first top-level playlist/tractor index, or len(root)."""
+    for idx, child in enumerate(list(root)):
+        if child.tag in ("playlist", "tractor"):
+            return idx
+    return len(root)
+
+
+def insert_before_playlists_and_tractors(root: ET.Element, element: ET.Element) -> None:
+    """Insert a top-level declaration before any playlists or tractors."""
+    root.insert(_first_playlist_or_tractor_index(root), element)
+    _set_parent(element, root)
+
+
+def normalize_top_level_order(root: ET.Element) -> None:
+    """Move late top-level chains/producers ahead of playlists and tractors."""
+    late_media: list[ET.Element] = []
+    seen_playlist_or_tractor = False
+    for child in list(root):
+        if child.tag in ("playlist", "tractor"):
+            seen_playlist_or_tractor = True
+        elif child.tag in ("producer", "chain") and seen_playlist_or_tractor:
+            late_media.append(child)
+
+    for element in late_media:
+        root.remove(element)
+
+    insert_idx = _first_playlist_or_tractor_index(root)
+    for offset, element in enumerate(late_media):
+        root.insert(insert_idx + offset, element)
+
+
 def _add_system_transitions(tractor: ET.Element, track_index: int,
                             root: ET.Element = None,
                             track_type: str = "video") -> None:
@@ -403,9 +440,9 @@ def create_chain(root: ET.Element, resource: str,
 
     if insert_idx is not None:
         root.insert(insert_idx, chain)
+        _set_parent(chain, root)
     else:
-        root.append(chain)
-    _set_parent(chain, root)
+        insert_before_playlists_and_tractors(root, chain)
 
     return chain
 
@@ -421,9 +458,7 @@ def create_producer(root: ET.Element, resource: str,
         "producer", prod_id, resource, in_point, out_point, caption, service
     )
 
-    insert_idx = find_insert_index_for_timeline_chain(root)
-    root.insert(insert_idx, producer)
-    _set_parent(producer, root)
+    insert_before_playlists_and_tractors(root, producer)
 
     return producer