Complete VIDEO-001 through VIDEO-004 software video studies

tests/test_video004_transport.py

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+"""Детерминированность модели и запрет позднего видеофрагмента."""
+
+from __future__ import annotations
+
+import json
+
+from protocol.video_stream_transport import FrameReassembler, FrameType, VideoFragment
+from tools.video004_transport import (
+    BASELINE_160, BASELINE_320, CODEC_RESULTS, _frames, simulate,
+)
+
+
+def test_v2_fragment_can_enter_reassembler_without_reserialization() -> None:
+    receiver = FrameReassembler(19, 1012, max_age_ms=300)
+    fragment = VideoFragment(19, 0, 0, 1, FrameType.KEYFRAME, 10, b"h264")
+    completed = receiver.offer_fragment(fragment, 10)
+    assert completed is not None and completed.data == b"h264"
+    assert receiver.offer_fragment(fragment, 11) is None
+
+
+def test_loss_model_repeats_and_zero_loss_shows_all_normal_frames() -> None:
+    codec = json.loads(CODEC_RESULTS.read_text(encoding="utf-8"))
+    baseline = json.loads(BASELINE_320.read_text(encoding="utf-8"))
+    baseline_160 = json.loads(BASELINE_160.read_text(encoding="utf-8"))
+    combined, _ = _frames("NORMAL", 640, 360, 10, baseline["windows"][0],
+                          codec, baseline_160)
+    frames = [frame for frame in combined if frame.stream_id == 0x56303334]
+    clean = simulate(frames, 10, "2/3", 8, 1, ("random", 0))
+    first = simulate(frames, 10, "2/3", 8, 2, ("random", 5))
+    second = simulate(frames, 10, "2/3", 8, 2, ("random", 5))
+    assert clean["displayed_frames"] == clean["input_frames"] == 60
+    assert first == second
+    assert first["parity_recoveries"] > 0
+    assert first["no_old_frame_replay"]