fix(variation_checker): measure longest run for consecutive same-size shots

Check 2 flagged 'N consecutive same-size shots' from a count of every equal
adjacent pair across the whole plan, not the length of any real run. So three
separate 2-shot groups (wide,wide,cu,cu,med,med) tripped a false '3
consecutive' violation, while a genuine run of 3 (only 2 pairs) was never
flagged. Track the current run length, reset on change, and compare the longest
run >= 3.

Adds regression tests: non-consecutive pairs pass, a true run of 3 is flagged,
unspecified shots don't form a run.

Closes #268

lib/variation_checker.py

@@ -56,13 +56,20 @@ def check_scene_variation(scenes: list[dict[str, Any]]) -> dict[str, Any]:
             suggestions.append("Mix wide establishing shots with close-ups for visual rhythm.")
 
     # --- Check 2: Consecutive same-size shots ---
-    consecutive_same = 0
+    # Track the longest actual run of identical shot sizes. Summing every equal
+    # adjacent pair across the whole plan would count non-consecutive groups
+    # (e.g. wide,wide,cu,cu,med,med -> 3 pairs) as a single "3 consecutive" run.
+    longest_run = 1 if shot_sizes else 0
+    current_run = 1
     for i in range(1, len(shot_sizes)):
         if shot_sizes[i] == shot_sizes[i-1] and shot_sizes[i] != "unspecified":
-            consecutive_same += 1
-    if consecutive_same >= 3:
+            current_run += 1
+            longest_run = max(longest_run, current_run)
+        else:
+            current_run = 1
+    if longest_run >= 3:
         violations.append(
-            f"{consecutive_same} consecutive same-size shots. "
+            f"{longest_run} consecutive same-size shots. "
             f"Vary shot sizes between scenes for editorial rhythm."
         )
 

tests/lib/test_variation_checker_runs.py

@@ -0,0 +1,37 @@
+"""Regression test for check_scene_variation consecutive-run counting.
+
+The "consecutive same-size shots" check summed every equal adjacent pair across
+the whole plan instead of measuring the longest actual run, so an editorially
+varied plan of separate 2-shot groups (wide,wide,cu,cu,med,med) falsely tripped
+a "3 consecutive same-size shots" violation.
+"""
+
+import sys
+from pathlib import Path
+
+PROJECT_ROOT = Path(__file__).resolve().parent.parent.parent
+sys.path.insert(0, str(PROJECT_ROOT))
+
+from lib.variation_checker import check_scene_variation  # noqa: E402
+
+
+def _scenes(sizes):
+    return [{"shot_language": {"shot_size": s}} for s in sizes]
+
+
+def test_non_consecutive_same_size_pairs_do_not_trip_run_check():
+    # Three separate 2-shot groups — longest run is 2, not 3.
+    res = check_scene_variation(_scenes(["wide", "wide", "cu", "cu", "medium", "medium"]))
+    assert not any("consecutive same-size" in v for v in res["violations"])
+
+
+def test_true_run_of_three_is_flagged():
+    res = check_scene_variation(_scenes(["wide", "wide", "wide", "cu", "medium"]))
+    assert any("3 consecutive same-size" in v for v in res["violations"])
+
+
+def test_unspecified_shots_do_not_form_a_run():
+    res = check_scene_variation(
+        _scenes(["unspecified", "unspecified", "unspecified", "unspecified"])
+    )
+    assert not any("consecutive same-size" in v for v in res["violations"])