feat(#93): IMP-55 u1~u12 frontend manual section swap detection (manual_section_assignment bool axis + drag-only marker gate + dual-axis persistence + backend manual-true gate)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_user_overrides_io.py

@@ -2,9 +2,10 @@
 
 Covers the persisted axes called out in the Stage 2 plan
 (IMP-51 #79 u1 extended this to 5 axes by adding ``image_overrides``;
-IMP-45 #74 u1 extended to 6 axes by adding ``slide_css``):
+IMP-45 #74 u1 extended to 6 axes by adding ``slide_css``;
+IMP-55 #93 u1 extended to 7 axes by adding ``manual_section_assignment``):
 
-1. Round-trip ``save`` → ``load`` (6 KNOWN_AXES + foreign top-level keys).
+1. Round-trip ``save`` → ``load`` (7 KNOWN_AXES + foreign top-level keys).
 2. Unknown-key passthrough (foreign axes preserved across partial merges).
 3. Missing / corrupt / non-object behavior (graceful ``{}`` + stderr warning).
 4. Invalid keys (``InvalidOverrideKey`` raised on traversal / separators /
@@ -121,19 +122,26 @@ def _full_payload() -> dict:
             "img-1": {"x": 10.0, "y": 20.0, "w": 30.0, "h": 25.0},
         },
         "slide_css": "<style>.slide .frame-process-product .label { font-size: 14px; }</style>",
+        "manual_section_assignment": True,
     }
 
 
 def test_known_axes_includes_image_overrides():
-    """IMP-51 #79 u1 — ``image_overrides`` is a known axis (now 6 total)."""
+    """IMP-51 #79 u1 — ``image_overrides`` is a known axis (now 7 total)."""
     assert "image_overrides" in KNOWN_AXES
-    assert len(KNOWN_AXES) == 6
+    assert len(KNOWN_AXES) == 7
 
 
 def test_known_axes_includes_slide_css():
-    """IMP-45 #74 u1 — ``slide_css`` is a known axis (6 total)."""
+    """IMP-45 #74 u1 — ``slide_css`` is a known axis (7 total)."""
     assert "slide_css" in KNOWN_AXES
-    assert len(KNOWN_AXES) == 6
+    assert len(KNOWN_AXES) == 7
+
+
+def test_known_axes_includes_manual_section_assignment():
+    """IMP-55 #93 u1 — bool intent marker is a known axis (7 total)."""
+    assert "manual_section_assignment" in KNOWN_AXES
+    assert len(KNOWN_AXES) == 7
 
 
 def test_save_then_load_round_trip(tmp_path):
@@ -161,6 +169,7 @@ def test_save_partial_payload_preserves_other_axes(tmp_path):
     assert loaded["frames"] == _full_payload()["frames"]
     assert loaded["image_overrides"] == _full_payload()["image_overrides"]
     assert loaded["slide_css"] == _full_payload()["slide_css"]
+    assert loaded["manual_section_assignment"] is True
 
 
 def test_save_partial_image_overrides_preserves_other_axes(tmp_path):
@@ -183,6 +192,7 @@ def test_save_partial_image_overrides_preserves_other_axes(tmp_path):
     assert loaded["zone_sections"] == _full_payload()["zone_sections"]
     assert loaded["frames"] == _full_payload()["frames"]
     assert loaded["slide_css"] == _full_payload()["slide_css"]
+    assert loaded["manual_section_assignment"] is True
 
 
 def test_save_axis_replaces_not_deep_merges(tmp_path):
@@ -226,6 +236,24 @@ def test_save_preserves_foreign_top_level_keys(tmp_path):
     assert loaded["schema_version"] == pre_seed["schema_version"]
 
 
+def test_save_manual_section_assignment_round_trips_both_booleans(tmp_path):
+    """IMP-55 #93 u1 — bool axis round-trips true/false and clears on None.
+
+    Asserts the bool is preserved literally (not coerced to int / string) so
+    the backend pipeline (u9) can branch on ``is True`` without false-positive
+    matches from truthy-but-not-True values seeded by older callers.
+    """
+    key = "03"
+    save(key, {"manual_section_assignment": True}, root=tmp_path)
+    assert load(key, root=tmp_path)["manual_section_assignment"] is True
+
+    save(key, {"manual_section_assignment": False}, root=tmp_path)
+    assert load(key, root=tmp_path)["manual_section_assignment"] is False
+
+    save(key, {"manual_section_assignment": None}, root=tmp_path)
+    assert "manual_section_assignment" not in load(key, root=tmp_path)
+
+
 def test_save_creates_parent_directory(tmp_path):
     nested = tmp_path / "deep" / "nest"
     assert not nested.exists()
@@ -241,6 +269,7 @@ def test_save_writes_pretty_sorted_json_for_diffability(tmp_path):
     pos_frames = raw.index('"frames"')
     pos_image_overrides = raw.index('"image_overrides"')
     pos_layout = raw.index('"layout"')
+    pos_manual = raw.index('"manual_section_assignment"')
     pos_slide_css = raw.index('"slide_css"')
     pos_zg = raw.index('"zone_geometries"')
     pos_zs = raw.index('"zone_sections"')
@@ -248,6 +277,7 @@ def test_save_writes_pretty_sorted_json_for_diffability(tmp_path):
         pos_frames
         < pos_image_overrides
         < pos_layout
+        < pos_manual
         < pos_slide_css
         < pos_zg
         < pos_zs