diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4d37c01bb..419c71765 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,10 @@
+- 2026-08-25: Continued #2564 test-module refactoring by moving the contiguous
+  stable-selection GRIDV report/label regression family from
+  `test_studio_host_json_settings_page_layout_fields.cpp` into
+  `test_studio_host_json_settings_page_layout_grid_vertical_fields.inl`. The
+  aggregate test target, invocation order, Studio host JSON, report/label,
+  localization, and machine contracts are unchanged.
+
 - 2026-08-25: Continued #2564 test-module refactoring by moving the contiguous
   CDX/DCX/IDX/NDX/MDX index-probe and localized-diagnostic regressions from
   `test_vfp_assets.cpp` into `test_vfp_assets_index_probe_contracts.inl`. The
diff --git a/agent-handoff.md b/agent-handoff.md
index 839023f27..84755dfb8 100644
--- a/agent-handoff.md
+++ b/agent-handoff.md
@@ -1,5 +1,16 @@
 # Agent Handoff
 
+## V1 Studio GRIDV regression module
+
+The bounded #5230/#2564 structural slice moves the contiguous stable-selection
+GRIDV report/label regression family from
+`test_studio_host_json_settings_page_layout_fields.cpp` to
+`test_studio_host_json_settings_page_layout_grid_vertical_fields.inl`. The
+fragment remains in the same test translation-unit namespace; the aggregate
+executable, existing declarations, invocation order, fixtures, Studio host
+JSON, report/label, localization, and machine contracts remain unchanged. A
+focused native rerun is required before merge.
+
 ## V1 index-probe asset test module
 
 The bounded #5226/#2564 structural slice moves the contiguous CDX/DCX/IDX/NDX/
diff --git a/tests/test_studio_host_json_settings_page_layout_fields.cpp b/tests/test_studio_host_json_settings_page_layout_fields.cpp
index 676906991..8c1bc172a 100644
--- a/tests/test_studio_host_json_settings_page_layout_fields.cpp
+++ b/tests/test_studio_host_json_settings_page_layout_fields.cpp
@@ -1200,390 +1200,7 @@ void test_studio_host_json_clears_deleted_report_right_margin_fields_by_stable_s
     }
 }
 
-void test_studio_host_json_updates_report_grid_vertical_fields_by_stable_selection(
-    const std::string& studio_host_path) {
-    namespace fs = std::filesystem;
-
-    const fs::path temp_root =
-        fs::temp_directory_path() / "copperfin_studio_host_report_grid_vertical_field_stable_json_tests";
-    std::error_code ignored;
-    fs::remove_all(temp_root, ignored);
-    fs::create_directories(temp_root);
-
-    const auto run_grid_vertical_update = [&](const fs::path& asset_path,
-                                              const std::string& title,
-                                              const std::string& updated_grid,
-                                              const std::string& label) {
-        write_synthetic_report_table_for_stable_grid_vertical_field_json(asset_path);
-        const auto update_process = run_process_capture(
-            studio_host_path,
-            {
-                "--path", asset_path.string(),
-                "--set-property",
-                "--unique-id", "settings-guid",
-                "--property-name", "GRIDV",
-                "--property-value", updated_grid,
-                "--json"
-            },
-            temp_root);
-
-        if (update_process.exit_code != 0) {
-            std::cerr << "studio host " << label << " stable vertical-grid field update stdout:\n"
-                      << update_process.stdout_text << "\n";
-            std::cerr << "studio host " << label << " stable vertical-grid field update stderr:\n"
-                      << update_process.stderr_text << "\n";
-            std::cerr << "fixture root: " << temp_root << "\n";
-        }
-
-        expect(update_process.exit_code == 0,
-               "#1831: report/label stable vertical-grid field update should exit successfully");
-        const auto grid_property = copperfin::vfp::query_visual_object_property({
-            .path = asset_path.string(),
-            .record_index = 0U,
-            .object_name = {},
-            .unique_id = "settings-guid",
-            .property_name = "GRIDV"
-        });
-        expect(grid_property.ok && grid_property.exists && grid_property.value == updated_grid,
-               "#1831: report/label stable vertical-grid field update should persist the GRIDV field");
-        expect_contains(update_process.stdout_text, "\"documentTitle\": \"" + title + "\"",
-                        "#1831: report/label stable vertical-grid field update should return refreshed report-layout JSON");
-        if (asset_path.extension() == ".lbx") {
-            expect_contains(update_process.stdout_text, "\"isLabel\": true",
-                            "#1831: label stable vertical-grid field update should retain label identity");
-        }
-        expect_empty_report_layout_preview_bounds(
-            update_process.stdout_text,
-            "#2025: stable-selected report/label vertical-grid update JSON");
-        expect_contains(update_process.stdout_text, "\"pageSetupAvailable\": true",
-                        "#1831: report/label stable vertical-grid field update should preserve page setup availability");
-        expect_contains(update_process.stdout_text, "\"topMargin\": 10",
-                        "#1831: report/label stable vertical-grid field update should preserve memo-derived top margins");
-        expect_contains(update_process.stdout_text, "\"bottomMargin\": 20",
-                        "#1831: report/label stable vertical-grid field update should preserve memo-derived bottom margins");
-        expect_contains(update_process.stdout_text, "\"gridVertical\": " + updated_grid,
-                        "#1831: report/label stable vertical-grid field update should refresh vertical grid spacing");
-        expect_contains(update_process.stdout_text, "\"gridHorizontal\": 8",
-                        "#1831: report/label stable vertical-grid field update should preserve horizontal grid spacing");
-        expect_contains(update_process.stdout_text, "\"settingCount\": 4",
-                        "#1831: report/label stable vertical-grid field update should preserve setting counts");
-        expect_contains(update_process.stdout_text, "\"selectedReportSettingsAvailable\": true",
-                        "#1831: report/label stable vertical-grid field update should preserve selected-settings availability");
-        expect_contains(update_process.stdout_text, "\"selectedReportSelectionKind\": \"settings\"",
-                        "#1831: report/label stable vertical-grid field update should preserve settings selection kind");
-        expect_contains_in_order(
-            update_process.stdout_text,
-            {
-                "\"selectedReportSettings\": [",
-                "\"name\": \"TOPMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 0",
-                "\"name\": \"BOTMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 1",
-                "\"name\": \"GRIDH\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 2",
-                "\"name\": \"GRIDV\", \"recordIndex\": 0, \"fieldIndex\": 3, \"sourceLineIndex\": null",
-                "\"value\": \"" + updated_grid + "\""
-            },
-            "#1831: report/label stable vertical-grid field update should refresh selected direct-field provenance");
-    };
-
-    run_grid_vertical_update(temp_root / "grid_vertical_stable.frx",
-                             "grid_vertical_stable.frx",
-                             "12",
-                             "report");
-    run_grid_vertical_update(temp_root / "grid_vertical_stable.lbx",
-                             "grid_vertical_stable.lbx",
-                             "14",
-                             "label");
-
-    if (failures == 0) {
-        fs::remove_all(temp_root, ignored);
-    }
-}
-
-void test_studio_host_json_clears_report_grid_vertical_fields_by_stable_selection(
-    const std::string& studio_host_path) {
-    namespace fs = std::filesystem;
-
-    const fs::path temp_root =
-        fs::temp_directory_path() / "copperfin_studio_host_report_grid_vertical_clear_stable_json_tests";
-    std::error_code ignored;
-    fs::remove_all(temp_root, ignored);
-    fs::create_directories(temp_root);
-
-    const auto run_grid_vertical_clear = [&](const fs::path& asset_path,
-                                             const std::string& title,
-                                             const std::string& label) {
-        write_synthetic_report_table_for_stable_grid_vertical_field_json(asset_path);
-        const auto clear_process = run_process_capture(
-            studio_host_path,
-            {
-                "--path", asset_path.string(),
-                "--clear-property",
-                "--unique-id", "settings-guid",
-                "--property-name", "GRIDV",
-                "--json"
-            },
-            temp_root);
-
-        if (clear_process.exit_code != 0) {
-            std::cerr << "studio host " << label << " stable vertical-grid field clear stdout:\n"
-                      << clear_process.stdout_text << "\n";
-            std::cerr << "studio host " << label << " stable vertical-grid field clear stderr:\n"
-                      << clear_process.stderr_text << "\n";
-            std::cerr << "fixture root: " << temp_root << "\n";
-        }
-
-        expect(clear_process.exit_code == 0,
-               "#1831: report/label stable vertical-grid field clear should exit successfully");
-        const auto grid_property = copperfin::vfp::query_visual_object_property({
-            .path = asset_path.string(),
-            .record_index = 0U,
-            .object_name = {},
-            .unique_id = "settings-guid",
-            .property_name = "GRIDV"
-        });
-        expect(grid_property.ok && grid_property.exists && grid_property.value.empty(),
-               "#1831: report/label stable vertical-grid field clear should blank the GRIDV field");
-        expect_contains(clear_process.stdout_text, "\"documentTitle\": \"" + title + "\"",
-                        "#1831: report/label stable vertical-grid field clear should return refreshed report-layout JSON");
-        if (asset_path.extension() == ".lbx") {
-            expect_contains(clear_process.stdout_text, "\"isLabel\": true",
-                            "#1831: label stable vertical-grid field clear should retain label identity");
-        }
-        expect_empty_report_layout_preview_bounds(
-            clear_process.stdout_text,
-            "#2025: stable-selected report/label vertical-grid clear JSON");
-        expect_contains(clear_process.stdout_text, "\"pageSetupAvailable\": true",
-                        "#1831: report/label stable vertical-grid field clear should preserve page setup availability");
-        expect_contains(clear_process.stdout_text, "\"topMargin\": 10",
-                        "#1831: report/label stable vertical-grid field clear should preserve memo-derived top margins");
-        expect_contains(clear_process.stdout_text, "\"bottomMargin\": 20",
-                        "#1831: report/label stable vertical-grid field clear should preserve memo-derived bottom margins");
-        expect_contains(clear_process.stdout_text, "\"gridVerticalAvailable\": false",
-                        "#1831: report/label stable vertical-grid field clear should clear vertical-grid availability");
-        expect_contains(clear_process.stdout_text, "\"gridVertical\": 0",
-                        "#1831: report/label stable vertical-grid field clear should clear vertical grid spacing");
-        expect_contains(clear_process.stdout_text, "\"gridHorizontal\": 8",
-                        "#1831: report/label stable vertical-grid field clear should preserve horizontal grid spacing");
-        expect_contains(clear_process.stdout_text, "\"settingCount\": 3",
-                        "#1831: report/label stable vertical-grid field clear should remove the direct setting from counts");
-        expect_contains(clear_process.stdout_text, "\"selectedReportSettingsAvailable\": true",
-                        "#1831: report/label stable vertical-grid field clear should preserve selected-settings availability");
-        expect_contains(clear_process.stdout_text, "\"selectedReportSelectionKind\": \"settings\"",
-                        "#1831: report/label stable vertical-grid field clear should preserve settings selection kind");
-        expect_contains_in_order(
-            clear_process.stdout_text,
-            {
-                "\"selectedReportSettings\": [",
-                "\"name\": \"TOPMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 0",
-                "\"name\": \"BOTMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 1",
-                "\"name\": \"GRIDH\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 2"
-            },
-            "#1831: report/label stable vertical-grid field clear should preserve remaining selected setting provenance");
-        expect_not_contains(clear_process.stdout_text,
-                            "\"name\": \"GRIDV\", \"recordIndex\": 0, \"fieldIndex\": 3",
-                            "#1831: report/label stable vertical-grid field clear should remove direct GRIDV provenance");
-    };
-
-    run_grid_vertical_clear(temp_root / "grid_vertical_clear_stable.frx",
-                            "grid_vertical_clear_stable.frx",
-                            "report");
-    run_grid_vertical_clear(temp_root / "grid_vertical_clear_stable.lbx",
-                            "grid_vertical_clear_stable.lbx",
-                            "label");
-
-    if (failures == 0) {
-        fs::remove_all(temp_root, ignored);
-    }
-}
-
-void test_studio_host_json_updates_deleted_report_grid_vertical_fields_by_stable_selection(
-    const std::string& studio_host_path) {
-    namespace fs = std::filesystem;
-
-    const fs::path temp_root =
-        fs::temp_directory_path() / "copperfin_studio_host_deleted_report_grid_vertical_field_stable_json_tests";
-    std::error_code ignored;
-    fs::remove_all(temp_root, ignored);
-    fs::create_directories(temp_root);
-
-    const auto run_deleted_grid_vertical_update = [&](const fs::path& asset_path,
-                                                      const std::string& title,
-                                                      const std::string& updated_grid,
-                                                      const std::string& label) {
-        write_synthetic_report_table_for_stable_deleted_grid_vertical_field_json(asset_path);
-        const auto update_process = run_process_capture(
-            studio_host_path,
-            {
-                "--path", asset_path.string(),
-                "--set-property",
-                "--unique-id", "deleted-settings-guid",
-                "--property-name", "GRIDV",
-                "--property-value", updated_grid,
-                "--json"
-            },
-            temp_root);
-
-        if (update_process.exit_code != 0) {
-            std::cerr << "studio host " << label << " stable deleted vertical-grid field update stdout:\n"
-                      << update_process.stdout_text << "\n";
-            std::cerr << "studio host " << label << " stable deleted vertical-grid field update stderr:\n"
-                      << update_process.stderr_text << "\n";
-            std::cerr << "fixture root: " << temp_root << "\n";
-        }
-
-        expect(update_process.exit_code == 0,
-               "#1831: report/label stable deleted vertical-grid field update should exit successfully");
-        const auto grid_property = copperfin::vfp::query_visual_object_property({
-            .path = asset_path.string(),
-            .record_index = 0U,
-            .object_name = {},
-            .unique_id = "deleted-settings-guid",
-            .property_name = "GRIDV"
-        });
-        expect(grid_property.ok && grid_property.exists && grid_property.value == updated_grid,
-               "#1831: report/label stable deleted vertical-grid field update should persist the GRIDV field");
-        expect_contains(update_process.stdout_text, "\"documentTitle\": \"" + title + "\"",
-                        "#1831: report/label stable deleted vertical-grid field update should return refreshed report-layout JSON");
-        if (asset_path.extension() == ".lbx") {
-            expect_contains(update_process.stdout_text, "\"isLabel\": true",
-                            "#1831: label stable deleted vertical-grid field update should retain label identity");
-        }
-        expect_empty_report_layout_preview_bounds(
-            update_process.stdout_text,
-            "#2025: stable-selected deleted report/label vertical-grid update JSON");
-        expect_contains(update_process.stdout_text, "\"pageSetupAvailable\": true",
-                        "#3815: report/label stable deleted vertical-grid field update should expose effective page setup");
-        expect_contains(update_process.stdout_text, "\"gridVerticalAvailable\": true",
-                        "#3815: report/label stable deleted vertical-grid field update should expose effective availability");
-        expect_contains(update_process.stdout_text, "\"gridVertical\": " + updated_grid,
-                        "#3815: report/label stable deleted vertical-grid field update should expose the effective value");
-        expect_contains(update_process.stdout_text, "\"settingCount\": 0",
-                        "#1831: report/label stable deleted vertical-grid field update should not fabricate live settings");
-        expect_contains(update_process.stdout_text, "\"deletedSettingCount\": 4",
-                        "#1831: report/label stable deleted vertical-grid field update should preserve deleted setting counts");
-        expect_contains(update_process.stdout_text, "\"selectedReportSettingsAvailable\": true",
-                        "#1831: report/label stable deleted vertical-grid field update should preserve selected-settings availability");
-        expect_contains(update_process.stdout_text, "\"selectedReportSelectionKind\": \"settings\"",
-                        "#1831: report/label stable deleted vertical-grid field update should preserve settings selection kind");
-        expect_contains_in_order(
-            update_process.stdout_text,
-            {
-                "\"selectedReportSettings\": [",
-                "\"name\": \"TOPMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 0",
-                "\"name\": \"BOTMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 1",
-                "\"name\": \"GRIDH\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 2",
-                "\"name\": \"GRIDV\", \"recordIndex\": 0, \"fieldIndex\": 3, \"sourceLineIndex\": null",
-                "\"value\": \"" + updated_grid + "\""
-            },
-            "#1831: report/label stable deleted vertical-grid field update should refresh selected deleted settings");
-    };
-
-    run_deleted_grid_vertical_update(temp_root / "deleted_grid_vertical_stable.frx",
-                                     "deleted_grid_vertical_stable.frx",
-                                     "12",
-                                     "report");
-    run_deleted_grid_vertical_update(temp_root / "deleted_grid_vertical_stable.lbx",
-                                     "deleted_grid_vertical_stable.lbx",
-                                     "14",
-                                     "label");
-
-    if (failures == 0) {
-        fs::remove_all(temp_root, ignored);
-    }
-}
-
-void test_studio_host_json_clears_deleted_report_grid_vertical_fields_by_stable_selection(
-    const std::string& studio_host_path) {
-    namespace fs = std::filesystem;
-
-    const fs::path temp_root =
-        fs::temp_directory_path() / "copperfin_studio_host_deleted_report_grid_vertical_clear_stable_json_tests";
-    std::error_code ignored;
-    fs::remove_all(temp_root, ignored);
-    fs::create_directories(temp_root);
-
-    const auto run_deleted_grid_vertical_clear = [&](const fs::path& asset_path,
-                                                     const std::string& title,
-                                                     const std::string& label) {
-        write_synthetic_report_table_for_stable_deleted_grid_vertical_field_json(asset_path);
-        const auto clear_process = run_process_capture(
-            studio_host_path,
-            {
-                "--path", asset_path.string(),
-                "--clear-property",
-                "--unique-id", "deleted-settings-guid",
-                "--property-name", "GRIDV",
-                "--json"
-            },
-            temp_root);
-
-        if (clear_process.exit_code != 0) {
-            std::cerr << "studio host " << label << " stable deleted vertical-grid field clear stdout:\n"
-                      << clear_process.stdout_text << "\n";
-            std::cerr << "studio host " << label << " stable deleted vertical-grid field clear stderr:\n"
-                      << clear_process.stderr_text << "\n";
-            std::cerr << "fixture root: " << temp_root << "\n";
-        }
-
-        expect(clear_process.exit_code == 0,
-               "#1831: report/label stable deleted vertical-grid field clear should exit successfully");
-        const auto grid_property = copperfin::vfp::query_visual_object_property({
-            .path = asset_path.string(),
-            .record_index = 0U,
-            .object_name = {},
-            .unique_id = "deleted-settings-guid",
-            .property_name = "GRIDV"
-        });
-        expect(grid_property.ok && grid_property.exists && grid_property.value.empty(),
-               "#1831: report/label stable deleted vertical-grid field clear should blank the GRIDV field");
-        expect_contains(clear_process.stdout_text, "\"documentTitle\": \"" + title + "\"",
-                        "#1831: report/label stable deleted vertical-grid field clear should return refreshed report-layout JSON");
-        if (asset_path.extension() == ".lbx") {
-            expect_contains(clear_process.stdout_text, "\"isLabel\": true",
-                            "#1831: label stable deleted vertical-grid field clear should retain label identity");
-        }
-        expect_empty_report_layout_preview_bounds(
-            clear_process.stdout_text,
-            "#2025: stable-selected deleted report/label vertical-grid clear JSON");
-        expect_contains(clear_process.stdout_text, "\"pageSetupAvailable\": true",
-                        "#3815: report/label stable deleted vertical-grid field clear should preserve effective page setup");
-        expect_contains(clear_process.stdout_text, "\"gridVerticalAvailable\": false",
-                        "#3815: report/label stable deleted vertical-grid field clear should clear effective availability");
-        expect_contains(clear_process.stdout_text, "\"gridVertical\": 0",
-                        "#3815: report/label stable deleted vertical-grid field clear should reset the effective value");
-        expect_contains(clear_process.stdout_text, "\"settingCount\": 0",
-                        "#1831: report/label stable deleted vertical-grid field clear should not fabricate live settings");
-        expect_contains(clear_process.stdout_text, "\"deletedSettingCount\": 3",
-                        "#1831: report/label stable deleted vertical-grid field clear should remove the deleted direct setting from counts");
-        expect_contains(clear_process.stdout_text, "\"selectedReportSettingsAvailable\": true",
-                        "#1831: report/label stable deleted vertical-grid field clear should preserve selected-settings availability");
-        expect_contains(clear_process.stdout_text, "\"selectedReportSelectionKind\": \"settings\"",
-                        "#1831: report/label stable deleted vertical-grid field clear should preserve settings selection kind");
-        expect_contains_in_order(
-            clear_process.stdout_text,
-            {
-                "\"selectedReportSettings\": [",
-                "\"name\": \"TOPMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 0",
-                "\"name\": \"BOTMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 1",
-                "\"name\": \"GRIDH\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 2"
-            },
-            "#1831: report/label stable deleted vertical-grid field clear should preserve remaining selected deleted settings");
-        expect_not_contains(clear_process.stdout_text,
-                            "\"name\": \"GRIDV\", \"recordIndex\": 0, \"fieldIndex\": 3",
-                            "#1831: report/label stable deleted vertical-grid field clear should remove direct GRIDV provenance");
-    };
-
-    run_deleted_grid_vertical_clear(temp_root / "deleted_grid_vertical_clear_stable.frx",
-                                    "deleted_grid_vertical_clear_stable.frx",
-                                    "report");
-    run_deleted_grid_vertical_clear(temp_root / "deleted_grid_vertical_clear_stable.lbx",
-                                    "deleted_grid_vertical_clear_stable.lbx",
-                                    "label");
-
-    if (failures == 0) {
-        fs::remove_all(temp_root, ignored);
-    }
-}
-
+#include "test_studio_host_json_settings_page_layout_grid_vertical_fields.inl"
 void test_studio_host_json_updates_report_grid_horizontal_fields_by_stable_selection(
     const std::string& studio_host_path) {
     namespace fs = std::filesystem;
diff --git a/tests/test_studio_host_json_settings_page_layout_grid_vertical_fields.inl b/tests/test_studio_host_json_settings_page_layout_grid_vertical_fields.inl
new file mode 100644
index 000000000..8fa180eb6
--- /dev/null
+++ b/tests/test_studio_host_json_settings_page_layout_grid_vertical_fields.inl
@@ -0,0 +1,382 @@
+void test_studio_host_json_updates_report_grid_vertical_fields_by_stable_selection(
+    const std::string& studio_host_path) {
+    namespace fs = std::filesystem;
+
+    const fs::path temp_root =
+        fs::temp_directory_path() / "copperfin_studio_host_report_grid_vertical_field_stable_json_tests";
+    std::error_code ignored;
+    fs::remove_all(temp_root, ignored);
+    fs::create_directories(temp_root);
+
+    const auto run_grid_vertical_update = [&](const fs::path& asset_path,
+                                              const std::string& title,
+                                              const std::string& updated_grid,
+                                              const std::string& label) {
+        write_synthetic_report_table_for_stable_grid_vertical_field_json(asset_path);
+        const auto update_process = run_process_capture(
+            studio_host_path,
+            {
+                "--path", asset_path.string(),
+                "--set-property",
+                "--unique-id", "settings-guid",
+                "--property-name", "GRIDV",
+                "--property-value", updated_grid,
+                "--json"
+            },
+            temp_root);
+
+        if (update_process.exit_code != 0) {
+            std::cerr << "studio host " << label << " stable vertical-grid field update stdout:\n"
+                      << update_process.stdout_text << "\n";
+            std::cerr << "studio host " << label << " stable vertical-grid field update stderr:\n"
+                      << update_process.stderr_text << "\n";
+            std::cerr << "fixture root: " << temp_root << "\n";
+        }
+
+        expect(update_process.exit_code == 0,
+               "#1831: report/label stable vertical-grid field update should exit successfully");
+        const auto grid_property = copperfin::vfp::query_visual_object_property({
+            .path = asset_path.string(),
+            .record_index = 0U,
+            .object_name = {},
+            .unique_id = "settings-guid",
+            .property_name = "GRIDV"
+        });
+        expect(grid_property.ok && grid_property.exists && grid_property.value == updated_grid,
+               "#1831: report/label stable vertical-grid field update should persist the GRIDV field");
+        expect_contains(update_process.stdout_text, "\"documentTitle\": \"" + title + "\"",
+                        "#1831: report/label stable vertical-grid field update should return refreshed report-layout JSON");
+        if (asset_path.extension() == ".lbx") {
+            expect_contains(update_process.stdout_text, "\"isLabel\": true",
+                            "#1831: label stable vertical-grid field update should retain label identity");
+        }
+        expect_empty_report_layout_preview_bounds(
+            update_process.stdout_text,
+            "#2025: stable-selected report/label vertical-grid update JSON");
+        expect_contains(update_process.stdout_text, "\"pageSetupAvailable\": true",
+                        "#1831: report/label stable vertical-grid field update should preserve page setup availability");
+        expect_contains(update_process.stdout_text, "\"topMargin\": 10",
+                        "#1831: report/label stable vertical-grid field update should preserve memo-derived top margins");
+        expect_contains(update_process.stdout_text, "\"bottomMargin\": 20",
+                        "#1831: report/label stable vertical-grid field update should preserve memo-derived bottom margins");
+        expect_contains(update_process.stdout_text, "\"gridVertical\": " + updated_grid,
+                        "#1831: report/label stable vertical-grid field update should refresh vertical grid spacing");
+        expect_contains(update_process.stdout_text, "\"gridHorizontal\": 8",
+                        "#1831: report/label stable vertical-grid field update should preserve horizontal grid spacing");
+        expect_contains(update_process.stdout_text, "\"settingCount\": 4",
+                        "#1831: report/label stable vertical-grid field update should preserve setting counts");
+        expect_contains(update_process.stdout_text, "\"selectedReportSettingsAvailable\": true",
+                        "#1831: report/label stable vertical-grid field update should preserve selected-settings availability");
+        expect_contains(update_process.stdout_text, "\"selectedReportSelectionKind\": \"settings\"",
+                        "#1831: report/label stable vertical-grid field update should preserve settings selection kind");
+        expect_contains_in_order(
+            update_process.stdout_text,
+            {
+                "\"selectedReportSettings\": [",
+                "\"name\": \"TOPMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 0",
+                "\"name\": \"BOTMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 1",
+                "\"name\": \"GRIDH\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 2",
+                "\"name\": \"GRIDV\", \"recordIndex\": 0, \"fieldIndex\": 3, \"sourceLineIndex\": null",
+                "\"value\": \"" + updated_grid + "\""
+            },
+            "#1831: report/label stable vertical-grid field update should refresh selected direct-field provenance");
+    };
+
+    run_grid_vertical_update(temp_root / "grid_vertical_stable.frx",
+                             "grid_vertical_stable.frx",
+                             "12",
+                             "report");
+    run_grid_vertical_update(temp_root / "grid_vertical_stable.lbx",
+                             "grid_vertical_stable.lbx",
+                             "14",
+                             "label");
+
+    if (failures == 0) {
+        fs::remove_all(temp_root, ignored);
+    }
+}
+void test_studio_host_json_clears_report_grid_vertical_fields_by_stable_selection(
+    const std::string& studio_host_path) {
+    namespace fs = std::filesystem;
+
+    const fs::path temp_root =
+        fs::temp_directory_path() / "copperfin_studio_host_report_grid_vertical_clear_stable_json_tests";
+    std::error_code ignored;
+    fs::remove_all(temp_root, ignored);
+    fs::create_directories(temp_root);
+
+    const auto run_grid_vertical_clear = [&](const fs::path& asset_path,
+                                             const std::string& title,
+                                             const std::string& label) {
+        write_synthetic_report_table_for_stable_grid_vertical_field_json(asset_path);
+        const auto clear_process = run_process_capture(
+            studio_host_path,
+            {
+                "--path", asset_path.string(),
+                "--clear-property",
+                "--unique-id", "settings-guid",
+                "--property-name", "GRIDV",
+                "--json"
+            },
+            temp_root);
+
+        if (clear_process.exit_code != 0) {
+            std::cerr << "studio host " << label << " stable vertical-grid field clear stdout:\n"
+                      << clear_process.stdout_text << "\n";
+            std::cerr << "studio host " << label << " stable vertical-grid field clear stderr:\n"
+                      << clear_process.stderr_text << "\n";
+            std::cerr << "fixture root: " << temp_root << "\n";
+        }
+
+        expect(clear_process.exit_code == 0,
+               "#1831: report/label stable vertical-grid field clear should exit successfully");
+        const auto grid_property = copperfin::vfp::query_visual_object_property({
+            .path = asset_path.string(),
+            .record_index = 0U,
+            .object_name = {},
+            .unique_id = "settings-guid",
+            .property_name = "GRIDV"
+        });
+        expect(grid_property.ok && grid_property.exists && grid_property.value.empty(),
+               "#1831: report/label stable vertical-grid field clear should blank the GRIDV field");
+        expect_contains(clear_process.stdout_text, "\"documentTitle\": \"" + title + "\"",
+                        "#1831: report/label stable vertical-grid field clear should return refreshed report-layout JSON");
+        if (asset_path.extension() == ".lbx") {
+            expect_contains(clear_process.stdout_text, "\"isLabel\": true",
+                            "#1831: label stable vertical-grid field clear should retain label identity");
+        }
+        expect_empty_report_layout_preview_bounds(
+            clear_process.stdout_text,
+            "#2025: stable-selected report/label vertical-grid clear JSON");
+        expect_contains(clear_process.stdout_text, "\"pageSetupAvailable\": true",
+                        "#1831: report/label stable vertical-grid field clear should preserve page setup availability");
+        expect_contains(clear_process.stdout_text, "\"topMargin\": 10",
+                        "#1831: report/label stable vertical-grid field clear should preserve memo-derived top margins");
+        expect_contains(clear_process.stdout_text, "\"bottomMargin\": 20",
+                        "#1831: report/label stable vertical-grid field clear should preserve memo-derived bottom margins");
+        expect_contains(clear_process.stdout_text, "\"gridVerticalAvailable\": false",
+                        "#1831: report/label stable vertical-grid field clear should clear vertical-grid availability");
+        expect_contains(clear_process.stdout_text, "\"gridVertical\": 0",
+                        "#1831: report/label stable vertical-grid field clear should clear vertical grid spacing");
+        expect_contains(clear_process.stdout_text, "\"gridHorizontal\": 8",
+                        "#1831: report/label stable vertical-grid field clear should preserve horizontal grid spacing");
+        expect_contains(clear_process.stdout_text, "\"settingCount\": 3",
+                        "#1831: report/label stable vertical-grid field clear should remove the direct setting from counts");
+        expect_contains(clear_process.stdout_text, "\"selectedReportSettingsAvailable\": true",
+                        "#1831: report/label stable vertical-grid field clear should preserve selected-settings availability");
+        expect_contains(clear_process.stdout_text, "\"selectedReportSelectionKind\": \"settings\"",
+                        "#1831: report/label stable vertical-grid field clear should preserve settings selection kind");
+        expect_contains_in_order(
+            clear_process.stdout_text,
+            {
+                "\"selectedReportSettings\": [",
+                "\"name\": \"TOPMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 0",
+                "\"name\": \"BOTMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 1",
+                "\"name\": \"GRIDH\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 2"
+            },
+            "#1831: report/label stable vertical-grid field clear should preserve remaining selected setting provenance");
+        expect_not_contains(clear_process.stdout_text,
+                            "\"name\": \"GRIDV\", \"recordIndex\": 0, \"fieldIndex\": 3",
+                            "#1831: report/label stable vertical-grid field clear should remove direct GRIDV provenance");
+    };
+
+    run_grid_vertical_clear(temp_root / "grid_vertical_clear_stable.frx",
+                            "grid_vertical_clear_stable.frx",
+                            "report");
+    run_grid_vertical_clear(temp_root / "grid_vertical_clear_stable.lbx",
+                            "grid_vertical_clear_stable.lbx",
+                            "label");
+
+    if (failures == 0) {
+        fs::remove_all(temp_root, ignored);
+    }
+}
+
+void test_studio_host_json_updates_deleted_report_grid_vertical_fields_by_stable_selection(
+    const std::string& studio_host_path) {
+    namespace fs = std::filesystem;
+
+    const fs::path temp_root =
+        fs::temp_directory_path() / "copperfin_studio_host_deleted_report_grid_vertical_field_stable_json_tests";
+    std::error_code ignored;
+    fs::remove_all(temp_root, ignored);
+    fs::create_directories(temp_root);
+
+    const auto run_deleted_grid_vertical_update = [&](const fs::path& asset_path,
+                                                      const std::string& title,
+                                                      const std::string& updated_grid,
+                                                      const std::string& label) {
+        write_synthetic_report_table_for_stable_deleted_grid_vertical_field_json(asset_path);
+        const auto update_process = run_process_capture(
+            studio_host_path,
+            {
+                "--path", asset_path.string(),
+                "--set-property",
+                "--unique-id", "deleted-settings-guid",
+                "--property-name", "GRIDV",
+                "--property-value", updated_grid,
+                "--json"
+            },
+            temp_root);
+
+        if (update_process.exit_code != 0) {
+            std::cerr << "studio host " << label << " stable deleted vertical-grid field update stdout:\n"
+                      << update_process.stdout_text << "\n";
+            std::cerr << "studio host " << label << " stable deleted vertical-grid field update stderr:\n"
+                      << update_process.stderr_text << "\n";
+            std::cerr << "fixture root: " << temp_root << "\n";
+        }
+
+        expect(update_process.exit_code == 0,
+               "#1831: report/label stable deleted vertical-grid field update should exit successfully");
+        const auto grid_property = copperfin::vfp::query_visual_object_property({
+            .path = asset_path.string(),
+            .record_index = 0U,
+            .object_name = {},
+            .unique_id = "deleted-settings-guid",
+            .property_name = "GRIDV"
+        });
+        expect(grid_property.ok && grid_property.exists && grid_property.value == updated_grid,
+               "#1831: report/label stable deleted vertical-grid field update should persist the GRIDV field");
+        expect_contains(update_process.stdout_text, "\"documentTitle\": \"" + title + "\"",
+                        "#1831: report/label stable deleted vertical-grid field update should return refreshed report-layout JSON");
+        if (asset_path.extension() == ".lbx") {
+            expect_contains(update_process.stdout_text, "\"isLabel\": true",
+                            "#1831: label stable deleted vertical-grid field update should retain label identity");
+        }
+        expect_empty_report_layout_preview_bounds(
+            update_process.stdout_text,
+            "#2025: stable-selected deleted report/label vertical-grid update JSON");
+        expect_contains(update_process.stdout_text, "\"pageSetupAvailable\": true",
+                        "#3815: report/label stable deleted vertical-grid field update should expose effective page setup");
+        expect_contains(update_process.stdout_text, "\"gridVerticalAvailable\": true",
+                        "#3815: report/label stable deleted vertical-grid field update should expose effective availability");
+        expect_contains(update_process.stdout_text, "\"gridVertical\": " + updated_grid,
+                        "#3815: report/label stable deleted vertical-grid field update should expose the effective value");
+        expect_contains(update_process.stdout_text, "\"settingCount\": 0",
+                        "#1831: report/label stable deleted vertical-grid field update should not fabricate live settings");
+        expect_contains(update_process.stdout_text, "\"deletedSettingCount\": 4",
+                        "#1831: report/label stable deleted vertical-grid field update should preserve deleted setting counts");
+        expect_contains(update_process.stdout_text, "\"selectedReportSettingsAvailable\": true",
+                        "#1831: report/label stable deleted vertical-grid field update should preserve selected-settings availability");
+        expect_contains(update_process.stdout_text, "\"selectedReportSelectionKind\": \"settings\"",
+                        "#1831: report/label stable deleted vertical-grid field update should preserve settings selection kind");
+        expect_contains_in_order(
+            update_process.stdout_text,
+            {
+                "\"selectedReportSettings\": [",
+                "\"name\": \"TOPMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 0",
+                "\"name\": \"BOTMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 1",
+                "\"name\": \"GRIDH\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 2",
+                "\"name\": \"GRIDV\", \"recordIndex\": 0, \"fieldIndex\": 3, \"sourceLineIndex\": null",
+                "\"value\": \"" + updated_grid + "\""
+            },
+            "#1831: report/label stable deleted vertical-grid field update should refresh selected deleted settings");
+    };
+
+    run_deleted_grid_vertical_update(temp_root / "deleted_grid_vertical_stable.frx",
+                                     "deleted_grid_vertical_stable.frx",
+                                     "12",
+                                     "report");
+    run_deleted_grid_vertical_update(temp_root / "deleted_grid_vertical_stable.lbx",
+                                     "deleted_grid_vertical_stable.lbx",
+                                     "14",
+                                     "label");
+
+    if (failures == 0) {
+        fs::remove_all(temp_root, ignored);
+    }
+}
+
+void test_studio_host_json_clears_deleted_report_grid_vertical_fields_by_stable_selection(
+    const std::string& studio_host_path) {
+    namespace fs = std::filesystem;
+
+    const fs::path temp_root =
+        fs::temp_directory_path() / "copperfin_studio_host_deleted_report_grid_vertical_clear_stable_json_tests";
+    std::error_code ignored;
+    fs::remove_all(temp_root, ignored);
+    fs::create_directories(temp_root);
+
+    const auto run_deleted_grid_vertical_clear = [&](const fs::path& asset_path,
+                                                     const std::string& title,
+                                                     const std::string& label) {
+        write_synthetic_report_table_for_stable_deleted_grid_vertical_field_json(asset_path);
+        const auto clear_process = run_process_capture(
+            studio_host_path,
+            {
+                "--path", asset_path.string(),
+                "--clear-property",
+                "--unique-id", "deleted-settings-guid",
+                "--property-name", "GRIDV",
+                "--json"
+            },
+            temp_root);
+
+        if (clear_process.exit_code != 0) {
+            std::cerr << "studio host " << label << " stable deleted vertical-grid field clear stdout:\n"
+                      << clear_process.stdout_text << "\n";
+            std::cerr << "studio host " << label << " stable deleted vertical-grid field clear stderr:\n"
+                      << clear_process.stderr_text << "\n";
+            std::cerr << "fixture root: " << temp_root << "\n";
+        }
+
+        expect(clear_process.exit_code == 0,
+               "#1831: report/label stable deleted vertical-grid field clear should exit successfully");
+        const auto grid_property = copperfin::vfp::query_visual_object_property({
+            .path = asset_path.string(),
+            .record_index = 0U,
+            .object_name = {},
+            .unique_id = "deleted-settings-guid",
+            .property_name = "GRIDV"
+        });
+        expect(grid_property.ok && grid_property.exists && grid_property.value.empty(),
+               "#1831: report/label stable deleted vertical-grid field clear should blank the GRIDV field");
+        expect_contains(clear_process.stdout_text, "\"documentTitle\": \"" + title + "\"",
+                        "#1831: report/label stable deleted vertical-grid field clear should return refreshed report-layout JSON");
+        if (asset_path.extension() == ".lbx") {
+            expect_contains(clear_process.stdout_text, "\"isLabel\": true",
+                            "#1831: label stable deleted vertical-grid field clear should retain label identity");
+        }
+        expect_empty_report_layout_preview_bounds(
+            clear_process.stdout_text,
+            "#2025: stable-selected deleted report/label vertical-grid clear JSON");
+        expect_contains(clear_process.stdout_text, "\"pageSetupAvailable\": true",
+                        "#3815: report/label stable deleted vertical-grid field clear should preserve effective page setup");
+        expect_contains(clear_process.stdout_text, "\"gridVerticalAvailable\": false",
+                        "#3815: report/label stable deleted vertical-grid field clear should clear effective availability");
+        expect_contains(clear_process.stdout_text, "\"gridVertical\": 0",
+                        "#3815: report/label stable deleted vertical-grid field clear should reset the effective value");
+        expect_contains(clear_process.stdout_text, "\"settingCount\": 0",
+                        "#1831: report/label stable deleted vertical-grid field clear should not fabricate live settings");
+        expect_contains(clear_process.stdout_text, "\"deletedSettingCount\": 3",
+                        "#1831: report/label stable deleted vertical-grid field clear should remove the deleted direct setting from counts");
+        expect_contains(clear_process.stdout_text, "\"selectedReportSettingsAvailable\": true",
+                        "#1831: report/label stable deleted vertical-grid field clear should preserve selected-settings availability");
+        expect_contains(clear_process.stdout_text, "\"selectedReportSelectionKind\": \"settings\"",
+                        "#1831: report/label stable deleted vertical-grid field clear should preserve settings selection kind");
+        expect_contains_in_order(
+            clear_process.stdout_text,
+            {
+                "\"selectedReportSettings\": [",
+                "\"name\": \"TOPMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 0",
+                "\"name\": \"BOTMARGIN\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 1",
+                "\"name\": \"GRIDH\", \"recordIndex\": 0, \"fieldIndex\": 2, \"sourceLineIndex\": 2"
+            },
+            "#1831: report/label stable deleted vertical-grid field clear should preserve remaining selected deleted settings");
+        expect_not_contains(clear_process.stdout_text,
+                            "\"name\": \"GRIDV\", \"recordIndex\": 0, \"fieldIndex\": 3",
+                            "#1831: report/label stable deleted vertical-grid field clear should remove direct GRIDV provenance");
+    };
+
+    run_deleted_grid_vertical_clear(temp_root / "deleted_grid_vertical_clear_stable.frx",
+                                    "deleted_grid_vertical_clear_stable.frx",
+                                    "report");
+    run_deleted_grid_vertical_clear(temp_root / "deleted_grid_vertical_clear_stable.lbx",
+                                    "deleted_grid_vertical_clear_stable.lbx",
+                                    "label");
+
+    if (failures == 0) {
+        fs::remove_all(temp_root, ignored);
+    }
+}