code · pull · Feb 5, 2026 · Feb 5, 2026 · Feb 5, 2026 · Feb 5, 2026
diff --git a/.rulesync/rules/ag-grid.md b/.rulesync/rules/ag-grid.md
@@ -80,7 +80,10 @@ For detailed information about preferred technologies and architectural constrai
 -   `yarn nx build:package <package>` – create ESM/CJS bundles to validate publishable output.
 -   `yarn nx build:umd <package>` – produce UMD bundles for browser distribution smoke-tests.
 -   `yarn nx run-many -t build` – rebuild all packages when changes span the dependency graph.
--   `yarn nx test <package>` – execute Jest suites for the affected package.
+-   `yarn nx test ag-behavioural-testing --run` – run behavioural tests in `testing/behavioural/` (primary test suite, uses Vitest).
+-   `yarn nx test ag-behavioural-testing --run "<file-pattern>"` – run specific behavioural test file.
+-   `yarn nx test ag-behavioural-testing --run "<file-pattern>" -t "<test-name>"` – run specific behavioural test by name.
+-   `yarn nx test <package>` – execute Jest unit tests for the affected package.
 -   `yarn nx test <package> --testPathPattern="<file-name>"` - test specific test file
 -   `yarn nx test <package> --testPathPattern="<file-name>" --testNamePattern="<test-name>"` - test specific test name in a specific test file
 -   `yarn nx e2e <package>` – run Playwright flows when altering website behaviour.
@@ -128,11 +131,11 @@ Core dependency chain: `ag-grid-community` → `ag-grid-enterprise` → framewor
 
 For comprehensive testing information, see [Testing Guide](.rulesync/rules/testing.md).
 
-Key testing tools:
+**Behavioural tests are the primary test suite.** When verifying grid changes, run behavioural tests first. Key testing tools:
 
--   **Unit tests**: Jest with jsdom environment
+-   **Behavioural tests** (primary): `testing/behavioural/` for grid behaviour verification — use Vitest
+-   **Unit tests**: Jest with jsdom environment for package-level tests
 -   **E2E tests**: Playwright for website interaction testing
--   **Behavioural tests**: `testing/behavioural/` for grid behaviour verification
 -   **Accessibility tests**: `testing/accessibility/` for a11y compliance
 -   **Performance tests**: `testing/performance/` for performance regression testing
 

diff --git a/.rulesync/rules/testing.md b/.rulesync/rules/testing.md
@@ -8,6 +8,16 @@ globs: ['**/*.test.ts', '**/*.spec.ts', 'testing/**/*']
 
 This guide covers testing strategies and best practices for the AG Grid codebase.
 
+## Behavioural Tests — Primary Test Suite
+
+Behavioural tests in `testing/behavioural/` are the primary test suite for AG Grid. They test the grid as a **black box**, instantiating the full grid to verify complex behaviours and features.
+
+**Key principles:**
+
+-   The unit under test is a **behaviour**, not a function, class, method, or file
+-   **Avoid mocking** — prefer fakes instead (e.g., fake DOM)
+-   Test at the edges of the system to ensure real integration using public APIs
+
 ## Test Structure
 
 ### Directory Layout
@@ -35,41 +45,51 @@ packages/ag-grid-community/src/
 
 ## Running Tests
 
-### Unit Tests (Jest)
+### Behavioural Tests (Vitest) – Primary Test Suite
 
-Unit tests in `packages/` use Jest. Use `--testPathPattern` and `--testNamePattern`:
+Behavioural tests in `testing/behavioural/` are the primary test suite for verifying grid behaviour. They use Vitest via Nx. Use `--run` to execute once (without watch mode):
 
 ```bash
-# Run all tests for a package
-yarn nx test ag-grid-community
+# Run all behavioural tests
+yarn nx test ag-behavioural-testing --run
 
 # Run specific test file
-yarn nx test ag-grid-community --testPathPattern="featureName"
+yarn nx test ag-behavioural-testing --run "cell-editing-regression"
 
 # Run specific test by name
-yarn nx test ag-grid-community --testPathPattern="featureName" --testNamePattern="should handle"
+yarn nx test ag-behavioural-testing --run "cell-editing-regression" -t "should handle"
 ```
 
-### E2E Tests
+### Benchmarks
 
 ```bash
-# Run documentation E2E tests
-yarn nx e2e ag-grid-docs
+# Run all benchmarks
+yarn nx run ag-behavioural-testing:benchmark
+
+# Run specific benchmark file
+yarn nx run ag-behavioural-testing:benchmark -- src/tree-data/datapath/benchmarks/tree-data-path.bench.ts
 ```
 
-### Behavioural Tests (Vitest)
+### Unit Tests (Jest)
 
-Behavioural tests in `testing/behavioural/` use Vitest via Nx. Use `--run` to execute once (without watch mode):
+Unit tests in `packages/` use Jest. Use `--testPathPattern` and `--testNamePattern`:
 
 ```bash
-# Run all behavioural tests
-yarn nx test ag-behavioural-testing --run
+# Run all tests for a package
+yarn nx test ag-grid-community
 
 # Run specific test file
-yarn nx test ag-behavioural-testing --run "cell-editing-regression"
+yarn nx test ag-grid-community --testPathPattern="featureName"
 
 # Run specific test by name
-yarn nx test ag-behavioural-testing --run "cell-editing-regression" -t "should handle"
+yarn nx test ag-grid-community --testPathPattern="featureName" --testNamePattern="should handle"
+```
+
+### E2E Tests
+
+```bash
+# Run documentation E2E tests
+yarn nx e2e ag-grid-docs
 ```
 
 **Note:** Vitest does not support `--testPathPattern` or `--testNamePattern`. Use positional arguments for file matching and `-t` for test name filtering.

diff --git a/.snyk b/.snyk
@@ -79,4 +79,15 @@ ignore:
                   developer machines
               expires: 2026-06-08T00:00:00.000Z
               created: 2025-01-05T10:10:00.000Z
+    SNYK-JS-ISAACSBRACEEXPANSION-15208653:
+        - 'glob@11.1.0 > minimatch@10.1.1 > @isaacs/brace-expansion@5.0.0':
+              reason: >-
+                  braces is only used in development/testing - it's not used in the final production build
+              expires: 2026-06-08T00:00:00.000Z
+              created: 2025-01-05T10:10:00.000Z
+        - '@nx/rollup@20.3.1 > rollup-plugin-copy@3.5.0 > globby@10.0.1 > @types/glob@7.2.0 > @types/minimatch@6.0.0 > minimatch@10.1.1 > @isaacs/brace-expansion@5.0.0':
+              reason: >-
+                  braces is only used in development/testing - it's not used in the final production build
+              expires: 2026-06-08T00:00:00.000Z
+              created: 2025-01-05T10:10:00.000Z
 patch: {}
diff --git a/AGENTS.md b/AGENTS.md
@@ -1,3 +1,7 @@
+# Additional Conventions Beyond the Built-in Functions
+
+As this project's AI coding tool, you must follow the additional conventions below, in addition to the built-in functions.
+
 ## AI Agent Instructions
 
 This file provides guidance to AI Agents when working with code in this repository.
@@ -73,7 +77,10 @@ For detailed information about preferred technologies and architectural constrai
 -   `yarn nx build:package <package>` – create ESM/CJS bundles to validate publishable output.
 -   `yarn nx build:umd <package>` – produce UMD bundles for browser distribution smoke-tests.
 -   `yarn nx run-many -t build` – rebuild all packages when changes span the dependency graph.
--   `yarn nx test <package>` – execute Jest suites for the affected package.
+-   `yarn nx test ag-behavioural-testing --run` – run behavioural tests in `testing/behavioural/` (primary test suite, uses Vitest).
+-   `yarn nx test ag-behavioural-testing --run "<file-pattern>"` – run specific behavioural test file.
+-   `yarn nx test ag-behavioural-testing --run "<file-pattern>" -t "<test-name>"` – run specific behavioural test by name.
+-   `yarn nx test <package>` – execute Jest unit tests for the affected package.
 -   `yarn nx test <package> --testPathPattern="<file-name>"` - test specific test file
 -   `yarn nx test <package> --testPathPattern="<file-name>" --testNamePattern="<test-name>"` - test specific test name in a specific test file
 -   `yarn nx e2e <package>` – run Playwright flows when altering website behaviour.
@@ -121,11 +128,11 @@ Core dependency chain: `ag-grid-community` → `ag-grid-enterprise` → framewor
 
 For comprehensive testing information, see [Testing Guide](.rulesync/rules/testing.md).
 
-Key testing tools:
+**Behavioural tests are the primary test suite.** When verifying grid changes, run behavioural tests first. Key testing tools:
 
--   **Unit tests**: Jest with jsdom environment
+-   **Behavioural tests** (primary): `testing/behavioural/` for grid behaviour verification — use Vitest
+-   **Unit tests**: Jest with jsdom environment for package-level tests
 -   **E2E tests**: Playwright for website interaction testing
--   **Behavioural tests**: `testing/behavioural/` for grid behaviour verification
 -   **Accessibility tests**: `testing/accessibility/` for a11y compliance
 -   **Performance tests**: `testing/performance/` for performance regression testing
 
@@ -139,6 +146,12 @@ Essential practices:
 -   Self-review your changes before proposing commits
 -   Ensure tests exercise real implementations, not test helpers
 
+#### Styling
+
+The grid is in transition from Legacy Themes (.scss files written in Sass under `/community-modules/styles/`) to the Theming API (.css written in modern nested CSS under `/packages/`).
+
+While this transition is in progress, changes made to Theming API should be applied to Legacy Themes. When reviewing a PR with changes to the Theming API CSS, if the same PR does not have corresponding changes to Legacy Themes, this should be flagged as a P1 level issue.
+
 ### Common Development Tasks
 
 #### Quick Playbooks

diff --git a/community-modules/locale/src/en-US.ts b/community-modules/locale/src/en-US.ts
@@ -220,8 +220,8 @@ export const AG_GRID_LOCALE_EN = {
     noAggregation: 'None',
     autosizeThisColumn: 'Autosize This Column',
     autosizeAllColumns: 'Autosize All Columns',
-    groupBy: 'Group by',
-    ungroupBy: 'Un-Group by',
+    groupBy: 'Group by ${variable}',
+    ungroupBy: 'Un-Group by ${variable}',
     ungroupAll: 'Un-Group All',
     addToValues: 'Add ${variable} to values',
     removeFromValues: 'Remove ${variable} from values',

diff --git a/documentation/ag-grid-docs/src/content/docs-nav/nav.json b/documentation/ag-grid-docs/src/content/docs-nav/nav.json
@@ -55,6 +55,10 @@
                             "title": "Creating a Basic Grid",
                             "path": "deep-dive"
                         },
+                        {
+                            "title": "Styling a Grid",
+                            "path": "styling-tutorial"
+                        },
                         {
                             "title": "Best Practices",
                             "path": "react-hooks",

diff --git a/documentation/ag-grid-docs/src/content/docs/filter-date/index.mdoc b/documentation/ag-grid-docs/src/content/docs/filter-date/index.mdoc
@@ -274,7 +274,7 @@ const columnDefs: ColDef[] = [
 `Start Of Today`, `Start Of Tomorrow`, `Start Of XXX` point to the beginning of the corresponding day, e.g. `00:00:00.000` in the browser’s local time zone.
 {% /note %}
 
-For date range filters, the Grid State model matches the SSRM request model shape. See [SSRM Date Range Filters](./server-side-model-filtering/#preset-date-range-filters) for the server-side filtering contract.
+For date range filters, the Grid State model matches the SSRM request model shape. See [SSRM Preset Date Range Filters](./server-side-model-filtering/#preset-date-range-filters) for the server-side filtering contract.
 
 ## Range Input Validation and Error States
 

diff --git a/documentation/ag-grid-docs/src/content/docs/formulas/index.mdoc b/documentation/ag-grid-docs/src/content/docs/formulas/index.mdoc
@@ -5,6 +5,8 @@ enterprise: true
 
 Formulas let users enter spreadsheet-style expressions into grid cells so values update automatically when referenced data changes.
 
+{% video videoSrc="resources/formula-editor-demo.mp4" centered=true /%}
+
 ## Enabling Formulas
 
 To enable formulas, set the column property `allowFormula: true` on one or more columns and ensure your rows have [Row IDs](./row-ids/#row-ids).

diff --git a/documentation/ag-grid-docs/src/content/docs/formulas/resources/formula-editor-demo-dark.mp4 b/documentation/ag-grid-docs/src/content/docs/formulas/resources/formula-editor-demo-dark.mp4
diff --git a/documentation/ag-grid-docs/src/content/docs/formulas/resources/formula-editor-demo.mp4 b/documentation/ag-grid-docs/src/content/docs/formulas/resources/formula-editor-demo.mp4
diff --git a/documentation/ag-grid-docs/src/content/docs/installation/index.mdoc b/documentation/ag-grid-docs/src/content/docs/installation/index.mdoc
@@ -96,7 +96,7 @@ You can test AG Grid Enterprise locally without a licence. To test in production
 {% /if %}
 
 {% if isFramework("react") %}
-Use `AgGridProvider` to provide modules to all grid instances. Provide `AllCommunityModule` to access all Community features or `AllEnterpriseModule` to access all Community **_and_** Enterprise features:
+Use `AgGridProvider` to provide modules and a license key (enterprise only) to all grid instances. Provide `AllCommunityModule` to access all Community features or `AllEnterpriseModule` to access all Community **_and_** Enterprise features:
 
 ```jsx
 import { AllCommunityModule } from 'ag-grid-community';
@@ -107,7 +107,7 @@ const modules = [AllCommunityModule];
 
 function App() {
     return (
-        <AgGridProvider modules={modules}>
+        <AgGridProvider modules={modules} licenseKey="YOUR_LICENSE_KEY">
             <AgGridReact /* ... props */ />
         </AgGridProvider>
     );

diff --git a/documentation/ag-grid-docs/src/content/docs/pivoting/index.mdoc b/documentation/ag-grid-docs/src/content/docs/pivoting/index.mdoc
@@ -89,15 +89,15 @@ const gridOptions = {
 
 ## Pivot Mode vs Pivot Active
 
-It is possible to have pivot mode turned on even though there is no pivot active on the grid. In this scenario, the grid will display the data as normal but will strip out columns that have no grouping or value active.
+It is possible to have pivot mode turned on even though there is no pivot active, on the grid. A pivot is active when one or more of the pivot columns is used as a column label. In this scenario, the grid will display the data as normal but will strip out columns that have no grouping or value active.
 
 The example below demonstrates the difference between pivot mode and having a column with pivot active. The example has three modes of operation that can be switched between using the top buttons. The modes are as follows:
 
 -   **1 - Grouping Active:** This is normal grouping. The grid groups with aggregations over Gold, Silver and Bronze. The user can drill down to the lowest level row data and columns without aggregation or group (eg Country, Year, Date and Sport) are shown.
 
--   **2 - Grouping Active with Pivot Mode:** This is grouping with pivotMode=true, but without any pivot active. The data shown is identical to the first option except the grid removes access to the lowest level row data and columns without aggregation or group are not shown.
+-   **2 - Grouping Active with Pivot Mode:** This is grouping with `pivotMode=true`, but without any pivot active. The data shown is identical to the first option except the grid removes access to the lowest level row data and columns without aggregation or group are not shown.
 
--   **3 - Grouping Active with Pivot Mode and Pivot Active:** This is grouping with pivotMode=true and pivot active. Although it appears similar to the second option, there is no pivot active in the second option.
+-   **3 - Grouping Active with Pivot Mode and Pivot Active:** This is grouping with pivotMode=true and pivot active. Note that the Year column has been added to the Column Labels and there are now pivot result columns for each year.
 
 {% gridExampleRunner title="Pivot Mode Vs Pivot Active" name="pivot-mode"  exampleHeight=630 /%}