feat: automatic module directories

.github/workflows/test.yml

@@ -146,3 +146,30 @@ jobs:
           version: ${{ matrix.version }}
           working-directory: sample-plugins
           args: --timeout=5m --issues-exit-code=0 ./...
+
+  test-monorepo:
+    needs: [ build ]
+    strategy:
+      matrix:
+        os:
+          - ubuntu-latest
+          - ubuntu-22.04-arm
+          - macos-latest
+          - windows-latest
+    runs-on: ${{ matrix.os }}
+    permissions:
+      contents: read
+      pull-requests: read
+    steps:
+      - uses: actions/checkout@v5
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 24.x
+      - uses: actions/setup-go@v6
+        with:
+          go-version: oldstable
+      - uses: ./
+        with:
+          working-directory: sample-monorepo
+          experimental: "automatic-module-directories"
+          args: --timeout=5m --issues-exit-code=0 ./...

README.md

@@ -275,6 +275,7 @@ You will also likely need to add the following `.gitattributes` file to ensure t
 | [`skip-save-cache`](#skip-save-cache)                         | Don't save cache.                                  |
 | [`cache-invalidation-interval`](#cache-invalidation-interval) | Number of days before cache invalidation.          |
 | [`problem-matchers`](#problem-matchers)                       | Forces the usage of the embedded problem matchers. |
+| [Experimental](#experimental)                                 | Experimental options                               |
 
 ### Installation
 
@@ -552,6 +553,47 @@ with:
 
 </details>
 
+### Experimental
+
+The following options are experimental: those may or may not be supported in the future, and so they will be either converted into a dedicated option or removed.
+
+List of comma-separated options.
+
+<details>
+<summary>Example</summary>
+
+```yaml
+uses: golangci/golangci-lint-action@v9
+with:
+  experimental: "foo,bar"
+```
+
+</details>
+
+#### `automatic-module-directories`
+
+(optional)
+
+This option will run golangci-lint in each module directory, useful for monorepos.
+
+The automatic detection of modules uses the `working-directory` as the base directory if defined, otherwise the root directory.
+
+> [!IMPORTANT]
+> - The cache key will refer to the `working-directory` (if defined) because all the golangci-lint runs must use the same cache directory/key.
+> - The version detection will only work if the project has a single module.
+> - If the project has multiple modules, the custom build file must be located in the repository root ( or `working-directory`).
+
+<details>
+<summary>Example</summary>
+
+```yaml
+uses: golangci/golangci-lint-action@v9
+with:
+  experimental: "automatic-module-directories"
+```
+
+</details>
+
 ## Annotations
 
 Currently, GitHub parses the action's output and creates [annotations](https://github.blog/2018-12-14-introducing-check-runs-and-annotations/).

action.yml

@@ -65,6 +65,12 @@ inputs:
       example: "cache,clean"
     default: ""
     required: false
+  experimental:
+    description: |
+      Experimental options for the action.
+      List of comma separated options.
+    default: ""
+    required: false
 runs:
   using: "node24"
   main: "dist/run/index.js"