diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index f0624e5..a393c10 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -1,3 +1,3 @@
 # Testing your contribution:
 
-The GitHub Actions [Test workflow](https://github.com/jidicula/clang-format-action/actions/workflows/test.yml) is triggered on PR submission. It runs [`test/test.sh`](https://github.com/jidicula/clang-format-action/blob/main/test/test.sh) on the [test files](https://github.com/jidicula/clang-format-action/tree/main/test). Run this script locally to test your changes. If you're adding checking functionality for new file extensions, add test files that are known to pass this Action's check and known to fail this Action's check, in `test/known_pass` and `test/known_fail` respectively.
+The GitHub Actions [Tests workflow](https://github.com/jidicula/clang-format-action/actions/workflows/tests.yml) is triggered on PR submission. It runs [`test/test.sh`](https://github.com/jidicula/clang-format-action/blob/main/test/test.sh) on the [test files](https://github.com/jidicula/clang-format-action/tree/main/test). Run this script locally to test your changes. If you're adding checking functionality for new file extensions, add test files that are known to pass this action's check and known to fail this action's check, in `test/known_pass` and `test/known_fail` respectively.
diff --git a/README.md b/README.md
index 29b89ed..e2bbfd1 100644
--- a/README.md
+++ b/README.md
@@ -4,9 +4,9 @@
 
 
 # clang-format-action
-GitHub Action for `clang-format` checks. Note that this Action does **NOT** format your code for you - it only verifies that your repository's code follows your project's formatting conventions.
+An action for `clang-format` checks. This action does **NOT** format your code for you - it only verifies that your repository's code follows your project's formatting conventions.
 
-You can define your own formatting rules in a `.clang-format` file at your repository root, or you can provide a fallback style (see [`fallback-style`](#inputs)). You can also provide a path to check. If you want to run checks against multiple paths in your repository, you can use this Action in a [matrix run](#multiple-paths).
+You can define your own formatting rules in a `.clang-format` file at your repository root, or you can provide a fallback style (see [`fallback-style`](#inputs)). You can also provide a path to check. If you want to run checks against multiple paths in your repository, you can use this action in a [matrix run](#multiple-paths).
 
 ## Major versions supported
 * 3: `clang-format-3.9`
@@ -17,7 +17,7 @@ You can define your own formatting rules in a `.clang-format` file at your repos
 * 8: `clang-format-8`
 * 9: `clang-format-9`
 * 10: `clang-format-10`
-* 11:  `clang-format-11`
+* 11: `clang-format-11`
 * 12: `clang-format-12`
 * 13: `clang-format-13`
 * 14: `clang-format-14`
@@ -26,6 +26,14 @@ You can define your own formatting rules in a `.clang-format` file at your repos
 * 17: `clang-format-17`
 * 18: `clang-format-18`
 
+## Action version upgrade guarantee
+
+> [!IMPORTANT]
+> This action complies with the [Semantic Versioning spec](https://semver.org) for how it's called from GitHub Actions workflows. This means that for version format `x.y.z`, minor and patch version increments `y++` and `z++` will not break existing functionality for how this action is called in your GitHub Actions workflows. Major version increments (`x++`) *will* include breaking changes in how this action is called. If you notice version changes that violate this guarantee, [open an issue](https://github.com/jidicula/clang-format-action/issues/new?template=Blank+issue) and let's work together to fix it 😁.
+
+> [!CAUTION]
+> I provide no guarantees for formatting breakages *within* `clang-format` versions. This action only supports major versions of `clang-format` and doesn't support granular specification of `clang-format` minor or patch versions. It's possible that a formatting check workflow using this action and a pinned version of `clang-format` could break in a subsequent run if the underlying `clang-format` Ubuntu package has introduced a breaking minor or patch version change. I'm not sure how often this happens - vote in [this poll](https://github.com/jidicula/clang-format-action/discussions/192) and optionally leave a comment so I can understand this problem more.
+
 ## Do you find this useful?
 
 You can sponsor me [here](https://github.com/sponsors/jidicula)!
@@ -42,10 +50,10 @@ You can sponsor me [here](https://github.com/sponsors/jidicula)!
   * Available values: `LLVM`, `Google`, `Chromium`, `Mozilla`, `WebKit` and others listed in the `clang-format` [docs for BasedOnStyle](https://clang.llvm.org/docs/ClangFormatStyleOptions.html#configurable-format-style-options).
 * `exclude-regex` [optional]: A regex to exclude files or directories that should not be checked.
   * Default: `^$`
-  * Pattern matching is done with a POSIX `grep -E` extended regex, **not** a glob expression. You can exclude multiple patterns like this: `(hello|world)`. Build and verify your regex at https://regex101.com .
+  * Pattern matching is done with a POSIX `grep -E` extended regex, **not** a glob expression. You can exclude multiple patterns like this: `(hello|world)`. Build and verify your regex at [regex101.com](https://regex101.com) ([example](https://regex101.com/r/llFcLy/7)).
 * `include-regex` [optional]: A regex to include files or directories that should be checked.
-  * Default: `^.*\.((((c|C)(c|pp|xx|\+\+)?$)|((h|H)h?(pp|xx|\+\+)?$))|(ino|pde|proto|cu))$`
-  * Pattern matching is done with a POSIX `grep -E` extended regex, **not** a glob expression. You can exclude multiple patterns like this: `(hello|world)`. Build and verify your regex at https://regex101.com .
+  * Default: see [`INCLUDE_REGEX`](./check.sh#77)
+  * Pattern matching is done with a POSIX `grep -E` extended regex, **not** a glob expression. You can exclude multiple patterns like this: `(hello|world)`. Build and verify your regex at [regex101.com](https://regex101.com) ([example](https://regex101.com/r/llFcLy/7)).
 
 This action checks all C/C++/Protobuf (including Arduino `.ino` and `.pde`) files in the provided directory in the GitHub workspace are formatted correctly using `clang-format`. If no directory is provided or the provided path is not a directory in the GitHub workspace, all C/C++/Protobuf files are checked.
 
@@ -77,7 +85,8 @@ The following file extensions are checked by default:
 
 # Usage
 
-⚠️This action does not run on `windows` GitHub Actions runners!
+> [!WARNING]
+> This action is not supported on `windows` GitHub Actions runners!
 
 ## Single Path
 
@@ -91,9 +100,9 @@ jobs:
     name: Formatting Check
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Run clang-format style check for C/C++/Protobuf programs.
-      uses: jidicula/clang-format-action@v4.11.0
+      uses: jidicula/clang-format-action@v4.12.0
       with:
         clang-format-version: '13'
         check-path: 'src'
@@ -116,9 +125,9 @@ jobs:
           - 'src'
           - 'examples'
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Run clang-format style check for C/C++/Protobuf programs.
-      uses: jidicula/clang-format-action@v4.11.0
+      uses: jidicula/clang-format-action@v4.12.0
       with:
         clang-format-version: '13'
         check-path: ${{ matrix.path }}
@@ -143,9 +152,9 @@ jobs:
           - check: 'examples'
             exclude: ''              # Nothing to exclude
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Run clang-format style check for C/C++/Protobuf programs.
-      uses: jidicula/clang-format-action@v4.11.0
+      uses: jidicula/clang-format-action@v4.12.0
       with:
         clang-format-version: '13'
         check-path: ${{ matrix.path['check'] }}
@@ -155,4 +164,4 @@ jobs:
 
 # Who uses this?
 
-[These public repos](https://github.com/search?o=desc&q=uses%3A+jidicula%2Fclang-format-action+-user%3Ajidicula&s=indexed&type=Code) use this Action.
+[These public repos](https://github.com/search?q=%22uses%3A+jidicula%2Fclang-format-action%22+-user%3Ajidicula&type=code) use this Action.
diff --git a/SECURITY.md b/SECURITY.md
index 4d4cd21..0b3d587 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -2,10 +2,10 @@
 
 ## Supported Versions
 
-| Version | Supported          |
-| ------- | ------------------ |
-| 4.11.x   | :white_check_mark: |
-| < 4.11.x | :x:                |
+| Version  | Supported          |
+|----------|--------------------|
+| 4.12.x   | :white_check_mark: |
+| < 4.12.x | :x:                |
 
 ## Reporting a Vulnerability