diff --git a/modules/languages/siren-yaml.el b/modules/languages/siren-yaml.el
index 26cc571..366763d 100644
--- a/modules/languages/siren-yaml.el
+++ b/modules/languages/siren-yaml.el
@@ -9,6 +9,32 @@
 (require 'siren-lsp)
 (require 'siren-prog-mode)
 
+(defun siren-yaml-is-github-actions-workflow-p ()
+  "Return non-nil if current buffer is a GitHub Actions workflow.
+
+This is determined by checking if the buffer is visiting a *.yml
+or *.yaml file in a .github/workflows/ directory."
+  (and (buffer-file-name)
+       (string-match-p "\\.github/workflows/$"
+                       (file-name-directory (buffer-file-name)))
+       (string-match-p "\\.ya?ml$" (buffer-file-name))))
+
+(defun siren-flycheck-setup-yaml-actionlint()
+  (with-eval-after-load 'flycheck
+    (flycheck-def-executable-var yaml-actionlint "actionlint")
+    (flycheck-define-checker yaml-actionlint
+      "A GitHub Actions workflow checker using actionlint."
+      :command ("actionlint" "-oneline" "-")
+      :standard-input t
+      :error-patterns
+      ((error
+        line-start "<stdin>:" line ":" column ": " (message) line-end)
+       (error
+        line-start (file-name) ":" line ":" column ": " (message) line-end))
+      :predicate siren-yaml-is-github-actions-workflow-p
+      :modes (yaml-mode yaml-ts-mode))
+    (add-to-list 'flycheck-checkers 'yaml-actionlint)))
+
 (use-package yaml-mode
   :mode "\\.yml\\'" "\\.yaml\\'"
   :general
@@ -21,7 +47,10 @@
   :preface
   (defun siren-yaml-mode-setup ()
     (run-hooks 'prog-mode-hook)
-    (setq-local tab-width 2)))
+    (setq-local tab-width 2))
+
+  :config
+  (siren-flycheck-setup-yaml-actionlint))
 
 (use-package lsp-yaml
   :straight lsp-mode
@@ -31,13 +60,28 @@
 
   :preface
   (defun siren-lsp-yaml-mode-setup ()
-    (lsp-deferred)
-    (lsp-format-buffer-on-save-mode)))
+    (lsp)
+    (lsp-format-buffer-on-save-mode)
+    (when (and (fboundp 'flycheck-select-checker)
+               (siren-yaml-is-github-actions-workflow-p)
+               (executable-find "actionlint"))
+      (flycheck-select-checker 'yaml-actionlint)
+      (flycheck-add-next-checker 'yaml-actionlint 'lsp))))
 
 (use-package yaml-imenu
   :after yaml-mode
   :config
   (yaml-imenu-enable))
 
+(use-package yaml-ts-mode
+  :straight (:type built-in)
+  :after yaml-mode
+  :if (fboundp 'yaml-ts-mode)
+  :hook (yaml-ts-mode . siren-yaml-ts-mode-setup)
+
+  :preface
+  (defun siren-yaml-ts-mode-setup ()
+    (run-hooks 'yaml-mode-hook)))
+
 (provide 'siren-yaml)
 ;;; siren-yaml.el ends here