diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index b042dfce5..deaf4c6d5 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -50,7 +50,7 @@ jobs:
       - name: Dog fooding 🐶
         run: |
           echo "::add-matcher::.github/actionlint-matcher.json"
-          ./actionlint -color
+          ./actionlint -color -input-format=workflow
       - uses: codecov/codecov-action@v3
         with:
           env_vars: OS
@@ -116,6 +116,6 @@ jobs:
         run: docker container run
           --mount type=bind,source="$(pwd)",target=/mnt/app
           --workdir /mnt/app
-          -- ${{ steps.image.outputs.digest }} -color -verbose
+          -- ${{ steps.image.outputs.digest }} -color -verbose -input-format=workflow
       - name: Lint Dockerfile with hadolint
         run: docker run --rm -i hadolint/hadolint hadolint --ignore DL3018 --strict-labels - < Dockerfile
diff --git a/ast.go b/ast.go
index bfd86df5f..e92cfffe4 100644
--- a/ast.go
+++ b/ast.go
@@ -422,9 +422,9 @@ func (e *ExecRun) Kind() ExecKind {
 	return ExecKindRun
 }
 
-// Input is an input field for running an action.
+// StepInput is an input field for running an action.
 // https://docs.github.com/en/actions/learn-github-actions/workflow-syntax-for-github-actions#jobsjob_idstepswith
-type Input struct {
+type StepInput struct {
 	// Name is a name of the input.
 	Name *String
 	// Value is a value of the input.
@@ -437,7 +437,7 @@ type ExecAction struct {
 	// https://docs.github.com/en/actions/learn-github-actions/workflow-syntax-for-github-actions#jobsjob_idstepsuses
 	Uses *String
 	// Inputs represents inputs to the action to execute in 'with' section. Keys are in lower case since they are case-insensitive.
-	Inputs map[string]*Input
+	Inputs map[string]*StepInput
 	// Entrypoint represents optional 'entrypoint' field in 'with' section. Nil field means nothing specified
 	// https://docs.github.com/en/actions/learn-github-actions/workflow-syntax-for-github-actions#jobsjob_idstepswithentrypoint
 	Entrypoint *String
@@ -897,6 +897,132 @@ type Workflow struct {
 	Jobs map[string]*Job
 }
 
+// ActionInput is an input field to define the parameters that an action accepts.
+// https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#inputs
+// TODO This kinda duplicates `ActionMetadataInput` from `action_metadata.go`. Merge them?
+type ActionInput struct {
+	// Description is the description of the input.
+	Description *String
+	// Required is a flag to show if the input is required or not.
+	Required *Bool
+	// Default is a default value of the input. It can be nil when no default value is specified.
+	Default *String
+	// DeprecationMessage is a message to show when the input is deprecated.
+	DeprecationMessage *String
+	// Pos is a position in source.
+	Pos *Pos
+}
+
+// ActionOutput is an output field to that is set by this action.
+// https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#outputs-for-docker-container-and-javascript-actions
+// https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#outputs-for-composite-actions
+type ActionOutput struct {
+	// Description is the description of the input.
+	Description *String
+	// Value contains the expression that defions the value; for composite action only (nil otherwise)
+	Value *String
+	// Pos is a position in source.
+	Pos *Pos
+}
+
+// Branding defines what badges to be shown in GitHub Marketplace for actions.
+// https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#branding
+type Branding struct {
+	// Color defines the background color of the badge.
+	Color *String
+	// Icon to use
+	Icon *String
+}
+
+// ActionKind is kind of how the action is executed (JavaScript, Docker or Composite)
+type ActionKind uint8
+
+const (
+	// ActionKindJavascript is kind for actions implemented as node.js scripts
+	ActionKindJavascript ActionKind = iota
+	// ActionKindDockerContainer is kind for actions implemented as docker images
+	ActionKindDockerContainer
+	// ActionKindComposite is kind for actions implemented as composite actions (sequence of steps)
+	ActionKindComposite
+)
+
+// ActionRuns is an interface how the action is executed. Action can be executed as JavaScript, Docker or composite steps.
+type ActionRuns interface {
+	// Kind returns kind of the Action run
+	Kind() ActionKind
+}
+
+// DockerContainerRuns defines how to run an action implemented as docker container
+// https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#runs-for-docker-container-actions
+type DockerContainerRuns struct {
+	// Image specifies the container image to use
+	Image *String
+	// PreEntrypoint specifices an entrypoint to run before the main script
+	PreEntrypoint *String
+	// Entrypoint specifices an entrypoint to run as main action
+	Entrypoint *String
+	// Entrypoint specifices an entrypoint to run as main action
+	Args []*String
+	// Inputs is a mapping of environment variables to pass to the container
+	Env *Env
+	// PostEntrypoint specifices an entrypoint to run at the end of the job
+	PostEntrypoint *String
+}
+
+func (e *DockerContainerRuns) Kind() ActionKind {
+	return ActionKind(ActionKindDockerContainer)
+}
+
+type JavaScriptRuns struct {
+	// https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#runs-for-javascript-actions
+	// Using specifies the specific node runtime (node18, node20 ..)
+	Using *String
+	// Main specifies the entrypoint of the action.
+	Main *String
+	// Pre specifices an entrypoint to run before the main script
+	Pre *String
+	// PreIf defines an expression whether the pre script should be run
+	PreIf *String
+	// Post specifices an entrypoint to run at the end of the job
+	Post *String
+	// PostIf specifies an expression whether the post script should be run
+	PostIf *String
+}
+
+func (e *JavaScriptRuns) Kind() ActionKind {
+	return ActionKind(ActionKindJavascript)
+}
+
+// CompositeRuns is configuration how to run composite action at the step.
+// https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#runs-for-composite-actions
+type CompositeRuns struct {
+	// Steps specifies the steps to run (as in workflow job steps)
+	Steps []*Step
+}
+
+func (e *CompositeRuns) Kind() ActionKind {
+	return ActionKind(ActionKindComposite)
+}
+
+// Action is root of action syntax tree, which represents one action metadata file.
+// https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions
+type Action struct {
+	// Name is the name of the action.
+	Name *String
+	// Author is name of the action's author. This field can be nil when user didn't specify it.
+	Author *String
+	// Description is the description of the action.
+	Description *String
+	// Inputs is a mapping from the input ID to input attributes . This field can be nil when user didn't specify it.
+	Inputs map[string]*ActionInput
+	// Outputs is list of outputs of the action. This field can be nil when user didn't specify it.
+	Outputs map[string]*ActionOutput
+	// Branding defines what badges to be shown in GitHub Marketplace.
+	Branding *Branding
+	// Runs specifies how the action is executed (via JavaScript, Docker or composite steps)
+	Runs ActionRuns
+}
+
 // FindWorkflowCallEvent returns workflow_call event node if exists
 func (w *Workflow) FindWorkflowCallEvent() (*WorkflowCallEvent, bool) {
 	for _, e := range w.On {
diff --git a/command.go b/command.go
index ffac07831..b89dbe1fa 100644
--- a/command.go
+++ b/command.go
@@ -4,6 +4,7 @@ import (
 	"flag"
 	"fmt"
 	"io"
+	"os"
 	"runtime"
 	"runtime/debug"
 )
@@ -77,6 +78,15 @@ type Command struct {
 	Stderr io.Writer
 }
 
+func isDir(path string) bool {
+	// use a switch to make it a bit cleaner
+	fi, err := os.Stat(path)
+	if err != nil {
+		return false
+	}
+	return fi.IsDir()
+}
+
 func (cmd *Command) runLinter(args []string, opts *LinterOptions, initConfig bool) ([]*Error, error) {
 	l, err := NewLinter(cmd.Stdout, opts)
 	if err != nil {
@@ -91,6 +101,10 @@ func (cmd *Command) runLinter(args []string, opts *LinterOptions, initConfig boo
 		return l.LintRepository(".")
 	}
 
+	if len(args) == 1 && isDir(args[0]) {
+		return l.LintDirInRepository(args[0])
+	}
+
 	if len(args) == 1 && args[0] == "-" {
 		b, err := io.ReadAll(cmd.Stdin)
 		if err != nil {
@@ -142,6 +156,7 @@ func (cmd *Command) Main(args []string) int {
 	flags.BoolVar(&opts.Debug, "debug", false, "Enable debug output (for development)")
 	flags.BoolVar(&ver, "version", false, "Show version and how this binary was installed")
 	flags.StringVar(&opts.StdinFileName, "stdin-filename", "", "File name when reading input from stdin")
+	flags.StringVar(&opts.InputFormat, "input-format", "auto-detect", "What syntax to check 'workflow', 'action' or 'auto-detect'")
 	flags.Usage = func() {
 		fmt.Fprintln(cmd.Stderr, commandUsageHeader)
 		flags.PrintDefaults()
diff --git a/linter.go b/linter.go
index 9894a6dea..4db14a6cc 100644
--- a/linter.go
+++ b/linter.go
@@ -90,6 +90,9 @@ type LinterOptions struct {
 	// function should return the modified rules.
 	// Note that syntax errors may be reported even if this function returns nil or an empty slice.
 	OnRulesCreated func([]Rule) []Rule
+	// InputFormat decides whether directories or files should be linted as workflow files or Action
+	// metadata
+	InputFormat string
 	// More options will come here
 }
 
@@ -107,6 +110,7 @@ type Linter struct {
 	errFmt         *ErrorFormatter
 	cwd            string
 	onRulesCreated func([]Rule) []Rule
+	inputFormat    InputFormat
 }
 
 // NewLinter creates a new Linter instance.
@@ -171,6 +175,19 @@ func NewLinter(out io.Writer, opts *LinterOptions) (*Linter, error) {
 			cwd = d
 		}
 	}
+	var inputFormat InputFormat
+	switch opts.InputFormat {
+	case "workflow":
+		inputFormat = FileWorkflow
+	case "action":
+		inputFormat = FileAction
+	case "":
+		fallthrough
+	case "auto-detect":
+		inputFormat = FileAutoDetect
+	default:
+		return nil, fmt.Errorf("unknown file syntax choose 'workflow', 'action' or 'auto-detect'")
+	}
 
 	return &Linter{
 		NewProjects(),
@@ -185,6 +202,7 @@ func NewLinter(out io.Writer, opts *LinterOptions) (*Linter, error) {
 		formatter,
 		cwd,
 		opts.OnRulesCreated,
+		inputFormat,
 	}, nil
 }
 
@@ -237,11 +255,13 @@ func (l *Linter) GenerateDefaultConfig(dir string) error {
 	return nil
 }
 
-// LintRepository lints YAML workflow files and outputs the errors to given writer. It finds the nearest
-// `.github/workflows` directory based on `dir` and applies lint rules to all YAML workflow files
-// under the directory.
+// LintRepository lints YAML workflow and action files and outputs the errors to given writer.
+// It finds the nearest `.github/workflows` directory based on `dir` and applies lint rules to
+// all YAML workflow files under the directory.
+// Action metadata files are searched for in all other directories of the repository.
+// Note, the InputFormat option can be used to filter this behavior.
 func (l *Linter) LintRepository(dir string) ([]*Error, error) {
-	l.log("Linting all workflow files in repository:", dir)
+	l.log("Linting all", inputFormatString(l.inputFormat), "files in repository:", dir)
 
 	p, err := l.projects.At(dir)
 	if err != nil {
@@ -252,13 +272,37 @@ func (l *Linter) LintRepository(dir string) ([]*Error, error) {
 	}
 
 	l.log("Detected project:", p.RootDir())
-	wd := p.WorkflowsDir()
-	return l.LintDir(wd, p)
+	var parentDir string
+	if l.inputFormat == FileWorkflow {
+		parentDir = p.WorkflowsDir()
+	} else {
+		parentDir = p.RootDir()
+	}
+	return l.LintDir(parentDir, p)
 }
 
-// LintDir lints all YAML workflow files in the given directory recursively.
+// LintDirInRepository lints YAML workflow or actions files and outputs the errors to given writer.
+// It finds the projected based on the nearest `.github/workflows` directory based on `dir`.
+// However, only files within `dir` are linted.
+func (l *Linter) LintDirInRepository(dir string) ([]*Error, error) {
+	l.log("Linting all", inputFormatString(l.inputFormat), "files in repository:", dir)
+
+	p, err := l.projects.At(dir)
+	if err != nil {
+		return nil, err
+	}
+	if p == nil {
+		return nil, fmt.Errorf("no project was found in any parent directories of %q. check workflows directory is put correctly in your Git repository", dir)
+	}
+
+	l.log("Detected project:", p.RootDir())
+	return l.LintDir(dir, p)
+}
+
+// LintDir lints all YAML files in the given directory recursively.
 func (l *Linter) LintDir(dir string, project *Project) ([]*Error, error) {
 	files := []string{}
+	workflow_dir := project.WorkflowsDir()
 	if err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
 			return err
@@ -266,7 +310,19 @@ func (l *Linter) LintDir(dir string, project *Project) ([]*Error, error) {
 		if info.IsDir() {
 			return nil
 		}
-		if strings.HasSuffix(path, ".yml") || strings.HasSuffix(path, ".yaml") {
+		includeAnyYaml := false
+		switch l.inputFormat {
+		case FileAction:
+			includeAnyYaml = false
+		case FileWorkflow:
+			includeAnyYaml = true
+		case FileAutoDetect:
+			includeAnyYaml = strings.HasPrefix(path, workflow_dir)
+		}
+		if !includeAnyYaml && (strings.HasSuffix(path, "action.yml") || strings.HasSuffix(path, "action.yaml")) {
+			files = append(files, path)
+		}
+		if includeAnyYaml && (strings.HasSuffix(path, ".yml") || strings.HasSuffix(path, ".yaml")) {
 			files = append(files, path)
 		}
 		return nil
@@ -395,7 +451,7 @@ func (l *Linter) LintFiles(filepaths []string, project *Project) ([]*Error, erro
 	return all, nil
 }
 
-// LintFile lints one YAML workflow file and outputs the errors to given writer. The project
+// LintFile lints one YAML file and outputs the errors to given writer. The project
 // parameter can be nil. In the case, the project is detected from the given path.
 func (l *Linter) LintFile(path string, project *Project) ([]*Error, error) {
 	if project == nil {
@@ -482,7 +538,7 @@ func (l *Linter) check(
 		start = time.Now()
 	}
 
-	l.log("Linting", path)
+	l.log("Linting", inputFormatString(l.inputFormat), path)
 	if project != nil {
 		l.log("Using project at", project.RootDir())
 	}
@@ -500,32 +556,47 @@ func (l *Linter) check(
 		l.debug("No config was found")
 	}
 
-	w, all := Parse(content)
+	w, a, sf, all := ParseFile(path, content, l.inputFormat)
 
 	if l.logLevel >= LogLevelVerbose {
 		elapsed := time.Since(start)
-		l.log("Found", len(all), "parse errors in", elapsed.Milliseconds(), "ms for", path)
+		l.log("Found", len(all), "parse errors in", elapsed.Milliseconds(), "ms for", inputFormatString(sf), path)
 	}
 
-	if w != nil {
+	if w != nil || a != nil {
 		dbg := l.debugWriter()
 
-		rules := []Rule{
-			NewRuleMatrix(),
-			NewRuleCredentials(),
-			NewRuleShellName(),
-			NewRuleRunnerLabel(),
-			NewRuleEvents(),
-			NewRuleJobNeeds(),
-			NewRuleAction(localActions),
-			NewRuleEnvVar(),
-			NewRuleID(),
-			NewRuleGlob(),
-			NewRulePermissions(),
-			NewRuleWorkflowCall(path, localReusableWorkflows),
-			NewRuleExpression(localActions, localReusableWorkflows),
-			NewRuleDeprecatedCommands(),
-			NewRuleIfCond(),
+		var rules []Rule
+		if w != nil {
+			rules = []Rule{
+				NewRuleMatrix(),
+				NewRuleCredentials(),
+				NewRuleShellName(),
+				NewRuleRunnerLabel(),
+				NewRuleEvents(),
+				NewRuleJobNeeds(),
+				NewRuleAction(localActions),
+				NewRuleEnvVar(),
+				NewRuleID(),
+				NewRuleGlob(),
+				NewRulePermissions(),
+				NewRuleWorkflowCall(path, localReusableWorkflows),
+				NewRuleExpression(localActions, localReusableWorkflows),
+				NewRuleDeprecatedCommands(),
+				NewRuleIfCond(),
+			}
+		} else {
+			rules = []Rule{
+				NewRuleBranding(),
+				NewRuleShellName(),
+				NewRuleAction(localActions),
+				NewRuleEnvVar(),
+				NewRuleID(),
+				NewRuleWorkflowCall(path, localReusableWorkflows),
+				NewRuleExpression(localActions, localReusableWorkflows),
+				NewRuleDeprecatedCommands(),
+				NewRuleIfCond(),
+			}
 		}
 		if l.shellcheck != "" {
 			r, err := NewRuleShellcheck(l.shellcheck, proc)
@@ -567,9 +638,17 @@ func (l *Linter) check(
 			}
 		}
 
-		if err := v.Visit(w); err != nil {
-			l.debug("error occurred while visiting workflow syntax tree: %v", err)
-			return nil, err
+		if w != nil {
+			if err := v.VisitWorkflow(w); err != nil {
+				l.debug("error occurred while visiting workflow syntax tree: %v", err)
+				return nil, err
+			}
+		}
+		if a != nil {
+			if err := v.VisitAction(a); err != nil {
+				l.debug("error occurred while visiting workflow syntax tree: %v", err)
+				return nil, err
+			}
 		}
 
 		for _, rule := range rules {
@@ -607,7 +686,7 @@ func (l *Linter) check(
 
 	if l.logLevel >= LogLevelVerbose {
 		elapsed := time.Since(start)
-		l.log("Found total", len(all), "errors in", elapsed.Milliseconds(), "ms for", path)
+		l.log("Found total", len(all), "errors in", elapsed.Milliseconds(), "ms for", inputFormatString(sf), path)
 	}
 
 	return all, nil
diff --git a/linter_test.go b/linter_test.go
index ac990053f..cad238c3c 100644
--- a/linter_test.go
+++ b/linter_test.go
@@ -17,7 +17,7 @@ import (
 	"golang.org/x/sys/execabs"
 )
 
-func TestLinterLintOK(t *testing.T) {
+func TestLinterLintWorkflowOK(t *testing.T) {
 	dir := filepath.Join("testdata", "ok")
 
 	es, err := os.ReadDir(dir)
@@ -73,7 +73,52 @@ func TestLinterLintOK(t *testing.T) {
 	}
 }
 
-func testFindAllWorkflowsInDir(subdir string) (string, []string, error) {
+func TestLinterLintActionOK(t *testing.T) {
+	dir, fs, err := testFindAllYamlInDir("actions/ok")
+
+	if err != nil {
+		panic(err)
+	}
+
+	proj := &Project{root: dir}
+	shellcheck, err := execabs.LookPath("shellcheck")
+	if err != nil {
+		t.Skip("skipped because \"shellcheck\" command does not exist in system")
+	}
+
+	pyflakes, err := execabs.LookPath("pyflakes")
+	if err != nil {
+		t.Skip("skipped because \"pyflakes\" command does not exist in system")
+	}
+
+	for _, f := range fs {
+		t.Run(filepath.Base(f), func(t *testing.T) {
+			opts := LinterOptions{
+				Shellcheck:  shellcheck,
+				Pyflakes:    pyflakes,
+				InputFormat: "action",
+			}
+
+			linter, err := NewLinter(io.Discard, &opts)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			config := Config{}
+			linter.defaultConfig = &config
+
+			errs, err := linter.LintFile(f, proj)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if len(errs) > 0 {
+				t.Fatal(errs)
+			}
+		})
+	}
+}
+
+func testFindAllYamlInDir(subdir string) (string, []string, error) {
 	dir := filepath.Join("testdata", subdir)
 
 	entries, err := os.ReadDir(dir)
@@ -137,9 +182,9 @@ func checkErrors(t *testing.T, outfile string, errs []*Error) {
 	}
 }
 
-func TestLinterLintError(t *testing.T) {
+func TestLinterLintWorkflowError(t *testing.T) {
 	for _, subdir := range []string{"examples", "err"} {
-		dir, infiles, err := testFindAllWorkflowsInDir(subdir)
+		dir, infiles, err := testFindAllYamlInDir(subdir)
 		if err != nil {
 			panic(err)
 		}
@@ -199,6 +244,66 @@ func TestLinterLintError(t *testing.T) {
 	}
 }
 
+func TestLinterLintActionError(t *testing.T) {
+	dir, infiles, err := testFindAllYamlInDir("actions/err")
+	if err != nil {
+		panic(err)
+	}
+
+	proj := &Project{root: dir}
+
+	shellcheck := ""
+	if p, err := execabs.LookPath("shellcheck"); err == nil {
+		shellcheck = p
+	}
+
+	pyflakes := ""
+	if p, err := execabs.LookPath("pyflakes"); err == nil {
+		pyflakes = p
+	}
+
+	for _, infile := range infiles {
+		base := strings.TrimSuffix(infile, filepath.Ext(infile))
+		testName := filepath.Base(base)
+		t.Run(testName, func(t *testing.T) {
+			b, err := os.ReadFile(infile)
+			if err != nil {
+				panic(err)
+			}
+
+			o := LinterOptions{InputFormat: "action"}
+
+			if strings.Contains(testName, "shellcheck") {
+				if shellcheck == "" {
+					t.Skip("skipped because \"shellcheck\" command does not exist in system")
+				}
+				o.Shellcheck = shellcheck
+			}
+
+			if strings.Contains(testName, "pyflakes") {
+				if pyflakes == "" {
+					t.Skip("skipped because \"pyflakes\" command does not exist in system")
+				}
+				o.Pyflakes = pyflakes
+			}
+
+			l, err := NewLinter(io.Discard, &o)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			l.defaultConfig = &Config{}
+
+			errs, err := l.Lint("test.yaml", b, proj)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			checkErrors(t, base+".out", errs)
+		})
+	}
+}
+
 func TestLintFindProjectFromPath(t *testing.T) {
 	d := filepath.Join("testdata", "find_project")
 	f := filepath.Join(d, ".github", "workflows", "test.yaml")
@@ -256,7 +361,7 @@ func TestLinterLintProject(t *testing.T) {
 			opts := LinterOptions{
 				WorkingDir: repo,
 			}
-			cfg := filepath.Join(repo, "actionlint.yaml")
+			cfg := filepath.Join(repo, ".github", "actionlint.yaml")
 			if _, err := os.Stat(cfg); err == nil {
 				opts.ConfigFile = cfg
 			}
@@ -266,7 +371,7 @@ func TestLinterLintProject(t *testing.T) {
 			}
 
 			proj := &Project{root: repo}
-			errs, err := linter.LintDir(filepath.Join(repo, "workflows"), proj)
+			errs, err := linter.LintDir(filepath.Join(repo, ".github", "workflows"), proj)
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -706,7 +811,7 @@ func BenchmarkLintWorkflowContent(b *testing.B) {
 }
 
 func BenchmarkExamplesLintFiles(b *testing.B) {
-	dir, files, err := testFindAllWorkflowsInDir("examples")
+	dir, files, err := testFindAllYamlInDir("examples")
 	if err != nil {
 		panic(err)
 	}
diff --git a/parse.go b/parse.go
index 989b02f0e..03aa73628 100644
--- a/parse.go
+++ b/parse.go
@@ -41,7 +41,7 @@ func newString(n *yaml.Node) *String {
 	return &String{n.Value, quoted, posAt(n)}
 }
 
-type workflowKeyVal struct {
+type yamlKeyValue struct {
 	// id is used for comparing keys. When the key is case insensitive, this field is in lower case.
 	id  string
 	key *String
@@ -247,7 +247,7 @@ func (p *parser) parseFloat(n *yaml.Node) *Float {
 	}
 }
 
-func (p *parser) parseMapping(what string, n *yaml.Node, allowEmpty, caseSensitive bool) []workflowKeyVal {
+func (p *parser) parseMapping(what string, n *yaml.Node, allowEmpty, caseSensitive bool) []yamlKeyValue {
 	isNull := isNull(n)
 
 	if !isNull && n.Kind != yaml.MappingNode {
@@ -262,7 +262,7 @@ func (p *parser) parseMapping(what string, n *yaml.Node, allowEmpty, caseSensiti
 
 	l := len(n.Content) / 2
 	keys := make(map[string]*Pos, l)
-	m := make([]workflowKeyVal, 0, l)
+	m := make([]yamlKeyValue, 0, l)
 	for i := 0; i < len(n.Content); i += 2 {
 		k := p.parseString(n.Content[i], false)
 		if k == nil {
@@ -287,7 +287,7 @@ func (p *parser) parseMapping(what string, n *yaml.Node, allowEmpty, caseSensiti
 			p.errorfAt(k.Pos, "key %q is duplicated in %s. previously defined at %s%s", k.Value, what, pos.String(), note)
 			continue
 		}
-		m = append(m, workflowKeyVal{id, k, n.Content[i+1]})
+		m = append(m, yamlKeyValue{id, k, n.Content[i+1]})
 		keys[id] = k.Pos
 	}
 
@@ -298,7 +298,7 @@ func (p *parser) parseMapping(what string, n *yaml.Node, allowEmpty, caseSensiti
 	return m
 }
 
-func (p *parser) parseSectionMapping(sec string, n *yaml.Node, allowEmpty, caseSensitive bool) []workflowKeyVal {
+func (p *parser) parseSectionMapping(sec string, n *yaml.Node, allowEmpty, caseSensitive bool) []yamlKeyValue {
 	return p.parseMapping(fmt.Sprintf("%q section", sec), n, allowEmpty, caseSensitive)
 }
 
@@ -980,7 +980,7 @@ func (p *parser) parseTimeoutMinutes(n *yaml.Node) *Float {
 }
 
 // https://docs.github.com/en/actions/learn-github-actions/workflow-syntax-for-github-actions#jobsjob_idsteps
-func (p *parser) parseStep(n *yaml.Node) *Step {
+func (p *parser) parseStep(n *yaml.Node, requireShell bool) *Step {
 	ret := &Step{Pos: posAt(n)}
 	var workDir *String
 
@@ -1013,7 +1013,7 @@ func (p *parser) parseStep(n *yaml.Node) *Step {
 			} else {
 				// kv.key == "with"
 				with := p.parseSectionMapping("with", kv.val, false, false)
-				exec.Inputs = make(map[string]*Input, len(with))
+				exec.Inputs = make(map[string]*StepInput, len(with))
 				for _, input := range with {
 					switch input.id {
 					case "entrypoint":
@@ -1023,7 +1023,7 @@ func (p *parser) parseStep(n *yaml.Node) *Step {
 						// https://docs.github.com/en/actions/learn-github-actions/workflow-syntax-for-github-actions#jobsjob_idstepswithargs
 						exec.Args = p.parseString(input.val, true)
 					default:
-						exec.Inputs[input.id] = &Input{input.key, p.parseString(input.val, true)}
+						exec.Inputs[input.id] = &StepInput{input.key, p.parseString(input.val, true)}
 					}
 				}
 			}
@@ -1081,6 +1081,9 @@ func (p *parser) parseStep(n *yaml.Node) *Step {
 		if e.Run == nil {
 			p.error(n, "\"run\" is required to run script in step")
 		}
+		if e.Shell == nil && requireShell {
+			p.error(n, "\"shell\" is required to run script in step as part of composite actions")
+		}
 	default:
 		p.error(n, "step must run script with \"run\" section or run action with \"uses\" section")
 	}
@@ -1089,7 +1092,7 @@ func (p *parser) parseStep(n *yaml.Node) *Step {
 }
 
 // https://docs.github.com/en/actions/learn-github-actions/workflow-syntax-for-github-actions#jobsjob_idsteps
-func (p *parser) parseSteps(n *yaml.Node) []*Step {
+func (p *parser) parseSteps(n *yaml.Node, requireShell bool) []*Step {
 	if ok := p.checkSequence("steps", n, false); !ok {
 		return nil
 	}
@@ -1097,7 +1100,7 @@ func (p *parser) parseSteps(n *yaml.Node) []*Step {
 	ret := make([]*Step, 0, len(n.Content))
 
 	for _, c := range n.Content {
-		if s := p.parseStep(c); s != nil {
+		if s := p.parseStep(c, requireShell); s != nil {
 			ret = append(ret, s)
 		}
 	}
@@ -1191,7 +1194,7 @@ func (p *parser) parseJob(id *String, n *yaml.Node) *Job {
 		case "if":
 			ret.If = p.parseString(v, false)
 		case "steps":
-			ret.Steps = p.parseSteps(v)
+			ret.Steps = p.parseSteps(v, false)
 			stepsOnlyKey = k
 		case "timeout-minutes":
 			ret.TimeoutMinutes = p.parseTimeoutMinutes(v)
@@ -1314,7 +1317,7 @@ func (p *parser) parseJobs(n *yaml.Node) map[string]*Job {
 }
 
 // https://docs.github.com/en/actions/learn-github-actions/workflow-syntax-for-github-actions
-func (p *parser) parse(n *yaml.Node) *Workflow {
+func (p *parser) parseWorkflow(n *yaml.Node) *Workflow {
 	w := &Workflow{}
 
 	if n.Line == 0 {
@@ -1372,6 +1375,310 @@ func (p *parser) parse(n *yaml.Node) *Workflow {
 	return w
 }
 
+// https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#inputsinput_id
+func (p *parser) parseActionInput(id *String, n *yaml.Node) *ActionInput {
+	ret := &ActionInput{Pos: posAt(n)}
+
+	for _, kv := range p.parseMapping(fmt.Sprintf("%q input", id.Value), n, false, true) {
+		switch kv.id {
+		case "description":
+			ret.Description = p.parseString(kv.val, false)
+		case "required":
+			ret.Required = p.parseBool(kv.val)
+		case "default":
+			ret.Default = p.parseString(kv.val, true)
+		case "deprecationMessage":
+			ret.DeprecationMessage = p.parseString(kv.val, false)
+		default:
+			p.unexpectedKey(kv.key, "input", []string{
+				"description",
+				"required",
+				"default",
+				"deprecationMessage",
+			})
+		}
+	}
+
+	if ret.Description == nil {
+		p.errorf(n, "\"description\" property is missing in specification of input %q", id.Value)
+	}
+
+	return ret
+}
+
+func (p *parser) parseActionInputs(pos *Pos, n *yaml.Node) map[string]*ActionInput {
+	inputs := p.parseSectionMapping("inputs", n, false, false)
+	ret := make(map[string]*ActionInput, len(inputs))
+	for _, kv := range inputs {
+		ret[kv.id] = p.parseActionInput(kv.key, kv.val)
+	}
+
+	return ret
+}
+
+// https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#outputs-for-docker-container-and-javascript-actions
+// https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#outputs-for-composite-actions
+func (p *parser) parseActionOutput(id *String, n *yaml.Node) *ActionOutput {
+	ret := &ActionOutput{Pos: posAt(n)}
+
+	for _, kv := range p.parseMapping(fmt.Sprintf("%q outputs", id.Value), n, false, true) {
+		switch kv.id {
+		case "description":
+			ret.Description = p.parseString(kv.val, false)
+		case "value":
+			ret.Value = p.parseString(kv.val, false)
+		default:
+			p.unexpectedKey(kv.key, "output", []string{
+				"description",
+				"value",
+			})
+		}
+	}
+
+	return ret
+}
+
+func (p *parser) parseActionOutputs(pos *Pos, n *yaml.Node) map[string]*ActionOutput {
+	outputs := p.parseSectionMapping("outputs", n, false, false)
+	ret := make(map[string]*ActionOutput, len(outputs))
+	for _, kv := range outputs {
+		ret[kv.id] = p.parseActionOutput(kv.key, kv.val)
+	}
+
+	return ret
+}
+
+func (p *parser) parseActionRuns(n *yaml.Node) ActionRuns {
+	var r ActionRuns
+	hadUsingKey := false
+	for _, kv := range p.parseMapping("runs", n, false, true) {
+		switch kv.id {
+		case "using":
+			using := p.parseString(kv.val, false)
+			hadUsingKey = true
+			switch {
+			case strings.HasPrefix(using.Value, "node"):
+				if r == nil {
+					r = &JavaScriptRuns{Using: using}
+				} else if na, ok := r.(*JavaScriptRuns); ok {
+					na.Using = using
+				} else {
+					p.errorAt(kv.key.Pos, "this action declares it uses javascript but has foreign keys")
+				}
+			case using.Value == "docker":
+				if r == nil {
+					r = &DockerContainerRuns{}
+				} else if r.Kind() != ActionKindDockerContainer {
+					p.errorAt(kv.key.Pos, "this action declares it uses docker container but has foreign keys")
+				}
+			case using.Value == "composite":
+				if r == nil {
+					r = &CompositeRuns{}
+				} else if r.Kind() != ActionKindComposite {
+					p.errorAt(kv.key.Pos, "this action declares it is a composite action but has foreign keys")
+				}
+			default:
+				p.errorf(kv.val, "unknown action type %s, (only javascript, docker and composite are supported)", using.Value)
+				return nil
+			}
+		case "steps":
+			var def *CompositeRuns
+			if r == nil {
+				def = &CompositeRuns{}
+				r = def
+			} else if ca, ok := r.(*CompositeRuns); ok {
+				def = ca
+			} else {
+				p.errorfAt(kv.key.Pos, "this action defines parameter %s for composite actions, but is something else", kv.id)
+				continue
+			}
+			def.Steps = p.parseSteps(kv.val, true)
+		case "main", "pre", "pre-if", "post", "post-if":
+			var def *JavaScriptRuns
+			if r == nil {
+				def = &JavaScriptRuns{}
+				r = def
+			} else if na, ok := r.(*JavaScriptRuns); ok {
+				def = na
+			} else {
+				p.errorfAt(kv.key.Pos, "this action defines parameter %s for javascript actions, but is something else", kv.id)
+				continue
+			}
+			switch kv.id {
+			case "main":
+				def.Main = p.parseString(kv.val, false)
+			case "pre":
+				def.Pre = p.parseString(kv.val, false)
+			case "pre-if":
+				def.PreIf = p.parseString(kv.val, false)
+			case "post":
+				def.Post = p.parseString(kv.val, false)
+			case "post-if":
+				def.PostIf = p.parseString(kv.val, false)
+			}
+		case "image", "entrypoint", "args", "env", "pre-entrypoint", "post-entrypoint":
+			var def *DockerContainerRuns
+			if r == nil {
+				def = &DockerContainerRuns{}
+				r = def
+			} else if da, ok := r.(*DockerContainerRuns); ok {
+				def = da
+			} else {
+				p.errorfAt(kv.key.Pos, "this action defines parameter %s for javascript actions, but is something else", kv.id)
+				continue
+			}
+			switch kv.id {
+			case "image":
+				def.Image = p.parseString(kv.val, false)
+			case "args":
+				def.Args = p.parseStringSequence("args", kv.val, true, false)
+			case "env":
+				def.Env = p.parseEnv(kv.val)
+			case "pre-entrypoint":
+				def.PreEntrypoint = p.parseString(kv.val, false)
+			case "entrypoint":
+				def.Entrypoint = p.parseString(kv.val, false)
+			case "post-entrypoint":
+				def.PostEntrypoint = p.parseString(kv.val, false)
+			}
+		default:
+			p.unexpectedKey(kv.key, "runs", []string{
+				"using",
+				"main",
+				"pre",
+				"pre-if",
+				"post",
+				"post-if",
+				"image",
+				"args",
+				"env",
+				"pre-entrypoint",
+				"entrypoint",
+				"post-entrypoint",
+				"steps",
+			})
+		}
+	}
+
+	if !hadUsingKey {
+		p.error(n, "\"using\" is required to define what to execute")
+		return r
+	}
+
+	switch a := r.(type) {
+	case *JavaScriptRuns:
+		if a.Main == nil {
+			p.error(n, "\"main\" is required for a javascript action")
+		}
+	case *DockerContainerRuns:
+		if a.Image == nil {
+			p.error(n, "\"image\" is required for a docker container action")
+		}
+	case *CompositeRuns:
+		if a.Steps == nil {
+			p.error(n, "\"steps\" is required for a composite action")
+		}
+	}
+	return r
+}
+
+func (p *parser) parseBranding(n *yaml.Node) *Branding {
+	b := Branding{}
+	for _, kv := range p.parseMapping("branding", n, false, false) {
+		switch kv.id {
+		case "color":
+			b.Color = p.parseString(kv.val, false)
+		case "icon":
+			b.Icon = p.parseString(kv.val, false)
+		default:
+			p.unexpectedKey(kv.key, "branding", []string{
+				"color",
+				"icon",
+			})
+		}
+	}
+
+	if b.Icon == nil {
+		p.error(n, "\"icon\" is required for branding information")
+	}
+	if b.Color == nil {
+		p.error(n, "\"color\" is required for branding information")
+	}
+	return &b
+}
+
+// https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions
+func (p *parser) parseAction(n *yaml.Node) *Action {
+	a := &Action{}
+	if n.Line == 0 {
+		n.Line = 1
+	}
+	if n.Column == 0 {
+		n.Column = 1
+	}
+
+	if len(n.Content) == 0 {
+		p.error(n, "action is empty")
+		return a
+	}
+
+	hasRunsBlock := false
+
+	for _, kv := range p.parseMapping("action", n.Content[0], false, true) {
+		k, v := kv.key, kv.val
+		switch kv.id {
+		case "name":
+			a.Name = p.parseString(v, true)
+		case "author":
+			a.Author = p.parseString(v, true)
+		case "description":
+			a.Description = p.parseString(v, true)
+		case "inputs":
+			a.Inputs = p.parseActionInputs(k.Pos, v)
+		case "outputs":
+			a.Outputs = p.parseActionOutputs(k.Pos, v)
+		case "runs":
+			a.Runs = p.parseActionRuns(v)
+			hasRunsBlock = true // even if parseActionRuns is nil, it is still had a runs block
+		case "branding":
+			a.Branding = p.parseBranding(v)
+		default:
+			p.unexpectedKey(k, "action", []string{
+				"name",
+				"author",
+				"description",
+				"inputs",
+				"outputs",
+				"runs",
+				"branding",
+			})
+		}
+	}
+
+	if a.Name == nil {
+		p.error(n, "\"name\" property is missing in action metadata")
+	}
+	if a.Description == nil {
+		p.error(n, "\"description\" property is missing in action metadata")
+	}
+	if !hasRunsBlock {
+		p.error(n, "\"runs\" section is missing in action metadata")
+	}
+	if a.Runs != nil {
+		requireValue := a.Runs.Kind() == ActionKindComposite
+		for _, o := range a.Outputs {
+			if o.Value == nil && requireValue {
+				p.errorAt(o.Pos, "output value is required for composite actions")
+			}
+			if o.Value != nil && !requireValue {
+				p.errorAt(o.Pos, "output value is only allowed for composite actions")
+			}
+		}
+	}
+
+	return a
+}
+
 // func dumpYAML(n *yaml.Node, level int) {
 // 	fmt.Printf("%s%s (%s, %d,%d): %q\n", strings.Repeat(". ", level), nodeKindName(n.Kind), n.Tag, n.Line, n.Column, n.Value)
 // 	for _, c := range n.Content {
@@ -1402,21 +1709,86 @@ func handleYAMLError(err error) []*Error {
 	return []*Error{yamlErr(err.Error())}
 }
 
-// Parse parses given source as byte sequence into workflow syntax tree. It returns all errors
-// detected while parsing the input. It means that detecting one error does not stop parsing. Even
-// if one or more errors are detected, parser will try to continue parsing and finding more errors.
+// InputFormat is kind of how input files should be treated (as workflow file, action file or either of them).
+type InputFormat uint8
+
+const (
+	// FileWorkflow ensures the file is parsed as Actions workflow
+	FileWorkflow InputFormat = iota
+	// FileAction ensures the file is parsed as Action metadata file
+	FileAction
+	// FileAutoDetect will select between workflow and action metadata file based on filename and file content.
+	FileAutoDetect
+)
+
+func inputFormatString(inputFormat InputFormat) string {
+	switch inputFormat {
+	case FileWorkflow:
+		return "workflow"
+	case FileAction:
+		return "action"
+	case FileAutoDetect:
+		return "workflow or action"
+	}
+	return "unknown"
+}
+
+func selectFormat(filename string, node *yaml.Node, format InputFormat) InputFormat {
+	if format != FileAutoDetect { // Format is already enforced
+		return format
+	}
+	if strings.Contains(filename, ".github/workflows/") {
+		// println("Detect", filename, "as workflow file based (due to its directory)")
+		return FileWorkflow
+	}
+	if strings.HasSuffix(filename, "/action.yaml") || strings.HasSuffix(filename, "/action.yml") {
+		// println("Detect", filename, "as action filename based (due to its filename)")
+		return FileAction
+	}
+
+	// selecting Action if `runs` element is present Workflow otherwise:
+	if isNull(node) || len(node.Content) == 0 || node.Content[0].Kind != yaml.MappingNode {
+		// println("Defaulted", filename, "as workflow (file is not a yaml mapping)", nodeKindName(node.Kind))
+		return FileWorkflow
+	}
+
+	for i := 0; i < len(node.Content[0].Content); i += 2 {
+		if node.Content[0].Content[i].Kind == yaml.ScalarNode && node.Content[0].Content[i].Value == "runs" {
+			// println("Detected", filename, "as action workflow (it has a 'runs' key)")
+			return FileAction
+		}
+	}
+	return FileWorkflow
+}
+
+// Parse is an alias for ParseFile with default values for API stability
 func Parse(b []byte) (*Workflow, []*Error) {
+	w, _, _, errs := ParseFile("<stdin>", b, FileWorkflow)
+	return w, errs
+}
+
+// ParseFile parses given source as byte sequence into action or workflow syntax tree. It returns
+// all errors detected while parsing the input. It means that detecting one error does not stop parsing.
+// Even if one or more errors are detected, parser will try to continue parsing and finding more errors.
+func ParseFile(filename string, b []byte, format InputFormat) (*Workflow, *Action, InputFormat, []*Error) {
 	var n yaml.Node
+	var a *Action
+	var w *Workflow
 
 	if err := yaml.Unmarshal(b, &n); err != nil {
-		return nil, handleYAMLError(err)
+		return nil, nil, format, handleYAMLError(err)
 	}
 
 	// Uncomment for checking YAML tree
 	// dumpYAML(&n, 0)
 
 	p := &parser{}
-	w := p.parse(&n)
+	sf := selectFormat(filename, &n, format)
+	if sf == FileWorkflow {
+		w = p.parseWorkflow(&n)
+	} else {
+		a = p.parseAction(&n)
+	}
 
-	return w, p.errors
+	return w, a, sf, p.errors
 }
diff --git a/parse_test.go b/parse_test.go
new file mode 100644
index 000000000..0702036ce
--- /dev/null
+++ b/parse_test.go
@@ -0,0 +1,54 @@
+package actionlint
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestDetectFilesAsWorkflow(t *testing.T) {
+	dir := filepath.Join("testdata", "detect_format", "workflows")
+	if err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.IsDir() {
+			return nil
+		}
+		b, err := os.ReadFile(path)
+		if err != nil {
+			panic(err)
+		}
+		_, _, sf, _ := ParseFile(path, b, FileAutoDetect)
+		if sf != FileWorkflow {
+			t.Errorf("file %s is not detected as workflow", path)
+		}
+		return nil
+	}); err != nil {
+		panic(fmt.Errorf("could not read files in %q: %w", dir, err))
+	}
+}
+
+func TestDetectFilesAsAction(t *testing.T) {
+	dir := filepath.Join("testdata", "detect_format", "actions")
+	if err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.IsDir() {
+			return nil
+		}
+		b, err := os.ReadFile(path)
+		if err != nil {
+			panic(err)
+		}
+		_, _, sf, _ := ParseFile(path, b, FileAutoDetect)
+		if sf != FileAction {
+			t.Errorf("file %s is not detected as action", path)
+		}
+		return nil
+	}); err != nil {
+		panic(fmt.Errorf("could not read files in %q: %w", dir, err))
+	}
+}
diff --git a/pass.go b/pass.go
index e626fe221..2e8da3683 100644
--- a/pass.go
+++ b/pass.go
@@ -18,6 +18,11 @@ type Pass interface {
 	VisitWorkflowPre(node *Workflow) error
 	// VisitWorkflowPost is callback when visiting Workflow node after visiting its children. It returns internal error when it cannot continue the process
 	VisitWorkflowPost(node *Workflow) error
+
+	// VisitActionPre is callback when visiting Action node before visiting its children. It returns internal error when it cannot continue the process
+	VisitActionPre(node *Action) error
+	// VisitActionPost is callback when visiting Action node after visiting its children. It returns internal error when it cannot continue the process
+	VisitActionPost(node *Action) error
 }
 
 // Visitor visits syntax tree from root in depth-first order
@@ -46,8 +51,13 @@ func (v *Visitor) reportElapsedTime(what string, start time.Time) {
 	fmt.Fprintf(v.dbg, "[Visitor] %s took %vms\n", what, time.Since(start).Milliseconds())
 }
 
-// Visit visits given syntax tree in depth-first order
+// Visit is an alias for VisitWorkflow for API stability
 func (v *Visitor) Visit(n *Workflow) error {
+	return v.VisitWorkflow(n)
+}
+
+// VisitWorkflow visits given syntax tree in depth-first order
+func (v *Visitor) VisitWorkflow(n *Workflow) error {
 	var t time.Time
 	if v.dbg != nil {
 		t = time.Now()
@@ -88,6 +98,50 @@ func (v *Visitor) Visit(n *Workflow) error {
 	return nil
 }
 
+// VisitAction visits given syntax tree in depth-first order
+func (v *Visitor) VisitAction(n *Action) error {
+	var t time.Time
+	if v.dbg != nil {
+		t = time.Now()
+	}
+
+	for _, p := range v.passes {
+		if err := p.VisitActionPre(n); err != nil {
+			return err
+		}
+	}
+
+	if v.dbg != nil {
+		v.reportElapsedTime("VisitActionPre", t)
+		t = time.Now()
+	}
+
+	if c, ok := n.Runs.(*CompositeRuns); ok {
+		for _, s := range c.Steps {
+			if err := v.visitStep(s); err != nil {
+				return err
+			}
+		}
+
+		if v.dbg != nil {
+			v.reportElapsedTime(fmt.Sprintf("Visiting %d steps of action %q", len(c.Steps), n.Name.Value), t)
+			t = time.Now()
+		}
+	}
+
+	for _, p := range v.passes {
+		if err := p.VisitActionPost(n); err != nil {
+			return err
+		}
+	}
+
+	if v.dbg != nil {
+		v.reportElapsedTime("VisitActionPost", t)
+	}
+
+	return nil
+}
+
 func (v *Visitor) visitJob(n *Job) error {
 	var t time.Time
 	if v.dbg != nil {
diff --git a/playground/index.html b/playground/index.html
index 7c8a2181e..d2963d860 100644
--- a/playground/index.html
+++ b/playground/index.html
@@ -24,7 +24,7 @@
     <nav id="header-bar" class="navbar" role="navigation" aria-label="header navigation bar">
       <header class="header">
         <h1 class="title"><a id="logo" rel="noopener" href="https://github.com/rhysd/actionlint"><i class="devicon-github-original"></i></a> actionlint playground</h1>
-        <h2 class="subtitle">Static checker for GitHub Actions workflow files</h2>
+        <h2 class="subtitle">Static checker for GitHub Actions workflow and action metadata files</h2>
       </header>
       <div class="navbar-end">
         <div class="control">
@@ -42,7 +42,19 @@ <h2 class="subtitle">Static checker for GitHub Actions workflow files</h2>
 
     </nav>
     <main>
-      <div id="editor" class="split-pane"></div>
+      <div class="split-pane">
+        <div class="tabs is-toggle type-toggle">
+          <ul>
+            <li class="is-active" id="toggle-workflow">
+              <a>Wokflow</a>
+            </li>
+            <li id="toggle-action">
+              <a>Action</a>
+            </li>
+          </ul>
+        </div>
+        <div id="editor"></div>
+      </div>
       <div class="split-pane">
         <div id="loading" class="notification sticky has-text-centered is-size-5">Loading WebAssembly binary...</div>
         <table id="lint-result" class="table sticky is-hoverable">
diff --git a/playground/index.ts b/playground/index.ts
index 25a3b0c55..04d6810e9 100644
--- a/playground/index.ts
+++ b/playground/index.ts
@@ -18,6 +18,13 @@
     const checkUrlButton = getElementById('check-url-btn');
     const checkUrlInput = getElementById('check-url-input') as HTMLInputElement;
     const permalinkButton = getElementById('permalink-btn');
+    const toggleWorkflow = getElementById('toggle-workflow');
+    const toggleAction = getElementById('toggle-action');
+
+    function getCurrentType() {
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        return document.querySelector('.is-active')!.id === 'toggle-workflow' ? 'workflow' : 'action';
+    }
 
     async function getRemoteSource(url: string): Promise<string> {
         function getUrlToFetch(u: string): string {
@@ -52,7 +59,7 @@
         return src.trim();
     }
 
-    async function getDefaultSource(): Promise<string> {
+    async function getDefaultSource(type: 'workflow' | 'action' = 'workflow'): Promise<string> {
         const params = new URLSearchParams(window.location.search);
 
         const s = params.get('s');
@@ -72,7 +79,7 @@
             return new TextDecoder().decode(decompressed);
         }
 
-        const src = `# Paste your workflow YAML to this code editor
+        const workflowSrc = `# Paste your workflow YAML to this code editor
 
 on:
   push:
@@ -98,7 +105,22 @@ jobs:
         if: \${{ github.repository.permissions.admin == true }}
       - run: npm install && npm test`;
 
-        return src;
+        const actionSrc = `# Paste your action YAML to this code editor
+
+name: 'My Action Name'
+description: 'My Action Description'
+inputs:
+    my_input:
+        description: 'My input'
+        required: true
+        default: 3
+    my_other_input:
+        required: true
+runs:
+    using: 'node12'
+    main: 'index.js'`;
+
+        return type === 'workflow' ? workflowSrc : actionSrc;
     }
 
     const editorConfig: CodeMirror.EditorConfiguration = {
@@ -121,33 +143,38 @@ jobs:
     const debounceInterval = isMobile.phone ? 1000 : 300;
     let debounceId: number | null = null;
     let contentChanged = false;
-    editor.on('change', function (_, e) {
-        contentChanged = true;
+
+    function startActionlint(): void {
+        debounceId = null;
 
         if (typeof window.runActionlint !== 'function') {
             showError('Preparing Wasm file is not completed yet. Please wait for a while and try again.');
             return;
         }
 
+        errorMessage.style.display = 'none';
+        successMessage.style.display = 'none';
+        editor.clearGutter('error-marker');
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        window.runActionlint!(editor.getValue(), getCurrentType());
+    }
+
+    function startActionLintDebounced(): void {
         if (debounceId !== null) {
             window.clearTimeout(debounceId);
         }
+        debounceId = window.setTimeout(() => startActionlint(), debounceInterval);
+    }
 
-        function startActionlint(): void {
-            debounceId = null;
-            errorMessage.style.display = 'none';
-            successMessage.style.display = 'none';
-            editor.clearGutter('error-marker');
-            // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-            window.runActionlint!(editor.getValue());
-        }
+    editor.on('change', function (_, e) {
+        contentChanged = true;
 
         if (e.origin === 'paste') {
             startActionlint(); // When pasting some code, apply actionlint instantly
             return;
         }
 
-        debounceId = window.setTimeout(() => startActionlint(), debounceInterval);
+        startActionLintDebounced();
     });
 
     function getSource(): string {
@@ -289,6 +316,26 @@ jobs:
         window.location.hash = b64;
     });
 
+    [toggleWorkflow, toggleAction].forEach(element => {
+        element.addEventListener('click', async event => {
+            event.preventDefault();
+            const target = event.currentTarget as HTMLElement;
+            if (!target.classList.contains('is-active')) {
+                target.classList.add('is-active');
+                // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+                const sibling = (target.nextElementSibling || target.previousElementSibling)!;
+                sibling.classList.remove('is-active');
+
+                if (!contentChanged) {
+                    editor.setValue(await getDefaultSource(target.id === 'toggle-workflow' ? 'workflow' : 'action'));
+                    contentChanged = false;
+                } else {
+                    startActionLintDebounced();
+                }
+            }
+        });
+    });
+
     const go = new Go();
 
     let result;
diff --git a/playground/lib.d.ts b/playground/lib.d.ts
index b6cb37863..dc850e0c3 100644
--- a/playground/lib.d.ts
+++ b/playground/lib.d.ts
@@ -6,7 +6,7 @@ interface ActionlintError {
 }
 
 interface Window {
-    runActionlint?(src: string): void;
+    runActionlint?(src: string, typ: 'workflow' | 'action'): void;
     getYamlSource(): string;
     showError(msg: string): void;
     onCheckCompleted(errs: ActionlintError[]): void;
diff --git a/playground/main.go b/playground/main.go
index 640620f0d..4ee9308f9 100644
--- a/playground/main.go
+++ b/playground/main.go
@@ -26,8 +26,8 @@ func encodeErrorAsMap(err *actionlint.Error) map[string]interface{} {
 	return obj
 }
 
-func lint(source string) interface{} {
-	opts := actionlint.LinterOptions{}
+func lint(source string, typ string) interface{} {
+	opts := actionlint.LinterOptions{InputFormat: typ}
 	linter, err := actionlint.NewLinter(io.Discard, &opts)
 	if err != nil {
 		fail(err, "creating linter instance")
@@ -35,6 +35,7 @@ func lint(source string) interface{} {
 	}
 
 	errs, err := linter.Lint("test.yaml", []byte(source), nil)
+
 	if err != nil {
 		fail(err, "applying lint rules")
 		return nil
@@ -52,12 +53,14 @@ func lint(source string) interface{} {
 
 func runActionlint(_this js.Value, args []js.Value) interface{} {
 	source := args[0].String()
-	return lint(source)
+	typ := args[1].String()
+
+	return lint(source, typ)
 }
 
 func main() {
 	window.Set("runActionlint", js.FuncOf(runActionlint))
 	window.Call("dismissLoading")
-	lint(window.Call("getYamlSource").String()) // Show the first result
+	lint(window.Call("getYamlSource").String(), "workflow") // Show the first result
 	select {}
 }
diff --git a/playground/style.css b/playground/style.css
index 878f8de65..8c56ea571 100644
--- a/playground/style.css
+++ b/playground/style.css
@@ -70,3 +70,12 @@ main {
 footer {
   margin-top: 32px;
 }
+
+.type-toggle {
+  margin-right: 1rem;
+}
+
+.type-toggle li a {
+  padding: calc(.5em - 1px) 1em;
+  height: 2.5em;
+}
diff --git a/playground/test.ts b/playground/test.ts
index 20b67f8cb..6d571f477 100644
--- a/playground/test.ts
+++ b/playground/test.ts
@@ -94,7 +94,7 @@ jobs:
     steps:
       - run: echo 'hi'`;
 
-        window.runActionlint(source);
+        window.runActionlint(source, 'workflow');
         const errors = await results.waitCheckCompleted();
         const json = JSON.stringify(errors);
         assert.equal(errors.length, 1, json);
@@ -120,7 +120,7 @@ jobs:
     steps:
       - run: echo 'hi'`;
 
-        window.runActionlint(source);
+        window.runActionlint(source, 'workflow');
         const errors = await results.waitCheckCompleted();
         const json = JSON.stringify(errors);
         assert.equal(errors.length, 0, json);
diff --git a/rule.go b/rule.go
index ed0e169b1..81ef68185 100644
--- a/rule.go
+++ b/rule.go
@@ -39,6 +39,12 @@ func (r *RuleBase) VisitWorkflowPre(node *Workflow) error { return nil }
 // VisitWorkflowPost is callback when visiting Workflow node after visiting its children.
 func (r *RuleBase) VisitWorkflowPost(node *Workflow) error { return nil }
 
+// VisitActionPre is callback when visiting Workflow node before visiting its children.
+func (r *RuleBase) VisitActionPre(node *Action) error { return nil }
+
+// VisitActionPost is callback when visiting Workflow node after visiting its children.
+func (r *RuleBase) VisitActionPost(node *Action) error { return nil }
+
 // Error creates a new error from the source position and the error message and stores it in the
 // rule instance. The errors can be accessed by Errs method.
 func (r *RuleBase) Error(pos *Pos, msg string) {
diff --git a/rule_branding.go b/rule_branding.go
new file mode 100644
index 000000000..0210a0f2d
--- /dev/null
+++ b/rule_branding.go
@@ -0,0 +1,36 @@
+package actionlint
+
+// RuleBranding is a rule to check branding information of actions
+type RuleBranding struct {
+	RuleBase
+}
+
+// NewRuleBranding creates new RuleBranding instance
+func NewRuleBranding() *RuleBranding {
+	return &RuleBranding{
+		RuleBase: RuleBase{
+			name: "branding",
+			desc: "Checks for valid branding information of actions",
+		},
+	}
+}
+
+// VisitActionPre is callback when visiting Action node before visiting its children.
+func (rule *RuleBranding) VisitActionPre(n *Action) error {
+	if n.Branding == nil { // Branding is optional
+		return nil
+	}
+
+	// TODO auto-extract it from GitHub docs
+	valid_colors := []string{"white", "yellow", "blue", "green", "orange", "red", "purple", "gray-dark"}
+	if n.Branding.Color != nil && !contains(valid_colors, n.Branding.Color.Value) {
+		rule.Errorf(n.Branding.Color.Pos, "invalid color %q. valid colors are %v", n.Branding.Color.Value, valid_colors)
+	}
+
+	// TODO auto-extract it from GitHub docs
+	valid_icons := []string{"activity", "airplay", "alert-circle", "alert-octagon", "alert-triangle", "align-center", "align-justify", "align-left", "align-right", "anchor", "aperture", "archive", "arrow-down-circle", "arrow-down-left", "arrow-down-right", "arrow-down", "arrow-left-circle", "arrow-left", "arrow-right-circle", "arrow-right", "arrow-up-circle", "arrow-up-left", "arrow-up-right", "arrow-up", "at-sign", "award", "bar-chart-2", "bar-chart", "battery-charging", "battery", "bell-off", "bell", "bluetooth", "bold", "book-open", "book", "bookmark", "box", "briefcase", "calendar", "camera-off", "camera", "cast", "check-circle", "check-square", "check", "chevron-down", "chevron-left", "chevron-right", "chevron-up", "chevrons-down", "chevrons-left", "chevrons-right", "chevrons-up", "circle", "clipboard", "clock", "cloud-drizzle", "cloud-lightning", "cloud-off", "cloud-rain", "cloud-snow", "cloud", "code", "command", "compass", "copy", "corner-down-left", "corner-down-right", "corner-left-down", "corner-left-up", "corner-right-down", "corner-right-up", "corner-up-left", "corner-up-right", "cpu", "credit-card", "crop", "crosshair", "database", "delete", "disc", "dollar-sign", "download-cloud", "download", "droplet", "edit-2", "edit-3", "edit", "external-link", "eye-off", "eye", "fast-forward", "feather", "file-minus", "file-plus", "file-text", "file", "film", "filter", "flag", "folder-minus", "folder-plus", "folder", "gift", "git-branch", "git-commit", "git-merge", "git-pull-request", "globe", "grid", "hard-drive", "hash", "headphones", "heart", "help-circle", "home", "image", "inbox", "info", "italic", "layers", "layout", "life-buoy", "link-2", "link", "list", "loader", "lock", "log-in", "log-out", "mail", "map-pin", "map", "maximize-2", "maximize", "menu", "message-circle", "message-square", "mic-off", "mic", "minimize-2", "minimize", "minus-circle", "minus-square", "minus", "monitor", "moon", "more-horizontal", "more-vertical", "move", "music", "navigation-2", "navigation", "octagon", "package", "paperclip", "pause-circle", "pause", "percent", "phone-call", "phone-forwarded", "phone-incoming", "phone-missed", "phone-off", "phone-outgoing", "phone", "pie-chart", "play-circle", "play", "plus-circle", "plus-square", "plus", "pocket", "power", "printer", "radio", "refresh-ccw", "refresh-cw", "repeat", "rewind", "rotate-ccw", "rotate-cw", "rss", "save", "scissors", "search", "send", "server", "settings", "share-2", "share", "shield-off", "shield", "shopping-bag", "shopping-cart", "shuffle", "sidebar", "skip-back", "skip-forward", "slash", "sliders", "smartphone", "speaker", "square", "star", "stop-circle", "sun", "sunrise", "sunset", "tablet", "tag", "target", "terminal", "thermometer", "thumbs-down", "thumbs-up", "toggle-left", "toggle-right", "trash-2", "trash", "trending-down", "trending-up", "triangle", "truck", "tv", "type", "umbrella", "underline", "unlock", "upload-cloud", "upload", "user-check", "user-minus", "user-plus", "user-x", "user", "users", "video-off", "video", "voicemail", "volume-1", "volume-2", "volume-x", "volume", "watch", "wifi-off", "wifi", "wind", "x-circle", "x-square", "x", "zap-off", "zap", "zoom-in", "zoom-out"}
+	if n.Branding.Icon != nil && !contains(valid_icons, n.Branding.Icon.Value) {
+		rule.Errorf(n.Branding.Icon.Pos, "invalid icon %q", n.Branding.Icon.Value)
+	}
+	return nil
+}
diff --git a/rule_expression.go b/rule_expression.go
index e7413661a..b4d658dab 100644
--- a/rule_expression.go
+++ b/rule_expression.go
@@ -267,6 +267,47 @@ func (rule *RuleExpression) VisitJobPost(n *Job) error {
 	return nil
 }
 
+// VisitActionPre is callback when visiting Job node before visiting its children.
+func (rule *RuleExpression) VisitActionPre(n *Action) error {
+	rule.needsTy = NewEmptyStrictObjectType()
+	rule.stepsTy = NewEmptyStrictObjectType()
+
+	ity := NewEmptyStrictObjectType()
+	rule.inputsTy = ity
+
+	for k := range n.Inputs {
+		ity.Props[k] = AnyType{}
+	}
+
+	for _, v := range n.Inputs {
+		rule.checkString(v.Default, "jobs.<job_id>.inputs.<input_id>.default")
+	}
+
+	switch r := n.Runs.(type) {
+	case *JavaScriptRuns:
+		rule.checkIfCondition(r.PreIf, "runs.pre-if")
+		rule.checkIfCondition(r.PostIf, "runs.post-if")
+	case *DockerContainerRuns:
+		rule.checkEnv(r.Env, "runs.env")
+	}
+
+	return nil
+}
+
+// VisitActionPost is callback when visiting Job node after visiting its children
+func (rule *RuleExpression) VisitActionPost(n *Action) error {
+	// 'outputs' sections are evaluated after all steps are run
+	for _, output := range n.Outputs {
+		rule.checkString(output.Value, "jobs.<job_id>.outputs.<output_id>")
+	}
+
+	rule.matrixTy = nil
+	rule.stepsTy = nil
+	rule.needsTy = nil
+
+	return nil
+}
+
 // VisitStep is callback when visiting Step node.
 func (rule *RuleExpression) VisitStep(n *Step) error {
 	rule.checkString(n.Name, "jobs.<job_id>.steps.name")
diff --git a/rule_id.go b/rule_id.go
index b491e5e60..6d9084887 100644
--- a/rule_id.go
+++ b/rule_id.go
@@ -41,6 +41,19 @@ func (rule *RuleID) VisitJobPost(n *Job) error {
 	return nil
 }
 
+// VisitActionPre is callback when visiting Job node before visiting its children.
+func (rule *RuleID) VisitActionPre(n *Action) error {
+	rule.seen = map[string]*Pos{}
+
+	return nil
+}
+
+// VisitActionPost is callback when visiting Job node after visiting its children.
+func (rule *RuleID) VisitActionPost(n *Action) error {
+	rule.seen = nil
+	return nil
+}
+
 // VisitStep is callback when visiting Step node.
 func (rule *RuleID) VisitStep(n *Step) error {
 	if n.ID == nil {
diff --git a/rule_shellcheck.go b/rule_shellcheck.go
index b8f5b10e3..7494f6413 100644
--- a/rule_shellcheck.go
+++ b/rule_shellcheck.go
@@ -107,6 +107,12 @@ func (rule *RuleShellcheck) VisitWorkflowPost(n *Workflow) error {
 	return rule.cmd.wait() // Wait until all processes running for this rule
 }
 
+// VisitActionPost is callback when visiting Action node after visiting its children.
+func (rule *RuleShellcheck) VisitActionPost(n *Action) error {
+	rule.workflowShell = ""
+	return rule.cmd.wait() // Wait until all processes running for this rule
+}
+
 func (rule *RuleShellcheck) getShellName(exec *ExecRun) string {
 	if exec.Shell != nil {
 		return exec.Shell.Value
diff --git a/testdata/actions/err/branding-unknown-missing-keys.out b/testdata/actions/err/branding-unknown-missing-keys.out
new file mode 100644
index 000000000..981025760
--- /dev/null
+++ b/testdata/actions/err/branding-unknown-missing-keys.out
@@ -0,0 +1,3 @@
+test.yaml:7:3: unexpected key "new" for "branding" section. expected one of "color", "icon" [syntax-check]
+test.yaml:7:3: "icon" is required for branding information [syntax-check]
+test.yaml:7:3: "color" is required for branding information [syntax-check]
diff --git a/testdata/actions/err/branding-unknown-missing-keys.yaml b/testdata/actions/err/branding-unknown-missing-keys.yaml
new file mode 100644
index 000000000..c11f5e168
--- /dev/null
+++ b/testdata/actions/err/branding-unknown-missing-keys.yaml
@@ -0,0 +1,7 @@
+name: "Branding Test"
+description: "Ensure a known color is configured"
+runs:
+  using: "node12"
+  main: "index.js"
+branding:
+  new: key
diff --git a/testdata/actions/err/branding-unknown-values.out b/testdata/actions/err/branding-unknown-values.out
new file mode 100644
index 000000000..8f45ad9b1
--- /dev/null
+++ b/testdata/actions/err/branding-unknown-values.out
@@ -0,0 +1,2 @@
+test.yaml:7:10: invalid color "navy". valid colors are [white yellow blue green orange red purple gray-dark] [branding]
+test.yaml:8:9: invalid icon "github" [branding]
diff --git a/testdata/actions/err/branding-unknown-values.yaml b/testdata/actions/err/branding-unknown-values.yaml
new file mode 100644
index 000000000..4507cc2fd
--- /dev/null
+++ b/testdata/actions/err/branding-unknown-values.yaml
@@ -0,0 +1,8 @@
+name: "Branding Test"
+description: "Ensure a known color is configured"
+runs:
+  using: "node12"
+  main: "index.js"
+branding:
+  color: "navy"
+  icon: "github"
diff --git a/testdata/actions/err/composite-invalid-refs.out b/testdata/actions/err/composite-invalid-refs.out
new file mode 100644
index 000000000..e3fe529dd
--- /dev/null
+++ b/testdata/actions/err/composite-invalid-refs.out
@@ -0,0 +1,4 @@
+test.yaml:8:18: undefined variable "unknown". available variables are "env", "github", "inputs", "job", "matrix", "needs", "runner", "secrets", "steps", "strategy", "vars" [expression]
+test.yaml:12:5: output value is required for composite actions [syntax-check]
+test.yaml:16:16: property "unknown_step" is not defined in object type {hello: {conclusion: string; outcome: string; outputs: {string => string}}} [expression]
+test.yaml:21:22: property "unknown_input" is not defined in object type {test: any; token: any} [expression]
diff --git a/testdata/actions/err/composite-invalid-refs.yaml b/testdata/actions/err/composite-invalid-refs.yaml
new file mode 100644
index 000000000..93b89ad53
--- /dev/null
+++ b/testdata/actions/err/composite-invalid-refs.yaml
@@ -0,0 +1,23 @@
+name: "Composite with invalid refs"
+description: "Output value is only valid for composite actions"
+inputs:
+  token:
+    required: true
+    description: "GitHub Token to use"
+  test:
+    default: ${{ unknown.token }}
+    description: "Test expression evaluation of default"
+outputs:
+  no_value:
+    description: "Output without value"
+    # ERROR no value
+  unknown_step:
+    description: "Output referencing unknown step"
+    value: ${{ steps.unknown_step.outputs.unknown }}
+
+runs:
+  using: composite
+  steps:
+    - run: "echo ${{ inputs.unknown_input }}"
+      id: hello
+      shell: bash
diff --git a/testdata/actions/err/composite-invalid-steps.out b/testdata/actions/err/composite-invalid-steps.out
new file mode 100644
index 000000000..c35551abf
--- /dev/null
+++ b/testdata/actions/err/composite-invalid-steps.out
@@ -0,0 +1 @@
+test.yaml:7:7: "shell" is required to run script in step as part of composite actions [syntax-check]
diff --git a/testdata/actions/err/composite-invalid-steps.yaml b/testdata/actions/err/composite-invalid-steps.yaml
new file mode 100644
index 000000000..d2a375b53
--- /dev/null
+++ b/testdata/actions/err/composite-invalid-steps.yaml
@@ -0,0 +1,7 @@
+name: "Testing Composite Steps"
+description: "Ensure various composite step errors are caught"
+runs:
+  using: "composite"
+  steps:
+    # Error missing shell
+    - run: "echo 'Hello World!'"
diff --git a/testdata/actions/err/docker-with-output-value.out b/testdata/actions/err/docker-with-output-value.out
new file mode 100644
index 000000000..ca03b8664
--- /dev/null
+++ b/testdata/actions/err/docker-with-output-value.out
@@ -0,0 +1 @@
+test.yaml:5:5: output value is only allowed for composite actions [syntax-check]
diff --git a/testdata/actions/err/docker-with-output-value.yaml b/testdata/actions/err/docker-with-output-value.yaml
new file mode 100644
index 000000000..6ad36aacf
--- /dev/null
+++ b/testdata/actions/err/docker-with-output-value.yaml
@@ -0,0 +1,10 @@
+name: "Docker With Output Value"
+description: "Output value is only valid for composite actions"
+outputs:
+  my_output:
+    description: "My output"
+    value: "my value"
+
+runs:
+  using: docker
+  image: true:v1.0.0
diff --git a/testdata/actions/err/empty.out b/testdata/actions/err/empty.out
new file mode 100644
index 000000000..10ac2130d
--- /dev/null
+++ b/testdata/actions/err/empty.out
@@ -0,0 +1 @@
+test.yaml:1:1: action is empty [syntax-check]
diff --git a/testdata/actions/err/empty.yaml b/testdata/actions/err/empty.yaml
new file mode 100644
index 000000000..e69de29bb
diff --git a/testdata/actions/err/implicit-js.out b/testdata/actions/err/implicit-js.out
new file mode 100644
index 000000000..4d27c8fa9
--- /dev/null
+++ b/testdata/actions/err/implicit-js.out
@@ -0,0 +1 @@
+test.yaml:4:3: "using" is required to define what to execute [syntax-check]
diff --git a/testdata/actions/err/implicit-js.yaml b/testdata/actions/err/implicit-js.yaml
new file mode 100644
index 000000000..e9dd1e564
--- /dev/null
+++ b/testdata/actions/err/implicit-js.yaml
@@ -0,0 +1,4 @@
+name: "Implicit Runs"
+description: "Even if only JavaScript options are declared, a using value is still required"
+runs:
+  main: "index.js"
diff --git a/testdata/actions/err/js-invalid-inputs-outputs.out b/testdata/actions/err/js-invalid-inputs-outputs.out
new file mode 100644
index 000000000..cbf2ed393
--- /dev/null
+++ b/testdata/actions/err/js-invalid-inputs-outputs.out
@@ -0,0 +1,5 @@
+test.yaml:5:5: "description" property is missing in specification of input "without_description" [syntax-check]
+test.yaml:8:5: unexpected key "type" for "input" section. expected one of "default", "deprecationMessage", "description", "required" [syntax-check]
+test.yaml:11:5: output value is only allowed for composite actions [syntax-check]
+test.yaml:13:24: "output_without_desc" outputs should not be empty. please remove this section if it's unnecessary [syntax-check]
+test.yaml:16:5: unexpected key "unknown_key" for "output" section. expected one of "description", "value" [syntax-check]
diff --git a/testdata/actions/err/js-invalid-inputs-outputs.yaml b/testdata/actions/err/js-invalid-inputs-outputs.yaml
new file mode 100644
index 000000000..0b57f7a25
--- /dev/null
+++ b/testdata/actions/err/js-invalid-inputs-outputs.yaml
@@ -0,0 +1,20 @@
+name: "JS With Output Value"
+description: "Output value is only valid for composite actions"
+inputs:
+  without_description:
+    required: true
+  with_extra_key:
+    description: "Warning about extra keys like type"
+    type: string
+outputs:
+  output_with_value:
+    description: "My output"
+    value: "my value"
+  output_without_desc: {}
+  output_with_unknown_key:
+    description: "Only description is allowed as key"
+    unknown_key: "my value"
+
+runs:
+  using: node20
+  main: index.js
diff --git a/testdata/actions/err/missing-composite.out b/testdata/actions/err/missing-composite.out
new file mode 100644
index 000000000..7dd273418
--- /dev/null
+++ b/testdata/actions/err/missing-composite.out
@@ -0,0 +1 @@
+test.yaml:4:3: "steps" is required for a composite action [syntax-check]
diff --git a/testdata/actions/err/missing-composite.yaml b/testdata/actions/err/missing-composite.yaml
new file mode 100644
index 000000000..1351e2b9d
--- /dev/null
+++ b/testdata/actions/err/missing-composite.yaml
@@ -0,0 +1,4 @@
+name: "Missing Require Values"
+description: "Composite action with missing required values"
+runs:
+  using: composite
diff --git a/testdata/actions/err/missing-docker.out b/testdata/actions/err/missing-docker.out
new file mode 100644
index 000000000..21ad83d84
--- /dev/null
+++ b/testdata/actions/err/missing-docker.out
@@ -0,0 +1 @@
+test.yaml:4:3: "image" is required for a docker container action [syntax-check]
diff --git a/testdata/actions/err/missing-docker.yaml b/testdata/actions/err/missing-docker.yaml
new file mode 100644
index 000000000..25c3d7eb6
--- /dev/null
+++ b/testdata/actions/err/missing-docker.yaml
@@ -0,0 +1,4 @@
+name: "Missing Require Values"
+description: "Docker action with missing required values"
+runs:
+  using: docker
diff --git a/testdata/actions/err/missing-js.out b/testdata/actions/err/missing-js.out
new file mode 100644
index 000000000..ae7b18ec0
--- /dev/null
+++ b/testdata/actions/err/missing-js.out
@@ -0,0 +1 @@
+test.yaml:4:3: "main" is required for a javascript action [syntax-check]
diff --git a/testdata/actions/err/missing-js.yaml b/testdata/actions/err/missing-js.yaml
new file mode 100644
index 000000000..29ed3efcd
--- /dev/null
+++ b/testdata/actions/err/missing-js.yaml
@@ -0,0 +1,4 @@
+name: "Missing Require Values"
+description: "JavaScript action with missing required values"
+runs:
+  using: node20
diff --git a/testdata/actions/err/missing-using.out b/testdata/actions/err/missing-using.out
new file mode 100644
index 000000000..d2e163b61
--- /dev/null
+++ b/testdata/actions/err/missing-using.out
@@ -0,0 +1,2 @@
+test.yaml:3:7: runs should not be empty. please remove this section if it's unnecessary [syntax-check]
+test.yaml:3:7: "using" is required to define what to execute [syntax-check]
diff --git a/testdata/actions/err/missing-using.yaml b/testdata/actions/err/missing-using.yaml
new file mode 100644
index 000000000..895f7b987
--- /dev/null
+++ b/testdata/actions/err/missing-using.yaml
@@ -0,0 +1,3 @@
+name: "Missing Using Value"
+description: "Unknown execution type"
+runs: {}
diff --git a/testdata/actions/err/mixed-runs1.out b/testdata/actions/err/mixed-runs1.out
new file mode 100644
index 000000000..5bb59cc96
--- /dev/null
+++ b/testdata/actions/err/mixed-runs1.out
@@ -0,0 +1,2 @@
+test.yaml:5:3: this action declares it uses docker container but has foreign keys [syntax-check]
+test.yaml:6:3: this action defines parameter steps for composite actions, but is something else [syntax-check]
diff --git a/testdata/actions/err/mixed-runs1.yaml b/testdata/actions/err/mixed-runs1.yaml
new file mode 100644
index 000000000..8062b8e23
--- /dev/null
+++ b/testdata/actions/err/mixed-runs1.yaml
@@ -0,0 +1,7 @@
+name: "Missing Using Value"
+description: "Unknown execution type"
+runs:
+  main: index.js  # appears like JavaScript action
+  using: docker  # it is actually docker
+  steps:  # composite key
+    - uses: action/checkout@v4
diff --git a/testdata/actions/err/mixed-runs2.out b/testdata/actions/err/mixed-runs2.out
new file mode 100644
index 000000000..384fef295
--- /dev/null
+++ b/testdata/actions/err/mixed-runs2.out
@@ -0,0 +1,2 @@
+test.yaml:6:3: this action declares it uses javascript but has foreign keys [syntax-check]
+test.yaml:7:3: this action defines parameter image for javascript actions, but is something else [syntax-check]
diff --git a/testdata/actions/err/mixed-runs2.yaml b/testdata/actions/err/mixed-runs2.yaml
new file mode 100644
index 000000000..df128a056
--- /dev/null
+++ b/testdata/actions/err/mixed-runs2.yaml
@@ -0,0 +1,7 @@
+name: "Missing Using Value"
+description: "Unknown execution type"
+runs:
+  steps:  # composite key
+    - uses: action/checkout@v4
+  using: node20  # it is actually JavaScript
+  image: true:v1.0.0  # docker specific key
diff --git a/testdata/actions/err/mixed-runs3.out b/testdata/actions/err/mixed-runs3.out
new file mode 100644
index 000000000..d73e9c7be
--- /dev/null
+++ b/testdata/actions/err/mixed-runs3.out
@@ -0,0 +1,2 @@
+test.yaml:5:3: this action declares it is a composite action but has foreign keys [syntax-check]
+test.yaml:6:3: this action defines parameter main for javascript actions, but is something else [syntax-check]
diff --git a/testdata/actions/err/mixed-runs3.yaml b/testdata/actions/err/mixed-runs3.yaml
new file mode 100644
index 000000000..447c290c4
--- /dev/null
+++ b/testdata/actions/err/mixed-runs3.yaml
@@ -0,0 +1,6 @@
+name: "Missing Using Value"
+description: "Unknown execution type"
+runs:
+  image: true:v1.0.0  # appears like docker runs block
+  using: composite  # it is actually composite
+  main: index.js  # JavaScript specfici key
diff --git a/testdata/actions/err/nothing.out b/testdata/actions/err/nothing.out
new file mode 100644
index 000000000..92f616634
--- /dev/null
+++ b/testdata/actions/err/nothing.out
@@ -0,0 +1,4 @@
+test.yaml:1:1: unexpected key "unknown" for "action" section. expected one of "author", "branding", "description", "inputs", "name", "outputs", "runs" [syntax-check]
+test.yaml:1:1: "name" property is missing in action metadata [syntax-check]
+test.yaml:1:1: "description" property is missing in action metadata [syntax-check]
+test.yaml:1:1: "runs" section is missing in action metadata [syntax-check]
diff --git a/testdata/actions/err/nothing.yaml b/testdata/actions/err/nothing.yaml
new file mode 100644
index 000000000..1c720c637
--- /dev/null
+++ b/testdata/actions/err/nothing.yaml
@@ -0,0 +1 @@
+unknown: key
diff --git a/testdata/actions/err/unknown-using.out b/testdata/actions/err/unknown-using.out
new file mode 100644
index 000000000..d2ccad5fa
--- /dev/null
+++ b/testdata/actions/err/unknown-using.out
@@ -0,0 +1,2 @@
+test.yaml:4:3: unexpected key "unknown-key" for "runs" section. expected one of "args", "entrypoint", "env", "image", "main", "post", "post-entrypoint", "post-if", "pre", "pre-entrypoint", "pre-if", "steps", "using" [syntax-check]
+test.yaml:5:10: unknown action type python3.12, (only javascript, docker and composite are supported) [syntax-check]
diff --git a/testdata/actions/err/unknown-using.yaml b/testdata/actions/err/unknown-using.yaml
new file mode 100644
index 000000000..a10794e03
--- /dev/null
+++ b/testdata/actions/err/unknown-using.yaml
@@ -0,0 +1,5 @@
+name: "Unknown Using Value"
+description: "Unknown execution type"
+runs:
+  unknown-key: Value
+  using: python3.12
diff --git a/testdata/actions/ok/branding.yaml b/testdata/actions/ok/branding.yaml
new file mode 100644
index 000000000..b2dd5e216
--- /dev/null
+++ b/testdata/actions/ok/branding.yaml
@@ -0,0 +1,11 @@
+name: 'My action'
+author: 'rhysd <https://rhysd.github.io>'
+description: 'my action'
+
+runs:
+  using: 'node20'
+  main: 'index.js'
+
+branding:
+  color: red
+  icon: airplay
diff --git a/testdata/actions/ok/complex-composite.yaml b/testdata/actions/ok/complex-composite.yaml
new file mode 100644
index 000000000..2e88d0026
--- /dev/null
+++ b/testdata/actions/ok/complex-composite.yaml
@@ -0,0 +1,42 @@
+name: 'Complex JavaScript Action'
+description: 'Try to set as many options as possible'
+author: 'rhysd <https://rhysd.github.io>'
+inputs:
+  base_uri:
+    required: true
+    description: 'Provide the AST portal URL'
+  cx_tenant:
+    required: true
+    description: 'Provide the Tenant for AST portal URL'
+  cx_client_id:
+    required: true
+    description: 'Client ID for AST portal authentication'
+  cx_client_secret:
+    required: true
+    description: 'Secret key for AST portal authentication'
+  project_name:
+    required: false
+    default: ${{ github.repository }} # default repo name
+    description: 'Select a Checkmarx Project Name'
+  branch:
+    required: false
+    default: ${{ github.head_ref || github.ref }} # default branch name
+    description: 'Branch name'
+  github_token:
+    required: false
+    default: ${{ github.token }}
+    description: 'GitHub API Token'
+  additional_params:
+    required: false
+    default: ''
+    description: 'Additional parameters for AST scan'
+outputs:
+  random-number:
+    description: "Random number"
+    value: ${{ steps.random-number-generator.outputs.random-id }}
+runs:
+  steps:
+    - id: random-number-generator
+      run: echo "random-id=$RANDOM)" >> "$GITHUB_OUTPUT"
+      shell: bash
+  using: "composite"
diff --git a/testdata/actions/ok/complex-docker.yaml b/testdata/actions/ok/complex-docker.yaml
new file mode 100644
index 000000000..3ae8c1b72
--- /dev/null
+++ b/testdata/actions/ok/complex-docker.yaml
@@ -0,0 +1,84 @@
+name: 'Complex Docker Action'
+description: 'Try to set as many options as possible'
+author: 'rhysd <https://rhysd.github.io>'
+inputs:
+  base_uri:
+    required: true
+    description: 'Provide the AST portal URL'
+  cx_tenant:
+    required: true
+    description: 'Provide the Tenant for AST portal URL'
+  cx_client_id:
+    required: true
+    description: 'Client ID for AST portal authentication'
+  cx_client_secret:
+    required: true
+    description: 'Secret key for AST portal authentication'
+  project_name:
+    required: false
+    default: ${{ github.repository }} # default repo name
+    description: 'Select a Checkmarx Project Name'
+  branch:
+    required: false
+    default: ${{ github.head_ref || github.ref }} # default branch name
+    description: 'Branch name'
+  github_token:
+    required: false
+    default: ${{ github.token }}
+    description: 'GitHub API Token'
+  additional_params:
+    required: false
+    default: ''
+    description: 'Additional parameters for AST scan'
+  repo_name:
+    required: false
+    default:  ${{ github.event.repository.name }}
+    description: "Repository name for PR decoration"
+  namespace:
+    required: false
+    default: ${{ github.repository_owner }}
+    description: "Organization name to create the Pr comment"
+  pr_number:
+    required: false
+    default: ${{ github.event.number }}
+    description: "Pr Number of the pull request that needs the decoration"
+outputs: 
+  cxcli:
+    description: output from cli
+  cxScanID:
+    description: scan ID output from cli
+runs:
+  image: 'Dockerfile'
+  args:
+    - ${{ inputs.base_uri }}
+    - ${{ inputs.cx_tenant }}
+    - ${{ inputs.cx_client_id }}
+    - ${{ inputs.cx_client_secret }}
+    - ${{ inputs.github_token }}
+    - ${{ inputs.project_name }}
+    - ${{ inputs.additional_params }}
+    - ${{ inputs.repo_name }}
+    - ${{ inputs.namespace }}
+    - ${{ inputs.pr_number }}
+  entrypoint: '/app/entrypoint.sh'
+  using: 'docker'
+  # post-if: cancelled()
+  post-entrypoint: '/app/cleanup.sh'
+  pre-entrypoint: '/app/prepare.sh'
+
+  env:
+    CX_BASE_URI: "${{ inputs.base_uri }}"
+    CX_TENANT: ${{ inputs.cx_tenant }}
+    CX_CLIENT_ID: ${{ inputs.cx_client_id }}
+    CX_CLIENT_SECRET: ${{ inputs.cx_client_secret }}
+    GITHUB_TOKEN: ${{ inputs.github_token }}
+    BRANCH: ${{ inputs.branch }}
+    PROJECT_NAME: ${{ inputs.project_name }}
+    ADDITIONAL_PARAMS: ${{ inputs.additional_params }}
+    REPO_NAME: ${{ inputs.repo_name }}
+    NAMESPACE: ${{ inputs.namespace }}
+    PR_NUMBER: ${{ inputs.pr_number }}
+
+branding:
+  icon: 'check'
+  color: 'green'
diff --git a/testdata/actions/ok/complex-js.yaml b/testdata/actions/ok/complex-js.yaml
new file mode 100644
index 000000000..41ea25b2a
--- /dev/null
+++ b/testdata/actions/ok/complex-js.yaml
@@ -0,0 +1,33 @@
+name: 'Complex JavaScript Action'
+description: 'Try to set as many options as possible'
+author: 'rhysd <https://rhysd.github.io>'
+inputs:
+  base_uri:
+    description: 'Only description is required for inputs'
+  base_url:
+    description: 'Only description is required for inputs'
+    deprecationMessage: "Use 'base_uri' instead"
+  api_secret:
+    required: true
+    description: 'Secret key for the API'
+  github_token:
+    required: false
+    default: ${{ github.token }}
+    description: 'GitHub API Token'
+  branch:
+    required: false
+    description: 'Branch name'
+outputs:
+  id:
+    description: create id of resource
+runs:
+  main: "index.js"
+  pre: "prepare.js"
+  pre-if: runner.os == 'windows'  # failure()
+  using: 'node20'  # unusual position
+  post: cleanup.js
+  post-if: runner.os == 'linux'
+
+branding:
+  icon: 'check'
+  color: 'green'
diff --git a/testdata/actions/ok/minimal-composite.yaml b/testdata/actions/ok/minimal-composite.yaml
new file mode 100644
index 000000000..3b59811be
--- /dev/null
+++ b/testdata/actions/ok/minimal-composite.yaml
@@ -0,0 +1,6 @@
+name: 'Minimal Docker Action'
+description: 'Ensure most keys can be left out'
+runs:
+  using: 'composite'
+  steps:
+    - uses: actions/checkout@v4
diff --git a/testdata/actions/ok/minimal-docker.yaml b/testdata/actions/ok/minimal-docker.yaml
new file mode 100644
index 000000000..0273586c1
--- /dev/null
+++ b/testdata/actions/ok/minimal-docker.yaml
@@ -0,0 +1,5 @@
+name: 'Minimal Docker Action'
+description: 'Ensure most keys can be left out'
+runs:
+  using: 'docker'
+  image: 'true:v1.0.0'
diff --git a/testdata/actions/ok/minimal-js.yaml b/testdata/actions/ok/minimal-js.yaml
new file mode 100644
index 000000000..ec30e0dcb
--- /dev/null
+++ b/testdata/actions/ok/minimal-js.yaml
@@ -0,0 +1,5 @@
+name: 'Minimal JavaScript Action'
+description: 'Ensure most keys can be left out'
+runs:
+  using: 'node20'
+  main: 'index.js'
diff --git a/testdata/actions/ok/reordered-js.yaml b/testdata/actions/ok/reordered-js.yaml
new file mode 100644
index 000000000..fc169fc73
--- /dev/null
+++ b/testdata/actions/ok/reordered-js.yaml
@@ -0,0 +1,5 @@
+runs:
+  main: 'index.js'
+  using: 'node20'
+description: 'Ensure most keys can be left out'
+name: 'Minimal JavaScript Action'
diff --git a/testdata/detect_format/actions/action.yaml b/testdata/detect_format/actions/action.yaml
new file mode 100644
index 000000000..acf5f199e
--- /dev/null
+++ b/testdata/detect_format/actions/action.yaml
@@ -0,0 +1,5 @@
+name: "Test format"
+description: "Should be detected as action due to action.yaml filename"
+runs:
+  using: node20
+  main: index.js
diff --git a/testdata/detect_format/actions/action.yml b/testdata/detect_format/actions/action.yml
new file mode 100644
index 000000000..d718de00f
--- /dev/null
+++ b/testdata/detect_format/actions/action.yml
@@ -0,0 +1,5 @@
+name: "Test format"
+description: "Should be detected as action due to action.yml filename"
+runs:
+  using: node20
+  main: index.js
diff --git a/testdata/detect_format/actions/stdin b/testdata/detect_format/actions/stdin
new file mode 100644
index 000000000..7125ed3a6
--- /dev/null
+++ b/testdata/detect_format/actions/stdin
@@ -0,0 +1,5 @@
+name: "Test format"
+description: "Should be detected as action due to 'runs' key"
+runs:
+  using: node20
+  main: index.js
diff --git a/testdata/detect_format/workflows/.github/workflows/action.yaml b/testdata/detect_format/workflows/.github/workflows/action.yaml
new file mode 100644
index 000000000..efe14e23a
--- /dev/null
+++ b/testdata/detect_format/workflows/.github/workflows/action.yaml
@@ -0,0 +1,6 @@
+on: push
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo 'action.yaml file in .github/workflows should still be parsed as workflow'
diff --git a/testdata/detect_format/workflows/.github/workflows/action.yml b/testdata/detect_format/workflows/.github/workflows/action.yml
new file mode 100644
index 000000000..870817c35
--- /dev/null
+++ b/testdata/detect_format/workflows/.github/workflows/action.yml
@@ -0,0 +1,6 @@
+on: push
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo 'action.yml file in .github/workflows should still be parsed as workflow'
diff --git a/testdata/detect_format/workflows/empty b/testdata/detect_format/workflows/empty
new file mode 100644
index 000000000..4b8d1d349
--- /dev/null
+++ b/testdata/detect_format/workflows/empty
@@ -0,0 +1 @@
+# default to workflow for empty files (although does not make a big difference)
diff --git a/testdata/detect_format/workflows/stdin b/testdata/detect_format/workflows/stdin
new file mode 100644
index 000000000..c6f5a15c5
--- /dev/null
+++ b/testdata/detect_format/workflows/stdin
@@ -0,0 +1,3 @@
+on: push
+jobs: []
+# default to workflow
diff --git a/testdata/projects/broken_local_action/workflows/test.yaml b/testdata/projects/broken_local_action/.github/workflows/test.yaml
similarity index 100%
rename from testdata/projects/broken_local_action/workflows/test.yaml
rename to testdata/projects/broken_local_action/.github/workflows/test.yaml
diff --git a/testdata/projects/broken_reusable_workflow.out b/testdata/projects/broken_reusable_workflow.out
index 4f4a64016..49736e946 100644
--- a/testdata/projects/broken_reusable_workflow.out
+++ b/testdata/projects/broken_reusable_workflow.out
@@ -1,4 +1,4 @@
-/workflows/test\.yaml:5:11: error while parsing reusable workflow "\./reusable/broken\.yaml": yaml: .+ \[workflow-call\]/
-workflows/test.yaml:7:11: error while parsing reusable workflow "./reusable/no_hook.yaml": "workflow_call" event trigger is not found in "on:" at line:1, column:5 [workflow-call]
-workflows/test.yaml:9:11: error while parsing reusable workflow "./reusable/no_on.yaml": "on:" is not found [workflow-call]
-/workflows/test\.yaml:15:11: error while parsing reusable workflow "\./reusable/broken_secrets\.yaml": yaml: .+ \[workflow-call\]/
+/.github/workflows/test\.yaml:5:11: error while parsing reusable workflow "\./reusable/broken\.yaml": yaml: .+ \[workflow-call\]/
+.github/workflows/test.yaml:7:11: error while parsing reusable workflow "./reusable/no_hook.yaml": "workflow_call" event trigger is not found in "on:" at line:1, column:5 [workflow-call]
+.github/workflows/test.yaml:9:11: error while parsing reusable workflow "./reusable/no_on.yaml": "on:" is not found [workflow-call]
+/.github/workflows/test\.yaml:15:11: error while parsing reusable workflow "\./reusable/broken_secrets\.yaml": yaml: .+ \[workflow-call\]/
diff --git a/testdata/projects/broken_reusable_workflow/workflows/test.yaml b/testdata/projects/broken_reusable_workflow/.github/workflows/test.yaml
similarity index 100%
rename from testdata/projects/broken_reusable_workflow/workflows/test.yaml
rename to testdata/projects/broken_reusable_workflow/.github/workflows/test.yaml
diff --git a/testdata/projects/config_variables.out b/testdata/projects/config_variables.out
index 8ac2f2878..ef19d3e53 100644
--- a/testdata/projects/config_variables.out
+++ b/testdata/projects/config_variables.out
@@ -1 +1 @@
-workflows/test.yaml:14:24: undefined configuration variable "piyo". defined configuration variables in actionlint.yaml are "FOO", "WOO" [expression]
+.github/workflows/test.yaml:14:24: undefined configuration variable "piyo". defined configuration variables in actionlint.yaml are "FOO", "WOO" [expression]
diff --git a/testdata/projects/config_variables/actionlint.yaml b/testdata/projects/config_variables/.github/actionlint.yaml
similarity index 100%
rename from testdata/projects/config_variables/actionlint.yaml
rename to testdata/projects/config_variables/.github/actionlint.yaml
diff --git a/testdata/projects/config_variables/workflows/test.yaml b/testdata/projects/config_variables/.github/workflows/test.yaml
similarity index 100%
rename from testdata/projects/config_variables/workflows/test.yaml
rename to testdata/projects/config_variables/.github/workflows/test.yaml
diff --git a/testdata/projects/example_inputs_secrets_in_workflow_call.out b/testdata/projects/example_inputs_secrets_in_workflow_call.out
index 6af0b6160..262b7c445 100644
--- a/testdata/projects/example_inputs_secrets_in_workflow_call.out
+++ b/testdata/projects/example_inputs_secrets_in_workflow_call.out
@@ -1,6 +1,6 @@
-workflows/test.yaml:6:11: input "name" is required by "./.github/workflows/reusable.yaml" reusable workflow [workflow-call]
-workflows/test.yaml:6:11: secret "password" is required by "./.github/workflows/reusable.yaml" reusable workflow [workflow-call]
-workflows/test.yaml:9:7: input "user" is not defined in "./.github/workflows/reusable.yaml" reusable workflow. defined inputs are "id", "message", "name" [workflow-call]
-workflows/test.yaml:13:7: secret "credentials" is not defined in "./.github/workflows/reusable.yaml" reusable workflow. defined secret is "password" [workflow-call]
-workflows/test.yaml:22:11: input "id" is typed as number by reusable workflow "./.github/workflows/reusable.yaml". bool value cannot be assigned [expression]
-workflows/test.yaml:24:16: input "message" is typed as string by reusable workflow "./.github/workflows/reusable.yaml". null value cannot be assigned [expression]
+.github/workflows/test.yaml:6:11: input "name" is required by "./.github/workflows/reusable.yaml" reusable workflow [workflow-call]
+.github/workflows/test.yaml:6:11: secret "password" is required by "./.github/workflows/reusable.yaml" reusable workflow [workflow-call]
+.github/workflows/test.yaml:9:7: input "user" is not defined in "./.github/workflows/reusable.yaml" reusable workflow. defined inputs are "id", "message", "name" [workflow-call]
+.github/workflows/test.yaml:13:7: secret "credentials" is not defined in "./.github/workflows/reusable.yaml" reusable workflow. defined secret is "password" [workflow-call]
+.github/workflows/test.yaml:22:11: input "id" is typed as number by reusable workflow "./.github/workflows/reusable.yaml". bool value cannot be assigned [expression]
+.github/workflows/test.yaml:24:16: input "message" is typed as string by reusable workflow "./.github/workflows/reusable.yaml". null value cannot be assigned [expression]
diff --git a/testdata/projects/example_inputs_secrets_in_workflow_call/.github/workflows/reusable.yaml b/testdata/projects/example_inputs_secrets_in_workflow_call/.github/workflows/reusable.yaml
index 6b4dbb2d2..a4768fdfd 100644
--- a/testdata/projects/example_inputs_secrets_in_workflow_call/.github/workflows/reusable.yaml
+++ b/testdata/projects/example_inputs_secrets_in_workflow_call/.github/workflows/reusable.yaml
@@ -17,4 +17,4 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - run: echo '${{ outputs.required_input }}'
+      - run: echo '${{ inputs.name }}'
diff --git a/testdata/projects/example_inputs_secrets_in_workflow_call/workflows/test.yaml b/testdata/projects/example_inputs_secrets_in_workflow_call/.github/workflows/test.yaml
similarity index 100%
rename from testdata/projects/example_inputs_secrets_in_workflow_call/workflows/test.yaml
rename to testdata/projects/example_inputs_secrets_in_workflow_call/.github/workflows/test.yaml
diff --git a/testdata/projects/example_workflow_call_outputs_downstream_jobs.out b/testdata/projects/example_workflow_call_outputs_downstream_jobs.out
index 84f6e2a83..1c76070d3 100644
--- a/testdata/projects/example_workflow_call_outputs_downstream_jobs.out
+++ b/testdata/projects/example_workflow_call_outputs_downstream_jobs.out
@@ -1 +1 @@
-workflows/test.yaml:13:24: property "tag" is not defined in object type {version: string} [expression]
+.github/workflows/test.yaml:13:24: property "tag" is not defined in object type {version: string} [expression]
diff --git a/testdata/projects/example_workflow_call_outputs_downstream_jobs/.github/workflows/get-build-info.yaml b/testdata/projects/example_workflow_call_outputs_downstream_jobs/.github/workflows/get-build-info.yaml
index 7117ee1dc..a0b2a5efa 100644
--- a/testdata/projects/example_workflow_call_outputs_downstream_jobs/.github/workflows/get-build-info.yaml
+++ b/testdata/projects/example_workflow_call_outputs_downstream_jobs/.github/workflows/get-build-info.yaml
@@ -3,7 +3,7 @@ on:
   workflow_call:
     outputs:
       version:
-        value: ${{ outputs.version }}
+        value: ${{ jobs.test.outputs.version }}
         description: version of software
 
 jobs:
diff --git a/testdata/projects/example_workflow_call_outputs_downstream_jobs/workflows/test.yaml b/testdata/projects/example_workflow_call_outputs_downstream_jobs/.github/workflows/test.yaml
similarity index 100%
rename from testdata/projects/example_workflow_call_outputs_downstream_jobs/workflows/test.yaml
rename to testdata/projects/example_workflow_call_outputs_downstream_jobs/.github/workflows/test.yaml
diff --git a/testdata/projects/issue-136/workflows/reusable.yaml b/testdata/projects/issue-136/.github/workflows/reusable.yaml
similarity index 100%
rename from testdata/projects/issue-136/workflows/reusable.yaml
rename to testdata/projects/issue-136/.github/workflows/reusable.yaml
diff --git a/testdata/projects/issue-136/workflows/test.yaml b/testdata/projects/issue-136/.github/workflows/test.yaml
similarity index 69%
rename from testdata/projects/issue-136/workflows/test.yaml
rename to testdata/projects/issue-136/.github/workflows/test.yaml
index aaac80c71..0f777f41a 100644
--- a/testdata/projects/issue-136/workflows/test.yaml
+++ b/testdata/projects/issue-136/.github/workflows/test.yaml
@@ -5,4 +5,4 @@ jobs:
     concurrency:
       group: some-group
       cancel-in-progress: true
-    uses: ./workflows/reusable.yaml
+    uses: ./.github/workflows/reusable.yaml
diff --git a/testdata/projects/issue173.out b/testdata/projects/issue173.out
index 8cc83931c..5aafec301 100644
--- a/testdata/projects/issue173.out
+++ b/testdata/projects/issue173.out
@@ -1,4 +1,4 @@
-workflows/workflow1.yaml:9:15: missing input "hello" which is required by action "My action" defined at "./action". all required inputs are "hello" [action]
-workflows/workflow1.yaml:11:11: input "goodbye" is not defined in action "My action" defined at "./action". available inputs are "hello" [action]
-workflows/workflow2.yaml:9:15: missing input "hello" which is required by action "My action" defined at "./action". all required inputs are "hello" [action]
-workflows/workflow2.yaml:11:11: input "goodbye" is not defined in action "My action" defined at "./action". available inputs are "hello" [action]
+.github/workflows/workflow1.yaml:9:15: missing input "hello" which is required by action "My action" defined at "./action". all required inputs are "hello" [action]
+.github/workflows/workflow1.yaml:11:11: input "goodbye" is not defined in action "My action" defined at "./action". available inputs are "hello" [action]
+.github/workflows/workflow2.yaml:9:15: missing input "hello" which is required by action "My action" defined at "./action". all required inputs are "hello" [action]
+.github/workflows/workflow2.yaml:11:11: input "goodbye" is not defined in action "My action" defined at "./action". available inputs are "hello" [action]
diff --git a/testdata/projects/issue173/workflows/workflow1.yaml b/testdata/projects/issue173/.github/workflows/workflow1.yaml
similarity index 100%
rename from testdata/projects/issue173/workflows/workflow1.yaml
rename to testdata/projects/issue173/.github/workflows/workflow1.yaml
diff --git a/testdata/projects/issue173/workflows/workflow2.yaml b/testdata/projects/issue173/.github/workflows/workflow2.yaml
similarity index 100%
rename from testdata/projects/issue173/workflows/workflow2.yaml
rename to testdata/projects/issue173/.github/workflows/workflow2.yaml
diff --git a/testdata/projects/local_action_case_insensitive/workflows/test.yaml b/testdata/projects/local_action_case_insensitive/.github/workflows/test.yaml
similarity index 100%
rename from testdata/projects/local_action_case_insensitive/workflows/test.yaml
rename to testdata/projects/local_action_case_insensitive/.github/workflows/test.yaml
diff --git a/testdata/projects/local_action_empty/workflows/test.yaml b/testdata/projects/local_action_empty/.github/workflows/test.yaml
similarity index 100%
rename from testdata/projects/local_action_empty/workflows/test.yaml
rename to testdata/projects/local_action_empty/.github/workflows/test.yaml
diff --git a/testdata/projects/recursive_workflow_call/workflows/recursive.yaml b/testdata/projects/recursive_workflow_call/.github/workflows/recursive.yaml
similarity index 91%
rename from testdata/projects/recursive_workflow_call/workflows/recursive.yaml
rename to testdata/projects/recursive_workflow_call/.github/workflows/recursive.yaml
index b2168cf4e..adf66ebb1 100644
--- a/testdata/projects/recursive_workflow_call/workflows/recursive.yaml
+++ b/testdata/projects/recursive_workflow_call/.github/workflows/recursive.yaml
@@ -16,7 +16,7 @@ on:
 
 jobs:
   caller:
-    uses: ./workflows/recursive.yaml
+    uses: ./.github/workflows/recursive.yaml
     with:
       input1: hello
       input2: 42
diff --git a/testdata/projects/user_defined_runner_label/actionlint.yaml b/testdata/projects/user_defined_runner_label/.github/actionlint.yaml
similarity index 100%
rename from testdata/projects/user_defined_runner_label/actionlint.yaml
rename to testdata/projects/user_defined_runner_label/.github/actionlint.yaml
diff --git a/testdata/projects/user_defined_runner_label/workflows/test.yaml b/testdata/projects/user_defined_runner_label/.github/workflows/test.yaml
similarity index 100%
rename from testdata/projects/user_defined_runner_label/workflows/test.yaml
rename to testdata/projects/user_defined_runner_label/.github/workflows/test.yaml
diff --git a/testdata/projects/workflow_call_inherit_secrets/workflows/reusable.yaml b/testdata/projects/workflow_call_inherit_secrets/.github/workflows/reusable.yaml
similarity index 100%
rename from testdata/projects/workflow_call_inherit_secrets/workflows/reusable.yaml
rename to testdata/projects/workflow_call_inherit_secrets/.github/workflows/reusable.yaml
diff --git a/testdata/projects/workflow_call_inherit_secrets/workflows/test.yaml b/testdata/projects/workflow_call_inherit_secrets/.github/workflows/test.yaml
similarity index 51%
rename from testdata/projects/workflow_call_inherit_secrets/workflows/test.yaml
rename to testdata/projects/workflow_call_inherit_secrets/.github/workflows/test.yaml
index bcee02df4..06ee8c94e 100644
--- a/testdata/projects/workflow_call_inherit_secrets/workflows/test.yaml
+++ b/testdata/projects/workflow_call_inherit_secrets/.github/workflows/test.yaml
@@ -2,5 +2,5 @@ on: push
 
 jobs:
   caller:
-    uses: ./workflows/reusable.yaml
+    uses: ./.github/workflows/reusable.yaml
     secrets: inherit
diff --git a/testdata/projects/workflow_call_input_type_check.out b/testdata/projects/workflow_call_input_type_check.out
index bdc0e7e33..f12212dc4 100644
--- a/testdata/projects/workflow_call_input_type_check.out
+++ b/testdata/projects/workflow_call_input_type_check.out
@@ -1,6 +1,6 @@
-workflows/reusable.yaml:10:7: "type" is missing at "broken_input" input of workflow_call event [syntax-check]
-workflows/test.yaml:8:18: input "str_input" is typed as string by reusable workflow "./workflows/reusable.yaml". null value cannot be assigned [expression]
-workflows/test.yaml:9:18: input "num_input" is typed as number by reusable workflow "./workflows/reusable.yaml". bool value cannot be assigned [expression]
-workflows/test.yaml:15:18: input "str_input" is typed as string by reusable workflow "./workflows/reusable.yaml". bool value cannot be assigned [expression]
-workflows/test.yaml:16:18: input "num_input" is typed as number by reusable workflow "./workflows/reusable.yaml". string value cannot be assigned [expression]
-workflows/test.yaml:22:17: input "num_input" is typed as number by reusable workflow "./workflows/reusable.yaml". string value cannot be assigned [expression]
+.github/workflows/reusable.yaml:10:7: "type" is missing at "broken_input" input of workflow_call event [syntax-check]
+.github/workflows/test.yaml:8:18: input "str_input" is typed as string by reusable workflow "./.github/workflows/reusable.yaml". null value cannot be assigned [expression]
+.github/workflows/test.yaml:9:18: input "num_input" is typed as number by reusable workflow "./.github/workflows/reusable.yaml". bool value cannot be assigned [expression]
+.github/workflows/test.yaml:15:18: input "str_input" is typed as string by reusable workflow "./.github/workflows/reusable.yaml". bool value cannot be assigned [expression]
+.github/workflows/test.yaml:16:18: input "num_input" is typed as number by reusable workflow "./.github/workflows/reusable.yaml". string value cannot be assigned [expression]
+.github/workflows/test.yaml:22:17: input "num_input" is typed as number by reusable workflow "./.github/workflows/reusable.yaml". string value cannot be assigned [expression]
diff --git a/testdata/projects/workflow_call_input_type_check/workflows/reusable.yaml b/testdata/projects/workflow_call_input_type_check/.github/workflows/reusable.yaml
similarity index 100%
rename from testdata/projects/workflow_call_input_type_check/workflows/reusable.yaml
rename to testdata/projects/workflow_call_input_type_check/.github/workflows/reusable.yaml
diff --git a/testdata/projects/workflow_call_input_type_check/workflows/test.yaml b/testdata/projects/workflow_call_input_type_check/.github/workflows/test.yaml
similarity index 73%
rename from testdata/projects/workflow_call_input_type_check/workflows/test.yaml
rename to testdata/projects/workflow_call_input_type_check/.github/workflows/test.yaml
index e2fa31ed5..c01ac5ddd 100644
--- a/testdata/projects/workflow_call_input_type_check/workflows/test.yaml
+++ b/testdata/projects/workflow_call_input_type_check/.github/workflows/test.yaml
@@ -2,7 +2,7 @@ on: push
 
 jobs:
   caller1:
-    uses: ./workflows/reusable.yaml
+    uses: ./.github/workflows/reusable.yaml
     with:
       # Note: any value can be converted into bool
       str_input: null
@@ -10,13 +10,13 @@ jobs:
       bool_input: 'foo!'
       broken_input: null
   caller2:
-    uses: ./workflows/reusable.yaml
+    uses: ./.github/workflows/reusable.yaml
     with:
       str_input: ${{ true }}
       num_input: ${{ 'foo' }}
       broken_input: 42
   caller3:
-    uses: ./workflows/reusable.yaml
+    uses: ./.github/workflows/reusable.yaml
     with:
       str_input:
       num_input:
diff --git a/testdata/projects/workflow_call_missing_required.out b/testdata/projects/workflow_call_missing_required.out
index b5bcb3951..179629dd2 100644
--- a/testdata/projects/workflow_call_missing_required.out
+++ b/testdata/projects/workflow_call_missing_required.out
@@ -1,2 +1,2 @@
-workflows/test.yaml:5:11: input "required1" is required by "./workflows/reusable.yaml" reusable workflow [workflow-call]
-workflows/test.yaml:5:11: secret "required1" is required by "./workflows/reusable.yaml" reusable workflow [workflow-call]
+.github/workflows/test.yaml:5:11: input "required1" is required by "./.github/workflows/reusable.yaml" reusable workflow [workflow-call]
+.github/workflows/test.yaml:5:11: secret "required1" is required by "./.github/workflows/reusable.yaml" reusable workflow [workflow-call]
diff --git a/testdata/projects/workflow_call_missing_required/workflows/reusable.yaml b/testdata/projects/workflow_call_missing_required/.github/workflows/reusable.yaml
similarity index 100%
rename from testdata/projects/workflow_call_missing_required/workflows/reusable.yaml
rename to testdata/projects/workflow_call_missing_required/.github/workflows/reusable.yaml
diff --git a/testdata/projects/workflow_call_missing_required/.github/workflows/test.yaml b/testdata/projects/workflow_call_missing_required/.github/workflows/test.yaml
new file mode 100644
index 000000000..a62fe9da5
--- /dev/null
+++ b/testdata/projects/workflow_call_missing_required/.github/workflows/test.yaml
@@ -0,0 +1,5 @@
+on: push
+
+jobs:
+  caller:
+    uses: ./.github/workflows/reusable.yaml
diff --git a/testdata/projects/workflow_call_missing_required/workflows/test.yaml b/testdata/projects/workflow_call_missing_required/workflows/test.yaml
deleted file mode 100644
index d25f6e5fd..000000000
--- a/testdata/projects/workflow_call_missing_required/workflows/test.yaml
+++ /dev/null
@@ -1,5 +0,0 @@
-on: push
-
-jobs:
-  caller:
-    uses: ./workflows/reusable.yaml
diff --git a/testdata/projects/workflow_call_not_found.out b/testdata/projects/workflow_call_not_found.out
index 27bc88161..58f2aee12 100644
--- a/testdata/projects/workflow_call_not_found.out
+++ b/testdata/projects/workflow_call_not_found.out
@@ -1 +1 @@
-/workflows/test\.yaml:5:11: could not read reusable workflow file for "\./workflows/this-workflow-does-not-exist\.yaml": .+ \[(expression|workflow-call)\]/
+/workflows/test\.yaml:5:11: could not read reusable workflow file for "\./.github/workflows/this-workflow-does-not-exist\.yaml": .+ \[(expression|workflow-call)\]/
diff --git a/testdata/projects/workflow_call_not_found/workflows/test.yaml b/testdata/projects/workflow_call_not_found/.github/workflows/test.yaml
similarity index 71%
rename from testdata/projects/workflow_call_not_found/workflows/test.yaml
rename to testdata/projects/workflow_call_not_found/.github/workflows/test.yaml
index 7f9652e32..15651e47c 100644
--- a/testdata/projects/workflow_call_not_found/workflows/test.yaml
+++ b/testdata/projects/workflow_call_not_found/.github/workflows/test.yaml
@@ -2,7 +2,7 @@ on: push
 
 jobs:
   caller:
-    uses: ./workflows/this-workflow-does-not-exist.yaml
+    uses: ./.github/workflows/this-workflow-does-not-exist.yaml
   other:
     needs: [caller]
     runs-on: ubuntu-latest
diff --git a/testdata/projects/workflow_call_ok/workflows/empty1.yaml b/testdata/projects/workflow_call_ok/.github/workflows/empty1.yaml
similarity index 100%
rename from testdata/projects/workflow_call_ok/workflows/empty1.yaml
rename to testdata/projects/workflow_call_ok/.github/workflows/empty1.yaml
diff --git a/testdata/projects/workflow_call_ok/workflows/empty2.yaml b/testdata/projects/workflow_call_ok/.github/workflows/empty2.yaml
similarity index 100%
rename from testdata/projects/workflow_call_ok/workflows/empty2.yaml
rename to testdata/projects/workflow_call_ok/.github/workflows/empty2.yaml
diff --git a/testdata/projects/workflow_call_ok/workflows/empty3.yaml b/testdata/projects/workflow_call_ok/.github/workflows/empty3.yaml
similarity index 100%
rename from testdata/projects/workflow_call_ok/workflows/empty3.yaml
rename to testdata/projects/workflow_call_ok/.github/workflows/empty3.yaml
diff --git a/testdata/projects/workflow_call_ok/workflows/reusable_all_optional.yaml b/testdata/projects/workflow_call_ok/.github/workflows/reusable_all_optional.yaml
similarity index 100%
rename from testdata/projects/workflow_call_ok/workflows/reusable_all_optional.yaml
rename to testdata/projects/workflow_call_ok/.github/workflows/reusable_all_optional.yaml
diff --git a/testdata/projects/workflow_call_ok/workflows/reusable_all_required.yaml b/testdata/projects/workflow_call_ok/.github/workflows/reusable_all_required.yaml
similarity index 100%
rename from testdata/projects/workflow_call_ok/workflows/reusable_all_required.yaml
rename to testdata/projects/workflow_call_ok/.github/workflows/reusable_all_required.yaml
diff --git a/testdata/projects/workflow_call_ok/workflows/test.yaml b/testdata/projects/workflow_call_ok/.github/workflows/test.yaml
similarity index 52%
rename from testdata/projects/workflow_call_ok/workflows/test.yaml
rename to testdata/projects/workflow_call_ok/.github/workflows/test.yaml
index 975ed1b40..c032d8b58 100644
--- a/testdata/projects/workflow_call_ok/workflows/test.yaml
+++ b/testdata/projects/workflow_call_ok/.github/workflows/test.yaml
@@ -2,7 +2,7 @@ on: push
 
 jobs:
   caller1:
-    uses: ./workflows/reusable_all_required.yaml
+    uses: ./.github/workflows/reusable_all_required.yaml
     with:
       str: hi
       num: 13
@@ -10,7 +10,7 @@ jobs:
     secrets:
       foo: bar
   caller2:
-    uses: ./workflows/reusable_all_optional.yaml
+    uses: ./.github/workflows/reusable_all_optional.yaml
     with:
       str: hi
       num: 13
@@ -18,15 +18,15 @@ jobs:
     secrets:
       foo: bar
   caller3:
-    uses: ./workflows/reusable_all_optional.yaml
+    uses: ./.github/workflows/reusable_all_optional.yaml
   caller4:
-    uses: ./workflows/empty1.yaml
+    uses: ./.github/workflows/empty1.yaml
   caller5:
-    uses: ./workflows/empty2.yaml
+    uses: ./.github/workflows/empty2.yaml
   caller6:
-    uses: ./workflows/empty3.yaml
+    uses: ./.github/workflows/empty3.yaml
   pass-through-placeholder:
-    uses: ./workflows/reusable_all_required.yaml
+    uses: ./.github/workflows/reusable_all_required.yaml
     with:
       str: ${{ 'hi' }}
       num: ${{ 13 }}
diff --git a/testdata/projects/workflow_call_undefined.out b/testdata/projects/workflow_call_undefined.out
index bd0637a99..bf00a9ff5 100644
--- a/testdata/projects/workflow_call_undefined.out
+++ b/testdata/projects/workflow_call_undefined.out
@@ -1,5 +1,5 @@
-workflows/test.yaml:7:7: input "aaa" is not defined in "./workflows/reusable.yaml" reusable workflow. defined input is "foo" [workflow-call]
-workflows/test.yaml:10:7: secret "bbb" is not defined in "./workflows/reusable.yaml" reusable workflow. defined secret is "piyo" [workflow-call]
-workflows/test.yaml:17:24: property "ccc" is not defined in object type {bar: string} [expression]
-workflows/test.yaml:21:7: input "input1" is not defined in "./workflows/empty_reusable.yaml" reusable workflow. no input is defined [workflow-call]
-workflows/test.yaml:23:7: secret "secret1" is not defined in "./workflows/empty_reusable.yaml" reusable workflow. no secret is defined [workflow-call]
+.github/workflows/test.yaml:7:7: input "aaa" is not defined in "./.github/workflows/reusable.yaml" reusable workflow. defined input is "foo" [workflow-call]
+.github/workflows/test.yaml:10:7: secret "bbb" is not defined in "./.github/workflows/reusable.yaml" reusable workflow. defined secret is "piyo" [workflow-call]
+.github/workflows/test.yaml:17:24: property "ccc" is not defined in object type {bar: string} [expression]
+.github/workflows/test.yaml:21:7: input "input1" is not defined in "./.github/workflows/empty_reusable.yaml" reusable workflow. no input is defined [workflow-call]
+.github/workflows/test.yaml:23:7: secret "secret1" is not defined in "./.github/workflows/empty_reusable.yaml" reusable workflow. no secret is defined [workflow-call]
diff --git a/testdata/projects/workflow_call_undefined/workflows/empty_reusable.yaml b/testdata/projects/workflow_call_undefined/.github/workflows/empty_reusable.yaml
similarity index 100%
rename from testdata/projects/workflow_call_undefined/workflows/empty_reusable.yaml
rename to testdata/projects/workflow_call_undefined/.github/workflows/empty_reusable.yaml
diff --git a/testdata/projects/workflow_call_undefined/workflows/reusable.yaml b/testdata/projects/workflow_call_undefined/.github/workflows/reusable.yaml
similarity index 100%
rename from testdata/projects/workflow_call_undefined/workflows/reusable.yaml
rename to testdata/projects/workflow_call_undefined/.github/workflows/reusable.yaml
diff --git a/testdata/projects/workflow_call_undefined/workflows/test.yaml b/testdata/projects/workflow_call_undefined/.github/workflows/test.yaml
similarity index 83%
rename from testdata/projects/workflow_call_undefined/workflows/test.yaml
rename to testdata/projects/workflow_call_undefined/.github/workflows/test.yaml
index f385c99d9..6b0692324 100644
--- a/testdata/projects/workflow_call_undefined/workflows/test.yaml
+++ b/testdata/projects/workflow_call_undefined/.github/workflows/test.yaml
@@ -2,7 +2,7 @@ on: push
 
 jobs:
   caller:
-    uses: ./workflows/reusable.yaml
+    uses: ./.github/workflows/reusable.yaml
     with:
       aaa: this is not existing
       foo: this is existing
@@ -16,7 +16,7 @@ jobs:
       - run: echo '${{ needs.caller.outputs.bar }} is existing'
       - run: echo '${{ needs.caller.outputs.ccc }} is not existing'
   empty:
-    uses: ./workflows/empty_reusable.yaml
+    uses: ./.github/workflows/empty_reusable.yaml
     with:
       input1: this is not existing
     secrets:
diff --git a/testdata/projects/workflow_call_upper_case.out b/testdata/projects/workflow_call_upper_case.out
index 4e56a06f0..3cac4ef4f 100644
--- a/testdata/projects/workflow_call_upper_case.out
+++ b/testdata/projects/workflow_call_upper_case.out
@@ -1,10 +1,10 @@
-workflows/missing.yaml:5:11: input "MY_INPUT_2" is required by "./reusable/upper.yaml" reusable workflow [workflow-call]
-workflows/missing.yaml:5:11: secret "MY_SECRET_2" is required by "./reusable/upper.yaml" reusable workflow [workflow-call]
-workflows/output.yaml:32:30: property "my_output_3" is not defined in object type {my_output_1: string; my_output_2: string} [expression]
-workflows/output.yaml:33:30: property "my_output_3" is not defined in object type {my_output_1: string; my_output_2: string} [expression]
-workflows/output.yaml:34:30: property "my_output_3" is not defined in object type {my_output_1: string; my_output_2: string} [expression]
-workflows/output.yaml:35:30: property "my_output_3" is not defined in object type {my_output_1: string; my_output_2: string} [expression]
-workflows/undefined.yaml:9:7: input "MY_INPUT_3" is not defined in "./reusable/upper.yaml" reusable workflow. defined inputs are "MY_INPUT_1", "MY_INPUT_2" [workflow-call]
-workflows/undefined.yaml:13:7: secret "MY_SECRET_3" is not defined in "./reusable/upper.yaml" reusable workflow. defined secrets are "MY_SECRET_1", "MY_SECRET_2" [workflow-call]
-workflows/undefined.yaml:19:7: input "MY_INPUT_3" is not defined in "./reusable/lower.yaml" reusable workflow. defined inputs are "my_input_1", "my_input_2" [workflow-call]
-workflows/undefined.yaml:23:7: secret "MY_SECRET_3" is not defined in "./reusable/lower.yaml" reusable workflow. defined secrets are "my_secret_1", "my_secret_2" [workflow-call]
+.github/workflows/missing.yaml:5:11: input "MY_INPUT_2" is required by "./reusable/upper.yaml" reusable workflow [workflow-call]
+.github/workflows/missing.yaml:5:11: secret "MY_SECRET_2" is required by "./reusable/upper.yaml" reusable workflow [workflow-call]
+.github/workflows/output.yaml:32:30: property "my_output_3" is not defined in object type {my_output_1: string; my_output_2: string} [expression]
+.github/workflows/output.yaml:33:30: property "my_output_3" is not defined in object type {my_output_1: string; my_output_2: string} [expression]
+.github/workflows/output.yaml:34:30: property "my_output_3" is not defined in object type {my_output_1: string; my_output_2: string} [expression]
+.github/workflows/output.yaml:35:30: property "my_output_3" is not defined in object type {my_output_1: string; my_output_2: string} [expression]
+.github/workflows/undefined.yaml:9:7: input "MY_INPUT_3" is not defined in "./reusable/upper.yaml" reusable workflow. defined inputs are "MY_INPUT_1", "MY_INPUT_2" [workflow-call]
+.github/workflows/undefined.yaml:13:7: secret "MY_SECRET_3" is not defined in "./reusable/upper.yaml" reusable workflow. defined secrets are "MY_SECRET_1", "MY_SECRET_2" [workflow-call]
+.github/workflows/undefined.yaml:19:7: input "MY_INPUT_3" is not defined in "./reusable/lower.yaml" reusable workflow. defined inputs are "my_input_1", "my_input_2" [workflow-call]
+.github/workflows/undefined.yaml:23:7: secret "MY_SECRET_3" is not defined in "./reusable/lower.yaml" reusable workflow. defined secrets are "my_secret_1", "my_secret_2" [workflow-call]
diff --git a/testdata/projects/workflow_call_upper_case/workflows/missing.yaml b/testdata/projects/workflow_call_upper_case/.github/workflows/missing.yaml
similarity index 100%
rename from testdata/projects/workflow_call_upper_case/workflows/missing.yaml
rename to testdata/projects/workflow_call_upper_case/.github/workflows/missing.yaml
diff --git a/testdata/projects/workflow_call_upper_case/workflows/ok_lower.yaml b/testdata/projects/workflow_call_upper_case/.github/workflows/ok_lower.yaml
similarity index 100%
rename from testdata/projects/workflow_call_upper_case/workflows/ok_lower.yaml
rename to testdata/projects/workflow_call_upper_case/.github/workflows/ok_lower.yaml
diff --git a/testdata/projects/workflow_call_upper_case/workflows/ok_upper.yaml b/testdata/projects/workflow_call_upper_case/.github/workflows/ok_upper.yaml
similarity index 100%
rename from testdata/projects/workflow_call_upper_case/workflows/ok_upper.yaml
rename to testdata/projects/workflow_call_upper_case/.github/workflows/ok_upper.yaml
diff --git a/testdata/projects/workflow_call_upper_case/workflows/output.yaml b/testdata/projects/workflow_call_upper_case/.github/workflows/output.yaml
similarity index 100%
rename from testdata/projects/workflow_call_upper_case/workflows/output.yaml
rename to testdata/projects/workflow_call_upper_case/.github/workflows/output.yaml
diff --git a/testdata/projects/workflow_call_upper_case/workflows/undefined.yaml b/testdata/projects/workflow_call_upper_case/.github/workflows/undefined.yaml
similarity index 100%
rename from testdata/projects/workflow_call_upper_case/workflows/undefined.yaml
rename to testdata/projects/workflow_call_upper_case/.github/workflows/undefined.yaml