fix: re-fetch cached reusable workflow on every run (#930)

`cloneIfRequired` only ran the underlying clone executor when the target directory was missing, so a reusable workflow referenced by a moving ref (`uses: org/repo/.gitea/workflows/wf.yml@master`) was cached forever after the first invocation — edits to the source file never propagated.

Always invoke `git.NewGitCloneExecutor`. It handles existing repositories via fetch + pull + hard-reset, so branch and tag refs are brought up to date on each run, matching GitHub Actions semantics.

Drops the global `executorLock` too: `NewGitCloneExecutor` already takes a per-directory lock via `acquireCloneLock`, so the outer mutex only added unnecessary serialization across unrelated reusable-workflow clones — worse now that every invocation runs the full fetch.

Includes a regression test that drives the wrapper against a local bare repo, pushes a new commit on `master` between two invocations, and asserts the cached workflow file reflects the new tip.

Fixes: https://github.com/go-gitea/gitea/issues/37483
Fixes: https://gitea.com/gitea/runner/issues/726
Related: https://github.com/go-gitea/gitea/issues/30543

Would be subsumed by https://gitea.com/gitea/runner/pulls/814 ("WIP: Introduce new action cache") once that lands.

---
This PR was written with the help of Claude Opus 4.7

Reviewed-on: https://gitea.com/gitea/runner/pulls/930
Reviewed-by: Zettat123 <39446+zettat123@noreply.gitea.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-committed-by: silverwind <me@silverwind.io>

act/runner/reusable_workflow.go

@@ -7,15 +7,11 @@ package runner
 import (
 	"archive/tar"
 	"context"
-	"errors"
 	"fmt"
-	"io/fs"
 	"net/url"
-	"os"
 	"path"
 	"regexp"
 	"strings"
-	"sync"
 
 	"gitea.com/gitea/runner/act/common"
 	"gitea.com/gitea/runner/act/common/git"
@@ -51,7 +47,7 @@ func newLocalReusableWorkflowExecutor(rc *RunContext) common.Executor {
 	token := rc.Config.GetToken()
 
 	return common.NewPipelineExecutor(
-		newMutexExecutor(cloneIfRequired(rc, *remoteReusableWorkflow, workflowDir, token)),
+		cloneRemoteReusableWorkflow(rc, remoteReusableWorkflow.CloneURL(), remoteReusableWorkflow.Ref, workflowDir, token),
 		newReusableWorkflowExecutor(rc, workflowDir, remoteReusableWorkflow.FilePath()),
 	)
 }
@@ -85,7 +81,7 @@ func newRemoteReusableWorkflowExecutor(rc *RunContext) common.Executor {
 	token := getGitCloneToken(rc.Config, remoteReusableWorkflow.CloneURL())
 
 	return common.NewPipelineExecutor(
-		newMutexExecutor(cloneIfRequired(rc, *remoteReusableWorkflow, workflowDir, token)),
+		cloneRemoteReusableWorkflow(rc, remoteReusableWorkflow.CloneURL(), remoteReusableWorkflow.Ref, workflowDir, token),
 		newReusableWorkflowExecutor(rc, workflowDir, remoteReusableWorkflow.FilePath()),
 	)
 }
@@ -125,43 +121,27 @@ func newActionCacheReusableWorkflowExecutor(rc *RunContext, filename string, rem
 	}
 }
 
-var executorLock sync.Mutex
-
-func newMutexExecutor(executor common.Executor) common.Executor {
+// cloneRemoteReusableWorkflow always invokes the clone executor — moving refs
+// (branches, tags) must be re-resolved each run, matching GitHub Actions.
+//
+// Callers must not change remoteReusableWorkflow.URL, because:
+//  1. Gitea doesn't support specifying GithubContext.ServerURL by the GITHUB_SERVER_URL env
+//  2. Gitea has already full URL with rc.Config.GitHubInstance when calling newRemoteReusableWorkflowWithPlat
+//
+// remoteReusableWorkflow.URL = rc.getGithubContext(ctx).ServerURL
+func cloneRemoteReusableWorkflow(rc *RunContext, cloneURL, ref, targetDirectory, token string) common.Executor {
 	return func(ctx context.Context) error {
-		executorLock.Lock()
-		defer executorLock.Unlock()
-
-		return executor(ctx)
+		cloneURL = rc.NewExpressionEvaluator(ctx).Interpolate(ctx, cloneURL)
+		return git.NewGitCloneExecutor(git.NewGitCloneExecutorInput{
+			URL:         cloneURL,
+			Ref:         ref,
+			Dir:         targetDirectory,
+			Token:       token,
+			OfflineMode: rc.Config.ActionOfflineMode,
+		})(ctx)
 	}
 }
 
-func cloneIfRequired(rc *RunContext, remoteReusableWorkflow remoteReusableWorkflow, targetDirectory, token string) common.Executor {
-	return common.NewConditionalExecutor(
-		func(ctx context.Context) bool {
-			_, err := os.Stat(targetDirectory)
-			notExists := errors.Is(err, fs.ErrNotExist)
-			return notExists
-		},
-		func(ctx context.Context) error {
-			// interpolate the cloneURL
-			cloneURL := rc.NewExpressionEvaluator(ctx).Interpolate(ctx, remoteReusableWorkflow.CloneURL())
-			// Do not change the remoteReusableWorkflow.URL, because:
-			// 	1. Gitea doesn't support specifying GithubContext.ServerURL by the GITHUB_SERVER_URL env
-			//	2. Gitea has already full URL with rc.Config.GitHubInstance when calling newRemoteReusableWorkflowWithPlat
-			// remoteReusableWorkflow.URL = rc.getGithubContext(ctx).ServerURL
-			return git.NewGitCloneExecutor(git.NewGitCloneExecutorInput{
-				URL:         cloneURL,
-				Ref:         remoteReusableWorkflow.Ref,
-				Dir:         targetDirectory,
-				Token:       token,
-				OfflineMode: rc.Config.ActionOfflineMode,
-			})(ctx)
-		},
-		nil,
-	)
-}
-
 func newReusableWorkflowExecutor(rc *RunContext, directory, workflow string) common.Executor {
 	return func(ctx context.Context) error {
 		planner, err := model.NewWorkflowPlanner(path.Join(directory, workflow), true)

act/runner/reusable_workflow_test.go

@@ -0,0 +1,82 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package runner
+
+import (
+	"context"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+
+	"gitea.com/gitea/runner/act/model"
+
+	"github.com/stretchr/testify/require"
+)
+
+// Regression test for go-gitea/gitea#37483: a remote reusable workflow at a moving
+// ref (branch/tag) must reflect the new tip on every invocation, not stay pinned
+// to the cache populated on the first run.
+func TestReusableWorkflowCachedBranchRefRefreshes(t *testing.T) {
+	if _, err := exec.LookPath("git"); err != nil {
+		t.Skip("git not available in PATH")
+	}
+
+	remoteDir := t.TempDir()
+	gitMust(t, "", "init", "--bare", "--initial-branch=master", remoteDir)
+
+	workDir := t.TempDir()
+	gitMust(t, "", "clone", remoteDir, workDir)
+	gitMust(t, workDir, "config", "user.email", "test@test")
+	gitMust(t, workDir, "config", "user.name", "test")
+	gitMust(t, workDir, "checkout", "-b", "master")
+
+	const workflowPath = ".gitea/workflows/reusable.yml"
+	tmpl := func(tag string) string {
+		return "name: reusable\non:\n  workflow_call:\njobs:\n  build:\n    runs-on: ubuntu-latest\n    steps:\n      - run: echo " + tag + "\n"
+	}
+
+	require.NoError(t, os.MkdirAll(filepath.Join(workDir, ".gitea/workflows"), 0o755))
+	require.NoError(t, os.WriteFile(filepath.Join(workDir, workflowPath), []byte(tmpl("v1")), 0o644))
+	gitMust(t, workDir, "add", workflowPath)
+	gitMust(t, workDir, "commit", "-m", "v1")
+	gitMust(t, workDir, "push", "-u", "origin", "master")
+
+	rc := &RunContext{
+		Config: &Config{},
+		Run: &model.Run{
+			JobID: "j1",
+			Workflow: &model.Workflow{
+				Name: "wf",
+				Jobs: map[string]*model.Job{"j1": {}},
+			},
+		},
+	}
+	cacheDir := t.TempDir()
+
+	require.NoError(t, cloneRemoteReusableWorkflow(rc, remoteDir, "master", cacheDir, "")(context.Background()))
+	got, err := os.ReadFile(filepath.Join(cacheDir, workflowPath))
+	require.NoError(t, err)
+	require.Equal(t, tmpl("v1"), string(got))
+
+	// Branch tip moves; cache key (cacheDir) does not.
+	require.NoError(t, os.WriteFile(filepath.Join(workDir, workflowPath), []byte(tmpl("v2")), 0o644))
+	gitMust(t, workDir, "commit", "-am", "v2")
+	gitMust(t, workDir, "push", "origin", "master")
+
+	require.NoError(t, cloneRemoteReusableWorkflow(rc, remoteDir, "master", cacheDir, "")(context.Background()))
+	got, err = os.ReadFile(filepath.Join(cacheDir, workflowPath))
+	require.NoError(t, err)
+	require.Equal(t, tmpl("v2"), string(got), "cached workflow file must reflect the updated branch tip")
+}
+
+func gitMust(t *testing.T, dir string, args ...string) {
+	t.Helper()
+	cmd := exec.Command("git", args...)
+	if dir != "" {
+		cmd.Dir = dir
+	}
+	out, err := cmd.CombinedOutput()
+	require.NoError(t, err, "git %v: %s", args, string(out))
+}