enhance: test on Windows and fix what it found (#1348)

Adds a weekly and on-demand workflow that runs the cross-compiled tests on Windows Server 2025 Core in a [dockur/windows](https://github.com/dockur/windows) QEMU VM, and fixes the Windows bugs it found in host and UNC paths, env handling, shell quoting, post-task scripts, health checks, checkout, action symlinks, step summaries, Git client certificates and docker mode from a Windows host.

Host-mode steps now emit UTF-8, `bash` falls back to Git's bash instead of the WSL launcher, the runner can run as a native Windows service, steps can keep background helpers with `RUNNER_TRACKING_ID`, and Windows arm64 binaries are released.

Fixes: https://gitea.com/gitea/runner/issues/1339
Fixes: https://gitea.com/gitea/runner/issues/637
Fixes: https://gitea.com/gitea/runner/issues/1172
Fixes: https://gitea.com/gitea/runner/issues/347
Reviewed-on: https://gitea.com/gitea/runner/pulls/1348
Reviewed-by: bircni <bircni@icloud.com>

.gitea/workflows/test-windows.yml

@@ -0,0 +1,21 @@
+name: windows
+on:
+  schedule:
+    - cron: '0 3 * * 1'
+  workflow_dispatch:
+
+env:
+  DOCKER_CONFIG: /tmp/docker-noauth # see test.yml
+
+jobs:
+  test:
+    name: test on windows
+    runs-on: ubuntu-latest
+    timeout-minutes: 180
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
+      - uses: ./.gitea/actions/go-setup
+      - name: prepare anonymous docker config
+        run: mkdir -p "$DOCKER_CONFIG" && echo '{}' > "$DOCKER_CONFIG/config.json"
+      - name: test on windows
+        run: make test-windows

.goreleaser.yaml

@@ -34,8 +34,6 @@ builds:
       goarch: s390x
     - goos: windows
       goarch: arm
-    - goos: windows
-      goarch: arm64
     - goos: freebsd
       goarch: s390x
     - goos: freebsd

DEVELOPMENT.md

@@ -69,3 +69,12 @@ Docker and Kubernetes.
 
 The suite shares one Gitea, regular runner and k3s cluster. Cache and ephemeral scenarios use isolated
 repository runners. A run path is `<workflow>@<ref>` and a log row is `<timestamp>Z <payload>`.
+
+## Windows tests
+
+`make test-windows` cross-compiles the test binaries, installs Windows Server 2025 Core in a
+[dockur/windows](https://github.com/dockur/windows) QEMU VM on the docker host and runs them there.
+The host must be amd64 and allow privileged containers. `WINDOWS_TEST_TIMEOUT` sets the minutes
+allowed for installing Windows and running the tests, 165 by default. The VM uses KVM when the host
+has `/dev/kvm`, otherwise Windows is emulated and much slower. Docker-backed tests skip in the VM
+and the race detector is off, it needs cgo. CI runs this weekly and on demand.

Makefile

@@ -8,6 +8,7 @@ E2E_JOB_IMAGE ?= docker.gitea.com/runner-images:ubuntu-latest@sha256:657378e5cfd
 SERVICE_IMAGE ?= nginx:1.31.7-alpine@sha256:892bb2152464f0c5d8972593a5f5afaf8054552580b699d95f8ff4af08c2d33d # renovate: datasource=docker
 E2E_GITEA_IMAGE ?= gitea/gitea:main-nightly
 E2E_K3S_IMAGE ?= rancher/k3s:v1.37.1-k3s1@sha256:ca7f37d993d82ef0dcdcfecb2e0e2618ea541dbaffc620c8cedebe01a82acd0d # renovate: datasource=docker
+WINDOWS_TEST_IMAGE ?= dockurr/windows:6.06@sha256:16fd7c39a3e48bb946d29c59dc6015942e5b900a1fa5d7e5552053bfc48ee2ea # renovate: datasource=docker
 
 GOFILES := $(shell find . -type f -name "*.go" -o -name "go.mod" ! -name "generated.*")
 
@@ -150,6 +151,10 @@ coverage-report: ## turn coverage.txt from `make test` into .tmp/coverage.md
 test-dind: ## run the daemon-facing tests against the built dind image or podman (TARGET=dind|dind-rootless|podman)
 	@PODMAN_TEST_IMAGE=$(PODMAN_TEST_IMAGE) ./scripts/test-dind.sh $(TARGET)
 
+.PHONY: test-windows
+test-windows: ## run the tests on Windows Server Core in a QEMU VM on the docker host
+	@WINDOWS_TEST_IMAGE=$(WINDOWS_TEST_IMAGE) ./scripts/test-windows.sh
+
 E2E_CONCURRENCY ?= 8
 
 .PHONY: test-e2e

README.md

@@ -2,6 +2,8 @@
 
 ## Installation
 
+The runner runs on Linux, macOS and Windows.
+
 ### Prerequisites
 
 On the runner:
@@ -89,6 +91,23 @@ If the registry succeed, it will run immediately. Next time, you could run the r
 ./gitea-runner daemon
 ```
 
+### Windows service
+
+Register the runner first, keeping `gitea-runner.exe`, `config.yaml` and the `.runner` registration file in the same directory. From an elevated Command Prompt, install and start the service with absolute paths:
+
+```bat
+sc.exe create gitea-runner binPath= "\"C:\gitea-runner\gitea-runner.exe\" daemon --config \"C:\gitea-runner\config.yaml\"" start= auto
+sc.exe start gitea-runner
+```
+
+The service runs from the executable's directory and appends its logs to `gitea-runner.log` there. Its account needs write access to that directory and access to the tools used by jobs. Use `sc.exe stop gitea-runner` to stop it, allowing running jobs to finish according to `runner.shutdown_timeout`.
+
+On shutdown or reboot, Windows waits for the service's preshutdown timeout at most, so set it above `runner.shutdown_timeout`, here six minutes for `5m`. It takes effect after the next reboot:
+
+```bat
+reg.exe add HKLM\SYSTEM\CurrentControlSet\Services\gitea-runner /v PreshutdownTimeout /t REG_DWORD /d 360000 /f
+```
+
 ### Run with docker
 
 The recommended Docker-in-Docker image runs its own Docker daemon for jobs. Jobs never get the host's Docker socket, which is equivalent to root access on the host.
@@ -233,7 +252,9 @@ The `daemon` command also accepts `--labels` (which defaults to the `GITEA_RUNNE
 
 Whenever the resulting labels differ from the ones in the registration file, they are written back to it and re-declared to the Gitea instance on startup.
 
-> **Note:** A runner that only exposes `host` labels still needs access to a Docker daemon (e.g. a mounted `/var/run/docker.sock`) whenever a job uses a `docker://` action or a service container. `host` labels only change where the job's own steps run; container-based steps and actions are still executed with Docker.
+> **Note:** A runner that only exposes `host` labels still needs access to a Docker daemon (e.g. a mounted `/var/run/docker.sock`) whenever a job uses a `docker://` action or a service container. `host` labels only change where the job's own steps run; container-based steps and actions are still executed with Docker. Windows hosts do not support container actions and `docker://` steps in host jobs, like GitHub's Windows runners.
+
+On Windows hosts, a step's background processes end with the job unless it opts out, see [host-mode background processes](docs/host-mode.md).
 
 #### Service containers
 

act/artifacts/server_test.go

@@ -281,7 +281,7 @@ func TestSafeResolve(t *testing.T) {
 
 	for name, tc := range tests {
 		t.Run(name, func(t *testing.T) {
-			require.Equal(t, tc.want, safeResolve(baseDir, tc.input))
+			require.Equal(t, filepath.FromSlash(tc.want), safeResolve(baseDir, tc.input))
 		})
 	}
 }

act/common/git/fetch_action.go

@@ -10,6 +10,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"io"
 	"math/rand/v2"
 	"net"
@@ -29,6 +30,10 @@ import (
 
 var actionFetches sync.Map
 
+var symlink = (*os.Root).Symlink
+
+var symlinkFallback = runtime.GOOS == "windows"
+
 const treeSizes = ".sizes" // beside the tree rather than in it, which is copied into job containers as it is
 
 type treeFile struct {
@@ -229,6 +234,8 @@ func extractTree(ctx context.Context, archive io.Reader, dir string, strip bool)
 
 	sha := ""
 	sizes := map[string]int64{}
+	links := map[string]string{}
+	var deferred []string
 	reader := tar.NewReader(archive)
 	for {
 		header, err := reader.Next()
@@ -257,9 +264,8 @@ func extractTree(ctx context.Context, archive io.Reader, dir string, strip bool)
 		case tar.TypeReg:
 			sizes[name], err = writeTreeFile(root, name, header.Mode, reader)
 		case tar.TypeSymlink:
-			if err = root.Symlink(header.Linkname, name); err != nil && runtime.GOOS == "windows" {
-				sizes[name], err = writeTreeFile(root, name, 0, strings.NewReader(header.Linkname))
-			}
+			links[filepath.Clean(name)] = header.Linkname
+			deferred = append(deferred, filepath.Clean(name))
 		}
 		if err != nil {
 			return "", err
@@ -268,12 +274,166 @@ func extractTree(ctx context.Context, archive io.Reader, dir string, strip bool)
 	if !isFullObjectID(sha) {
 		return "", errors.New("the archive names no commit")
 	}
+	linksByParent := map[string][]string{}
+	if symlinkFallback {
+		for name := range links {
+			linksByParent[filepath.Dir(name)] = append(linksByParent[filepath.Dir(name)], filepath.Base(name))
+		}
+	}
+	for requireTarget := symlinkFallback; len(deferred) > 0; {
+		unresolved := deferred[:0]
+		for _, name := range deferred {
+			if err := ctx.Err(); err != nil {
+				return "", err
+			}
+			if requireTarget {
+				if _, err := root.Stat(filepath.Dir(name) + string(filepath.Separator) + links[name]); err != nil {
+					unresolved = append(unresolved, name)
+					continue
+				}
+			}
+			if err := symlink(root, links[name], name); err == nil || !symlinkFallback {
+				if err != nil {
+					return "", err
+				}
+				continue
+			}
+			if err := copyTreeLink(ctx, root, name, links, linksByParent, sizes); err != nil {
+				return "", fmt.Errorf("materialize symlink %q: %w", filepath.ToSlash(name), err)
+			}
+		}
+		if len(unresolved) == len(deferred) {
+			requireTarget = false
+		}
+		deferred = unresolved
+	}
 	if err := root.Close(); err != nil {
 		return "", err
 	}
 	return sha, installTree(ctx, dir, sha, temp, sizes)
 }
 
+func resolveTreeLink(name string, links map[string]string) (string, bool) {
+	if !filepath.IsLocal(name) {
+		return "", false
+	}
+	parts := strings.Split(name, string(filepath.Separator))
+	var resolved []string
+	for count := 0; len(parts) > 0; {
+		part := parts[0]
+		parts = parts[1:]
+		switch part {
+		case "", ".":
+			continue
+		case "..":
+			if len(resolved) == 0 {
+				return "", false
+			}
+			resolved = resolved[:len(resolved)-1]
+			continue
+		}
+		target, ok := links[filepath.Join(append(resolved, part)...)]
+		if !ok {
+			resolved = append(resolved, part)
+			continue
+		}
+		count++
+		if target == "" || os.IsPathSeparator(target[0]) || filepath.VolumeName(target) != "" || count > 255 {
+			return "", false
+		}
+		parts = append(strings.Split(filepath.FromSlash(target), string(filepath.Separator)), parts...)
+	}
+	return filepath.Join(append([]string{"."}, resolved...)...), true
+}
+
+var (
+	errTreeLinkTarget = errors.New("unmaterializable symlink target")
+	errTreeLinkCycle  = fmt.Errorf("cyclic %w", errTreeLinkTarget)
+)
+
+func copyTreeLink(ctx context.Context, root *os.Root, name string, links map[string]string, linksByParent map[string][]string, sizes map[string]int64) error {
+	writeLinkText := func(destination, target string) error { // as git writes links it cannot create
+		if err := root.RemoveAll(destination); err != nil {
+			return err
+		}
+		for written := range sizes {
+			if written == destination || strings.HasPrefix(written, destination+string(filepath.Separator)) {
+				delete(sizes, written)
+			}
+		}
+		size, err := writeTreeFile(root, destination, 0o644, strings.NewReader(target))
+		sizes[destination] = size
+		return err
+	}
+	active := map[string]bool{}
+	var copyTarget func(string, string) error
+	copyTarget = func(source, destination string) error {
+		if err := ctx.Err(); err != nil {
+			return err
+		}
+		source, ok := resolveTreeLink(source, links)
+		if !ok {
+			return errTreeLinkTarget
+		}
+		file, err := root.Open(source)
+		if err != nil {
+			if errors.Is(err, os.ErrNotExist) {
+				return errTreeLinkTarget
+			}
+			return err
+		}
+		defer file.Close()
+		info, err := file.Stat()
+		if err != nil {
+			return err
+		}
+		if info.Mode().IsRegular() {
+			sizes[destination], err = writeTreeFile(root, destination, int64(info.Mode().Perm()), file)
+			return err
+		}
+		if !info.IsDir() {
+			return errTreeLinkTarget
+		}
+		if active[source] {
+			return errTreeLinkCycle
+		}
+		active[source] = true
+		defer delete(active, source)
+		entries, err := file.ReadDir(-1)
+		if err != nil {
+			return err
+		}
+		children := map[string]bool{}
+		for _, entry := range entries {
+			children[entry.Name()] = true
+		}
+		for _, child := range linksByParent[source] {
+			children[child] = true
+		}
+		if err := root.MkdirAll(destination, info.Mode().Perm()); err != nil {
+			return err
+		}
+		for child := range children {
+			childSource, childDestination := filepath.Join(source, child), filepath.Join(destination, child)
+			err := copyTarget(childSource, childDestination)
+			if target, isLink := links[childSource]; isLink && errors.Is(err, errTreeLinkTarget) && !errors.Is(err, errTreeLinkCycle) {
+				err = writeLinkText(childDestination, target)
+			}
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+	if err := copyTarget(name, name); !errors.Is(err, errTreeLinkTarget) {
+		return err
+	}
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	return writeLinkText(name, links[name])
+}
+
 var lockTree = AcquireCloneLock // replaced in tests to see installTree wait for a job holding the tree
 
 // installTree moves temp into place as dir/sha, replacing a tree that failed treeIntact.

act/common/git/fetch_action_test.go

@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/base64"
+	"errors"
 	"fmt"
 	"net/http"
 	"net/http/cgi"
@@ -40,6 +41,7 @@ func TestFetchAction(t *testing.T) {
 	require.NoError(t, os.WriteFile(filepath.Join(remote, "run.sh"), []byte("#!/bin/sh\n"), 0o755))
 	require.NoError(t, os.Symlink("action.yml", filepath.Join(remote, "link")))
 	require.NoError(t, gitCmd("-C", remote, "add", "."))
+	require.NoError(t, gitCmd("-C", remote, "update-index", "--chmod=+x", "run.sh"))
 	require.NoError(t, gitCmd("-C", remote, "commit", "-m", "initial"))
 	require.NoError(t, gitCmd("-C", remote, "tag", "v1"))
 	expectedSha := gitRevParse(t, remote, "main")
@@ -192,7 +194,9 @@ func TestFetchAction(t *testing.T) {
 		assert.NoDirExists(t, filepath.Join(tree, ".git"))
 		info, err := os.Stat(filepath.Join(tree, "run.sh"))
 		require.NoError(t, err)
-		assert.Equal(t, os.FileMode(0o755), info.Mode().Perm())
+		if runtime.GOOS != "windows" {
+			assert.EqualValues(t, 0o755, info.Mode().Perm())
+		}
 		link, err := os.Readlink(filepath.Join(tree, "link"))
 		require.NoError(t, err)
 		assert.Equal(t, "action.yml", link)
@@ -391,6 +395,79 @@ func TestExtractTreeConfinesEntries(t *testing.T) {
 	}
 }
 
+func TestExtractTreeCopiesDeferredLinks(t *testing.T) {
+	originalSymlink, originalFallback := symlink, symlinkFallback
+	symlink = func(_root *os.Root, _target, _name string) error { return errors.New("symlink privilege unavailable") }
+	symlinkFallback = true
+	t.Cleanup(func() { symlink, symlinkFallback = originalSymlink, originalFallback })
+
+	for _, test := range []struct {
+		name  string
+		links [][2]string
+		files []string
+		text  bool
+	}{
+		{name: "file chain", links: [][2]string{{"index.js", "entry.js"}, {"entry.js", "dist/index.js"}}, files: []string{"index.js", "entry.js"}},
+		{name: "directory chain", links: [][2]string{{"lib", "bundle"}, {"bundle", "dist"}, {"dist/entry.js", "index.js"}}, files: []string{"lib/index.js", "lib/entry.js", "lib/nested/index.js", "bundle/index.js", "bundle/entry.js", "bundle/nested/index.js"}},
+		{name: "directory in target path", links: [][2]string{{"index.js", "bundle/nested/index.js"}, {"bundle", "dist"}}, files: []string{"index.js", "bundle/nested/index.js"}},
+		{name: "parent after directory link", links: [][2]string{{"index.js", "bundle/../index.js"}, {"bundle", "dist/nested"}}, files: []string{"index.js", "bundle/index.js"}},
+		{name: "outside", links: [][2]string{{"index.js", "../outside.js"}}, text: true},
+		{name: "absolute", links: [][2]string{{"index.js", t.TempDir()}}, text: true},
+		{name: "dangling", links: [][2]string{{"index.js", "missing.js"}}, text: true},
+		{name: "dangling child of directory link", links: [][2]string{{"lib", "dist"}, {"dist/optional", "missing.js"}}, files: []string{"lib/index.js", "lib/nested/index.js"}},
+		{name: "cycle", links: [][2]string{{"index.js", "entry.js"}, {"entry.js", "index.js"}}, text: true},
+		{name: "directory cycle", links: [][2]string{{"dist/loop", "."}}, text: true},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			sha := strings.Repeat("a", 40)
+			var archive bytes.Buffer
+			writer := tar.NewWriter(&archive)
+			require.NoError(t, writer.WriteHeader(&tar.Header{Typeflag: tar.TypeXGlobalHeader, PAXRecords: map[string]string{"comment": sha}}))
+			require.NoError(t, writer.WriteHeader(&tar.Header{Name: "dist", Typeflag: tar.TypeDir, Mode: 0o755}))
+			require.NoError(t, writer.WriteHeader(&tar.Header{Name: "dist/nested", Typeflag: tar.TypeDir, Mode: 0o755}))
+			for _, link := range test.links {
+				require.NoError(t, writer.WriteHeader(&tar.Header{Name: link[0], Typeflag: tar.TypeSymlink, Linkname: link[1]}))
+			}
+			content := "console.log('action');\n"
+			for _, name := range []string{"dist/index.js", "dist/nested/index.js"} {
+				require.NoError(t, writer.WriteHeader(&tar.Header{Name: name, Typeflag: tar.TypeReg, Mode: 0o755, Size: int64(len(content))}))
+				_, err := writer.Write([]byte(content))
+				require.NoError(t, err)
+			}
+			require.NoError(t, writer.Close())
+
+			dir := t.TempDir()
+			_, err := extractTree(t.Context(), &archive, dir, false)
+			require.NoError(t, err)
+			assert.True(t, treeIntact(dir, sha))
+			if test.text {
+				for _, link := range test.links {
+					data, err := os.ReadFile(filepath.Join(dir, sha, link[0]))
+					require.NoError(t, err)
+					assert.Equal(t, link[1], string(data))
+					info, err := os.Lstat(filepath.Join(dir, sha, link[0]))
+					require.NoError(t, err)
+					assert.True(t, info.Mode().IsRegular())
+				}
+			}
+			for _, name := range test.files {
+				data, err := os.ReadFile(filepath.Join(dir, sha, name))
+				require.NoError(t, err)
+				assert.Equal(t, content, string(data))
+				info, err := os.Lstat(filepath.Join(dir, sha, name))
+				require.NoError(t, err)
+				assert.True(t, info.Mode().IsRegular())
+				if runtime.GOOS != "windows" {
+					assert.Equal(t, os.FileMode(0o755), info.Mode().Perm())
+				}
+				require.NoError(t, os.WriteFile(filepath.Join(dir, sha, name), nil, 0o644))
+				assert.False(t, treeIntact(dir, sha), name)
+				require.NoError(t, os.WriteFile(filepath.Join(dir, sha, name), []byte(content), 0o755))
+			}
+		})
+	}
+}
+
 func TestTreeIntactFindsNamesThatAreNotUTF8(t *testing.T) {
 	if runtime.GOOS != "linux" {
 		t.Skip("macOS and Windows store no name that is not UTF-8")
@@ -410,3 +487,76 @@ func TestTreeIntactFindsNamesThatAreNotUTF8(t *testing.T) {
 	require.FileExists(t, filepath.Join(dir, sha, "caf\xe9.js"))
 	assert.True(t, treeIntact(dir, sha))
 }
+
+func TestExtractTreeCreatesLinksInPlatformOrder(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("requires symlink privileges")
+	}
+	original, originalFallback := symlink, symlinkFallback
+	var created []string
+	symlink = func(root *os.Root, target, name string) error {
+		created = append(created, name)
+		return root.Symlink(target, name)
+	}
+	t.Cleanup(func() { symlink, symlinkFallback = original, originalFallback })
+
+	var archive bytes.Buffer
+	writer := tar.NewWriter(&archive)
+	require.NoError(t, writer.WriteHeader(&tar.Header{Typeflag: tar.TypeXGlobalHeader, PAXRecords: map[string]string{"comment": strings.Repeat("a", 40)}}))
+	for _, entry := range []*tar.Header{
+		{Name: "a", Typeflag: tar.TypeSymlink, Linkname: "b"},
+		{Name: "b", Typeflag: tar.TypeSymlink, Linkname: "dist"},
+		{Name: "dangling", Typeflag: tar.TypeSymlink, Linkname: "missing"},
+		{Name: "dist", Typeflag: tar.TypeDir, Mode: 0o755},
+	} {
+		require.NoError(t, writer.WriteHeader(entry))
+	}
+	require.NoError(t, writer.Close())
+	for _, test := range []struct {
+		name     string
+		fallback bool
+		want     []string
+	}{
+		{name: "native", want: []string{"a", "b", "dangling"}},
+		{name: "fallback", fallback: true, want: []string{"b", "a", "dangling"}},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			symlinkFallback = test.fallback
+			created = nil
+			_, err := extractTree(t.Context(), bytes.NewReader(archive.Bytes()), t.TempDir(), false)
+			require.NoError(t, err)
+			assert.Equal(t, test.want, created)
+		})
+	}
+}
+
+func TestCopyTreeLinkCancellationBetweenEntries(t *testing.T) {
+	root, err := os.OpenRoot(t.TempDir())
+	require.NoError(t, err)
+	defer root.Close()
+	require.NoError(t, root.Mkdir("source", 0o755))
+	for _, name := range []string{"first", "second"} {
+		_, err := writeTreeFile(root, filepath.Join("source", name), 0o644, strings.NewReader("content"))
+		require.NoError(t, err)
+	}
+	sizes := map[string]int64{}
+	ctx, cancel := context.WithCancel(t.Context())
+	defer cancel()
+	observed := &treeCopyContext{Context: ctx, check: func() {
+		if len(sizes) == 1 {
+			cancel()
+		}
+	}}
+	require.ErrorIs(t, copyTreeLink(observed, root, "copy", map[string]string{"copy": "source"}, nil, sizes), context.Canceled)
+	assert.Len(t, sizes, 1)
+}
+
+type treeCopyContext struct {
+	context.Context
+	check func()
+}
+
+func (ctx *treeCopyContext) Err() error {
+	ctx.check()
+	return ctx.Context.Err()
+}

act/common/git/git.go

@@ -5,6 +5,7 @@
 package git
 
 import (
+	"bytes"
 	"context"
 	"crypto/sha256"
 	"encoding/base64"
@@ -27,6 +28,7 @@ import (
 	"gitea.com/gitea/runner/act/common"
 	"gitea.com/gitea/runner/act/common/logging"
 	"gitea.com/gitea/runner/internal/pkg/lock"
+	"gitea.com/gitea/runner/internal/pkg/process"
 )
 
 var (
@@ -387,6 +389,17 @@ func RemoteConfig(token string, insecureSkipTLS bool) []string {
 	return config
 }
 
+func ClientCertConfig(prefix, certFile, keyFile, executionOS string) []string {
+	if certFile == "" {
+		return nil
+	}
+	config := []string{prefix + "sslCert=" + certFile, prefix + "sslKey=" + keyFile}
+	if strings.EqualFold(executionOS, "windows") {
+		config = append(config, prefix+"sslBackend=openssl")
+	}
+	return config
+}
+
 // ConfigEnv applies `-c` style entries through the environment, keeping secrets out of argv.
 func ConfigEnv(config ...string) map[string]string {
 	env := map[string]string{"GIT_CONFIG_COUNT": strconv.Itoa(len(config))}
@@ -444,9 +457,7 @@ func runGitWithStdin(ctx context.Context, dir string, input *NewGitCloneExecutor
 	config := []string{"core.autocrlf=false", "core.eol=lf"} // keep action files LF
 	if input != nil {
 		config = append(config, RemoteConfig(input.Token, input.InsecureSkipTLS)...)
-		if input.ClientCertFile != "" {
-			config = append(config, "http.sslCert="+input.ClientCertFile, "http.sslKey="+input.ClientKeyFile)
-		}
+		config = append(config, ClientCertConfig("http.", input.ClientCertFile, input.ClientKeyFile, runtime.GOOS)...)
 	}
 	if dir != "" {
 		args = append([]string{"-C", dir}, args...)
@@ -461,15 +472,28 @@ func runGitWithStdin(ctx context.Context, dir string, input *NewGitCloneExecutor
 		cmd.Env = append(cmd.Env, key+"="+value)
 	}
 	cmd.Env = append(cmd.Env, "GIT_TERMINAL_PROMPT=0")
-	if runtime.GOOS != "windows" {
+	var treeKill *process.TreeKill
+	if runtime.GOOS == "windows" {
+		treeKill = process.NewTreeKill(cmd) // a cancelled git leaves its remote helper holding the repository otherwise
+	} else {
 		cmd.Cancel = func() error { return cmd.Process.Signal(os.Interrupt) } // lets git remove its lock files
 	}
 	cmd.WaitDelay = time.Second
+	var stdout bytes.Buffer
 	var stderr strings.Builder
+	cmd.Stdout = &stdout
 	cmd.Stderr = &stderr
-	output, err := cmd.Output()
-	if err != nil {
-		return output, fmt.Errorf("git %s: %w: %s", strings.Join(args, " "), err, strings.TrimSpace(stderr.String()))
+	err := cmd.Start()
+	if err == nil {
+		if treeKill != nil {
+			if killer, captureErr := treeKill.Capture(cmd.Process); captureErr == nil {
+				defer killer.Close()
+			}
+		}
+		err = cmd.Wait()
 	}
-	return output, nil
+	if err != nil {
+		return stdout.Bytes(), fmt.Errorf("git %s: %w: %s", strings.Join(args, " "), err, strings.TrimSpace(stderr.String()))
+	}
+	return stdout.Bytes(), nil
 }

act/common/git/git_test.go

@@ -54,6 +54,22 @@ func TestMain(m *testing.M) {
 	os.Exit(code)
 }
 
+func TestClientCertConfig(t *testing.T) {
+	for _, testcase := range []struct {
+		prefix, certFile, executionOS string
+		expected                      []string
+	}{
+		{"http.", "cert.pem", "windows", []string{"http.sslCert=cert.pem", "http.sslKey=key.pem", "http.sslBackend=openssl"}},
+		{"http.https://example.com/.", "cert.pem", "Windows", []string{"http.https://example.com/.sslCert=cert.pem", "http.https://example.com/.sslKey=key.pem", "http.https://example.com/.sslBackend=openssl"}},
+		{"http.", "cert.pem", "Linux", []string{"http.sslCert=cert.pem", "http.sslKey=key.pem"}},
+		{"http.", "", "Windows", nil},
+	} {
+		t.Run(testcase.prefix+testcase.certFile+testcase.executionOS, func(t *testing.T) {
+			assert.Equal(t, testcase.expected, ClientCertConfig(testcase.prefix, testcase.certFile, "key.pem", testcase.executionOS))
+		})
+	}
+}
+
 func TestFindGitSlug(t *testing.T) {
 	for _, testcase := range []struct {
 		remoteURL string
@@ -185,7 +201,8 @@ func TestGitFindRef(t *testing.T) {
 func TestGitCloneExecutor(t *testing.T) {
 	remoteDir, workDir := newGitRemote(t)
 	require.NoError(t, os.WriteFile(filepath.Join(workDir, "action.sh"), []byte("#!/bin/sh\necho hi\n"), 0o755))
-	require.NoError(t, gitCmd("-C", workDir, "add", "action.sh"))
+	require.NoError(t, os.WriteFile(filepath.Join(workDir, ".gitattributes"), []byte("*.sh text\n"), 0o644))
+	require.NoError(t, gitCmd("-C", workDir, "add", "action.sh", ".gitattributes"))
 	require.NoError(t, gitCmd("-C", workDir, "commit", "-m", "initial"))
 	require.NoError(t, gitCmd("-C", workDir, "tag", "v2"))
 	require.NoError(t, gitCmd("-C", workDir, "push", "-u", "origin", "main"))
@@ -200,7 +217,7 @@ func TestGitCloneExecutor(t *testing.T) {
 	require.NoError(t, gitCmd("-C", workDir, "push", "origin", "main:refs/heads/"+fullSha[:4]))
 
 	hostConfig := filepath.Join(t.TempDir(), "gitconfig")
-	require.NoError(t, os.WriteFile(hostConfig, []byte("[core]\n\tautocrlf = true\n[url \""+remoteDir+"\"]\n\tinsteadOf = https://example.invalid/action\n"), 0o644))
+	require.NoError(t, os.WriteFile(hostConfig, []byte("[core]\n\tautocrlf = true\n\teol = crlf\n[url "+strconv.Quote(remoteDir)+"]\n\tinsteadOf = https://example.invalid/action\n"), 0o644))
 	t.Setenv("GIT_CONFIG_GLOBAL", hostConfig)
 	t.Setenv("GIT_DIR", t.TempDir())
 
@@ -676,8 +693,8 @@ func TestNewGitCloneExecutorFetchSendsTokenAndHonoursContext(t *testing.T) {
 
 	select {
 	case <-reached:
-	case <-time.After(10 * time.Second):
-		t.Fatal("the executor never reached the remote")
+	case err := <-done:
+		t.Fatalf("the executor finished before reaching the remote: %v", err)
 	}
 	assert.Equal(t, "Basic "+base64.StdEncoding.EncodeToString([]byte("token:secret")), authorization)
 	cancel()

act/common/lookup_fold.go

@@ -0,0 +1,20 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package common
+
+import "strings"
+
+// LookupFold finds name in values, ignoring case where the environment does, as GitHub's inputs always do.
+func LookupFold[V any](values map[string]V, name string, caseInsensitive bool) (V, bool) {
+	if value, ok := values[name]; ok || !caseInsensitive {
+		return value, ok
+	}
+	for key, value := range values {
+		if strings.EqualFold(key, name) {
+			return value, true
+		}
+	}
+	var zero V
+	return zero, false
+}

act/container/container_types.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"io"
 	"path"
+	"runtime"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -20,6 +21,8 @@ import (
 	"github.com/moby/moby/api/types/container"
 )
 
+var hostOS = runtime.GOOS // replaced in tests
+
 // ExitCodeError reports a non-zero process exit code from a container command.
 type ExitCodeError int
 

act/container/docker_build.go

@@ -125,6 +125,10 @@ func createBuildContext(ctx context.Context, contextDir, relDockerfile string) (
 }
 
 func writeBuildContext(ctx context.Context, w io.Writer, contextDir string, includes []string, pm *patternmatcher.PatternMatcher) error {
+	contextDir, err := filepath.EvalSymlinks(contextDir)
+	if err != nil {
+		return err
+	}
 	tw := tar.NewWriter(w)
 	seen := map[string]bool{}
 	hardlinks := map[uint64]string{}
@@ -132,8 +136,7 @@ func writeBuildContext(ctx context.Context, w io.Writer, contextDir string, incl
 	for _, include := range includes {
 		include = filepath.FromSlash(include)
 		var parents []parentMatch
-		root := strings.TrimSuffix(contextDir, string(filepath.Separator)) + string(filepath.Separator) + include // unlike filepath.Join, follows a symlinked context dir as docker build does
-		err := filepath.WalkDir(root, func(file string, entry fs.DirEntry, err error) error {
+		err := filepath.WalkDir(filepath.Join(contextDir, include), func(file string, entry fs.DirEntry, err error) error {
 			if err != nil {
 				return leaveOut(ctx, file, err)
 			}
@@ -210,7 +213,7 @@ func addBuildContextEntry(ctx context.Context, tw *tar.Writer, file, rel string,
 			return leaveOut(ctx, file, err)
 		}
 	}
-	header, err := tar.FileInfoHeader(noNameLookups{info}, link)
+	header, err := tar.FileInfoHeader(noNameLookups{info}, filepath.ToSlash(link))
 	if err != nil {
 		return err
 	}

act/container/docker_build_test.go

@@ -50,7 +50,7 @@ func TestCreateBuildContextFollowsDockerignoreAndSymlinkedRootButKeepsDockerfile
 
 	contexts := []string{dir}
 	if link := filepath.Join(t.TempDir(), "link"); os.Symlink(dir, link) == nil {
-		contexts = append(contexts, link+string(filepath.Separator))
+		contexts = append(contexts, link, link+string(filepath.Separator))
 	}
 
 	for _, contextDir := range contexts {

act/container/docker_cli.go

@@ -351,7 +351,7 @@ type containerConfig struct {
 // parse parses the args for the specified command and generates a Config,
 // a HostConfig and returns them with the specified command.
 // If the specified args are not valid, it will return an error.
-func parse(flags *pflag.FlagSet, copts *containerOptions, serverOS string) (*containerConfig, error) { //nolint:gocyclo,unparam // verbatim copy from docker/cli
+func parse(flags *pflag.FlagSet, copts *containerOptions, serverOS string) (*containerConfig, error) { //nolint:gocyclo // verbatim copy from docker/cli
 	var (
 		attachStdin  = copts.attach.Get("stdin")
 		attachStdout = copts.attach.Get("stdout")
@@ -724,6 +724,10 @@ func parse(flags *pflag.FlagSet, copts *containerOptions, serverOS string) (*con
 	}, nil
 }
 
+func isUserDefinedNetwork(mode container.NetworkMode) bool { // Docker's helper uses the host OS instead of the daemon's.
+	return !mode.IsDefault() && mode != network.NetworkBridge && mode != network.NetworkHost && !mode.IsNone() && !mode.IsContainer()
+}
+
 // parseNetworkOpts converts --network advanced options to endpoint-specs, and combines
 // them with the old --network-alias and --links. If returns an error if conflicting options
 // are found.
@@ -752,7 +756,7 @@ func parseNetworkOpts(copts *containerOptions) (map[string]*network.EndpointSett
 	}
 
 	for i, n := range copts.netMode.Value() {
-		if container.NetworkMode(n.Target).IsUserDefined() {
+		if isUserDefinedNetwork(container.NetworkMode(n.Target)) {
 			hasUserDefined = true
 		} else {
 			hasNonUserDefined = true
@@ -814,7 +818,7 @@ func applyContainerOptions(n *opts.NetworkAttachmentOpts, copts *containerOption
 	}
 	// For a user-defined network, "--link" is an endpoint option, it creates an alias. But,
 	// for the default bridge it defines a legacy-link.
-	if container.NetworkMode(n.Target).IsUserDefined() && copts.links.Len() > 0 {
+	if isUserDefinedNetwork(container.NetworkMode(n.Target)) && copts.links.Len() > 0 {
 		n.Links = slices.Clone(copts.links.GetSlice())
 	}
 	if copts.ipv4Address != nil {
@@ -840,7 +844,7 @@ func parseNetworkAttachmentOpt(ep opts.NetworkAttachmentOpts) (*network.Endpoint
 	if strings.TrimSpace(ep.Target) == "" {
 		return nil, errors.New("no name set for network")
 	}
-	if !container.NetworkMode(ep.Target).IsUserDefined() {
+	if !isUserDefinedNetwork(container.NetworkMode(ep.Target)) {
 		if len(ep.Aliases) > 0 {
 			return nil, errors.New("network-scoped aliases are only supported for user-defined networks")
 		}

act/container/docker_proxy_test.go

@@ -484,6 +484,10 @@ type probeClient struct {
 	containers []container.Summary
 }
 
+func (c *probeClient) Info(_ctx context.Context, _opts mobyclient.InfoOptions) (mobyclient.SystemInfoResult, error) {
+	return mobyclient.SystemInfoResult{}, nil
+}
+
 func (c *probeClient) Close() error {
 	return nil
 }
@@ -766,6 +770,9 @@ func TestDaemonSeesDir(t *testing.T) {
 }
 
 func TestRunnerContainerWorkdir(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("a runner container is Linux")
+	}
 	workdir := t.TempDir()
 	t.Chdir(workdir)
 	volume := container.MountPoint{Type: mount.TypeVolume, Source: "/daemon/_data", Destination: filepath.Dir(workdir)}

act/container/docker_run.go

@@ -366,6 +366,7 @@ type containerReference struct {
 	id         string
 	input      *NewContainerInput
 	pullPolicy string
+	daemonOS   string
 	UID        int
 	GID        int
 	// attachDone is closed by the attach() streaming goroutine once it has
@@ -375,13 +376,18 @@ type containerReference struct {
 	LinuxContainerEnvironmentExtensions
 }
 
-func GetDockerClient(ctx context.Context) (cli client.APIClient, err error) {
+func GetDockerClient(ctx context.Context) (client.APIClient, error) {
+	cli, _, err := newDockerClient(ctx)
+	return cli, err
+}
+
+func newDockerClient(ctx context.Context) (cli client.APIClient, daemonOS string, err error) {
 	dockerHost := os.Getenv("DOCKER_HOST")
 
 	if strings.HasPrefix(dockerHost, "ssh://") {
 		var args []string
 		if args, err = sshArgs(dockerHost); err != nil {
-			return nil, err
+			return nil, "", err
 		}
 		cli, err = client.New(
 			client.WithHost("http://docker.example.com"), // the dialer below ignores the address
@@ -391,16 +397,17 @@ func GetDockerClient(ctx context.Context) (cli client.APIClient, err error) {
 		cli, err = client.New(client.FromEnv)
 	}
 	if err != nil {
-		return nil, fmt.Errorf("failed to connect to docker daemon: %w", err)
+		return nil, "", fmt.Errorf("failed to connect to docker daemon: %w", err)
 	}
 	// Best-effort API version negotiation, matching the old client.NegotiateAPIVersion
 	// behaviour. Ping failures here are non-fatal: the connection is exercised again on
 	// the first real call, and the client falls back to the daemon's default API version.
-	if _, err := cli.Ping(ctx, client.PingOptions{NegotiateAPIVersion: true}); err != nil {
+	ping, err := cli.Ping(ctx, client.PingOptions{NegotiateAPIVersion: true})
+	if err != nil {
 		common.Logger(ctx).Warnf("docker daemon ping during version negotiation failed, continuing: %v", err)
 	}
 
-	return cli, nil
+	return cli, ping.OSType, nil
 }
 
 func GetHostInfo(ctx context.Context) (system.Info, error) {
@@ -440,16 +447,32 @@ func RunnerArch(ctx context.Context) string {
 	return info.Architecture
 }
 
+func (cr *containerReference) targetOS(ctx context.Context) string {
+	if cr.daemonOS == "" {
+		cr.daemonOS = "linux"
+		if cr.cli != nil {
+			if result, err := cr.cli.Info(ctx, client.InfoOptions{}); err == nil && result.Info.OSType != "" {
+				cr.daemonOS = result.Info.OSType
+			}
+		}
+	}
+	return cr.daemonOS
+}
+
+func (cr *containerReference) markExecutable(ctx context.Context) bool {
+	return hostOS == "windows" && cr.targetOS(ctx) == "linux"
+}
+
 func (cr *containerReference) connect() common.Executor {
 	return func(ctx context.Context) error {
 		if cr.cli != nil {
 			return nil
 		}
-		cli, err := GetDockerClient(ctx)
+		cli, daemonOS, err := newDockerClient(ctx)
 		if err != nil {
 			return err
 		}
-		cr.cli = cli
+		cr.cli, cr.daemonOS = cli, daemonOS
 		return nil
 	}
 }
@@ -459,6 +482,7 @@ func (cr *containerReference) Close() common.Executor {
 		if cr.cli != nil {
 			err := cr.cli.Close()
 			cr.cli = nil
+			cr.daemonOS = ""
 			if err != nil {
 				return fmt.Errorf("failed to close client: %w", err)
 			}
@@ -603,7 +627,8 @@ func (cr *containerReference) mergeContainerConfigs(ctx context.Context, config
 		copts.privileged = false
 	}
 
-	containerConfig, err := parse(flags, copts, runtime.GOOS)
+	serverOS := cr.targetOS(ctx)
+	containerConfig, err := parse(flags, copts, serverOS)
 	if err != nil {
 		return fmt.Errorf("cannot process container options: '%s': '%w'", options, err)
 	}
@@ -618,7 +643,7 @@ func (cr *containerReference) mergeContainerConfigs(ctx context.Context, config
 
 	// For Gitea, forcing --privileged off is not enough, other options reach the host too
 	if !hostConfig.Privileged {
-		trusted, err := parseOptionsHostConfig(cr.input.RunnerOptions)
+		trusted, err := parseOptionsHostConfig(cr.input.RunnerOptions, serverOS)
 		if err != nil {
 			return err
 		}
@@ -731,9 +756,7 @@ func (cr *containerReference) create(capAdd, capDrop []string) common.Executor {
 		cr.sanitizeConfig(ctx, hostConfig)
 
 		var networkingConfig *network.NetworkingConfig
-		n := hostConfig.NetworkMode
-		// IsUserDefined and IsHost are broken on windows
-		if n.IsUserDefined() && n != "host" && len(input.NetworkAliases) > 0 {
+		if isUserDefinedNetwork(hostConfig.NetworkMode) && len(input.NetworkAliases) > 0 {
 			networkingConfig = &network.NetworkingConfig{
 				EndpointsConfig: map[string]*network.EndpointSettings{
 					input.NetworkMode: {Aliases: input.NetworkAliases},
@@ -919,7 +942,7 @@ func (cr *containerReference) copyDir(dstPath, srcPath string, useGitIgnore, ski
 		if actPath := cr.GetActPath(); strings.HasPrefix(dstPath+"/", actPath+"/") {
 			extractionRoot = actPath // keeps tar entries from crossing the image's /var/run symlink
 		}
-		if err := writeDirTar(ctx, tarFile, path.Join("/", strings.TrimPrefix(dstPath, extractionRoot)), srcPath, useGitIgnore, skipGitDir, cr.UID, cr.GID); err != nil {
+		if err := writeDirTar(ctx, tarFile, path.Join("/", strings.TrimPrefix(dstPath, extractionRoot)), srcPath, useGitIgnore, skipGitDir, cr.UID, cr.GID, cr.markExecutable(ctx)); err != nil {
 			return err
 		}
 
@@ -1090,12 +1113,12 @@ func resetOption[T any](logger *logging.Logger, option string, field *T, trusted
 
 // parseOptionsHostConfig parses one options string on its own, to see what it alone asks for.
 // Even "" goes through the parser, or its empty slices and maps would differ from a real parse.
-func parseOptionsHostConfig(options string) (*container.HostConfig, error) {
+func parseOptionsHostConfig(options, serverOS string) (*container.HostConfig, error) {
 	flags, copts, _, err := parseContainerOptions(options)
 	if err != nil {
 		return nil, err
 	}
-	containerConfig, err := parse(flags, copts, runtime.GOOS)
+	containerConfig, err := parse(flags, copts, serverOS)
 	if err != nil {
 		return nil, fmt.Errorf("cannot process container options: '%s': '%w'", options, err)
 	}

act/container/docker_run_test.go

@@ -27,10 +27,12 @@ import (
 	"gitea.com/gitea/runner/act/common/logging/logtest"
 
 	cerrdefs "github.com/containerd/errdefs"
+	"github.com/kballard/go-shellquote"
 	"github.com/moby/moby/api/pkg/stdcopy"
 	"github.com/moby/moby/api/types/container"
 	"github.com/moby/moby/api/types/mount"
 	"github.com/moby/moby/api/types/network"
+	"github.com/moby/moby/api/types/system"
 	mobyclient "github.com/moby/moby/client"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
@@ -65,6 +67,14 @@ func TestDockerEnvironmentUsesContainerPath(t *testing.T) {
 type mockDockerClient struct {
 	mobyclient.APIClient
 	mock.Mock
+	info      system.Info
+	infoErr   error
+	infoCalls int
+}
+
+func (m *mockDockerClient) Info(_ctx context.Context, _opts mobyclient.InfoOptions) (mobyclient.SystemInfoResult, error) {
+	m.infoCalls++
+	return mobyclient.SystemInfoResult{Info: m.info}, m.infoErr
 }
 
 func (m *mockDockerClient) ServerVersion(ctx context.Context, opts mobyclient.ServerVersionOptions) (mobyclient.ServerVersionResult, error) {
@@ -689,11 +699,11 @@ func TestMergeContainerConfigsDropsVolumeDriversFromWorkflows(t *testing.T) {
 }
 
 func TestMergeContainerConfigsKeepsTheRunnersFilesAndEnvToItself(t *testing.T) {
-	hostFile := filepath.Join(t.TempDir(), "host.env")
+	hostFile := filepath.Join(t.TempDir(), "host file.env")
 	require.NoError(t, os.WriteFile(hostFile, []byte("STOLEN=from-the-host\n"), 0o600))
 	t.Setenv("RUNNER_SECRET", "s3cr3t")
 
-	for _, option := range []string{"--env-file " + hostFile, "--label-file " + hostFile} {
+	for _, option := range []string{shellquote.Join("--env-file", hostFile), shellquote.Join("--label-file", hostFile)} {
 		logger := logging.New(logtest.New())
 		cr := &containerReference{input: &NewContainerInput{NetworkMode: "bridge", WorkflowOptions: option}}
 
@@ -933,6 +943,7 @@ func TestContainerInfoFromInspect(t *testing.T) {
 			"/etc/hosts":                "",
 			"/etc/hostname":             "",
 		}, info.Mounts)
+		assert.Equal(t, "/var/lib/docker/volumes/job/_data/subdir", info.DaemonPath("/workspace/owner/repo/subdir"))
 	})
 }
 
@@ -998,6 +1009,39 @@ func TestDockerCreateKeepsInputEntrypoint(t *testing.T) {
 	}
 }
 
+func TestDockerCreateNetworkAliases(t *testing.T) {
+	for _, test := range []struct {
+		networkMode string
+		wantAliases bool
+	}{
+		{"job-network", true},
+		{"host", false},
+		{"bridge", false},
+		{"default", false},
+		{"none", false},
+		{"container:x", false},
+	} {
+		t.Run(test.networkMode, func(t *testing.T) {
+			cr := &containerReference{
+				input: &NewContainerInput{NetworkMode: test.networkMode, NetworkAliases: []string{"service"}},
+				cli: &probeClient{create: func(_ctx context.Context, opts mobyclient.ContainerCreateOptions) (mobyclient.ContainerCreateResult, error) {
+					assert.Equal(t, container.NetworkMode(test.networkMode), opts.HostConfig.NetworkMode)
+					if test.wantAliases {
+						assert.Equal(t, &network.NetworkingConfig{EndpointsConfig: map[string]*network.EndpointSettings{
+							"job-network": {Aliases: []string{"service"}},
+						}}, opts.NetworkingConfig)
+					} else {
+						assert.Nil(t, opts.NetworkingConfig)
+					}
+					return mobyclient.ContainerCreateResult{ID: "created"}, nil
+				}},
+			}
+			require.NoError(t, cr.create(nil, nil)(t.Context()))
+			assert.Equal(t, "created", cr.id)
+		})
+	}
+}
+
 func TestMergeContainerConfigsKeepsNetworkAliasesFromOptions(t *testing.T) {
 	logger := logging.New(logtest.New())
 	cr := &containerReference{input: &NewContainerInput{
@@ -1019,3 +1063,92 @@ func TestSupportsContainerImagePlatformDaemonError(t *testing.T) {
 	require.ErrorContains(t, err, "cannot connect to the Docker daemon")
 	assert.False(t, supported)
 }
+
+func TestContainerOptionsUseDaemonOS(t *testing.T) {
+	for _, testcase := range []struct {
+		name     string
+		serverOS string
+		infoErr  error
+		device   string
+		expected container.DeviceMapping
+	}{
+		{name: "Linux daemon", serverOS: "linux", device: "/dev/kvm:/dev/kvm:rwm", expected: container.DeviceMapping{PathOnHost: "/dev/kvm", PathInContainer: "/dev/kvm", CgroupPermissions: "rwm"}},
+		{name: "unknown daemon", device: "/dev/kvm:/dev/kvm:rwm", expected: container.DeviceMapping{PathOnHost: "/dev/kvm", PathInContainer: "/dev/kvm", CgroupPermissions: "rwm"}},
+		{name: "unavailable daemon info", infoErr: errors.New("unavailable"), device: "/dev/kvm:/dev/kvm:rwm", expected: container.DeviceMapping{PathOnHost: "/dev/kvm", PathInContainer: "/dev/kvm", CgroupPermissions: "rwm"}},
+		{name: "Windows daemon", serverOS: "windows", device: "class/01234567-89ab-cdef-0123-456789abcdef", expected: container.DeviceMapping{PathOnHost: "class/01234567-89ab-cdef-0123-456789abcdef"}},
+	} {
+		t.Run(testcase.name, func(t *testing.T) {
+			cli := &mockDockerClient{info: system.Info{OSType: testcase.serverOS}, infoErr: testcase.infoErr}
+			cr := &containerReference{cli: cli, input: &NewContainerInput{RunnerOptions: "--device=" + testcase.device, WorkflowOptions: "--device=" + testcase.device, NetworkMode: "bridge"}}
+			for range 2 {
+				hostConfig := &container.HostConfig{}
+				require.NoError(t, cr.mergeContainerConfigs(t.Context(), &container.Config{}, hostConfig))
+				assert.Equal(t, []container.DeviceMapping{testcase.expected}, hostConfig.Devices)
+			}
+			assert.Equal(t, 1, cli.infoCalls)
+		})
+	}
+}
+
+func TestConnectTakesDaemonOSFromPing(t *testing.T) {
+	var infos atomic.Int32
+	daemon := httptest.NewServer(http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
+		writer.Header().Set("API-Version", "1.47")
+		writer.Header().Set("OSType", "windows")
+		if strings.HasSuffix(request.URL.Path, "/info") {
+			infos.Add(1)
+		}
+	}))
+	t.Cleanup(daemon.Close)
+	t.Setenv("DOCKER_HOST", daemon.URL)
+	cr := &containerReference{input: &NewContainerInput{}}
+	require.NoError(t, cr.connect()(t.Context()))
+	assert.Equal(t, "windows", cr.targetOS(t.Context()))
+	assert.Zero(t, infos.Load())
+}
+
+func TestContainerCopyModes(t *testing.T) {
+	for _, testcase := range []struct {
+		hostOS, serverOS string
+		expected         int64
+	}{
+		{"windows", "linux", 0o755},
+		{"windows", "windows", 0o666},
+		{"linux", "linux", 0o666},
+	} {
+		t.Run(testcase.hostOS+"-"+testcase.serverOS, func(t *testing.T) {
+			source := t.TempDir()
+			require.NoError(t, os.WriteFile(filepath.Join(source, "run.sh"), []byte("#!/bin/sh\n"), 0o666))
+			require.NoError(t, os.Chmod(filepath.Join(source, "run.sh"), 0o666))
+			file := &FileEntry{Name: "run.sh", Mode: 0o600, Body: "#!/bin/sh\n"}
+			original := hostOS
+			hostOS = testcase.hostOS
+			t.Cleanup(func() { hostOS = original })
+			cli := &mockDockerClient{info: system.Info{OSType: testcase.serverOS}}
+			var modes []int64
+			cli.On("CopyToContainer", mock.Anything, "job", mock.Anything).
+				Run(func(args mock.Arguments) {
+					reader := tar.NewReader(args.Get(2).(mobyclient.CopyToContainerOptions).Content)
+					header, err := reader.Next()
+					require.NoError(t, err)
+					modes = append(modes, header.Mode)
+					assert.Equal(t, "run.sh", filepath.Base(header.Name))
+					content, err := io.ReadAll(reader)
+					require.NoError(t, err)
+					assert.Equal(t, file.Body, string(content))
+					_, err = reader.Next()
+					require.ErrorIs(t, err, io.EOF)
+				}).Return(mobyclient.CopyToContainerResult{}, nil).Twice()
+			cr := &containerReference{cli: cli, id: "job", input: &NewContainerInput{}}
+			require.NoError(t, cr.copyContent("/workspace", file)(t.Context()))
+			require.NoError(t, cr.copyDir("/workspace", source+string(filepath.Separator), false, true)(t.Context()))
+			assert.Equal(t, []int64{0o600, testcase.expected}, modes)
+			if testcase.hostOS == "windows" {
+				assert.Equal(t, 1, cli.infoCalls)
+			} else {
+				assert.Zero(t, cli.infoCalls)
+			}
+			cli.AssertExpectations(t)
+		})
+	}
+}

act/container/executions_environment.go

@@ -4,7 +4,18 @@
 
 package container
 
-import "context"
+import (
+	"context"
+	"path"
+	"strings"
+)
+
+func JoinPath(elem ...string) string { // path.Join would collapse the leading // of a UNC act path on a Windows host
+	if len(elem) > 0 && strings.HasPrefix(elem[0], "//") {
+		return "/" + path.Join(elem...)
+	}
+	return path.Join(elem...)
+}
 
 type ExecutionsEnvironment interface {
 	Container

act/container/host_environment.go

@@ -40,7 +40,8 @@ type HostEnvironment struct {
 	// when Workdir points at a caller-owned checkout (e.g. `act` local mode).
 	CleanWorkdir bool
 	ActPath      string
-	CleanUp      func()
+	Root         string
+	TrackingID   string // RUNNER_TRACKING_ID of the job, a step with another value keeps its leftovers
 	StdOut       io.Writer
 	AllocatePTY  bool // allocate a pseudo-TTY for each step's process
 
@@ -261,6 +262,7 @@ func (e *HostEnvironment) exec(ctx context.Context, command []string, cmdline st
 	// Flush any buffered, not-yet-newline-terminated trailing line, as the docker backend
 	// does in waitForCommand, so the final line of a command's output is not lost.
 	defer common.FlushWriter(e.StdOut)
+	process.UTF8Console()
 
 	f, err := lookupPathHost(command[0], env, e.StdOut)
 	if err != nil {
@@ -270,7 +272,12 @@ func (e *HostEnvironment) exec(ctx context.Context, command []string, cmdline st
 	cmd.Path = f
 	cmd.Args = command
 	cmd.Stdout = e.StdOut
-	cmd.Env = getEnvListFromMap(env)
+	trackingID := e.TrackingID
+	if value, ok := common.LookupFold(env, "RUNNER_TRACKING_ID", e.IsEnvironmentCaseInsensitive()); ok {
+		trackingID = value
+	}
+	tracked := trackingID == e.TrackingID
+	cmd.Env = append(getEnvListFromMap(env), "RUNNER_TRACKING_ID="+trackingID)
 	cmd.Stderr = e.StdOut
 	cmd.Dir = wd
 	cmd.SysProcAttr = process.SysProcAttr(cmdline, false)
@@ -278,6 +285,7 @@ func (e *HostEnvironment) exec(ctx context.Context, command []string, cmdline st
 	// Kills the step's whole tree on cancellation and bounds the post-exit I/O
 	// wait, so an orphan holding cmd's stdout pipe cannot hang cmd.Wait().
 	treeKill := process.NewTreeKill(cmd)
+	treeKill.KeepLeftovers = !tracked
 
 	var ppty *os.File
 	var tty *os.File
@@ -311,10 +319,10 @@ func (e *HostEnvironment) exec(ctx context.Context, command []string, cmdline st
 	if err := cmd.Start(); err != nil {
 		return err
 	}
-	// Assign before the step's Killer so the step's job nests inside the group's;
-	// cancellation still scopes to this step's tree.
-	if err := e.processGroup(ctx).Assign(cmd.Process); err != nil {
-		common.Logger(ctx).Warnf("could not assign the step's process to the job's process group; a process it leaves behind may outlive the job: %v", err)
+	if tracked {
+		if err := e.processGroup(ctx).Assign(cmd.Process); err != nil {
+			common.Logger(ctx).Warnf("could not assign the step's process to the job's process group, a process it leaves behind may outlive the job: %v", err)
+		}
 	}
 	if k, kerr := treeKill.Capture(cmd.Process); kerr != nil {
 		common.Logger(ctx).Warnf("process tree kill setup failed, falling back to single-process kill: %v", kerr)
@@ -365,9 +373,7 @@ func (e *HostEnvironment) UpdateFromEnv(srcPath string, env *map[string]string)
 // removeAll is a var so tests can substitute a blocking stub.
 var removeAll = os.RemoveAll
 
-// removeAllWithContext returns once the delete finishes or ctx is cancelled. On
-// cancellation the goroutine leaks: a delete inside a syscall cannot be
-// interrupted (see runWithTimeout).
+// Returns on cancel while an uninterruptible delete keeps running, freeing the runner's capacity slot.
 func removeAllWithContext(ctx context.Context, path string) error {
 	done := make(chan error, 1)
 	go func() { done <- removeAll(path) }()
@@ -409,35 +415,6 @@ func removePathWithRetry(ctx context.Context, path string) error {
 	return lastErr
 }
 
-// buildWindowsWorkspaceKillScript builds a PowerShell command that taskkills
-// every process tree whose ExecutablePath or CommandLine references one of the
-// given workspace dirs, releasing file handles for cleanup. Win32_Process
-// exposes both fields (Get-Process doesn't, wmic is deprecated); matching is on
-// the dir+separator prefix via ordinal String methods, so a name-prefix sibling
-// (job1 vs job10) is spared and path metacharacters stay literal.
-func buildWindowsWorkspaceKillScript(dirs []string) string {
-	quoted := make([]string, len(dirs))
-	for i, d := range dirs {
-		// Single-quoted PowerShell literal; escape ' by doubling it.
-		quoted[i] = "'" + strings.ReplaceAll(d, "'", "''") + "'"
-	}
-
-	return `$paths = @(` + strings.Join(quoted, ",") + `)
-$selfPid = $PID
-Get-CimInstance Win32_Process -ErrorAction SilentlyContinue | Where-Object {
-    if ($_.ProcessId -eq $selfPid) { return $false }
-    foreach ($p in $paths) {
-        $prefix = $p + '\'
-        if ($_.ExecutablePath -and $_.ExecutablePath.StartsWith($prefix, [System.StringComparison]::OrdinalIgnoreCase)) { return $true }
-        if ($_.CommandLine -and $_.CommandLine.IndexOf($prefix, [System.StringComparison]::OrdinalIgnoreCase) -ge 0) { return $true }
-    }
-    return $false
-} | ForEach-Object {
-    & taskkill.exe /PID $_.ProcessId /T /F 2>$null | Out-Null
-}
-`
-}
-
 func (e *HostEnvironment) terminateRunningProcesses(ctx context.Context) {
 	if runtime.GOOS != "windows" {
 		return
@@ -471,20 +448,10 @@ func (e *HostEnvironment) terminateRunningProcesses(ctx context.Context) {
 		return
 	}
 
-	script := buildWindowsWorkspaceKillScript(dirs)
-
-	cmd := exec.CommandContext(killCtx, "powershell.exe", "-NoProfile", "-NonInteractive", "-Command", script)
-	out, err := cmd.CombinedOutput()
-	if err != nil {
-		logger.Debugf("workspace process-tree kill via PowerShell failed: %v output=%s", err, strings.TrimSpace(string(out)))
-	}
-
-	// Win32_Process exposes no working directory, so the scan above misses a
-	// process that merely runs in a workspace dir while pinning a handle on it.
-	if killed, err := process.KillProcessesWithCWDUnder(killCtx, dirs); err != nil {
-		logger.Debugf("workspace process kill by working directory reported errors: %v", err)
+	if killed, err := process.KillProcessesWithPaths(killCtx, dirs, e.TrackingID); err != nil {
+		logger.Debugf("workspace process cleanup reported errors: %v", err)
 	} else if killed > 0 {
-		logger.Debugf("terminated %d leftover process(es) by workspace working directory", killed)
+		logger.Debugf("terminated %d leftover workspace process(es)", killed)
 	}
 }
 
@@ -492,26 +459,6 @@ func (e *HostEnvironment) terminateRunningProcesses(ctx context.Context) {
 // wedge the runner slot. A var so tests can shrink it.
 var hostCleanupTimeout = 30 * time.Second
 
-// runWithTimeout returns context.DeadlineExceeded once timeout elapses, leaking
-// the goroutine: a delete blocked in a syscall (AV filter driver, dead network
-// mount) cannot be interrupted, and leaking scratch state beats losing the
-// runner's capacity slot forever. The idle stale-dir sweep reclaims it later.
-func runWithTimeout(fn func(), timeout time.Duration) error {
-	done := make(chan struct{})
-	go func() {
-		defer close(done)
-		fn()
-	}()
-	timer := time.NewTimer(timeout)
-	defer timer.Stop()
-	select {
-	case <-done:
-		return nil
-	case <-timer.C:
-		return context.DeadlineExceeded
-	}
-}
-
 func (e *HostEnvironment) Remove() common.Executor {
 	return func(ctx context.Context) error {
 		logger := common.Logger(ctx)
@@ -523,25 +470,14 @@ func (e *HostEnvironment) Remove() common.Executor {
 		}
 		e.terminateRunningProcesses(ctx)
 
-		// Removes per-job misc state only, never the toolcache root. Bounded because
-		// CleanUp is a caller-supplied, typically unbounded os.RemoveAll.
-		if e.CleanUp != nil {
-			logger.Debugf("running host environment cleanup callback")
-			if err := runWithTimeout(e.CleanUp, hostCleanupTimeout); err != nil {
-				logger.Warnf("host environment cleanup did not finish within %s; continuing job completion, scratch state may be leaked and is reclaimed by the idle stale-dir sweep", hostCleanupTimeout)
-			} else {
-				logger.Debugf("host environment cleanup callback finished")
-			}
-		}
-
 		// Detach: a cancelled ctx would skip removePathWithRetry's retries,
 		// which absorb Windows file-handle release lag after the kill above.
 		rmCtx, rmCancel := context.WithTimeout(context.Background(), hostCleanupTimeout)
 		defer rmCancel()
 
 		var errs []error
-		if err := removePathWithRetry(rmCtx, e.Path); err != nil {
-			logger.Warnf("failed to remove host misc state %s: %v", e.Path, err)
+		if err := removePathWithRetry(rmCtx, cmp.Or(e.Root, e.Path)); err != nil {
+			logger.Warnf("failed to remove host misc state %s: %v", cmp.Or(e.Root, e.Path), err)
 			errs = append(errs, err)
 		}
 		if e.CleanWorkdir {

act/container/host_environment_test.go

@@ -161,10 +161,12 @@ func TestHostEnvironmentRemoveWorkdir(t *testing.T) {
 				Path:         filepath.Join(miscRoot, "hostexecutor"),
 				Workdir:      workdir,
 				CleanWorkdir: owned,
-				CleanUp:      func() { _ = os.RemoveAll(miscRoot) },
+				Root:         miscRoot,
 			}
 			require.NoError(t, os.MkdirAll(e.Path, 0o700))
+			require.NoError(t, os.MkdirAll(filepath.Join(miscRoot, "tmp"), 0o700))
 			require.NoError(t, e.Remove()(t.Context()))
+			assert.NoDirExists(t, miscRoot)
 			_, err := os.Stat(workdir)
 			if owned {
 				assert.ErrorIs(t, err, os.ErrNotExist)
@@ -201,87 +203,38 @@ func TestRemoveAllWithContextDoesNotHangOnStuckDelete(t *testing.T) {
 }
 
 func TestHostEnvironmentRemoveDoesNotHang(t *testing.T) {
-	for _, phase := range []string{"CleanUp callback", "path removal"} {
-		t.Run(phase, func(t *testing.T) {
-			synctest.Test(t, func(t *testing.T) {
-				origTimeout := hostCleanupTimeout
-				hostCleanupTimeout = 100 * time.Millisecond
-				t.Cleanup(func() { hostCleanupTimeout = origTimeout })
-				release, stubDone := make(chan struct{}), make(chan struct{})
-				block := func() {
-					defer close(stubDone)
-					<-release
-				}
-				e := &HostEnvironment{Path: filepath.Join(t.TempDir(), "misc", "hostexecutor"), StdOut: os.Stdout}
-				if phase == "CleanUp callback" {
-					e.CleanUp = block
-				} else {
-					origRemoveAll := removeAll
-					removeAll = func(string) error {
-						block()
-						return nil
-					}
-					t.Cleanup(func() { removeAll = origRemoveAll })
-				}
-				t.Cleanup(func() {
-					close(release)
-					<-stubDone
-				})
-				require.NoError(t, os.MkdirAll(e.Path, 0o700))
-				done := make(chan error, 1)
-				go func() { done <- e.Remove()(common.WithLogger(t.Context(), logging.Default())) }()
-				select {
-				case err := <-done:
-					require.NoError(t, err)
-				case <-time.After(10 * time.Second):
-					t.Fatalf("Remove() hung on a stuck %s", phase)
-				}
-			})
+	synctest.Test(t, func(t *testing.T) {
+		origTimeout, origRemoveAll := hostCleanupTimeout, removeAll
+		hostCleanupTimeout = 100 * time.Millisecond
+		release, stubDone := make(chan struct{}), make(chan struct{})
+		removeAll = func(string) error {
+			defer close(stubDone)
+			<-release
+			return nil
+		}
+		t.Cleanup(func() {
+			close(release)
+			<-stubDone
+			hostCleanupTimeout, removeAll = origTimeout, origRemoveAll
 		})
+		e := &HostEnvironment{Path: filepath.Join(t.TempDir(), "misc", "hostexecutor"), StdOut: os.Stdout}
+		require.NoError(t, os.MkdirAll(e.Path, 0o700))
+		done := make(chan error, 1)
+		go func() { done <- e.Remove()(common.WithLogger(t.Context(), logging.Default())) }()
+		select {
+		case err := <-done:
+			require.NoError(t, err)
+		case <-time.After(10 * time.Second):
+			t.Fatal("Remove() hung on a stuck path removal")
+		}
+	})
+}
+
+func TestJoinPath(t *testing.T) {
+	assert.Equal(t, "//server/share/act/workflow/envs.txt", JoinPath("//server/share/act", "workflow/envs.txt"))
+	assert.Equal(t, "/var/run/act/workflow/envs.txt", JoinPath("/var/run/act/", "workflow", "envs.txt"))
+	for _, root := range []string{"//server/share/act", "/var/run/act", "C:/act"} {
+		assert.Equal(t, root+"/actions/key/main.go.out", JoinPath(root+"/actions/key", "main.go.out"))
+		assert.Equal(t, root+"/workflow", JoinPath(root+"/workflow/outputcmd.txt", ".."))
 	}
 }
-
-func TestBuildWindowsWorkspaceKillScript(t *testing.T) {
-	t.Run("single dir", func(t *testing.T) {
-		s := buildWindowsWorkspaceKillScript([]string{`C:\workspace\job1`})
-		assert.Contains(t, s, `$paths = @('C:\workspace\job1')`)
-		assert.Contains(t, s, "$selfPid = $PID")
-		assert.Contains(t, s, "$_.ProcessId -eq $selfPid")
-		assert.Contains(t, s, `$prefix = $p + '\'`)
-		assert.Contains(t, s, "$_.ExecutablePath.StartsWith($prefix")
-		assert.Contains(t, s, "$_.CommandLine.IndexOf($prefix")
-		assert.Contains(t, s, "taskkill.exe /PID $_.ProcessId /T /F")
-	})
-
-	t.Run("multiple dirs comma-separated", func(t *testing.T) {
-		s := buildWindowsWorkspaceKillScript([]string{
-			`C:\work\path`,
-			`C:\work\workdir`,
-			`C:\Users\runner\AppData\Local\Temp\job-42`,
-		})
-		assert.Contains(t, s, `'C:\work\path'`)
-		assert.Contains(t, s, `'C:\work\workdir'`)
-		assert.Contains(t, s, `'C:\Users\runner\AppData\Local\Temp\job-42'`)
-		assert.Contains(t, s, `'C:\work\path','C:\work\workdir',`)
-	})
-
-	t.Run("path with single quote is escaped", func(t *testing.T) {
-		s := buildWindowsWorkspaceKillScript([]string{`C:\work\it's\path`})
-		assert.Contains(t, s, `'C:\work\it''s\path'`)
-		assert.NotContains(t, s, `'C:\work\it's\path'`)
-	})
-
-	t.Run("path with wildcard metacharacters is matched literally", func(t *testing.T) {
-		s := buildWindowsWorkspaceKillScript([]string{`C:\work\[job]?1`})
-		assert.Contains(t, s, `'C:\work\[job]?1'`)
-		assert.NotContains(t, s, "-like")
-		assert.Contains(t, s, "StartsWith")
-		assert.Contains(t, s, "IndexOf")
-	})
-
-	t.Run("empty dir list still produces a valid script", func(t *testing.T) {
-		s := buildWindowsWorkspaceKillScript(nil)
-		assert.Contains(t, s, "$paths = @()")
-		assert.Contains(t, s, "Get-CimInstance Win32_Process")
-	})
-}

act/container/host_environment_windows_test.go

@@ -0,0 +1,138 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package container
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+	"unsafe"
+
+	"github.com/stretchr/testify/require"
+	"golang.org/x/sys/windows"
+)
+
+func TestHostEnvironmentTrackingCleanup(t *testing.T) {
+	for _, tracking := range []string{"default", "", "shared-helper"} {
+		t.Run("tracking="+tracking, func(t *testing.T) {
+			ctx, cancel := context.WithTimeout(t.Context(), 30*time.Second)
+			defer cancel()
+			listener, err := net.Listen("tcp4", "127.0.0.1:0")
+			require.NoError(t, err)
+			defer listener.Close()
+			stop := context.AfterFunc(ctx, func() { _ = listener.Close() })
+			defer stop()
+			workspace := t.TempDir()
+			environment := &HostEnvironment{Path: t.TempDir(), TmpDir: workspace, Workdir: workspace, TrackingID: "gitea_test", StdOut: io.Discard}
+			env := map[string]string{}
+			for _, entry := range os.Environ() {
+				if name, value, ok := strings.Cut(entry, "="); ok && !strings.EqualFold(name, "RUNNER_TRACKING_ID") {
+					env[name] = value
+				}
+			}
+			env["GITEA_TRACKING_HELPER"] = "step"
+			env["GITEA_TRACKING_WORKSPACE"] = workspace
+			env["GITEA_TRACKING_ADDRESS"] = listener.Addr().String()
+			if tracking == "default" {
+				env["RUNNER_TRACKING_ID"] = environment.TrackingID
+				env["runner_tracking_id"] = "shared-helper"
+			} else {
+				env["runner_tracking_id"] = tracking
+			}
+			result := make(chan error, 1)
+			go func() {
+				result <- environment.Exec([]string{os.Args[0], "-test.run=^TestHostTrackingHelper$"}, env, "", workspace)(ctx)
+			}()
+			step, err := listener.Accept()
+			require.NoError(t, err)
+			defer step.Close()
+			require.NoError(t, step.SetDeadline(time.Now().Add(20*time.Second)))
+			var stepPID int
+			_, err = fmt.Fscanln(step, &stepPID)
+			require.NoError(t, err)
+			stepHandle, err := windows.OpenProcess(windows.PROCESS_QUERY_LIMITED_INFORMATION, false, uint32(stepPID))
+			require.NoError(t, err)
+			defer func() { _ = windows.CloseHandle(stepHandle) }()
+			require.Eventually(t, func() bool {
+				var assigned int32
+				result, _, _ := windows.NewLazySystemDLL("kernel32.dll").NewProc("IsProcessInJob").Call(uintptr(stepHandle), 0, uintptr(unsafe.Pointer(&assigned)))
+				return result != 0 && assigned != 0
+			}, 5*time.Second, 10*time.Millisecond)
+			_, err = step.Write([]byte{1})
+			require.NoError(t, err)
+			var helpers []windows.Handle
+			for range 2 {
+				connection, err := listener.Accept()
+				require.NoError(t, err)
+				t.Cleanup(func() { _ = connection.Close() })
+				require.NoError(t, connection.SetReadDeadline(time.Now().Add(20*time.Second)))
+				var pid int
+				_, err = fmt.Fscanln(connection, &pid)
+				require.NoError(t, err)
+				handle, err := windows.OpenProcess(windows.SYNCHRONIZE|windows.PROCESS_TERMINATE, false, uint32(pid))
+				require.NoError(t, err)
+				t.Cleanup(func() {
+					_ = windows.TerminateProcess(handle, 1)
+					_, _ = windows.WaitForSingleObject(handle, 5000)
+					_ = windows.CloseHandle(handle)
+				})
+				helpers = append(helpers, handle)
+			}
+			select {
+			case err := <-result:
+				require.NoError(t, err)
+			case <-ctx.Done():
+				t.Fatal(ctx.Err())
+			}
+			require.NoError(t, environment.Remove()(ctx))
+			for _, handle := range helpers {
+				if tracking == "default" {
+					result, err := windows.WaitForSingleObject(handle, 5000)
+					require.NoError(t, err)
+					require.EqualValues(t, windows.WAIT_OBJECT_0, result)
+				} else {
+					result, err := windows.WaitForSingleObject(handle, 0)
+					require.NoError(t, err)
+					require.EqualValues(t, windows.WAIT_TIMEOUT, result)
+				}
+			}
+		})
+	}
+}
+
+func TestHostTrackingHelper(t *testing.T) {
+	mode := os.Getenv("GITEA_TRACKING_HELPER")
+	if mode == "" {
+		return
+	}
+	connection, err := net.Dial("tcp4", os.Getenv("GITEA_TRACKING_ADDRESS"))
+	require.NoError(t, err)
+	_, err = fmt.Fprintln(connection, os.Getpid())
+	require.NoError(t, err)
+	if mode == "step" {
+		_, err := bufio.NewReader(connection).ReadByte()
+		require.NoError(t, err)
+	}
+	if mode != "descendant" {
+		child := exec.Command(os.Args[0], "-test.run=^TestHostTrackingHelper$", filepath.Join(os.Getenv("GITEA_TRACKING_WORKSPACE"), "tracking-reference"))
+		child.Env = append(os.Environ(), "GITEA_TRACKING_HELPER="+map[string]string{"step": "helper", "helper": "descendant"}[mode])
+		require.NoError(t, child.Start())
+		if mode == "step" {
+			require.NoError(t, connection.Close())
+			os.Exit(0)
+		}
+	}
+	_, err = io.Copy(io.Discard, connection)
+	require.NoError(t, err)
+	require.NoError(t, connection.Close())
+	os.Exit(0)
+}

act/container/kubernetes.go

@@ -557,7 +557,7 @@ func (c *kubernetesContainer) Copy(destPath string, files ...*FileEntry) common.
 func (c *kubernetesContainer) CopyDir(destPath, srcPath string, useGitIgnore, skipGitDir bool) common.Executor {
 	return func(ctx context.Context) error {
 		return c.extract(ctx, destPath, true, func(writer io.Writer) error { // directories are actions and workspaces, megabytes of compressible sources
-			return writeDirTar(ctx, writer, "/", srcPath, useGitIgnore, skipGitDir, 0, 0)
+			return writeDirTar(ctx, writer, "/", srcPath, useGitIgnore, skipGitDir, 0, 0, hostOS == "windows")
 		})
 	}
 }

act/container/parse_env_file.go

@@ -21,7 +21,12 @@ import (
 
 // parseEnvFile reads a GITHUB_ENV style file, splitting lines like GitHub's runner on Windows or elsewhere.
 func parseEnvFile(e Container, srcPath string, env *map[string]string, windows bool) common.Executor {
-	localEnv := *env
+	return ParseEnvFile(e, srcPath, func(name, value string) {
+		(*env)[name] = value
+	}, windows)
+}
+
+func ParseEnvFile(e Container, srcPath string, setEnv func(name, value string), windows bool) common.Executor {
 	return func(ctx context.Context) error {
 		envTar, err := e.GetContainerArchive(ctx, srcPath)
 		if err != nil {
@@ -64,7 +69,7 @@ func parseEnvFile(e Container, srcPath string, env *map[string]string, windows b
 			multiLineEnv := strings.Index(line, "<<")
 			switch {
 			case singleLineEnv != -1 && (multiLineEnv == -1 || singleLineEnv < multiLineEnv):
-				localEnv[line[:singleLineEnv]] = line[singleLineEnv+1:]
+				setEnv(line[:singleLineEnv], line[singleLineEnv+1:])
 			case multiLineEnv != -1:
 				var multiLineEnvContent []string
 				multiLineEnvDelimiter := line[multiLineEnv+2:]
@@ -86,7 +91,7 @@ func parseEnvFile(e Container, srcPath string, env *map[string]string, windows b
 				if !delimiterFound {
 					return fmt.Errorf("invalid format delimiter '%v' not found before end of file", multiLineEnvDelimiter)
 				}
-				localEnv[line[:multiLineEnv]] = trimEnvLineEnding(strings.Join(multiLineEnvContent, ""), windows)
+				setEnv(line[:multiLineEnv], trimEnvLineEnding(strings.Join(multiLineEnvContent, ""), windows))
 			default:
 				return fmt.Errorf("invalid format '%v', expected a line with '=' or '<<'", line)
 			}

act/container/parse_env_file_test.go

@@ -34,6 +34,7 @@ func TestParseEnvFile(t *testing.T) {
 		want          map[string]string
 	}{
 		{"single line", "FOO=bar\nBAZ=qux\n", map[string]string{"FOO": "bar", "BAZ": "qux"}},
+		{"repeated names", "FOO=first\nfoo=middle\nFOO=last\n", map[string]string{"FOO": "last", "foo": "middle"}},
 		{"single line CRLF and final bare CR", "FOO=bar\r\nBAZ=qux\r", map[string]string{"FOO": "bar\r", "BAZ": "qux\r"}},
 		{"single line without final newline", "FOO=bar", map[string]string{"FOO": "bar"}},
 		{"blank lines", "\nFOO=bar\n\n   \nBAZ=qux\n\n", map[string]string{"FOO": "bar", "BAZ": "qux"}},
@@ -57,6 +58,17 @@ func TestParseEnvFile(t *testing.T) {
 			assert.Equal(t, test.want, env)
 		})
 	}
+	t.Run("ordered entries preserve repeated names", func(t *testing.T) {
+		hostEnv, envPath := newTestHostEnv(t)
+		require.NoError(t, os.WriteFile(envPath, []byte("FOO=first\r\nfoo<<EOF\r\nmiddle\r\nEOF\r\nFOO=last\r\n"), 0o600))
+		var entries [][2]string
+		require.NoError(t, ParseEnvFile(hostEnv, envPath, func(name, value string) {
+			entries = append(entries, [2]string{name, value})
+		}, true)(t.Context()))
+		assert.Equal(t, [][2]string{
+			{"FOO", "first"}, {"foo", "middle"}, {"FOO", "last"},
+		}, entries)
+	})
 	t.Run("Windows line endings", func(t *testing.T) {
 		hostEnv, envPath := newTestHostEnv(t)
 		require.NoError(t, os.WriteFile(envPath, []byte("FOO=bar\r\nMULTI<<EOF\r\nline1\r\nline2\nEOF\r\n"), 0o600))
@@ -86,13 +98,13 @@ func TestParseEnvFileInvalidHeredoc(t *testing.T) {
 	} {
 		t.Run(name, func(t *testing.T) {
 			e, envPath := newTestHostEnv(t)
-			require.NoError(t, os.WriteFile(envPath, []byte(content), 0o600))
+			require.NoError(t, os.WriteFile(envPath, []byte("APPLIED=before-error\n"+content), 0o600))
 
 			env := map[string]string{}
 			err := parseEnvFile(e, envPath, &env, false)(t.Context())
 			require.Error(t, err)
 			assert.Contains(t, err.Error(), "delimiter")
-			assert.Empty(t, env)
+			assert.Equal(t, map[string]string{"APPLIED": "before-error"}, env)
 		})
 	}
 }

act/container/tar.go

@@ -36,7 +36,7 @@ func writeFilesTar(ctx context.Context, w io.Writer, uid, gid int, files ...*Fil
 }
 
 // writeDirTar prefixes entries with dstPath for extraction at root.
-func writeDirTar(ctx context.Context, w io.Writer, dstPath, srcPath string, useGitIgnore, skipGitDir bool, uid, gid int) error {
+func writeDirTar(ctx context.Context, w io.Writer, dstPath, srcPath string, useGitIgnore, skipGitDir bool, uid, gid int, executable bool) error {
 	logger := common.Logger(ctx)
 	tw := tar.NewWriter(w)
 	srcPrefix := strings.TrimSuffix(filepath.Dir(srcPath), string(filepath.Separator)) + string(filepath.Separator)
@@ -47,7 +47,7 @@ func writeDirTar(ctx context.Context, w io.Writer, dstPath, srcPath string, useG
 		SrcPrefix:    srcPrefix,
 		SkipGitDir:   skipGitDir,
 		UseGitIgnore: useGitIgnore,
-		Handler:      &filecollector.TarCollector{TarWriter: tw, UID: uid, GID: gid, DstDir: dstPath[1:]},
+		Handler:      &filecollector.TarCollector{TarWriter: tw, UID: uid, GID: gid, DstDir: dstPath[1:], Executable: executable},
 	}).CollectFiles(ctx)); err != nil {
 		return err
 	}

act/filecollector/file_collector.go

@@ -27,22 +27,25 @@ type Handler interface {
 }
 
 type TarCollector struct {
-	TarWriter *tar.Writer
-	UID       int
-	GID       int
-	DstDir    string
+	TarWriter  *tar.Writer
+	UID        int
+	GID        int
+	DstDir     string
+	Executable bool // Windows has no exec bit, so mark everything executable like docker build
 }
 
 func (tc TarCollector) WriteFile(fpath string, fi fs.FileInfo, linkName string, f io.Reader) error {
 	// create a new dir/file header
-	header, err := tar.FileInfoHeader(fi, linkName)
+	header, err := tar.FileInfoHeader(fi, filepath.ToSlash(linkName))
 	if err != nil {
 		return err
 	}
 
 	// update the name to correctly reflect the desired destination when untaring
 	header.Name = path.Join(tc.DstDir, fpath)
-	header.Mode = int64(fi.Mode())
+	if tc.Executable {
+		header.Mode = header.Mode&0o755 | 0o111
+	}
 	header.Uid = tc.UID
 	header.Gid = tc.GID
 

act/filecollector/file_collector_test.go

@@ -54,6 +54,7 @@ func TestCollectFilesKeepsWhatGitTracksOrDoesNotIgnore(t *testing.T) {
 	}
 	expected := map[string]string{".gitignore": "", "ign/tracked": "", "nested/kept": "", "renamed": "", "sub/.gitignore": "", "sub/kept": ""}
 	if runtime.GOOS != "windows" {
+		require.NoError(t, os.Chmod(filepath.Join(repoDir, "renamed"), 0o777|os.ModeSticky))
 		require.NoError(t, os.Symlink(".env", filepath.Join(repoDir, "test.env")))
 		expected["test.env"] = ".env"
 	}
@@ -69,6 +70,9 @@ func TestCollectFilesKeepsWhatGitTracksOrDoesNotIgnore(t *testing.T) {
 	for header, err := tr.Next(); err != io.EOF; header, err = tr.Next() {
 		require.NoError(t, err)
 		files[header.Name] = header.Linkname
+		if header.Name == "renamed" && runtime.GOOS != "windows" {
+			assert.Equal(t, int64(0o1777), header.Mode)
+		}
 	}
 	assert.Contains(t, files, ".git/HEAD")
 	maps.DeleteFunc(files, func(name, _ string) bool { return strings.Contains("/"+name, "/.git/") })

act/lookpath/git_bash.go

@@ -0,0 +1,25 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package lookpath
+
+import (
+	"path/filepath"
+	"strings"
+)
+
+func lookPathWindows(file string, env map[string]string, lookup func(string, map[string]string) (string, error)) (string, error) {
+	found, err := lookup(file, env)
+	isBash := strings.EqualFold(file, "bash") || strings.EqualFold(file, "bash.exe")
+	if !isBash || err == nil && !strings.EqualFold(filepath.Base(filepath.Dir(found)), "System32") { // System32's bash is the WSL launcher, Git's bash replaces it
+		return found, err
+	}
+	if git, gitErr := lookup("git.exe", env); gitErr == nil {
+		for _, relative := range []string{"../bin/bash.exe", "../usr/bin/bash.exe", "bash.exe"} {
+			if bash, bashErr := lookup(filepath.Join(filepath.Dir(git), relative), env); bashErr == nil {
+				return bash, nil
+			}
+		}
+	}
+	return found, err
+}

act/lookpath/git_bash_test.go

@@ -0,0 +1,56 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package lookpath
+
+import (
+	"io/fs"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestLookPathWindowsFallsBackToGitBash(t *testing.T) {
+	root := "C:" + string(filepath.Separator)
+	system32 := filepath.Join(root, "Windows", "System32")
+	gitCmd, gitBin := filepath.Join(root, "Git", "cmd"), filepath.Join(root, "Git", "bin")
+	msys := filepath.Join(root, "msys64", "usr", "bin")
+	for _, test := range []struct {
+		name, command, want string
+		path                []string
+	}{
+		{"wsl launcher first", "bash", filepath.Join(gitBin, "bash.exe"), []string{system32, gitCmd}},
+		{"no bash on path", "BASH.EXE", filepath.Join(gitBin, "bash.exe"), []string{gitCmd}},
+		{"own bash first", "bash", filepath.Join(msys, "bash.exe"), []string{msys, system32, gitCmd}},
+		{"no git", "bash", filepath.Join(system32, "bash.exe"), []string{system32}},
+		{"other command", "sh", filepath.Join(system32, "sh.exe"), []string{system32, gitCmd}},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			files := map[string]bool{
+				filepath.Join(system32, "bash.exe"): true, filepath.Join(system32, "sh.exe"): true,
+				filepath.Join(gitCmd, "git.exe"): true, filepath.Join(gitBin, "bash.exe"): true, filepath.Join(msys, "bash.exe"): true,
+			}
+			lookup := func(file string, env map[string]string) (string, error) {
+				candidates := []string{file}
+				if !strings.ContainsAny(file, `:\/`) {
+					candidates = nil
+					for directory := range strings.SplitSeq(env["PATH"], ";") {
+						candidates = append(candidates, filepath.Join(directory, strings.TrimSuffix(strings.ToLower(file), ".exe")+".exe"))
+					}
+				}
+				for _, candidate := range candidates {
+					if files[filepath.Clean(candidate)] {
+						return filepath.Clean(candidate), nil
+					}
+				}
+				return "", fs.ErrNotExist
+			}
+			got, err := lookPathWindows(test.command, map[string]string{"PATH": strings.Join(test.path, ";")}, lookup)
+			require.NoError(t, err)
+			assert.Equal(t, test.want, got)
+		})
+	}
+}

act/lookpath/lp_windows.go

@@ -53,6 +53,10 @@ func findExecutable(file string, exts []string) (string, error) {
 // a suitable candidate.
 // The result may be an absolute path or a path relative to the current directory.
 func LookPath2(file string, env map[string]string) (string, error) {
+	return lookPathWindows(file, env, lookPath)
+}
+
+func lookPath(file string, env map[string]string) (string, error) {
 	var exts []string
 	x := getenv(env, `PATHEXT`)
 	if x != "" {

act/runner/action.go

@@ -198,7 +198,7 @@ func runActionImpl(step actionStep, actionDir string, remoteAction *remoteAction
 			if err := maybeCopyToActionDir(ctx, step, actionDir, actionPath, containerActionDir); err != nil {
 				return err
 			}
-			containerArgs := nodeActionCommand(path.Join(containerActionDir, action.Runs.Main))
+			containerArgs := nodeActionCommand(container.JoinPath(containerActionDir, action.Runs.Main))
 			logger.Debugf("executing remote job container: %s", containerArgs)
 
 			rc.ApplyExtraPath(ctx, step.getEnv())
@@ -226,7 +226,7 @@ func runActionImpl(step actionStep, actionDir string, remoteAction *remoteAction
 			execFileName := action.Runs.Main + ".out"
 			return common.NewPipelineExecutor(
 				rc.JobContainer.Exec([]string{"go", "build", "-o", execFileName, action.Runs.Main}, *step.getEnv(), "", containerActionDir),
-				rc.JobContainer.Exec([]string{filepath.Join(containerActionDir, execFileName)}, *step.getEnv(), "", ""),
+				rc.JobContainer.Exec([]string{container.JoinPath(containerActionDir, execFileName)}, *step.getEnv(), "", ""),
 			)(ctx)
 		default:
 			return fmt.Errorf("the runs.using key must be one of: %v, got %s", []string{
@@ -295,6 +295,9 @@ func (rc *RunContext) dockerActionImage(ctx context.Context, step actionStep, ac
 func execAsDocker(ctx context.Context, step actionStep, actionName, actionDir, basedir string, localAction bool, stage stepStage) error {
 	logger := common.Logger(ctx)
 	rc := step.getRunContext()
+	if rc.isWindowsHost() {
+		return errWindowsHostContainer
+	}
 	action := step.getActionModel()
 	if rc.kubernetes {
 		return errKubernetesDocker
@@ -525,22 +528,8 @@ func populateEnvsFromInput(ctx context.Context, step step, action *model.Action)
 	return nil
 }
 
-// lookupFold finds name in values, ignoring case where the environment does, as GitHub's inputs always do.
-func lookupFold[V any](values map[string]V, name string, caseInsensitive bool) (V, bool) {
-	if value, ok := values[name]; ok || !caseInsensitive {
-		return value, ok
-	}
-	for key, value := range values {
-		if strings.EqualFold(key, name) {
-			return value, true
-		}
-	}
-	var zero V
-	return zero, false
-}
-
 func stepInput(step *model.Step, name string) string {
-	value, _ := lookupFold(step.With, name, true)
+	value, _ := common.LookupFold(step.With, name, true)
 	return value
 }
 
@@ -548,7 +537,7 @@ func warnUnexpectedInputs(ctx context.Context, action *model.Action, inputs map[
 	docker := action.Runs.Using.IsDocker()
 	var unexpectedInputs []string
 	for input := range inputs {
-		_, declared := lookupFold(action.Inputs, input, true)
+		_, declared := common.LookupFold(action.Inputs, input, true)
 		containerInput := docker && (strings.EqualFold(input, "entryPoint") || strings.EqualFold(input, "args"))
 		if !declared && !containerInput {
 			unexpectedInputs = append(unexpectedInputs, input)
@@ -665,7 +654,7 @@ func runPreStep(step actionStep) common.Executor {
 				return err
 			}
 
-			containerArgs := nodeActionCommand(path.Join(containerActionDir, action.Runs.Pre))
+			containerArgs := nodeActionCommand(container.JoinPath(containerActionDir, action.Runs.Pre))
 			logger.Debugf("executing remote job container: %s", containerArgs)
 
 			rc.ApplyExtraPath(ctx, step.getEnv())
@@ -697,7 +686,7 @@ func runPreStep(step actionStep) common.Executor {
 			execFileName := action.Runs.Pre + ".out"
 			return common.NewPipelineExecutor(
 				rc.JobContainer.Exec([]string{"go", "build", "-o", execFileName, action.Runs.Pre}, *step.getEnv(), "", containerActionDir),
-				rc.JobContainer.Exec([]string{filepath.Join(containerActionDir, execFileName)}, *step.getEnv(), "", ""),
+				rc.JobContainer.Exec([]string{container.JoinPath(containerActionDir, execFileName)}, *step.getEnv(), "", ""),
 			)(ctx)
 		default:
 			return nil
@@ -765,7 +754,7 @@ func runPostStep(step actionStep) common.Executor {
 
 			populateEnvsFromSavedState(step.getEnv(), step, rc)
 
-			containerArgs := nodeActionCommand(path.Join(containerActionDir, action.Runs.Post))
+			containerArgs := nodeActionCommand(container.JoinPath(containerActionDir, action.Runs.Post))
 			logger.Debugf("executing remote job container: %s", containerArgs)
 
 			rc.ApplyExtraPath(ctx, step.getEnv())
@@ -794,7 +783,7 @@ func runPostStep(step actionStep) common.Executor {
 			execFileName := action.Runs.Post + ".out"
 			return common.NewPipelineExecutor(
 				rc.JobContainer.Exec([]string{"go", "build", "-o", execFileName, action.Runs.Post}, *step.getEnv(), "", containerActionDir),
-				rc.JobContainer.Exec([]string{filepath.Join(containerActionDir, execFileName)}, *step.getEnv(), "", ""),
+				rc.JobContainer.Exec([]string{container.JoinPath(containerActionDir, execFileName)}, *step.getEnv(), "", ""),
 			)(ctx)
 
 		default:

act/runner/action_test.go

@@ -115,7 +115,7 @@ runs:
 					"cwd": {
 						Description: "(Actual working directory)",
 						Required:    false,
-						Default:     "actionDir/actionPath",
+						Default:     filepath.Join("actionDir", "actionPath"),
 					},
 					"command": {
 						Description: "(Actual program)",
@@ -144,7 +144,7 @@ runs:
 			}
 
 			writeFile := func(filename string, _data []byte, perm fs.FileMode) error {
-				assert.Equal(t, "actionDir/actionPath/trampoline.js", filename)
+				assert.Equal(t, filepath.Join("actionDir", "actionPath", "trampoline.js"), filename)
 				assert.Equal(t, fs.FileMode(0o644), perm)
 				return nil
 			}
@@ -248,6 +248,39 @@ func TestActionRunner(t *testing.T) {
 	}
 }
 
+func TestGoActionUsesLinuxExecutablePaths(t *testing.T) {
+	for _, stage := range []string{"main", "pre", "post"} {
+		t.Run(stage, func(t *testing.T) {
+			cm := &containerMock{}
+			containerActionDir := "/var/run/act/actions/" + model.UsesHash("/org/repo@ref")
+			cm.On("CopyDir", containerActionDir+"/", mock.Anything, false, true).Return(noopExecutor).Maybe()
+			cm.On("Exec", []string{"go", "build", "-o", stage + ".go.out", stage + ".go"}, mock.Anything, "", containerActionDir).Return(noopExecutor).Once()
+			cm.On("Exec", []string{containerActionDir + "/" + stage + ".go.out"}, mock.Anything, "", "").Return(noopExecutor).Once()
+			step := &stepActionRemote{
+				Step: &model.Step{ID: "step", Uses: "org/repo@ref"},
+				RunContext: &RunContext{
+					Config:       &Config{NoActionPatch: true, PresetGitHubContext: &model.GithubContext{}},
+					Run:          &model.Run{JobID: "job", Workflow: &model.Workflow{Jobs: map[string]*model.Job{"job": {}}}},
+					JobContainer: cm,
+				},
+				action:       &model.Action{Runs: model.ActionRuns{Using: model.ActionRunsUsingGo, Main: "main.go", Pre: "pre.go", Post: "post.go"}},
+				actionDir:    t.TempDir(),
+				env:          map[string]string{},
+				remoteAction: mustNewRemoteAction(t, "org/repo@ref"),
+			}
+			switch stage {
+			case "main":
+				require.NoError(t, runActionImpl(step, step.actionDir, step.remoteAction)(t.Context()))
+			case "pre":
+				require.NoError(t, runPreStep(step)(t.Context()))
+			case "post":
+				require.NoError(t, runPostStep(step)(t.Context()))
+			}
+			cm.AssertExpectations(t)
+		})
+	}
+}
+
 func TestNodeActionCommandPreservesSymlinkedEntrypoint(t *testing.T) {
 	if runtime.GOOS == "windows" {
 		t.Skip("symlink creation requires privileges on Windows")

act/runner/command.go

@@ -165,7 +165,7 @@ func (rc *RunContext) refuseUnsecureCommand(ctx context.Context, command string)
 	}
 	caseInsensitive := rc.JobContainer != nil && rc.JobContainer.IsEnvironmentCaseInsensitive()
 	for _, env := range []map[string]string{rc.currentStepEnv(), rc.Env, rc.GlobalEnv} {
-		if value, ok := lookupFold(env, allowUnsecureCommandsVar, caseInsensitive); ok {
+		if value, ok := common.LookupFold(env, allowUnsecureCommandsVar, caseInsensitive); ok {
 			if isTruthyEnv(value) {
 				return false
 			}

act/runner/expression.go

@@ -10,7 +10,6 @@ import (
 	"errors"
 	"fmt"
 	"maps"
-	"path"
 	"reflect"
 	"regexp"
 	"strings"
@@ -160,7 +159,7 @@ func getHashFilesFunction(ctx context.Context, rc *RunContext) func(v []reflect.
 				Name: name,
 				Mode: 0o644,
 				Body: hashfiles,
-			}).Then(rc.JobContainer.Exec([]string{"node", path.Join(rc.JobContainer.GetActPath(), name)}, env, "", ""))(timeoutCtx)
+			}).Then(rc.JobContainer.Exec([]string{"node", container.JoinPath(rc.JobContainer.GetActPath(), name)}, env, "", ""))(timeoutCtx)
 			quotedPatterns := expressionStringEscape(strings.Join(patterns, ", "))
 			switch {
 			case err == nil:

act/runner/job_executor.go

@@ -23,6 +23,7 @@ import (
 	"sync"
 	"time"
 	"unicode"
+	"unicode/utf8"
 
 	"gitea.com/gitea/runner/act/common"
 	"gitea.com/gitea/runner/act/common/logging"
@@ -30,6 +31,8 @@ import (
 
 	"gitea.dev/actionslib/pkg/exprparser"
 	"gitea.dev/actionslib/pkg/model"
+	unicodeencoding "golang.org/x/text/encoding/unicode"
+	"golang.org/x/text/transform"
 )
 
 const (
@@ -461,7 +464,7 @@ func evaluateJobEnv(ctx context.Context, rc *RunContext) (map[string]string, err
 		}
 	}
 	if workflowEnv != nil {
-		evaluated = mergeMaps(workflowEnv, env)
+		evaluated = rc.mergeEnv(workflowEnv, env)
 		evaluator = rc.NewExpressionEvaluatorWithEnv(ctx, evaluated)
 	}
 	var err error
@@ -569,14 +572,34 @@ func tryUploadJobSummary(ctx context.Context, rc *RunContext) {
 	actPath := rc.JobContainer.GetActPath()
 	// Reuse a single client across all step uploads so connections can be pooled.
 	client := &http.Client{Timeout: jobSummaryUploadRequestTimeout, Transport: rc.Config.instanceTransportFor(base)}
+	maskers := rc.secretMaskers()
+	longestMask := 0
+	for i := 0; i < len(maskers); i += 2 {
+		longestMask = max(longestMask, len(maskers[i]))
+	}
+	masker := NewSecretReplacer(maskers)
+	limit := maxJobSummaryBytes + longestMask
 	for i := range rc.Run.Job().Steps {
-		summaryPath := path.Join(actPath, "workflow", "step-summary-"+strconv.Itoa(i)+".md")
-		body, ok := readSingleFileFromContainerArchive(ctx, rc.JobContainer, summaryPath, maxJobSummaryBytes)
+		summaryPath := container.JoinPath(actPath, "workflow", "step-summary-"+strconv.Itoa(i)+".md")
+		body, ok := readSingleFileFromContainerArchive(ctx, rc.JobContainer, summaryPath, int64(limit+1))
 		if !ok || len(body) == 0 {
 			continue
 		}
-		// Gitea renders summaries on the run page, so mask before the upload.
-		uploadJobSummary(ctx, client, base+strconv.Itoa(i)+"/summary", runtimeToken, []byte(rc.maskSecrets(string(body))))
+		masked := masker.Replace(string(body))
+		split := len(body) > limit
+		if split { // the read can end inside a secret, so keep only what masks alike without the lookahead
+			unsplit := masker.Replace(string(body[:maxJobSummaryBytes]))
+			kept := 0
+			for kept < len(unsplit) && kept < len(masked) && unsplit[kept] == masked[kept] {
+				kept++
+			}
+			for kept > 0 && kept < len(masked) && !utf8.RuneStart(masked[kept]) {
+				kept--
+			}
+			masked = masked[:kept]
+		}
+		body = truncateJobSummary(ctx, []byte(masked), summaryPath, maxJobSummaryBytes, split)
+		uploadJobSummary(ctx, client, base+strconv.Itoa(i)+"/summary", runtimeToken, body)
 	}
 }
 
@@ -690,26 +713,26 @@ func readSingleFileFromContainerArchive(ctx context.Context, env container.Execu
 		if entryName != requestedPath && entryName != path.Base(requestedPath) {
 			continue
 		}
-		// Summaries larger than the limit are truncated rather than dropped, so the
-		// user still gets the leading content (mirroring how GitHub caps oversized
-		// step summaries instead of discarding them). Read one extra byte so an
-		// over-limit file is detected from the actual stream rather than trusting
-		// header.Size, then cap the returned content at maxBytes.
-		b, err := io.ReadAll(io.LimitReader(tr, maxBytes+1))
+		b, err := io.ReadAll(io.LimitReader(transform.NewReader(tr, unicodeencoding.BOMOverride(unicodeencoding.UTF8.NewDecoder())), maxBytes))
 		if err != nil {
 			return nil, false
 		}
-		if int64(len(b)) > maxBytes {
-			// Reserve room for the marker so the marked-up result still fits in maxBytes.
-			marker := []byte(jobSummaryTruncationMarker)
-			keep := max(maxBytes-int64(len(marker)), 0)
-			b = append(b[:keep], marker...)
-			common.Logger(ctx).Warnf("job summary truncated: path=%s max=%d", p, maxBytes)
-		}
 		return b, true
 	}
 }
 
+func truncateJobSummary(ctx context.Context, body []byte, summaryPath string, maxBytes int, split bool) []byte {
+	if !split && len(body) <= maxBytes {
+		return body
+	}
+	keep := max(min(len(body), maxBytes-len(jobSummaryTruncationMarker)), 0)
+	for keep > 0 && keep < len(body) && !utf8.RuneStart(body[keep]) {
+		keep--
+	}
+	common.Logger(ctx).Warnf("job summary truncated: path=%s max=%d", summaryPath, maxBytes)
+	return append(body[:keep], jobSummaryTruncationMarker...)
+}
+
 // useJobStageLogger tags the log entries of a job level executor with the stage they belong to.
 func useJobStageLogger(stage string, executor common.Executor) common.Executor {
 	return func(ctx context.Context) error {

act/runner/job_executor_test.go

@@ -34,6 +34,8 @@ import (
 	"github.com/stretchr/testify/mock"
 	"github.com/stretchr/testify/require"
 	yaml "go.yaml.in/yaml/v4"
+	"golang.org/x/text/encoding"
+	"golang.org/x/text/encoding/unicode"
 )
 
 func TestJobExecutor(t *testing.T) {
@@ -932,49 +934,42 @@ func TestExtractJobIDFromRuntimeToken(t *testing.T) {
 	assert.Equal(t, int64(0), extractJobIDFromRuntimeToken(""))
 }
 
-func TestReadSingleFileFromContainerArchiveFindsMatchingRegularFile(t *testing.T) {
-	ctx := t.Context()
-	cm := &containerMock{}
-	cm.On("GetContainerArchive", ctx, "/var/run/act/workflow/SUMMARY.md").Return(
-		io.NopCloser(bytes.NewReader(tarArchive(t,
-			tarEntry{name: "workflow", typeflag: tar.TypeDir},
-			tarEntry{name: "other.md", body: "wrong"},
-			tarEntry{name: "SUMMARY.md", body: "right"},
-		))),
-		nil,
-	).Once()
-
-	body, ok := readSingleFileFromContainerArchive(ctx, cm, "/var/run/act/workflow/SUMMARY.md", 1024)
-
-	assert.True(t, ok)
-	assert.Equal(t, []byte("right"), body)
-	cm.AssertExpectations(t)
-}
-
-func TestReadSingleFileFromContainerArchiveSizeLimit(t *testing.T) {
+func TestReadSingleFileFromContainerArchive(t *testing.T) {
+	retainedBytes := 200 - len(jobSummaryTruncationMarker)
 	for name, tt := range map[string]struct {
 		content  string
 		maxBytes int64
 		want     string
 	}{
-		"truncates oversized summary": {strings.Repeat("a", 300), 200, strings.Repeat("a", 200-len(jobSummaryTruncationMarker)) + jobSummaryTruncationMarker},
-		"keeps exact limit":           {"abc", 3, "abc"},
+		"truncates oversized summary without reading entire file": {strings.Repeat("a", 100000), 200, strings.Repeat("a", 200-len(jobSummaryTruncationMarker)) + jobSummaryTruncationMarker},
+		"keeps exact limit":               {"abc", 3, "abc"},
+		"strips UTF-8 BOM before limit":   {"\xef\xbb\xbfabc", 3, "abc"},
+		"decodes UTF-16 before limit":     {"\xff\xfea\x00b\x00c\x00", 3, "abc"},
+		"limits expanded UTF-16":          {"\xff\xfe" + strings.Repeat("\x2d\x4e", 150), 200, strings.Repeat("中", retainedBytes/3) + jobSummaryTruncationMarker},
+		"keeps complete UTF-8 characters": {strings.Repeat("a", retainedBytes-1) + "€" + strings.Repeat("a", 200), 200, strings.Repeat("a", retainedBytes-1) + jobSummaryTruncationMarker},
 	} {
 		t.Run(name, func(t *testing.T) {
 			logger, hook := logtest.NewLogger()
 			ctx := common.WithLogger(t.Context(), logger)
 			cm := &containerMock{}
+			archive := bytes.NewReader(tarArchive(t,
+				tarEntry{name: "workflow", typeflag: tar.TypeDir},
+				tarEntry{name: "other.md", body: "wrong"},
+				tarEntry{name: "SUMMARY.md", body: tt.content},
+			))
 			cm.On("GetContainerArchive", ctx, "/var/run/act/workflow/SUMMARY.md").Return(
-				io.NopCloser(bytes.NewReader(tarArchive(t, tarEntry{name: "SUMMARY.md", body: tt.content}))),
+				io.NopCloser(archive),
 				nil,
 			).Once()
 
-			body, ok := readSingleFileFromContainerArchive(ctx, cm, "/var/run/act/workflow/SUMMARY.md", tt.maxBytes)
+			body, ok := readSingleFileFromContainerArchive(ctx, cm, "/var/run/act/workflow/SUMMARY.md", tt.maxBytes+1)
+			assert.LessOrEqual(t, int64(len(body)), tt.maxBytes+1)
+			body = truncateJobSummary(ctx, body, "/var/run/act/workflow/SUMMARY.md", int(tt.maxBytes), false)
 
 			assert.True(t, ok)
 			assert.Equal(t, []byte(tt.want), body)
 			assert.LessOrEqual(t, int64(len(body)), tt.maxBytes)
-			if int64(len(tt.content)) > tt.maxBytes {
+			if strings.HasSuffix(tt.want, jobSummaryTruncationMarker) {
 				if assert.Len(t, hook.AllRecords(), 1) {
 					assert.Contains(t, hook.LastRecord().Message, "job summary truncated")
 				}
@@ -1113,35 +1108,75 @@ func TestJobSetContinueOnError(t *testing.T) {
 }
 
 func TestTryUploadJobSummaryMasksSecrets(t *testing.T) {
-	var got string
-	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		body, err := io.ReadAll(r.Body)
-		assert.NoError(t, err)
-		got = string(body)
-		w.WriteHeader(http.StatusNoContent)
-	}))
-	defer server.Close()
+	const prefix = "deployed true with s3cr3t and runtime-added via pr0xypw 😀"
+	const maskedPrefix = "deployed true with *** and *** via *** 😀"
+	padding := strings.Repeat("a", maxJobSummaryBytes-len(jobSummaryTruncationMarker)-len(prefix)-2)
+	content := prefix + padding + "s3cr3t" + strings.Repeat("中", 100)
+	want := maskedPrefix + padding + "***" + strings.Repeat("中", (len(prefix)-len(maskedPrefix)-1)/3) + jobSummaryTruncationMarker
+	longSecret := "PREFIX" + strings.Repeat("xy", 100) + "Z"
+	readLimit := maxJobSummaryBytes + base64.StdEncoding.EncodedLen(len(longSecret)) + 1
+	shrinkingPrefix := strings.Repeat(longSecret, (readLimit-len(longSecret)+1)/len(longSecret))
+	for name, testcase := range map[string]struct {
+		encoding      encoding.Encoding
+		content, want string
+		masks         []string
+	}{
+		"UTF-8":                    {unicode.UTF8, content, want, nil},
+		"UTF-8 BOM":                {unicode.UTF8BOM, content, want, nil},
+		"UTF-16LE BOM":             {unicode.UTF16(unicode.LittleEndian, unicode.UseBOM), content, want, nil},
+		"UTF-16BE BOM":             {unicode.UTF16(unicode.BigEndian, unicode.UseBOM), content, want, nil},
+		"secret split by the read": {unicode.UTF8, strings.Repeat("s3cr3t", maxJobSummaryBytes/3), "", nil},
+		"split read keeps every masked secret before the limit": {
+			unicode.UTF8,
+			"# public\n" + strings.Repeat(longSecret, readLimit/len(longSecret)+1),
+			"# public\n" + strings.Repeat("***", (maxJobSummaryBytes-len("# public\n"))/len(longSecret)) + jobSummaryTruncationMarker,
+			[]string{longSecret},
+		},
+		"nested secret expands the split tail": {
+			unicode.UTF8,
+			shrinkingPrefix + strings.Repeat("*", readLimit-len(shrinkingPrefix)-len(longSecret)+1) + longSecret,
+			"",
+			[]string{"xy", longSecret},
+		},
+	} {
+		t.Run(name, func(t *testing.T) {
+			var got string
+			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				body, err := io.ReadAll(r.Body)
+				assert.NoError(t, err)
+				got = string(body)
+				w.WriteHeader(http.StatusNoContent)
+			}))
+			defer server.Close()
 
-	cm := &containerMock{}
-	cm.On("GetContainerArchive", mock.Anything, "/var/run/act/workflow/step-summary-0.md").Return(
-		io.NopCloser(bytes.NewReader(tarArchive(t, tarEntry{
-			name: "step-summary-0.md", body: "deployed true with s3cr3t and runtime-added via pr0xypw",
-		}))),
-		nil,
-	).Once()
+			content, err := testcase.encoding.NewEncoder().Bytes([]byte(testcase.content))
+			require.NoError(t, err)
+			cm := &containerMock{}
+			cm.On("GetContainerArchive", mock.Anything, "/var/run/act/workflow/step-summary-0.md").Return(
+				io.NopCloser(bytes.NewReader(tarArchive(t, tarEntry{
+					name: "step-summary-0.md", body: string(content),
+				}))),
+				nil,
+			).Once()
 
-	rc := newJobSummaryRC(map[string]string{
-		"GITEA_ACTIONS_CAPABILITIES": "job-summary",
-		"ACTIONS_RUNTIME_URL":        server.URL,
-		"ACTIONS_RUNTIME_TOKEN":      fakeRuntimeToken(34),
-		"GITEA_RUN_ID":               "12",
-	}, cm, 1)
-	rc.Config.Secrets = map[string]string{"TOK": "s3cr3t", "ACTIONS_STEP_DEBUG": "true"}
-	rc.Config.ExtraMasks = []string{"pr0xypw"}
-	rc.Masks = []string{"runtime-added"}
+			rc := newJobSummaryRC(map[string]string{
+				"GITEA_ACTIONS_CAPABILITIES": "job-summary",
+				"ACTIONS_RUNTIME_URL":        server.URL,
+				"ACTIONS_RUNTIME_TOKEN":      fakeRuntimeToken(34),
+				"GITEA_RUN_ID":               "12",
+			}, cm, 1)
+			rc.Config.Secrets = map[string]string{"TOK": "s3cr3t", "ACTIONS_STEP_DEBUG": "true"}
+			rc.Config.ExtraMasks = append([]string{"pr0xypw"}, testcase.masks...)
+			rc.Masks = []string{"runtime-added"}
 
-	tryUploadJobSummary(t.Context(), rc)
+			tryUploadJobSummary(t.Context(), rc)
 
-	assert.Equal(t, "deployed true with *** and *** via ***", got)
-	cm.AssertExpectations(t)
+			if testcase.want == "" {
+				assert.Equal(t, jobSummaryTruncationMarker, strings.TrimLeft(got, "*"))
+			} else {
+				assert.Equal(t, testcase.want, got)
+			}
+			cm.AssertExpectations(t)
+		})
+	}
 }

act/runner/job_hooks.go

@@ -82,8 +82,8 @@ func (rc *RunContext) runJobHook(ctx context.Context, hookPath, name string) err
 // the first one wrote.
 func (rc *RunContext) setupHookFileCommands(ctx context.Context, env map[string]string) error {
 	actPath := rc.JobContainer.GetActPath()
-	env["GITHUB_ENV"] = path.Join(actPath, hookEnvFileCommand)
-	env["GITHUB_PATH"] = path.Join(actPath, hookPathFileCommand)
+	env["GITHUB_ENV"] = container.JoinPath(actPath, hookEnvFileCommand)
+	env["GITHUB_PATH"] = container.JoinPath(actPath, hookPathFileCommand)
 	aliasGiteaEnv(env)
 
 	return rc.JobContainer.Copy(actPath,
@@ -94,7 +94,7 @@ func (rc *RunContext) setupHookFileCommands(ctx context.Context, env map[string]
 
 func (rc *RunContext) processHookFileCommands(ctx context.Context) error {
 	err := processRunnerEnvFileCommand(ctx, hookEnvFileCommand, rc, rc.setEnvFile)
-	if pathErr := rc.UpdateExtraPath(ctx, path.Join(rc.JobContainer.GetActPath(), hookPathFileCommand)); pathErr != nil && err == nil {
+	if pathErr := rc.UpdateExtraPath(ctx, container.JoinPath(rc.JobContainer.GetActPath(), hookPathFileCommand)); pathErr != nil && err == nil {
 		err = pathErr
 	}
 	return err
@@ -109,7 +109,7 @@ func hookCommand(hookPath string) (cmd []string, shell string) {
 	case ".sh":
 		return []string{"bash", "-e", hookPath}, "bash -e {0}"
 	case ".ps1":
-		return []string{"pwsh", "-command", ". '" + hookPath + "'"}, `pwsh -command ". '{0}'"`
+		return []string{"pwsh", "-command", ". '" + expressionStringEscape(hookPath) + "'"}, `pwsh -command ". '{0}'"`
 	default:
 		return []string{hookPath}, ""
 	}

act/runner/job_hooks_test.go

@@ -246,9 +246,10 @@ func TestHookCommand(t *testing.T) {
 		cmd   []string
 		shell string
 	}{
-		"/hooks/started.sh":  {[]string{"bash", "-e", "/hooks/started.sh"}, "bash -e {0}"},
-		"/hooks/started.PS1": {[]string{"pwsh", "-command", ". '/hooks/started.PS1'"}, `pwsh -command ". '{0}'"`},
-		"/hooks/started":     {[]string{"/hooks/started"}, ""},
+		"/hooks/started.sh":            {[]string{"bash", "-e", "/hooks/started.sh"}, "bash -e {0}"},
+		"/hooks/started.PS1":           {[]string{"pwsh", "-command", ". '/hooks/started.PS1'"}, `pwsh -command ". '{0}'"`},
+		"/hooks/started":               {[]string{"/hooks/started"}, ""},
+		`C:\hooks\O'Brien\started.ps1`: {[]string{"pwsh", "-command", `. 'C:\hooks\O''Brien\started.ps1'`}, `pwsh -command ". '{0}'"`},
 	} {
 		cmd, shell := hookCommand(hookPath)
 		assert.Equal(t, want.cmd, cmd, hookPath)

act/runner/logger.go

@@ -479,11 +479,15 @@ func (f textFormatter) isColored() bool {
 // such as a container name or a job summary. Masks added at runtime count, so a summary written
 // after ::add-mask:: is covered too.
 func (rc *RunContext) maskSecrets(value string) string {
+	return NewSecretReplacer(rc.secretMaskers()).Replace(value)
+}
+
+func (rc *RunContext) secretMaskers() []string {
 	oldnew := rc.Config.maskers()
 	for _, mask := range rc.Masks {
 		oldnew = AppendSecretMasker(oldnew, mask)
 	}
-	return NewSecretReplacer(oldnew).Replace(value)
+	return oldnew
 }
 
 // maskers is every value this job's configuration says to hide, whatever the sink.

act/runner/patch_actions_test.go

@@ -256,7 +256,7 @@ func TestActionScriptPaths(t *testing.T) {
 }
 
 func TestPatchActionsAtTheContainerCopy(t *testing.T) {
-	copiedBundles := func(t *testing.T, noPatch bool) ([]string, []*container.FileEntry) {
+	copiedBundles := func(t *testing.T, noPatch bool) ([]string, []*container.FileEntry, int64) {
 		t.Helper()
 
 		cm := &containerMock{}
@@ -274,6 +274,8 @@ func TestPatchActionsAtTheContainerCopy(t *testing.T) {
 		require.NoError(t, os.MkdirAll(filepath.Dir(script), 0o755))
 		require.NoError(t, os.WriteFile(filepath.Join(filepath.Dir(script), "index.js"), []byte("require('./cache.js')"), 0o600))
 		require.NoError(t, os.WriteFile(script, []byte(gateTSC), 0o600))
+		info, err := os.Stat(script)
+		require.NoError(t, err)
 
 		var calls []string
 		var copied []*container.FileEntry
@@ -291,22 +293,22 @@ func TestPatchActionsAtTheContainerCopy(t *testing.T) {
 		source, err := os.ReadFile(script)
 		require.NoError(t, err)
 		assert.Equal(t, gateTSC, string(source), "the shared copy is never written")
-		return calls, copied
+		return calls, copied, int64(info.Mode().Perm())
 	}
 
 	t.Run("patched over the container's copy", func(t *testing.T) {
-		calls, copied := copiedBundles(t, false)
+		calls, copied, mode := copiedBundles(t, false)
 		assert.Equal(t, []string{"CopyDir", "Copy"}, calls)
 		require.Len(t, copied, 1)
 		assert.Equal(t, "dist/cache.js", copied[0].Name)
-		assert.Equal(t, int64(0o600), copied[0].Mode)
+		assert.Equal(t, mode, copied[0].Mode)
 		assert.True(t, gateOpened(copied[0].Body))
 	})
 
 	// The escape hatch, for an action the edit breaks: the artifact actions refuse again, and the
 	// cache client keeps to v1.
 	t.Run("as shipped when the runner is told not to patch", func(t *testing.T) {
-		calls, copied := copiedBundles(t, true)
+		calls, copied, _ := copiedBundles(t, true)
 		assert.Equal(t, []string{"CopyDir"}, calls)
 		assert.Empty(t, copied)
 	})

act/runner/reusable_workflow_test.go

@@ -160,8 +160,9 @@ func TestCloneRemoteReusableWorkflowSendsInstanceTokenAndClientCert(t *testing.T
 		Run: &model.Run{JobID: "j1", Workflow: &model.Workflow{Jobs: map[string]*model.Job{"j1": {}}}},
 	}
 
-	require.Error(t, cloneRemoteReusableWorkflow(rc, server.URL+"/owner/repo", "main", t.TempDir())(t.Context()))
-	require.True(t, gotCert)
+	err = cloneRemoteReusableWorkflow(rc, server.URL+"/owner/repo", "main", t.TempDir())(t.Context())
+	require.Error(t, err)
+	require.True(t, gotCert, "clone failed before receiving a client certificate: %v", err)
 	require.Equal(t, "token", gotToken)
 }
 

act/runner/run_context.go

@@ -81,6 +81,7 @@ type RunContext struct {
 	jobRunDefaults      model.RunDefaults // defaults.run, resolved once at job setup as GitHub does
 	platformImage       string            // container.image or the runs-on pick, resolved once by isEnabled
 	jobIndex, jobTotal  int               // strategy.job-index and job-total, total 0 when unknown
+	trackingID          string            // RUNNER_TRACKING_ID of the job, generated on first use
 	runtimeToken        string            // ACTIONS_RUNTIME_TOKEN of the workflow run, shared with its called workflows and composite actions
 
 	jobEnv             map[string]string          // workflow and job env as evaluated for the container and service specs
@@ -191,7 +192,7 @@ func (rc *RunContext) GetEnv() map[string]string {
 		if rc.Run != nil && rc.Run.Workflow != nil && rc.Config != nil {
 			job := rc.Run.Job()
 			if job != nil {
-				rc.Env = mergeMaps(rc.Run.Workflow.Env, job.Environment(), rc.Config.Env)
+				rc.Env = rc.mergeEnv(rc.Run.Workflow.Env, job.Environment(), rc.Config.Env)
 			}
 		}
 		if rc.runtimeToken != "" {
@@ -429,27 +430,58 @@ func (rc *RunContext) startHostEnvironment() common.Executor {
 			Workdir:      rc.Config.Workdir,
 			CleanWorkdir: rc.Config.CleanWorkdir,
 			ActPath:      actPath,
-			CleanUp: func() {
-				os.RemoveAll(miscpath)
-			},
-			StdOut:      logWriter,
-			AllocatePTY: rc.Config.AllocatePTY,
+			Root:         miscpath,
+			TrackingID:   rc.runnerTrackingID(),
+			StdOut:       logWriter,
+			AllocatePTY:  rc.Config.AllocatePTY,
 		}
 		rc.cleanUpJobContainer = rc.JobContainer.Remove()
 		rc.setRunnerContextEnv(ctx)
-		for _, env := range os.Environ() {
-			if k, v, ok := strings.Cut(env, "="); ok {
-				// don't override
-				if _, ok := rc.Env[k]; !ok {
-					rc.Env[k] = v
-				}
-			}
-		}
+		rc.importHostEnv(os.Environ())
 
 		return rc.copyWorkflowFiles()(ctx)
 	}
 }
 
+func (rc *RunContext) runnerTrackingID() string {
+	job := rc.topLevelRunContext()
+	if job.trackingID == "" {
+		job.trackingID = "gitea_" + rand.Text()
+	}
+	return job.trackingID
+}
+
+func (rc *RunContext) isEnvCaseInsensitive() bool {
+	if rc.JobContainer != nil {
+		return rc.JobContainer.IsEnvironmentCaseInsensitive()
+	}
+	return runtime.GOOS == "windows" && rc.IsHostEnv()
+}
+
+func (rc *RunContext) importHostEnv(environ []string) {
+	for _, env := range environ {
+		if key, value, ok := strings.Cut(env, "="); ok {
+			if key == "RUNNER_TRACKING_ID" || rc.isEnvCaseInsensitive() && strings.EqualFold(key, "RUNNER_TRACKING_ID") {
+				continue
+			}
+			_, exists := common.LookupFold(rc.Env, key, rc.isEnvCaseInsensitive())
+			if !exists {
+				rc.Env[key] = value
+			}
+		}
+	}
+}
+
+func (rc *RunContext) mergeEnv(envs ...map[string]string) map[string]string {
+	if rc.isEnvCaseInsensitive() {
+		env := map[string]string{}
+		mergeIntoMapCaseInsensitive(env, envs...)
+		return env
+	} else {
+		return mergeMaps(envs...)
+	}
+}
+
 func (rc *RunContext) setRunnerContextEnv(ctx context.Context) {
 	for k, v := range rc.getRunnerContext(ctx) {
 		if v, ok := v.(string); ok {
@@ -460,6 +492,15 @@ func (rc *RunContext) setRunnerContextEnv(ctx context.Context) {
 
 var errKubernetesDocker = errors.New("docker actions and docker:// steps are not supported on Kubernetes")
 
+var errWindowsHostContainer = errors.New("container actions and docker:// steps are not supported in Windows host jobs")
+
+var hostOS = runtime.GOOS // replaced in tests
+
+func (rc *RunContext) isWindowsHost() bool {
+	_, host := rc.JobContainer.(*container.HostEnvironment)
+	return host && hostOS == "windows"
+}
+
 func (rc *RunContext) startKubernetesPod() common.Executor {
 	return func(ctx context.Context) error {
 		if rc.containerSpec.Options != "" || len(rc.containerSpec.Volumes) > 0 || rc.containerSpec.Credentials != nil {
@@ -1311,6 +1352,10 @@ func (rc *RunContext) resolvePlatformImage(ctx context.Context) error {
 	}
 	image, rc.kubernetes = strings.CutPrefix(image, "kubernetes://")
 	rc.platformImage = cmp.Or(rc.containerSpec.Image, image)
+	if rc.isEnvCaseInsensitive() {
+		rc.Env = nil // Rebuild scopes after the host platform is known.
+		rc.GetEnv()
+	}
 	return nil
 }
 
@@ -1509,7 +1554,6 @@ func (rc *RunContext) getGithubContext(ctx context.Context) *model.GithubContext
 		RepositoryOwner:  rc.Config.Env["GITHUB_REPOSITORY_OWNER"],
 		RetentionDays:    cmp.Or(rc.Config.Env["GITHUB_RETENTION_DAYS"], "0"),
 		RunnerPerflog:    cmp.Or(rc.Config.Env["RUNNER_PERFLOG"], "/dev/null"),
-		RunnerTrackingID: rc.Config.Env["RUNNER_TRACKING_ID"],
 		Repository:       rc.Config.Env["GITHUB_REPOSITORY"],
 		Ref:              rc.Config.Env["GITHUB_REF"],
 		Sha:              rc.Config.Env["SHA_REF"],
@@ -1523,6 +1567,8 @@ func (rc *RunContext) getGithubContext(ctx context.Context) *model.GithubContext
 		ghc.EventPath = rc.JobContainer.GetActPath() + "/workflow/event.json"
 	}
 
+	ghc.RunnerTrackingID = rc.runnerTrackingID()
+
 	if preset := rc.Config.PresetGitHubContext; preset != nil {
 		merged := *preset
 		merged.Workflow, merged.Job, merged.Workspace, merged.EventPath = ghc.Workflow, ghc.Job, ghc.Workspace, ghc.EventPath
@@ -1645,7 +1691,9 @@ func (rc *RunContext) withGithubEnv(ctx context.Context, github *model.GithubCon
 	env["GITHUB_REPOSITORY_OWNER"] = github.RepositoryOwner
 	env["GITHUB_RETENTION_DAYS"] = github.RetentionDays
 	env["RUNNER_PERFLOG"] = github.RunnerPerflog
-	env["RUNNER_TRACKING_ID"] = github.RunnerTrackingID
+	if _, ok := common.LookupFold(env, "RUNNER_TRACKING_ID", rc.isEnvCaseInsensitive()); !ok {
+		env["RUNNER_TRACKING_ID"] = github.RunnerTrackingID
+	}
 	env["GITHUB_BASE_REF"] = github.BaseRef
 	env["GITHUB_HEAD_REF"] = github.HeadRef
 	env["GITHUB_SERVER_URL"] = github.ServerURL

act/runner/run_context_test.go

@@ -19,6 +19,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"slices"
+	"strconv"
 	"strings"
 	"sync"
 	"testing"
@@ -1082,6 +1083,51 @@ func TestRunContextGetEnv(t *testing.T) {
 	}
 }
 
+func TestRunContextEnvCaseSensitivity(t *testing.T) {
+	for _, caseInsensitive := range []bool{false, true} {
+		t.Run(strconv.FormatBool(caseInsensitive), func(t *testing.T) {
+			rc := createIfTestRunContext(map[string]*model.Job{
+				"job1": createJob(t, "runs-on: self-hosted\nenv:\n  build_mode: job\n  config_value: job", ""),
+			})
+			rc.Run.Workflow.Env = map[string]string{"BUILD_MODE": "workflow", "CONFIG_VALUE": "workflow", "PATH": "workflow-path", "runner_tool_cache": "workflow-cache"}
+			rc.Config.Env = map[string]string{"CONFIG_VALUE": "config", "RUNNER_TOOL_CACHE": "configured-cache"}
+			rc.Config.DisableActEnv, rc.Config.NoSkipCheckout = true, true
+			rc.Env = nil
+			rc.GetEnv()
+			rc.JobContainer = fakeContainer{ExecutionsEnvironment: &container.HostEnvironment{}, caseInsensitive: caseInsensitive}
+			require.NoError(t, rc.resolvePlatformImage(t.Context()))
+			if caseInsensitive {
+				assert.Equal(t, map[string]string{"build_mode": "job", "CONFIG_VALUE": "config", "PATH": "workflow-path", "RUNNER_TOOL_CACHE": "configured-cache"}, rc.GetEnv())
+			} else {
+				assert.Equal(t, map[string]string{
+					"BUILD_MODE": "workflow", "build_mode": "job", "CONFIG_VALUE": "config",
+					"config_value": "job", "PATH": "workflow-path", "runner_tool_cache": "workflow-cache", "RUNNER_TOOL_CACHE": "configured-cache",
+				}, rc.GetEnv())
+			}
+			want := maps.Clone(rc.GetEnv())
+			rc.Run.Workflow.Env = nil
+			require.NoError(t, rc.Run.Workflow.RawEnv.Encode(`${{ fromJSON('{"BUILD_MODE":"workflow","CONFIG_VALUE":"workflow","PATH":"workflow-path","runner_tool_cache":"workflow-cache"}') }}`))
+			rc.Env = nil
+			evaluated, err := evaluateJobEnv(t.Context(), rc)
+			require.NoError(t, err)
+			assert.Equal(t, want, evaluated)
+			rc.Env = evaluated
+
+			rc.importHostEnv([]string{"Path=host-path", "HOST_ONLY=value", "RUNNER_TRACKING_ID=parent", "runner_tracking_id=parent-lower"})
+			assert.NotContains(t, rc.Env, "RUNNER_TRACKING_ID")
+			assert.Equal(t, "workflow-path", rc.Env["PATH"])
+			assert.Equal(t, "value", rc.Env["HOST_ONLY"])
+			if caseInsensitive {
+				assert.NotContains(t, rc.Env, "Path")
+				assert.NotContains(t, rc.Env, "runner_tracking_id")
+			} else {
+				assert.Equal(t, "host-path", rc.Env["Path"])
+				assert.Equal(t, "parent-lower", rc.Env["runner_tracking_id"])
+			}
+		})
+	}
+}
+
 func TestSetActionEnvRefreshesInputs(t *testing.T) {
 	rc := &RunContext{}
 	rc.setActionEnv(map[string]string{"INPUT_MSG": "pre"})
@@ -1405,13 +1451,14 @@ func TestGetJobContextReportsContainers(t *testing.T) {
 }
 
 func TestCaptureJobContainerInfoExportsDockerWorkspace(t *testing.T) {
+	workdir := t.TempDir()
 	job := &containerMock{}
 	job.On("Inspect", mock.Anything).Return(&container.Info{
 		ID:     "job-container-id",
-		Mounts: map[string]string{"/workspace": "/var/lib/docker/volumes/job/_data"},
+		Mounts: map[string]string{job.ToContainerPath(workdir): "/var/lib/docker/volumes/job/_data"},
 	}, nil)
 	rc := &RunContext{
-		Config:       &Config{Workdir: "/workspace/owner/repo/"},
+		Config:       &Config{Workdir: filepath.Join(workdir, "owner", "repo") + string(filepath.Separator)},
 		Env:          map[string]string{},
 		JobContainer: job,
 	}
@@ -1421,7 +1468,7 @@ func TestCaptureJobContainerInfoExportsDockerWorkspace(t *testing.T) {
 	assert.Equal(t, "job-container-id", rc.jobContainerID)
 	assert.Equal(t, "/var/lib/docker/volumes/job/_data/owner/repo", rc.Env["GITEA_DOCKER_WORKSPACE"])
 
-	rc.Config.Workdir = "/elsewhere"
+	rc.Config.Workdir = filepath.Dir(workdir)
 	rc.Env = map[string]string{}
 	require.NoError(t, rc.captureJobContainerInfo()(t.Context()))
 	assert.NotContains(t, rc.Env, "GITEA_DOCKER_WORKSPACE")

act/runner/runner_windows_test.go

@@ -0,0 +1,43 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package runner
+
+import (
+	"strings"
+	"testing"
+
+	"gitea.com/gitea/runner/act/common/logging"
+	"gitea.com/gitea/runner/act/common/logging/logtest"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestRunEventHostEnvironmentUTF8(t *testing.T) {
+	handler := logtest.New()
+	t.Cleanup(func() {
+		if t.Failed() {
+			for _, record := range handler.AllRecords() {
+				stepIDs, _ := record.Attr("stepID")
+				t.Logf("stepID=%v: %s", stepIDs, record.Message)
+			}
+		}
+	})
+	table := TestJobFileInfo{
+		workdir:      workdir,
+		workflowPath: "windows-utf8",
+		eventName:    "push",
+		platforms:    map[string]string{"windows-latest": "-self-hosted"},
+	}
+	table.runTest(WithJobLoggerFactory(t.Context(), factoryFunc(func() logging.Handler { return handler })), t, &Config{Env: testCheckoutEnv()})
+	var outputSteps []string
+	for _, record := range handler.AllRecords() {
+		if strings.TrimRight(record.Message, "\r\n") == "你好，世界" {
+			stepIDs, ok := record.Attr("stepID")
+			require.True(t, ok)
+			outputSteps = append(outputSteps, stepIDs.([]string)...)
+		}
+	}
+	assert.Equal(t, []string{"cmd", "pwsh", "powershell"}, outputSteps)
+}

act/runner/step.go

@@ -69,10 +69,15 @@ func (s stepStage) String() string {
 }
 
 func processRunnerEnvFileCommand(ctx context.Context, fileName string, rc *RunContext, setter func(context.Context, map[string]string, string)) error {
+	if rc.JobContainer.IsEnvironmentCaseInsensitive() {
+		return container.ParseEnvFile(rc.JobContainer, container.JoinPath(rc.JobContainer.GetActPath(), fileName), func(name, value string) {
+			setter(ctx, map[string]string{"name": name}, value)
+		}, true)(ctx)
+	}
 	env := map[string]string{}
-	err := rc.JobContainer.UpdateFromEnv(path.Join(rc.JobContainer.GetActPath(), fileName), &env)(ctx)
-	for k, v := range env {
-		setter(ctx, map[string]string{"name": k}, v)
+	err := rc.JobContainer.UpdateFromEnv(container.JoinPath(rc.JobContainer.GetActPath(), fileName), &env)(ctx)
+	for key, value := range env {
+		setter(ctx, map[string]string{"name": key}, value)
 	}
 	return err
 }
@@ -139,16 +144,16 @@ func runStepExecutor(step step, stage stepStage, executor common.Executor) commo
 		actPath := rc.JobContainer.GetActPath()
 
 		outputFileCommand := path.Join("workflow", "outputcmd.txt")
-		(*step.getEnv())["GITHUB_OUTPUT"] = path.Join(actPath, outputFileCommand)
+		(*step.getEnv())["GITHUB_OUTPUT"] = container.JoinPath(actPath, outputFileCommand)
 
 		stateFileCommand := path.Join("workflow", "statecmd.txt")
-		(*step.getEnv())["GITHUB_STATE"] = path.Join(actPath, stateFileCommand)
+		(*step.getEnv())["GITHUB_STATE"] = container.JoinPath(actPath, stateFileCommand)
 
 		pathFileCommand := path.Join("workflow", "pathcmd.txt")
-		(*step.getEnv())["GITHUB_PATH"] = path.Join(actPath, pathFileCommand)
+		(*step.getEnv())["GITHUB_PATH"] = container.JoinPath(actPath, pathFileCommand)
 
 		envFileCommand := path.Join("workflow", "envs.txt")
-		(*step.getEnv())["GITHUB_ENV"] = path.Join(actPath, envFileCommand)
+		(*step.getEnv())["GITHUB_ENV"] = container.JoinPath(actPath, envFileCommand)
 
 		// Per-step summary file. Composite sub-steps share the outer job step's index
 		// via the Parent chain so all writes from within a composite action accumulate
@@ -156,7 +161,7 @@ func runStepExecutor(step step, stage stepStage, executor common.Executor) commo
 		topRC := rc.topLevelRunContext()
 		stepSummaryIndex := topRC.CurrentStepIndex
 		summaryFileCommand := path.Join("workflow", "step-summary-"+strconv.Itoa(stepSummaryIndex)+".md")
-		(*step.getEnv())["GITHUB_STEP_SUMMARY"] = path.Join(actPath, summaryFileCommand)
+		(*step.getEnv())["GITHUB_STEP_SUMMARY"] = container.JoinPath(actPath, summaryFileCommand)
 		aliasGiteaEnv(*step.getEnv())
 
 		// Reset the per-phase file-command files. GITHUB_STEP_SUMMARY is intentionally
@@ -203,7 +208,7 @@ func runStepExecutor(step step, stage stepStage, executor common.Executor) commo
 			if fileErr := processRunnerEnvFileCommand(fileCommandCtx, outputFileCommand, rc, rc.setOutput); fileErr != nil && err == nil {
 				err = fileErr
 			}
-			if fileErr := rc.UpdateExtraPath(fileCommandCtx, path.Join(actPath, pathFileCommand)); fileErr != nil && err == nil {
+			if fileErr := rc.UpdateExtraPath(fileCommandCtx, container.JoinPath(actPath, pathFileCommand)); fileErr != nil && err == nil {
 				err = fileErr
 			}
 		}
@@ -351,17 +356,14 @@ func mergeIntoMapCaseInsensitive(target map[string]string, maps ...map[string]st
 	for k := range target {
 		foldKeys[strings.ToLower(k)] = k
 	}
-	toKey := func(s string) string {
-		foldKey := strings.ToLower(s)
-		if k, ok := foldKeys[foldKey]; ok {
-			return k
-		}
-		foldKeys[foldKey] = s
-		return s
-	}
 	for _, m := range maps {
-		for k, v := range m {
-			target[toKey(k)] = v
+		for key, value := range m {
+			foldKey := strings.ToLower(key)
+			if previous, ok := foldKeys[foldKey]; ok {
+				delete(target, previous)
+			}
+			foldKeys[foldKey] = key
+			target[key] = value
 		}
 	}
 }

act/runner/step_docker.go

@@ -52,6 +52,9 @@ func (sd *stepDocker) runUsesContainer() common.Executor {
 	step := sd.Step
 
 	return func(ctx context.Context) error {
+		if rc.isWindowsHost() {
+			return errWindowsHostContainer
+		}
 		if rc.kubernetes {
 			return errKubernetesDocker
 		}

act/runner/step_docker_test.go

@@ -159,3 +159,33 @@ func TestStepDockerNewStepContainer(t *testing.T) {
 		})
 	}
 }
+
+func TestWindowsHostContainerActions(t *testing.T) {
+	for _, test := range []struct {
+		name, hostOS string
+		jobContainer container.ExecutionsEnvironment
+		wantError    bool
+	}{
+		{name: "Windows host", hostOS: "windows", jobContainer: &container.HostEnvironment{}, wantError: true},
+		{name: "Linux host", hostOS: "linux", jobContainer: &container.HostEnvironment{}},
+		{name: "macOS host", hostOS: "darwin", jobContainer: &container.HostEnvironment{}},
+		{name: "Windows with Linux job container", hostOS: "windows", jobContainer: &containerMock{}},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			original := hostOS
+			hostOS = test.hostOS
+			t.Cleanup(func() { hostOS = original })
+			rc := &RunContext{JobContainer: test.jobContainer, kubernetes: true}
+			wantError := errKubernetesDocker.Error()
+			if test.wantError {
+				wantError = errWindowsHostContainer.Error()
+			}
+			t.Run("docker step", func(t *testing.T) {
+				require.EqualError(t, (&stepDocker{RunContext: rc}).runUsesContainer()(t.Context()), wantError)
+			})
+			t.Run("container action", func(t *testing.T) {
+				require.EqualError(t, execAsDocker(t.Context(), &stepActionRemote{RunContext: rc}, "action", "", "", false, stepStageMain), wantError)
+			})
+		})
+	}
+}

act/runner/step_run.go

@@ -100,7 +100,7 @@ func printRunActionHeader(ctx context.Context, step *model.Step, action *model.A
 	maps.Copy(inputs, step.With)
 	if action != nil {
 		for name := range action.Inputs {
-			if _, provided := lookupFold(step.With, name, true); !provided {
+			if _, provided := common.LookupFold(step.With, name, true); !provided {
 				inputs[name] = env[inputEnvKey(name)]
 			}
 		}
@@ -292,7 +292,7 @@ func (sr *stepRun) setupShellCommand(ctx context.Context) (name, script string,
 		name += ".sh"
 	case "pwsh", "powershell":
 		name += ".ps1"
-		runPrepend = "$ErrorActionPreference = 'stop'"
+		runPrepend = "$ErrorActionPreference = 'stop'\n$OutputEncoding = [System.Text.UTF8Encoding]::new($false)\ntry { [Console]::OutputEncoding = $OutputEncoding } catch {}"
 		runAppend = "if ((Test-Path -LiteralPath variable:/LASTEXITCODE)) { exit $LASTEXITCODE }"
 	case "cmd":
 		name += ".cmd"
@@ -302,6 +302,12 @@ func (sr *stepRun) setupShellCommand(ctx context.Context) (name, script string,
 	}
 
 	script = fmt.Sprintf("%s\n%s\n%s", runPrepend, script, runAppend)
+	switch shellCommand {
+	case "powershell":
+		script = "\ufeff" + script
+	case "cmd":
+		script = strings.ReplaceAll(strings.ReplaceAll(script, "\r\n", "\n"), "\n", "\r\n")
+	}
 
 	if !strings.Contains(script, "::add-mask::") && !sr.RunContext.Config.InsecureSecrets {
 		logger.Debugf("Wrote command \n%s\n to '%s'", script, name)
@@ -311,7 +317,30 @@ func (sr *stepRun) setupShellCommand(ctx context.Context) (name, script string,
 
 	rc := sr.getRunContext()
 	scriptPath := fmt.Sprintf("%s/%s", rc.JobContainer.GetActPath(), name)
+	if step.Shell == "pwsh" || step.Shell == "powershell" {
+		scriptPath = expressionStringEscape(scriptPath)
+	}
+	if step.Shell == "bash" || step.Shell == "sh" || step.Shell == "python" {
+		if rc.isWindowsHost() {
+			scriptPath = `"` + scriptPath + `"`
+		} else {
+			scriptPath = shellquote.Join(scriptPath)
+		}
+	}
 	sr.cmdline = strings.ReplaceAll(scCmd, `{0}`, scriptPath)
+	if rc.isWindowsHost() {
+		command := strings.TrimSpace(sr.cmdline)
+		if strings.HasPrefix(command, `"`) {
+			executable, _, closed := strings.Cut(command[1:], `"`)
+			if !closed || executable == "" {
+				return "", "", fmt.Errorf("invalid shell option %q: expected a double-quoted executable", step.Shell)
+			}
+			sr.cmd = []string{executable}
+		} else {
+			sr.cmd = strings.Fields(command)[:1]
+		}
+		return name, script, nil
+	}
 	sr.cmd, err = shellquote.Split(sr.cmdline)
 
 	return name, script, err

act/runner/step_run_test.go

@@ -11,6 +11,7 @@ import (
 	"os"
 	"path/filepath"
 	"runtime"
+	"strings"
 	"testing"
 
 	"gitea.com/gitea/runner/act/container"
@@ -80,14 +81,17 @@ func TestStepRun(t *testing.T) {
 }
 
 func TestStepRunShellParity(t *testing.T) {
-	tests := []struct {
+	const powershellScript = "$ErrorActionPreference = 'stop'\n$OutputEncoding = [System.Text.UTF8Encoding]::new($false)\ntry { [Console]::OutputEncoding = $OutputEncoding } catch {}\necho 你好，世界\nif ((Test-Path -LiteralPath variable:/LASTEXITCODE)) { exit $LASTEXITCODE }"
+	for _, test := range []struct {
 		name, run, shell, workingDir string
+		hostOS, wantCmdline          string
 		actPath                      string
 		env                          map[string]string
 		host                         bool
 		probeErr                     error
 		wantExt                      string
 		wantCmd                      []string
+		wantScript                   string
 		wantErr                      string
 	}{
 		{
@@ -105,24 +109,79 @@ func TestStepRunShellParity(t *testing.T) {
 			wantCmd:  []string{"sh", "-e", "/var/run/act/workflow/1.sh"},
 		},
 		{
-			name:    "builtin pwsh",
-			shell:   "pwsh",
-			actPath: "/var/run/act with spaces",
-			wantExt: ".ps1",
-			wantCmd: []string{"pwsh", "-command", ". '/var/run/act with spaces/workflow/1.ps1'"},
+			name:       "builtin pwsh",
+			run:        "echo 你好，世界",
+			shell:      "pwsh",
+			actPath:    "/var/run/act with spaces/O'Brien",
+			wantExt:    ".ps1",
+			wantCmd:    []string{"pwsh", "-command", ". '/var/run/act with spaces/O''Brien/workflow/1.ps1'"},
+			wantScript: powershellScript,
 		},
 		{
-			name:    "builtin powershell",
-			shell:   "powershell",
-			wantExt: ".ps1",
-			wantCmd: []string{"powershell", "-command", ". '/var/run/act/workflow/1.ps1'"},
+			name:       "builtin powershell",
+			actPath:    "/var/run/act/O'Brien",
+			run:        "echo 你好，世界",
+			shell:      "powershell",
+			wantExt:    ".ps1",
+			wantCmd:    []string{"powershell", "-command", ". '/var/run/act/O''Brien/workflow/1.ps1'"},
+			wantScript: "\ufeff" + powershellScript,
 		},
 		{
-			name:    "custom pwsh template",
-			shell:   "pwsh -NoProfile -File {0}",
-			wantExt: ".ps1",
-			wantCmd: []string{"pwsh", "-NoProfile", "-File", "/var/run/act/workflow/1.ps1"},
+			name:       "custom pwsh template",
+			run:        "echo 你好，世界",
+			shell:      "pwsh -NoProfile -File {0}",
+			wantExt:    ".ps1",
+			wantCmd:    []string{"pwsh", "-NoProfile", "-File", "/var/run/act/workflow/1.ps1"},
+			wantScript: powershellScript,
 		},
+		{
+			name:       "builtin cmd reads and emits UTF-8 without a BOM",
+			run:        "echo 你好，世界",
+			shell:      "cmd",
+			wantExt:    ".cmd",
+			wantCmd:    []string{"cmd", "/D", "/E:ON", "/V:OFF", "/S", "/C", "CALL /var/run/act/workflow/1.cmd"},
+			wantScript: "@echo off\r\necho 你好，世界\r\n",
+		},
+		{
+			name:        "Windows custom executable preserves backslashes and raw arguments",
+			shell:       `C:\Python313\python.exe -X 'utf8' "{0}"`,
+			actPath:     `C:\runner\O'Brien`,
+			hostOS:      "windows",
+			wantCmd:     []string{`C:\Python313\python.exe`},
+			wantCmdline: `C:\Python313\python.exe -X 'utf8' "{0}"`,
+		},
+		{
+			name:        "Windows quoted custom executable preserves spaces and backslashes",
+			shell:       `"C:\Program Files\Python313\python.exe" "{0}"`,
+			actPath:     `C:\runner`,
+			hostOS:      "windows",
+			wantCmd:     []string{`C:\Program Files\Python313\python.exe`},
+			wantCmdline: `"C:\Program Files\Python313\python.exe" "{0}"`,
+		},
+		{
+			name:        "Windows PowerShell escapes apostrophes in the raw command line",
+			run:         "echo 你好，世界",
+			shell:       "pwsh",
+			actPath:     `C:\runner\O'Brien`,
+			hostOS:      "windows",
+			wantExt:     ".ps1",
+			wantCmd:     []string{"pwsh"},
+			wantCmdline: `pwsh -command ". '{0}'"`,
+			wantScript:  powershellScript,
+		},
+		{
+			name:    "Windows unclosed executable quote",
+			shell:   `"C:\Program Files\python.exe {0}`,
+			actPath: `C:\runner`,
+			hostOS:  "windows",
+			wantErr: "expected a double-quoted executable",
+		},
+		{name: "linux builtin bash quotes script path", shell: "bash", actPath: `C:/Users/Jane Doe/O'Brien`, wantCmd: []string{"bash", "--noprofile", "--norc", "-e", "-o", "pipefail", `C:/Users/Jane Doe/O'Brien/workflow/1.sh`}},
+		{name: "linux builtin sh quotes script path", shell: "sh", actPath: `C:/Users/Jane Doe/O'Brien`, wantCmd: []string{"sh", "-e", `C:/Users/Jane Doe/O'Brien/workflow/1.sh`}},
+		{name: "linux builtin python quotes script path", shell: "python", actPath: `C:/Users/Jane Doe/O'Brien`, wantExt: ".py", wantCmd: []string{"python", `C:/Users/Jane Doe/O'Brien/workflow/1.py`}},
+		{name: "windows builtin bash quotes script path", shell: "bash", hostOS: "windows", actPath: `C:\Users\Jane Doe\O'Brien`, wantExt: ".sh", wantCmd: []string{"bash"}, wantCmdline: `bash --noprofile --norc -e -o pipefail "{0}"`},
+		{name: "windows builtin sh quotes script path", shell: "sh", hostOS: "windows", actPath: `C:\Users\Jane Doe\O'Brien`, wantExt: ".sh", wantCmd: []string{"sh"}, wantCmdline: `sh -e "{0}"`},
+		{name: "windows builtin python quotes script path", shell: "python", hostOS: "windows", actPath: `C:\Users\Jane Doe\O'Brien`, wantExt: ".py", wantCmd: []string{"python"}, wantCmdline: `python "{0}"`},
 		{
 			name:    "missing placeholder",
 			shell:   "bash -e",
@@ -156,9 +215,7 @@ func TestStepRunShellParity(t *testing.T) {
 			workingDir: "${{ DIR }}",
 			wantErr:    "unable to interpolate the working directory:",
 		},
-	}
-
-	for _, test := range tests {
+	} {
 		t.Run(test.name, func(t *testing.T) {
 			cm := &containerMock{}
 			var jobContainer container.ExecutionsEnvironment = &shellContainerMock{cm}
@@ -189,22 +246,28 @@ func TestStepRunShellParity(t *testing.T) {
 				env:  test.env,
 			}
 
+			original := hostOS
+			hostOS = cmp.Or(test.hostOS, "linux")
+			t.Cleanup(func() { hostOS = original })
 			name, script, err := sr.setupShellCommand(t.Context())
 			if test.wantErr != "" {
 				require.ErrorContains(t, err, test.wantErr)
 				return
 			}
 			require.NoError(t, err)
-			if test.wantExt == "" {
+			if test.wantExt == "" && test.hostOS != "windows" {
 				test.wantExt = ".sh"
 			}
-			wantScript := "\necho hi\n"
-			if test.wantExt == ".ps1" {
-				wantScript = "$ErrorActionPreference = 'stop'\necho hi\nif ((Test-Path -LiteralPath variable:/LASTEXITCODE)) { exit $LASTEXITCODE }"
-			}
 			assert.Equal(t, "workflow/1"+test.wantExt, name)
-			assert.Equal(t, wantScript, script)
+			assert.Equal(t, cmp.Or(test.wantScript, "\necho hi\n"), script)
 			assert.Equal(t, test.wantCmd, sr.cmd)
+			if test.wantCmdline != "" {
+				scriptPath := jobContainer.GetActPath() + "/workflow/1" + test.wantExt
+				if test.shell == "pwsh" || test.shell == "powershell" {
+					scriptPath = strings.ReplaceAll(scriptPath, "'", "''")
+				}
+				assert.Equal(t, strings.ReplaceAll(test.wantCmdline, "{0}", scriptPath), sr.cmdline)
+			}
 			assert.Equal(t, test.env["DIR"], sr.WorkingDirectory)
 			cm.AssertExpectations(t)
 		})

act/runner/step_test.go

@@ -188,8 +188,9 @@ func TestSetupEnv(t *testing.T) {
 		"RC_KEY":                   "rcvalue",
 		"RUNNER_ENVIRONMENT":       "self-hosted",
 		"RUNNER_PERFLOG":           "/dev/null",
-		"RUNNER_TRACKING_ID":       "",
+		"RUNNER_TRACKING_ID":       env["RUNNER_TRACKING_ID"],
 	}
+	assert.Regexp(t, `^gitea_[A-Z2-7]{26}$`, env["RUNNER_TRACKING_ID"])
 	for name, value := range expected {
 		if suffix, ok := strings.CutPrefix(name, "GITHUB_"); ok {
 			expected["GITEA_"+suffix] = value
@@ -197,6 +198,14 @@ func TestSetupEnv(t *testing.T) {
 	}
 	assert.Equal(t, expected, env)
 
+	t.Run("keeps an inherited RUNNER_TRACKING_ID opt-out", func(t *testing.T) {
+		rc.Env["RUNNER_TRACKING_ID"] = ""
+		optedOut := map[string]string{}
+		require.NoError(t, setupEnv(t.Context(), &stepRun{RunContext: rc, Step: step, env: optedOut}))
+		assert.Contains(t, optedOut, "RUNNER_TRACKING_ID")
+		assert.Empty(t, optedOut["RUNNER_TRACKING_ID"])
+	})
+
 	for _, expression := range []string{"inputs.args", "env.ARGS"} {
 		t.Run("deferred inputs from "+expression, func(t *testing.T) {
 			workflow, err := model.ReadWorkflow(strings.NewReader(`
@@ -410,6 +419,29 @@ func (c *fileCommandTestContainer) GetContainerArchive(ctx context.Context, srcP
 	return c.HostEnvironment.GetContainerArchive(ctx, srcPath)
 }
 
+type windowsFileCommandTestContainer struct {
+	*container.HostEnvironment
+}
+
+func (*windowsFileCommandTestContainer) IsEnvironmentCaseInsensitive() bool { return true }
+
+func TestProcessRunnerEnvFileCommandOrder(t *testing.T) {
+	rc := &RunContext{
+		JobContainer: &windowsFileCommandTestContainer{&container.HostEnvironment{ActPath: t.TempDir()}},
+	}
+	require.NoError(t, os.WriteFile(filepath.Join(rc.JobContainer.GetActPath(), "envs.txt"), []byte("BUILD_MODE=first\nbuild_mode<<EOF\nmiddle\nEOF\nBUILD_MODE=last\n"), 0o600))
+	var entries [][2]string
+	require.NoError(t, processRunnerEnvFileCommand(t.Context(), "envs.txt", rc, func(ctx context.Context, params map[string]string, value string) {
+		entries = append(entries, [2]string{params["name"], value})
+		rc.setEnvFile(ctx, params, value)
+	}))
+	assert.Equal(t, [][2]string{
+		{"BUILD_MODE", "first"}, {"build_mode", "middle"}, {"BUILD_MODE", "last"},
+	}, entries)
+	assert.Equal(t, map[string]string{"BUILD_MODE": "last"}, rc.Env)
+	assert.Equal(t, rc.Env, rc.GlobalEnv)
+}
+
 func TestRunStepExecutorParity(t *testing.T) {
 	newStep := func(t *testing.T, stepModel *model.Step) *stepRun {
 		rc := createRunContext(t)

act/runner/testdata/windows-add-env/push.yml

@@ -18,7 +18,7 @@ jobs:
           echo "Unexpected value for `$env:key: $env:key"
           exit 1
         }
-        if($env:key2 -ne "line1`nline2") {
+        if($env:key2 -ne "line1`r`nline2") {
           echo "Unexpected value for `$env:key2: $env:key2"
           exit 1
         }

act/runner/testdata/windows-utf8/push.yml

@@ -0,0 +1,14 @@
+on: push
+jobs:
+  test:
+    runs-on: windows-latest
+    steps:
+      - id: cmd
+        shell: cmd
+        run: echo 你好，世界
+      - id: pwsh
+        shell: pwsh
+        run: echo '你好，世界'
+      - id: powershell
+        shell: powershell
+        run: echo '你好，世界'

docs/host-mode.md

@@ -0,0 +1,18 @@
+# Host-mode background processes on Windows
+
+Windows host jobs clean up background step processes at job completion. A step can opt out:
+
+```yaml
+steps:
+  - name: Start shared helper
+    env:
+      RUNNER_TRACKING_ID: ""
+    run: Start-Process vendor-helper.exe
+```
+
+- Set the `RUNNER_TRACKING_ID` override in the step's `env` before it starts. Any value different from the job's ID opts out, including an empty string.
+- Opted-out processes and descendants that inherit the override survive normal job cleanup, including workspace process sweeps and expired output waits. Detach helper output because the runner closes leftover output pipes after a bounded wait.
+- Cancelling or timing out an active step still terminates its process tree.
+- The override does not preserve workspace or temporary files. Store persistent helper files outside those directories and arrange the helper's eventual shutdown.
+
+This follows [actions/runner's tracking ID and orphan cleanup](https://github.com/actions/runner/blob/main/src/Runner.Worker/JobExtension.cs). Container jobs follow their container's lifecycle.

internal/app/cmd/cmd.go

@@ -46,7 +46,11 @@ func Execute(ctx context.Context) {
 		Use:   "daemon",
 		Short: "Run as a runner daemon",
 		Args:  cobra.MaximumNArgs(0),
-		RunE:  runDaemon(ctx, &daemArgs, &configFile),
+		RunE: func(command *cobra.Command, args []string) error {
+			return runService(ctx, func(ctx context.Context) error {
+				return runDaemon(ctx, &daemArgs, &configFile)(command, args)
+			})
+		},
 	}
 	daemonCmd.Flags().BoolVar(&daemArgs.Once, "once", false, "Run one job then exit")
 	daemonCmd.Flags().StringVar(&daemArgs.Labels, "labels", os.Getenv("GITEA_RUNNER_LABELS"), "Runner labels, comma separated. Overrides the labels of an already registered runner")

internal/app/cmd/config_test.go

@@ -7,6 +7,7 @@ import (
 	"bytes"
 	"os"
 	"path/filepath"
+	"strconv"
 	"testing"
 
 	"gitea.com/gitea/runner/internal/pkg/config"
@@ -38,7 +39,7 @@ func TestConfigCmdInitWritesTheMinimalConfig(t *testing.T) {
 
 	out, _, err := runConfigCmd(t, file, "init")
 	require.NoError(t, err)
-	assert.Contains(t, out, file)
+	assert.Equal(t, "wrote config file "+strconv.Quote(file)+"\n", out)
 	content, err := os.ReadFile(file)
 	require.NoError(t, err)
 	assert.Equal(t, config.Minimal, string(content))

internal/app/cmd/daemon_test.go

@@ -145,7 +145,7 @@ func TestDaemonRetriesDeclareOutagesAndRemovesOnlyConsumedEphemeralRegistration(
 		{"ephemeral stopped during declare outage", true, true, connect.NewError(connect.CodeUnavailable, "bad gateway"), nil, false},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
-			ctx, cancel := context.WithTimeout(t.Context(), 5*time.Second)
+			ctx, cancel := context.WithCancel(t.Context())
 			defer cancel()
 			service := &daemonTestService{declareErr: tc.declareErr, fetchErr: tc.fetchErr, beforeTask: tc.beforeTask, cancel: cancel}
 			rpcServer := connect.NewServer()

internal/app/cmd/register_test.go

@@ -183,6 +183,9 @@ func TestRegisterInputsAssignToNext(t *testing.T) {
 
 func TestInitInputs(t *testing.T) {
 	t.Setenv(registerTokenEnvVar, "")
+	missingTokenFile := filepath.Join(t.TempDir(), "missing-token")
+	_, readErr := os.ReadFile(missingTokenFile)
+	require.ErrorIs(t, readErr, os.ErrNotExist)
 	for _, tc := range []struct {
 		name, tokenFile, wantErr string
 		env                      *string
@@ -190,8 +193,8 @@ func TestInitInputs(t *testing.T) {
 		{name: "missing token", wantErr: "missing token, token-file argument, or GITEA_RUNNER_REGISTRATION_TOKEN environment variable"},
 		{name: "empty token", env: new(""), wantErr: "missing token, token-file argument, or GITEA_RUNNER_REGISTRATION_TOKEN environment variable"},
 		{
-			name: "invalid token file", tokenFile: "/tmp/nonexistent", env: new("from-env"),
-			wantErr: "cannot read the token file: /tmp/nonexistent, open /tmp/nonexistent: no such file or directory",
+			name: "invalid token file", tokenFile: missingTokenFile, env: new("from-env"),
+			wantErr: "cannot read the token file: " + missingTokenFile + ", " + readErr.Error(),
 		},
 	} {
 		t.Run(tc.name, func(t *testing.T) {

internal/app/cmd/service_others.go

@@ -0,0 +1,12 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+//go:build !windows
+
+package cmd
+
+import "context"
+
+func runService(ctx context.Context, run func(context.Context) error) error {
+	return run(ctx)
+}

internal/app/cmd/service_windows.go

@@ -0,0 +1,107 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package cmd
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+
+	"gitea.com/gitea/runner/act/common/logging"
+
+	"golang.org/x/sys/windows/svc"
+)
+
+func runService(ctx context.Context, run func(context.Context) error) error {
+	isService, err := svc.IsWindowsService()
+	if err != nil {
+		return fmt.Errorf("detect Windows service: %w", err)
+	}
+	if !isService {
+		return run(ctx)
+	}
+
+	handler := &daemonService{ctx: ctx, run: func(ctx context.Context) error {
+		executable, err := os.Executable()
+		if err != nil {
+			return err
+		}
+		if err := os.Chdir(filepath.Dir(executable)); err != nil {
+			return err
+		}
+		logFile, err := os.OpenFile("gitea-runner.log", os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0o600)
+		if err != nil {
+			return fmt.Errorf("open service log: %w", err)
+		}
+		defer func() { _ = logFile.Close() }()
+		previousOutput := logging.Output()
+		logging.SetOutput(logFile)
+		defer logging.SetOutput(previousOutput)
+		err = run(ctx)
+		if errors.Is(err, context.Canceled) && ctx.Err() != nil {
+			return nil
+		}
+		if err != nil {
+			logging.WithError(err).Error("runner daemon failed")
+		}
+		return err
+	}}
+	if err := svc.Run("", handler); err != nil { // SCM supplies the name for an own-process service.
+		return fmt.Errorf("run Windows service: %w", err)
+	}
+	return handler.err
+}
+
+type daemonService struct {
+	ctx context.Context
+	run func(context.Context) error
+	err error
+}
+
+func (s *daemonService) Execute(_args []string, requests <-chan svc.ChangeRequest, changes chan<- svc.Status) (bool, uint32) {
+	ticker := time.NewTicker(time.Second)
+	defer ticker.Stop()
+	return s.execute(requests, changes, ticker.C)
+}
+
+func (s *daemonService) execute(requests <-chan svc.ChangeRequest, changes chan<- svc.Status, ticks <-chan time.Time) (bool, uint32) {
+	changes <- svc.Status{State: svc.StartPending}
+	ctx, cancel := context.WithCancel(s.ctx)
+	defer cancel()
+	done := make(chan error, 1)
+	go func() { done <- s.run(ctx) }()
+	status := svc.Status{State: svc.Running, Accepts: svc.AcceptStop | svc.AcceptShutdown | svc.AcceptPreShutdown}
+	changes <- status
+	for {
+		select {
+		case s.err = <-done:
+			if status.State != svc.StopPending {
+				changes <- svc.Status{State: svc.StopPending}
+			}
+			if s.err != nil {
+				return true, 1
+			}
+			return false, 0
+		case <-ticks:
+			if status.State == svc.StopPending {
+				status.CheckPoint++
+				changes <- status
+			}
+		case request := <-requests:
+			switch request.Cmd {
+			case svc.Interrogate:
+				changes <- status
+			case svc.Stop, svc.Shutdown, svc.PreShutdown:
+				if status.State != svc.StopPending {
+					status = svc.Status{State: svc.StopPending, CheckPoint: 1, WaitHint: 10000}
+					changes <- status
+					cancel()
+				}
+			}
+		}
+	}
+}

internal/app/cmd/service_windows_test.go

@@ -0,0 +1,216 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package cmd
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"gitea.com/gitea/runner/act/common/logging"
+	"gitea.com/gitea/runner/internal/pkg/config"
+
+	"github.com/stretchr/testify/require"
+	"golang.org/x/sys/windows"
+	"golang.org/x/sys/windows/svc"
+	"golang.org/x/sys/windows/svc/mgr"
+)
+
+type serviceExit struct {
+	specific bool
+	code     uint32
+}
+
+func receiveServiceValue[T any](ctx context.Context, t *testing.T, values <-chan T) T {
+	t.Helper()
+	select {
+	case value := <-values:
+		return value
+	case <-ctx.Done():
+		t.Fatal(ctx.Err())
+		var zero T
+		return zero
+	}
+}
+
+func TestDaemonServiceControl(t *testing.T) {
+	for _, command := range []svc.Cmd{svc.Stop, svc.Shutdown, svc.PreShutdown} {
+		t.Run(fmt.Sprint(command), func(t *testing.T) {
+			ctx, cancel := context.WithTimeout(t.Context(), 10*time.Second)
+			defer cancel()
+			release, finish := context.WithCancel(ctx)
+			defer finish()
+			cancelled := make(chan struct{})
+			requests := make(chan svc.ChangeRequest, 1)
+			ticks := make(chan time.Time)
+			changes := make(chan svc.Status, 8)
+			done := make(chan serviceExit, 1)
+			handler := &daemonService{ctx: ctx, run: func(ctx context.Context) error {
+				<-ctx.Done()
+				close(cancelled)
+				<-release.Done()
+				return nil
+			}}
+			go func() {
+				specific, code := handler.execute(requests, changes, ticks)
+				done <- serviceExit{specific, code}
+			}()
+
+			require.Equal(t, svc.Status{State: svc.StartPending}, receiveServiceValue(ctx, t, changes))
+			running := svc.Status{State: svc.Running, Accepts: svc.AcceptStop | svc.AcceptShutdown | svc.AcceptPreShutdown}
+			require.Equal(t, running, receiveServiceValue(ctx, t, changes))
+			requests <- svc.ChangeRequest{Cmd: svc.Interrogate}
+			require.Equal(t, running, receiveServiceValue(ctx, t, changes))
+			requests <- svc.ChangeRequest{Cmd: command}
+			stopping := svc.Status{State: svc.StopPending, CheckPoint: 1, WaitHint: 10000}
+			require.Equal(t, stopping, receiveServiceValue(ctx, t, changes))
+			receiveServiceValue(ctx, t, cancelled)
+			for range 2 {
+				select {
+				case ticks <- time.Time{}:
+				case <-ctx.Done():
+					t.Fatal(ctx.Err())
+				}
+				stopping.CheckPoint++
+				require.Equal(t, stopping, receiveServiceValue(ctx, t, changes))
+			}
+			requests <- svc.ChangeRequest{Cmd: command}
+			requests <- svc.ChangeRequest{Cmd: svc.Interrogate}
+			require.Equal(t, stopping, receiveServiceValue(ctx, t, changes))
+			finish()
+			require.Equal(t, serviceExit{}, receiveServiceValue(ctx, t, done))
+			require.NoError(t, handler.err)
+		})
+	}
+}
+
+func TestDaemonServiceExit(t *testing.T) {
+	for _, daemonErr := range []error{nil, errors.New("daemon failed")} {
+		t.Run(fmt.Sprint(daemonErr), func(t *testing.T) {
+			ctx, cancel := context.WithTimeout(t.Context(), 10*time.Second)
+			defer cancel()
+			changes := make(chan svc.Status, 3)
+			done := make(chan serviceExit, 1)
+			handler := &daemonService{ctx: ctx, run: func(context.Context) error { return daemonErr }}
+			go func() {
+				specific, code := handler.Execute(nil, nil, changes)
+				done <- serviceExit{specific, code}
+			}()
+			require.Equal(t, svc.StartPending, receiveServiceValue(ctx, t, changes).State)
+			require.Equal(t, svc.Running, receiveServiceValue(ctx, t, changes).State)
+			require.Equal(t, svc.Status{State: svc.StopPending}, receiveServiceValue(ctx, t, changes))
+			if daemonErr == nil {
+				require.Equal(t, serviceExit{}, receiveServiceValue(ctx, t, done))
+			} else {
+				require.Equal(t, serviceExit{true, 1}, receiveServiceValue(ctx, t, done))
+			}
+			require.Equal(t, daemonErr, handler.err)
+		})
+	}
+}
+
+func waitForServiceState(t *testing.T, service *mgr.Service, state svc.State) svc.Status {
+	t.Helper()
+	ctx, cancel := context.WithTimeout(context.WithoutCancel(t.Context()), 20*time.Second)
+	defer cancel()
+	ticker := time.NewTicker(10 * time.Millisecond)
+	defer ticker.Stop()
+	for {
+		status, err := service.Query()
+		require.NoError(t, err)
+		if status.State == state {
+			return status
+		}
+		if state == svc.Running && status.State == svc.Stopped {
+			t.Fatalf("service stopped before running: %+v", status)
+		}
+		select {
+		case <-ticker.C:
+		case <-ctx.Done():
+			t.Fatalf("waiting for service state %d, last status: %+v", state, status)
+		}
+	}
+}
+
+func TestWindowsService(t *testing.T) {
+	isService, err := svc.IsWindowsService()
+	require.NoError(t, err)
+	if isService {
+		require.NoError(t, runService(t.Context(), func(ctx context.Context) error {
+			initLogging(&config.Config{})
+			logging.Info("service started")
+			<-ctx.Done()
+			logging.Info("service stopped")
+			return nil
+		}))
+		return
+	}
+	if !windows.GetCurrentProcessToken().IsElevated() {
+		t.Skip("Windows service test requires elevation")
+	}
+
+	executable, err := os.Executable()
+	require.NoError(t, err)
+	binary, err := os.ReadFile(executable)
+	require.NoError(t, err)
+	directory := t.TempDir()
+	serviceExecutable := filepath.Join(directory, "runner service.test.exe")
+	require.NoError(t, os.WriteFile(serviceExecutable, binary, 0o600))
+	manager, err := mgr.Connect()
+	require.NoError(t, err)
+	t.Cleanup(func() { require.NoError(t, manager.Disconnect()) })
+	service, err := manager.CreateService(
+		fmt.Sprintf("gitea-runner-test-%d-%d", os.Getpid(), time.Now().UnixNano()),
+		serviceExecutable, mgr.Config{StartType: mgr.StartManual}, "-test.run=^TestWindowsService$", "-test.timeout=1m",
+	)
+	require.NoError(t, err)
+	t.Cleanup(func() { require.NoError(t, service.Close()) })
+	t.Cleanup(func() { require.NoError(t, service.Delete()) })
+	var process windows.Handle
+	t.Cleanup(func() {
+		if process != 0 {
+			require.NoError(t, windows.CloseHandle(process))
+		}
+	})
+	t.Cleanup(func() {
+		if process == 0 {
+			return
+		}
+		result, err := windows.WaitForSingleObject(process, 20000)
+		require.NoError(t, err)
+		if result == uint32(windows.WAIT_TIMEOUT) {
+			t.Error("service process did not exit after stopping")
+			require.NoError(t, windows.TerminateProcess(process, 1))
+			result, err = windows.WaitForSingleObject(process, 20000)
+			require.NoError(t, err)
+		}
+		require.Equal(t, uint32(windows.WAIT_OBJECT_0), result)
+	})
+	t.Cleanup(func() {
+		status, err := service.Query()
+		require.NoError(t, err)
+		if status.State != svc.Stopped {
+			_, err := service.Control(svc.Stop)
+			require.NoError(t, err)
+			waitForServiceState(t, service, svc.Stopped)
+		}
+	})
+	require.NoError(t, service.Start())
+	running := waitForServiceState(t, service, svc.Running)
+	process, err = windows.OpenProcess(windows.SYNCHRONIZE|windows.PROCESS_TERMINATE, false, running.ProcessId)
+	require.NoError(t, err)
+	_, err = service.Control(svc.Stop)
+	require.NoError(t, err)
+	stopped := waitForServiceState(t, service, svc.Stopped)
+	require.Zero(t, stopped.Win32ExitCode)
+	require.Zero(t, stopped.ServiceSpecificExitCode)
+	log, err := os.ReadFile(filepath.Join(directory, "gitea-runner.log"))
+	require.NoError(t, err)
+	require.Contains(t, string(log), "service started")
+	require.Contains(t, string(log), "service stopped")
+}

internal/app/run/health_check.go

@@ -59,9 +59,8 @@ func (r *Runner) checkConfiguredHealth(ctx context.Context) (bool, string) {
 func executeHealthCheck(ctx context.Context, script string, timeout time.Duration, env map[string]string) error {
 	checkCtx, cancel := context.WithTimeout(ctx, timeout)
 	defer cancel()
-	cmd := exec.CommandContext(checkCtx, script)
+	cmd := scriptCommand(checkCtx, script)
 	cmd.Env = envListFromMap(env)
-	cmd.SysProcAttr = process.SysProcAttr(script, false)
 	writer := common.NewLineWriter(func(line string) bool {
 		line = strings.TrimRight(line, "\r\n")
 		if line != "" {

internal/app/run/health_check_windows_test.go

@@ -0,0 +1,25 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package run
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestExecuteHealthCheckExeAndBatchPathsWithSpace(t *testing.T) {
+	whoami, err := os.ReadFile(filepath.Join(os.Getenv("SystemRoot"), "System32", "whoami.exe"))
+	require.NoError(t, err)
+	dir := filepath.Join(t.TempDir(), "health check")
+	require.NoError(t, os.MkdirAll(dir, 0o755))
+	require.NoError(t, os.WriteFile(filepath.Join(dir, "probe.exe"), whoami, 0o755))
+	require.NoError(t, os.WriteFile(filepath.Join(dir, "probe.cmd"), []byte("@exit /b 0\r\n"), 0o755))
+	for _, name := range []string{"probe.exe", "probe.cmd"} {
+		require.NoError(t, executeHealthCheck(t.Context(), filepath.Join(dir, name), time.Minute, nil))
+	}
+}

internal/app/run/post_task_script.go

@@ -8,6 +8,8 @@ import (
 	"errors"
 	"io"
 	"os/exec"
+	"path/filepath"
+	"runtime"
 	"strconv"
 	"strings"
 	"time"
@@ -39,9 +41,8 @@ func (r *Runner) runPostTaskScript(ctx context.Context, reporter *report.Reporte
 	env := r.postTaskScriptEnv(reporter, task, workdir)
 	logging.Infof("running post-task script %q for task %d", script, task.Id)
 
-	cmd := exec.CommandContext(scriptCtx, script)
+	cmd := scriptCommand(scriptCtx, script)
 	cmd.Env = envListFromMap(env)
-	cmd.SysProcAttr = process.SysProcAttr(script, false)
 
 	stdout := postTaskScriptLogWriter("stdout")
 	stderr := postTaskScriptLogWriter("stderr")
@@ -75,6 +76,17 @@ func (r *Runner) runPostTaskScript(ctx context.Context, reporter *report.Reporte
 	}
 }
 
+func scriptCommand(ctx context.Context, script string) *exec.Cmd { // Windows batch files need cmd.exe, CreateProcess cannot start them
+	if ext := strings.ToLower(filepath.Ext(script)); runtime.GOOS == "windows" && (ext == ".bat" || ext == ".cmd") {
+		cmd := exec.CommandContext(ctx, "cmd.exe")
+		cmd.SysProcAttr = process.SysProcAttr(`cmd.exe /d /s /c ""`+script+`""`, false)
+		return cmd
+	}
+	cmd := exec.CommandContext(ctx, script)
+	cmd.SysProcAttr = process.SysProcAttr("", false)
+	return cmd
+}
+
 func postTaskScriptContext(ctx context.Context, timeout time.Duration) (context.Context, context.CancelFunc) {
 	// Detach from the task context's deadline and cancellation: the task has
 	// already finished by the time the post-task script runs, so the script must

internal/app/run/post_task_script_test.go

@@ -7,10 +7,12 @@ import (
 	"context"
 	"os"
 	"path/filepath"
+	"runtime"
 	"testing"
 	"time"
 
 	"gitea.com/gitea/runner/act/common/logging"
+	"gitea.com/gitea/runner/act/common/logging/logtest"
 	"gitea.com/gitea/runner/internal/pkg/config"
 	"gitea.com/gitea/runner/internal/pkg/metrics"
 	"gitea.com/gitea/runner/internal/pkg/report"
@@ -39,9 +41,15 @@ func TestRunPostTaskScriptSkippedWhenEmpty(t *testing.T) {
 }
 
 func TestRunPostTaskScriptNonZeroExitDoesNotPanic(t *testing.T) {
+	hook := logtest.SetDefault(t)
 	dir := t.TempDir()
 	scriptPath := filepath.Join(dir, "fail.sh")
-	require.NoError(t, os.WriteFile(scriptPath, []byte("#!/bin/sh\nexit 2\n"), 0o700))
+	script := "#!/bin/sh\nexit 2\n"
+	if runtime.GOOS == "windows" {
+		scriptPath = filepath.Join(dir, "fail.cmd")
+		script = "@exit /b 2\r\n"
+	}
+	require.NoError(t, os.WriteFile(scriptPath, []byte(script), 0o700))
 
 	cfg, err := config.LoadDefault("")
 	require.NoError(t, err)
@@ -59,6 +67,8 @@ func TestRunPostTaskScriptNonZeroExitDoesNotPanic(t *testing.T) {
 	require.NotPanics(t, func() {
 		r.runPostTaskScript(ctx, reporter, task, "/workspace/owner/repo")
 	})
+	require.NotNil(t, hook.LastRecord())
+	assert.Contains(t, hook.LastRecord().Message, "exited with code 2")
 }
 
 func TestPostTaskScriptContextUsesFullTimeout(t *testing.T) {
@@ -113,10 +123,15 @@ func TestPostTaskScriptEnv(t *testing.T) {
 }
 
 func TestRunPostTaskScriptIntegration(t *testing.T) {
-	dir := t.TempDir()
+	dir := filepath.Join(t.TempDir(), "script directory")
+	require.NoError(t, os.Mkdir(dir, 0o700))
 	outFile := filepath.Join(dir, "out.txt")
 	scriptPath := filepath.Join(dir, "post-task.sh")
 	script := "#!/bin/sh\nprintf '%s %s %s' \"$GITEA_TASK_ID\" \"$GITEA_JOB_RESULT\" \"$CUSTOM\" > \"" + outFile + "\"\n"
+	if runtime.GOOS == "windows" {
+		scriptPath = filepath.Join(dir, "post-task.cmd")
+		script = "@echo off\r\n<nul set /p \"=%GITEA_TASK_ID% %GITEA_JOB_RESULT% %CUSTOM%\" > \"" + outFile + "\"\r\nexit /b 0\r\n"
+	}
 	require.NoError(t, os.WriteFile(scriptPath, []byte(script), 0o700))
 
 	cfg, err := config.LoadDefault("")

internal/app/run/runner.go

@@ -168,7 +168,7 @@ func (r *Runner) OnIdle(ctx context.Context) {
 	}
 	// Bind-workdir mode: reclaim stale per-task workspace dirs (numeric task IDs).
 	if r.cfg.Container.BindWorkdir {
-		r.cleanupStaleDirs(ctx, filepath.FromSlash("/"+strings.TrimLeft(r.cfg.Container.WorkdirParent, "/")), isTaskIDDir)
+		r.cleanupStaleDirs(ctx, containerWorkdirRoot(r.cfg.Container.WorkdirParent), isTaskIDDir)
 	}
 	// Host mode: reclaim per-job scratch dirs left behind when HostEnvironment
 	// cleanup timed out (e.g. a delete stalled by an AV/EDR filter driver). They
@@ -557,12 +557,12 @@ func (r *Runner) run(ctx context.Context, task *runnerv1.Task, reporter *report.
 		actionCloneDepth = 0
 	}
 
-	workdirParent := strings.TrimLeft(r.cfg.Container.WorkdirParent, "/")
+	workdirParent := containerWorkdirRoot(r.cfg.Container.WorkdirParent)
 	if r.cfg.Container.BindWorkdir {
 		// Append the task ID to isolate concurrent jobs from the same repo.
-		workdirParent = fmt.Sprintf("%s/%d", workdirParent, task.Id)
+		workdirParent = filepath.Join(workdirParent, strconv.FormatInt(task.Id, 10))
 	}
-	workdir := filepath.FromSlash(fmt.Sprintf("/%s/%s", workdirParent, preset.Repository))
+	workdir := filepath.Join(workdirParent, filepath.FromSlash(preset.Repository))
 	if runtime.GOOS == "windows" {
 		if abs, err := filepath.Abs(workdir); err == nil {
 			workdir = abs
@@ -648,10 +648,8 @@ func (r *Runner) run(ctx context.Context, task *runnerv1.Task, reporter *report.
 	reporter.SetOutputs(job.Outputs)
 
 	if r.cfg.Container.BindWorkdir {
-		// Remove the entire task-specific directory (e.g. /workspace/<task_id>).
-		taskDir := filepath.FromSlash("/" + workdirParent)
-		if err := os.RemoveAll(taskDir); err != nil {
-			logging.Warnf("failed to clean up workspace %s: %v", taskDir, err)
+		if err := os.RemoveAll(workdirParent); err != nil {
+			logging.Warnf("failed to clean up workspace %s: %v", workdirParent, err)
 		}
 	}
 
@@ -821,7 +819,7 @@ func (r *Runner) setHealthStatus(ready bool, reason string) {
 func checkFreeDisk(cfg *config.Config) (bool, string) {
 	root := cfg.Host.WorkdirParent
 	if cfg.Container.BindWorkdir {
-		root = filepath.FromSlash("/" + strings.TrimLeft(cfg.Container.WorkdirParent, "/"))
+		root = containerWorkdirRoot(cfg.Container.WorkdirParent)
 	}
 	root = nearestExistingPath(root)
 	available, err := disk.FreeBytes(root)
@@ -835,6 +833,13 @@ func checkFreeDisk(cfg *config.Config) (bool, string) {
 	return true, "ok"
 }
 
+func containerWorkdirRoot(parent string) string {
+	if filepath.IsAbs(parent) {
+		return filepath.Clean(parent)
+	}
+	return filepath.Join(string(filepath.Separator), parent)
+}
+
 func nearestExistingPath(path string) string {
 	for path != "" {
 		if _, err := os.Stat(path); err == nil {

internal/app/run/runner_idle_cleanup_test.go

@@ -241,9 +241,6 @@ func TestRunnerShouldRunIdleCleanupSkipsWhenDisabled(t *testing.T) {
 	})
 }
 
-// TestRunnerOnIdleIntegratesCleanup wires the full OnIdle entry point and
-// confirms it walks workdir_parent (after the leading-slash trim that
-// matches the production path construction) and removes stale numeric dirs.
 func TestRunnerOnIdleIntegratesCleanup(t *testing.T) {
 	now := time.Date(2026, time.April, 29, 20, 0, 0, 0, time.UTC)
 	root := t.TempDir()
@@ -255,7 +252,7 @@ func TestRunnerOnIdleIntegratesCleanup(t *testing.T) {
 		cfg: &config.Config{
 			Container: config.Container{
 				BindWorkdir:   true,
-				WorkdirParent: root, // leading slash absent, OnIdle reattaches it
+				WorkdirParent: root,
 			},
 			Runner: config.Runner{
 				WorkdirCleanupAge:   24 * time.Hour,
@@ -371,3 +368,16 @@ func TestRunnerOnIdleRemovesOrphanNetworks(t *testing.T) {
 	assert.Equal(t, []string{"a1b2c3d4e5f6", ""}, detached)
 	assert.Equal(t, []string{"runner-1"}, sweptPods)
 }
+
+func TestContainerWorkdirRoot(t *testing.T) {
+	absolute := t.TempDir()
+	rooted := filepath.Join(string(filepath.Separator), "workspace")
+	for input, want := range map[string]string{
+		"workspace":          rooted,
+		"/workspace/":        rooted,
+		absolute:             absolute,
+		absolute + "/nested": filepath.Join(absolute, "nested"),
+	} {
+		assert.Equal(t, want, containerWorkdirRoot(input), input)
+	}
+}

internal/pkg/action/checkout/checkout.go

@@ -42,7 +42,10 @@ func Main(ctx context.Context, c *action.Context) (err error) {
 			return fmt.Errorf("checkout: unsupported input %q", name)
 		}
 	}
-	dst, err := workspaceDestination(c.Workspace, c.Inputs["path"])
+	runnerContext := c.Container.GetRunnerContext(ctx)
+	executionOS, _ := runnerContext["os"].(string)
+	windows := strings.EqualFold(executionOS, "windows")
+	dst, err := workspaceDestination(c.Workspace, c.Inputs["path"], windows)
 	if err != nil {
 		return err
 	}
@@ -63,8 +66,8 @@ func Main(ctx context.Context, c *action.Context) (err error) {
 				return err
 			}
 		}
-		if output := c.Env["GITHUB_OUTPUT"]; output != "" {
-			return c.Container.Copy(path.Dir(output), &container.FileEntry{Name: path.Base(output), Mode: 0o666, Body: fmt.Sprintf("ref=%s\ncommit=%s\n", ghc.Ref, ghc.Sha)})(ctx)
+		if output := filepath.ToSlash(c.Env["GITHUB_OUTPUT"]); output != "" {
+			return c.Container.Copy(container.JoinPath(output, ".."), &container.FileEntry{Name: path.Base(output), Mode: 0o666, Body: fmt.Sprintf("ref=%s\ncommit=%s\n", ghc.Ref, ghc.Sha)})(ctx)
 		}
 		return nil
 	}
@@ -72,6 +75,7 @@ func Main(ctx context.Context, c *action.Context) (err error) {
 	co := &checkout{
 		url:       strings.TrimSuffix(ghc.ServerURL, "/") + "/" + repository,
 		dst:       dst,
+		windows:   windows,
 		ref:       ref,
 		depth:     depth,
 		fetchTags: boolInput(c.Inputs, "fetch-tags", false),
@@ -114,10 +118,11 @@ func Main(ctx context.Context, c *action.Context) (err error) {
 	}
 
 	// named like actions/checkout's, which create-pull-request knows to hide, and gone with the job
-	runnerTemp, _ := c.Container.GetRunnerContext(ctx)["temp"].(string)
+	runnerTemp, _ := runnerContext["temp"].(string)
+	runnerTemp = filepath.ToSlash(runnerTemp)
 	digest := sha256.Sum256([]byte(dst))
 	credentials := fmt.Sprintf("git-credentials-%x.config", digest[:8])
-	co.credentials = path.Join(runnerTemp, credentials)
+	co.credentials = container.JoinPath(runnerTemp, credentials)
 	persist := boolInput(c.Inputs, "persist-credentials", true)
 	config, remoteConfig := serverConfig(ghc.ServerURL, cmp.Or(c.Inputs["token"], ghc.Token), c.InsecureSkipTLS, co.submodules != "" && sshKey == "")
 	if boolInput(c.Inputs, "set-safe-directory", true) {
@@ -140,22 +145,21 @@ func Main(ctx context.Context, c *action.Context) (err error) {
 		if err := c.Container.Copy(runnerTemp, &container.FileEntry{Name: cert, Mode: 0o600, Body: string(certPEM)}, &container.FileEntry{Name: key, Mode: 0o600, Body: string(keyPEM)})(ctx); err != nil {
 			return err
 		}
-		scope := "http." + strings.TrimSuffix(ghc.ServerURL, "/") + "/."
-		remoteConfig = append(remoteConfig, scope+"sslCert="+path.Join(runnerTemp, cert), scope+"sslKey="+path.Join(runnerTemp, key))
+		remoteConfig = append(remoteConfig, git.ClientCertConfig("http."+strings.TrimSuffix(ghc.ServerURL, "/")+"/.", container.JoinPath(runnerTemp, cert), container.JoinPath(runnerTemp, key), executionOS)...)
 	}
 	env := gitEnv(c, remoteConfig)
 	env["GIT_LFS_SKIP_SMUDGE"] = strconv.FormatBool(!co.lfs || len(co.sparse) == 0) // lfs pull fetches the objects of a full checkout in one go
 	if sshKey != "" {
 		key := fmt.Sprintf("git-ssh-key-%x", digest[:8])
 		files := []*container.FileEntry{{Name: key, Mode: 0o600, Body: sshKey + "\n"}}
-		ssh := []string{"ssh", "-i", path.Join(runnerTemp, key)}
+		ssh := []string{"ssh", "-i", container.JoinPath(runnerTemp, key)}
 		if boolInput(c.Inputs, "ssh-strict", true) {
 			ssh = append(ssh, "-o", "StrictHostKeyChecking=yes", "-o", "CheckHostIP=no")
 		}
 		if knownHosts := strings.TrimSpace(c.Inputs["ssh-known-hosts"]); knownHosts != "" {
 			name := fmt.Sprintf("git-ssh-known-hosts-%x", digest[:8])
 			files = append(files, &container.FileEntry{Name: name, Mode: 0o600, Body: knownHosts + "\n"})
-			ssh = append(ssh, "-o", "UserKnownHostsFile=~/.ssh/known_hosts "+strconv.Quote(path.Join(runnerTemp, name)))
+			ssh = append(ssh, "-o", "UserKnownHostsFile=~/.ssh/known_hosts "+strconv.Quote(container.JoinPath(runnerTemp, name)))
 		}
 		if !persist {
 			defer func() {
@@ -218,7 +222,7 @@ func gitEnv(c *action.Context, config []string) map[string]string {
 	env := map[string]string{"GIT_TERMINAL_PROMPT": "0"}
 	maps.Copy(env, c.Env)
 	maps.DeleteFunc(env, func(name, _ string) bool { return slices.Contains(git.LocalEnvVars, name) })
-	maps.Copy(env, git.ConfigEnv(append([]string{"protocol.version=2", "init.defaultBranch=main", "advice.detachedHead=false", "maintenance.auto=false"}, config...)...))
+	maps.Copy(env, git.ConfigEnv(append([]string{"protocol.version=2", "init.defaultBranch=main", "advice.detachedHead=false", "maintenance.auto=false", "core.longpaths=true"}, config...)...))
 	return env
 }
 
@@ -301,7 +305,7 @@ type checkout struct {
 	filter, submodules                                     string
 	sparse                                                 []string
 	depth                                                  int
-	fetchTags, clean, lfs, progress, cone                  bool
+	fetchTags, clean, lfs, progress, cone, windows         bool
 }
 
 const fullDepth = "2147483647" // git's INFINITE_DEPTH, also deepens a shallow dst
@@ -315,6 +319,9 @@ func (co *checkout) commands() (commands [][]string, fetched int) {
 		repo("config", "remote.origin.fetch", "+refs/heads/*:refs/remotes/origin/*"),
 		repo("config", "--replace-all", "--fixed-value", credentialsInclude, co.credentials, co.credentials),
 	}
+	if co.windows {
+		commands = append(commands, repo("config", "core.longpaths", "true")) // later steps run git on the checkout too
+	}
 	if co.lfs {
 		commands = append(commands, repo("lfs", "install", "--local"))
 	}
@@ -451,9 +458,13 @@ func boolInput(inputs map[string]string, name string, fallback bool) bool {
 	return strings.EqualFold(value, "true") || value == "" && fallback
 }
 
-func workspaceDestination(workspace, checkoutPath string) (string, error) {
-	cleanPath := path.Clean(strings.TrimSpace(checkoutPath))
-	if path.IsAbs(cleanPath) || cleanPath == ".." || strings.HasPrefix(cleanPath, "../") {
+func workspaceDestination(workspace, checkoutPath string, windows bool) (string, error) {
+	cleanPath := strings.TrimSpace(checkoutPath)
+	if windows {
+		cleanPath = strings.ReplaceAll(cleanPath, `\`, "/")
+	}
+	cleanPath = path.Clean(cleanPath)
+	if path.IsAbs(cleanPath) || cleanPath == ".." || strings.HasPrefix(cleanPath, "../") || windows && len(cleanPath) > 1 && cleanPath[1] == ':' {
 		return "", fmt.Errorf("checkout: path %q must be relative to the workspace", checkoutPath)
 	}
 	return path.Join(workspace, cleanPath), nil

internal/pkg/action/checkout/checkout_test.go

@@ -13,9 +13,11 @@ import (
 	"io"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"os"
 	"os/exec"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"testing"
 
@@ -50,6 +52,7 @@ func gitLog(dir string) []string {
 
 func TestCheckout(t *testing.T) {
 	server := t.TempDir()
+	serverURL := (&url.URL{Scheme: "file", Path: "/" + strings.TrimPrefix(filepath.ToSlash(server), "/")}).String()
 	var sha string
 	_, lfsErr := exec.LookPath("git-lfs")
 	require.True(t, t.Run("fixtures", func(t *testing.T) {
@@ -192,13 +195,16 @@ exec sh -c "$(printf '%s' "$last" | sed "s#git-upload-pack '/\(.*\)\.git'#git up
 			if tc.inputs["lfs"] == "true" && lfsErr != nil {
 				t.Skip("needs git-lfs")
 			}
+			if tc.inputs["ssh-key"] != "" && runtime.GOOS == "windows" {
+				t.Skip("Git for Windows puts its own ssh ahead of the fake one on PATH")
+			}
 			workspace, runnerTemp := t.TempDir(), t.TempDir()
 			output := filepath.Join(runnerTemp, "output")
 			checkout := func(inputs map[string]string) error {
 				return Main(t.Context(), &action.Context{
 					Container: &container.HostEnvironment{Path: workspace, TmpDir: runnerTemp, StdOut: io.Discard},
 					Github: &model.GithubContext{
-						Repository: "org/repo", Ref: cmp.Or(tc.eventRef, "refs/heads/main"), Sha: sha, ServerURL: "file://" + server, Token: "tok", Event: tc.event,
+						Repository: "org/repo", Ref: cmp.Or(tc.eventRef, "refs/heads/main"), Sha: sha, ServerURL: serverURL, Token: "tok", Event: tc.event,
 					},
 					Inputs:         inputs,
 					HostWorkdir:    host,
@@ -207,7 +213,7 @@ exec sh -c "$(printf '%s' "$last" | sed "s#git-upload-pack '/\(.*\)\.git'#git up
 					NoSkipCheckout: tc.noSkip,
 					Env: map[string]string{
 						"PATH": tools + string(os.PathListSeparator) + os.Getenv("PATH"), "GIT_CONFIG_GLOBAL": globalConfig, "GIT_CONFIG_NOSYSTEM": "1",
-						"GIT_DIR": host, "GITHUB_OUTPUT": output, "SSH_SERVER": server, "SSH_ARGS": filepath.Join(runnerTemp, "ssh-args"),
+						"GIT_DIR": host, "GITHUB_OUTPUT": output, "SSH_SERVER": filepath.ToSlash(server), "SSH_ARGS": filepath.Join(runnerTemp, "ssh-args"),
 					},
 				})
 			}
@@ -270,7 +276,7 @@ exec sh -c "$(printf '%s' "$last" | sed "s#git-upload-pack '/\(.*\)\.git'#git up
 			for _, repo := range repos {
 				assert.Equal(t, tc.inputs["clean"] == "false", fileExists(filepath.Join(repo, "untracked")), repo)
 				assert.Len(t, strings.Fields(gitOutput(repo, "config", "--local", "--get-all", credentialsInclude)), 1, repo)
-				headers, _ := exec.Command("git", "-C", repo, "config", "--get-all", "http.file://"+server+"/.extraheader").Output()
+				headers, _ := exec.Command("git", "-C", repo, "config", "--get-all", "http."+serverURL+"/.extraheader").Output()
 				assert.Equal(t, persisted, string(headers) == "\nAuthorization: Basic dG9rZW46dG9r\n", repo)
 			}
 			if tc.inputs["ssh-key"] != "" {
@@ -354,3 +360,25 @@ func fileExists(name string) bool {
 	_, err := os.Stat(name)
 	return err == nil
 }
+
+func TestWorkspaceDestination(t *testing.T) {
+	for _, tc := range []struct {
+		path    string
+		windows bool
+		want    string
+	}{
+		{`..\x`, true, ""},
+		{`C:x`, true, ""},
+		{`a\b`, true, "/w/a/b"},
+		{`..\x`, false, `/w/..\x`},
+		{`a:b`, false, "/w/a:b"},
+	} {
+		got, err := workspaceDestination("/w", tc.path, tc.windows)
+		if tc.want == "" {
+			assert.ErrorContains(t, err, "must be relative", tc.path)
+		} else {
+			require.NoError(t, err, tc.path)
+			assert.Equal(t, tc.want, got, tc.path)
+		}
+	}
+}

internal/pkg/config/config.example.yaml

@@ -327,8 +327,8 @@ health_check:
   # Minimum free space required on the filesystem holding runner workspaces.
   # Defaults to 1024 MiB when omitted or set to zero.
   #min_free_disk_space_mb: 1024
-  # Optional additional executable. A non-zero exit, timeout, or startup failure
-  # marks the runner unavailable.
+  # Optional additional executable, or a .bat or .cmd file on Windows. A non-zero
+  # exit, timeout, or startup failure marks the runner unavailable.
   #script: ''
   # How long a script result is cached and its maximum execution time.
   #interval: 30s

internal/pkg/config/config_test.go

@@ -109,7 +109,7 @@ cache:
     endpoint: "http://minio:9000"
     bucket: "caches"
     prefix: "/runners/"
-    access_key_file: "` + accessPath + `"
+    access_key_file: '` + accessPath + `'
     secret_key: "secret"
 `
 	require.NoError(t, os.WriteFile(path, []byte(content), 0o600))
@@ -341,20 +341,20 @@ func TestLoadDefault_ExternalCacheSecret(t *testing.T) {
 		{name: "without secret", yaml: externalCache, wantErr: "external_secret"},
 		{name: "inline secret", yaml: externalCache + "  external_secret: \"shh\"\n"},
 		{
-			name: "from file", yaml: externalCache + "  external_secret_file: \"$DIR/cache.secret\"\n",
+			name: "from file", yaml: externalCache + "  external_secret_file: '$DIR/cache.secret'\n",
 			fileContent: "  s3cr3t\n", wantSecret: "s3cr3t",
 		},
 		{
-			name: "from file when disabled", yaml: "\ncache:\n  enabled: false\n  external_secret_file: \"$DIR/cache.secret\"\n",
+			name: "from file when disabled", yaml: "\ncache:\n  enabled: false\n  external_secret_file: '$DIR/cache.secret'\n",
 			fileContent: "s3cr3t", wantSecret: "s3cr3t",
 		},
 		{
-			name: "inline and file conflict", yaml: externalCache + "  external_secret: \"inline\"\n  external_secret_file: \"$DIR/cache.secret\"\n",
+			name: "inline and file conflict", yaml: externalCache + "  external_secret: \"inline\"\n  external_secret_file: '$DIR/cache.secret'\n",
 			fileContent: "s3cr3t", wantErr: "both set",
 		},
-		{name: "missing file", yaml: externalCache + "  external_secret_file: \"$DIR/absent.secret\"\n", wantErr: "read cache.external_secret_file"},
+		{name: "missing file", yaml: externalCache + "  external_secret_file: '$DIR/absent.secret'\n", wantErr: "read cache.external_secret_file"},
 		{
-			name: "empty file", yaml: externalCache + "  external_secret_file: \"$DIR/cache.secret\"\n",
+			name: "empty file", yaml: externalCache + "  external_secret_file: '$DIR/cache.secret'\n",
 			fileContent: "\n  \n", wantErr: "contains no secret",
 		},
 	} {

internal/pkg/process/console_others.go

@@ -0,0 +1,8 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+//go:build !windows
+
+package process
+
+func UTF8Console() {}

internal/pkg/process/console_windows.go

@@ -0,0 +1,11 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package process
+
+import "golang.org/x/sys/windows"
+
+func UTF8Console() { // per step, as GitHub's runner runs chcp 65001 before its steps
+	_ = windows.SetConsoleCP(65001)
+	_ = windows.SetConsoleOutputCP(65001)
+}

internal/pkg/process/group_windows.go

@@ -11,9 +11,7 @@ import (
 	"golang.org/x/sys/windows"
 )
 
-// Group is a job-scoped Windows Job Object holding every process the job's steps
-// start; closing it terminates whatever is still assigned, reaching orphans the
-// per-step Killer misses (a completed step's leftover has no parent to walk from).
+// Group holds tracked step processes in a job-scoped Windows Job Object.
 type Group struct {
 	mu  sync.Mutex
 	job windows.Handle

internal/pkg/process/group_windows_test.go

@@ -4,69 +4,25 @@
 package process
 
 import (
-	"fmt"
-	"os"
 	"os/exec"
-	"path/filepath"
-	"strconv"
-	"strings"
 	"testing"
 	"time"
 
 	"github.com/stretchr/testify/require"
 )
 
-// startOrphanMaker starts a process that spawns a detached, long-lived child and
-// exits, leaving the child parentless. Returns the cmd and the child's PID file.
-func startOrphanMaker(t *testing.T) (*exec.Cmd, string) {
-	t.Helper()
-
-	pidFile := filepath.Join(t.TempDir(), "child.pid")
-	script := fmt.Sprintf(
-		`$c = Start-Process powershell -PassThru -ArgumentList '-NoProfile','-Command','Start-Sleep -Seconds 600'; `+
-			`Set-Content -LiteralPath %q -Value $c.Id`, pidFile)
-
-	cmd := exec.Command("powershell.exe", "-NoProfile", "-Command", script)
-	require.NoError(t, cmd.Start())
-	t.Cleanup(func() { _ = cmd.Process.Kill() })
-
-	return cmd, pidFile
-}
-
-// awaitChildPID waits until the spawned child has reported its PID and is running.
-func awaitChildPID(t *testing.T, pidFile string) int {
-	t.Helper()
-
-	var childPID int
-	require.Eventually(t, func() bool {
-		b, err := os.ReadFile(pidFile)
-		if err != nil {
-			return false
-		}
-		s := strings.TrimSpace(string(b))
-		if s == "" {
-			return false
-		}
-		childPID, _ = strconv.Atoi(s)
-		return childPID > 0 && processAlive(childPID)
-	}, 20*time.Second, 200*time.Millisecond, "child process should start")
-
-	return childPID
-}
-
-// TestGroupClosePropagatesToOrphan covers what the per-step Killer cannot: a
-// completed step's orphan, reachable only by closing the job object.
 func TestGroupClosePropagatesToOrphan(t *testing.T) {
 	group, err := NewGroup()
 	require.NoError(t, err)
 	t.Cleanup(func() { _ = group.Close() })
 
-	cmd, pidFile := startOrphanMaker(t)
+	cmd, ready := newTestProcess(t, "orphan", false)
+	require.NoError(t, cmd.Start())
 	require.NoError(t, group.Assign(cmd.Process))
 
-	childPID := awaitChildPID(t, pidFile)
+	childPID := ready()
 
-	require.NoError(t, cmd.Wait()) // the step process exits cleanly, like a passing step
+	require.NoError(t, cmd.Wait())
 	require.Eventually(t, func() bool {
 		return !processAlive(cmd.Process.Pid)
 	}, 20*time.Second, 200*time.Millisecond, "the step process should have exited on its own")

internal/pkg/process/killer_windows_test.go

@@ -4,9 +4,6 @@
 package process
 
 import (
-	"fmt"
-	"os/exec"
-	"path/filepath"
 	"testing"
 	"time"
 
@@ -29,20 +26,18 @@ func processAlive(pid int) bool {
 }
 
 func TestKillerKillsTree(t *testing.T) {
-	pidFile := filepath.Join(t.TempDir(), "child.pid")
-
-	script := fmt.Sprintf(
-		`$c = Start-Process powershell -PassThru -ArgumentList '-NoProfile','-Command','Start-Sleep -Seconds 600'; `+
-			`Set-Content -LiteralPath %q -Value $c.Id; Start-Sleep -Seconds 600`, pidFile)
-	cmd := exec.Command("powershell.exe", "-NoProfile", "-Command", script)
+	cmd, ready := newTestProcess(t, "parent", false)
 	require.NoError(t, cmd.Start())
-	t.Cleanup(func() { _ = cmd.Process.Kill() })
 
 	killer, err := NewKiller(cmd.Process)
 	require.NoError(t, err)
-	defer killer.Close()
+	t.Cleanup(func() {
+		_ = killer.Kill()
+		_ = killer.Close()
+	})
 
-	childPID := awaitChildPID(t, pidFile)
+	childPID := ready()
+	require.True(t, processAlive(childPID), "child process should start")
 
 	require.NoError(t, killer.Kill())
 

internal/pkg/process/leftover_others.go

@@ -7,8 +7,6 @@ package process
 
 import "context"
 
-// KillProcessesWithCWDUnder is a no-op outside Windows: an open handle does not
-// block os.RemoveAll there.
-func KillProcessesWithCWDUnder(_ context.Context, _ []string) (int, error) {
+func KillProcessesWithPaths(_ctx context.Context, _dirs []string, _trackingID string) (int, error) {
 	return 0, nil
 }

internal/pkg/process/leftover_windows.go

@@ -8,16 +8,14 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"strings"
 	"unsafe"
 
 	"golang.org/x/sys/windows"
 )
 
-// KillProcessesWithCWDUnder terminates every process in the runner's session
-// whose cwd is one of dirs or below, catching leftovers the path scan misses
-// (Win32_Process exposes no cwd) that still pin a handle. Best-effort.
-func KillProcessesWithCWDUnder(ctx context.Context, dirs []string) (int, error) {
-	if len(dirs) == 0 {
+func KillProcessesWithPaths(ctx context.Context, dirs []string, trackingID string) (int, error) {
+	if len(dirs) == 0 || trackingID == "" {
 		return 0, nil
 	}
 
@@ -38,7 +36,6 @@ func KillProcessesWithCWDUnder(ctx context.Context, dirs []string) (int, error)
 		if ctx.Err() != nil {
 			break
 		}
-		// Never touch ourselves, System Idle (0) or System (4).
 		if pid == self || pid == 0 || pid == 4 {
 			continue
 		}
@@ -46,7 +43,7 @@ func KillProcessesWithCWDUnder(ctx context.Context, dirs []string) (int, error)
 		if err := windows.ProcessIdToSessionId(pid, &session); err != nil || session != ownSession {
 			continue
 		}
-		ok, err := terminateIfCWDUnder(pid, dirs)
+		ok, err := terminateIfPathsMatch(pid, dirs, trackingID)
 		if err != nil {
 			errs = append(errs, err)
 			continue
@@ -59,29 +56,50 @@ func KillProcessesWithCWDUnder(ctx context.Context, dirs []string) (int, error)
 	return killed, errors.Join(errs...)
 }
 
-// terminateIfCWDUnder opens pid once and both reads its cwd and terminates it
-// through that one handle, so a PID recycled between the two cannot be hit.
-func terminateIfCWDUnder(pid uint32, dirs []string) (bool, error) {
-	h, err := windows.OpenProcess(windows.PROCESS_QUERY_INFORMATION|windows.PROCESS_VM_READ|windows.PROCESS_TERMINATE, false, pid)
+func terminateIfPathsMatch(pid uint32, dirs []string, trackingID string) (bool, error) {
+	handle, err := windows.OpenProcess(windows.PROCESS_QUERY_INFORMATION|windows.PROCESS_VM_READ|windows.PROCESS_TERMINATE, false, pid)
 	if err != nil {
-		return false, nil // best-effort: gone, higher integrity, or another user
-	}
-	defer func() { _ = windows.CloseHandle(h) }()
-
-	cwd, err := processCWDHandle(h)
-	if err != nil || cwd == "" {
 		return false, nil
 	}
+	defer func() { _ = windows.CloseHandle(handle) }()
 
-	for _, d := range dirs {
-		if dirContainsPath(d, cwd) {
-			if err := windows.TerminateProcess(h, 1); err != nil {
-				return false, fmt.Errorf("terminate pid %d: %w", pid, err)
+	params, err := processParametersHandle(handle)
+	if err != nil {
+		return false, nil
+	}
+	matches := false
+fields:
+	for _, field := range []struct {
+		offset  uintptr
+		wow64   uintptr
+		command bool
+	}{
+		{unsafe.Offsetof(windows.RTL_USER_PROCESS_PARAMETERS{}.CurrentDirectory), 0x24, false},
+		{unsafe.Offsetof(windows.RTL_USER_PROCESS_PARAMETERS{}.ImagePathName), 0x38, false},
+		{unsafe.Offsetof(windows.RTL_USER_PROCESS_PARAMETERS{}.CommandLine), 0x40, true},
+	} {
+		value, err := params.unicodeString(handle, field.offset, field.wow64)
+		if err != nil {
+			continue
+		}
+		for _, dir := range dirs {
+			if !field.command && dirContainsPath(dir, value) || field.command && strings.Contains(strings.ToLower(value), strings.ToLower(strings.TrimRight(dir, `\/`)+`\`)) {
+				matches = true
+				break fields
 			}
-			return true, nil
 		}
 	}
-	return false, nil
+	if !matches {
+		return false, nil
+	}
+	value, err := params.environmentVariable(handle, "RUNNER_TRACKING_ID")
+	if err != nil || value != trackingID {
+		return false, nil
+	}
+	if err := windows.TerminateProcess(handle, 1); err != nil {
+		return false, fmt.Errorf("terminate pid %d: %w", pid, err)
+	}
+	return true, nil
 }
 
 // listProcessIDs returns the PIDs of every process in a Toolhelp snapshot.
@@ -107,65 +125,135 @@ func listProcessIDs() ([]uint32, error) {
 	return pids, nil
 }
 
-// processCWDHandle reads a process's working directory from its PEB (walking
-// PEB -> ProcessParameters -> CurrentDirectory.DosPath). h must carry
-// PROCESS_QUERY_INFORMATION|PROCESS_VM_READ.
-func processCWDHandle(h windows.Handle) (string, error) {
+type remoteParameters struct {
+	address uintptr
+	wow64   bool
+}
+
+func processParametersHandle(handle windows.Handle) (remoteParameters, error) {
 	var pbi windows.PROCESS_BASIC_INFORMATION
 	var retLen uint32
-	if err := windows.NtQueryInformationProcess(h, windows.ProcessBasicInformation, unsafe.Pointer(&pbi), uint32(unsafe.Sizeof(pbi)), &retLen); err != nil {
-		return "", err
-	}
-	if pbi.PebBaseAddress == nil {
-		return "", errors.New("nil PEB base address")
+	if err := windows.NtQueryInformationProcess(handle, windows.ProcessBasicInformation, unsafe.Pointer(&pbi), uint32(unsafe.Sizeof(pbi)), &retLen); err != nil {
+		return remoteParameters{}, err
 	}
 	pebAddr := uintptr(unsafe.Pointer(pbi.PebBaseAddress))
-
-	paramsAddr, err := readRemotePtr(h, pebAddr+unsafe.Offsetof(windows.PEB{}.ProcessParameters))
-	if err != nil || paramsAddr == 0 {
-		return "", err
+	wow64 := false
+	if unsafe.Sizeof(uintptr(0)) == 8 {
+		var peb32 uintptr
+		if err := windows.NtQueryInformationProcess(handle, windows.ProcessWow64Information, unsafe.Pointer(&peb32), uint32(unsafe.Sizeof(peb32)), &retLen); err != nil {
+			return remoteParameters{}, err
+		}
+		if peb32 != 0 {
+			pebAddr = peb32
+			wow64 = true
+		}
 	}
+	if pebAddr == 0 {
+		return remoteParameters{}, errors.New("nil PEB base address")
+	}
+	params := remoteParameters{wow64: wow64}
+	address, err := params.pointer(handle, pebAddr+params.offset(unsafe.Offsetof(windows.PEB{}.ProcessParameters), 0x10))
+	if err != nil {
+		return remoteParameters{}, err
+	}
+	if address == 0 {
+		return remoteParameters{}, errors.New("nil process parameters")
+	}
+	params.address = address
+	return params, nil
+}
 
-	// DosPath is the leading NTUnicodeString of CURDIR, so it shares CurrentDirectory's address.
-	dosPathAddr := paramsAddr + unsafe.Offsetof(windows.RTL_USER_PROCESS_PARAMETERS{}.CurrentDirectory)
-	length, err := readRemoteU16(h, dosPathAddr+unsafe.Offsetof(windows.NTUnicodeString{}.Length))
+func (p remoteParameters) offset(native, wow64 uintptr) uintptr {
+	if p.wow64 {
+		return wow64
+	}
+	return native
+}
+
+func (p remoteParameters) pointer(handle windows.Handle, address uintptr) (uintptr, error) {
+	var value uintptr
+	size := unsafe.Sizeof(value)
+	if p.wow64 {
+		size = 4
+	}
+	var read uintptr
+	if err := windows.ReadProcessMemory(handle, address, (*byte)(unsafe.Pointer(&value)), size, &read); err != nil {
+		return 0, err
+	}
+	if read != size {
+		return 0, errors.New("short pointer read")
+	}
+	return value, nil
+}
+
+func (p remoteParameters) unicodeString(handle windows.Handle, native, wow64 uintptr) (string, error) {
+	address := p.address + p.offset(native, wow64)
+	length, err := readRemoteU16(handle, address)
 	if err != nil || length == 0 {
 		return "", err
 	}
-	bufAddr, err := readRemotePtr(h, dosPathAddr+unsafe.Offsetof(windows.NTUnicodeString{}.Buffer))
-	if err != nil || bufAddr == 0 {
+	buffer, err := p.pointer(handle, address+p.offset(unsafe.Offsetof(windows.NTUnicodeString{}.Buffer), 4))
+	if err != nil {
 		return "", err
 	}
-
-	u16 := make([]uint16, (length+1)/2) // round up so an odd Length cannot overflow the buffer
-	var n uintptr
-	if err := windows.ReadProcessMemory(h, bufAddr, (*byte)(unsafe.Pointer(&u16[0])), uintptr(length), &n); err != nil {
+	value := make([]uint16, (int(length)+1)/2)
+	var read uintptr
+	if err := windows.ReadProcessMemory(handle, buffer, (*byte)(unsafe.Pointer(&value[0])), uintptr(length), &read); err != nil {
 		return "", err
 	}
-	if n != uintptr(length) {
-		return "", errors.New("short read of working directory")
+	if read != uintptr(length) {
+		return "", errors.New("short string read")
 	}
-	return windows.UTF16ToString(u16), nil
+	return windows.UTF16ToString(value), nil
 }
 
-// readRemotePtr reads a single pointer-sized value from another process.
-func readRemotePtr(h windows.Handle, addr uintptr) (uintptr, error) {
-	var v uintptr
-	var n uintptr
-	if err := windows.ReadProcessMemory(h, addr, (*byte)(unsafe.Pointer(&v)), unsafe.Sizeof(v), &n); err != nil {
-		return 0, err
+func (p remoteParameters) environmentVariable(handle windows.Handle, name string) (string, error) {
+	address, err := p.pointer(handle, p.address+p.offset(unsafe.Offsetof(windows.RTL_USER_PROCESS_PARAMETERS{}.Environment), 0x48))
+	if err != nil || address == 0 {
+		return "", err
 	}
-	if n != unsafe.Sizeof(v) {
-		return 0, errors.New("short pointer read")
+	var entry []uint16
+	for consumed := uintptr(0); consumed < 32*1024*1024; {
+		var region windows.MemoryBasicInformation
+		if err := windows.VirtualQueryEx(handle, address+consumed, &region, unsafe.Sizeof(region)); err != nil {
+			return "", err
+		}
+		size := min(uintptr(4096), region.BaseAddress+region.RegionSize-address-consumed)
+		if size < 2 {
+			return "", errors.New("invalid environment region")
+		}
+		buffer := make([]uint16, size/2)
+		var read uintptr
+		if err := windows.ReadProcessMemory(handle, address+consumed, (*byte)(unsafe.Pointer(&buffer[0])), uintptr(len(buffer)*2), &read); err != nil {
+			return "", err
+		}
+		if read != uintptr(len(buffer)*2) {
+			return "", errors.New("short environment read")
+		}
+		for _, value := range buffer {
+			if value != 0 {
+				entry = append(entry, value)
+				continue
+			}
+			if len(entry) == 0 {
+				return "", nil
+			}
+			key, value, ok := strings.Cut(windows.UTF16ToString(entry), "=")
+			if ok && strings.EqualFold(key, name) {
+				return value, nil
+			}
+			entry = entry[:0]
+		}
+		consumed += read
 	}
-	return v, nil
+	return "", errors.New("environment exceeds read limit")
 }
 
 // readRemoteU16 reads a single uint16 from another process.
-func readRemoteU16(h windows.Handle, addr uintptr) (uint16, error) {
+func readRemoteU16(handle windows.Handle, addr uintptr) (uint16, error) {
 	var v uint16
 	var n uintptr
-	if err := windows.ReadProcessMemory(h, addr, (*byte)(unsafe.Pointer(&v)), unsafe.Sizeof(v), &n); err != nil {
+	if err := windows.ReadProcessMemory(handle, addr, (*byte)(unsafe.Pointer(&v)), unsafe.Sizeof(v), &n); err != nil {
 		return 0, err
 	}
 	if n != unsafe.Sizeof(v) {

internal/pkg/process/leftover_windows_test.go

@@ -7,21 +7,21 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"runtime"
 	"syscall"
 	"testing"
 	"time"
+	"unsafe"
 
 	"github.com/stretchr/testify/require"
 	"golang.org/x/sys/windows"
 )
 
-// startSleeperIn launches a long-running child whose cwd is dir but whose
-// executable lives outside it — what the path scan cannot see.
-func startSleeperIn(t *testing.T, dir string) *exec.Cmd {
+func startSleeperIn(t *testing.T, system, dir, trackingID string) *exec.Cmd {
 	t.Helper()
-	ping := filepath.Join(os.Getenv("SystemRoot"), "System32", "ping.exe")
-	cmd := exec.Command(ping, "-n", "60", "127.0.0.1")
+	cmd := exec.Command(filepath.Join(os.Getenv("SystemRoot"), system, "ping.exe"), "-n", "60", "127.0.0.1")
 	cmd.Dir = dir
+	cmd.Env = append(os.Environ(), "RUNNER_TRACKING_ID="+trackingID)
 	cmd.SysProcAttr = &syscall.SysProcAttr{HideWindow: true}
 	require.NoError(t, cmd.Start())
 	t.Cleanup(func() {
@@ -31,19 +31,19 @@ func startSleeperIn(t *testing.T, dir string) *exec.Cmd {
 	return cmd
 }
 
-// processCWD opens pid and reads its working directory. Test-only; the reaper
-// shares one handle across read and kill via processCWDHandle.
 func processCWD(pid uint32) (string, error) {
 	h, err := windows.OpenProcess(windows.PROCESS_QUERY_INFORMATION|windows.PROCESS_VM_READ, false, pid)
 	if err != nil {
 		return "", err
 	}
 	defer func() { _ = windows.CloseHandle(h) }()
-	return processCWDHandle(h)
+	params, err := processParametersHandle(h)
+	if err != nil {
+		return "", err
+	}
+	return params.unicodeString(h, unsafe.Offsetof(windows.RTL_USER_PROCESS_PARAMETERS{}.CurrentDirectory), 0x24)
 }
 
-// awaitCWD waits until pid's PEB reports a readable cwd (not populated the
-// instant the process starts) and returns it.
 func awaitCWD(t *testing.T, pid int) string {
 	t.Helper()
 	var cwd string
@@ -55,36 +55,52 @@ func awaitCWD(t *testing.T, pid int) string {
 	return cwd
 }
 
-func TestProcessCWDReadsWorkingDirectory(t *testing.T) {
-	dir := t.TempDir()
-	cmd := startSleeperIn(t, dir)
-	cwd := awaitCWD(t, cmd.Process.Pid)
-	require.True(t, dirContainsPath(dir, cwd), "cwd %q should be within %q", cwd, dir)
+func TestKillProcessesWithPathsTracking(t *testing.T) {
+	for _, system := range []string{"System32", "SysWOW64"} {
+		for _, trackingID := range []string{"leftover-test", "", "another-job"} {
+			t.Run(system+"/tracking="+trackingID, func(t *testing.T) {
+				if system == "SysWOW64" {
+					if runtime.GOARCH != "amd64" && runtime.GOARCH != "arm64" {
+						t.Skip("needs a 64-bit runner")
+					}
+					if _, err := os.Stat(filepath.Join(os.Getenv("SystemRoot"), system, "ping.exe")); err != nil {
+						t.Skip("32-bit Windows tools unavailable")
+					}
+				}
+				dir := t.TempDir()
+				cmd := startSleeperIn(t, system, dir, trackingID)
+				require.True(t, dirContainsPath(dir, awaitCWD(t, cmd.Process.Pid)))
+				killed, err := KillProcessesWithPaths(t.Context(), []string{t.TempDir()}, "leftover-test")
+				require.NoError(t, err)
+				require.Zero(t, killed)
+				killed, err = KillProcessesWithPaths(t.Context(), []string{dir}, "leftover-test")
+				require.NoError(t, err)
+				if trackingID == "leftover-test" {
+					require.Equal(t, 1, killed)
+					require.Eventually(t, func() bool {
+						return !processAlive(cmd.Process.Pid)
+					}, 5*time.Second, 50*time.Millisecond)
+				} else {
+					require.Zero(t, killed)
+					require.True(t, processAlive(cmd.Process.Pid))
+				}
+			})
+		}
+	}
 }
 
-func TestKillProcessesWithCWDUnderTerminatesMatch(t *testing.T) {
-	dir := t.TempDir()
-	// Executable outside dir and arguments carry no workspace path, so only the
-	// working directory links this process to dir.
-	cmd := startSleeperIn(t, dir)
-	awaitCWD(t, cmd.Process.Pid)
-
-	killed, err := KillProcessesWithCWDUnder(t.Context(), []string{dir})
+func TestKillProcessesWithPathsCommandLine(t *testing.T) {
+	workspace := t.TempDir()
+	cmd, ready := newTestProcess(t, "child", false)
+	cmd.Dir = t.TempDir()
+	cmd.Args = append(cmd.Args, filepath.Join(workspace, "reference"))
+	cmd.Env = append(cmd.Env, "RUNNER_TRACKING_ID=command-test")
+	require.NoError(t, cmd.Start())
+	ready()
+	killed, err := KillProcessesWithPaths(t.Context(), []string{workspace}, "command-test")
 	require.NoError(t, err)
-	require.GreaterOrEqual(t, killed, 1)
-
+	require.Equal(t, 1, killed)
 	require.Eventually(t, func() bool {
 		return !processAlive(cmd.Process.Pid)
-	}, 5*time.Second, 50*time.Millisecond, "matched process should exit")
-}
-
-func TestKillProcessesWithCWDUnderSparesUnrelated(t *testing.T) {
-	workspace := t.TempDir()
-	elsewhere := t.TempDir()
-	cmd := startSleeperIn(t, elsewhere)
-	awaitCWD(t, cmd.Process.Pid)
-
-	_, err := KillProcessesWithCWDUnder(t.Context(), []string{workspace})
-	require.NoError(t, err)
-	require.True(t, processAlive(cmd.Process.Pid), "process outside owned dirs must be spared")
+	}, 5*time.Second, 50*time.Millisecond)
 }

internal/pkg/process/treekill.go

@@ -32,7 +32,8 @@ const treeKillWaitDelay = 10 * time.Second
 // Callers still set cmd.SysProcAttr (via SysProcAttr) themselves, because the
 // value differs between the plain and PTY execution paths.
 type TreeKill struct {
-	killer atomic.Pointer[Killer]
+	killer        atomic.Pointer[Killer]
+	KeepLeftovers bool
 }
 
 // NewTreeKill sets cmd.Cancel and cmd.WaitDelay. Call it before cmd.Start, then
@@ -72,13 +73,13 @@ func (t *TreeKill) Capture(p *os.Process) (*Killer, error) {
 	return k, nil
 }
 
-// Wait is cmd.Wait, but like GitHub's runner a leftover holding a successful command's output does not fail it, and is killed only on Windows.
+// Wait is cmd.Wait, but like GitHub's runner a leftover holding a successful command's output does not fail it.
 func (t *TreeKill) Wait(ctx context.Context, cmd *exec.Cmd) error {
 	err := cmd.Wait()
 	if !errors.Is(err, exec.ErrWaitDelay) || ctx.Err() != nil {
 		return err
 	}
-	if runtime.GOOS == "windows" {
+	if runtime.GOOS == "windows" && !t.KeepLeftovers {
 		_ = t.killer.Load().Kill()
 	}
 	return nil

internal/pkg/process/treekill_test.go

@@ -5,8 +5,11 @@ package process
 
 import (
 	"context"
+	"fmt"
 	"io"
+	"os"
 	"os/exec"
+	"os/signal"
 	"runtime"
 	"testing"
 	"time"
@@ -60,11 +63,10 @@ func TestTreeKillWaitWithLeftoverHoldingOutput(t *testing.T) {
 }
 
 func TestTreeKillCaptureStoresKiller(t *testing.T) {
-	cmd := exec.CommandContext(t.Context(), "sleep", "10")
-	cmd.SysProcAttr = SysProcAttr("", false)
+	cmd, ready := newTestProcess(t, "child", false)
 	tk := NewTreeKill(cmd)
 	require.NoError(t, cmd.Start())
-	defer func() { _ = cmd.Wait() }()
+	ready()
 
 	killer, err := tk.Capture(cmd.Process)
 	require.NoError(t, err)
@@ -72,3 +74,84 @@ func TestTreeKillCaptureStoresKiller(t *testing.T) {
 	require.NoError(t, cmd.Cancel())
 	require.NoError(t, killer.Close())
 }
+
+func newTestProcess(t *testing.T, mode string, copiedOutput bool) (*exec.Cmd, func() int) {
+	t.Helper()
+	ctx, cancel := context.WithTimeout(t.Context(), 20*time.Second)
+	t.Cleanup(cancel)
+	cmd := exec.CommandContext(ctx, os.Args[0], "-test.run=^TestProcessHelper$")
+	cmd.Env = append(os.Environ(), "GITEA_PROCESS_HELPER="+mode)
+	cmd.SysProcAttr = SysProcAttr("", false)
+	cmd.Stderr = os.Stderr
+	input, err := cmd.StdinPipe()
+	require.NoError(t, err)
+	var output io.ReadCloser
+	if copiedOutput {
+		var writer *io.PipeWriter
+		output, writer = io.Pipe()
+		cmd.Stdout = writer
+	} else {
+		output, err = cmd.StdoutPipe()
+		require.NoError(t, err)
+	}
+	stop := context.AfterFunc(ctx, func() {
+		_ = input.Close()
+		_ = output.Close()
+	})
+	t.Cleanup(func() {
+		stop()
+		_ = input.Close()
+		_ = output.Close()
+		if cmd.Process != nil {
+			_ = cmd.Process.Kill()
+			_ = cmd.Wait()
+		}
+	})
+	return cmd, func() int {
+		t.Helper()
+		_, err := input.Write([]byte{1})
+		require.NoError(t, err)
+		var childPID int
+		_, err = fmt.Fscan(output, &childPID)
+		require.NoError(t, err, "process should report its PID")
+		require.Positive(t, childPID)
+		return childPID
+	}
+}
+
+func TestProcessHelper(t *testing.T) {
+	mode := os.Getenv("GITEA_PROCESS_HELPER")
+	switch mode {
+	case "":
+		return
+	case "orphan-child":
+		interrupt := make(chan os.Signal, 1)
+		signal.Notify(interrupt, os.Interrupt)
+		_, err := fmt.Fprintln(os.Stdout, os.Getpid())
+		require.NoError(t, err)
+		<-interrupt
+	case "child":
+		_, err := fmt.Fprintln(os.Stdout, os.Getpid())
+		require.NoError(t, err)
+		_, err = io.Copy(io.Discard, os.Stdin)
+		require.NoError(t, err)
+	default:
+		var start [1]byte
+		_, err := io.ReadFull(os.Stdin, start[:])
+		require.NoError(t, err)
+		child := exec.Command(os.Args[0], "-test.run=^TestProcessHelper$")
+		child.Env = append(os.Environ(), "GITEA_PROCESS_HELPER=child")
+		if mode == "orphan" {
+			child.Env = append(os.Environ(), "GITEA_PROCESS_HELPER=orphan-child")
+		}
+		child.Stdin = os.Stdin
+		child.Stdout = os.Stdout
+		child.Stderr = os.Stderr
+		require.NoError(t, child.Start())
+		if mode == "orphan" {
+			os.Exit(0)
+		}
+		require.NoError(t, child.Wait())
+	}
+	os.Exit(0)
+}

internal/pkg/process/treekill_windows_test.go

@@ -0,0 +1,45 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package process
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	"golang.org/x/sys/windows"
+)
+
+func TestTreeKillWaitTrackingLeftoverOutput(t *testing.T) {
+	for _, keep := range []bool{false, true} {
+		t.Run(map[bool]string{false: "tracked", true: "opted out"}[keep], func(t *testing.T) {
+			cmd, ready := newTestProcess(t, "orphan", true)
+			tree := NewTreeKill(cmd)
+			tree.KeepLeftovers = keep
+			cmd.WaitDelay = 50 * time.Millisecond
+			require.NoError(t, cmd.Start())
+			killer, err := tree.Capture(cmd.Process)
+			require.NoError(t, err)
+			defer killer.Close()
+			childPID := ready()
+			handle, err := windows.OpenProcess(windows.SYNCHRONIZE|windows.PROCESS_TERMINATE, false, uint32(childPID))
+			require.NoError(t, err)
+			t.Cleanup(func() {
+				_ = windows.TerminateProcess(handle, 1)
+				_, _ = windows.WaitForSingleObject(handle, 5000)
+				_ = windows.CloseHandle(handle)
+			})
+			require.NoError(t, tree.Wait(t.Context(), cmd))
+			if keep {
+				result, err := windows.WaitForSingleObject(handle, 0)
+				require.NoError(t, err)
+				require.EqualValues(t, windows.WAIT_TIMEOUT, result)
+			} else {
+				result, err := windows.WaitForSingleObject(handle, 5000)
+				require.NoError(t, err)
+				require.EqualValues(t, windows.WAIT_OBJECT_0, result)
+			}
+		})
+	}
+}

scripts/test-windows-setup.ps1

@@ -0,0 +1,29 @@
+$ErrorActionPreference = 'Stop'
+$ProgressPreference = 'SilentlyContinue'
+$shared = '\\host.lan\Data'
+try {
+    Write-Output '==> Setting up Windows'
+    Set-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem LongPathsEnabled 1
+    foreach ($tool in @(
+            @('git.7z.exe', 'https://github.com/git-for-windows/git/releases/download/v2.56.0.windows.3/PortableGit-2.56.0.3-64-bit.7z.exe', '4fc27b779829a36df77911e3f4dea09c66c790dd6c5f7dfa3b6a5479f1fe354f'),
+            @('node.zip', 'https://nodejs.org/dist/v24.22.1/node-v24.22.1-win-x64.zip', 'd2046d28c2c3dcd211ac5145c0bf30e2047ef9dfb306693c8c6e2eccd8b95fa5'),
+            @('pwsh.zip', 'https://github.com/PowerShell/PowerShell/releases/download/v7.6.8/PowerShell-7.6.8-win-x64.zip', 'b9f074f923c499b51ec99d313da8e9ae90d17a9f3adf00c73d6189f34d908528'))) {
+        Write-Output "==> Downloading $($tool[1])"
+        Invoke-WebRequest -UseBasicParsing $tool[1] -OutFile "$env:TEMP\$($tool[0])"
+        if ((Get-FileHash "$env:TEMP\$($tool[0])").Hash -ne $tool[2]) { throw "checksum mismatch for $($tool[1])" }
+    }
+    Write-Output '==> Extracting git, node and pwsh'
+    New-Item -ItemType Directory C:\pwsh | Out-Null
+    @(
+        Start-Process "$env:TEMP\git.7z.exe" -ArgumentList '-oC:\git', '-y' -PassThru
+        Start-Process tar.exe -ArgumentList '-xf', "$env:TEMP\node.zip", '-C', 'C:\' -PassThru -NoNewWindow
+        Start-Process tar.exe -ArgumentList '-xf', "$env:TEMP\pwsh.zip", '-C', 'C:\pwsh' -PassThru -NoNewWindow
+    ) | Wait-Process
+    Rename-Item (Resolve-Path C:\node-*-win-x64).Path C:\node
+    $env:Path = "C:\git\cmd;C:\git\bin;C:\pwsh;C:\node;$env:Path"
+    Get-Command git, bash, node, pwsh | Out-Null
+} catch {
+    $_ | Out-String | Tee-Object "$shared\error.txt"
+    Set-Content "$shared\exitcode" 1
+    exit 1
+}

scripts/test-windows.ps1

@@ -0,0 +1,31 @@
+$ErrorActionPreference = 'Stop'
+$ProgressPreference = 'SilentlyContinue'
+$results = '\\host.lan\Data'
+$root = $PSScriptRoot
+try {
+    New-Item -ItemType Directory "$root\logs" | Out-Null
+    $env:Path = "C:\git\cmd;C:\git\bin;C:\pwsh;C:\node;$env:Path"
+    git config --global --add safe.directory C:/OEM/src # setup copied it as SYSTEM, the tests run as the logged-on user
+
+    $failed = 0
+    Write-Output "==> Running $((Get-Content "$root\tests.txt").Count) test binaries on $([Environment]::ProcessorCount) cores"
+    Get-Content "$root\tests.txt" | ForEach-Object -ThrottleLimit ([Environment]::ProcessorCount) -Parallel {
+        $binary, $package = $_ -split ' ', 2
+        $started = Get-Date
+        Set-Location "$using:root\src\$package"
+        cmd.exe /d /c "$using:root\bin\$binary -test.v -test.timeout=60m -test.parallel=8 > $using:root\logs\$($package -replace '/', '-').log 2>&1"
+        [pscustomobject]@{ Package = $package; ExitCode = $LASTEXITCODE; Seconds = [int]((Get-Date) - $started).TotalSeconds }
+    } | ForEach-Object {
+        $line = "ok $($_.Package) $($_.Seconds)s"
+        if ($_.ExitCode -ne 0) {
+            $line = "FAIL $($_.Package) $($_.Seconds)s exit $($_.ExitCode)"
+            $failed = 1
+        }
+        Add-Content "$results\summary.txt" $line
+    }
+    Copy-Item "$root\logs\*" $results
+} catch {
+    $_ | Out-String | Tee-Object "$results\error.txt"
+    $failed = 1
+}
+Set-Content "$results\exitcode" $failed

scripts/test-windows.sh

@@ -0,0 +1,90 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+image="${WINDOWS_TEST_IMAGE:?}"
+timeout="${WINDOWS_TEST_TIMEOUT:-165}"
+name="gitea-runner-windows-test-$$"
+work="$(mktemp -d)"
+
+cleanup() {
+  docker rm -fv "$name" >/dev/null 2>&1 || true
+  rm -rf "$work"
+}
+trap cleanup EXIT
+
+if [ "$(docker info -f '{{.Architecture}}')" != x86_64 ]; then
+  echo "error: the Windows test VM needs an amd64 docker host" >&2
+  exit 1
+fi
+
+echo "==> Building Windows test binaries"
+oem="$work/oem"
+mkdir -p "$oem/bin" "$oem/src" "$work/shared"
+module="$(go list -m)"
+packages="$(GOOS=windows go list -f '{{if or .TestGoFiles .XTestGoFiles}}{{.ImportPath}}{{end}}' ./...)"
+GOOS=windows GOARCH=amd64 go test -c -ldflags='-s -w' -o "$oem/bin/" $packages
+for package in $packages; do
+  echo "${package##*/}.test.exe ${package#"$module"/}"
+done > "$oem/tests.txt"
+git ls-files -z --cached --others --exclude-standard | while IFS= read -r -d '' file; do
+  if [ -e "$file" ]; then printf '%s\0' "$file"; fi
+done | tar --null -T - -cf - | tar -xf - -C "$oem/src"
+git -C "$oem/src" init -q -b main # a repository like the CI checkout, for the tests that read the github context from it
+git -C "$oem/src" add -Af .
+git -C "$oem/src" -c user.name=test -c user.email=test@localhost -c commit.gpgsign=false -c core.hooksPath=/dev/null commit -qm test
+git -C "$oem/src" remote add origin https://gitea.com/gitea/runner
+cp scripts/test-windows-setup.ps1 scripts/test-windows.ps1 "$oem/"
+sed 's/$/\r/' > "$oem/install.bat" <<'EOF' # a policy turns off real-time scanning, AMSI blocks scripts that do it
+@echo off
+set log=\\host.lan\Data\install.log
+echo ==^> install.bat started at %TIME% >> %log%
+reg.exe add "HKLM\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection" /v DisableRealtimeMonitoring /t REG_DWORD /d 1 /f > nul
+powershell.exe -NoProfile -ExecutionPolicy Bypass -File C:\OEM\test-windows-setup.ps1 >> %log% 2>&1
+echo ==^> setup exited with %ERRORLEVEL% >> %log%
+if %ERRORLEVEL% equ 0 C:\pwsh\pwsh.exe -NoProfile -ExecutionPolicy Bypass -File C:\OEM\test-windows.ps1 >> %log% 2>&1
+if not exist \\host.lan\Data\exitcode (echo 1)> \\host.lan\Data\exitcode
+shutdown.exe /s /t 600
+EOF
+
+kvm=Y cores="$(nproc)"
+if ! docker run --rm --privileged --entrypoint sh "$image" -c 'test -w /dev/kvm'; then
+  kvm=N cores=4 # more emulated vCPUs slow Windows down
+  echo "==> The docker host has no usable /dev/kvm, Windows runs emulated and much slower"
+fi
+
+echo "==> Installing Windows"
+docker create --rm --name "$name" --privileged -e VERSION=2025 -e EDITION=core -e KVM="$kvm" -e CPU_CORES="$cores" -e RAM_SIZE=8G \
+  -e DISK_SIZE=32G -e DISK_CACHE=unsafe -e DISK_IO=threads --entrypoint timeout "$image" "$((timeout + 10))m" /usr/bin/tini -s /run/entry.sh >/dev/null # the timeout stops the VM even when this script is killed before its cleanup runs
+docker cp "$oem" "$name:/oem"
+docker cp "$work/shared" "$name:/shared"
+docker start "$name" >/dev/null
+docker logs -f "$name" &
+while sleep 10 && docker container inspect "$name" >/dev/null 2>&1; do
+  if ((SECONDS % 300 < 10)); then
+    echo "==> $((SECONDS / 60))m elapsed, VM disk $(docker exec "$name" du -sh /storage | cut -f1)"
+  fi
+done &
+docker exec "$name" sh -c 'cd /shared && touch install.log summary.txt && tail -qf install.log summary.txt' &
+
+if ! timeout "${timeout}m" docker exec "$name" sh -c 'until [ -f /shared/exitcode ]; do sleep 10; done'; then
+  echo "Windows stopped or did not finish the tests within $timeout minutes" >&2
+  exit 1
+fi
+results="$work/results"
+docker cp "$name:/shared" "$results"
+
+tr -d '\r' < "$results/summary.txt" | while read -r result package _; do
+  if [ "$result" = FAIL ]; then
+    echo "::group::$package"
+    cat "$results/${package//\//-}.log"
+    echo "::endgroup::"
+  fi
+done
+if [ -f "$results/error.txt" ]; then
+  cat "$results/error.txt" >&2
+fi
+echo "==> Slowest tests"
+find "$results" -name '*.log' -exec cat {} + | tr -d '\r' | sed -nE 's/^--- (PASS|FAIL): (\S+) \(([0-9.]+)s\)$/\3 \2/p' | sort -rn | awk 'NR <= 20'
+echo "==> Packages"
+tr -d '\r' < "$results/summary.txt"
+exit "$(tr -d '\r\n' < "$results/exitcode")"