fix(test): isolate e2e task artifact caches

packages/cli/internal/platform/updatecheck/background_test.go

@@ -139,9 +139,15 @@ func TestDetachedWorkerHelper(t *testing.T) {
 		}
 		closeParent()
 		time.Sleep(100 * time.Millisecond)
-		if err := os.WriteFile(os.Getenv("ONE_UPDATE_TEST_MARKER"), []byte("finished"), 0o600); err != nil {
+		// Publish completion only after the contents are fully written and closed.
+		// Writing the marker directly lets the parent observe an empty file.
+		marker := os.Getenv("ONE_UPDATE_TEST_MARKER")
+		if err := os.WriteFile(marker+".tmp", []byte("finished"), 0o600); err != nil {
 			os.Exit(5)
 		}
+		if err := os.Rename(marker+".tmp", marker); err != nil {
+			os.Exit(6)
+		}
 		os.Exit(0)
 	}
 }

packages/cli/tests/e2e/e2e_helpers_test.go

@@ -280,6 +280,9 @@ func isolateHome(t *testing.T, dir string) {
 	for _, key := range []string{"XDG_DATA_HOME", "XDG_STATE_HOME", "MISE_CONFIG_DIR", "MISE_DATA_DIR", "MISE_STATE_DIR", "MISE_CACHE_DIR"} {
 		t.Setenv(key, filepath.Join(dir, key))
 	}
+	// CI shares task artifacts across runs, independently of MISE_CACHE_DIR.
+	// Keep that outer cache from restoring outputs into a fresh test fixture.
+	t.Setenv("MISE_TASK_CACHE_DIR", filepath.Join(dir, "mise-task-artifacts"))
 	for _, key := range []string{"CODEX_HOME", "CLAUDE_CONFIG_DIR", "VIBE_HOME"} {
 		t.Setenv(key, "")
 	}

packages/cli/tests/e2e/tasks_cache_test.go

@@ -18,6 +18,15 @@ func appendRootTaskConfig(t *testing.T, root, value string) {
 }
 
 func TestE2E_TasksRestoreArtifactsAndInvalidateRootConfiguration(t *testing.T) {
+	// CI runs race and plain suites with the same outer artifact cache. A new
+	// fixture must execute its first build even when identical artifacts exist.
+	t.Setenv("MISE_TASK_CACHE_DIR", t.TempDir())
+	for _, name := range []string{"first", "fresh-home"} {
+		t.Run(name, testTasksRestoreArtifactsAndInvalidateRootConfiguration)
+	}
+}
+
+func testTasksRestoreArtifactsAndInvalidateRootConfiguration(t *testing.T) {
 	root := buildFixture(t, true)
 	for _, project := range []struct{ name, dir string }{{"web", "apps/web"}, {"lib", "packages/lib"}} {
 		name, dir := project.name, project.dir
@@ -139,9 +148,11 @@ func TestE2E_NativeMiseIncludedTOMLTask(t *testing.T) {
 }
 
 func TestE2E_TasksReuseArtifactsAcrossCheckouts(t *testing.T) {
-	t.Setenv("MISE_TASK_CACHE_DIR", t.TempDir())
+	cache := t.TempDir()
 	for i := 0; i < 2; i++ {
 		root := buildFixture(t, true)
+		// Opt into sharing only after the fixture has isolated its home/cache.
+		t.Setenv("MISE_TASK_CACHE_DIR", cache)
 		for _, project := range []struct{ name, dir string }{{"web", "apps/web"}, {"lib", "packages/lib"}} {
 			name, dir := project.name, project.dir
 			buildWrite(t, root, dir+"/build.sh", "#!/bin/sh\nmkdir -p dist\necho portable-artifact > dist/value\necho executed >> executions\n")