Preserve child working directory in environment overlays

internal/process/process.go

@@ -6,7 +6,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"os"
 	"os/exec"
 	"sort"
 	"strings"
@@ -151,14 +150,15 @@ func newCommand(ctx context.Context, invocation Invocation) (*exec.Cmd, error) {
 	command.Dir = invocation.Dir
 	command.WaitDelay = time.Second
 	if len(invocation.Env) != 0 || len(invocation.UnsetEnv) != 0 {
-		command.Env = environmentEntries(invocation.Env, invocation.UnsetEnv)
+		// Dir contributes PWD on POSIX before explicit overrides are applied.
+		command.Env = environmentEntries(command.Environ(), invocation.Env, invocation.UnsetEnv)
 	}
 	return command, nil
 }
 
-func environmentEntries(overlay map[string]string, unset []string) []string {
-	environment := make(map[string]string, len(os.Environ())+len(overlay))
-	for _, entry := range os.Environ() {
+func environmentEntries(base []string, overlay map[string]string, unset []string) []string {
+	environment := make(map[string]string, len(base)+len(overlay))
+	for _, entry := range base {
 		key, value, ok := strings.Cut(entry, "=")
 		if ok {
 			environment[key] = value

internal/process/process_test.go

@@ -10,6 +10,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"runtime"
 	"strconv"
 	"strings"
 	"testing"
@@ -79,6 +80,50 @@ func TestRunCanRemoveInheritedEnvironment(t *testing.T) {
 	}
 }
 
+func TestRunDirectoryEnvironmentPreservesExplicitPWDSelection(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("directory-derived PWD is a POSIX behavior")
+	}
+	parent := mustGetwd(t)
+	t.Setenv("PWD", parent)
+	workdir := t.TempDir()
+	for _, test := range []struct {
+		name, override, want string
+		unset                bool
+		present              bool
+	}{
+		{name: "directory", want: workdir, present: true},
+		{name: "override", override: "selected PWD", want: "selected PWD", present: true},
+		{name: "removed", unset: true},
+		{name: "override after removal", unset: true, override: "selected PWD", want: "selected PWD", present: true},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			invocation := Invocation{
+				Args: []string{helperExecutable(t), "-test.run=TestProcessHelper", "--", "pwd"},
+				Dir:  workdir,
+				Env:  map[string]string{"RELEASEKIT_PROCESS_HELPER": "1"},
+			}
+			if test.override != "" {
+				invocation.Env["PWD"] = test.override
+			}
+			if test.unset {
+				invocation.UnsetEnv = []string{"PWD"}
+			}
+			var stdout bytes.Buffer
+			invocation.Stdout = &stdout
+			if err := Run(t.Context(), invocation); err != nil {
+				t.Fatal(err)
+			}
+			if got, want := stdout.String(), fmt.Sprintf("%s|%t", test.want, test.present); got != want {
+				t.Fatalf("child PWD = %q, want %q", got, want)
+			}
+			if os.Getenv("PWD") != parent || mustGetwd(t) != parent {
+				t.Fatal("child invocation changed the parent's directory or PWD")
+			}
+		})
+	}
+}
+
 func TestRunReportsMissingExecutable(t *testing.T) {
 	err := Run(context.Background(), Invocation{Args: []string{"releasekit-command-that-does-not-exist"}})
 	if err == nil || !strings.Contains(err.Error(), "releasekit-command-that-does-not-exist") {
@@ -378,6 +423,10 @@ func TestProcessHelper(t *testing.T) {
 	}
 	mode := args[len(args)-1]
 	switch mode {
+	case "pwd":
+		value, present := os.LookupEnv("PWD")
+		fmt.Fprintf(os.Stdout, "%s|%t", value, present)
+		os.Exit(0)
 	case "success":
 		workdir, err := os.Getwd()
 		if err != nil {