fix: respect CLAUDE_CONFIG_DIR env var for Claude config directory

internal/claude/process_manager.go

@@ -16,6 +16,7 @@ import (
 	"syscall"
 	"time"
 
+	"github.com/zhubert/plural/internal/claudeconfig"
 	"github.com/zhubert/plural/internal/paths"
 )
 
@@ -998,9 +999,9 @@ type containerRunResult struct {
 // buildContainerRunArgs constructs the arguments for `docker run` that wraps
 // the Claude CLI process inside a Docker container.
 func buildContainerRunArgs(config ProcessConfig, claudeArgs []string) (containerRunResult, error) {
-	homeDir, err := os.UserHomeDir()
+	claudeDir, err := claudeconfig.GetClaudeConfigDir()
 	if err != nil {
-		return containerRunResult{}, fmt.Errorf("failed to determine home directory: %w", err)
+		return containerRunResult{}, fmt.Errorf("failed to determine claude config directory: %w", err)
 	}
 
 	containerName := "plural-" + config.SessionID
@@ -1013,7 +1014,7 @@ func buildContainerRunArgs(config ProcessConfig, claudeArgs []string) (container
 		"run", "-i", "--rm",
 		"--name", containerName,
 		"-v", config.WorkingDir + ":/workspace",
-		"-v", homeDir + "/.claude:/home/claude/.claude-host:ro",
+		"-v", claudeDir + ":/home/claude/.claude-host:ro",
 		"-w", "/workspace",
 	}
 
@@ -1172,15 +1173,15 @@ func readKeychainOAuthToken() string {
 	return creds.ClaudeAiOauth.AccessToken
 }
 
-// credentialsFileExists checks whether ~/.claude/.credentials.json exists.
+// credentialsFileExists checks whether .credentials.json exists in the Claude config dir.
 // This file is created by "claude login" (interactive OAuth) and contains
 // refresh tokens that Claude CLI can use to obtain access tokens.
 func credentialsFileExists() bool {
-	home, err := os.UserHomeDir()
+	dir, err := claudeconfig.GetClaudeConfigDir()
 	if err != nil {
 		return false
 	}
-	_, err = os.Stat(filepath.Join(home, ".claude", ".credentials.json"))
+	_, err = os.Stat(filepath.Join(dir, ".credentials.json"))
 	return err == nil
 }
 

internal/claude/process_manager_test.go

@@ -2273,6 +2273,45 @@ func TestBuildCommandArgs_DisableStreamingChunks(t *testing.T) {
 	})
 }
 
+func TestCredentialsFileExists_WithClaudeConfigDir(t *testing.T) {
+	// Create a custom directory pointed to by CLAUDE_CONFIG_DIR
+	customDir := t.TempDir()
+	credFile := filepath.Join(customDir, ".credentials.json")
+	if err := os.WriteFile(credFile, []byte(`{"refreshToken":"test"}`), 0600); err != nil {
+		t.Fatalf("failed to create credentials file: %v", err)
+	}
+
+	t.Setenv("CLAUDE_CONFIG_DIR", customDir)
+	// Point HOME at an empty dir to ensure we're not falling back
+	t.Setenv("HOME", t.TempDir())
+
+	if !credentialsFileExists() {
+		t.Error("credentialsFileExists should return true when CLAUDE_CONFIG_DIR is set and .credentials.json exists there")
+	}
+}
+
+func TestBuildContainerRunArgs_ClaudeConfigDir(t *testing.T) {
+	// When CLAUDE_CONFIG_DIR is set, the volume mount should use that directory
+	customDir := "/custom/claude/config"
+	t.Setenv("CLAUDE_CONFIG_DIR", customDir)
+
+	config := ProcessConfig{
+		SessionID:      "test-configdir",
+		WorkingDir:     "/tmp",
+		ContainerImage: "plural-claude",
+	}
+
+	result, err := buildContainerRunArgs(config, []string{"--print"})
+	if err != nil {
+		t.Fatalf("buildContainerRunArgs failed: %v", err)
+	}
+
+	expectedMount := customDir + ":/home/claude/.claude-host:ro"
+	if !containsArg(result.Args, expectedMount) {
+		t.Errorf("args should contain volume mount %q, got: %v", expectedMount, result.Args)
+	}
+}
+
 func TestCredentialsFileExists_WithFile(t *testing.T) {
 	// Create a temp directory to act as home
 	tmpHome := t.TempDir()

internal/claudeconfig/config_dir.go

@@ -0,0 +1,20 @@
+package claudeconfig
+
+import (
+	"os"
+	"path/filepath"
+)
+
+// GetClaudeConfigDir returns the Claude Code configuration directory.
+// If the CLAUDE_CONFIG_DIR environment variable is set, it is used as-is.
+// Otherwise, falls back to ~/.claude.
+func GetClaudeConfigDir() (string, error) {
+	if dir := os.Getenv("CLAUDE_CONFIG_DIR"); dir != "" {
+		return dir, nil
+	}
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(home, ".claude"), nil
+}

internal/claudeconfig/config_dir_test.go

@@ -0,0 +1,51 @@
+package claudeconfig
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestGetClaudeConfigDir(t *testing.T) {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		t.Fatalf("failed to get home dir: %v", err)
+	}
+
+	tests := []struct {
+		name    string
+		envVal  string
+		want    string
+		wantErr bool
+	}{
+		{
+			name:   "env var set returns env var value",
+			envVal: "/custom/claude/config",
+			want:   "/custom/claude/config",
+		},
+		{
+			name:   "env var unset returns ~/.claude",
+			envVal: "",
+			want:   filepath.Join(home, ".claude"),
+		},
+		{
+			name:   "env var with trailing slash is returned as-is",
+			envVal: "/custom/dir/",
+			want:   "/custom/dir/",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Setenv("CLAUDE_CONFIG_DIR", tt.envVal)
+
+			got, err := GetClaudeConfigDir()
+			if (err != nil) != tt.wantErr {
+				t.Fatalf("GetClaudeConfigDir() error = %v, wantErr %v", err, tt.wantErr)
+			}
+			if got != tt.want {
+				t.Errorf("GetClaudeConfigDir() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}

internal/mcp/server.go

@@ -14,6 +14,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/zhubert/plural/internal/claudeconfig"
 	"github.com/zhubert/plural/internal/logger"
 )
 
@@ -896,16 +897,16 @@ func (s *Server) readPlanFromPath(planPath string) string {
 	return string(content)
 }
 
-// validatePlanPath ensures the given path resolves to within ~/.claude/plans/.
+// validatePlanPath ensures the given path resolves to within the Claude plans directory.
 // This prevents path traversal attacks where a malicious filePath argument
 // could read arbitrary files from the filesystem.
 func validatePlanPath(planPath string) error {
-	homeDir, err := os.UserHomeDir()
+	claudeDir, err := claudeconfig.GetClaudeConfigDir()
 	if err != nil {
-		return fmt.Errorf("cannot determine home directory: %w", err)
+		return fmt.Errorf("cannot determine claude config directory: %w", err)
 	}
 
-	allowedDir := filepath.Join(homeDir, ".claude", "plans")
+	allowedDir := filepath.Join(claudeDir, "plans")
 
 	// Clean and resolve the path to eliminate ../ traversal
 	absPath, err := filepath.Abs(planPath)

internal/mcp/server_test.go

@@ -986,6 +986,45 @@ func TestReadPlanFromPath(t *testing.T) {
 	})
 }
 
+func TestValidatePlanPath_ClaudeConfigDir(t *testing.T) {
+	// When CLAUDE_CONFIG_DIR is set, plans must be under that directory.
+	customDir := t.TempDir()
+	t.Setenv("CLAUDE_CONFIG_DIR", customDir)
+
+	plansDir := filepath.Join(customDir, "plans")
+
+	tests := []struct {
+		name    string
+		path    string
+		wantErr bool
+	}{
+		{
+			name:    "valid path in custom plans directory",
+			path:    filepath.Join(plansDir, "my-plan.md"),
+			wantErr: false,
+		},
+		{
+			name:    "path in default ~/.claude/plans is rejected when CLAUDE_CONFIG_DIR is set",
+			path:    filepath.Join(os.Getenv("HOME"), ".claude", "plans", "plan.md"),
+			wantErr: true,
+		},
+		{
+			name:    "path traversal still rejected",
+			path:    filepath.Join(plansDir, "..", "..", "etc", "passwd"),
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := validatePlanPath(tt.path)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("validatePlanPath(%q) error = %v, wantErr %v", tt.path, err, tt.wantErr)
+			}
+		})
+	}
+}
+
 func TestValidatePlanPath(t *testing.T) {
 	homeDir, err := os.UserHomeDir()
 	if err != nil {

internal/plugins/plugins.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/zhubert/plural/internal/claudeconfig"
 	"github.com/zhubert/plural/internal/logger"
 )
 
@@ -33,11 +34,11 @@ type Plugin struct {
 
 // getClaudeDir returns the Claude config directory path
 func getClaudeDir() string {
-	home, err := os.UserHomeDir()
+	dir, err := claudeconfig.GetClaudeConfigDir()
 	if err != nil {
 		return ""
 	}
-	return filepath.Join(home, ".claude")
+	return dir
 }
 
 // knownMarketplacesFile is the structure of ~/.claude/plugins/known_marketplaces.json