feat: add workspace detection by walking up directory tree

Detection:
- Find() walks up from given directory looking for markers
- Primary marker: config/town.json
- Secondary marker: mayor/ directory
- Follows symlinks using filepath.EvalSymlinks

Functions:
- Find, FindOrError: from given directory
- FindFromCwd, FindFromCwdOrError: from current directory
- IsWorkspace: check if directory is workspace root

Closes gt-f9x.2

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/workspace/find_test.go

@@ -0,0 +1,177 @@
+package workspace
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func realPath(t *testing.T, path string) string {
+	t.Helper()
+	real, err := filepath.EvalSymlinks(path)
+	if err != nil {
+		t.Fatalf("realpath: %v", err)
+	}
+	return real
+}
+
+func TestFindWithPrimaryMarker(t *testing.T) {
+	// Create temp workspace structure
+	root := realPath(t, t.TempDir())
+	configDir := filepath.Join(root, "config")
+	if err := os.MkdirAll(configDir, 0755); err != nil {
+		t.Fatalf("mkdir: %v", err)
+	}
+	townFile := filepath.Join(configDir, "town.json")
+	if err := os.WriteFile(townFile, []byte(`{"type":"town"}`), 0644); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+
+	// Create nested directory
+	nested := filepath.Join(root, "some", "deep", "path")
+	if err := os.MkdirAll(nested, 0755); err != nil {
+		t.Fatalf("mkdir nested: %v", err)
+	}
+
+	// Find from nested should return root
+	found, err := Find(nested)
+	if err != nil {
+		t.Fatalf("Find: %v", err)
+	}
+	if found != root {
+		t.Errorf("Find = %q, want %q", found, root)
+	}
+}
+
+func TestFindWithSecondaryMarker(t *testing.T) {
+	// Create temp workspace with just mayor/ directory
+	root := realPath(t, t.TempDir())
+	mayorDir := filepath.Join(root, "mayor")
+	if err := os.MkdirAll(mayorDir, 0755); err != nil {
+		t.Fatalf("mkdir: %v", err)
+	}
+
+	// Create nested directory
+	nested := filepath.Join(root, "rigs", "test")
+	if err := os.MkdirAll(nested, 0755); err != nil {
+		t.Fatalf("mkdir nested: %v", err)
+	}
+
+	// Find from nested should return root
+	found, err := Find(nested)
+	if err != nil {
+		t.Fatalf("Find: %v", err)
+	}
+	if found != root {
+		t.Errorf("Find = %q, want %q", found, root)
+	}
+}
+
+func TestFindNotFound(t *testing.T) {
+	// Create temp dir with no markers
+	dir := t.TempDir()
+
+	found, err := Find(dir)
+	if err != nil {
+		t.Fatalf("Find: %v", err)
+	}
+	if found != "" {
+		t.Errorf("Find = %q, want empty string", found)
+	}
+}
+
+func TestFindOrErrorNotFound(t *testing.T) {
+	dir := t.TempDir()
+
+	_, err := FindOrError(dir)
+	if err != ErrNotFound {
+		t.Errorf("FindOrError = %v, want ErrNotFound", err)
+	}
+}
+
+func TestFindAtRoot(t *testing.T) {
+	// Create workspace at temp root level
+	root := realPath(t, t.TempDir())
+	configDir := filepath.Join(root, "config")
+	if err := os.MkdirAll(configDir, 0755); err != nil {
+		t.Fatalf("mkdir: %v", err)
+	}
+	townFile := filepath.Join(configDir, "town.json")
+	if err := os.WriteFile(townFile, []byte(`{"type":"town"}`), 0644); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+
+	// Find from root should return root
+	found, err := Find(root)
+	if err != nil {
+		t.Fatalf("Find: %v", err)
+	}
+	if found != root {
+		t.Errorf("Find = %q, want %q", found, root)
+	}
+}
+
+func TestIsWorkspace(t *testing.T) {
+	root := t.TempDir()
+
+	// Not a workspace initially
+	is, err := IsWorkspace(root)
+	if err != nil {
+		t.Fatalf("IsWorkspace: %v", err)
+	}
+	if is {
+		t.Error("expected not a workspace initially")
+	}
+
+	// Add primary marker
+	configDir := filepath.Join(root, "config")
+	if err := os.MkdirAll(configDir, 0755); err != nil {
+		t.Fatalf("mkdir: %v", err)
+	}
+	townFile := filepath.Join(configDir, "town.json")
+	if err := os.WriteFile(townFile, []byte(`{"type":"town"}`), 0644); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+
+	// Now is a workspace
+	is, err = IsWorkspace(root)
+	if err != nil {
+		t.Fatalf("IsWorkspace: %v", err)
+	}
+	if !is {
+		t.Error("expected to be a workspace")
+	}
+}
+
+func TestFindFollowsSymlinks(t *testing.T) {
+	// Create workspace
+	root := realPath(t, t.TempDir())
+	configDir := filepath.Join(root, "config")
+	if err := os.MkdirAll(configDir, 0755); err != nil {
+		t.Fatalf("mkdir: %v", err)
+	}
+	townFile := filepath.Join(configDir, "town.json")
+	if err := os.WriteFile(townFile, []byte(`{"type":"town"}`), 0644); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+
+	// Create a symlinked directory
+	linkTarget := filepath.Join(root, "actual")
+	if err := os.MkdirAll(linkTarget, 0755); err != nil {
+		t.Fatalf("mkdir: %v", err)
+	}
+
+	linkName := filepath.Join(root, "linked")
+	if err := os.Symlink(linkTarget, linkName); err != nil {
+		t.Skipf("symlink not supported: %v", err)
+	}
+
+	// Find from symlinked dir should work
+	found, err := Find(linkName)
+	if err != nil {
+		t.Fatalf("Find: %v", err)
+	}
+	if found != root {
+		t.Errorf("Find = %q, want %q", found, root)
+	}
+}