Simplify session lifecycle and MCP cleanup

internal/harness/env.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"strings"
+	"sync"
 
 	"github.com/hjbdev/patterm/internal/projectkey"
 	"github.com/hjbdev/patterm/internal/trust"
@@ -179,9 +180,18 @@ func defaultPattermBin() (string, error) {
 	if p := os.Getenv("PATTERM_BIN"); p != "" {
 		return p, nil
 	}
-	return buildPattermBinary()
+	defaultBinOnce.Do(func() {
+		defaultBinPath, defaultBinErr = buildPattermBinary()
+	})
+	return defaultBinPath, defaultBinErr
 }
 
+var (
+	defaultBinOnce sync.Once
+	defaultBinPath string
+	defaultBinErr  error
+)
+
 func buildPattermBinary() (string, error) {
 	root, err := repoRoot()
 	if err != nil {

internal/harness/recorder.go

@@ -21,9 +21,16 @@ func (s *Session) DumpArtifacts(sc *Scenario, failingStep int, cause error) (*Ar
 	if name == "" {
 		name = "scenario"
 	}
-	dir := filepath.Join("internal", "harness", ".artifacts", fmt.Sprintf("%s-%d", name, time.Now().Unix()))
-	abs, _ := filepath.Abs(dir)
-	if err := os.MkdirAll(abs, 0o700); err != nil {
+	root, err := repoRoot()
+	if err != nil {
+		return nil, err
+	}
+	base := filepath.Join(root, "internal", "harness", ".artifacts")
+	if err := os.MkdirAll(base, 0o700); err != nil {
+		return nil, err
+	}
+	abs, err := os.MkdirTemp(base, fmt.Sprintf("%s-%d-*", name, time.Now().UnixNano()))
+	if err != nil {
 		return nil, err
 	}
 	screen, _ := s.em.ScreenText()

internal/harness/session.go

@@ -210,19 +210,19 @@ func (s *Session) WaitForStable(timeout time.Duration) error {
 }
 
 func (s *Session) WaitForText(text string, timeout time.Duration) error {
-	deadline := time.Now().Add(timeout)
-	for time.Now().Before(deadline) {
+	return pollUntil(timeout, 25*time.Millisecond, func() (bool, error) {
 		screen, err := s.Screen()
 		if err != nil {
-			return err
+			return false, err
 		}
 		if strings.Contains(screen, text) {
-			return nil
+			return true, nil
 		}
-		time.Sleep(25 * time.Millisecond)
-	}
-	screen, _ := s.Screen()
-	return fmt.Errorf("text %q not found before timeout; screen:\n%s", text, screen)
+		return false, nil
+	}, func() error {
+		screen, _ := s.Screen()
+		return fmt.Errorf("text %q not found before timeout; screen:\n%s", text, screen)
+	})
 }
 
 func (s *Session) WaitForRegex(pattern string, timeout time.Duration) error {
@@ -230,19 +230,31 @@ func (s *Session) WaitForRegex(pattern string, timeout time.Duration) error {
 	if err != nil {
 		return err
 	}
-	deadline := time.Now().Add(timeout)
-	for time.Now().Before(deadline) {
+	return pollUntil(timeout, 25*time.Millisecond, func() (bool, error) {
 		screen, err := s.Screen()
 		if err != nil {
-			return err
+			return false, err
 		}
 		if re.MatchString(screen) {
-			return nil
+			return true, nil
 		}
-		time.Sleep(25 * time.Millisecond)
+		return false, nil
+	}, func() error {
+		screen, _ := s.Screen()
+		return fmt.Errorf("regex %q not found before timeout; screen:\n%s", pattern, screen)
+	})
+}
+
+func pollUntil(timeout, interval time.Duration, check func() (bool, error), timeoutErr func() error) error {
+	deadline := time.Now().Add(timeout)
+	for time.Now().Before(deadline) {
+		ok, err := check()
+		if err != nil || ok {
+			return err
+		}
+		time.Sleep(interval)
 	}
-	screen, _ := s.Screen()
-	return fmt.Errorf("regex %q not found before timeout; screen:\n%s", pattern, screen)
+	return timeoutErr()
 }
 
 func (s *Session) MCPCall(method string, params json.RawMessage) (json.RawMessage, error) {