add black-box debug harness

internal/harness/recorder.go

@@ -0,0 +1,52 @@
+package harness
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+type Artifact struct {
+	Dir string `json:"artifact_dir"`
+}
+
+func (s *Session) DumpArtifacts(sc *Scenario, failingStep int, cause error) (*Artifact, error) {
+	name := sc.Name
+	if name == "" {
+		name = strings.TrimSuffix(filepath.Base(sc.Path), filepath.Ext(sc.Path))
+	}
+	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 {
+		return nil, err
+	}
+	screen, _ := s.em.ScreenText()
+	_ = os.WriteFile(filepath.Join(abs, "grid.log"), []byte(screen), 0o600)
+	_ = os.WriteFile(filepath.Join(abs, "raw.bytes"), s.rawBytes(), 0o600)
+	if b, err := s.em.SerializeVT(); err == nil {
+		_ = os.WriteFile(filepath.Join(abs, "serialize.vt"), b, 0o600)
+	}
+	envBytes, _ := json.MarshalIndent(s.env, "", "  ")
+	_ = os.WriteFile(filepath.Join(abs, "env.json"), append(envBytes, '\n'), 0o600)
+	annotated := map[string]any{"scenario": sc, "failing_step": failingStep}
+	if cause != nil {
+		annotated["error"] = cause.Error()
+	}
+	ab, _ := json.MarshalIndent(annotated, "", "  ")
+	_ = os.WriteFile(filepath.Join(abs, "scenario.annotated.json"), append(ab, '\n'), 0o600)
+	snapshot := map[string]json.RawMessage{}
+	for _, method := range []string{"whoami", "list_processes", "get_project_status"} {
+		if raw, err := s.mcp.Call(method, map[string]any{}); err == nil {
+			snapshot[method] = raw
+		}
+	}
+	sb, _ := json.MarshalIndent(snapshot, "", "  ")
+	_ = os.WriteFile(filepath.Join(abs, "mcp-snapshot.json"), append(sb, '\n'), 0o600)
+	return &Artifact{Dir: abs}, nil
+}