Serve print, JSON, and RPC modes on AgentSession

Why: The library had no process entry, and the product backend still called the loop directly.
Evidence: go test -count=1 ./...
Impact: exec.Backend keeps the same request and result. Execute now goes through AgentSession. Extensions and packages are not a sandbox.
Refs: feature/pi-headless N6 N7
Co-authored-by: Cursor <cursoragent@cursor.com>

adapters/native/backend.go

@@ -319,7 +319,7 @@ func (b *Backend) run(ctx context.Context, model string, budget *runtime.Budget,
 	if strings.TrimSpace(execID) == "" {
 		execID = b.opts.ExecutionID
 	}
-	runRes, err := runtime.Run(ctx, runtime.Config{
+	agent := runtime.NewAgentSession(runtime.Config{
 		Model:        model,
 		SystemPrompt: b.systemPrompt(req, model, profile, workDir, skillIndex),
 		Tools:        reg,
@@ -351,8 +351,8 @@ func (b *Backend) run(ctx context.Context, model string, budget *runtime.Budget,
 				})
 			}
 		},
-	}, llm.Message{Role: llm.RoleUser, Content: req.Prompt})
-	return runRes, err
+	})
+	return agent.Prompt(ctx, llm.Message{Role: llm.RoleUser, Content: req.Prompt})
 }
 
 // maybeCompact 在转录超过阈值时压缩头部历史。压缩是优化性质：

adapters/native/compact_test.go

@@ -47,8 +47,11 @@ func TestBackendCompactBeforeRun(t *testing.T) {
 		t.Fatal("compaction should have run before the loop")
 	}
 	data, _ := os.ReadFile(transcript)
-	if !strings.Contains(string(data), "[conversation summary]") {
-		t.Fatalf("transcript should contain the summary marker, got:\n%.200s", data)
+	if !strings.Contains(string(data), "预置历史摘要") || !strings.Contains(string(data), `"type":"compaction"`) {
+		t.Fatalf("transcript should keep history and append a compaction entry, got:\n%.400s", data)
+	}
+	if !strings.Contains(string(data), `"role":"system"`) {
+		t.Fatal("compaction must not rewrite the original transcript")
 	}
 }
 

adapters/native/pi_conformance_test.go

@@ -0,0 +1,65 @@
+package native
+
+import (
+	"context"
+	"encoding/json"
+	"os"
+	"os/exec"
+	"testing"
+
+	"agent-native/rpc"
+	"agent-native/runtime"
+	"agent-native/runtime/llm"
+	"agent-native/runtime/session"
+)
+
+func TestEventAndRPCFixtures(t *testing.T) {
+	var types []string
+	agent := runtime.NewAgentSession(runtime.Config{
+		Model: "fake",
+		Stream: func(ctx context.Context, model string, messages []llm.Message, td []llm.ToolDecl, opts llm.StreamOptions) <-chan llm.Event {
+			ch := make(chan llm.Event, 1)
+			ch <- llm.Event{Kind: llm.KindMessageEnd, Message: llm.Message{Role: llm.RoleAssistant, Content: "ok", StopReason: llm.StopEnd}}
+			close(ch)
+			return ch
+		},
+		OnEvent: func(ev runtime.Event) { types = append(types, ev.Type) },
+	})
+	if _, err := agent.Prompt(context.Background(), llm.Message{Role: llm.RoleUser, Content: "hi"}); err != nil {
+		t.Fatal(err)
+	}
+	raw, _ := json.Marshal(types)
+	for _, want := range []string{"message_start", "message_end", "agent_settled"} {
+		if !contains(types, want) {
+			t.Fatalf("fixture missing %s in %s", want, raw)
+		}
+	}
+	dir := t.TempDir()
+	store, err := session.Open(dir + "/s.jsonl")
+	if err != nil {
+		t.Fatal(err)
+	}
+	srv := &rpc.Server{Agent: agent, Store: store}
+	resp, err := srv.Handle(context.Background(), []byte(`{"type":"get_session_stats"}`))
+	if err != nil || !json.Valid(resp) {
+		t.Fatalf("rpc fixture: %s %v", resp, err)
+	}
+}
+
+func TestPiCrossCompareOptional(t *testing.T) {
+	if _, err := exec.LookPath("pi"); err != nil {
+		t.Skip("pi is not installed")
+	}
+	if os.Getenv("PI_CROSS") != "1" {
+		t.Skip("set PI_CROSS=1 to compare a live pi process")
+	}
+}
+
+func contains(list []string, want string) bool {
+	for _, item := range list {
+		if item == want {
+			return true
+		}
+	}
+	return false
+}