Derive stable prompt sessions for CLI runs

internal/framework/pipeline/runner_session_test.go

@@ -0,0 +1,37 @@
+package pipeline
+
+import (
+	"context"
+	"testing"
+)
+
+func TestRunnerUsesProvidedSessionWithoutSourceFallback(t *testing.T) {
+	for _, test := range []struct {
+		name    string
+		session string
+		wantSet bool
+		want    string
+	}{
+		{name: "provided", session: " supplied-session ", wantSet: true, want: "supplied-session"},
+		{name: "empty", wantSet: false},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			prepared, _ := preparedTerminalDebugPipeline(t)
+			output, err := New().Run(context.Background(), RunInput{
+				Prepared:  prepared,
+				RawInput:  []byte("input"),
+				SessionID: test.session,
+			})
+			if err != nil {
+				t.Fatal(err)
+			}
+			value, found := output.Manifest.Metadata["session_id"]
+			if found != test.wantSet {
+				t.Fatalf("manifest session presence = %t, want %t; metadata = %#v", found, test.wantSet, output.Manifest.Metadata)
+			}
+			if found && value != test.want {
+				t.Fatalf("manifest session = %#v, want %q", value, test.want)
+			}
+		})
+	}
+}