agent: add exec event role for ! command output

Shell command output uses a dedicated "exec" role instead of "info",
formatted with ``` fences in the chat log.

pkg/agent/commands.go

@@ -33,7 +33,7 @@ func (s *agent) handleCommand(ctx context.Context, input string) bool {
 			s.emit(infoEvent("error: " + err.Error()))
 		}
 		if len(o) > 0 {
-			s.emit(infoEvent(strings.TrimRight(string(o), "\n")))
+			s.emit(execEvent(strings.TrimRight(string(o), "\n")))
 		}
 		return true
 	}

pkg/agent/core.go

@@ -223,6 +223,10 @@ func infoEvent(text string) Event {
 	return Event{Role: "info", Content: text + "\n"}
 }
 
+func execEvent(text string) Event {
+	return Event{Role: "exec", Content: text}
+}
+
 // actionHandle holds the cancel function for the current agent turn.
 type actionHandle struct {
 	cancel context.CancelCauseFunc

pkg/agent/core_test.go

@@ -648,13 +648,13 @@ func TestShellCommand_Basic(t *testing.T) {
 	c := newCore(t, nil, nil)
 	evs := collectEvents(context.Background(), c, "!echo shellout")
 	found := false
-	for _, s := range byRole(evs, "info") {
+	for _, s := range byRole(evs, "exec") {
 		if strings.Contains(s, "shellout") {
 			found = true
 		}
 	}
 	if !found {
-		t.Errorf("!echo shellout: output not in info events: %v", byRole(evs, "info"))
+		t.Errorf("!echo shellout: output not in exec events: %v", byRole(evs, "exec"))
 	}
 	if c.IsRunning() {
 		t.Error("IsRunning() = true after shell command; want false")
@@ -2227,15 +2227,15 @@ func TestSetEnv_ShellCommandSeesEnv(t *testing.T) {
 	c.SetEnv("OLLIE_TEST_VAR", "sentinel_value")
 
 	evs := collectEvents(context.Background(), c, "!echo $OLLIE_TEST_VAR")
-	infos := byRole(evs, "info")
+	execs := byRole(evs, "exec")
 	found := false
-	for _, s := range infos {
+	for _, s := range execs {
 		if strings.Contains(s, "sentinel_value") {
 			found = true
 		}
 	}
 	if !found {
-		t.Errorf("shell command did not see OLLIE_TEST_VAR; info events: %v", infos)
+		t.Errorf("shell command did not see OLLIE_TEST_VAR; exec events: %v", execs)
 	}
 }