agent (unreleased): fixes after an independent review — one lock for the writers of agent.json, the trust run serialised and bounded, the CA copy keeps its previous root, the profile stanza from the wrapper's answer, a stale give-up ends, both boot tokens from one read

Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

internal/localapi/backup_target.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"gitea.dooplex.hu/admin/felhom-agent/internal/config"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -148,6 +149,8 @@ func (s *Server) validateBackupTargetMount(ctx context.Context, where string) er
 // agent-owned 0600, so the non-root agent cannot rename into that directory. A recovery copy is
 // parked first, so a torn write is recoverable.
 func (s *Server) setConfiguredBackupTarget(id string) error {
+	config.FileMu.Lock() // one writer of agent.json at a time in this process (config.FileMu)
+	defer config.FileMu.Unlock()
 	path := s.configPath
 	if path == "" {
 		return fmt.Errorf("no config path known to this agent (env-only config)")