core/mcp
8
0
Fork 0
Code Issues 4 Pull requests 2 Projects Releases Packages Wiki Activity Actions

fix(mcp): snapshot exposed service slices

Browse source 
Return copies from service accessors and ignore nil subsystems during construction to keep the MCP service API stable and AX-friendly.

Co-Authored-By: Virgil <virgil@lethean.io>
This commit is contained in:
Virgil 2026-04-02 14:10:53 +00:00
parent aae824a4d0
commit 2a4e8b7ba3
2 changed files with 31 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

16
pkg/mcp/mcp.go
View file

@ -83,7 +83,6 @@ func New(opts Options) (*Service, error) {
server: server,
processService: opts.ProcessService,
wsHub: opts.WSHub,
subsystems: opts.Subsystems,
logger: log.Default(),
processMeta: make(map[string]processRuntime),
}
@ -115,7 +114,12 @@ func New(opts Options) (*Service, error) {
s.registerTools(s.server)
for _, sub := range s.subsystems {
s.subsystems = make([]Subsystem, 0, len(opts.Subsystems))
for _, sub := range opts.Subsystems {
if sub == nil {
continue
}
s.subsystems = append(s.subsystems, sub)
if sn, ok := sub.(SubsystemWithNotifier); ok {
sn.SetNotifier(s)
}
@ -141,7 +145,7 @@ func New(opts Options) (*Service, error) {
// fmt.Println(sub.Name())
// }
func (s *Service) Subsystems() []Subsystem {
return s.subsystems
return slices.Clone(s.subsystems)
}
// SubsystemsSeq returns an iterator over the registered subsystems.
@ -150,7 +154,7 @@ func (s *Service) Subsystems() []Subsystem {
// fmt.Println(sub.Name())
// }
func (s *Service) SubsystemsSeq() iter.Seq[Subsystem] {
return slices.Values(s.subsystems)
return slices.Values(slices.Clone(s.subsystems))
}
// Tools returns all recorded tool metadata.
@ -159,7 +163,7 @@ func (s *Service) SubsystemsSeq() iter.Seq[Subsystem] {
// fmt.Printf("%s (%s): %s\n", t.Name, t.Group, t.Description)
// }
func (s *Service) Tools() []ToolRecord {
return s.tools
return slices.Clone(s.tools)
}
// ToolsSeq returns an iterator over all recorded tool metadata.
@ -168,7 +172,7 @@ func (s *Service) Tools() []ToolRecord {
// fmt.Println(rec.Name)
// }
func (s *Service) ToolsSeq() iter.Seq[ToolRecord] {
return slices.Values(s.tools)
return slices.Values(slices.Clone(s.tools))
}
// Shutdown gracefully shuts down all subsystems that support it.

21
pkg/mcp/subsystem_test.go
View file

@ -88,6 +88,27 @@ func TestSubsystem_Good_MultipleSubsystems(t *testing.T) {
}
}
func TestSubsystem_Good_NilEntriesIgnoredAndSnapshots(t *testing.T) {
sub := &stubSubsystem{name: "snap-sub"}
svc, err := New(Options{Subsystems: []Subsystem{nil, sub}})
if err != nil {
t.Fatalf("New() failed: %v", err)
}
subs := svc.Subsystems()
if len(subs) != 1 {
t.Fatalf("expected 1 subsystem after filtering nil entries, got %d", len(subs))
}
if subs[0].Name() != "snap-sub" {
t.Fatalf("expected snap-sub, got %q", subs[0].Name())
}
subs[0] = nil
if svc.Subsystems()[0] == nil {
t.Fatal("expected Subsystems() to return a snapshot, not the live slice")
}
}
func TestSubsystem_Good_NotifierSetBeforeRegistration(t *testing.T) {
sub := &notifierSubsystem{stubSubsystem: stubSubsystem{name: "notifier-sub"}}
_, err := New(Options{Subsystems: []Subsystem{sub}})