feat: storage writes via storage-agent, accepts_uploads and write_template (M5.5)

- storage-agent: POST /internal/files copies a staged file into a source
  (temp file, fsync, SHA-256 check, hard link so nothing is overwritten,
  " (2)" suffix on conflict, owner PIPU_FILE_UID/GID) and
  POST /internal/files/test. NFS sources that accept uploads are mounted
  rw in an agent-only /library-rw and bind-mounted read-only for others;
  local sources are written through /library-host-rw.
- meta: write templates ({track:02}, {disc:1-}, [optional]) with name
  sanitising and length limits, suggestion from the source's regexes
  and a reversibility check against 50 catalogue tracks.
- API and admin UI: accepts_uploads / write_template on sources,
  write-template suggest and check endpoints, write test result.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

services/api/internal/library/service.go

@@ -35,6 +35,8 @@ const (
 	CodeNameInvalid      = "validation.name_invalid"
 	CodeIntervalInvalid  = "validation.scan_interval_invalid"
 	CodeNotFound         = "catalog.not_found"
+	CodeTemplateInvalid  = "validation.template_invalid"
+	CodeTemplateNone     = "library.template_unavailable"
 )
 
 // Config — пути к хранилищам в файловой системе api.
@@ -139,6 +141,8 @@ type SourceInput struct {
 	TagsFirst           *bool
 	ScanIntervalMinutes *int // 0 — выключить
 	Enabled             *bool
+	AcceptsUploads      *bool
+	WriteTemplate       *string // "" — убрать
 }
 
 func (s *Service) apply(src *Source, in SourceInput) error {
@@ -164,6 +168,21 @@ func (s *Service) apply(src *Source, in SourceInput) error {
 			src.ScanInterval = &d
 		}
 	}
+	if in.AcceptsUploads != nil {
+		src.AcceptsUploads = *in.AcceptsUploads
+	}
+	if in.WriteTemplate != nil {
+		if strings.TrimSpace(*in.WriteTemplate) == "" {
+			src.WriteTemplate = nil
+		} else {
+			tpl, err := meta.ParseTemplate(*in.WriteTemplate)
+			if err != nil {
+				return apperr.Validation("write_template", CodeTemplateInvalid, err.Error(), map[string]any{"reason": err.Error()})
+			}
+			text := tpl.String()
+			src.WriteTemplate = &text
+		}
+	}
 	switch src.Type {
 	case SourceLocal:
 		if in.LocalPath != nil {
@@ -251,7 +270,8 @@ func (s *Service) UpdateSource(ctx context.Context, id uuid.UUID, in SourceInput
 		return Source{}, err
 	}
 	location := func(x Source) string {
-		return fmt.Sprint(x.LocalPath != nil && *x.LocalPath != "", deref(x.LocalPath), deref(x.NFSServer), deref(x.NFSExport), x.NFSOptions)
+		return fmt.Sprint(x.LocalPath != nil && *x.LocalPath != "", deref(x.LocalPath), deref(x.NFSServer), deref(x.NFSExport), x.NFSOptions,
+			x.Type == SourceNFS && x.AcceptsUploads)
 	}
 	switch {
 	case in.Enabled != nil && !*in.Enabled:
@@ -308,7 +328,7 @@ func (s *Service) check(ctx context.Context, src Source, mount bool) (string, *s
 			}
 			return "mounted", nil
 		}
-		res, err := s.agent.Mount(ctx, src.ID, nfsSpec(src))
+		res, err := s.agent.Mount(ctx, src.ID, nfsSpec(src), src.AcceptsUploads)
 		if err != nil {
 			return "error", msg(err.Error())
 		}
@@ -354,6 +374,17 @@ type TestResult struct {
 	OK         bool
 	Message    string
 	AudioFiles int
+	Write      *storageagent.WriteTestResult // только для accepts_uploads
+}
+
+// writeTarget — как агенту найти источник на запись.
+func writeTarget(src Source) storageagent.WriteTestRequest {
+	req := storageagent.WriteTestRequest{SourceID: src.ID.String()}
+	if src.Type == SourceLocal {
+		lp := deref(src.LocalPath)
+		req.LocalPath = &lp
+	}
+	return req
 }
 
 // TestSource проверяет доступ к хранилищу и считает аудиофайлы (до 1000).
@@ -365,6 +396,19 @@ func (s *Service) TestSource(ctx context.Context, id uuid.UUID) (TestResult, err
 	if err != nil {
 		return TestResult{}, notFound(err)
 	}
+	res, err := s.testRead(ctx, src)
+	if err != nil || !src.AcceptsUploads {
+		return res, err
+	}
+	w, err := s.agent.TestWrite(ctx, writeTarget(src))
+	if err != nil {
+		w = storageagent.WriteTestResult{Message: err.Error()}
+	}
+	res.Write = &w
+	return res, nil
+}
+
+func (s *Service) testRead(ctx context.Context, src Source) (TestResult, error) {
 	if src.Type == SourceNFS {
 		res, err := s.agent.Test(ctx, nfsSpec(src))
 		if err != nil {
@@ -715,3 +759,62 @@ func (s *Service) healthCheck(ctx context.Context, src Source) {
 		}
 	}
 }
+
+// templateSampleSize — сколько треков берёт проверка шаблона записи (docs/uploads.md#7).
+const templateSampleSize = 50
+
+// SuggestWriteTemplate подбирает шаблон записи по существующим путям и выражениям источника.
+func (s *Service) SuggestWriteTemplate(ctx context.Context, id uuid.UUID) (string, error) {
+	if err := requirePerm(ctx, auth.PermManageLibrary); err != nil {
+		return "", err
+	}
+	if _, err := s.store.GetSource(ctx, id); err != nil {
+		return "", notFound(err)
+	}
+	rows, err := s.store.Patterns(ctx, id)
+	if err != nil {
+		return "", err
+	}
+	var exprs []string
+	for _, r := range rows {
+		if r.IsEnabled {
+			exprs = append(exprs, r.Regex)
+		}
+	}
+	paths, err := s.store.SampleFiles(ctx, id, 200)
+	if err != nil {
+		return "", err
+	}
+	tpl, err := meta.SuggestTemplate(exprs, paths)
+	if err != nil {
+		return "", apperr.New(http.StatusUnprocessableEntity, CodeTemplateNone, "no path pattern can be turned into a template")
+	}
+	return tpl, nil
+}
+
+// CheckWriteTemplate применяет шаблон к трекам источника и разбирает пути его выражениями обратно.
+func (s *Service) CheckWriteTemplate(ctx context.Context, id uuid.UUID, template string) (meta.TemplateCheck, error) {
+	if err := requirePerm(ctx, auth.PermManageLibrary); err != nil {
+		return meta.TemplateCheck{}, err
+	}
+	if _, err := s.store.GetSource(ctx, id); err != nil {
+		return meta.TemplateCheck{}, notFound(err)
+	}
+	tpl, err := meta.ParseTemplate(template)
+	if err != nil {
+		return meta.TemplateCheck{}, apperr.Validation("template", CodeTemplateInvalid, err.Error(), map[string]any{"reason": err.Error()})
+	}
+	rows, err := s.store.Patterns(ctx, id)
+	if err != nil {
+		return meta.TemplateCheck{}, err
+	}
+	compiled, err := compile(rows)
+	if err != nil {
+		return meta.TemplateCheck{}, err
+	}
+	samples, err := s.store.TemplateSamples(ctx, id, templateSampleSize)
+	if err != nil {
+		return meta.TemplateCheck{}, err
+	}
+	return meta.CheckTemplate(tpl, compiled, samples), nil
+}