feat: field-sync-gui MVP — Wails GUI ingest SD→local+S3 (4 slots //)

internal/manifest/manifest.go

@@ -0,0 +1,67 @@
+package manifest
+
+import (
+	"encoding/json"
+	"os"
+	"sync"
+)
+
+// Entry is one copied file record
+type Entry struct {
+	Source    string `json:"source"`
+	LocalDest string `json:"localDest"`
+	S3Path    string `json:"s3Path,omitempty"`
+	SHA256    string `json:"sha256"`
+	Bytes     int64  `json:"bytes"`
+	Status    string `json:"status"` // "local" | "s3" | "done" | "error"
+	Error     string `json:"error,omitempty"`
+}
+
+// Manifest holds all entries for a session
+type Manifest struct {
+	SessionID string  `json:"sessionID"`
+	Entries   []Entry `json:"entries"`
+	mu        sync.Mutex
+}
+
+// New creates a new manifest
+func New(sessionID string) *Manifest {
+	return &Manifest{SessionID: sessionID}
+}
+
+// Append adds an entry atomically
+func (m *Manifest) Append(e Entry) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	m.Entries = append(m.Entries, e)
+}
+
+// Save writes manifest atomically via temp file + rename
+func (m *Manifest) Save(path string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	data, err := json.MarshalIndent(m, "", "  ")
+	if err != nil {
+		return err
+	}
+
+	tmp := path + ".tmp"
+	if err := os.WriteFile(tmp, data, 0644); err != nil {
+		return err
+	}
+	return os.Rename(tmp, path)
+}
+
+// Load reads a manifest from disk
+func Load(path string) (*Manifest, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	var m Manifest
+	if err := json.Unmarshal(data, &m); err != nil {
+		return nil, err
+	}
+	return &m, nil
+}