feat: file explorer

backend/cmd/server/main.go

@@ -123,6 +123,7 @@ func main() {
 		db.CategoryRepo,
 		db.FeatureFlagRepo,
 		permissionService,
+		encryptor,
 	)
 
 	if err := permissionService.EnsureAdminGroup(context.Background()); err != nil {
@@ -147,6 +148,8 @@ func main() {
 	adminHandler := handlers.NewAdminHandler(adminService)
 	publicHandler := handlers.NewPublicHandler(spaceService, noteService)
 	settingsHandler := handlers.NewSettingsHandler(authService)
+	fileService := services.NewFileService(db.FeatureFlagRepo, db.MembershipRepo, encryptor)
+	fileHandler := handlers.NewFileHandler(fileService)
 
 	// Create router
 	router := mux.NewRouter()
@@ -210,6 +213,14 @@ func main() {
 	api.HandleFunc("/spaces/{spaceId}/categories/{categoryId}", categoryHandler.DeleteCategory).Methods("DELETE")
 	api.HandleFunc("/spaces/{spaceId}/categories/{categoryId}/move", categoryHandler.MoveCategory).Methods("PATCH")
 
+	// File explorer endpoints (space-scoped)
+	api.HandleFunc("/spaces/{spaceId}/files/list", fileHandler.ListFiles).Methods("GET")
+	api.HandleFunc("/spaces/{spaceId}/files/object", fileHandler.GetFile).Methods("GET")
+	api.HandleFunc("/spaces/{spaceId}/files/upload", fileHandler.UploadFile).Methods("POST")
+	api.HandleFunc("/spaces/{spaceId}/files/folder", fileHandler.CreateFolder).Methods("POST")
+	api.HandleFunc("/spaces/{spaceId}/files/object", fileHandler.DeleteFile).Methods("DELETE")
+	api.HandleFunc("/spaces/{spaceId}/files/folder", fileHandler.DeleteFolder).Methods("DELETE")
+
 	// Admin endpoints
 	admin := router.PathPrefix("/api/v1/admin").Subrouter()
 	admin.Use(authMiddleware.Middleware)

backend/go.mod

@@ -12,6 +12,18 @@ require (
 )
 
 require (
+	github.com/aws/aws-sdk-go-v2 v1.41.4 // indirect
+	github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.8 // indirect
+	github.com/aws/aws-sdk-go-v2/credentials v1.19.12 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/configsources v1.4.20 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.7.20 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/v4a v1.4.21 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.13.7 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/checksum v1.9.12 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.13.20 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.19.20 // indirect
+	github.com/aws/aws-sdk-go-v2/service/s3 v1.97.2 // indirect
+	github.com/aws/smithy-go v1.24.2 // indirect
 	github.com/klauspost/compress v1.17.6 // indirect
 	github.com/xdg-go/pbkdf2 v1.0.0 // indirect
 	github.com/xdg-go/scram v1.2.0 // indirect

backend/go.sum

@@ -1,3 +1,27 @@
+github.com/aws/aws-sdk-go-v2 v1.41.4 h1:10f50G7WyU02T56ox1wWXq+zTX9I1zxG46HYuG1hH/k=
+github.com/aws/aws-sdk-go-v2 v1.41.4/go.mod h1:mwsPRE8ceUUpiTgF7QmQIJ7lgsKUPQOUl3o72QBrE1o=
+github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.8 h1:eBMB84YGghSocM7PsjmmPffTa+1FBUeNvGvFou6V/4o=
+github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.7.8/go.mod h1:lyw7GFp3qENLh7kwzf7iMzAxDn+NzjXEAGjKS2UOKqI=
+github.com/aws/aws-sdk-go-v2/credentials v1.19.12 h1:oqtA6v+y5fZg//tcTWahyN9PEn5eDU/Wpvc2+kJ4aY8=
+github.com/aws/aws-sdk-go-v2/credentials v1.19.12/go.mod h1:U3R1RtSHx6NB0DvEQFGyf/0sbrpJrluENHdPy1j/3TE=
+github.com/aws/aws-sdk-go-v2/internal/configsources v1.4.20 h1:CNXO7mvgThFGqOFgbNAP2nol2qAWBOGfqR/7tQlvLmc=
+github.com/aws/aws-sdk-go-v2/internal/configsources v1.4.20/go.mod h1:oydPDJKcfMhgfcgBUZaG+toBbwy8yPWubJXBVERtI4o=
+github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.7.20 h1:tN6W/hg+pkM+tf9XDkWUbDEjGLb+raoBMFsTodcoYKw=
+github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.7.20/go.mod h1:YJ898MhD067hSHA6xYCx5ts/jEd8BSOLtQDL3iZsvbc=
+github.com/aws/aws-sdk-go-v2/internal/v4a v1.4.21 h1:SwGMTMLIlvDNyhMteQ6r8IJSBPlRdXX5d4idhIGbkXA=
+github.com/aws/aws-sdk-go-v2/internal/v4a v1.4.21/go.mod h1:UUxgWxofmOdAMuqEsSppbDtGKLfR04HGsD0HXzvhI1k=
+github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.13.7 h1:5EniKhLZe4xzL7a+fU3C2tfUN4nWIqlLesfrjkuPFTY=
+github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.13.7/go.mod h1:x0nZssQ3qZSnIcePWLvcoFisRXJzcTVvYpAAdYX8+GI=
+github.com/aws/aws-sdk-go-v2/service/internal/checksum v1.9.12 h1:qtJZ70afD3ISKWnoX3xB0J2otEqu3LqicRcDBqsj0hQ=
+github.com/aws/aws-sdk-go-v2/service/internal/checksum v1.9.12/go.mod h1:v2pNpJbRNl4vEUWEh5ytQok0zACAKfdmKS51Hotc3pQ=
+github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.13.20 h1:2HvVAIq+YqgGotK6EkMf+KIEqTISmTYh5zLpYyeTo1Y=
+github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.13.20/go.mod h1:V4X406Y666khGa8ghKmphma/7C0DAtEQYhkq9z4vpbk=
+github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.19.20 h1:siU1A6xjUZ2N8zjTHSXFhB9L/2OY8Dqs0xXiLjF30jA=
+github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.19.20/go.mod h1:4TLZCmVJDM3FOu5P5TJP0zOlu9zWgDWU7aUxWbr+rcw=
+github.com/aws/aws-sdk-go-v2/service/s3 v1.97.2 h1:MRNiP6nqa20aEl8fQ6PJpEq11b2d40b16sm4WD7QgMU=
+github.com/aws/aws-sdk-go-v2/service/s3 v1.97.2/go.mod h1:FrNA56srbsr3WShiaelyWYEo70x80mXnVZ17ZZfbeqg=
+github.com/aws/smithy-go v1.24.2 h1:FzA3bu/nt/vDvmnkg+R8Xl46gmzEDam6mZ1hzmwXFng=
+github.com/aws/smithy-go v1.24.2/go.mod h1:YE2RhdIuDbA5E5bTdciG9KrW3+TiEONeUWCqxX9i1Fc=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/golang-jwt/jwt/v5 v5.2.0 h1:d/ix8ftRUorsN+5eMIlF4T6J8CAt9rch3My2winC1Jw=

backend/internal/application/dto/dto.go

@@ -59,16 +59,28 @@ type CreateAuthProviderRequest struct {
 
 // FeatureFlagsDTO represents app-wide feature flags in API responses.
 type FeatureFlagsDTO struct {
-	RegistrationEnabled  bool `json:"registration_enabled"`
+	RegistrationEnabled  bool   `json:"registration_enabled"`
-	ProviderLoginEnabled bool `json:"provider_login_enabled"`
+	ProviderLoginEnabled bool   `json:"provider_login_enabled"`
-	PublicSharingEnabled bool `json:"public_sharing_enabled"`
+	PublicSharingEnabled bool   `json:"public_sharing_enabled"`
+	FileExplorerEnabled  bool   `json:"file_explorer_enabled"`
+	S3Endpoint           string `json:"s3_endpoint,omitempty"`
+	S3Bucket             string `json:"s3_bucket,omitempty"`
+	S3Region             string `json:"s3_region,omitempty"`
+	S3AccessKey          string `json:"s3_access_key,omitempty"`
+	S3SecretKeySet       bool   `json:"s3_secret_key_set"`
 }
 
 // UpdateFeatureFlagsRequest represents admin payload for feature flag updates.
 type UpdateFeatureFlagsRequest struct {
-	RegistrationEnabled  bool `json:"registration_enabled"`
+	RegistrationEnabled  bool   `json:"registration_enabled"`
-	ProviderLoginEnabled bool `json:"provider_login_enabled"`
+	ProviderLoginEnabled bool   `json:"provider_login_enabled"`
-	PublicSharingEnabled bool `json:"public_sharing_enabled"`
+	PublicSharingEnabled bool   `json:"public_sharing_enabled"`
+	FileExplorerEnabled  bool   `json:"file_explorer_enabled"`
+	S3Endpoint           string `json:"s3_endpoint"`
+	S3Bucket             string `json:"s3_bucket"`
+	S3Region             string `json:"s3_region"`
+	S3AccessKey          string `json:"s3_access_key"`
+	S3SecretKey          string `json:"s3_secret_key"` // empty = keep existing encrypted value
 }
 
 // UserDTO represents a user in API responses
@@ -206,6 +218,12 @@ func NewFeatureFlagsDTO(flags *entities.FeatureFlags) *FeatureFlagsDTO {
 		RegistrationEnabled:  flags.RegistrationEnabled,
 		ProviderLoginEnabled: flags.ProviderLoginEnabled,
 		PublicSharingEnabled: flags.PublicSharingEnabled,
+		FileExplorerEnabled:  flags.FileExplorerEnabled,
+		S3Endpoint:           flags.S3Endpoint,
+		S3Bucket:             flags.S3Bucket,
+		S3Region:             flags.S3Region,
+		S3AccessKey:          flags.S3AccessKey,
+		S3SecretKeySet:       flags.S3SecretKey != "",
 	}
 }
 

backend/internal/application/services/admin_service.go

@@ -10,6 +10,7 @@ import (
 	"github.com/noteapp/backend/internal/application/dto"
 	"github.com/noteapp/backend/internal/domain/entities"
 	"github.com/noteapp/backend/internal/domain/repositories"
+	"github.com/noteapp/backend/internal/infrastructure/security"
 )
 
 // AdminService handles admin-level operations
@@ -22,6 +23,7 @@ type AdminService struct {
 	categoryRepo      repositories.CategoryRepository
 	featureFlagRepo   repositories.FeatureFlagRepository
 	permissionService *PermissionService
+	encryptor         *security.Encryptor
 }
 
 // NewAdminService creates a new AdminService
@@ -34,6 +36,7 @@ func NewAdminService(
 	categoryRepo repositories.CategoryRepository,
 	featureFlagRepo repositories.FeatureFlagRepository,
 	permissionService *PermissionService,
+	encryptor *security.Encryptor,
 ) *AdminService {
 	return &AdminService{
 		userRepo:          userRepo,
@@ -44,6 +47,7 @@ func NewAdminService(
 		categoryRepo:      categoryRepo,
 		featureFlagRepo:   featureFlagRepo,
 		permissionService: permissionService,
+		encryptor:         encryptor,
 	}
 }
 
@@ -299,10 +303,31 @@ func (s *AdminService) UpdateFeatureFlags(ctx context.Context, req *dto.UpdateFe
 		return nil, errors.New("feature flags are unavailable")
 	}
 
+	// Load existing flags so we can preserve the encrypted S3 secret when not updated
+	existing, err := s.featureFlagRepo.GetFeatureFlags(ctx)
+	if err != nil {
+		existing = entities.NewDefaultFeatureFlags()
+	}
+
 	flags := &entities.FeatureFlags{
 		RegistrationEnabled:  req.RegistrationEnabled,
 		ProviderLoginEnabled: req.ProviderLoginEnabled,
 		PublicSharingEnabled: req.PublicSharingEnabled,
+		FileExplorerEnabled:  req.FileExplorerEnabled,
+		S3Endpoint:           strings.TrimSpace(req.S3Endpoint),
+		S3Bucket:             strings.TrimSpace(req.S3Bucket),
+		S3Region:             strings.TrimSpace(req.S3Region),
+		S3AccessKey:          strings.TrimSpace(req.S3AccessKey),
+		S3SecretKey:          existing.S3SecretKey, // keep encrypted secret by default
+	}
+
+	// Only re-encrypt if a new secret was supplied
+	if s.encryptor != nil && strings.TrimSpace(req.S3SecretKey) != "" {
+		encrypted, err := s.encryptor.Encrypt(strings.TrimSpace(req.S3SecretKey))
+		if err != nil {
+			return nil, err
+		}
+		flags.S3SecretKey = encrypted
 	}
 
 	if err := s.featureFlagRepo.UpdateFeatureFlags(ctx, flags); err != nil {

backend/internal/application/services/file_service.go

@@ -0,0 +1,389 @@
+package services
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"io"
+	"path"
+	"strings"
+	"time"
+
+	"github.com/aws/aws-sdk-go-v2/aws"
+	"github.com/aws/aws-sdk-go-v2/credentials"
+	"github.com/aws/aws-sdk-go-v2/service/s3"
+	"github.com/aws/aws-sdk-go-v2/service/s3/types"
+	"go.mongodb.org/mongo-driver/v2/bson"
+
+	"github.com/noteapp/backend/internal/domain/repositories"
+	"github.com/noteapp/backend/internal/infrastructure/security"
+)
+
+// S3Object represents a file or folder entry with key relative to the space root.
+type S3Object struct {
+	Key          string `json:"key"`
+	Size         int64  `json:"size"`
+	LastModified string `json:"last_modified"`
+	IsFolder     bool   `json:"is_folder"`
+}
+
+// FileService handles S3 file operations scoped to individual spaces.
+type FileService struct {
+	featureFlagRepo repositories.FeatureFlagRepository
+	membershipRepo  repositories.MembershipRepository
+	encryptor       *security.Encryptor
+}
+
+// NewFileService creates a new FileService.
+func NewFileService(
+	featureFlagRepo repositories.FeatureFlagRepository,
+	membershipRepo repositories.MembershipRepository,
+	encryptor *security.Encryptor,
+) *FileService {
+	return &FileService{
+		featureFlagRepo: featureFlagRepo,
+		membershipRepo:  membershipRepo,
+		encryptor:       encryptor,
+	}
+}
+
+type s3Config struct {
+	client *s3.Client
+	bucket string
+}
+
+// buildS3Config loads feature flags, decrypts credentials, and returns an S3 client + bucket name.
+func (s *FileService) buildS3Config(ctx context.Context) (*s3Config, error) {
+	flags, err := s.featureFlagRepo.GetFeatureFlags(ctx)
+	if err != nil {
+		return nil, err
+	}
+	if !flags.FileExplorerEnabled {
+		return nil, errors.New("file explorer is disabled")
+	}
+	if flags.S3Endpoint == "" || flags.S3Bucket == "" {
+		return nil, errors.New("S3 is not configured")
+	}
+
+	secretKey := ""
+	if flags.S3SecretKey != "" && s.encryptor != nil {
+		secretKey, err = s.encryptor.Decrypt(flags.S3SecretKey)
+		if err != nil {
+			return nil, errors.New("failed to decrypt S3 credentials")
+		}
+	}
+
+	region := flags.S3Region
+	if region == "" {
+		region = "us-east-1"
+	}
+
+	cfg := aws.Config{
+		Region:      region,
+		Credentials: credentials.NewStaticCredentialsProvider(flags.S3AccessKey, secretKey, ""),
+	}
+
+	client := s3.NewFromConfig(cfg, func(o *s3.Options) {
+		o.BaseEndpoint = aws.String(flags.S3Endpoint)
+		o.UsePathStyle = true
+	})
+
+	return &s3Config{client: client, bucket: flags.S3Bucket}, nil
+}
+
+// validateAccess ensures file explorer is enabled and the user is a member of the space.
+// Returns a ready S3 config on success.
+func (s *FileService) validateAccess(ctx context.Context, userIDHex, spaceIDHex string) (*s3Config, error) {
+	cfg, err := s.buildS3Config(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	userID, err := bson.ObjectIDFromHex(userIDHex)
+	if err != nil {
+		return nil, errors.New("access denied")
+	}
+	spaceID, err := bson.ObjectIDFromHex(spaceIDHex)
+	if err != nil {
+		return nil, errors.New("access denied")
+	}
+
+	if _, err := s.membershipRepo.GetUserMembership(ctx, userID, spaceID); err != nil {
+		return nil, errors.New("access denied")
+	}
+
+	return cfg, nil
+}
+
+// spaceBase returns the S3 key prefix for a space: "spaces/<spaceIDHex>/".
+func spaceBase(spaceIDHex string) string {
+	return "spaces/" + spaceIDHex + "/"
+}
+
+// resolveRelKey sanitises a relative key and returns the full S3 key,
+// rejecting anything that would escape the space prefix.
+func resolveRelKey(spaceIDHex, relKey string) (string, error) {
+	relKey = strings.TrimLeft(strings.TrimSpace(relKey), "/")
+	cleaned := path.Clean(relKey)
+	if cleaned == "." || cleaned == "" {
+		return "", errors.New("key is empty")
+	}
+	if strings.Contains(cleaned, "..") {
+		return "", errors.New("invalid key")
+	}
+	base := spaceBase(spaceIDHex)
+	full := base + cleaned
+	if !strings.HasPrefix(full, base) {
+		return "", errors.New("invalid key: outside space boundary")
+	}
+	return full, nil
+}
+
+// resolveRelPrefix sanitises a relative folder prefix and returns the full S3 prefix.
+// An empty relPrefix maps to the space root folder.
+func resolveRelPrefix(spaceIDHex, relPrefix string) (string, error) {
+	base := spaceBase(spaceIDHex)
+	relPrefix = strings.TrimLeft(strings.TrimSpace(relPrefix), "/")
+	if relPrefix == "" {
+		return base, nil
+	}
+	cleaned := path.Clean(relPrefix)
+	if cleaned == "." {
+		return base, nil
+	}
+	if strings.Contains(cleaned, "..") {
+		return "", errors.New("invalid prefix")
+	}
+	full := base + cleaned + "/"
+	if !strings.HasPrefix(full, base) {
+		return "", errors.New("invalid prefix: outside space boundary")
+	}
+	return full, nil
+}
+
+// ListObjects returns objects and virtual folders directly under relPrefix within the space.
+// Returned keys are relative to the space root (no "spaces/<spaceId>/" prefix).
+func (s *FileService) ListObjects(ctx context.Context, userIDHex, spaceIDHex, relPrefix string) ([]*S3Object, error) {
+	cfg, err := s.validateAccess(ctx, userIDHex, spaceIDHex)
+	if err != nil {
+		return nil, err
+	}
+
+	fullPrefix, err := resolveRelPrefix(spaceIDHex, relPrefix)
+	if err != nil {
+		return nil, err
+	}
+
+	base := spaceBase(spaceIDHex)
+	result, err := cfg.client.ListObjectsV2(ctx, &s3.ListObjectsV2Input{
+		Bucket:    aws.String(cfg.bucket),
+		Prefix:    aws.String(fullPrefix),
+		Delimiter: aws.String("/"),
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	var objects []*S3Object
+
+	for _, cp := range result.CommonPrefixes {
+		if cp.Prefix != nil {
+			objects = append(objects, &S3Object{
+				Key:      strings.TrimPrefix(*cp.Prefix, base),
+				IsFolder: true,
+			})
+		}
+	}
+
+	for _, obj := range result.Contents {
+		if obj.Key == nil || *obj.Key == fullPrefix {
+			continue
+		}
+		// Hide virtual .keep placeholder files used for folder creation
+		if path.Base(*obj.Key) == ".keep" {
+			continue
+		}
+		size := int64(0)
+		if obj.Size != nil {
+			size = *obj.Size
+		}
+		lastMod := ""
+		if obj.LastModified != nil {
+			lastMod = obj.LastModified.Format(time.RFC3339)
+		}
+		objects = append(objects, &S3Object{
+			Key:          strings.TrimPrefix(*obj.Key, base),
+			Size:         size,
+			LastModified: lastMod,
+		})
+	}
+
+	return objects, nil
+}
+
+// GetObjectContent streams an S3 object, enforcing space boundary.
+// relKey is relative to the space root.
+func (s *FileService) GetObjectContent(ctx context.Context, userIDHex, spaceIDHex, relKey string) (io.ReadCloser, string, error) {
+	cfg, err := s.validateAccess(ctx, userIDHex, spaceIDHex)
+	if err != nil {
+		return nil, "", err
+	}
+
+	fullKey, err := resolveRelKey(spaceIDHex, relKey)
+	if err != nil {
+		return nil, "", err
+	}
+
+	result, err := cfg.client.GetObject(ctx, &s3.GetObjectInput{
+		Bucket: aws.String(cfg.bucket),
+		Key:    aws.String(fullKey),
+	})
+	if err != nil {
+		return nil, "", err
+	}
+
+	contentType := "application/octet-stream"
+	if result.ContentType != nil {
+		contentType = *result.ContentType
+	}
+
+	return result.Body, contentType, nil
+}
+
+// UploadObject stores a file at relKey within the space.
+func (s *FileService) UploadObject(ctx context.Context, userIDHex, spaceIDHex, relKey, contentType string, body io.Reader, size int64) error {
+	cfg, err := s.validateAccess(ctx, userIDHex, spaceIDHex)
+	if err != nil {
+		return err
+	}
+
+	fullKey, err := resolveRelKey(spaceIDHex, relKey)
+	if err != nil {
+		return err
+	}
+
+	if contentType == "" {
+		contentType = "application/octet-stream"
+	}
+
+	input := &s3.PutObjectInput{
+		Bucket:      aws.String(cfg.bucket),
+		Key:         aws.String(fullKey),
+		Body:        body,
+		ContentType: aws.String(contentType),
+	}
+	if size > 0 {
+		input.ContentLength = aws.Int64(size)
+	}
+
+	_, err = cfg.client.PutObject(ctx, input)
+	return err
+}
+
+// CreateFolder creates a virtual folder by uploading a zero-byte .keep placeholder.
+func (s *FileService) CreateFolder(ctx context.Context, userIDHex, spaceIDHex, relPath string) error {
+	cfg, err := s.validateAccess(ctx, userIDHex, spaceIDHex)
+	if err != nil {
+		return err
+	}
+
+	base := spaceBase(spaceIDHex)
+	relPath = strings.Trim(relPath, "/")
+	cleaned := path.Clean(relPath)
+	if cleaned == "." || cleaned == "" || strings.Contains(cleaned, "..") {
+		return errors.New("invalid folder path")
+	}
+	fullKey := base + cleaned + "/.keep"
+	if !strings.HasPrefix(fullKey, base) {
+		return errors.New("invalid folder path: outside space boundary")
+	}
+
+	zero := int64(0)
+	_, err = cfg.client.PutObject(ctx, &s3.PutObjectInput{
+		Bucket:        aws.String(cfg.bucket),
+		Key:           aws.String(fullKey),
+		Body:          bytes.NewReader(nil),
+		ContentType:   aws.String("application/octet-stream"),
+		ContentLength: aws.Int64(zero),
+	})
+	return err
+}
+
+// DeleteObject removes a single object within the space.
+func (s *FileService) DeleteObject(ctx context.Context, userIDHex, spaceIDHex, relKey string) error {
+	cfg, err := s.validateAccess(ctx, userIDHex, spaceIDHex)
+	if err != nil {
+		return err
+	}
+
+	fullKey, err := resolveRelKey(spaceIDHex, relKey)
+	if err != nil {
+		return err
+	}
+
+	_, err = cfg.client.DeleteObject(ctx, &s3.DeleteObjectInput{
+		Bucket: aws.String(cfg.bucket),
+		Key:    aws.String(fullKey),
+	})
+	return err
+}
+
+// DeleteFolder recursively deletes all objects under relPrefix within the space.
+func (s *FileService) DeleteFolder(ctx context.Context, userIDHex, spaceIDHex, relPrefix string) error {
+	cfg, err := s.validateAccess(ctx, userIDHex, spaceIDHex)
+	if err != nil {
+		return err
+	}
+
+	fullPrefix, err := resolveRelPrefix(spaceIDHex, relPrefix)
+	if err != nil {
+		return err
+	}
+
+	// Safety net: refuse to delete the entire space root
+	if fullPrefix == spaceBase(spaceIDHex) {
+		return errors.New("cannot delete the space root folder")
+	}
+
+	paginator := s3.NewListObjectsV2Paginator(cfg.client, &s3.ListObjectsV2Input{
+		Bucket: aws.String(cfg.bucket),
+		Prefix: aws.String(fullPrefix),
+	})
+
+	var toDelete []types.ObjectIdentifier
+	for paginator.HasMorePages() {
+		page, err := paginator.NextPage(ctx)
+		if err != nil {
+			return err
+		}
+		for _, obj := range page.Contents {
+			if obj.Key != nil {
+				toDelete = append(toDelete, types.ObjectIdentifier{Key: obj.Key})
+			}
+		}
+	}
+
+	if len(toDelete) == 0 {
+		return nil
+	}
+
+	// Delete in batches of 1000 (S3 limit per DeleteObjects call)
+	for i := 0; i < len(toDelete); i += 1000 {
+		end := i + 1000
+		if end > len(toDelete) {
+			end = len(toDelete)
+		}
+		_, err := cfg.client.DeleteObjects(ctx, &s3.DeleteObjectsInput{
+			Bucket: aws.String(cfg.bucket),
+			Delete: &types.Delete{
+				Objects: toDelete[i:end],
+				Quiet:   aws.Bool(true),
+			},
+		})
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

backend/internal/domain/entities/auth.go

@@ -36,9 +36,15 @@ type LoginAttempt struct {
 
 // FeatureFlags controls app-wide behavior toggles.
 type FeatureFlags struct {
-	RegistrationEnabled  bool `bson:"registration_enabled"`
+	RegistrationEnabled  bool   `bson:"registration_enabled"`
-	ProviderLoginEnabled bool `bson:"provider_login_enabled"`
+	ProviderLoginEnabled bool   `bson:"provider_login_enabled"`
-	PublicSharingEnabled bool `bson:"public_sharing_enabled"`
+	PublicSharingEnabled bool   `bson:"public_sharing_enabled"`
+	FileExplorerEnabled  bool   `bson:"file_explorer_enabled"`
+	S3Endpoint           string `bson:"s3_endpoint,omitempty"`
+	S3Bucket             string `bson:"s3_bucket,omitempty"`
+	S3Region             string `bson:"s3_region,omitempty"`
+	S3AccessKey          string `bson:"s3_access_key,omitempty"`
+	S3SecretKey          string `bson:"s3_secret_key,omitempty"` // AES-256-GCM encrypted
 }
 
 // NewDefaultFeatureFlags returns safe defaults for a new deployment.
@@ -47,5 +53,6 @@ func NewDefaultFeatureFlags() *FeatureFlags {
 		RegistrationEnabled:  true,
 		ProviderLoginEnabled: true,
 		PublicSharingEnabled: true,
+		FileExplorerEnabled:  false,
 	}
 }

backend/internal/interfaces/handlers/file_handler.go

@@ -0,0 +1,273 @@
+package handlers
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"mime"
+	"net/http"
+	"path"
+	"strings"
+
+	"github.com/gorilla/mux"
+	"github.com/noteapp/backend/internal/application/services"
+	"github.com/noteapp/backend/internal/interfaces/middleware"
+)
+
+const maxUploadSize = 100 << 20 // 100 MB
+
+// FileHandler exposes S3 file explorer endpoints scoped to spaces.
+type FileHandler struct {
+	fileService *services.FileService
+}
+
+// NewFileHandler creates a new FileHandler.
+func NewFileHandler(fileService *services.FileService) *FileHandler {
+	return &FileHandler{fileService: fileService}
+}
+
+// extractContext extracts and validates spaceId (URL) and userId (JWT context).
+func (h *FileHandler) extractContext(r *http.Request) (spaceID, userID string, err error) {
+	spaceID = mux.Vars(r)["spaceId"]
+	if spaceID == "" {
+		return "", "", fmt.Errorf("missing spaceId")
+	}
+	userID, err = middleware.GetUserIDFromContext(r.Context())
+	return
+}
+
+// cleanKey sanitises a user-supplied relative key (strips leading slash, resolves .).
+func cleanKey(raw string) string {
+	k := strings.TrimLeft(strings.TrimSpace(raw), "/")
+	if c := path.Clean(k); c != "." {
+		return c
+	}
+	return ""
+}
+
+// cleanPrefix sanitises a user-supplied relative prefix.
+func cleanPrefix(raw string) string {
+	p := strings.TrimLeft(strings.TrimSpace(raw), "/")
+	if c := path.Clean(p); c != "." {
+		return c
+	}
+	return ""
+}
+
+// respondError maps service errors to appropriate HTTP status codes.
+func respondError(w http.ResponseWriter, err error) {
+	msg := err.Error()
+	switch {
+	case strings.Contains(msg, "access denied"), strings.Contains(msg, "disabled"):
+		http.Error(w, msg, http.StatusForbidden)
+	default:
+		http.Error(w, msg, http.StatusBadRequest)
+	}
+}
+
+// ListFiles handles GET /api/v1/spaces/{spaceId}/files/list?prefix=
+func (h *FileHandler) ListFiles(w http.ResponseWriter, r *http.Request) {
+	spaceID, userID, err := h.extractContext(r)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	relPrefix := cleanPrefix(r.URL.Query().Get("prefix"))
+	objects, err := h.fileService.ListObjects(r.Context(), userID, spaceID, relPrefix)
+	if err != nil {
+		respondError(w, err)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(map[string]interface{}{
+		"objects": objects,
+		"prefix":  relPrefix,
+	})
+}
+
+// GetFile handles GET /api/v1/spaces/{spaceId}/files/object?key=
+// Also accepts ?token= as a fallback auth mechanism so markdown images render in-browser.
+func (h *FileHandler) GetFile(w http.ResponseWriter, r *http.Request) {
+	spaceID, userID, err := h.extractContext(r)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	relKey := cleanKey(r.URL.Query().Get("key"))
+	if relKey == "" {
+		http.Error(w, "key is required", http.StatusBadRequest)
+		return
+	}
+
+	body, contentType, err := h.fileService.GetObjectContent(r.Context(), userID, spaceID, relKey)
+	if err != nil {
+		if strings.Contains(err.Error(), "access denied") {
+			http.Error(w, "access denied", http.StatusForbidden)
+			return
+		}
+		http.Error(w, "file not found", http.StatusNotFound)
+		return
+	}
+	defer body.Close()
+
+	w.Header().Set("Content-Type", contentType)
+	w.Header().Set("Cache-Control", "private, max-age=3600")
+	io.Copy(w, body) //nolint:errcheck
+}
+
+// UploadFile handles POST /api/v1/spaces/{spaceId}/files/upload (multipart/form-data)
+// Form fields:
+//   - path: optional relative folder within the space (e.g. "docs/2024")
+//   - files: one or more file uploads
+func (h *FileHandler) UploadFile(w http.ResponseWriter, r *http.Request) {
+	spaceID, userID, err := h.extractContext(r)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	if err := r.ParseMultipartForm(maxUploadSize); err != nil {
+		http.Error(w, "request too large", http.StatusRequestEntityTooLarge)
+		return
+	}
+
+	relFolder := cleanPrefix(r.FormValue("path"))
+	fileHeaders := r.MultipartForm.File["files"]
+	if len(fileHeaders) == 0 {
+		http.Error(w, "no files provided", http.StatusBadRequest)
+		return
+	}
+
+	var uploaded []string
+	for _, fh := range fileHeaders {
+		filename := path.Base(fh.Filename)
+		if filename == "." || filename == "" {
+			continue
+		}
+
+		var relKey string
+		if relFolder != "" {
+			relKey = relFolder + "/" + filename
+		} else {
+			relKey = filename
+		}
+
+		// Detect content-type from header then extension
+		ct := fh.Header.Get("Content-Type")
+		if ct == "" || ct == "application/octet-stream" {
+			if ext := path.Ext(filename); ext != "" {
+				if t := mime.TypeByExtension(ext); t != "" {
+					ct = t
+				}
+			}
+		}
+		if ct == "" {
+			ct = "application/octet-stream"
+		}
+
+		f, err := fh.Open()
+		if err != nil {
+			http.Error(w, "failed to read uploaded file", http.StatusInternalServerError)
+			return
+		}
+		uploadErr := h.fileService.UploadObject(r.Context(), userID, spaceID, relKey, ct, f, fh.Size)
+		f.Close()
+		if uploadErr != nil {
+			respondError(w, uploadErr)
+			return
+		}
+		uploaded = append(uploaded, relKey)
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusCreated)
+	json.NewEncoder(w).Encode(map[string]interface{}{"uploaded": uploaded})
+}
+
+// CreateFolder handles POST /api/v1/spaces/{spaceId}/files/folder
+// JSON body: {"path": "new-folder-name"}
+func (h *FileHandler) CreateFolder(w http.ResponseWriter, r *http.Request) {
+	spaceID, userID, err := h.extractContext(r)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	var body struct {
+		Path string `json:"path"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		http.Error(w, "invalid request body", http.StatusBadRequest)
+		return
+	}
+
+	relPath := cleanPrefix(body.Path)
+	if relPath == "" {
+		http.Error(w, "path is required", http.StatusBadRequest)
+		return
+	}
+
+	if err := h.fileService.CreateFolder(r.Context(), userID, spaceID, relPath); err != nil {
+		respondError(w, err)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusCreated)
+	json.NewEncoder(w).Encode(map[string]string{"path": relPath})
+}
+
+// DeleteFile handles DELETE /api/v1/spaces/{spaceId}/files/object?key=
+func (h *FileHandler) DeleteFile(w http.ResponseWriter, r *http.Request) {
+	spaceID, userID, err := h.extractContext(r)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	relKey := cleanKey(r.URL.Query().Get("key"))
+	if relKey == "" {
+		http.Error(w, "key is required", http.StatusBadRequest)
+		return
+	}
+
+	if err := h.fileService.DeleteObject(r.Context(), userID, spaceID, relKey); err != nil {
+		if strings.Contains(err.Error(), "access denied") {
+			http.Error(w, "access denied", http.StatusForbidden)
+			return
+		}
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// DeleteFolder handles DELETE /api/v1/spaces/{spaceId}/files/folder?prefix=
+func (h *FileHandler) DeleteFolder(w http.ResponseWriter, r *http.Request) {
+	spaceID, userID, err := h.extractContext(r)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	relPrefix := cleanPrefix(r.URL.Query().Get("prefix"))
+	if relPrefix == "" {
+		http.Error(w, "prefix is required", http.StatusBadRequest)
+		return
+	}
+
+	if err := h.fileService.DeleteFolder(r.Context(), userID, spaceID, relPrefix); err != nil {
+		if strings.Contains(err.Error(), "access denied") {
+			http.Error(w, "access denied", http.StatusForbidden)
+			return
+		}
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	w.WriteHeader(http.StatusNoContent)
+}

backend/internal/interfaces/middleware/auth.go

@@ -41,8 +41,14 @@ func (m *AuthMiddleware) Middleware(next http.Handler) http.Handler {
 			return
 		}
 
-		// Extract token from Authorization header
+		// Extract token from Authorization header.
+		// For GET /files/object, also accept ?token= so markdown images render in-browser.
 		authHeader := r.Header.Get("Authorization")
+		if authHeader == "" && r.Method == http.MethodGet && strings.HasSuffix(r.URL.Path, "/files/object") {
+			if tok := r.URL.Query().Get("token"); tok != "" {
+				authHeader = "Bearer " + tok
+			}
+		}
 		if authHeader == "" {
 			http.Error(w, "Missing authorization header", http.StatusUnauthorized)
 			return

frontend/src/App.vue

@@ -174,11 +174,12 @@
                         :note="selectedNote"
                         :category-options="categoryOptions"
                         :can-delete="canDeleteNotes"
+                        :space-id="currentSpace?.id"
                         @save="updateNote"
                         @delete="deleteNote"
                         @cancel="cancelEditingNote"
                     />
-                    <NoteViewer v-else-if="selectedNote" :note="selectedNote" :category-options="categoryOptions" />
+                    <NoteViewer v-else-if="selectedNote" :note="selectedNote" :category-options="categoryOptions" :space-id="currentSpace?.id" />
                     <NoteList
                         v-else
                         :notes="displayedNotes"

frontend/src/components/FileExplorer.vue

@@ -0,0 +1,331 @@
+<template>
+    <div
+        class="file-explorer d-flex flex-column border rounded"
+        style="min-height: 300px"
+        @dragover.prevent="dragOver = true"
+        @dragleave="dragOver = false"
+        @drop.prevent="handleDrop"
+        :class="{ 'drag-active': dragOver }"
+    >
+        <!-- Breadcrumb toolbar -->
+        <div class="file-explorer-header px-2 py-1 border-bottom bg-light d-flex align-items-center gap-1 flex-wrap">
+            <i class="mdi mdi-folder-network-outline text-muted me-1" aria-hidden="true"></i>
+            <button class="btn btn-link btn-sm p-0 text-decoration-none text-dark" @click="navigateTo('')">Space Files</button>
+            <template v-for="(seg, idx) in breadcrumbs" :key="idx">
+                <span class="text-muted">/</span>
+                <button class="btn btn-link btn-sm p-0 text-decoration-none text-dark" @click="navigateTo(seg.prefix)">{{ seg.name }}</button>
+            </template>
+            <div class="ms-auto d-flex gap-1">
+                <button class="btn btn-sm btn-outline-secondary py-0 px-1" title="Upload files" @click="fileInputRef.click()">
+                    <i class="mdi mdi-upload" aria-hidden="true"></i>
+                </button>
+                <button class="btn btn-sm btn-outline-secondary py-0 px-1" title="New folder" @click="showNewFolderInput = !showNewFolderInput">
+                    <i class="mdi mdi-folder-plus-outline" aria-hidden="true"></i>
+                </button>
+                <button class="btn btn-sm btn-link p-0 text-muted" title="Refresh" @click="loadFiles">
+                    <i class="mdi mdi-refresh" aria-hidden="true"></i>
+                </button>
+            </div>
+        </div>
+
+        <!-- New folder input -->
+        <div v-if="showNewFolderInput" class="px-2 py-1 border-bottom bg-white d-flex gap-1">
+            <input
+                ref="newFolderInputRef"
+                v-model="newFolderName"
+                type="text"
+                class="form-control form-control-sm"
+                placeholder="Folder name"
+                @keyup.enter="createFolder"
+                @keyup.esc="showNewFolderInput = false"
+            />
+            <button class="btn btn-sm btn-primary" @click="createFolder">Create</button>
+            <button class="btn btn-sm btn-secondary" @click="showNewFolderInput = false">Cancel</button>
+        </div>
+
+        <!-- Upload progress -->
+        <div v-if="uploading" class="px-2 py-1 bg-light border-bottom">
+            <div class="d-flex align-items-center gap-2">
+                <div class="progress flex-grow-1" style="height: 6px">
+                    <div class="progress-bar progress-bar-striped progress-bar-animated" :style="{ width: uploadProgress + '%' }"></div>
+                </div>
+                <span class="text-muted" style="font-size: 0.7rem">{{ uploadProgress }}%</span>
+            </div>
+        </div>
+
+        <!-- Error message -->
+        <div v-if="error" class="alert alert-danger alert-sm m-1 p-1 small mb-0" role="alert">
+            <i class="mdi mdi-alert-circle-outline me-1" aria-hidden="true"></i>{{ error }}
+            <button type="button" class="btn-close float-end" style="font-size: 0.6rem" @click="error = ''"></button>
+        </div>
+
+        <!-- Loading / empty -->
+        <div v-if="loading" class="p-3 text-muted text-center small flex-grow-1"><i class="mdi mdi-loading mdi-spin me-1" aria-hidden="true"></i> Loading...</div>
+        <div v-else-if="!error && objects.length === 0" class="p-3 text-muted text-center small flex-grow-1">
+            <i class="mdi mdi-cloud-upload-outline d-block mb-1" style="font-size: 1.5rem" aria-hidden="true"></i>
+            Drop files here or click Upload
+        </div>
+
+        <!-- File list -->
+        <div v-else class="file-list flex-grow-1 overflow-auto">
+            <div
+                v-for="obj in objects"
+                :key="obj.key"
+                class="file-item d-flex align-items-center gap-1 px-2 py-1"
+                :title="obj.is_folder ? 'Open folder' : 'Insert into note'"
+                @click="handleClick(obj)"
+            >
+                <i :class="fileIcon(obj)" style="font-size: 1rem; width: 1.1rem; flex-shrink: 0" aria-hidden="true"></i>
+                <span class="flex-grow-1 text-truncate" style="font-size: 0.82rem">{{ displayName(obj) }}</span>
+                <span v-if="!obj.is_folder && obj.size > 0" class="text-muted flex-shrink-0" style="font-size: 0.68rem">{{ formatSize(obj.size) }}</span>
+                <button class="btn-delete btn btn-sm btn-link p-0 text-danger ms-1" :title="obj.is_folder ? 'Delete folder' : 'Delete file'" @click.stop="deleteItem(obj)">
+                    <i class="mdi mdi-trash-can-outline" style="font-size: 0.85rem" aria-hidden="true"></i>
+                </button>
+            </div>
+        </div>
+
+        <!-- Hidden file input -->
+        <input ref="fileInputRef" type="file" multiple class="d-none" @change="handleFilePick" />
+    </div>
+</template>
+
+<script setup>
+import { ref, computed, watch, nextTick } from "vue";
+import apiClient from "../services/apiClient";
+
+const props = defineProps({
+    spaceId: {
+        type: String,
+        required: true,
+    },
+    modelValue: {
+        type: String,
+        default: "",
+    },
+});
+
+const emit = defineEmits(["insert", "update:modelValue"]);
+
+const objects = ref([]);
+const loading = ref(false);
+const error = ref("");
+const currentPrefix = ref(props.modelValue || "");
+const dragOver = ref(false);
+const uploading = ref(false);
+const uploadProgress = ref(0);
+const showNewFolderInput = ref(false);
+const newFolderName = ref("");
+const fileInputRef = ref(null);
+const newFolderInputRef = ref(null);
+
+const breadcrumbs = computed(() => {
+    if (!currentPrefix.value) return [];
+    const parts = currentPrefix.value.replace(/\/$/, "").split("/").filter(Boolean);
+    return parts.map((name, i) => ({
+        name,
+        prefix: parts.slice(0, i + 1).join("/"),
+    }));
+});
+
+const loadFiles = async () => {
+    if (!props.spaceId) return;
+    loading.value = true;
+    error.value = "";
+    try {
+        const res = await apiClient.get(`/api/v1/spaces/${props.spaceId}/files/list`, {
+            params: { prefix: currentPrefix.value },
+        });
+        objects.value = res.data.objects || [];
+    } catch (e) {
+        error.value = e.response?.data || "Failed to load files";
+    } finally {
+        loading.value = false;
+    }
+};
+
+const navigateTo = (prefix) => {
+    currentPrefix.value = prefix;
+    emit("update:modelValue", prefix);
+    loadFiles();
+};
+
+const handleClick = (obj) => {
+    if (obj.is_folder) {
+        navigateTo(obj.key.replace(/\/$/, ""));
+        return;
+    }
+    const url = `/api/v1/spaces/${props.spaceId}/files/object?key=${encodeURIComponent(obj.key)}`;
+    const name = displayName(obj);
+    const ext = name.split(".").pop().toLowerCase();
+    const imageExts = ["jpg", "jpeg", "png", "gif", "webp", "svg", "bmp", "avif"];
+    const snippet = imageExts.includes(ext) ? `![${name}](${url})` : `[${name}](${url})`;
+    emit("insert", snippet);
+};
+
+const handleFilePick = (e) => {
+    const files = Array.from(e.target.files || []);
+    if (files.length > 0) uploadFiles(files);
+    e.target.value = "";
+};
+
+const handleDrop = (e) => {
+    dragOver.value = false;
+    const files = Array.from(e.dataTransfer?.files || []);
+    if (files.length > 0) uploadFiles(files);
+};
+
+const uploadFiles = async (files) => {
+    if (!props.spaceId || files.length === 0) return;
+    uploading.value = true;
+    uploadProgress.value = 0;
+    error.value = "";
+
+    const form = new FormData();
+    form.append("path", currentPrefix.value);
+    for (const f of files) form.append("files", f);
+
+    try {
+        await apiClient.post(`/api/v1/spaces/${props.spaceId}/files/upload`, form, {
+            headers: { "Content-Type": "multipart/form-data" },
+            onUploadProgress: (e) => {
+                uploadProgress.value = e.total ? Math.round((e.loaded * 100) / e.total) : 50;
+            },
+        });
+        await loadFiles();
+    } catch (e) {
+        error.value = e.response?.data || "Upload failed";
+    } finally {
+        uploading.value = false;
+        uploadProgress.value = 0;
+    }
+};
+
+const createFolder = async () => {
+    const name = newFolderName.value.trim();
+    if (!name || !props.spaceId) return;
+    const path = currentPrefix.value ? `${currentPrefix.value}/${name}` : name;
+    error.value = "";
+    try {
+        await apiClient.post(`/api/v1/spaces/${props.spaceId}/files/folder`, { path });
+        newFolderName.value = "";
+        showNewFolderInput.value = false;
+        await loadFiles();
+    } catch (e) {
+        error.value = e.response?.data || "Failed to create folder";
+    }
+};
+
+const deleteItem = async (obj) => {
+    const label = displayName(obj);
+    if (!confirm(`Delete "${label}"?${obj.is_folder ? "\n\nThis will delete all files inside the folder." : ""}`)) return;
+    error.value = "";
+    try {
+        if (obj.is_folder) {
+            const prefix = obj.key.replace(/\/$/, "");
+            await apiClient.delete(`/api/v1/spaces/${props.spaceId}/files/folder`, { params: { prefix } });
+        } else {
+            await apiClient.delete(`/api/v1/spaces/${props.spaceId}/files/object`, { params: { key: obj.key } });
+        }
+        await loadFiles();
+    } catch (e) {
+        error.value = e.response?.data || "Delete failed";
+    }
+};
+
+const displayName = (obj) => {
+    const key = obj.is_folder ? obj.key.replace(/\/$/, "") : obj.key;
+    return key.split("/").pop() || key;
+};
+
+const fileIcon = (obj) => {
+    if (obj.is_folder) return "mdi mdi-folder text-warning";
+    const ext = displayName(obj).split(".").pop().toLowerCase();
+    if (["jpg", "jpeg", "png", "gif", "webp", "svg", "bmp", "avif"].includes(ext)) return "mdi mdi-file-image text-info";
+    if (["pdf"].includes(ext)) return "mdi mdi-file-pdf-box text-danger";
+    if (["doc", "docx", "odt"].includes(ext)) return "mdi mdi-file-word text-primary";
+    if (["xls", "xlsx", "ods"].includes(ext)) return "mdi mdi-file-excel text-success";
+    if (["zip", "tar", "gz", "rar", "7z"].includes(ext)) return "mdi mdi-folder-zip text-secondary";
+    if (["mp4", "mov", "avi", "mkv", "webm"].includes(ext)) return "mdi mdi-file-video";
+    if (["mp3", "wav", "ogg", "flac"].includes(ext)) return "mdi mdi-file-music";
+    if (["js", "ts", "py", "go", "java", "c", "cpp", "rs", "html", "css", "json", "yaml", "yml", "sh"].includes(ext)) return "mdi mdi-file-code text-success";
+    return "mdi mdi-file-outline text-muted";
+};
+
+const formatSize = (bytes) => {
+    if (bytes < 1024) return `${bytes} B`;
+    if (bytes < 1048576) return `${(bytes / 1024).toFixed(1)} KB`;
+    return `${(bytes / 1048576).toFixed(1)} MB`;
+};
+
+// Load on mount and when spaceId or prefix changes from parent
+watch(
+    () => props.spaceId,
+    (v) => {
+        if (v) loadFiles();
+    },
+    { immediate: true },
+);
+
+watch(
+    () => props.modelValue,
+    (val) => {
+        if (val !== currentPrefix.value) {
+            currentPrefix.value = val || "";
+            loadFiles();
+        }
+    },
+);
+
+watch(showNewFolderInput, async (v) => {
+    if (v) {
+        await nextTick();
+        newFolderInputRef.value?.focus();
+    }
+});
+</script>
+
+<style scoped>
+.file-explorer {
+    background: #fff;
+    overflow: hidden;
+}
+
+.file-explorer-header {
+    font-size: 0.8rem;
+    min-height: 36px;
+}
+
+.file-list {
+    max-height: 480px;
+}
+
+.file-item {
+    border-bottom: 1px solid #f0f0f0;
+    cursor: pointer;
+    transition: background 0.1s;
+    color: #333;
+    line-height: 1.3;
+}
+
+.file-item:last-child {
+    border-bottom: none;
+}
+
+.file-item:hover {
+    background-color: #f0f4ff;
+}
+
+.drag-active {
+    outline: 2px dashed #0d6efd;
+    outline-offset: -2px;
+}
+
+.btn-delete {
+    opacity: 0;
+    transition: opacity 0.1s;
+}
+
+.file-item:hover .btn-delete {
+    opacity: 1;
+}
+</style>

frontend/src/components/NoteEditor.vue

@@ -4,6 +4,16 @@
             <button class="btn btn-sm btn-primary" @click="saveNote">Save</button>
             <button v-if="canDelete" class="btn btn-sm btn-danger ms-2" @click="confirmDelete">Delete</button>
             <button class="btn btn-sm btn-outline-secondary ms-2" @click="emit('cancel')">Cancel</button>
+            <button
+                v-if="fileExplorerEnabled"
+                class="btn btn-sm ms-2"
+                :class="showFileExplorer ? 'btn-secondary' : 'btn-outline-secondary'"
+                :title="showFileExplorer ? 'Hide file explorer' : 'Browse & insert files'"
+                @click="showFileExplorer = !showFileExplorer"
+            >
+                <i class="mdi mdi-folder-open-outline me-1" aria-hidden="true"></i>
+                Files
+            </button>
             <span class="save-status ms-auto" :class="saveState">{{ saveStatusLabel }}</span>
         </div>
 
@@ -16,15 +26,19 @@
             </div>
 
             <div class="row">
-                <div class="col-12 col-md-6">
+                <div :class="showFileExplorer ? 'col-12 col-md-5' : 'col-12 col-md-6'">
-                    <textarea v-model="editingNote.content" class="form-control editor-textarea" placeholder="Write your note in markdown..." @input="autoSave"></textarea>
+                    <textarea ref="contentTextareaRef" v-model="editingNote.content" class="form-control editor-textarea" placeholder="Write your note in markdown..." @input="autoSave"></textarea>
                 </div>
 
-                <div class="col-12 col-md-6 mt-3 mt-md-0">
+                <div :class="showFileExplorer ? 'col-12 col-md-4 mt-3 mt-md-0' : 'col-12 col-md-6 mt-3 mt-md-0'">
                     <div class="preview-pane border rounded p-3">
                         <div v-html="renderedMarkdown"></div>
                     </div>
                 </div>
+
+                <div v-if="showFileExplorer" class="col-12 col-md-3 mt-3 mt-md-0">
+                    <FileExplorer v-model="fileExplorerPrefix" :space-id="spaceId" @insert="insertAtCursor" />
+                </div>
             </div>
 
             <div class="mt-3">
@@ -73,10 +87,13 @@
 </template>
 
 <script setup>
-import { ref, computed, watch, onBeforeUnmount, onMounted } from "vue";
+import { ref, computed, watch, onBeforeUnmount, onMounted, nextTick } from "vue";
 import { marked } from "marked";
 import DOMPurify from "dompurify";
 import { useSettingsStore } from "../stores/settingsStore";
+import { useAuthStore } from "../stores/authStore";
+import { preprocessMarkdown } from "../utils/markdown.js";
+import FileExplorer from "./FileExplorer.vue";
 
 const props = defineProps({
     note: {
@@ -91,13 +108,22 @@ const props = defineProps({
         type: Boolean,
         default: true,
     },
+    spaceId: {
+        type: String,
+        default: "",
+    },
 });
 
 const emit = defineEmits(["save", "delete", "cancel"]);
 const settingsStore = useSettingsStore();
+const authStore = useAuthStore();
 const publicSharingEnabled = ref(true);
+const fileExplorerEnabled = computed(() => settingsStore.fileExplorerEnabled);
 
 const editingNote = ref({ ...props.note });
+const contentTextareaRef = ref(null);
+const showFileExplorer = ref(false);
+const fileExplorerPrefix = ref("");
 const tagsInput = ref(props.note.tags?.join(", ") || "");
 const passwordAction = ref("keep");
 const notePassword = ref("");
@@ -106,8 +132,18 @@ const saveState = ref("saved");
 const saveStateTimeout = ref(null);
 
 const renderedMarkdown = computed(() => {
-    const html = marked.parse(editingNote.value.content || "");
+    const html = marked.parse(preprocessMarkdown(editingNote.value.content || ""));
-    return DOMPurify.sanitize(html);
+    let clean = DOMPurify.sanitize(html);
+    // Inject access token into space file API URLs so images render without a separate JS fetch
+    const token = authStore.accessToken;
+    if (token && props.spaceId) {
+        clean = clean.replace(/((?:src|href)=["'])([^"']*\/api\/v1\/spaces\/[^"']*\/files\/object[^"']*)(["'])/g, (_, attr, url, quote) => {
+            if (url.includes("token=")) return attr + url + quote;
+            const sep = url.includes("?") ? "&" : "?";
+            return `${attr}${url}${sep}token=${encodeURIComponent(token)}${quote}`;
+        });
+    }
+    return clean;
 });
 
 const saveStatusLabel = computed(() => {
@@ -197,6 +233,27 @@ const confirmDelete = () => {
     }
 };
 
+/** Insert markdown snippet at the textarea cursor position. */
+const insertAtCursor = (snippet) => {
+    const textarea = contentTextareaRef.value;
+    if (!textarea) {
+        editingNote.value.content = (editingNote.value.content || "") + snippet;
+        autoSave();
+        return;
+    }
+    const start = textarea.selectionStart ?? editingNote.value.content?.length ?? 0;
+    const end = textarea.selectionEnd ?? start;
+    const before = (editingNote.value.content || "").substring(0, start);
+    const after = (editingNote.value.content || "").substring(end);
+    editingNote.value.content = before + snippet + after;
+    autoSave();
+    nextTick(() => {
+        const newPos = start + snippet.length;
+        textarea.setSelectionRange(newPos, newPos);
+        textarea.focus();
+    });
+};
+
 onBeforeUnmount(() => {
     clearTimeout(saveTimeout.value);
     clearTimeout(saveStateTimeout.value);

frontend/src/components/NoteViewer.vue

@@ -32,6 +32,8 @@
 import { computed } from "vue";
 import { marked } from "marked";
 import DOMPurify from "dompurify";
+import { useAuthStore } from "../stores/authStore";
+import { preprocessMarkdown } from "../utils/markdown.js";
 
 const props = defineProps({
     note: {
@@ -42,11 +44,26 @@ const props = defineProps({
         type: Array,
         default: () => [],
     },
+    spaceId: {
+        type: String,
+        default: "",
+    },
 });
 
+const authStore = useAuthStore();
+
 const renderedMarkdown = computed(() => {
-    const html = marked.parse(props.note.content || "");
+    const html = marked.parse(preprocessMarkdown(props.note.content || ""));
-    return DOMPurify.sanitize(html);
+    let clean = DOMPurify.sanitize(html);
+    const token = authStore.accessToken;
+    if (token && props.spaceId) {
+        clean = clean.replace(/((?:src|href)=["'])([^"']*\/api\/v1\/spaces\/[^"']*\/files\/object[^"']*)(["'])/g, (_, attr, url, quote) => {
+            if (url.includes("token=")) return attr + url + quote;
+            const sep = url.includes("?") ? "&" : "?";
+            return `${attr}${url}${sep}token=${encodeURIComponent(token)}${quote}`;
+        });
+    }
+    return clean;
 });
 
 const categoryLabel = computed(() => {

frontend/src/pages/Admin.vue

@@ -254,6 +254,49 @@
                         </div>
                     </div>
 
+                    <div class="feature-flag-item border rounded p-3">
+                        <div class="d-flex justify-content-between align-items-center mb-0" :class="{ 'mb-3': featureFlagsForm.file_explorer_enabled }">
+                            <div>
+                                <div class="fw-semibold">Enable File Explorer</div>
+                                <div class="small text-muted">Allow users to browse and insert files from an S3 bucket directly into notes.</div>
+                            </div>
+                            <div class="form-check form-switch m-0">
+                                <input id="flag-file-explorer" v-model="featureFlagsForm.file_explorer_enabled" class="form-check-input" type="checkbox" />
+                            </div>
+                        </div>
+                        <div v-if="featureFlagsForm.file_explorer_enabled" class="row g-2 mt-1">
+                            <div class="col-md-6">
+                                <label class="form-label small mb-1">S3 Endpoint URL</label>
+                                <input v-model="featureFlagsForm.s3_endpoint" type="url" class="form-control form-control-sm" placeholder="https://s3.amazonaws.com or custom endpoint" />
+                            </div>
+                            <div class="col-md-6">
+                                <label class="form-label small mb-1">Bucket Name</label>
+                                <input v-model="featureFlagsForm.s3_bucket" type="text" class="form-control form-control-sm" placeholder="my-bucket" />
+                            </div>
+                            <div class="col-md-4">
+                                <label class="form-label small mb-1">Region</label>
+                                <input v-model="featureFlagsForm.s3_region" type="text" class="form-control form-control-sm" placeholder="us-east-1" />
+                            </div>
+                            <div class="col-md-4">
+                                <label class="form-label small mb-1">Access Key</label>
+                                <input v-model="featureFlagsForm.s3_access_key" type="text" class="form-control form-control-sm" autocomplete="off" />
+                            </div>
+                            <div class="col-md-4">
+                                <label class="form-label small mb-1">Secret Key</label>
+                                <input
+                                    v-model="featureFlagsForm.s3_secret_key"
+                                    type="password"
+                                    class="form-control form-control-sm"
+                                    :placeholder="featureFlagsForm.s3_secret_key_set ? 'Leave blank to keep current secret' : 'Enter secret key'"
+                                    autocomplete="new-password"
+                                />
+                                <div v-if="featureFlagsForm.s3_secret_key_set && !featureFlagsForm.s3_secret_key" class="small text-success mt-1">
+                                    <i class="mdi mdi-check-circle-outline" aria-hidden="true"></i> Secret key is set
+                                </div>
+                            </div>
+                        </div>
+                    </div>
+
                     <div class="d-flex justify-content-end">
                         <button class="btn btn-primary" :disabled="savingFeatureFlags" @click="saveFeatureFlags">
                             {{ savingFeatureFlags ? "Saving..." : "Save Feature Flags" }}
@@ -364,6 +407,13 @@ const featureFlagsForm = ref({
     registration_enabled: true,
     provider_login_enabled: true,
     public_sharing_enabled: true,
+    file_explorer_enabled: false,
+    s3_endpoint: "",
+    s3_bucket: "",
+    s3_region: "",
+    s3_access_key: "",
+    s3_secret_key: "",
+    s3_secret_key_set: false,
 });
 
 const clearMessages = () => {
@@ -584,6 +634,13 @@ const loadFeatureFlags = async () => {
             registration_enabled: !!res.data.registration_enabled,
             provider_login_enabled: !!res.data.provider_login_enabled,
             public_sharing_enabled: !!res.data.public_sharing_enabled,
+            file_explorer_enabled: !!res.data.file_explorer_enabled,
+            s3_endpoint: res.data.s3_endpoint || "",
+            s3_bucket: res.data.s3_bucket || "",
+            s3_region: res.data.s3_region || "",
+            s3_access_key: res.data.s3_access_key || "",
+            s3_secret_key: "", // never pre-fill the secret
+            s3_secret_key_set: !!res.data.s3_secret_key_set,
         };
     } catch (e) {
         error.value = e.response?.data || "Failed to load feature flags.";
@@ -596,11 +653,28 @@ const saveFeatureFlags = async () => {
     savingFeatureFlags.value = true;
     clearMessages();
     try {
-        const res = await apiClient.put("/api/v1/admin/feature-flags", featureFlagsForm.value);
+        const res = await apiClient.put("/api/v1/admin/feature-flags", {
+            registration_enabled: featureFlagsForm.value.registration_enabled,
+            provider_login_enabled: featureFlagsForm.value.provider_login_enabled,
+            public_sharing_enabled: featureFlagsForm.value.public_sharing_enabled,
+            file_explorer_enabled: featureFlagsForm.value.file_explorer_enabled,
+            s3_endpoint: featureFlagsForm.value.s3_endpoint,
+            s3_bucket: featureFlagsForm.value.s3_bucket,
+            s3_region: featureFlagsForm.value.s3_region,
+            s3_access_key: featureFlagsForm.value.s3_access_key,
+            s3_secret_key: featureFlagsForm.value.s3_secret_key, // blank = keep existing
+        });
         featureFlagsForm.value = {
             registration_enabled: !!res.data.registration_enabled,
             provider_login_enabled: !!res.data.provider_login_enabled,
             public_sharing_enabled: !!res.data.public_sharing_enabled,
+            file_explorer_enabled: !!res.data.file_explorer_enabled,
+            s3_endpoint: res.data.s3_endpoint || "",
+            s3_bucket: res.data.s3_bucket || "",
+            s3_region: res.data.s3_region || "",
+            s3_access_key: res.data.s3_access_key || "",
+            s3_secret_key: "",
+            s3_secret_key_set: !!res.data.s3_secret_key_set,
         };
         successMessage.value = "Feature flags updated.";
     } catch (e) {

frontend/src/stores/settingsStore.js

@@ -6,6 +6,7 @@ const DEFAULT_FLAGS = {
     registration_enabled: true,
     provider_login_enabled: true,
     public_sharing_enabled: true,
+    file_explorer_enabled: false,
 };
 
 export const useSettingsStore = defineStore("settings", () => {
@@ -15,6 +16,7 @@ export const useSettingsStore = defineStore("settings", () => {
     const registrationEnabled = computed(() => !!featureFlags.value.registration_enabled);
     const providerLoginEnabled = computed(() => !!featureFlags.value.provider_login_enabled);
     const publicSharingEnabled = computed(() => !!featureFlags.value.public_sharing_enabled);
+    const fileExplorerEnabled = computed(() => !!featureFlags.value.file_explorer_enabled);
 
     const loadFeatureFlags = async (force = false) => {
         if (flagsLoaded.value && !force) {
@@ -42,6 +44,7 @@ export const useSettingsStore = defineStore("settings", () => {
         registrationEnabled,
         providerLoginEnabled,
         publicSharingEnabled,
+        fileExplorerEnabled,
         loadFeatureFlags,
     };
 });

frontend/src/utils/markdown.js

@@ -0,0 +1,29 @@
+/**
+ * Preprocesses markdown content to support extended image size syntax:
+ *
+ *   ![alt](url =WIDTHxHEIGHT)
+ *   ![alt](url "title" =WIDTHxHEIGHT)
+ *
+ * WIDTH and HEIGHT are pixel values or percentages (e.g. 50%).
+ * Either can be omitted:
+ *   =200x   → width 200 only
+ *   =x150   → height 150 only
+ *
+ * The syntax is transformed into a plain <img> tag before passing to marked
+ * because CommonMark terminates the link destination at whitespace, making it
+ * impossible for marked to see the size spec otherwise.
+ */
+export function preprocessMarkdown(content) {
+    if (!content) return content;
+    return content.replace(
+        /!\[([^\]]*)\]\(([^\s)"]+)(?:\s+"([^"]*)")?\s+=(\d*%?)[xX](\d*%?)\)/gi,
+        (_, alt, url, title, w, h) => {
+            const safeAlt = alt.replace(/"/g, "&quot;");
+            let attrs = `src="${url}" alt="${safeAlt}"`;
+            if (title) attrs += ` title="${title.replace(/"/g, "&quot;")}"`;
+            if (w) attrs += ` width="${w}"`;
+            if (h) attrs += ` height="${h}"`;
+            return `<img ${attrs}>`;
+        },
+    );
+}