Migrate save sync to use server-side negotiate API

.env-dev

@@ -12,3 +12,7 @@ ENVIRONMENT=DEV
 
 CFW=
 BASE_PATH=
+
+DEVICE_IP_ADDRESS=
+PRIVATE_KEY_PATH=
+SSH_PASSWORD=

app/transitions.go

@@ -283,6 +283,7 @@ func transitionSaveSync(ctx *transitionContext, result any) (router.Screen, any)
 		Items:           conflicts,
 		AllItems:        r.Items,
 		ConflictIndices: r.ConflictIndices,
+		SessionID:       r.SessionID,
 	}
 }
 
@@ -303,6 +304,7 @@ func transitionSaveConflict(ctx *transitionContext, result any) (router.Screen,
 		Config:        ctx.state.Config,
 		Host:          ctx.state.Host,
 		ResolvedItems: r.AllItems,
+		SessionID:     r.SessionID,
 	}
 }
 

internal/fileutil/fileutil.go

@@ -3,6 +3,7 @@ package fileutil
 import (
 	"archive/zip"
 	"bufio"
+	"crypto/md5"
 	"crypto/sha1"
 	"fmt"
 	"hash/crc32"
@@ -305,6 +306,25 @@ func FilterHiddenDirectories(entries []os.DirEntry) []os.DirEntry {
 	return result
 }
 
+// ComputeMD5 computes the MD5 hash of a file and returns it as a lowercase hex string.
+// This matches the server's content hash algorithm (8192-byte chunks, md5, hex output).
+func ComputeMD5(filePath string) (string, error) {
+	file, err := os.Open(filePath)
+	if err != nil {
+		return "", fmt.Errorf("failed to open file: %w", err)
+	}
+	defer file.Close()
+
+	hash := md5.New()
+	buffer := make([]byte, 8192)
+
+	if _, err := io.CopyBuffer(hash, file, buffer); err != nil {
+		return "", fmt.Errorf("failed to compute hash: %w", err)
+	}
+
+	return fmt.Sprintf("%x", hash.Sum(nil)), nil
+}
+
 // ComputeCRC32 computes the CRC32 hash of a file and returns it as an uppercase hex string
 func ComputeCRC32(filePath string) (string, error) {
 	file, err := os.Open(filePath)

romm/endpoints.go

@@ -28,8 +28,9 @@ const (
 	endpointSaveByID       = "/api/saves/%d"
 	endpointSaveSummary    = "/api/saves/summary"
 	endpointSaveContent    = "/api/saves/%d/content"
-	endpointSaveDownloaded = "/api/saves/%d/downloaded"
+	endpointDevices        = "/api/devices"
+	endpointDeviceByID     = "/api/devices/%s"
 
-	endpointDevices    = "/api/devices"
-	endpointDeviceByID = "/api/devices/%s"
+	endpointSyncNegotiate       = "/api/sync/negotiate"
+	endpointSyncSessionComplete = "/api/sync/sessions/%d/complete"
 )

romm/saves.go

@@ -87,6 +87,7 @@ type UploadSaveQuery struct {
 	Overwrite        bool   `qs:"overwrite,omitempty"`
 	Autocleanup      bool   `qs:"autocleanup,omitempty"`
 	AutocleanupLimit int    `qs:"autocleanup_limit,omitempty"`
+	SessionID        int    `qs:"session_id,omitempty"`
 }
 
 func (uq UploadSaveQuery) Valid() bool {
@@ -96,16 +97,13 @@ func (uq UploadSaveQuery) Valid() bool {
 type SaveContentQuery struct {
 	DeviceID   string `qs:"device_id,omitempty"`
 	Optimistic bool   `qs:"optimistic,omitempty"`
+	SessionID  int    `qs:"session_id,omitempty"`
 }
 
 func (scq SaveContentQuery) Valid() bool {
 	return scq.DeviceID != ""
 }
 
-type SaveDeviceBody struct {
-	DeviceID string `json:"device_id"`
-}
-
 type SaveSummaryQuery struct {
 	RomID int `qs:"rom_id"`
 }
@@ -124,26 +122,18 @@ func (c *Client) DownloadSave(downloadPath string) ([]byte, error) {
 	return c.doRequestRaw("GET", downloadPath, nil)
 }
 
-func (c *Client) DownloadSaveByID(saveID int, deviceID string, optimistic bool) ([]byte, error) {
+func (c *Client) DownloadSaveByID(saveID int, deviceID string, optimistic bool, sessionID ...int) ([]byte, error) {
 	path := fmt.Sprintf(endpointSaveContent, saveID)
 	query := SaveContentQuery{
 		DeviceID:   deviceID,
 		Optimistic: optimistic,
 	}
+	if len(sessionID) > 0 {
+		query.SessionID = sessionID[0]
+	}
 	return c.doRequestRawWithQuery("GET", path, query)
 }
 
-func (c *Client) ConfirmSaveDownloaded(saveID int, deviceID string) error {
-	path := fmt.Sprintf(endpointSaveDownloaded, saveID)
-	body := SaveDeviceBody{DeviceID: deviceID}
-	return c.doRequest("POST", path, nil, body, nil)
-}
-
-// MarkDeviceSynced confirms this device has the latest save state.
-// Used after both uploads and downloads.
-func (c *Client) MarkDeviceSynced(saveID int, deviceID string) error {
-	return c.ConfirmSaveDownloaded(saveID, deviceID)
-}
 
 func (c *Client) GetSaveSummary(romID int) (SaveSummary, error) {
 	var summary SaveSummary
@@ -187,13 +177,6 @@ func (c *Client) UpdateSave(saveID int, savePath string) (Save, error) {
 	return res, nil
 }
 
-func (c *Client) UploadSave(romID int, savePath string, emulator string) (Save, error) {
-	return c.UploadSaveWithQuery(UploadSaveQuery{
-		RomID:    romID,
-		Emulator: emulator,
-	}, savePath)
-}
-
 func (c *Client) UploadSaveWithQuery(query UploadSaveQuery, savePath string) (Save, error) {
 	file, err := os.Open(savePath)
 	if err != nil {

romm/sync.go

@@ -0,0 +1,81 @@
+package romm
+
+import (
+	"fmt"
+	"time"
+)
+
+// ClientSaveState represents the state of a single save file on the client device.
+type ClientSaveState struct {
+	RomID         int       `json:"rom_id"`
+	FileName      string    `json:"file_name"`
+	Slot          string    `json:"slot,omitempty"`
+	Emulator      string    `json:"emulator,omitempty"`
+	ContentHash   string    `json:"content_hash,omitempty"`
+	UpdatedAt     time.Time `json:"updated_at"`
+	FileSizeBytes int64     `json:"file_size_bytes"`
+}
+
+// SyncNegotiatePayload is the request body for POST /api/sync/negotiate.
+type SyncNegotiatePayload struct {
+	DeviceID string            `json:"device_id"`
+	Saves    []ClientSaveState `json:"saves"`
+}
+
+// SyncOperationSchema describes a single sync operation returned by the server.
+type SyncOperationSchema struct {
+	Action            string     `json:"action"` // "upload", "download", "conflict", "no_op"
+	RomID             int        `json:"rom_id"`
+	SaveID            *int       `json:"save_id"` // nil for new uploads
+	FileName          string     `json:"file_name"`
+	Slot              *string    `json:"slot,omitempty"`
+	Emulator          string     `json:"emulator,omitempty"`
+	Reason            string     `json:"reason"`
+	ServerUpdatedAt   *time.Time `json:"server_updated_at,omitempty"`
+	ServerContentHash *string    `json:"server_content_hash,omitempty"`
+}
+
+// SyncNegotiateResponse is the response from POST /api/sync/negotiate.
+type SyncNegotiateResponse struct {
+	SessionID     int                   `json:"session_id"`
+	Operations    []SyncOperationSchema `json:"operations"`
+	TotalUpload   int                   `json:"total_upload"`
+	TotalDownload int                   `json:"total_download"`
+	TotalConflict int                   `json:"total_conflict"`
+	TotalNoOp     int                   `json:"total_no_op"`
+}
+
+// SyncCompletePayload is the request body for POST /api/sync/sessions/{id}/complete.
+type SyncCompletePayload struct {
+	OperationsCompleted int `json:"operations_completed"`
+	OperationsFailed    int `json:"operations_failed"`
+}
+
+// SyncSessionSchema is the response from sync session endpoints.
+type SyncSessionSchema struct {
+	ID                  int        `json:"id"`
+	DeviceID            string     `json:"device_id"`
+	UserID              int        `json:"user_id"`
+	Status              string     `json:"status"`
+	InitiatedAt         time.Time  `json:"initiated_at"`
+	CompletedAt         *time.Time `json:"completed_at,omitempty"`
+	OperationsPlanned   int        `json:"operations_planned"`
+	OperationsCompleted int        `json:"operations_completed"`
+	OperationsFailed    int        `json:"operations_failed"`
+	ErrorMessage        *string    `json:"error_message,omitempty"`
+	CreatedAt           time.Time  `json:"created_at"`
+	UpdatedAt           time.Time  `json:"updated_at"`
+}
+
+// Negotiate sends the client's save state to the server and receives sync operations.
+func (c *Client) Negotiate(payload SyncNegotiatePayload) (SyncNegotiateResponse, error) {
+	var resp SyncNegotiateResponse
+	err := c.doRequest("POST", endpointSyncNegotiate, nil, payload, &resp)
+	return resp, err
+}
+
+// CompleteSession marks a sync session as completed.
+func (c *Client) CompleteSession(sessionID int, payload SyncCompletePayload) error {
+	path := fmt.Sprintf(endpointSyncSessionComplete, sessionID)
+	return c.doRequest("POST", path, nil, payload, nil)
+}