Implement Phase 4: gRPC sync service

- Proto definitions (engpad.v1.EngPadSync) with 6 RPCs - Generated Go gRPC code - Auth interceptor: username/password from metadata - SyncNotebook: upsert with full page/stroke replacement in a tx - DeleteNotebook, ListNotebooks handlers - Share link RPCs: CreateShareLink, RevokeShareLink, ListShareLinks - Share link token management (32-byte random, optional expiry) - gRPC server with TLS 1.3 Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 19:52:47 -07:00
parent 846a6fe42d
commit 7d4e52ae92
10 changed files with 1912 additions and 2 deletions
--- a/gen/engpad/v1/sync.pb.go
+++ b/gen/engpad/v1/sync.pb.go
--- a/gen/engpad/v1/sync_grpc.pb.go
+++ b/gen/engpad/v1/sync_grpc.pb.go
@@ -0,0 +1,311 @@
+// Code generated by protoc-gen-go-grpc. DO NOT EDIT.
+// versions:
+// - protoc-gen-go-grpc v1.6.1
+// - protoc             v3.20.3
+// source: engpad/v1/sync.proto
+
+package engpadv1
+
+import (
+	context "context"
+	grpc "google.golang.org/grpc"
+	codes "google.golang.org/grpc/codes"
+	status "google.golang.org/grpc/status"
+)
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the grpc package it is being compiled against.
+// Requires gRPC-Go v1.64.0 or later.
+const _ = grpc.SupportPackageIsVersion9
+
+const (
+	EngPadSync_SyncNotebook_FullMethodName    = "/engpad.v1.EngPadSync/SyncNotebook"
+	EngPadSync_DeleteNotebook_FullMethodName  = "/engpad.v1.EngPadSync/DeleteNotebook"
+	EngPadSync_ListNotebooks_FullMethodName   = "/engpad.v1.EngPadSync/ListNotebooks"
+	EngPadSync_CreateShareLink_FullMethodName = "/engpad.v1.EngPadSync/CreateShareLink"
+	EngPadSync_RevokeShareLink_FullMethodName = "/engpad.v1.EngPadSync/RevokeShareLink"
+	EngPadSync_ListShareLinks_FullMethodName  = "/engpad.v1.EngPadSync/ListShareLinks"
+)
+
+// EngPadSyncClient is the client API for EngPadSync service.
+//
+// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://pkg.go.dev/google.golang.org/grpc/?tab=doc#ClientConn.NewStream.
+type EngPadSyncClient interface {
+	SyncNotebook(ctx context.Context, in *SyncNotebookRequest, opts ...grpc.CallOption) (*SyncNotebookResponse, error)
+	DeleteNotebook(ctx context.Context, in *DeleteNotebookRequest, opts ...grpc.CallOption) (*DeleteNotebookResponse, error)
+	ListNotebooks(ctx context.Context, in *ListNotebooksRequest, opts ...grpc.CallOption) (*ListNotebooksResponse, error)
+	CreateShareLink(ctx context.Context, in *CreateShareLinkRequest, opts ...grpc.CallOption) (*CreateShareLinkResponse, error)
+	RevokeShareLink(ctx context.Context, in *RevokeShareLinkRequest, opts ...grpc.CallOption) (*RevokeShareLinkResponse, error)
+	ListShareLinks(ctx context.Context, in *ListShareLinksRequest, opts ...grpc.CallOption) (*ListShareLinksResponse, error)
+}
+
+type engPadSyncClient struct {
+	cc grpc.ClientConnInterface
+}
+
+func NewEngPadSyncClient(cc grpc.ClientConnInterface) EngPadSyncClient {
+	return &engPadSyncClient{cc}
+}
+
+func (c *engPadSyncClient) SyncNotebook(ctx context.Context, in *SyncNotebookRequest, opts ...grpc.CallOption) (*SyncNotebookResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(SyncNotebookResponse)
+	err := c.cc.Invoke(ctx, EngPadSync_SyncNotebook_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *engPadSyncClient) DeleteNotebook(ctx context.Context, in *DeleteNotebookRequest, opts ...grpc.CallOption) (*DeleteNotebookResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(DeleteNotebookResponse)
+	err := c.cc.Invoke(ctx, EngPadSync_DeleteNotebook_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *engPadSyncClient) ListNotebooks(ctx context.Context, in *ListNotebooksRequest, opts ...grpc.CallOption) (*ListNotebooksResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(ListNotebooksResponse)
+	err := c.cc.Invoke(ctx, EngPadSync_ListNotebooks_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *engPadSyncClient) CreateShareLink(ctx context.Context, in *CreateShareLinkRequest, opts ...grpc.CallOption) (*CreateShareLinkResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(CreateShareLinkResponse)
+	err := c.cc.Invoke(ctx, EngPadSync_CreateShareLink_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *engPadSyncClient) RevokeShareLink(ctx context.Context, in *RevokeShareLinkRequest, opts ...grpc.CallOption) (*RevokeShareLinkResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(RevokeShareLinkResponse)
+	err := c.cc.Invoke(ctx, EngPadSync_RevokeShareLink_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *engPadSyncClient) ListShareLinks(ctx context.Context, in *ListShareLinksRequest, opts ...grpc.CallOption) (*ListShareLinksResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(ListShareLinksResponse)
+	err := c.cc.Invoke(ctx, EngPadSync_ListShareLinks_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+// EngPadSyncServer is the server API for EngPadSync service.
+// All implementations must embed UnimplementedEngPadSyncServer
+// for forward compatibility.
+type EngPadSyncServer interface {
+	SyncNotebook(context.Context, *SyncNotebookRequest) (*SyncNotebookResponse, error)
+	DeleteNotebook(context.Context, *DeleteNotebookRequest) (*DeleteNotebookResponse, error)
+	ListNotebooks(context.Context, *ListNotebooksRequest) (*ListNotebooksResponse, error)
+	CreateShareLink(context.Context, *CreateShareLinkRequest) (*CreateShareLinkResponse, error)
+	RevokeShareLink(context.Context, *RevokeShareLinkRequest) (*RevokeShareLinkResponse, error)
+	ListShareLinks(context.Context, *ListShareLinksRequest) (*ListShareLinksResponse, error)
+	mustEmbedUnimplementedEngPadSyncServer()
+}
+
+// UnimplementedEngPadSyncServer must be embedded to have
+// forward compatible implementations.
+//
+// NOTE: this should be embedded by value instead of pointer to avoid a nil
+// pointer dereference when methods are called.
+type UnimplementedEngPadSyncServer struct{}
+
+func (UnimplementedEngPadSyncServer) SyncNotebook(context.Context, *SyncNotebookRequest) (*SyncNotebookResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method SyncNotebook not implemented")
+}
+func (UnimplementedEngPadSyncServer) DeleteNotebook(context.Context, *DeleteNotebookRequest) (*DeleteNotebookResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method DeleteNotebook not implemented")
+}
+func (UnimplementedEngPadSyncServer) ListNotebooks(context.Context, *ListNotebooksRequest) (*ListNotebooksResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method ListNotebooks not implemented")
+}
+func (UnimplementedEngPadSyncServer) CreateShareLink(context.Context, *CreateShareLinkRequest) (*CreateShareLinkResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method CreateShareLink not implemented")
+}
+func (UnimplementedEngPadSyncServer) RevokeShareLink(context.Context, *RevokeShareLinkRequest) (*RevokeShareLinkResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method RevokeShareLink not implemented")
+}
+func (UnimplementedEngPadSyncServer) ListShareLinks(context.Context, *ListShareLinksRequest) (*ListShareLinksResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method ListShareLinks not implemented")
+}
+func (UnimplementedEngPadSyncServer) mustEmbedUnimplementedEngPadSyncServer() {}
+func (UnimplementedEngPadSyncServer) testEmbeddedByValue()                    {}
+
+// UnsafeEngPadSyncServer may be embedded to opt out of forward compatibility for this service.
+// Use of this interface is not recommended, as added methods to EngPadSyncServer will
+// result in compilation errors.
+type UnsafeEngPadSyncServer interface {
+	mustEmbedUnimplementedEngPadSyncServer()
+}
+
+func RegisterEngPadSyncServer(s grpc.ServiceRegistrar, srv EngPadSyncServer) {
+	// If the following call panics, it indicates UnimplementedEngPadSyncServer was
+	// embedded by pointer and is nil.  This will cause panics if an
+	// unimplemented method is ever invoked, so we test this at initialization
+	// time to prevent it from happening at runtime later due to I/O.
+	if t, ok := srv.(interface{ testEmbeddedByValue() }); ok {
+		t.testEmbeddedByValue()
+	}
+	s.RegisterService(&EngPadSync_ServiceDesc, srv)
+}
+
+func _EngPadSync_SyncNotebook_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(SyncNotebookRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(EngPadSyncServer).SyncNotebook(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: EngPadSync_SyncNotebook_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(EngPadSyncServer).SyncNotebook(ctx, req.(*SyncNotebookRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _EngPadSync_DeleteNotebook_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(DeleteNotebookRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(EngPadSyncServer).DeleteNotebook(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: EngPadSync_DeleteNotebook_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(EngPadSyncServer).DeleteNotebook(ctx, req.(*DeleteNotebookRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _EngPadSync_ListNotebooks_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(ListNotebooksRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(EngPadSyncServer).ListNotebooks(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: EngPadSync_ListNotebooks_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(EngPadSyncServer).ListNotebooks(ctx, req.(*ListNotebooksRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _EngPadSync_CreateShareLink_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(CreateShareLinkRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(EngPadSyncServer).CreateShareLink(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: EngPadSync_CreateShareLink_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(EngPadSyncServer).CreateShareLink(ctx, req.(*CreateShareLinkRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _EngPadSync_RevokeShareLink_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(RevokeShareLinkRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(EngPadSyncServer).RevokeShareLink(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: EngPadSync_RevokeShareLink_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(EngPadSyncServer).RevokeShareLink(ctx, req.(*RevokeShareLinkRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _EngPadSync_ListShareLinks_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(ListShareLinksRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(EngPadSyncServer).ListShareLinks(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: EngPadSync_ListShareLinks_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(EngPadSyncServer).ListShareLinks(ctx, req.(*ListShareLinksRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+// EngPadSync_ServiceDesc is the grpc.ServiceDesc for EngPadSync service.
+// It's only intended for direct use with grpc.RegisterService,
+// and not to be introspected or modified (even as a copy)
+var EngPadSync_ServiceDesc = grpc.ServiceDesc{
+	ServiceName: "engpad.v1.EngPadSync",
+	HandlerType: (*EngPadSyncServer)(nil),
+	Methods: []grpc.MethodDesc{
+		{
+			MethodName: "SyncNotebook",
+			Handler:    _EngPadSync_SyncNotebook_Handler,
+		},
+		{
+			MethodName: "DeleteNotebook",
+			Handler:    _EngPadSync_DeleteNotebook_Handler,
+		},
+		{
+			MethodName: "ListNotebooks",
+			Handler:    _EngPadSync_ListNotebooks_Handler,
+		},
+		{
+			MethodName: "CreateShareLink",
+			Handler:    _EngPadSync_CreateShareLink_Handler,
+		},
+		{
+			MethodName: "RevokeShareLink",
+			Handler:    _EngPadSync_RevokeShareLink_Handler,
+		},
+		{
+			MethodName: "ListShareLinks",
+			Handler:    _EngPadSync_ListShareLinks_Handler,
+		},
+	},
+	Streams:  []grpc.StreamDesc{},
+	Metadata: "engpad/v1/sync.proto",
+}
--- a/go.mod
+++ b/go.mod
@@ -7,6 +7,8 @@ require (
 	github.com/spf13/cobra v1.10.2
 	golang.org/x/crypto v0.49.0
 	golang.org/x/term v0.41.0
+	google.golang.org/grpc v1.79.3
+	google.golang.org/protobuf v1.36.11
 	modernc.org/sqlite v1.47.0
 )

@@ -18,7 +20,10 @@ require (
 	github.com/ncruces/go-strftime v1.0.0 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
 	github.com/spf13/pflag v1.0.9 // indirect
+	golang.org/x/net v0.51.0 // indirect
 	golang.org/x/sys v0.42.0 // indirect
+	golang.org/x/text v0.35.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 // indirect
 	modernc.org/libc v1.70.0 // indirect
 	modernc.org/mathutil v1.7.1 // indirect
 	modernc.org/memory v1.11.0 // indirect
--- a/go.sum
+++ b/go.sum
@@ -1,6 +1,16 @@
+github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
+github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=
+github.com/go-logr/logr v1.4.3/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
+github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
+github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
+github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
+github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
+github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
 github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e h1:ijClszYn+mADRFY17kjQEVQ1XRhq2/JR1M3sGqeJoxs=
 github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e/go.mod h1:boTsfXsheKC2y+lKOCMpSfarhxDeIzfZG1jqGcPl3cA=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
@@ -22,20 +32,44 @@ github.com/spf13/cobra v1.10.2 h1:DMTTonx5m65Ic0GOoRY2c16WCbHxOOw6xxezuLaBpcU=
 github.com/spf13/cobra v1.10.2/go.mod h1:7C1pvHqHw5A4vrJfjNwvOdzYu0Gml16OCs2GRiTUUS4=
 github.com/spf13/pflag v1.0.9 h1:9exaQaMOCwffKiiiYk6/BndUBv+iRViNW+4lEMi0PvY=
 github.com/spf13/pflag v1.0.9/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+go.opentelemetry.io/auto/sdk v1.2.1 h1:jXsnJ4Lmnqd11kwkBV2LgLoFMZKizbCi5fNZ/ipaZ64=
+go.opentelemetry.io/auto/sdk v1.2.1/go.mod h1:KRTj+aOaElaLi+wW1kO/DZRXwkF4C5xPbEe3ZiIhN7Y=
+go.opentelemetry.io/otel v1.39.0 h1:8yPrr/S0ND9QEfTfdP9V+SiwT4E0G7Y5MO7p85nis48=
+go.opentelemetry.io/otel v1.39.0/go.mod h1:kLlFTywNWrFyEdH0oj2xK0bFYZtHRYUdv1NklR/tgc8=
+go.opentelemetry.io/otel/metric v1.39.0 h1:d1UzonvEZriVfpNKEVmHXbdf909uGTOQjA0HF0Ls5Q0=
+go.opentelemetry.io/otel/metric v1.39.0/go.mod h1:jrZSWL33sD7bBxg1xjrqyDjnuzTUB0x1nBERXd7Ftcs=
+go.opentelemetry.io/otel/sdk v1.39.0 h1:nMLYcjVsvdui1B/4FRkwjzoRVsMK8uL/cj0OyhKzt18=
+go.opentelemetry.io/otel/sdk v1.39.0/go.mod h1:vDojkC4/jsTJsE+kh+LXYQlbL8CgrEcwmt1ENZszdJE=
+go.opentelemetry.io/otel/sdk/metric v1.39.0 h1:cXMVVFVgsIf2YL6QkRF4Urbr/aMInf+2WKg+sEJTtB8=
+go.opentelemetry.io/otel/sdk/metric v1.39.0/go.mod h1:xq9HEVH7qeX69/JnwEfp6fVq5wosJsY1mt4lLfYdVew=
+go.opentelemetry.io/otel/trace v1.39.0 h1:2d2vfpEDmCJ5zVYz7ijaJdOF59xLomrvj7bjt6/qCJI=
+go.opentelemetry.io/otel/trace v1.39.0/go.mod h1:88w4/PnZSazkGzz/w84VHpQafiU4EtqqlVdxWy+rNOA=
 go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
 golang.org/x/crypto v0.49.0 h1:+Ng2ULVvLHnJ/ZFEq4KdcDd/cfjrrjjNSXNzxg0Y4U4=
 golang.org/x/crypto v0.49.0/go.mod h1:ErX4dUh2UM+CFYiXZRTcMpEcN8b/1gxEuv3nODoYtCA=
 golang.org/x/mod v0.33.0 h1:tHFzIWbBifEmbwtGz65eaWyGiGZatSrT9prnU8DbVL8=
 golang.org/x/mod v0.33.0/go.mod h1:swjeQEj+6r7fODbD2cqrnje9PnziFuw4bmLbBZFrQ5w=
-golang.org/x/sync v0.19.0 h1:vV+1eWNmZ5geRlYjzm2adRgW2/mcpevXNg50YZtPCE4=
-golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
+golang.org/x/net v0.51.0 h1:94R/GTO7mt3/4wIKpcR5gkGmRLOuE/2hNGeWq/GBIFo=
+golang.org/x/net v0.51.0/go.mod h1:aamm+2QF5ogm02fjy5Bb7CQ0WMt1/WVM7FtyaTLlA9Y=
+golang.org/x/sync v0.20.0 h1:e0PTpb7pjO8GAtTs2dQ6jYa5BWYlMuX047Dco/pItO4=
+golang.org/x/sync v0.20.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.42.0 h1:omrd2nAlyT5ESRdCLYdm3+fMfNFE/+Rf4bDIQImRJeo=
 golang.org/x/sys v0.42.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
 golang.org/x/term v0.41.0 h1:QCgPso/Q3RTJx2Th4bDLqML4W6iJiaXFq2/ftQF13YU=
 golang.org/x/term v0.41.0/go.mod h1:3pfBgksrReYfZ5lvYM0kSO0LIkAl4Yl2bXOkKP7Ec2A=
+golang.org/x/text v0.35.0 h1:JOVx6vVDFokkpaq1AEptVzLTpDe9KGpj5tR4/X+ybL8=
+golang.org/x/text v0.35.0/go.mod h1:khi/HExzZJ2pGnjenulevKNX1W67CUy0AsXcNubPGCA=
 golang.org/x/tools v0.42.0 h1:uNgphsn75Tdz5Ji2q36v/nsFSfR/9BRFvqhGBaJGd5k=
 golang.org/x/tools v0.42.0/go.mod h1:Ma6lCIwGZvHK6XtgbswSoWroEkhugApmsXyrUmBhfr0=
+gonum.org/v1/gonum v0.16.0 h1:5+ul4Swaf3ESvrOnidPp4GZbzf0mxVQpDCYUQE7OJfk=
+gonum.org/v1/gonum v0.16.0/go.mod h1:fef3am4MQ93R2HHpKnLk4/Tbh/s0+wqD5nfa6Pnwy4E=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 h1:gRkg/vSppuSQoDjxyiGfN4Upv/h/DQmIR10ZU8dh4Ww=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217/go.mod h1:7i2o+ce6H/6BluujYR+kqX3GKH+dChPTQU19wjRPiGk=
+google.golang.org/grpc v1.79.3 h1:sybAEdRIEtvcD68Gx7dmnwjZKlyfuc61Dyo9pGXXkKE=
+google.golang.org/grpc v1.79.3/go.mod h1:KmT0Kjez+0dde/v2j9vzwoAScgEPx/Bw1CYChhHLrHQ=
+google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
+google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 modernc.org/cc/v4 v4.27.1 h1:9W30zRlYrefrDV2JE2O8VDtJ1yPGownxciz5rrbQZis=
 modernc.org/cc/v4 v4.27.1/go.mod h1:uVtb5OGqUKpoLWhqwNQo/8LwvoiEBLvZXIQ/SmO6mL0=
--- a/internal/grpcserver/interceptors.go
+++ b/internal/grpcserver/interceptors.go
@@ -0,0 +1,46 @@
+package grpcserver
+
+import (
+	"context"
+	"database/sql"
+
+	"git.wntrmute.dev/kyle/eng-pad-server/internal/auth"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/status"
+)
+
+type contextKey string
+
+const userIDKey contextKey = "user_id"
+
+// UserIDFromContext extracts the authenticated user ID from the context.
+func UserIDFromContext(ctx context.Context) (int64, bool) {
+	id, ok := ctx.Value(userIDKey).(int64)
+	return id, ok
+}
+
+// AuthInterceptor verifies username/password from gRPC metadata.
+func AuthInterceptor(database *sql.DB) grpc.UnaryServerInterceptor {
+	return func(ctx context.Context, req any, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (any, error) {
+		md, ok := metadata.FromIncomingContext(ctx)
+		if !ok {
+			return nil, status.Error(codes.Unauthenticated, "missing metadata")
+		}
+
+		usernames := md.Get("username")
+		passwords := md.Get("password")
+		if len(usernames) == 0 || len(passwords) == 0 {
+			return nil, status.Error(codes.Unauthenticated, "missing credentials")
+		}
+
+		userID, err := auth.AuthenticateUser(database, usernames[0], passwords[0])
+		if err != nil {
+			return nil, status.Error(codes.Unauthenticated, "invalid credentials")
+		}
+
+		ctx = context.WithValue(ctx, userIDKey, userID)
+		return handler(ctx, req)
+	}
+}
--- a/internal/grpcserver/server.go
+++ b/internal/grpcserver/server.go
@@ -0,0 +1,48 @@
+package grpcserver
+
+import (
+	"crypto/tls"
+	"database/sql"
+	"fmt"
+	"net"
+
+	pb "git.wntrmute.dev/kyle/eng-pad-server/gen/engpad/v1"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials"
+)
+
+type Config struct {
+	Addr    string
+	TLSCert string
+	TLSKey  string
+	DB      *sql.DB
+	BaseURL string
+}
+
+func Start(cfg Config) error {
+	cert, err := tls.LoadX509KeyPair(cfg.TLSCert, cfg.TLSKey)
+	if err != nil {
+		return fmt.Errorf("load TLS cert: %w", err)
+	}
+
+	tlsConfig := &tls.Config{
+		Certificates: []tls.Certificate{cert},
+		MinVersion:   tls.VersionTLS13,
+	}
+
+	lis, err := net.Listen("tcp", cfg.Addr)
+	if err != nil {
+		return fmt.Errorf("listen %s: %w", cfg.Addr, err)
+	}
+
+	srv := grpc.NewServer(
+		grpc.Creds(credentials.NewTLS(tlsConfig)),
+		grpc.UnaryInterceptor(AuthInterceptor(cfg.DB)),
+	)
+
+	syncSvc := &SyncService{DB: cfg.DB, BaseURL: cfg.BaseURL}
+	pb.RegisterEngPadSyncServer(srv, syncSvc)
+
+	fmt.Printf("gRPC listening on %s\n", cfg.Addr)
+	return srv.Serve(lis)
+}
--- a/internal/grpcserver/share.go
+++ b/internal/grpcserver/share.go
@@ -0,0 +1,94 @@
+package grpcserver
+
+import (
+	"context"
+	"database/sql"
+	"time"
+
+	pb "git.wntrmute.dev/kyle/eng-pad-server/gen/engpad/v1"
+	"git.wntrmute.dev/kyle/eng-pad-server/internal/share"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/types/known/timestamppb"
+)
+
+func (s *SyncService) CreateShareLink(ctx context.Context, req *pb.CreateShareLinkRequest) (*pb.CreateShareLinkResponse, error) {
+	userID, ok := UserIDFromContext(ctx)
+	if !ok {
+		return nil, status.Error(codes.Internal, "missing user context")
+	}
+
+	// Verify notebook belongs to user
+	var notebookID int64
+	err := s.DB.QueryRowContext(ctx,
+		"SELECT id FROM notebooks WHERE user_id = ? AND remote_id = ?",
+		userID, req.NotebookId,
+	).Scan(&notebookID)
+	if err == sql.ErrNoRows {
+		return nil, status.Error(codes.NotFound, "notebook not found")
+	} else if err != nil {
+		return nil, status.Errorf(codes.Internal, "query: %v", err)
+	}
+
+	var expiry time.Duration
+	if req.ExpiresInSeconds > 0 {
+		expiry = time.Duration(req.ExpiresInSeconds) * time.Second
+	}
+
+	token, expiresAt, err := share.CreateLink(s.DB, notebookID, expiry, s.BaseURL)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "create link: %v", err)
+	}
+
+	resp := &pb.CreateShareLinkResponse{
+		Token: token,
+		Url:   s.BaseURL + "/s/" + token,
+	}
+	if expiresAt != nil {
+		resp.ExpiresAt = timestamppb.New(*expiresAt)
+	}
+	return resp, nil
+}
+
+func (s *SyncService) RevokeShareLink(ctx context.Context, req *pb.RevokeShareLinkRequest) (*pb.RevokeShareLinkResponse, error) {
+	if err := share.RevokeLink(s.DB, req.Token); err != nil {
+		return nil, status.Errorf(codes.Internal, "revoke: %v", err)
+	}
+	return &pb.RevokeShareLinkResponse{}, nil
+}
+
+func (s *SyncService) ListShareLinks(ctx context.Context, req *pb.ListShareLinksRequest) (*pb.ListShareLinksResponse, error) {
+	userID, ok := UserIDFromContext(ctx)
+	if !ok {
+		return nil, status.Error(codes.Internal, "missing user context")
+	}
+
+	var notebookID int64
+	err := s.DB.QueryRowContext(ctx,
+		"SELECT id FROM notebooks WHERE user_id = ? AND remote_id = ?",
+		userID, req.NotebookId,
+	).Scan(&notebookID)
+	if err != nil {
+		return nil, status.Error(codes.NotFound, "notebook not found")
+	}
+
+	links, err := share.ListLinks(s.DB, notebookID, s.BaseURL)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "list: %v", err)
+	}
+
+	var pbLinks []*pb.ShareLinkInfo
+	for _, l := range links {
+		pbl := &pb.ShareLinkInfo{
+			Token:     l.Token,
+			Url:       l.URL,
+			CreatedAt: timestamppb.New(l.CreatedAt),
+		}
+		if l.ExpiresAt != nil {
+			pbl.ExpiresAt = timestamppb.New(*l.ExpiresAt)
+		}
+		pbLinks = append(pbLinks, pbl)
+	}
+
+	return &pb.ListShareLinksResponse{Links: pbLinks}, nil
+}
--- a/internal/grpcserver/sync.go
+++ b/internal/grpcserver/sync.go
@@ -0,0 +1,142 @@
+package grpcserver
+
+import (
+	"context"
+	"database/sql"
+	"time"
+
+	pb "git.wntrmute.dev/kyle/eng-pad-server/gen/engpad/v1"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/types/known/timestamppb"
+)
+
+type SyncService struct {
+	pb.UnimplementedEngPadSyncServer
+	DB      *sql.DB
+	BaseURL string
+}
+
+func (s *SyncService) SyncNotebook(ctx context.Context, req *pb.SyncNotebookRequest) (*pb.SyncNotebookResponse, error) {
+	userID, ok := UserIDFromContext(ctx)
+	if !ok {
+		return nil, status.Error(codes.Internal, "missing user context")
+	}
+
+	tx, err := s.DB.BeginTx(ctx, nil)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "begin tx: %v", err)
+	}
+	defer func() { _ = tx.Rollback() }()
+
+	now := time.Now().UnixMilli()
+
+	// Upsert notebook
+	var notebookID int64
+	err = tx.QueryRowContext(ctx,
+		"SELECT id FROM notebooks WHERE user_id = ? AND remote_id = ?",
+		userID, req.NotebookId,
+	).Scan(&notebookID)
+
+	if err == sql.ErrNoRows {
+		res, err := tx.ExecContext(ctx,
+			"INSERT INTO notebooks (user_id, remote_id, title, page_size, synced_at) VALUES (?, ?, ?, ?, ?)",
+			userID, req.NotebookId, req.Title, req.PageSize, now,
+		)
+		if err != nil {
+			return nil, status.Errorf(codes.Internal, "insert notebook: %v", err)
+		}
+		notebookID, _ = res.LastInsertId()
+	} else if err != nil {
+		return nil, status.Errorf(codes.Internal, "query notebook: %v", err)
+	} else {
+		// Update existing — delete all pages (cascade deletes strokes)
+		if _, err := tx.ExecContext(ctx, "DELETE FROM pages WHERE notebook_id = ?", notebookID); err != nil {
+			return nil, status.Errorf(codes.Internal, "delete pages: %v", err)
+		}
+		if _, err := tx.ExecContext(ctx,
+			"UPDATE notebooks SET title = ?, page_size = ?, synced_at = ? WHERE id = ?",
+			req.Title, req.PageSize, now, notebookID,
+		); err != nil {
+			return nil, status.Errorf(codes.Internal, "update notebook: %v", err)
+		}
+	}
+
+	// Insert pages and strokes
+	for _, page := range req.Pages {
+		res, err := tx.ExecContext(ctx,
+			"INSERT INTO pages (notebook_id, remote_id, page_number) VALUES (?, ?, ?)",
+			notebookID, page.PageId, page.PageNumber,
+		)
+		if err != nil {
+			return nil, status.Errorf(codes.Internal, "insert page: %v", err)
+		}
+		pageID, _ := res.LastInsertId()
+
+		for _, stroke := range page.Strokes {
+			if _, err := tx.ExecContext(ctx,
+				"INSERT INTO strokes (page_id, pen_size, color, style, point_data, stroke_order) VALUES (?, ?, ?, ?, ?, ?)",
+				pageID, stroke.PenSize, stroke.Color, stroke.Style, stroke.PointData, stroke.StrokeOrder,
+			); err != nil {
+				return nil, status.Errorf(codes.Internal, "insert stroke: %v", err)
+			}
+		}
+	}
+
+	if err := tx.Commit(); err != nil {
+		return nil, status.Errorf(codes.Internal, "commit: %v", err)
+	}
+
+	return &pb.SyncNotebookResponse{
+		ServerNotebookId: notebookID,
+		SyncedAt:         timestamppb.Now(),
+	}, nil
+}
+
+func (s *SyncService) DeleteNotebook(ctx context.Context, req *pb.DeleteNotebookRequest) (*pb.DeleteNotebookResponse, error) {
+	userID, ok := UserIDFromContext(ctx)
+	if !ok {
+		return nil, status.Error(codes.Internal, "missing user context")
+	}
+
+	_, err := s.DB.ExecContext(ctx,
+		"DELETE FROM notebooks WHERE user_id = ? AND remote_id = ?",
+		userID, req.NotebookId,
+	)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "delete: %v", err)
+	}
+
+	return &pb.DeleteNotebookResponse{}, nil
+}
+
+func (s *SyncService) ListNotebooks(ctx context.Context, req *pb.ListNotebooksRequest) (*pb.ListNotebooksResponse, error) {
+	userID, ok := UserIDFromContext(ctx)
+	if !ok {
+		return nil, status.Error(codes.Internal, "missing user context")
+	}
+
+	rows, err := s.DB.QueryContext(ctx,
+		`SELECT n.id, n.remote_id, n.title, n.page_size, n.synced_at,
+		        (SELECT COUNT(*) FROM pages WHERE notebook_id = n.id) as page_count
+		 FROM notebooks n WHERE n.user_id = ? ORDER BY n.synced_at DESC`,
+		userID,
+	)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "query: %v", err)
+	}
+	defer func() { _ = rows.Close() }()
+
+	var notebooks []*pb.NotebookSummary
+	for rows.Next() {
+		var nb pb.NotebookSummary
+		var syncedAt int64
+		if err := rows.Scan(&nb.ServerId, &nb.RemoteId, &nb.Title, &nb.PageSize, &syncedAt, &nb.PageCount); err != nil {
+			return nil, status.Errorf(codes.Internal, "scan: %v", err)
+		}
+		nb.SyncedAt = timestamppb.New(time.UnixMilli(syncedAt))
+		notebooks = append(notebooks, &nb)
+	}
+
+	return &pb.ListNotebooksResponse{Notebooks: notebooks}, nil
+}
--- a/internal/share/share.go
+++ b/internal/share/share.go
@@ -0,0 +1,105 @@
+package share
+
+import (
+	"crypto/rand"
+	"database/sql"
+	"encoding/base64"
+	"fmt"
+	"time"
+)
+
+const tokenBytes = 32
+
+type LinkInfo struct {
+	Token     string
+	URL       string
+	CreatedAt time.Time
+	ExpiresAt *time.Time
+}
+
+// CreateLink generates a shareable link for a notebook.
+func CreateLink(database *sql.DB, notebookID int64, expiry time.Duration, baseURL string) (string, *time.Time, error) {
+	raw := make([]byte, tokenBytes)
+	if _, err := rand.Read(raw); err != nil {
+		return "", nil, fmt.Errorf("generate token: %w", err)
+	}
+
+	token := base64.URLEncoding.WithPadding(base64.NoPadding).EncodeToString(raw)
+	now := time.Now().UnixMilli()
+
+	var expiresAt *int64
+	var expiresTime *time.Time
+	if expiry > 0 {
+		ea := time.Now().Add(expiry).UnixMilli()
+		expiresAt = &ea
+		t := time.UnixMilli(ea)
+		expiresTime = &t
+	}
+
+	_, err := database.Exec(
+		"INSERT INTO share_links (notebook_id, token, expires_at, created_at) VALUES (?, ?, ?, ?)",
+		notebookID, token, expiresAt, now,
+	)
+	if err != nil {
+		return "", nil, fmt.Errorf("insert share link: %w", err)
+	}
+
+	return token, expiresTime, nil
+}
+
+// ValidateLink checks if a token is valid and returns the notebook ID.
+func ValidateLink(database *sql.DB, token string) (int64, error) {
+	var notebookID int64
+	var expiresAt *int64
+	err := database.QueryRow(
+		"SELECT notebook_id, expires_at FROM share_links WHERE token = ?", token,
+	).Scan(&notebookID, &expiresAt)
+	if err != nil {
+		return 0, fmt.Errorf("link not found")
+	}
+
+	if expiresAt != nil && time.Now().UnixMilli() > *expiresAt {
+		return 0, fmt.Errorf("link expired")
+	}
+
+	return notebookID, nil
+}
+
+// RevokeLink deletes a share link.
+func RevokeLink(database *sql.DB, token string) error {
+	_, err := database.Exec("DELETE FROM share_links WHERE token = ?", token)
+	return err
+}
+
+// ListLinks returns all active share links for a notebook.
+func ListLinks(database *sql.DB, notebookID int64, baseURL string) ([]LinkInfo, error) {
+	rows, err := database.Query(
+		"SELECT token, created_at, expires_at FROM share_links WHERE notebook_id = ? ORDER BY created_at DESC",
+		notebookID,
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = rows.Close() }()
+
+	var links []LinkInfo
+	for rows.Next() {
+		var token string
+		var createdAt int64
+		var expiresAt *int64
+		if err := rows.Scan(&token, &createdAt, &expiresAt); err != nil {
+			return nil, err
+		}
+		li := LinkInfo{
+			Token:     token,
+			URL:       baseURL + "/s/" + token,
+			CreatedAt: time.UnixMilli(createdAt),
+		}
+		if expiresAt != nil {
+			t := time.UnixMilli(*expiresAt)
+			li.ExpiresAt = &t
+		}
+		links = append(links, li)
+	}
+	return links, nil
+}
--- a/proto/engpad/v1/sync.proto
+++ b/proto/engpad/v1/sync.proto
@@ -0,0 +1,94 @@
+syntax = "proto3";
+package engpad.v1;
+
+option go_package = "git.wntrmute.dev/kyle/eng-pad-server/gen/engpad/v1;engpadv1";
+
+import "google/protobuf/timestamp.proto";
+
+service EngPadSync {
+    rpc SyncNotebook(SyncNotebookRequest) returns (SyncNotebookResponse);
+    rpc DeleteNotebook(DeleteNotebookRequest) returns (DeleteNotebookResponse);
+    rpc ListNotebooks(ListNotebooksRequest) returns (ListNotebooksResponse);
+    rpc CreateShareLink(CreateShareLinkRequest) returns (CreateShareLinkResponse);
+    rpc RevokeShareLink(RevokeShareLinkRequest) returns (RevokeShareLinkResponse);
+    rpc ListShareLinks(ListShareLinksRequest) returns (ListShareLinksResponse);
+}
+
+message SyncNotebookRequest {
+    int64 notebook_id = 1;
+    string title = 2;
+    string page_size = 3;
+    repeated PageData pages = 4;
+}
+
+message PageData {
+    int64 page_id = 1;
+    int32 page_number = 2;
+    repeated StrokeData strokes = 3;
+}
+
+message StrokeData {
+    float pen_size = 1;
+    int32 color = 2;
+    string style = 3;
+    bytes point_data = 4;
+    int32 stroke_order = 5;
+}
+
+message SyncNotebookResponse {
+    int64 server_notebook_id = 1;
+    google.protobuf.Timestamp synced_at = 2;
+}
+
+message DeleteNotebookRequest {
+    int64 notebook_id = 1;
+}
+
+message DeleteNotebookResponse {}
+
+message ListNotebooksRequest {}
+
+message ListNotebooksResponse {
+    repeated NotebookSummary notebooks = 1;
+}
+
+message NotebookSummary {
+    int64 server_id = 1;
+    int64 remote_id = 2;
+    string title = 3;
+    string page_size = 4;
+    int32 page_count = 5;
+    google.protobuf.Timestamp synced_at = 6;
+}
+
+message CreateShareLinkRequest {
+    int64 notebook_id = 1;
+    int64 expires_in_seconds = 2;
+}
+
+message CreateShareLinkResponse {
+    string token = 1;
+    string url = 2;
+    google.protobuf.Timestamp expires_at = 3;
+}
+
+message RevokeShareLinkRequest {
+    string token = 1;
+}
+
+message RevokeShareLinkResponse {}
+
+message ListShareLinksRequest {
+    int64 notebook_id = 1;
+}
+
+message ListShareLinksResponse {
+    repeated ShareLinkInfo links = 1;
+}
+
+message ShareLinkInfo {
+    string token = 1;
+    string url = 2;
+    google.protobuf.Timestamp created_at = 3;
+    google.protobuf.Timestamp expires_at = 4;
+}