feat(gateway): confirmEmailLink RPC + language on the email request + profile event

Add the confirm-link edge method (auth.email.confirm_link): a new
EmailConfirmLinkRequest/Result fbs table, the transcode const + handler + encoder,
and the backend-client call to the existing /sessions/email/confirm-link endpoint —
it rides Execute under the existing service prefix, so no proto/Caddy change. Add a
language field to EmailRequestRequest and forward it (the backend already seeds it).
Add the NotifyProfile sub-kind + notify.ProfileChanged, published by the confirm-link
handler on a successful link so an in-app session re-fetches its profile when the
email was confirmed in another browser. Regenerated fbs bindings (Go + TS).

pkg/fbs/scrabble.fbs

@@ -132,10 +132,12 @@ table GuestLoginRequest {
 
 // EmailRequestRequest asks the backend to send a login confirm-code to email. It
 // also provisions the account on first contact, so browser_tz (the detected UTC
-// offset) is seeded into its time zone here, not at the later login step.
+// offset) is seeded into its time zone here, not at the later login step; language
+// (the client's UI language) seeds the new account's language and localises the email.
 table EmailRequestRequest {
   email:string;
   browser_tz:string;
+  language:string;
 }
 
 // EmailLoginRequest logs in to the account owning email (provisioned at the
@@ -145,6 +147,21 @@ table EmailLoginRequest {
   code:string;
 }
 
+// EmailConfirmLinkRequest verifies a one-tap deeplink token from a confirmation
+// email. The token, not a session, is the authorization.
+table EmailConfirmLinkRequest {
+  token:string;
+}
+
+// EmailConfirmLinkResult is the outcome of a deeplink confirmation: purpose is
+// "login" or "link"; for a login session carries the minted credential; for a link
+// status is "confirmed" or "merge_required" (the app completes the merge).
+table EmailConfirmLinkResult {
+  purpose:string;
+  status:string;
+  session:Session;
+}
+
 // Session is the minted credential returned by every auth operation.
 table Session {
   token:string;

pkg/fbs/scrabblefb/EmailConfirmLinkRequest.go

@@ -0,0 +1,60 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package scrabblefb
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type EmailConfirmLinkRequest struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsEmailConfirmLinkRequest(buf []byte, offset flatbuffers.UOffsetT) *EmailConfirmLinkRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &EmailConfirmLinkRequest{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishEmailConfirmLinkRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsEmailConfirmLinkRequest(buf []byte, offset flatbuffers.UOffsetT) *EmailConfirmLinkRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &EmailConfirmLinkRequest{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedEmailConfirmLinkRequestBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *EmailConfirmLinkRequest) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *EmailConfirmLinkRequest) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *EmailConfirmLinkRequest) Token() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func EmailConfirmLinkRequestStart(builder *flatbuffers.Builder) {
+	builder.StartObject(1)
+}
+func EmailConfirmLinkRequestAddToken(builder *flatbuffers.Builder, token flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(token), 0)
+}
+func EmailConfirmLinkRequestEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/fbs/scrabblefb/EmailConfirmLinkResult.go

@@ -0,0 +1,87 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package scrabblefb
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type EmailConfirmLinkResult struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsEmailConfirmLinkResult(buf []byte, offset flatbuffers.UOffsetT) *EmailConfirmLinkResult {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &EmailConfirmLinkResult{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishEmailConfirmLinkResultBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsEmailConfirmLinkResult(buf []byte, offset flatbuffers.UOffsetT) *EmailConfirmLinkResult {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &EmailConfirmLinkResult{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedEmailConfirmLinkResultBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *EmailConfirmLinkResult) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *EmailConfirmLinkResult) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *EmailConfirmLinkResult) Purpose() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *EmailConfirmLinkResult) Status() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func (rcv *EmailConfirmLinkResult) Session(obj *Session) *Session {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(8))
+	if o != 0 {
+		x := rcv._tab.Indirect(o + rcv._tab.Pos)
+		if obj == nil {
+			obj = new(Session)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func EmailConfirmLinkResultStart(builder *flatbuffers.Builder) {
+	builder.StartObject(3)
+}
+func EmailConfirmLinkResultAddPurpose(builder *flatbuffers.Builder, purpose flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(purpose), 0)
+}
+func EmailConfirmLinkResultAddStatus(builder *flatbuffers.Builder, status flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(1, flatbuffers.UOffsetT(status), 0)
+}
+func EmailConfirmLinkResultAddSession(builder *flatbuffers.Builder, session flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(2, flatbuffers.UOffsetT(session), 0)
+}
+func EmailConfirmLinkResultEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/fbs/scrabblefb/EmailRequestRequest.go

@@ -57,8 +57,16 @@ func (rcv *EmailRequestRequest) BrowserTz() []byte {
 	return nil
 }
 
+func (rcv *EmailRequestRequest) Language() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(8))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
 func EmailRequestRequestStart(builder *flatbuffers.Builder) {
-	builder.StartObject(2)
+	builder.StartObject(3)
 }
 func EmailRequestRequestAddEmail(builder *flatbuffers.Builder, email flatbuffers.UOffsetT) {
 	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(email), 0)
@@ -66,6 +74,9 @@ func EmailRequestRequestAddEmail(builder *flatbuffers.Builder, email flatbuffers
 func EmailRequestRequestAddBrowserTz(builder *flatbuffers.Builder, browserTz flatbuffers.UOffsetT) {
 	builder.PrependUOffsetTSlot(1, flatbuffers.UOffsetT(browserTz), 0)
 }
+func EmailRequestRequestAddLanguage(builder *flatbuffers.Builder, language flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(2, flatbuffers.UOffsetT(language), 0)
+}
 func EmailRequestRequestEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
 	return builder.EndObject()
 }