Add Discord inbound replies (#15 )

Stacks on #14. Mapped Discord admins can reply in a known thread; those messages become site posts and email the homeowner. The bot does not publish a site event, so the reply is not posted back to Discord. Photo attachments are ignored until the upload pipeline lands on this branch. Reviewed-on: #15 Co-authored-by: codegirl-007 <s.raide@gmail.com>
2026-08-29 18:24:40 +00:00
10 changed files with 97 additions and 381 deletions
@@ -37,7 +37,6 @@ func main() {
 		log.Fatalf("mail: %v", err)
 	}
 	bus := events.New()
-	mail.Subscribe(bus, store.NewPostgres(db), notifier)
 	bot, err := discord.FromEnv(store.NewDiscordLinks(db), bus, store.NewPostgres(db), notifier)
 	if err != nil {
 		log.Fatalf("discord: %v", err)
@@ -45,7 +44,7 @@ func main() {
 	if bot != nil {
 		defer bot.Close()
 	}
-	handler := newHandler(db, sessions, uploader, bus)
+	handler := newHandler(db, sessions, uploader, notifier, bus)
 	run(&http.Server{
 		Addr:              listenAddr(),
 		Handler:           handler,
@@ -69,12 +68,13 @@ func openDB() (*sql.DB, *store.SessionStore) {
 	return db, sessions
 }

-func newHandler(db *sql.DB, sessions *store.SessionStore, uploader blob.Uploader, bus events.Publisher) http.Handler {
+func newHandler(db *sql.DB, sessions *store.SessionStore, uploader blob.Uploader, notifier mail.Notifier, bus events.Publisher) http.Handler {
 	srv, err := web.New(store.NewPostgres(db), sessions.Store(), plumber.TemplateFS, plumber.StaticFS, web.Config{
 		AdminSetupSecret: strings.TrimSpace(os.Getenv("ADMIN_SETUP_SECRET")),
 		SecureCookie:     secureCookieFromEnv(),
 		TrustedProxies:   parseTrustedProxies(os.Getenv("TRUSTED_PROXY_CIDRS")),
 		Blob:             uploader,
+		Mail:             notifier,
 		Events:           bus,
 		BaseURL:          strings.TrimRight(strings.TrimSpace(os.Getenv("APP_BASE_URL")), "/"),
 	})
@@ -9,7 +9,7 @@ import (
 // API is the Discord REST surface used by the outbound subscriber.
 type API interface {
 	SendToChannel(ctx context.Context, channelID string, msg Message) (messageID string, err error)
-	StartThread(ctx context.Context, channelID, name string) (threadID string, err error)
+	StartThread(ctx context.Context, channelID, messageID, name string) (threadID string, err error)
 	SendToThread(ctx context.Context, threadID string, msg Message) (messageID string, err error)
 	Edit(ctx context.Context, channelID, messageID string, msg Message) error
 	Close() error
@@ -27,10 +27,9 @@ func (s *sessionAPI) SendToChannel(_ context.Context, channelID string, msg Mess
 	return sent.ID, nil
 }

-func (s *sessionAPI) StartThread(_ context.Context, channelID, name string) (string, error) {
-	thread, err := s.session.ThreadStartComplex(channelID, &discordgo.ThreadStart{
+func (s *sessionAPI) StartThread(_ context.Context, channelID, messageID, name string) (string, error) {
+	thread, err := s.session.MessageThreadStartComplex(channelID, messageID, &discordgo.ThreadStart{
 		Name:                name,
-		Type:                discordgo.ChannelTypeGuildPublicThread,
 		AutoArchiveDuration: 10080,
 	})
 	if err != nil {
@@ -44,12 +43,10 @@ func (s *sessionAPI) SendToThread(ctx context.Context, threadID string, msg Mess
 }

 func (s *sessionAPI) Edit(_ context.Context, channelID, messageID string, msg Message) error {
-	content := messageContent(msg)
 	embeds := toEmbeds(msg)
 	_, err := s.session.ChannelMessageEditComplex(&discordgo.MessageEdit{
 		ID:      messageID,
 		Channel: channelID,
-		Content: &content,
 		Embeds:  &embeds,
 	})
 	return err
@@ -64,7 +61,6 @@ func (s *sessionAPI) Close() error {

 func toMessageSend(msg Message) *discordgo.MessageSend {
 	return &discordgo.MessageSend{
-		Content:         messageContent(msg),
 		Embeds:          toEmbeds(msg),
 		AllowedMentions: &discordgo.MessageAllowedMentions{},
 	}
@@ -73,7 +69,7 @@ func toMessageSend(msg Message) *discordgo.MessageSend {
 func toEmbeds(msg Message) []*discordgo.MessageEmbed {
 	main := &discordgo.MessageEmbed{
 		Title:       msg.Title,
-		URL:         publicURL(msg.URL),
+		URL:         msg.URL,
 		Description: msg.Description,
 		Color:       embedColor,
 	}
@@ -133,16 +133,16 @@ func (b *Bot) onUpdated(ctx context.Context, ev events.PostEvent) {

 func (b *Bot) createRoot(ctx context.Context, ev events.PostEvent) {
 	msg := formatMessage(ev)
-	threadID, err := b.api.StartThread(ctx, b.channelID, msg.ThreadName)
-	if err != nil {
-		log.Printf("discord: start thread %s: %v", ev.PostID, err)
-		return
-	}
-	messageID, err := b.api.SendToThread(ctx, threadID, msg)
+	messageID, err := b.api.SendToChannel(ctx, b.channelID, msg)
 	if err != nil {
 		log.Printf("discord: send root %s: %v", ev.PostID, err)
 		return
 	}
+	threadID, err := b.api.StartThread(ctx, b.channelID, messageID, msg.ThreadName)
+	if err != nil {
+		log.Printf("discord: start thread %s: %v", ev.PostID, err)
+		return
+	}
 	if err := b.links.Upsert(ctx, store.DiscordLink{
 		PostID:    ev.PostID,
 		MessageID: messageID,
@@ -185,7 +185,7 @@ func (b *Bot) createReply(ctx context.Context, ev events.PostEvent) {

 func (b *Bot) editChannel(ctx context.Context, ev events.PostEvent, link *store.DiscordLink) (string, error) {
 	if strings.TrimSpace(link.ThreadID) != "" {
-		return link.ThreadID, nil
+		return b.channelID, nil
 	}
 	root, err := b.links.GetByPostID(ctx, ev.RootID)
 	if err != nil {
@@ -2,11 +2,11 @@ package discord

 import (
 	"context"
-	"strconv"
-	"strings"
 	"sync"
 	"testing"

+	"strconv"
+
 	"plumber/internal/events"
 	"plumber/internal/store"
 )
@@ -30,18 +30,17 @@ func (f *fakeAPI) SendToChannel(_ context.Context, channelID string, msg Message
 	return f.record("channel", channelID, "", msg)
 }

-func (f *fakeAPI) StartThread(_ context.Context, channelID, name string) (string, error) {
+func (f *fakeAPI) StartThread(_ context.Context, channelID, messageID, name string) (string, error) {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 	f.next++
-	id := "thread-" + strconv.Itoa(f.next)
 	f.sends = append(f.sends, recordedSend{
 		Kind:      "thread",
 		ChannelID: channelID,
 		Name:      name,
-		Msg:       Message{ThreadName: name},
+		Msg:       Message{ThreadName: name, URL: messageID},
 	})
-	return id, nil
+	return "thread-" + messageID, nil
 }

 func (f *fakeAPI) SendToThread(_ context.Context, threadID string, msg Message) (string, error) {
@@ -94,21 +93,17 @@ func TestOutboundRootReplyAndEdit(t *testing.T) {
 	}
 	bot.Handle(ctx, events.PostCreated{PostEvent: root})

-	if len(api.sends) != 2 ||
-		api.sends[0].Kind != "thread" ||
-		api.sends[1].Kind != "thread-msg" {
+	if len(api.sends) != 2 || api.sends[0].Kind != "channel" || api.sends[1].Kind != "thread" {
 		t.Fatalf("root sends = %+v", api.sends)
 	}
-	if api.sends[0].ChannelID != "channel-1" ||
-		api.sends[0].Name != "sam asks: Leaky sink" ||
-		api.sends[1].ChannelID != "thread-1" {
+	if api.sends[0].ChannelID != "channel-1" || api.sends[1].Name != "Leaky sink" {
 		t.Fatalf("root routing = %+v", api.sends)
 	}
-	if got := api.sends[1].Msg.ImageURLs; len(got) != 2 || got[0] != "https://cdn.example/a.jpg" {
+	if got := api.sends[0].Msg.ImageURLs; len(got) != 2 || got[0] != "https://cdn.example/a.jpg" {
 		t.Fatalf("root images = %v", got)
 	}
 	link, err := links.GetByPostID(ctx, "root-1")
-	if err != nil || link.MessageID != "msg-2" || link.ThreadID != "thread-1" {
+	if err != nil || link.MessageID != "msg-1" || link.ThreadID != "thread-msg-1" {
 		t.Fatalf("root link = %+v, %v", link, err)
 	}

@@ -121,7 +116,7 @@ func TestOutboundRootReplyAndEdit(t *testing.T) {
 		Permalink:  "https://www.askaplumberfirst.com/questions/root-1#post-reply-1",
 	}
 	bot.Handle(ctx, events.PostCreated{PostEvent: reply})
-	if len(api.sends) != 3 || api.sends[2].Kind != "thread-msg" || api.sends[2].ChannelID != "thread-1" {
+	if len(api.sends) != 3 || api.sends[2].Kind != "thread-msg" || api.sends[2].ChannelID != "thread-msg-1" {
 		t.Fatalf("reply sends = %+v", api.sends)
 	}
 	replyLink, err := links.GetByPostID(ctx, "reply-1")
@@ -131,7 +126,7 @@ func TestOutboundRootReplyAndEdit(t *testing.T) {

 	root.Body = "Updated leak."
 	bot.Handle(ctx, events.PostUpdated{PostEvent: root})
-	if len(api.edits) != 1 || api.edits[0].ChannelID != "thread-1" || api.edits[0].Name != "msg-2" {
+	if len(api.edits) != 1 || api.edits[0].ChannelID != "channel-1" || api.edits[0].Name != "msg-1" {
 		t.Fatalf("root edit = %+v", api.edits)
 	}
 	if api.edits[0].Msg.Description != "Updated leak." {
@@ -140,7 +135,7 @@ func TestOutboundRootReplyAndEdit(t *testing.T) {

 	reply.Body = "Use a ceramic cartridge."
 	bot.Handle(ctx, events.PostUpdated{PostEvent: reply})
-	if len(api.edits) != 2 || api.edits[1].ChannelID != "thread-1" || api.edits[1].Name != "msg-3" {
+	if len(api.edits) != 2 || api.edits[1].ChannelID != "thread-msg-1" || api.edits[1].Name != "msg-3" {
 		t.Fatalf("reply edit = %+v", api.edits)
 	}
 }
@@ -195,24 +190,15 @@ func TestFormatMessage(t *testing.T) {
 		got.City != "Oakland" ||
 		got.Author != "sam" ||
 		got.URL != "https://example.com/q" ||
-		got.ThreadName != "sam asks: Leaky sink" ||
+		got.ThreadName != "Leaky sink" ||
 		len(got.ImageURLs) != 1 {
 		t.Fatalf("format = %+v", got)
 	}

 	reply := formatMessage(events.PostEvent{Body: "Thanks", AuthorName: ""})
-	if reply.Title != "Reply" || reply.Author != "Someone" || reply.ThreadName != "Someone asks: Question" {
+	if reply.Title != "Reply" || reply.Author != "Someone" || reply.ThreadName != "Question" {
 		t.Fatalf("reply format = %+v", reply)
 	}
-	content := messageContent(got)
-	if strings.Contains(content, "Leaky sink") ||
-		!strings.Contains(content, "It drips.") ||
-		!strings.Contains(content, "Oakland") {
-		t.Fatalf("content = %q", content)
-	}
-	if publicURL("/questions/x") != "" || publicURL("http://localhost:8080/q") != "" {
-		t.Fatal("localhost or relative permalink should not be an embed URL")
-	}
 }

 func TestFromEnvDisabled(t *testing.T) {
@@ -39,7 +39,7 @@ func formatMessage(ev events.PostEvent) Message {
 		Description: truncateRunes(strings.TrimSpace(ev.Body), embedDescriptionLimit),
 		City:        strings.TrimSpace(ev.City),
 		Author:      author,
-		ThreadName:  threadName(author, ev.Title),
+		ThreadName:  threadName(ev.Title),
 	}
 	for _, img := range ev.Images {
 		url := strings.TrimSpace(img.URL)
@@ -51,16 +51,12 @@ func formatMessage(ev events.PostEvent) Message {
 	return msg
 }

-func threadName(author, title string) string {
-	author = strings.TrimSpace(author)
-	if author == "" {
-		author = "Someone"
-	}
+func threadName(title string) string {
 	title = strings.TrimSpace(title)
 	if title == "" {
-		title = "Question"
+		return "Question"
 	}
-	return truncateRunes(author+" asks: "+title, threadNameLimit)
+	return truncateRunes(title, threadNameLimit)
 }

 func truncateRunes(s string, max int) string {
@@ -77,35 +73,3 @@ func truncateRunes(s string, max int) string {
 func isRoot(ev events.PostEvent) bool {
 	return strings.TrimSpace(ev.ParentID) == ""
 }
-
-func messageContent(msg Message) string {
-	var parts []string
-	if body := strings.TrimSpace(msg.Description); body != "" {
-		parts = append(parts, body)
-	}
-	var meta []string
-	if msg.City != "" {
-		meta = append(meta, msg.City)
-	}
-	if msg.Author != "" {
-		meta = append(meta, msg.Author)
-	}
-	if len(meta) > 0 {
-		parts = append(parts, strings.Join(meta, " · "))
-	}
-	if u := publicURL(msg.URL); u != "" {
-		parts = append(parts, u)
-	}
-	return truncateRunes(strings.Join(parts, "\n"), 2000)
-}
-
-func publicURL(raw string) string {
-	raw = strings.TrimSpace(raw)
-	if !strings.HasPrefix(raw, "https://") {
-		return ""
-	}
-	if strings.Contains(raw, "localhost") || strings.Contains(raw, "127.0.0.1") {
-		return ""
-	}
-	return raw
-}
@@ -1,89 +0,0 @@
-package mail
-
-import (
-	"context"
-	"log"
-	"strings"
-	"time"
-
-	"plumber/internal/events"
-	"plumber/internal/store"
-)
-
-// Subscribe sends reply emails from PostCreated events. Nop or nil is a no-op.
-func Subscribe(bus *events.Bus, st store.Store, n Notifier) {
-	if bus == nil || st == nil || n == nil {
-		return
-	}
-	if _, disabled := n.(Nop); disabled {
-		return
-	}
-	s := subscriber{store: st, mail: n}
-	bus.Subscribe(s.handle)
-}
-
-type subscriber struct {
-	store store.Store
-	mail  Notifier
-}
-
-func (s subscriber) handle(_ context.Context, ev any) {
-	created, ok := ev.(events.PostCreated)
-	if !ok {
-		return
-	}
-	if strings.TrimSpace(created.ParentID) == "" {
-		return
-	}
-	go s.notifyReply(created.PostEvent)
-}
-
-func (s subscriber) notifyReply(ev events.PostEvent) {
-	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-	defer cancel()
-
-	parent, err := s.store.GetPost(ctx, ev.ParentID)
-	if err != nil {
-		log.Printf("notify reply %s: load parent: %v", ev.PostID, err)
-		return
-	}
-	root, err := s.store.GetPost(ctx, ev.RootID)
-	if err != nil {
-		log.Printf("notify reply %s: load root: %v", ev.PostID, err)
-		return
-	}
-	author, err := s.store.UserByID(ctx, ev.AuthorID)
-	if err != nil {
-		log.Printf("notify reply %s: load author: %v", ev.PostID, err)
-		return
-	}
-	recipientID := parent.AuthorID
-	if author.Admin() {
-		recipientID = root.AuthorID
-	}
-	if recipientID == author.ID {
-		return
-	}
-	msg := PostReply{
-		RootID:          root.ID,
-		RootTitle:       root.Title,
-		ReplyID:         ev.PostID,
-		ReplyBody:       ev.Body,
-		ReplyAuthorName: author.Name,
-	}
-	recipient, err := s.store.UserByID(ctx, recipientID)
-	if err != nil {
-		log.Printf("notify reply %s: load recipient: %v", msg.ReplyID, err)
-		return
-	}
-	if recipient == nil || strings.TrimSpace(recipient.Email) == "" {
-		return
-	}
-	msg.ToEmail = recipient.Email
-	msg.ToName = recipient.Name
-	if err := s.mail.NotifyPostReply(ctx, msg); err != nil {
-		log.Printf("notify reply %s: %v", msg.ReplyID, err)
-		return
-	}
-	log.Printf("notify reply %s: accepted", msg.ReplyID)
-}
@@ -1,200 +0,0 @@
-package mail
-
-import (
-	"context"
-	"testing"
-	"time"
-
-	"plumber/internal/events"
-	"plumber/internal/pacific"
-	"plumber/internal/store"
-)
-
-func TestSubscribeReplyNotifications(t *testing.T) {
-	t.Parallel()
-
-	mem := store.NewMemory()
-	homeowner := seedMailUser(t, mem, "homeowner", store.RoleUser, "sam@example.com")
-	admin := seedMailUser(t, mem, "plumber", store.RoleAdmin, "pat@example.com")
-	root := seedMailRoot(t, mem, homeowner.ID, "Leaky sink", "It drips.")
-	adminReply := seedMailReply(t, mem, admin.ID, root.ID)
-	homeownerReply := seedMailReply(t, mem, homeowner.ID, adminReply.ID)
-
-	bus := events.New()
-	defer bus.Close()
-	recording := &Recording{}
-	Subscribe(bus, mem, recording)
-
-	ctx := context.Background()
-	bus.Publish(ctx, events.PostCreated{PostEvent: events.PostEvent{
-		PostID:   root.ID,
-		RootID:   root.ID,
-		Title:    root.Title,
-		Body:     root.Body,
-		AuthorID: homeowner.ID,
-	}})
-	bus.Publish(ctx, events.PostUpdated{PostEvent: events.PostEvent{
-		PostID:   adminReply.ID,
-		RootID:   root.ID,
-		ParentID: root.ID,
-		Body:     "Edited",
-		AuthorID: admin.ID,
-	}})
-
-	bus.Publish(ctx, events.PostCreated{PostEvent: events.PostEvent{
-		PostID:   adminReply.ID,
-		RootID:   root.ID,
-		ParentID: root.ID,
-		Body:     adminReply.Body,
-		AuthorID: admin.ID,
-	}})
-	msgs := waitForMail(t, recording, 1)
-	if msg := msgs[0]; msg.ToEmail != homeowner.Email ||
-		msg.RootID != root.ID ||
-		msg.RootTitle != root.Title ||
-		msg.ReplyID != adminReply.ID ||
-		msg.ReplyBody != adminReply.Body ||
-		msg.ReplyAuthorName != admin.Name {
-		t.Fatalf("admin reply = %+v", msg)
-	}
-
-	bus.Publish(ctx, events.PostCreated{PostEvent: events.PostEvent{
-		PostID:   homeownerReply.ID,
-		RootID:   root.ID,
-		ParentID: adminReply.ID,
-		Body:     homeownerReply.Body,
-		AuthorID: homeowner.ID,
-	}})
-	msgs = waitForMail(t, recording, 2)
-	if msg := msgs[1]; msg.ToEmail != admin.Email ||
-		msg.RootID != root.ID ||
-		msg.ReplyID != homeownerReply.ID ||
-		msg.ReplyAuthorName != homeowner.Name {
-		t.Fatalf("homeowner reply = %+v", msg)
-	}
-
-	nestedAdmin := seedMailReply(t, mem, admin.ID, adminReply.ID)
-	bus.Publish(ctx, events.PostCreated{PostEvent: events.PostEvent{
-		PostID:   nestedAdmin.ID,
-		RootID:   root.ID,
-		ParentID: adminReply.ID,
-		Body:     nestedAdmin.Body,
-		AuthorID: admin.ID,
-	}})
-	msgs = waitForMail(t, recording, 3)
-	if msg := msgs[2]; msg.ToEmail != homeowner.Email ||
-		msg.RootID != root.ID ||
-		msg.ReplyBody != nestedAdmin.Body ||
-		msg.ReplyAuthorName != admin.Name {
-		t.Fatalf("nested admin reply = %+v", msg)
-	}
-
-	self := seedMailReply(t, mem, homeowner.ID, root.ID)
-	bus.Publish(ctx, events.PostCreated{PostEvent: events.PostEvent{
-		PostID:   self.ID,
-		RootID:   root.ID,
-		ParentID: root.ID,
-		Body:     self.Body,
-		AuthorID: homeowner.ID,
-	}})
-
-	noEmail := seedMailUser(t, mem, "quiet", store.RoleUser, "")
-	quietRoot := seedMailRoot(t, mem, noEmail.ID, "Quiet thread", "No email.")
-	quietReply := seedMailReply(t, mem, admin.ID, quietRoot.ID)
-	bus.Publish(ctx, events.PostCreated{PostEvent: events.PostEvent{
-		PostID:   quietReply.ID,
-		RootID:   quietRoot.ID,
-		ParentID: quietRoot.ID,
-		Body:     quietReply.Body,
-		AuthorID: admin.ID,
-	}})
-
-	time.Sleep(50 * time.Millisecond)
-	if recording.Len() != 3 {
-		t.Fatalf("self, root, edit, or no-email sent mail: %+v", recording.Snapshot())
-	}
-}
-
-func TestSubscribeNopIgnoresReplies(t *testing.T) {
-	t.Parallel()
-
-	mem := store.NewMemory()
-	homeowner := seedMailUser(t, mem, "homeowner", store.RoleUser, "sam@example.com")
-	admin := seedMailUser(t, mem, "plumber", store.RoleAdmin, "pat@example.com")
-	root := seedMailRoot(t, mem, homeowner.ID, "Leaky sink", "It drips.")
-	reply := seedMailReply(t, mem, admin.ID, root.ID)
-
-	bus := events.New()
-	defer bus.Close()
-	recording := &Recording{}
-	Subscribe(bus, mem, Nop{})
-	Subscribe(nil, mem, recording)
-	Subscribe(bus, mem, nil)
-
-	bus.Publish(context.Background(), events.PostCreated{PostEvent: events.PostEvent{
-		PostID:   reply.ID,
-		RootID:   root.ID,
-		ParentID: root.ID,
-		Body:     reply.Body,
-		AuthorID: admin.ID,
-	}})
-	time.Sleep(50 * time.Millisecond)
-	if recording.Len() != 0 {
-		t.Fatalf("Nop or nil subscribe sent mail: %+v", recording.Snapshot())
-	}
-}
-
-func seedMailUser(t *testing.T, mem *store.Memory, username string, role store.Role, email string) *store.User {
-	t.Helper()
-	u := &store.User{
-		Username:     username,
-		Name:         username,
-		Email:        email,
-		PasswordHash: "x",
-		Role:         role,
-	}
-	if err := mem.CreateUser(context.Background(), u); err != nil {
-		t.Fatal(err)
-	}
-	return u
-}
-
-func seedMailRoot(t *testing.T, mem *store.Memory, authorID, title, body string) *store.Post {
-	t.Helper()
-	root := &store.Post{
-		AuthorID: authorID,
-		Title:    title,
-		Body:     body,
-		PostDate: pacific.Today(),
-	}
-	if err := mem.CreatePost(context.Background(), root); err != nil {
-		t.Fatal(err)
-	}
-	return root
-}
-
-func seedMailReply(t *testing.T, mem *store.Memory, authorID, parentID string) *store.Post {
-	t.Helper()
-	reply := &store.Post{
-		ParentID: &parentID,
-		AuthorID: authorID,
-		Body:     "Reply from " + authorID,
-	}
-	if err := mem.CreatePost(context.Background(), reply); err != nil {
-		t.Fatal(err)
-	}
-	return reply
-}
-
-func waitForMail(t *testing.T, recording *Recording, want int) []PostReply {
-	t.Helper()
-	deadline := time.Now().Add(2 * time.Second)
-	for time.Now().Before(deadline) {
-		if recording.Len() >= want {
-			return recording.Snapshot()
-		}
-		time.Sleep(10 * time.Millisecond)
-	}
-	t.Fatalf("recorded %d notifications, want %d", recording.Len(), want)
-	return nil
-}
@@ -5,12 +5,15 @@ import (
 	"database/sql"
 	"errors"
 	"fmt"
+	"log"
 	"net/http"
 	"net/url"
 	"strings"
+	"time"

 	"github.com/go-chi/chi/v5"

+	"plumber/internal/mail"
 	"plumber/internal/store"
 )

@@ -79,6 +82,9 @@ func (s *Server) handleCreatePost(w http.ResponseWriter, r *http.Request) {
 	if root == nil {
 		root = post
 	}
+	if parent != nil {
+		s.notifyPostReply(parent, root, post, user)
+	}
 	s.publishPostCreated(post, root, user)
 	http.Redirect(
 		w,
@@ -88,6 +94,59 @@ func (s *Server) handleCreatePost(w http.ResponseWriter, r *http.Request) {
 	)
 }

+// notifyPostReply emails the root homeowner for admin replies and the direct
+// parent author for homeowner replies.
+func (s *Server) notifyPostReply(
+	parent *store.Post,
+	root *store.Post,
+	reply *store.Post,
+	replyAuthor *store.User,
+) {
+	if parent == nil ||
+		root == nil ||
+		reply == nil ||
+		replyAuthor == nil ||
+		s.cfg.Mail == nil {
+		return
+	}
+	if _, disabled := s.cfg.Mail.(mail.Nop); disabled {
+		return
+	}
+	recipientID := parent.AuthorID
+	if replyAuthor.Admin() {
+		recipientID = root.AuthorID
+	}
+	if recipientID == replyAuthor.ID {
+		return
+	}
+	msg := mail.PostReply{
+		RootID:          root.ID,
+		RootTitle:       root.Title,
+		ReplyID:         reply.ID,
+		ReplyBody:       reply.Body,
+		ReplyAuthorName: replyAuthor.Name,
+	}
+	go func() {
+		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+		recipient, err := s.store.UserByID(ctx, recipientID)
+		if err != nil {
+			log.Printf("notify reply %s: load recipient: %v", msg.ReplyID, err)
+			return
+		}
+		if recipient == nil || strings.TrimSpace(recipient.Email) == "" {
+			return
+		}
+		msg.ToEmail = recipient.Email
+		msg.ToName = recipient.Name
+		if err := s.cfg.Mail.NotifyPostReply(ctx, msg); err != nil {
+			log.Printf("notify reply %s: %v", msg.ReplyID, err)
+			return
+		}
+		log.Printf("notify reply %s: accepted", msg.ReplyID)
+	}()
+}
+
 // handleEditPost updates only a post's body after verifying that the current
 // homeowner owns it or that an admin is editing an admin-authored post.
 func (s *Server) handleEditPost(w http.ResponseWriter, r *http.Request) {
@@ -9,7 +9,6 @@ import (
 	"testing"
 	"time"

-	"plumber/internal/events"
 	"plumber/internal/mail"
 	"plumber/internal/pacific"
 	"plumber/internal/store"
@@ -264,12 +263,8 @@ func TestEditPostRoutePermissions(t *testing.T) {
 func TestPostReplyNotifications(t *testing.T) {
 	t.Parallel()

-	mem := store.NewMemory()
-	bus := events.New()
-	defer bus.Close()
 	recording := &mail.Recording{}
-	mail.Subscribe(bus, mem, recording)
-	srv := newTestServerStore(t, mem, Config{Events: bus})
+	srv, mem := newTestServer(t, Config{Mail: recording})
 	handler := srv.Handler()
 	homeowner := seedUser(t, mem, uniq("homeowner"), "hunter22", store.RoleUser)
 	admin := seedUser(t, mem, uniq("admin"), "hunter22", store.RoleAdmin)
@@ -22,6 +22,7 @@ import (
 	"plumber/internal/blob"
 	"plumber/internal/events"
 	"plumber/internal/geo"
+	"plumber/internal/mail"
 	"plumber/internal/pacific"
 	"plumber/internal/store"
 )
@@ -34,6 +35,7 @@ type Config struct {
 	// TrustedProxies are CIDRs allowed to set X-Forwarded-For (direct peer).
 	TrustedProxies []*net.IPNet
 	Blob           blob.Uploader
+	Mail           mail.Notifier
 	Events         events.Publisher
 	BaseURL        string
 }
@@ -108,6 +110,9 @@ func New(st store.Store, sessionStore scs.Store, templateFS fs.FS, staticFS fs.F
 	if cfg.Blob == nil {
 		cfg.Blob = blob.Disabled{}
 	}
+	if cfg.Mail == nil {
+		cfg.Mail = mail.Nop{}
+	}
 	if cfg.Events == nil {
 		cfg.Events = events.Nop{}
 	}