Notify question authors via Resend when an admin posts the first answer.

Require email at registration (editable on profile), add a Resend mailer with idempotent first-answer sends, and keep answer saves independent of delivery.

.env.example

@@ -14,6 +14,11 @@ SECURE_COOKIE=0
 # Comma-separated CIDRs of reverse proxies allowed to set X-Forwarded-For
 # (direct peer must match). Leave unset to ignore XFF and use RemoteAddr.
 # TRUSTED_PROXY_CIDRS=10.0.0.0/8,192.168.0.0/16
+# Resend (answer notifications). Leave RESEND_API_KEY unset to disable.
+# RESEND_API_KEY=re_xxxxxxxxx
+# RESEND_FROM=Ask a Plumber <notify@yourdomain.com>
+# Public site origin used in email links (required when Resend is enabled):
+# APP_BASE_URL=https://askaplumber.example
 # DigitalOcean Spaces (profile avatars). Leave unset to disable uploads.
 # SPACES_KEY=
 # SPACES_SECRET=

cmd/server/main.go

@@ -17,6 +17,7 @@ import (
 
 	"plumber"
 	"plumber/internal/blob"
+	"plumber/internal/mail"
 	"plumber/internal/store"
 	"plumber/internal/web"
 )
@@ -29,7 +30,11 @@ func main() {
 	defer sessions.Close()
 
 	uploader := blob.FromEnv()
-	handler := newHandler(db, sessions, uploader)
+	notifier, err := mail.FromEnv()
+	if err != nil {
+		log.Fatalf("mail: %v", err)
+	}
+	handler := newHandler(db, sessions, uploader, notifier)
 	run(&http.Server{
 		Addr:              listenAddr(),
 		Handler:           handler,
@@ -53,12 +58,13 @@ func openDB() (*sql.DB, *store.SessionStore) {
 	return db, sessions
 }
 
-func newHandler(db *sql.DB, sessions *store.SessionStore, uploader blob.Uploader) http.Handler {
+func newHandler(db *sql.DB, sessions *store.SessionStore, uploader blob.Uploader, notifier mail.Notifier) 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,
 	})
 	if err != nil {
 		log.Fatalf("server: %v", err)

db/queries/users.sql

@@ -1,24 +1,25 @@
 -- name: CreateUser :exec
-INSERT INTO users (id, username, name, password_hash, role, avatar_url, state, created_at)
-VALUES ($1, $2, $3, $4, $5, '', '', $6);
+INSERT INTO users (id, username, name, password_hash, role, email, avatar_url, state, created_at)
+VALUES ($1, $2, $3, $4, $5, $6, '', '', $7);
 
 -- name: GetUserByID :one
-SELECT id, username, name, role, avatar_url, state, created_at
+SELECT id, username, name, role, email, avatar_url, state, created_at
 FROM users
 WHERE id = $1;
 
 -- name: GetUserByUsername :one
-SELECT id, username, name, role, avatar_url, state, created_at, password_hash
+SELECT id, username, name, role, email, avatar_url, state, created_at, password_hash
 FROM users
 WHERE username = $1;
 
 -- name: ListUsers :many
-SELECT id, username, name, role, avatar_url, state, created_at
+SELECT id, username, name, role, email, avatar_url, state, created_at
 FROM users
 WHERE (
   sqlc.arg(search) = ''
   OR username ILIKE '%' || sqlc.arg(search) || '%'
   OR name ILIKE '%' || sqlc.arg(search) || '%'
+  OR email ILIKE '%' || sqlc.arg(search) || '%'
 )
 AND (
   sqlc.arg(cursor_created) = ''
@@ -43,12 +44,12 @@ UPDATE users
 SET role = $1
 WHERE id = $2;
 
--- name: UpdateUserState :exec
+-- name: UpdateUserProfile :exec
 UPDATE users
-SET state = $1
-WHERE id = $2;
-
--- name: UpdateUserStateAndAvatar :exec
-UPDATE users
-SET state = $1, avatar_url = $2
+SET state = $1, email = $2
 WHERE id = $3;
+
+-- name: UpdateUserProfileAndAvatar :exec
+UPDATE users
+SET state = $1, email = $2, avatar_url = $3
+WHERE id = $4;

go.mod

@@ -28,6 +28,7 @@ require (
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
 	github.com/jackc/puddle/v2 v2.2.2 // indirect
+	github.com/resend/resend-go/v3 v3.16.0 // indirect
 	golang.org/x/sync v0.22.0 // indirect
 	golang.org/x/text v0.41.0 // indirect
 )

go.sum

@@ -43,6 +43,8 @@ github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
 github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/resend/resend-go/v3 v3.16.0 h1:t0Z/7k2sxnJGw8SjsCM9O8qkq3YRRHzTxWQNjhF2KhE=
+github.com/resend/resend-go/v3 v3.16.0/go.mod h1:iI7VA0NoGjWvsNii5iNC5Dy0llsI3HncXPejhniYzwE=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=

internal/mail/mail.go

@@ -0,0 +1,108 @@
+package mail
+
+import (
+	"context"
+	"fmt"
+	"html"
+	"os"
+	"strings"
+
+	"github.com/resend/resend-go/v3"
+)
+
+// QuestionAnswered is the payload for notifying a question author of a reply.
+type QuestionAnswered struct {
+	ToEmail       string
+	ToName        string
+	QuestionID    string
+	QuestionTitle string
+	AnswerBody    string
+}
+
+// Notifier sends transactional email about answered questions.
+type Notifier interface {
+	NotifyQuestionAnswered(ctx context.Context, msg QuestionAnswered) error
+}
+
+// Nop is a no-op Notifier used when Resend is not configured.
+type Nop struct{}
+
+func (Nop) NotifyQuestionAnswered(context.Context, QuestionAnswered) error { return nil }
+
+// Resend sends via the Resend HTTP API.
+type Resend struct {
+	client  *resend.Client
+	from    string
+	baseURL string
+}
+
+// FromEnv builds a Notifier from RESEND_* and APP_BASE_URL.
+// Returns Nop when RESEND_API_KEY is unset.
+func FromEnv() (Notifier, error) {
+	key := strings.TrimSpace(os.Getenv("RESEND_API_KEY"))
+	if key == "" {
+		return Nop{}, nil
+	}
+	from := strings.TrimSpace(os.Getenv("RESEND_FROM"))
+	base := strings.TrimRight(strings.TrimSpace(os.Getenv("APP_BASE_URL")), "/")
+	if from == "" {
+		return nil, fmt.Errorf("RESEND_FROM is required when RESEND_API_KEY is set")
+	}
+	if base == "" {
+		return nil, fmt.Errorf("APP_BASE_URL is required when RESEND_API_KEY is set")
+	}
+	return &Resend{
+		client:  resend.NewClient(key),
+		from:    from,
+		baseURL: base,
+	}, nil
+}
+
+func (r *Resend) NotifyQuestionAnswered(ctx context.Context, msg QuestionAnswered) error {
+	if r == nil || r.client == nil {
+		return nil
+	}
+	to := strings.TrimSpace(msg.ToEmail)
+	if to == "" {
+		return nil
+	}
+	link := r.baseURL + "/questions/" + msg.QuestionID
+	title := strings.TrimSpace(msg.QuestionTitle)
+	if title == "" {
+		title = "your question"
+	}
+	text := fmt.Sprintf(
+		"Hi%s,\n\nYour question %q has an answer from a plumber:\n\n%s\n\nView it here:\n%s\n",
+		greetingName(msg.ToName),
+		title,
+		msg.AnswerBody,
+		link,
+	)
+	htmlBody := fmt.Sprintf(
+		`<p>Hi%s,</p><p>Your question <strong>%s</strong> has an answer from a plumber:</p><blockquote style="margin:1em 0;padding:0.75em 1em;border-left:3px solid #ccc;white-space:pre-wrap">%s</blockquote><p><a href="%s">View the answer</a></p>`,
+		html.EscapeString(greetingName(msg.ToName)),
+		html.EscapeString(title),
+		html.EscapeString(msg.AnswerBody),
+		html.EscapeString(link),
+	)
+	params := &resend.SendEmailRequest{
+		From:    r.from,
+		To:      []string{to},
+		Subject: "Your question was answered",
+		Text:    text,
+		Html:    htmlBody,
+	}
+	opts := &resend.SendEmailOptions{
+		IdempotencyKey: "answer-notify:" + msg.QuestionID,
+	}
+	_, err := r.client.Emails.SendWithOptions(ctx, params, opts)
+	return err
+}
+
+func greetingName(name string) string {
+	name = strings.TrimSpace(name)
+	if name == "" {
+		return ""
+	}
+	return " " + name
+}

internal/mail/recording.go

@@ -0,0 +1,34 @@
+package mail
+
+import (
+	"context"
+	"sync"
+)
+
+// Recording is a test Notifier that records calls.
+type Recording struct {
+	mu   sync.Mutex
+	Msgs []QuestionAnswered
+}
+
+func (r *Recording) NotifyQuestionAnswered(_ context.Context, msg QuestionAnswered) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	r.Msgs = append(r.Msgs, msg)
+	return nil
+}
+
+func (r *Recording) Len() int {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	return len(r.Msgs)
+}
+
+// Snapshot returns a copy of recorded messages.
+func (r *Recording) Snapshot() []QuestionAnswered {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	out := make([]QuestionAnswered, len(r.Msgs))
+	copy(out, r.Msgs)
+	return out
+}

internal/store/email.go

@@ -0,0 +1,52 @@
+package store
+
+import (
+	"fmt"
+	"net/mail"
+	"strings"
+	"unicode/utf8"
+)
+
+const (
+	minEmailLen = 3
+	maxEmailLen = 254
+)
+
+// NormalizeEmail trims and lowercases an address for storage/comparison.
+func NormalizeEmail(s string) string {
+	return strings.ToLower(strings.TrimSpace(s))
+}
+
+// ValidateEmail returns a normalized address or an error message suitable for UI.
+func ValidateEmail(raw string) (normalized string, errMsg string) {
+	normalized = NormalizeEmail(raw)
+	if normalized == "" {
+		return "", "Email is required."
+	}
+	n := utf8.RuneCountInString(normalized)
+	if n < minEmailLen || len(normalized) > maxEmailLen {
+		return "", "Enter a valid email address."
+	}
+	addr, err := mail.ParseAddress(normalized)
+	if err != nil || addr.Address != normalized {
+		return "", "Enter a valid email address."
+	}
+	at := strings.LastIndex(normalized, "@")
+	if at < 1 || at == len(normalized)-1 {
+		return "", "Enter a valid email address."
+	}
+	domain := normalized[at+1:]
+	if !strings.Contains(domain, ".") || strings.HasPrefix(domain, ".") || strings.HasSuffix(domain, ".") {
+		return "", "Enter a valid email address."
+	}
+	return normalized, ""
+}
+
+// MustValidateEmail is like ValidateEmail but returns a Go error.
+func MustValidateEmail(raw string) (string, error) {
+	n, msg := ValidateEmail(raw)
+	if msg != "" {
+		return "", fmt.Errorf("%s", msg)
+	}
+	return n, nil
+}

internal/store/email_test.go

@@ -0,0 +1,21 @@
+package store
+
+import "testing"
+
+func TestValidateEmail(t *testing.T) {
+	cases := []struct {
+		in, want, err string
+	}{
+		{"", "", "Email is required."},
+		{"  Alice@Example.COM ", "alice@example.com", ""},
+		{"not-an-email", "", "Enter a valid email address."},
+		{"a@b", "", "Enter a valid email address."},
+		{"ok@example.com", "ok@example.com", ""},
+	}
+	for _, tc := range cases {
+		got, msg := ValidateEmail(tc.in)
+		if got != tc.want || msg != tc.err {
+			t.Fatalf("%q: got (%q, %q) want (%q, %q)", tc.in, got, msg, tc.want, tc.err)
+		}
+	}
+}

internal/store/memory.go

@@ -42,9 +42,17 @@ func (m *Memory) CreateUser(_ context.Context, u *User) error {
 		return fmt.Errorf("invalid role")
 	}
 	u.Username = NormalizeUsername(u.Username)
+	u.Email = NormalizeEmail(u.Email)
 	if _, ok := m.byName[u.Username]; ok {
 		return ErrDuplicateUsername
 	}
+	if u.Email != "" {
+		for _, existing := range m.users {
+			if existing.Email == u.Email {
+				return ErrDuplicateEmail
+			}
+		}
+	}
 	if u.ID == "" {
 		u.ID = uuid.NewString()
 	}
@@ -179,11 +187,21 @@ func (m *Memory) SaveUserProfile(_ context.Context, u *User) error {
 	if !ok {
 		return sql.ErrNoRows
 	}
+	email := NormalizeEmail(u.Email)
+	if email != "" {
+		for id, existing := range m.users {
+			if id != u.ID && existing.Email == email {
+				return ErrDuplicateEmail
+			}
+		}
+	}
 	cur.State = strings.TrimSpace(u.State)
+	cur.Email = email
 	if u.AvatarURL != "" {
 		cur.AvatarURL = u.AvatarURL
 	}
 	u.State = cur.State
+	u.Email = cur.Email
 	u.AvatarURL = cur.AvatarURL
 	return nil
 }

internal/store/migrate.go

@@ -21,6 +21,20 @@ func migrateUserProfileColumns(ctx context.Context, exec execContext) error {
 	return nil
 }
 
+// migrateUserEmail adds email and a partial unique index on lower(email).
+func migrateUserEmail(ctx context.Context, exec execContext) error {
+	if _, err := exec.ExecContext(ctx, `ALTER TABLE users ADD COLUMN IF NOT EXISTS email TEXT NOT NULL DEFAULT ''`); err != nil {
+		return fmt.Errorf("add column email: %w", err)
+	}
+	if _, err := exec.ExecContext(ctx, `
+CREATE UNIQUE INDEX IF NOT EXISTS users_email_lower_uidx
+  ON users (lower(email))
+  WHERE email <> ''`); err != nil {
+		return fmt.Errorf("users_email_lower_uidx: %w", err)
+	}
+	return nil
+}
+
 type execContext interface {
 	ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error)
 	QueryContext(ctx context.Context, query string, args ...any) (*sql.Rows, error)
@@ -66,6 +80,7 @@ CREATE TABLE IF NOT EXISTS schema_migrations (
 			return applySchema(ctx, exec, schemaSQL)
 		}},
 		{"002_user_profile_columns", migrateUserProfileColumns},
+		{"003_user_email", migrateUserEmail},
 	}
 	for _, m := range migrations {
 		if applied[m.version] {

internal/store/postgres_store.go

@@ -29,6 +29,7 @@ func (p *Postgres) CreateUser(ctx context.Context, u *User) error {
 		return fmt.Errorf("invalid role")
 	}
 	u.Username = NormalizeUsername(u.Username)
+	u.Email = NormalizeEmail(u.Email)
 	if u.ID == "" {
 		u.ID = uuid.NewString()
 	}
@@ -69,6 +70,7 @@ func (p *Postgres) CreateUser(ctx context.Context, u *User) error {
 		Name:         u.Name,
 		PasswordHash: u.PasswordHash,
 		Role:         string(role),
+		Email:        u.Email,
 		CreatedAt:    u.CreatedAt,
 	}); err != nil {
 		return mapUniqueViolation(err)

internal/store/sqlc/models.go

@@ -39,6 +39,7 @@ type User struct {
 	Name         string
 	PasswordHash string
 	Role         string
+	Email        string
 	AvatarUrl    string
 	State        string
 	CreatedAt    string

internal/store/sqlc/users.sql.go

@@ -24,8 +24,8 @@ func (q *Queries) CountAdmins(ctx context.Context, role string) (int64, error) {
 }
 
 const createUser = `-- name: CreateUser :exec
-INSERT INTO users (id, username, name, password_hash, role, avatar_url, state, created_at)
-VALUES ($1, $2, $3, $4, $5, '', '', $6)
+INSERT INTO users (id, username, name, password_hash, role, email, avatar_url, state, created_at)
+VALUES ($1, $2, $3, $4, $5, $6, '', '', $7)
 `
 
 type CreateUserParams struct {
@@ -34,6 +34,7 @@ type CreateUserParams struct {
 	Name         string
 	PasswordHash string
 	Role         string
+	Email        string
 	CreatedAt    string
 }
 
@@ -44,13 +45,14 @@ func (q *Queries) CreateUser(ctx context.Context, arg CreateUserParams) error {
 		arg.Name,
 		arg.PasswordHash,
 		arg.Role,
+		arg.Email,
 		arg.CreatedAt,
 	)
 	return err
 }
 
 const getUserByID = `-- name: GetUserByID :one
-SELECT id, username, name, role, avatar_url, state, created_at
+SELECT id, username, name, role, email, avatar_url, state, created_at
 FROM users
 WHERE id = $1
 `
@@ -60,6 +62,7 @@ type GetUserByIDRow struct {
 	Username  string
 	Name      string
 	Role      string
+	Email     string
 	AvatarUrl string
 	State     string
 	CreatedAt string
@@ -73,6 +76,7 @@ func (q *Queries) GetUserByID(ctx context.Context, id string) (GetUserByIDRow, e
 		&i.Username,
 		&i.Name,
 		&i.Role,
+		&i.Email,
 		&i.AvatarUrl,
 		&i.State,
 		&i.CreatedAt,
@@ -81,7 +85,7 @@ func (q *Queries) GetUserByID(ctx context.Context, id string) (GetUserByIDRow, e
 }
 
 const getUserByUsername = `-- name: GetUserByUsername :one
-SELECT id, username, name, role, avatar_url, state, created_at, password_hash
+SELECT id, username, name, role, email, avatar_url, state, created_at, password_hash
 FROM users
 WHERE username = $1
 `
@@ -91,6 +95,7 @@ type GetUserByUsernameRow struct {
 	Username     string
 	Name         string
 	Role         string
+	Email        string
 	AvatarUrl    string
 	State        string
 	CreatedAt    string
@@ -105,6 +110,7 @@ func (q *Queries) GetUserByUsername(ctx context.Context, username string) (GetUs
 		&i.Username,
 		&i.Name,
 		&i.Role,
+		&i.Email,
 		&i.AvatarUrl,
 		&i.State,
 		&i.CreatedAt,
@@ -127,12 +133,13 @@ func (q *Queries) GetUserRole(ctx context.Context, id string) (string, error) {
 }
 
 const listUsers = `-- name: ListUsers :many
-SELECT id, username, name, role, avatar_url, state, created_at
+SELECT id, username, name, role, email, avatar_url, state, created_at
 FROM users
 WHERE (
   $1 = ''
   OR username ILIKE '%' || $1 || '%'
   OR name ILIKE '%' || $1 || '%'
+  OR email ILIKE '%' || $1 || '%'
 )
 AND (
   $2 = ''
@@ -155,6 +162,7 @@ type ListUsersRow struct {
 	Username  string
 	Name      string
 	Role      string
+	Email     string
 	AvatarUrl string
 	State     string
 	CreatedAt string
@@ -179,6 +187,7 @@ func (q *Queries) ListUsers(ctx context.Context, arg ListUsersParams) ([]ListUse
 			&i.Username,
 			&i.Name,
 			&i.Role,
+			&i.Email,
 			&i.AvatarUrl,
 			&i.State,
 			&i.CreatedAt,
@@ -196,6 +205,46 @@ func (q *Queries) ListUsers(ctx context.Context, arg ListUsersParams) ([]ListUse
 	return items, nil
 }
 
+const updateUserProfile = `-- name: UpdateUserProfile :exec
+UPDATE users
+SET state = $1, email = $2
+WHERE id = $3
+`
+
+type UpdateUserProfileParams struct {
+	State string
+	Email string
+	ID    string
+}
+
+func (q *Queries) UpdateUserProfile(ctx context.Context, arg UpdateUserProfileParams) error {
+	_, err := q.db.ExecContext(ctx, updateUserProfile, arg.State, arg.Email, arg.ID)
+	return err
+}
+
+const updateUserProfileAndAvatar = `-- name: UpdateUserProfileAndAvatar :exec
+UPDATE users
+SET state = $1, email = $2, avatar_url = $3
+WHERE id = $4
+`
+
+type UpdateUserProfileAndAvatarParams struct {
+	State     string
+	Email     string
+	AvatarUrl string
+	ID        string
+}
+
+func (q *Queries) UpdateUserProfileAndAvatar(ctx context.Context, arg UpdateUserProfileAndAvatarParams) error {
+	_, err := q.db.ExecContext(ctx, updateUserProfileAndAvatar,
+		arg.State,
+		arg.Email,
+		arg.AvatarUrl,
+		arg.ID,
+	)
+	return err
+}
+
 const updateUserRole = `-- name: UpdateUserRole :execresult
 UPDATE users
 SET role = $1
@@ -210,36 +259,3 @@ type UpdateUserRoleParams struct {
 func (q *Queries) UpdateUserRole(ctx context.Context, arg UpdateUserRoleParams) (sql.Result, error) {
 	return q.db.ExecContext(ctx, updateUserRole, arg.Role, arg.ID)
 }
-
-const updateUserState = `-- name: UpdateUserState :exec
-UPDATE users
-SET state = $1
-WHERE id = $2
-`
-
-type UpdateUserStateParams struct {
-	State string
-	ID    string
-}
-
-func (q *Queries) UpdateUserState(ctx context.Context, arg UpdateUserStateParams) error {
-	_, err := q.db.ExecContext(ctx, updateUserState, arg.State, arg.ID)
-	return err
-}
-
-const updateUserStateAndAvatar = `-- name: UpdateUserStateAndAvatar :exec
-UPDATE users
-SET state = $1, avatar_url = $2
-WHERE id = $3
-`
-
-type UpdateUserStateAndAvatarParams struct {
-	State     string
-	AvatarUrl string
-	ID        string
-}
-
-func (q *Queries) UpdateUserStateAndAvatar(ctx context.Context, arg UpdateUserStateAndAvatarParams) error {
-	_, err := q.db.ExecContext(ctx, updateUserStateAndAvatar, arg.State, arg.AvatarUrl, arg.ID)
-	return err
-}

internal/store/user.go

@@ -30,6 +30,7 @@ type User struct {
 	Username     string
 	Name         string
 	Role         Role
+	Email        string
 	AvatarURL    string
 	State        string
 	CreatedAt    string
@@ -50,12 +51,13 @@ func NormalizeUsername(s string) string {
 	return strings.ToLower(strings.TrimSpace(s))
 }
 
-func toUser(db *sql.DB, id, username, name, role, avatarURL, state, createdAt, passwordHash string) *User {
+func toUser(db *sql.DB, id, username, name, role, email, avatarURL, state, createdAt, passwordHash string) *User {
 	return &User{
 		ID:           id,
 		Username:     username,
 		Name:         name,
 		Role:         Role(role),
+		Email:        email,
 		AvatarURL:    avatarURL,
 		State:        state,
 		CreatedAt:    createdAt,
@@ -73,6 +75,7 @@ func (u *User) Create(ctx context.Context) error {
 		return fmt.Errorf("invalid role")
 	}
 	u.Username = NormalizeUsername(u.Username)
+	u.Email = NormalizeEmail(u.Email)
 	if u.ID == "" {
 		u.ID = uuid.NewString()
 	}
@@ -88,6 +91,7 @@ func (u *User) Create(ctx context.Context) error {
 		Name:         u.Name,
 		PasswordHash: u.PasswordHash,
 		Role:         string(u.Role),
+		Email:        u.Email,
 		CreatedAt:    u.CreatedAt,
 	}))
 }
@@ -149,21 +153,27 @@ func (u *User) SetRole(ctx context.Context, role Role) error {
 	return nil
 }
 
-// SaveProfile writes State and optionally AvatarURL.
+// SaveProfile writes Email, State, and optionally AvatarURL.
 func (u *User) SaveProfile(ctx context.Context) error {
 	if u == nil || u.db == nil {
 		return fmt.Errorf("user: no database")
 	}
 	u.State = strings.TrimSpace(u.State)
+	u.Email = NormalizeEmail(u.Email)
 	q := sqlc.New(u.db)
 	if u.AvatarURL == "" {
-		return q.UpdateUserState(ctx, sqlc.UpdateUserStateParams{State: u.State, ID: u.ID})
-	}
-	return q.UpdateUserStateAndAvatar(ctx, sqlc.UpdateUserStateAndAvatarParams{
+		return mapUniqueViolation(q.UpdateUserProfile(ctx, sqlc.UpdateUserProfileParams{
 			State: u.State,
+			Email: u.Email,
+			ID:    u.ID,
+		}))
+	}
+	return mapUniqueViolation(q.UpdateUserProfileAndAvatar(ctx, sqlc.UpdateUserProfileAndAvatarParams{
+		State:     u.State,
+		Email:     u.Email,
 		AvatarUrl: u.AvatarURL,
 		ID:        u.ID,
-	})
+	}))
 }
 
 func CountAdmins(ctx context.Context, db *sql.DB) (int, error) {
@@ -187,7 +197,7 @@ func ListUsers(ctx context.Context, db *sql.DB, q ListUsersQuery) ([]User, strin
 	}
 	out := make([]User, 0, len(rows))
 	for _, r := range rows {
-		u := toUser(db, r.ID, r.Username, r.Name, r.Role, r.AvatarUrl, r.State, r.CreatedAt, "")
+		u := toUser(db, r.ID, r.Username, r.Name, r.Role, r.Email, r.AvatarUrl, r.State, r.CreatedAt, "")
 		out = append(out, *u)
 	}
 	var nextCreated, nextID string
@@ -204,7 +214,7 @@ func UserByID(ctx context.Context, db *sql.DB, id string) (*User, error) {
 	if err != nil {
 		return nil, err
 	}
-	return toUser(db, r.ID, r.Username, r.Name, r.Role, r.AvatarUrl, r.State, r.CreatedAt, ""), nil
+	return toUser(db, r.ID, r.Username, r.Name, r.Role, r.Email, r.AvatarUrl, r.State, r.CreatedAt, ""), nil
 }
 
 func UserByUsername(ctx context.Context, db *sql.DB, username string) (*User, error) {
@@ -212,5 +222,5 @@ func UserByUsername(ctx context.Context, db *sql.DB, username string) (*User, er
 	if err != nil {
 		return nil, err
 	}
-	return toUser(db, r.ID, r.Username, r.Name, r.Role, r.AvatarUrl, r.State, r.CreatedAt, r.PasswordHash), nil
+	return toUser(db, r.ID, r.Username, r.Name, r.Role, r.Email, r.AvatarUrl, r.State, r.CreatedAt, r.PasswordHash), nil
 }

internal/store/vote.go

@@ -5,6 +5,7 @@ import (
 	"database/sql"
 	"errors"
 	"fmt"
+	"strings"
 
 	"github.com/jackc/pgx/v5/pgconn"
 
@@ -14,6 +15,9 @@ import (
 // ErrDuplicateUsername is returned when inserting a username that already exists.
 var ErrDuplicateUsername = errors.New("username taken")
 
+// ErrDuplicateEmail is returned when inserting/updating an email that already exists.
+var ErrDuplicateEmail = errors.New("email taken")
+
 // ErrHiddenOrMissing is returned when voting on a hidden or unknown question.
 var ErrHiddenOrMissing = errors.New("question not votable")
 
@@ -58,6 +62,9 @@ func Vote(ctx context.Context, db *sql.DB, userID, questionID string, value int)
 func mapUniqueViolation(err error) error {
 	var pgErr *pgconn.PgError
 	if errors.As(err, &pgErr) && pgErr.Code == "23505" {
+		if strings.Contains(strings.ToLower(pgErr.ConstraintName), "email") {
+			return ErrDuplicateEmail
+		}
 		return ErrDuplicateUsername
 	}
 	return err

internal/web/auth.go

@@ -129,14 +129,21 @@ func (s *Server) handleRegister(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	username := strings.TrimSpace(r.PostFormValue("username"))
+	emailRaw := r.PostFormValue("email")
 	password := r.PostFormValue("password")
 	setupSecret := r.PostFormValue("setup_secret")
-	p := authPage{page: s.basePage(r, "Create account"), Username: username}
+	p := authPage{page: s.basePage(r, "Create account"), Username: username, Email: strings.TrimSpace(emailRaw)}
 	if !usernameRe.MatchString(username) {
 		p.Error = "Username must be 3–20 letters, numbers, or underscores."
 		s.exec(w, "register", p)
 		return
 	}
+	email, emailErr := store.ValidateEmail(emailRaw)
+	if emailErr != "" {
+		p.Error = emailErr
+		s.exec(w, "register", p)
+		return
+	}
 	if ok, msg := passwordValid(password); !ok {
 		p.Error = msg
 		s.exec(w, "register", p)
@@ -153,6 +160,7 @@ func (s *Server) handleRegister(w http.ResponseWriter, r *http.Request) {
 	}
 	u := &store.User{
 		Username:     username,
+		Email:        email,
 		PasswordHash: string(hash),
 		Role:         role,
 	}
@@ -162,6 +170,11 @@ func (s *Server) handleRegister(w http.ResponseWriter, r *http.Request) {
 			s.exec(w, "register", p)
 			return
 		}
+		if errors.Is(err, store.ErrDuplicateEmail) {
+			p.Error = "That email is already registered."
+			s.exec(w, "register", p)
+			return
+		}
 		log.Printf("register create: %v", err)
 		http.Error(w, "could not create account", http.StatusInternalServerError)
 		return

internal/web/profile.go

@@ -2,6 +2,7 @@ package web
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"image"
 	"image/jpeg"
@@ -27,6 +28,7 @@ type profilePage struct {
 	UploadsEnabled bool
 	Error          string
 	StateVal       string
+	EmailVal       string
 }
 
 func (s *Server) handleProfileForm(w http.ResponseWriter, r *http.Request) {
@@ -35,7 +37,7 @@ func (s *Server) handleProfileForm(w http.ResponseWriter, r *http.Request) {
 		http.Redirect(w, r, "/login?next=/profile", http.StatusSeeOther)
 		return
 	}
-	s.renderProfile(w, r, u, "", u.State)
+	s.renderProfile(w, r, u, "", u.State, u.Email)
 }
 
 func (s *Server) handleProfile(w http.ResponseWriter, r *http.Request) {
@@ -45,7 +47,7 @@ func (s *Server) handleProfile(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	if err := r.ParseMultipartForm(3 << 20); err != nil {
-		s.renderProfile(w, r, u, "Could not read form (max 2MB for images).", u.State)
+		s.renderProfile(w, r, u, "Could not read form (max 2MB for images).", u.State, u.Email)
 		return
 	}
 	want := s.sessions.GetString(r.Context(), "csrf")
@@ -57,7 +59,12 @@ func (s *Server) handleProfile(w http.ResponseWriter, r *http.Request) {
 
 	state := geo.NormalizeState(r.FormValue("state"))
 	if !geo.ValidState(state) {
-		s.renderProfile(w, r, u, "Choose a valid US state or leave it blank.", state)
+		s.renderProfile(w, r, u, "Choose a valid US state or leave it blank.", state, r.FormValue("email"))
+		return
+	}
+	email, emailErr := store.ValidateEmail(r.FormValue("email"))
+	if emailErr != "" {
+		s.renderProfile(w, r, u, emailErr, state, r.FormValue("email"))
 		return
 	}
 
@@ -67,16 +74,16 @@ func (s *Server) handleProfile(w http.ResponseWriter, r *http.Request) {
 	if err == nil {
 		defer file.Close()
 		if !s.cfg.Blob.Enabled() {
-			s.renderProfile(w, r, u, "Avatar uploads are not configured on this server.", state)
+			s.renderProfile(w, r, u, "Avatar uploads are not configured on this server.", state, email)
 			return
 		}
 		if hdr.Size > 2<<20 {
-			s.renderProfile(w, r, u, "Avatar must be 2MB or smaller.", state)
+			s.renderProfile(w, r, u, "Avatar must be 2MB or smaller.", state, email)
 			return
 		}
 		body, ext, contentType, prepErr := prepareAvatar(file, 2<<20)
 		if prepErr != nil {
-			s.renderProfile(w, r, u, "Avatar must be a JPEG, PNG, or WebP image.", state)
+			s.renderProfile(w, r, u, "Avatar must be a JPEG, PNG, or WebP image.", state, email)
 			return
 		}
 		prevURL := u.AvatarURL
@@ -88,14 +95,19 @@ func (s *Server) handleProfile(w http.ResponseWriter, r *http.Request) {
 			Size:        int64(len(body)),
 		})
 		if upErr != nil {
-			s.renderProfile(w, r, u, "Could not upload avatar. Try again later.", state)
+			s.renderProfile(w, r, u, "Could not upload avatar. Try again later.", state, email)
 			return
 		}
 		avatarURL = url
 		u.State = state
+		u.Email = email
 		u.AvatarURL = avatarURL
 		if err := s.store.SaveUserProfile(r.Context(), u); err != nil {
 			_ = s.cfg.Blob.Delete(r.Context(), avatarKey)
+			if errors.Is(err, store.ErrDuplicateEmail) {
+				s.renderProfile(w, r, u, "That email is already registered.", state, email)
+				return
+			}
 			http.Error(w, "could not save profile", http.StatusInternalServerError)
 			return
 		}
@@ -106,12 +118,17 @@ func (s *Server) handleProfile(w http.ResponseWriter, r *http.Request) {
 		http.Redirect(w, r, "/profile", http.StatusSeeOther)
 		return
 	} else if err != http.ErrMissingFile {
-		s.renderProfile(w, r, u, "Could not read avatar file.", state)
+		s.renderProfile(w, r, u, "Could not read avatar file.", state, email)
 		return
 	}
 
 	u.State = state
+	u.Email = email
 	if err := s.store.SaveUserProfile(r.Context(), u); err != nil {
+		if errors.Is(err, store.ErrDuplicateEmail) {
+			s.renderProfile(w, r, u, "That email is already registered.", state, email)
+			return
+		}
 		http.Error(w, "could not save profile", http.StatusInternalServerError)
 		return
 	}
@@ -236,7 +253,7 @@ func fitAvatar(img image.Image, maxDim int) image.Image {
 	return dst
 }
 
-func (s *Server) renderProfile(w http.ResponseWriter, r *http.Request, u *store.User, errMsg, stateVal string) {
+func (s *Server) renderProfile(w http.ResponseWriter, r *http.Request, u *store.User, errMsg, stateVal, emailVal string) {
 	var (
 		questions []store.RankedQuestion
 		label     string
@@ -263,5 +280,6 @@ func (s *Server) renderProfile(w http.ResponseWriter, r *http.Request, u *store.
 		UploadsEnabled: s.cfg.Blob.Enabled(),
 		Error:          errMsg,
 		StateVal:       stateVal,
+		EmailVal:       emailVal,
 	})
 }

internal/web/server.go

@@ -22,6 +22,7 @@ import (
 
 	"plumber/internal/blob"
 	"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
 }
 
 type Server struct {
@@ -82,6 +84,7 @@ type submitPage struct {
 type authPage struct {
 	page
 	Username string
+	Email    string
 	Error    string
 	Next     string
 }
@@ -98,6 +101,9 @@ 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{}
+	}
 	funcMap := template.FuncMap{
 		"voteCtx": func(user *store.User, csrf, view, date string, q store.RankedQuestion) voteCtx {
 			return voteCtx{User: user, CSRF: csrf, View: view, Date: date, Question: q}
@@ -482,6 +488,17 @@ func (s *Server) handleAnswer(w http.ResponseWriter, r *http.Request) {
 	if len(body) > 12000 {
 		body = truncateRunes(body, 12000)
 	}
+	q, err := s.store.GetQuestion(r.Context(), id, u.ID)
+	if err != nil {
+		http.NotFound(w, r)
+		return
+	}
+	_, priorErr := s.store.GetAnswer(r.Context(), id)
+	wasNew := errors.Is(priorErr, sql.ErrNoRows)
+	if priorErr != nil && !wasNew {
+		http.Error(w, "could not load answer", http.StatusInternalServerError)
+		return
+	}
 	ans := &store.Answer{
 		QuestionID: id,
 		AuthorID:   u.ID,
@@ -491,6 +508,9 @@ func (s *Server) handleAnswer(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "could not save answer", http.StatusInternalServerError)
 		return
 	}
+	if wasNew {
+		s.notifyQuestionAnswered(q, body, u.ID)
+	}
 	saved, err := s.store.GetAnswer(r.Context(), id)
 	if err != nil {
 		http.Error(w, "could not load answer", http.StatusInternalServerError)
@@ -503,6 +523,30 @@ func (s *Server) handleAnswer(w http.ResponseWriter, r *http.Request) {
 	http.Redirect(w, r, "/questions/"+url.PathEscape(id), http.StatusSeeOther)
 }
 
+func (s *Server) notifyQuestionAnswered(q *store.RankedQuestion, answerBody, adminID string) {
+	if q == nil || s.cfg.Mail == nil {
+		return
+	}
+	author, err := s.store.UserByID(context.Background(), q.AuthorID)
+	if err != nil || author == nil || author.Email == "" || author.ID == adminID {
+		return
+	}
+	msg := mail.QuestionAnswered{
+		ToEmail:       author.Email,
+		ToName:        author.Name,
+		QuestionID:    q.ID,
+		QuestionTitle: q.Title,
+		AnswerBody:    answerBody,
+	}
+	go func() {
+		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+		if err := s.cfg.Mail.NotifyQuestionAnswered(ctx, msg); err != nil {
+			log.Printf("notify answer %s: %v", q.ID, err)
+		}
+	}()
+}
+
 func (s *Server) handleHide(w http.ResponseWriter, r *http.Request) {
 	if !s.requireCSRF(w, r) {
 		return

internal/web/server_test.go

@@ -19,6 +19,7 @@ import (
 
 	"plumber"
 	"plumber/internal/blob"
+	"plumber/internal/mail"
 	"plumber/internal/pacific"
 	"plumber/internal/store"
 )
@@ -53,6 +54,7 @@ func seedUser(t *testing.T, st store.Store, username, password string, role stor
 	}
 	u := &store.User{
 		Username:     username,
+		Email:        username + "@example.com",
 		PasswordHash: string(hash),
 		Role:         role,
 	}
@@ -114,7 +116,7 @@ func registerUser(t *testing.T, h http.Handler, username, password string, setup
 	pre := rec.Result().Cookies()
 	preToken := sessionValue(pre)
 	csrf := csrfFrom(rec.Body.String())
-	form := "_csrf=" + csrf + "&username=" + username + "&password=" + password
+	form := "_csrf=" + csrf + "&username=" + username + "&email=" + username + "%40example.com&password=" + password
 	if len(setupSecret) > 0 && setupSecret[0] != "" {
 		form += "&setup_secret=" + setupSecret[0]
 	}
@@ -362,6 +364,7 @@ func TestProfilePageAndState(t *testing.T) {
 	var buf bytes.Buffer
 	w := multipart.NewWriter(&buf)
 	_ = w.WriteField("_csrf", csrf)
+	_ = w.WriteField("email", name+"@example.com")
 	_ = w.WriteField("state", "CA")
 	_ = w.Close()
 	req = httptest.NewRequest(http.MethodPost, "/profile", &buf)
@@ -389,6 +392,7 @@ func TestProfilePageAndState(t *testing.T) {
 	buf.Reset()
 	w = multipart.NewWriter(&buf)
 	_ = w.WriteField("_csrf", csrf)
+	_ = w.WriteField("email", name+"@example.com")
 	_ = w.WriteField("state", "ZZ")
 	_ = w.Close()
 	req = httptest.NewRequest(http.MethodPost, "/profile", &buf)
@@ -449,6 +453,7 @@ func TestProfileAdminAnsweredListAndAvatarUpload(t *testing.T) {
 	var buf bytes.Buffer
 	w := multipart.NewWriter(&buf)
 	_ = w.WriteField("_csrf", csrf)
+	_ = w.WriteField("email", hubName+"@example.com")
 	_ = w.WriteField("state", "OR")
 	part, err := w.CreateFormFile("avatar", "pic.png")
 	if err != nil {
@@ -666,6 +671,133 @@ func csrfFrom(html string) string {
 	return html[:j]
 }
 
+func TestRegisterRequiresEmail(t *testing.T) {
+	srv, _ := newTestServer(t, Config{})
+	h := srv.Handler()
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/register", nil))
+	csrf := csrfFrom(rec.Body.String())
+	cookies := rec.Result().Cookies()
+	form := strings.NewReader("_csrf=" + csrf + "&username=" + uniq("noem") + "&email=bad&password=hunter22")
+	req := httptest.NewRequest(http.MethodPost, "/register", form)
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	for _, c := range cookies {
+		req.AddCookie(c)
+	}
+	rec = httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	if rec.Code != 200 || !strings.Contains(rec.Body.String(), "valid email") {
+		t.Fatalf("want email validation error, got %d %s", rec.Code, rec.Body.String())
+	}
+}
+
+func TestAnswerNotifyFirstOnly(t *testing.T) {
+	recMail := &mail.Recording{}
+	srv, mem := newTestServer(t, Config{Mail: recMail})
+	h := srv.Handler()
+	adminName := uniq("adm")
+	askName := uniq("ask")
+	admin := seedUser(t, mem, adminName, "hunter22", store.RoleAdmin)
+	asker := seedUser(t, mem, askName, "hunter22", store.RoleUser)
+	adminCookies := loginUser(t, h, adminName, "hunter22")
+
+	q := &store.RankedQuestion{
+		AuthorID: asker.ID,
+		Title:    "Leaky sink",
+		Body:     "Drip",
+		City:     "Oakland",
+		HuntDate: pacific.Today(),
+	}
+	if err := mem.CreateQuestion(context.Background(), q); err != nil {
+		t.Fatal(err)
+	}
+
+	postAnswer := func(body string) {
+		t.Helper()
+		w := httptest.NewRecorder()
+		req := httptest.NewRequest(http.MethodGet, "/questions/"+q.ID, nil)
+		for _, c := range adminCookies {
+			req.AddCookie(c)
+		}
+		h.ServeHTTP(w, req)
+		csrf := csrfFrom(w.Body.String())
+		form := strings.NewReader("_csrf=" + csrf + "&body=" + body)
+		req = httptest.NewRequest(http.MethodPost, "/questions/"+q.ID+"/answer", form)
+		req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+		req.Header.Set("HX-Request", "true")
+		for _, c := range adminCookies {
+			req.AddCookie(c)
+		}
+		w = httptest.NewRecorder()
+		h.ServeHTTP(w, req)
+		if w.Code != 200 {
+			t.Fatalf("answer %d %s", w.Code, w.Body.String())
+		}
+	}
+
+	postAnswer("First+reply")
+	deadline := time.Now().Add(2 * time.Second)
+	var msgs []mail.QuestionAnswered
+	for time.Now().Before(deadline) {
+		msgs = recMail.Snapshot()
+		if len(msgs) > 0 {
+			break
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+	if len(msgs) != 1 {
+		t.Fatalf("first answer notifies once, got %d", len(msgs))
+	}
+	if msgs[0].ToEmail != asker.Email || msgs[0].QuestionID != q.ID {
+		t.Fatalf("unexpected notify: %+v", msgs[0])
+	}
+	if msgs[0].AnswerBody != "First reply" {
+		t.Fatalf("answer body %q", msgs[0].AnswerBody)
+	}
+
+	postAnswer("Edited+reply")
+	time.Sleep(50 * time.Millisecond)
+	if recMail.Len() != 1 {
+		t.Fatalf("edit must not notify again, got %d", recMail.Len())
+	}
+
+	// Author without email is skipped
+	recMail2 := &mail.Recording{}
+	srv2, mem2 := newTestServer(t, Config{Mail: recMail2})
+	h2 := srv2.Handler()
+	admin2 := seedUser(t, mem2, uniq("adm2"), "hunter22", store.RoleAdmin)
+	noMail := &store.User{Username: uniq("silent"), PasswordHash: admin.PasswordHash, Role: store.RoleUser, Email: ""}
+	hash, _ := bcrypt.GenerateFromPassword([]byte("hunter22"), bcrypt.MinCost)
+	noMail.PasswordHash = string(hash)
+	if err := mem2.CreateUser(context.Background(), noMail); err != nil {
+		t.Fatal(err)
+	}
+	q2 := &store.RankedQuestion{AuthorID: noMail.ID, Title: "Quiet", Body: "x", HuntDate: pacific.Today()}
+	if err := mem2.CreateQuestion(context.Background(), q2); err != nil {
+		t.Fatal(err)
+	}
+	cookies := loginUser(t, h2, admin2.Username, "hunter22")
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/questions/"+q2.ID, nil)
+	for _, c := range cookies {
+		req.AddCookie(c)
+	}
+	h2.ServeHTTP(w, req)
+	csrf := csrfFrom(w.Body.String())
+	form := strings.NewReader("_csrf=" + csrf + "&body=Hello")
+	req = httptest.NewRequest(http.MethodPost, "/questions/"+q2.ID+"/answer", form)
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	for _, c := range cookies {
+		req.AddCookie(c)
+	}
+	w = httptest.NewRecorder()
+	h2.ServeHTTP(w, req)
+	time.Sleep(50 * time.Millisecond)
+	if recMail2.Len() != 0 {
+		t.Fatalf("empty email must skip notify, got %d", recMail2.Len())
+	}
+}
+
 // TestRegisterThrottleUsesTCPPeerThroughRouter ensures forged X-Forwarded-For
 // cannot bypass rate limits when the direct peer is outside TrustedProxies.
 // This must go through Handler() so middleware ordering bugs are caught.

schema.sql

@@ -4,11 +4,16 @@ CREATE TABLE IF NOT EXISTS users (
   name TEXT NOT NULL,
   password_hash TEXT NOT NULL,
   role TEXT NOT NULL DEFAULT 'user' CHECK (role IN ('user', 'admin')),
+  email TEXT NOT NULL DEFAULT '',
   avatar_url TEXT NOT NULL DEFAULT '',
   state TEXT NOT NULL DEFAULT '',
   created_at TEXT NOT NULL
 );
 
+CREATE UNIQUE INDEX IF NOT EXISTS users_email_lower_uidx
+  ON users (lower(email))
+  WHERE email <> '';
+
 CREATE TABLE IF NOT EXISTS questions (
   id TEXT PRIMARY KEY,
   author_id TEXT NOT NULL REFERENCES users(id),

templates/profile.html

@@ -25,6 +25,10 @@
       </div>
     </div>
 
+    <label for="email">Email</label>
+    <input id="email" name="email" type="email" required maxlength="254" autocomplete="email" value="{{.EmailVal}}">
+    <p class="hint">Required. We’ll email you when a plumber answers your question.</p>
+
     <label for="state">State</label>
     <select id="state" name="state">
       <option value=""{{if eq .StateVal ""}} selected{{end}}>Prefer not to say</option>

templates/register.html

@@ -9,6 +9,9 @@
     <label for="username">Username</label>
     <input id="username" name="username" type="text" required minlength="3" maxlength="20" pattern="[A-Za-z0-9_]+" autocomplete="username" autocapitalize="off" spellcheck="false" value="{{.Username}}">
     <p class="hint">3–20 letters, numbers, or underscores.</p>
+    <label for="email">Email</label>
+    <input id="email" name="email" type="email" required maxlength="254" autocomplete="email" value="{{.Email}}">
+    <p class="hint">We’ll email you when a plumber answers your question.</p>
     <label for="password">Password</label>
     <input id="password" name="password" type="password" required minlength="8" maxlength="72" autocomplete="new-password">
     <p class="hint">At least 8 characters (max 72 bytes).</p>