diff --git a/cmd/server/main.go b/cmd/server/main.go
index ba295cd..20f434e 100644
--- a/cmd/server/main.go
+++ b/cmd/server/main.go
@@ -17,6 +17,7 @@ import (
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/ai/harness"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/ai/skills"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/auth"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/chat"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/config"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/dinners"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/forwarded"
@@ -156,6 +157,13 @@ func run(cfg config.Config, logger *slog.Logger) error {
 	if err := notifier.Register(notify.ChannelPush, pushSender); err != nil {
 		return err
 	}
+	chatSvc, err := chat.NewService(db, box, cfg.PublicURL, http.DefaultTransport)
+	if err != nil {
+		return err
+	}
+	if err := notifier.Register(notify.ChannelChat, chatSvc); err != nil {
+		return err
+	}
 
 	sessions, err := auth.NewSessionManager(db, cfg.SessionIdle, cfg.SessionMax)
 	if err != nil {
@@ -173,7 +181,7 @@ func run(cfg config.Config, logger *slog.Logger) error {
 		return err
 	}
 
-	router, err := server.NewRouter(logger, version, cfg.TrustedProxy, authFlow, sessions, settings, search, ai, dinnerSvc, suggestSvc, planSvc, shopSvc, googleSvc, pushSvc, runner, photos, frontend.Assets())
+	router, err := server.NewRouter(logger, version, cfg.TrustedProxy, authFlow, sessions, settings, search, ai, chatSvc, dinnerSvc, suggestSvc, planSvc, shopSvc, googleSvc, pushSvc, runner, photos, frontend.Assets())
 	if err != nil {
 		return err
 	}
diff --git a/docs/ARCHITECTURE.md b/docs/ARCHITECTURE.md
index 5971111..7e1ccff 100644
--- a/docs/ARCHITECTURE.md
+++ b/docs/ARCHITECTURE.md
@@ -684,6 +684,46 @@ Runs are recorded in `schedule_runs` and executed through `jobs`.
     `{"endpoint"}` and answers 204 whether or not it was stored.
   - An invalid body is 400 `invalid_request` (not a JSON object of the
     known fields) or `invalid_subscription` (a field fails validation).
+- `internal/chat` keeps the Google Chat incoming webhook in `chat_settings`
+  and is the outbox's sender for the `chat` channel. The webhook URL holds
+  its own key and token, so it is sealed with `secretbox` in
+  `webhook_url_ct` and never appears in a response, log line or error.
+  Under the signed-in `/api/v1`:
+  - `PUT /api/v1/settings/chat-webhook` (CSRF-checked) takes
+    `{"url", "space_label"}`, both required. The URL must be exactly
+    `https://chat.googleapis.com/v1/spaces/{space}/messages?key=…&token=…`:
+    that scheme and host spelled so, no port or user info, the space id
+    letters, digits, `-` or `_`, and only the query parameters `key` and
+    `token`, each once and at least 16 characters. The space label is 1–100
+    characters. A refused body is 400 `invalid_request` (not a JSON object
+    of the two fields) or `invalid_webhook`. Saving replaces any stored
+    webhook and clears its test outcome.
+  - `GET /api/v1/settings/chat-webhook` answers `{configured, space_label,
+    url_masked, last_test_at, last_test_status, updated_at}`; `url_masked`
+    shows the space id and only the last four characters of the decoded
+    token (`…/spaces/AAQA…/messages?key=…&token=…ZxQ=`). Absent values are
+    `null`.
+  - `POST /api/v1/settings/chat-webhook/test` (CSRF-checked) posts
+    "MealQuest · test message", unthreaded, and records `last_test_at` and
+    `last_test_status` (`ok` for 2xx, else `failed`). Whatever status Google
+    Chat answers, it answers 200 with that status as `http_status` and the
+    settings as GET gives them. No webhook stored is 409 `not_configured`;
+    a webhook replaced during the test is 409 `webhook_changed`; no answer
+    from Google Chat is recorded as failed and answered 502
+    `chat_unreachable`.
+  - A notification is posted as `{"text"}`, plus `cardsV2` with an "Open"
+    button to the payload's path under `MEALQUEST_PUBLIC_URL` for
+    `plan_ready` and `list_ready`, with `threadKey=mealquest-week-YYYY-Www`
+    (the ISO week of the payload's week) and
+    `messageReplyOption=REPLY_MESSAGE_FALLBACK_TO_NEW_THREAD`; a payload
+    with no week is posted unthreaded. 2xx is sent; 429, 5xx or no answer
+    is retried by the outbox; any other status, or no webhook stored, fails
+    the row at once (`notify.ErrUndeliverable`). Redirects are not
+    followed.
+  - The builders in `internal/chat/messages.go` make each event's
+    `notify.Event` (title and body shared with Web Push) and `chat.Text`
+    its Chat message, such as "This week's plan is ready: Tacos, Bolognese,
+    Tikka masala + 4 more. Open the plan →".
 
 ## Google Calendar
 
diff --git a/internal/chat/chat.go b/internal/chat/chat.go
new file mode 100644
index 0000000..4cd09ef
--- /dev/null
+++ b/internal/chat/chat.go
@@ -0,0 +1,459 @@
+// Package chat sends notifications to the household's Google Chat space
+// through its incoming webhook, and keeps that webhook in chat_settings.
+//
+// The webhook URL carries its own key and token, so it is a secret: it is
+// sealed with secretbox in webhook_url_ct and is never returned, logged or
+// put in an error. Only its space label, a masked tail and the outcome of
+// the last test message are shown.
+package chat
+
+import (
+	"bytes"
+	"context"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+	"unicode/utf8"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/db"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/household"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/jobs"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/notify"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/secretbox"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
+)
+
+const (
+	// MaxSpaceLabelChars bounds a space label.
+	MaxSpaceLabelChars = 100
+	// requestTimeout bounds one post to Google Chat.
+	requestTimeout = 15 * time.Second
+	// maxDrainBytes bounds how much of a Google Chat response is read.
+	maxDrainBytes = 4096
+	// replyOption threads a message under its threadKey, starting the
+	// thread when there is none yet.
+	replyOption = "REPLY_MESSAGE_FALLBACK_TO_NEW_THREAD"
+)
+
+// Test outcomes, as chat_settings.last_test_status stores them.
+const (
+	TestOK     = "ok"
+	TestFailed = "failed"
+)
+
+var (
+	// ErrNotConfigured is returned when no webhook is stored.
+	ErrNotConfigured = errors.New("chat: no Google Chat webhook is configured")
+	// ErrUnreachable is wrapped by the error of a post Google Chat did not
+	// answer.
+	ErrUnreachable = errors.New("chat: Google Chat did not answer")
+	// ErrWebhookChanged is returned by Test when the webhook was replaced
+	// while the test message was being sent; nothing is recorded.
+	ErrWebhookChanged = errors.New("chat: the Google Chat webhook changed during the test")
+)
+
+// Settings is the stored webhook as the API shows it: never the URL, only
+// its masked form.
+type Settings struct {
+	Configured bool    `json:"configured"`
+	SpaceLabel *string `json:"space_label"`
+	// URLMasked is the webhook URL without its key and with only the last
+	// few characters of its token.
+	URLMasked *string `json:"url_masked"`
+	// LastTestAt and LastTestStatus ("ok" or "failed") are nil until a
+	// test message is sent to this webhook.
+	LastTestAt     *string `json:"last_test_at"`
+	LastTestStatus *string `json:"last_test_status"`
+	UpdatedAt      *string `json:"updated_at"`
+}
+
+// TestResult is the outcome of a test message.
+type TestResult struct {
+	// HTTPStatus is the status Google Chat answered.
+	HTTPStatus int `json:"http_status"`
+	Settings
+}
+
+// Problem is one invalid field of a webhook update, named by its JSON key.
+type Problem struct {
+	Field  string
+	Reason string
+}
+
+// ValidationError lists every problem with a webhook update. It never
+// quotes the URL.
+type ValidationError struct {
+	Problems []Problem
+}
+
+func (e *ValidationError) Error() string {
+	parts := make([]string, len(e.Problems))
+	for i, p := range e.Problems {
+		parts[i] = p.Field + ": " + p.Reason
+	}
+	return "invalid Google Chat webhook: " + strings.Join(parts, "; ")
+}
+
+// Service keeps the webhook and posts to it. It is the notify.Sender of the
+// chat channel.
+type Service struct {
+	st  *store.Store
+	box *secretbox.Box
+	// publicURL is MEALQUEST_PUBLIC_URL, which a card's "Open" button
+	// links under.
+	publicURL *url.URL
+	client    *http.Client
+	// now is the clock settings are saved and tests recorded on; tests
+	// replace it.
+	now func() time.Time
+}
+
+// NewService returns the service over st, sealing the webhook with box and
+// linking cards under publicURL. Requests go through transport
+// (http.DefaultTransport in production) and never follow a redirect.
+func NewService(st *store.Store, box *secretbox.Box, publicURL *url.URL, transport http.RoundTripper) (*Service, error) {
+	switch {
+	case st == nil:
+		return nil, errors.New("chat: nil store")
+	case box == nil:
+		return nil, errors.New("chat: nil secret box")
+	case publicURL == nil:
+		return nil, errors.New("chat: nil public URL")
+	case transport == nil:
+		return nil, errors.New("chat: nil transport")
+	}
+	return &Service{
+		st:        st,
+		box:       box,
+		publicURL: publicURL,
+		client: &http.Client{
+			Transport: transport,
+			Timeout:   requestTimeout,
+			CheckRedirect: func(*http.Request, []*http.Request) error {
+				return http.ErrUseLastResponse
+			},
+		},
+		now: time.Now,
+	}, nil
+}
+
+// Get returns the stored webhook's settings; Configured is false and every
+// other field nil before one is saved.
+func (s *Service) Get(ctx context.Context) (Settings, error) {
+	row, err := db.New(s.st.Reader).GetChatSettings(ctx)
+	if errors.Is(err, sql.ErrNoRows) {
+		return Settings{}, nil
+	}
+	if err != nil {
+		return Settings{}, fmt.Errorf("chat: read chat settings: %w", err)
+	}
+	hook, err := s.open(row)
+	if err != nil {
+		return Settings{}, err
+	}
+	return settingsFrom(row, hook), nil
+}
+
+// Put validates rawURL and spaceLabel and stores them, replacing any
+// webhook stored before and clearing its test outcome. Every problem is
+// reported in a *ValidationError.
+func (s *Service) Put(ctx context.Context, rawURL, spaceLabel string) (Settings, error) {
+	var problems []Problem
+	hook, err := ParseWebhook(rawURL)
+	if err != nil {
+		problems = append(problems, Problem{"url", err.Error()})
+	}
+	label := strings.TrimSpace(spaceLabel)
+	switch {
+	case label == "":
+		problems = append(problems, Problem{"space_label", "is required"})
+	case utf8.RuneCountInString(label) > MaxSpaceLabelChars:
+		problems = append(problems, Problem{"space_label", fmt.Sprintf("must be at most %d characters", MaxSpaceLabelChars)})
+	case strings.ContainsFunc(label, func(r rune) bool { return r < ' ' || r == 0x7f }):
+		problems = append(problems, Problem{"space_label", "must not contain control characters"})
+	}
+	if len(problems) > 0 {
+		return Settings{}, &ValidationError{Problems: problems}
+	}
+	ct, err := s.box.Encrypt([]byte(hook.String()))
+	if err != nil {
+		return Settings{}, fmt.Errorf("chat: seal webhook: %w", err)
+	}
+
+	var saved db.ChatSetting
+	err = s.st.WithTx(ctx, func(tx *sql.Tx) error {
+		q := db.New(tx)
+		row, err := q.GetChatSettings(ctx)
+		if err != nil && !errors.Is(err, sql.ErrNoRows) {
+			return fmt.Errorf("chat: read chat settings: %w", err)
+		}
+		now := s.timestamp()
+		created := now
+		if err == nil {
+			created = row.CreatedAt
+		}
+		saved, err = q.UpsertChatSettings(ctx, db.UpsertChatSettingsParams{
+			WebhookUrlCt: ct,
+			SpaceLabel:   sql.NullString{String: label, Valid: true},
+			CreatedAt:    created,
+			UpdatedAt:    now,
+		})
+		if err != nil {
+			return fmt.Errorf("chat: save chat settings: %w", err)
+		}
+		return nil
+	})
+	if err != nil {
+		return Settings{}, err
+	}
+	return settingsFrom(saved, hook), nil
+}
+
+// Test posts TestText to the stored webhook, unthreaded, and records when
+// and whether Google Chat accepted it. A status Google Chat answers is a
+// TestResult, whatever it is; a request that gets no answer is recorded as
+// failed and returned as an error. A test cut short by ctx records nothing.
+func (s *Service) Test(ctx context.Context) (TestResult, error) {
+	row, err := db.New(s.st.Reader).GetChatSettings(ctx)
+	if errors.Is(err, sql.ErrNoRows) {
+		return TestResult{}, ErrNotConfigured
+	}
+	if err != nil {
+		return TestResult{}, fmt.Errorf("chat: read chat settings: %w", err)
+	}
+	hook, err := s.open(row)
+	if err != nil {
+		return TestResult{}, err
+	}
+	status, postErr := s.post(ctx, hook, message{Text: TestText}, "")
+	if err := ctx.Err(); err != nil {
+		return TestResult{}, err
+	}
+	outcome := TestFailed
+	if postErr == nil && status >= 200 && status < 300 {
+		outcome = TestOK
+	}
+	at := s.timestamp()
+	write, cancel := jobs.FinalWriteContext(ctx)
+	defer cancel()
+	n, err := db.New(s.st.Writer).RecordChatTest(write, db.RecordChatTestParams{
+		LastTestAt:     sql.NullString{String: at, Valid: true},
+		LastTestStatus: sql.NullString{String: outcome, Valid: true},
+		UpdatedAt:      at,
+		WebhookUrlCt:   row.WebhookUrlCt,
+	})
+	if err != nil {
+		return TestResult{}, fmt.Errorf("chat: record test: %w", err)
+	}
+	if n != 1 {
+		return TestResult{}, ErrWebhookChanged
+	}
+	if postErr != nil {
+		return TestResult{}, postErr
+	}
+	row.LastTestAt = sql.NullString{String: at, Valid: true}
+	row.LastTestStatus = sql.NullString{String: outcome, Valid: true}
+	row.UpdatedAt = at
+	return TestResult{HTTPStatus: status, Settings: settingsFrom(row, hook)}, nil
+}
+
+// Send posts m to the stored webhook, threaded by the week of its payload,
+// and is the chat channel's notify.Sender. Google Chat answering 2xx is
+// success; 429 or 5xx, or no answer at all, is an error the outbox
+// retries; any other status, or no webhook stored, wraps
+// notify.ErrUndeliverable so the row fails at once.
+func (s *Service) Send(ctx context.Context, m notify.Message) error {
+	row, err := db.New(s.st.Reader).GetChatSettings(ctx)
+	if errors.Is(err, sql.ErrNoRows) {
+		return fmt.Errorf("%w: %w", notify.ErrUndeliverable, ErrNotConfigured)
+	}
+	if err != nil {
+		return fmt.Errorf("chat: read chat settings: %w", err)
+	}
+	hook, err := s.open(row)
+	if err != nil {
+		return err
+	}
+	msg, err := s.messageOf(m.Payload)
+	if err != nil {
+		return fmt.Errorf("%w: chat: %w", notify.ErrUndeliverable, err)
+	}
+	var thread string
+	if m.Payload.Week != "" {
+		week, err := store.ParseLocalDate(m.Payload.Week)
+		if err != nil {
+			return fmt.Errorf("%w: chat: payload week: %w", notify.ErrUndeliverable, err)
+		}
+		thread = ThreadKey(week)
+	}
+	status, err := s.post(ctx, hook, msg, thread)
+	switch {
+	case err != nil:
+		return err
+	case status >= 200 && status < 300:
+		return nil
+	case status == http.StatusTooManyRequests || status >= 500:
+		return fmt.Errorf("chat: Google Chat answered status %d", status)
+	default:
+		return fmt.Errorf("%w: chat: Google Chat refused the message with status %d", notify.ErrUndeliverable, status)
+	}
+}
+
+// ThreadKey is the Chat thread of the week starting on week, such as
+// "mealquest-week-2026-W42": every message about a week goes in one thread.
+func ThreadKey(week store.LocalDate) string {
+	return "mealquest-week-" + household.PeriodKey(week)
+}
+
+// message is the body of a Google Chat webhook post.
+type message struct {
+	Text    string   `json:"text"`
+	CardsV2 []cardV2 `json:"cardsV2,omitempty"`
+}
+
+type cardV2 struct {
+	CardID string `json:"cardId"`
+	Card   card   `json:"card"`
+}
+
+type card struct {
+	Header   cardHeader    `json:"header"`
+	Sections []cardSection `json:"sections"`
+}
+
+type cardHeader struct {
+	Title    string `json:"title"`
+	Subtitle string `json:"subtitle,omitempty"`
+}
+
+type cardSection struct {
+	Widgets []cardWidget `json:"widgets"`
+}
+
+type cardWidget struct {
+	ButtonList buttonList `json:"buttonList"`
+}
+
+type buttonList struct {
+	Buttons []button `json:"buttons"`
+}
+
+type button struct {
+	Text    string  `json:"text"`
+	OnClick onClick `json:"onClick"`
+}
+
+type onClick struct {
+	OpenLink openLink `json:"openLink"`
+}
+
+type openLink struct {
+	URL string `json:"url"`
+}
+
+// messageOf is the Chat message of p: its Text and, for a plan or Supply
+// run, a card whose "Open" button links to p.URL under the public URL.
+func (s *Service) messageOf(p notify.Payload) (message, error) {
+	msg := message{Text: Text(p)}
+	if !carded[p.Event] {
+		return msg, nil
+	}
+	ref, err := url.Parse(p.URL)
+	if err != nil || ref.Scheme != "" || ref.Host != "" || !strings.HasPrefix(p.URL, "/") {
+		return message{}, fmt.Errorf("payload url %q is not an app path", p.URL)
+	}
+	link := s.publicURL.ResolveReference(ref)
+	msg.CardsV2 = []cardV2{{
+		CardID: string(p.Event),
+		Card: card{
+			Header: cardHeader{Title: p.Title, Subtitle: p.Body},
+			Sections: []cardSection{{Widgets: []cardWidget{{ButtonList: buttonList{Buttons: []button{{
+				Text:    "Open",
+				OnClick: onClick{OpenLink: openLink{URL: link.String()}},
+			}}}}}}},
+		},
+	}}
+	return msg, nil
+}
+
+// post sends msg to hook, in thread when it is not empty, and returns the
+// status Google Chat answered. Its error never quotes the webhook URL.
+func (s *Service) post(ctx context.Context, hook Webhook, msg message, thread string) (int, error) {
+	body, err := json.Marshal(msg)
+	if err != nil {
+		return 0, fmt.Errorf("chat: encode message: %w", err)
+	}
+	target, err := url.Parse(hook.String())
+	if err != nil {
+		return 0, errors.New("chat: stored webhook URL does not parse")
+	}
+	if thread != "" {
+		q := target.Query()
+		q.Set("threadKey", thread)
+		q.Set("messageReplyOption", replyOption)
+		target.RawQuery = q.Encode()
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, target.String(), bytes.NewReader(body))
+	if err != nil {
+		return 0, errors.New("chat: build request to the webhook")
+	}
+	req.Header.Set("Content-Type", "application/json; charset=UTF-8")
+	resp, err := s.client.Do(req)
+	if err != nil {
+		// A *url.Error quotes the request URL, the webhook; keep only its
+		// cause.
+		var ue *url.Error
+		if errors.As(err, &ue) {
+			return 0, fmt.Errorf("%w: %w", ErrUnreachable, ue.Err)
+		}
+		return 0, ErrUnreachable
+	}
+	defer resp.Body.Close()
+	// The status is the outcome; the body is read only so the connection
+	// can be reused.
+	io.CopyN(io.Discard, resp.Body, maxDrainBytes)
+	return resp.StatusCode, nil
+}
+
+// open decrypts and validates the stored webhook. Its error never quotes
+// the URL.
+func (s *Service) open(row db.ChatSetting) (Webhook, error) {
+	raw, err := s.box.Decrypt(row.WebhookUrlCt)
+	if err != nil {
+		return Webhook{}, fmt.Errorf("chat: open stored webhook: %w", err)
+	}
+	hook, err := ParseWebhook(string(raw))
+	if err != nil {
+		return Webhook{}, fmt.Errorf("chat: stored webhook URL is invalid: %w", err)
+	}
+	return hook, nil
+}
+
+func (s *Service) timestamp() string {
+	return store.Timestamp{Time: s.now().UTC().Truncate(time.Millisecond)}.String()
+}
+
+func settingsFrom(row db.ChatSetting, hook Webhook) Settings {
+	masked, updated := hook.Masked(), row.UpdatedAt
+	return Settings{
+		Configured:     true,
+		SpaceLabel:     nullString(row.SpaceLabel),
+		URLMasked:      &masked,
+		LastTestAt:     nullString(row.LastTestAt),
+		LastTestStatus: nullString(row.LastTestStatus),
+		UpdatedAt:      &updated,
+	}
+}
+
+func nullString(s sql.NullString) *string {
+	if !s.Valid {
+		return nil
+	}
+	return &s.String
+}
diff --git a/internal/chat/chat_test.go b/internal/chat/chat_test.go
new file mode 100644
index 0000000..ce75072
--- /dev/null
+++ b/internal/chat/chat_test.go
@@ -0,0 +1,530 @@
+package chat
+
+import (
+	"bytes"
+	"context"
+	"crypto/rand"
+	"database/sql"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/db"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/household"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/notify"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/secretbox"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/migrations"
+)
+
+// posted is one request the fake Chat endpoint received.
+type posted struct {
+	Method, Host, Path string
+	Query              url.Values
+	ContentType        string
+	Body               map[string]any
+}
+
+// fakeChat is an httptest Google Chat endpoint answering status.
+type fakeChat struct {
+	srv *httptest.Server
+	mu  sync.Mutex
+	// status is what it answers.
+	status int
+	got    []posted
+}
+
+func newFakeChat(t *testing.T) *fakeChat {
+	t.Helper()
+	f := &fakeChat{status: http.StatusOK}
+	f.srv = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		data, _ := io.ReadAll(r.Body)
+		var body map[string]any
+		if err := json.Unmarshal(data, &body); err != nil {
+			t.Errorf("Chat endpoint body %q: %v", data, err)
+		}
+		f.mu.Lock()
+		f.got = append(f.got, posted{r.Method, r.Host, r.URL.Path, r.URL.Query(), r.Header.Get("Content-Type"), body})
+		status := f.status
+		f.mu.Unlock()
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(status)
+		w.Write([]byte(`{}`))
+	}))
+	t.Cleanup(f.srv.Close)
+	return f
+}
+
+func (f *fakeChat) setStatus(status int) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.status = status
+}
+
+func (f *fakeChat) requests() []posted {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	return append([]posted(nil), f.got...)
+}
+
+// redirectTo sends every request to the server at target, keeping its path
+// and query, as if it were chat.googleapis.com.
+type redirectTo struct {
+	target *url.URL
+}
+
+func (r redirectTo) RoundTrip(req *http.Request) (*http.Response, error) {
+	out := req.Clone(req.Context())
+	out.URL.Scheme, out.URL.Host = r.target.Scheme, r.target.Host
+	out.Host = req.URL.Host
+	return http.DefaultTransport.RoundTrip(out)
+}
+
+func newTestStore(t *testing.T) *store.Store {
+	t.Helper()
+	ctx := context.Background()
+	st, err := store.Open(ctx, t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() {
+		if err := st.Close(); err != nil {
+			t.Error(err)
+		}
+	})
+	if err := store.Migrate(ctx, st.Writer, migrations.FS); err != nil {
+		t.Fatal(err)
+	}
+	return st
+}
+
+func newTestBox(t *testing.T) *secretbox.Box {
+	t.Helper()
+	key := make([]byte, secretbox.KeySize)
+	rand.Read(key)
+	box, err := secretbox.New(base64.StdEncoding.EncodeToString(key))
+	if err != nil {
+		t.Fatal(err)
+	}
+	return box
+}
+
+// newTestService returns a service over a migrated temp database whose
+// requests go to f, with cards linking under https://mealquest.example.
+func newTestService(t *testing.T, f *fakeChat) (*Service, *store.Store) {
+	t.Helper()
+	st := newTestStore(t)
+	target, err := url.Parse(f.srv.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	pub, err := url.Parse("https://mealquest.example")
+	if err != nil {
+		t.Fatal(err)
+	}
+	svc, err := NewService(st, newTestBox(t), pub, redirectTo{target})
+	if err != nil {
+		t.Fatal(err)
+	}
+	return svc, st
+}
+
+// assertNoSecret fails when s holds the webhook URL, its key or its token.
+func assertNoSecret(t *testing.T, what, s string) {
+	t.Helper()
+	tokenDecoded, _ := url.QueryUnescape(testToken)
+	for _, secret := range []string{testHook, testKey, testToken, tokenDecoded, testKey[:12], testToken[:12]} {
+		if strings.Contains(s, secret) {
+			t.Errorf("%s holds the webhook URL or a credential: %s", what, s)
+			return
+		}
+	}
+}
+
+func TestNewServiceRequiresDependencies(t *testing.T) {
+	t.Parallel()
+	st, box := newTestStore(t), newTestBox(t)
+	pub, _ := url.Parse("https://mealquest.example")
+	for name, build := range map[string]func() (*Service, error){
+		"store":      func() (*Service, error) { return NewService(nil, box, pub, http.DefaultTransport) },
+		"box":        func() (*Service, error) { return NewService(st, nil, pub, http.DefaultTransport) },
+		"public URL": func() (*Service, error) { return NewService(st, box, nil, http.DefaultTransport) },
+		"transport":  func() (*Service, error) { return NewService(st, box, pub, nil) },
+	} {
+		if _, err := build(); err == nil {
+			t.Errorf("NewService without %s succeeded", name)
+		}
+	}
+}
+
+func TestPutGetStoresSealedWebhook(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+	svc, st := newTestService(t, newFakeChat(t))
+
+	got, err := svc.Get(ctx)
+	if err != nil || got.Configured || got.SpaceLabel != nil || got.URLMasked != nil || got.LastTestAt != nil {
+		t.Fatalf("Get unconfigured = %+v, %v", got, err)
+	}
+
+	put, err := svc.Put(ctx, testHook, "  Family dinner  ")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !put.Configured || *put.SpaceLabel != "Family dinner" || *put.URLMasked != "https://chat.googleapis.com/v1/spaces/"+testSpace+"/messages?key=…&token=…ZxQ=" || put.LastTestAt != nil || put.LastTestStatus != nil {
+		t.Errorf("Put = %+v", put)
+	}
+	got, err = svc.Get(ctx)
+	if err != nil || *got.URLMasked != *put.URLMasked || *got.SpaceLabel != "Family dinner" {
+		t.Errorf("Get = %+v, %v", got, err)
+	}
+
+	row, err := db.New(st.Reader).GetChatSettings(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if bytes.Contains(row.WebhookUrlCt, []byte(testKey)) || bytes.Contains(row.WebhookUrlCt, []byte("chat.googleapis.com")) {
+		t.Errorf("webhook_url_ct holds the URL in plain text")
+	}
+	plain, err := svc.box.Decrypt(row.WebhookUrlCt)
+	if err != nil || string(plain) != testHook {
+		t.Errorf("webhook_url_ct decrypts to %q, %v", plain, err)
+	}
+	encoded, _ := json.Marshal(got)
+	assertNoSecret(t, "GET settings", string(encoded))
+}
+
+func TestPutRefusesInvalid(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+	svc, st := newTestService(t, newFakeChat(t))
+	for _, tc := range []struct {
+		url, label string
+		fields     []string
+	}{
+		{"https://chat.googleapis.com.evil.example/v1/spaces/X/messages?key=" + testKey + "&token=" + testToken, "Family", []string{"url"}},
+		{testHook, "   ", []string{"space_label"}},
+		{testHook, strings.Repeat("x", MaxSpaceLabelChars+1), []string{"space_label"}},
+		{testHook, "bad\nlabel", []string{"space_label"}},
+		{"http://chat.googleapis.com/v1/spaces/X/messages?key=" + testKey + "&token=" + testToken, "", []string{"url", "space_label"}},
+	} {
+		_, err := svc.Put(ctx, tc.url, tc.label)
+		var invalid *ValidationError
+		if !errors.As(err, &invalid) || len(invalid.Problems) != len(tc.fields) {
+			t.Errorf("Put(%q, %q) = %v, want problems with %v", tc.url, tc.label, err, tc.fields)
+			continue
+		}
+		for i, p := range invalid.Problems {
+			if p.Field != tc.fields[i] {
+				t.Errorf("Put(%q, %q) problem %d = %s, want %s", tc.url, tc.label, i, p.Field, tc.fields[i])
+			}
+		}
+		assertNoSecret(t, "validation error", err.Error())
+	}
+	if _, err := db.New(st.Reader).GetChatSettings(ctx); !errors.Is(err, sql.ErrNoRows) {
+		t.Errorf("a refused Put stored a row: %v", err)
+	}
+}
+
+func TestTestRecordsOutcome(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+	f := newFakeChat(t)
+	svc, _ := newTestService(t, f)
+	svc.now = func() time.Time { return time.Date(2026, 10, 9, 15, 0, 0, 0, time.UTC) }
+
+	if _, err := svc.Test(ctx); !errors.Is(err, ErrNotConfigured) {
+		t.Fatalf("Test unconfigured = %v, want ErrNotConfigured", err)
+	}
+	if _, err := svc.Put(ctx, testHook, "Family"); err != nil {
+		t.Fatal(err)
+	}
+
+	res, err := svc.Test(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.HTTPStatus != 200 || *res.LastTestStatus != TestOK || *res.LastTestAt != "2026-10-09T15:00:00.000Z" {
+		t.Errorf("Test = %+v, want 200 ok", res)
+	}
+	reqs := f.requests()
+	if len(reqs) != 1 {
+		t.Fatalf("Chat got %d requests, want 1", len(reqs))
+	}
+	r := reqs[0]
+	if r.Method != http.MethodPost || r.Host != "chat.googleapis.com" || r.Path != "/v1/spaces/"+testSpace+"/messages" ||
+		r.Query.Get("key") != testKey || r.Query.Get("threadKey") != "" || r.Body["text"] != TestText || r.Body["cardsV2"] != nil {
+		t.Errorf("test request = %+v", r)
+	}
+
+	f.setStatus(http.StatusNotFound)
+	res, err = svc.Test(ctx)
+	if err != nil || res.HTTPStatus != 404 || *res.LastTestStatus != TestFailed {
+		t.Errorf("Test answered 404 = %+v, %v; want 404 failed", res, err)
+	}
+	got, _ := svc.Get(ctx)
+	if *got.LastTestStatus != TestFailed || *got.LastTestAt != "2026-10-09T15:00:00.000Z" {
+		t.Errorf("Get after a failed test = %+v", got)
+	}
+
+	// A new webhook has no test outcome.
+	got, err = svc.Put(ctx, testHook, "Family")
+	if err != nil || got.LastTestAt != nil || got.LastTestStatus != nil {
+		t.Errorf("Put after a test = %+v, %v; want the outcome cleared", got, err)
+	}
+
+	f.srv.Close()
+	_, err = svc.Test(ctx)
+	if !errors.Is(err, ErrUnreachable) {
+		t.Errorf("Test against a stopped endpoint = %v, want ErrUnreachable", err)
+	} else {
+		assertNoSecret(t, "unreachable error", err.Error())
+	}
+	if got, _ := svc.Get(ctx); got.LastTestStatus == nil || *got.LastTestStatus != TestFailed {
+		t.Errorf("Get after an unanswered test = %+v, want failed", got)
+	}
+}
+
+func TestSendThreadsByWeek(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+	f := newFakeChat(t)
+	svc, _ := newTestService(t, f)
+	if _, err := svc.Put(ctx, testHook, "Family"); err != nil {
+		t.Fatal(err)
+	}
+	week := mustDate(t, "2026-10-12")
+	events := []notify.Event{
+		PlanReady(week, []string{"Tacos", "Bolognese", "Tikka masala", "A", "B", "C", "D"}),
+		ListReady(week, 19, 7),
+		DayOfReminder(mustDate(t, "2026-10-18"), "01J9DINNER", "Tacos"),
+		NewSuggestions("01J9BATCH", week, []string{"Pho"}),
+		RotationReview("01J9DINNER", "Pho", week),
+	}
+	for _, ev := range events {
+		if err := svc.Send(ctx, notify.Message{ID: "n1", EventKey: ev.Key, Channel: notify.ChannelChat, Payload: payloadOf(ev), Attempt: 1}); err != nil {
+			t.Fatalf("Send %s: %v", ev.Type, err)
+		}
+	}
+	reqs := f.requests()
+	if len(reqs) != len(events) {
+		t.Fatalf("Chat got %d requests, want %d", len(reqs), len(events))
+	}
+	for i, r := range reqs {
+		ev := events[i]
+		if r.Method != http.MethodPost || r.Path != "/v1/spaces/"+testSpace+"/messages" || !strings.HasPrefix(r.ContentType, "application/json") {
+			t.Errorf("%s: request = %+v", ev.Type, r)
+		}
+		if r.Query.Get("key") != testKey || r.Query.Get("token") != strings.ReplaceAll(testToken, "%3D", "=") {
+			t.Errorf("%s: key and token not kept: %v", ev.Type, r.Query)
+		}
+		if r.Query.Get("threadKey") != "mealquest-week-2026-W42" || r.Query.Get("messageReplyOption") != "REPLY_MESSAGE_FALLBACK_TO_NEW_THREAD" {
+			t.Errorf("%s: threading = %v", ev.Type, r.Query)
+		}
+		if want := Text(payloadOf(ev)); r.Body["text"] != want {
+			t.Errorf("%s: text = %q, want %q", ev.Type, r.Body["text"], want)
+		}
+		_, hasCards := r.Body["cardsV2"]
+		if hasCards != (ev.Type == notify.PlanReady || ev.Type == notify.ListReady) {
+			t.Errorf("%s: cardsV2 present = %v", ev.Type, hasCards)
+		}
+	}
+	if reqs[0].Body["text"] != "This week's plan is ready: Tacos, Bolognese, Tikka masala + 4 more. Open the plan →" {
+		t.Errorf("plan text = %q", reqs[0].Body["text"])
+	}
+
+	// The cards' "Open" buttons link under the public URL.
+	for i, wantLink := range map[int]string{0: "https://mealquest.example/plan", 1: "https://mealquest.example/plan/shopping"} {
+		data, _ := json.Marshal(reqs[i].Body["cardsV2"])
+		var cards []cardV2
+		if err := json.Unmarshal(data, &cards); err != nil || len(cards) != 1 {
+			t.Fatalf("cardsV2 = %s, %v", data, err)
+		}
+		c := cards[0]
+		buttons := c.Card.Sections[0].Widgets[0].ButtonList.Buttons
+		if c.CardID != string(events[i].Type) || c.Card.Header.Title != events[i].Title || c.Card.Header.Subtitle != events[i].Body ||
+			len(buttons) != 1 || buttons[0].Text != "Open" || buttons[0].OnClick.OpenLink.URL != wantLink {
+			t.Errorf("%s card = %s, want an Open button to %s", events[i].Type, data, wantLink)
+		}
+	}
+}
+
+func TestSendWithoutWeekIsUnthreaded(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+	f := newFakeChat(t)
+	svc, _ := newTestService(t, f)
+	if _, err := svc.Put(ctx, testHook, "Family"); err != nil {
+		t.Fatal(err)
+	}
+	p := notify.Payload{Event: notify.RotationReview, Title: "Keep it in rotation?", URL: "/", Tag: "rotation_review:x"}
+	if err := svc.Send(ctx, notify.Message{Payload: p}); err != nil {
+		t.Fatal(err)
+	}
+	if q := f.requests()[0].Query; q.Has("threadKey") || q.Has("messageReplyOption") {
+		t.Errorf("query = %v, want no threading", q)
+	}
+}
+
+func TestSendClassifiesStatus(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+	f := newFakeChat(t)
+	svc, _ := newTestService(t, f)
+	if _, err := svc.Put(ctx, testHook, "Family"); err != nil {
+		t.Fatal(err)
+	}
+	m := notify.Message{Payload: payloadOf(PlanReady(mustDate(t, "2026-10-12"), []string{"Tacos"}))}
+	for _, tc := range []struct {
+		status        int
+		ok, permanent bool
+	}{
+		{200, true, false},
+		{204, true, false},
+		{301, false, true},
+		{400, false, true},
+		{401, false, true},
+		{403, false, true},
+		{404, false, true},
+		{413, false, true},
+		{429, false, false},
+		{500, false, false},
+		{502, false, false},
+		{503, false, false},
+	} {
+		f.setStatus(tc.status)
+		err := svc.Send(ctx, m)
+		if (err == nil) != tc.ok || errors.Is(err, notify.ErrUndeliverable) != tc.permanent {
+			t.Errorf("status %d: Send = %v, want ok %v, undeliverable %v", tc.status, err, tc.ok, tc.permanent)
+		}
+		if err != nil {
+			assertNoSecret(t, "Send error", err.Error())
+		}
+	}
+
+	f.srv.Close()
+	err := svc.Send(ctx, m)
+	if err == nil || errors.Is(err, notify.ErrUndeliverable) {
+		t.Errorf("Send to a stopped endpoint = %v, want a retryable error", err)
+	} else {
+		assertNoSecret(t, "Send error", err.Error())
+	}
+}
+
+func TestSendWithoutWebhookIsUndeliverable(t *testing.T) {
+	t.Parallel()
+	svc, _ := newTestService(t, newFakeChat(t))
+	err := svc.Send(context.Background(), notify.Message{Payload: payloadOf(ListReady(mustDate(t, "2026-10-12"), 3, 2))})
+	if !errors.Is(err, notify.ErrUndeliverable) || !errors.Is(err, ErrNotConfigured) {
+		t.Errorf("Send = %v, want undeliverable, not configured", err)
+	}
+}
+
+// TestOutboxRowsFollowClassification delivers through the notify worker: a
+// 400 fails the row at once, a 503 leaves it pending for a retry. Neither
+// the stored error nor the log holds the webhook URL.
+func TestOutboxRowsFollowClassification(t *testing.T) {
+	t.Parallel()
+	ctx, cancel := context.WithCancel(context.Background())
+	f := newFakeChat(t)
+	svc, st := newTestService(t, f)
+	if _, err := svc.Put(ctx, testHook, "Family"); err != nil {
+		t.Fatal(err)
+	}
+	if err := household.SeedNotificationPrefs(ctx, st); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := st.Writer.Exec(`UPDATE notification_prefs SET push = 0, chat = 1`); err != nil {
+		t.Fatal(err)
+	}
+	var logs syncBuffer
+	notifier, err := notify.NewService(st, slog.New(slog.NewTextHandler(&logs, nil)))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := notifier.Register(notify.ChannelChat, svc); err != nil {
+		t.Fatal(err)
+	}
+	if err := notifier.Start(ctx); err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() {
+		cancel()
+		notifier.Wait()
+	})
+
+	week := mustDate(t, "2026-10-12")
+	f.setStatus(http.StatusBadRequest)
+	planned := PlanReady(week, []string{"Tacos"})
+	if err := notifier.Emit(ctx, planned); err != nil {
+		t.Fatal(err)
+	}
+	status, lastErr := waitForAttempt(t, st, planned.Key)
+	if status != "failed" || !strings.Contains(lastErr, "status 400") {
+		t.Errorf("row after a 400 = %s %q, want failed", status, lastErr)
+	}
+
+	f.setStatus(http.StatusServiceUnavailable)
+	listed := ListReady(week, 3, 1)
+	if err := notifier.Emit(ctx, listed); err != nil {
+		t.Fatal(err)
+	}
+	status, lastErr = waitForAttempt(t, st, listed.Key)
+	if status != "pending" || !strings.Contains(lastErr, "status 503") {
+		t.Errorf("row after a 503 = %s %q, want pending for a retry", status, lastErr)
+	}
+	cancel()
+	notifier.Wait()
+	assertNoSecret(t, "log", logs.String())
+	assertNoSecret(t, "last_error", lastErr)
+}
+
+// waitForAttempt waits for the chat row of key to have been attempted and
+// returns its status and last error.
+func waitForAttempt(t *testing.T, st *store.Store, key string) (string, string) {
+	t.Helper()
+	deadline := time.Now().Add(5 * time.Second)
+	for time.Now().Before(deadline) {
+		var status string
+		var attempts int
+		var lastErr sql.NullString
+		err := st.Reader.QueryRow(`SELECT status, attempts, last_error FROM notification_outbox WHERE event_key = ? AND channel = 'chat'`, key).
+			Scan(&status, &attempts, &lastErr)
+		if err != nil && !errors.Is(err, sql.ErrNoRows) {
+			t.Fatal(err)
+		}
+		if attempts > 0 {
+			return status, lastErr.String
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+	t.Fatalf("chat row of %s was never attempted", key)
+	return "", ""
+}
+
+// syncBuffer is a bytes.Buffer safe for the worker's logger.
+type syncBuffer struct {
+	mu  sync.Mutex
+	buf bytes.Buffer
+}
+
+func (b *syncBuffer) Write(p []byte) (int, error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return b.buf.Write(p)
+}
+
+func (b *syncBuffer) String() string {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return b.buf.String()
+}
diff --git a/internal/chat/messages.go b/internal/chat/messages.go
new file mode 100644
index 0000000..592a70d
--- /dev/null
+++ b/internal/chat/messages.go
@@ -0,0 +1,144 @@
+package chat
+
+import (
+	"fmt"
+	"strings"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/household"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/notify"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
+)
+
+// This file is the one place the notification texts are written. The
+// builders make the notify.Event of each event type, whose title and body
+// the push channel shows as they are; Text turns its payload into the Google
+// Chat message, such as "This week's plan is ready: Tacos, Bolognese,
+// Tikka masala + 4 more. Open the plan →".
+
+// TestText is the message POST /settings/chat-webhook/test sends.
+const TestText = "MealQuest · test message"
+
+// listedNames is how many names a message lists before "+ N more".
+const listedNames = 3
+
+// actions is the closing call to action of each event's Chat message.
+var actions = map[notify.EventType]string{
+	notify.PlanReady:      "Open the plan",
+	notify.ListReady:      "Open the Supply run",
+	notify.DayOfReminder:  "Open the recipe",
+	notify.NewSuggestions: "Open Discover",
+	notify.RotationReview: "Open MealQuest",
+}
+
+// carded are the events whose Chat message also has a card with an "Open"
+// button.
+var carded = map[notify.EventType]bool{notify.PlanReady: true, notify.ListReady: true}
+
+// PlanReady is the plan_ready event of the week starting on week, naming
+// its dinners in plan order.
+func PlanReady(week store.LocalDate, dinners []string) notify.Event {
+	return notify.Event{
+		Type:  notify.PlanReady,
+		Key:   string(notify.PlanReady) + ":" + week.String(),
+		Title: "This week's plan is ready",
+		Body:  nameList(dinners),
+		URL:   "/plan",
+		Week:  week,
+	}
+}
+
+// ListReady is the list_ready event of the Supply run of the week starting
+// on week: needed items to buy for its dinners.
+func ListReady(week store.LocalDate, needed, dinners int) notify.Event {
+	return notify.Event{
+		Type:  notify.ListReady,
+		Key:   string(notify.ListReady) + ":" + week.String(),
+		Title: "This week's Supply run is ready",
+		Body:  fmt.Sprintf("%s to buy for %s", count(needed, "item", "items"), count(dinners, "dinner", "dinners")),
+		URL:   "/plan/shopping",
+		Week:  week,
+	}
+}
+
+// DayOfReminder is the day_of_reminder event of the dinner dinnerID, named
+// name, planned on date.
+func DayOfReminder(date store.LocalDate, dinnerID, name string) notify.Event {
+	return notify.Event{
+		Type:  notify.DayOfReminder,
+		Key:   string(notify.DayOfReminder) + ":" + date.String(),
+		Title: "Tonight's dinner",
+		Body:  name,
+		URL:   "/dinner/" + dinnerID,
+		Week:  household.WeekStart(date),
+	}
+}
+
+// NewSuggestions is the new_suggestions event of suggestion batch batchID,
+// made in the week starting on week, naming its Side quests.
+func NewSuggestions(batchID string, week store.LocalDate, names []string) notify.Event {
+	return notify.Event{
+		Type:  notify.NewSuggestions,
+		Key:   string(notify.NewSuggestions) + ":" + batchID,
+		Title: "New Side quests are in",
+		Body:  nameList(names),
+		URL:   "/discover",
+		Week:  week,
+	}
+}
+
+// RotationReview is the rotation_review event asking whether the dinner
+// dinnerID, named name and tried in the week starting on week, becomes a
+// Regular.
+func RotationReview(dinnerID, name string, week store.LocalDate) notify.Event {
+	return notify.Event{
+		Type:  notify.RotationReview,
+		Key:   string(notify.RotationReview) + ":" + dinnerID,
+		Title: "Keep it in rotation?",
+		Body:  "You tried " + name + ". Make it a Regular?",
+		URL:   "/",
+		Week:  week,
+	}
+}
+
+// Text is the Google Chat message of p: its title, its body after a colon
+// and the event's call to action with an arrow.
+func Text(p notify.Payload) string {
+	text := p.Title
+	if p.Body != "" {
+		if endsSentence(text) {
+			text += " "
+		} else {
+			text += ": "
+		}
+		text += p.Body
+	}
+	if !endsSentence(text) {
+		text += "."
+	}
+	if action, ok := actions[p.Event]; ok {
+		text += " " + action + " →"
+	}
+	return text
+}
+
+// endsSentence reports whether s ends with sentence punctuation.
+func endsSentence(s string) bool {
+	return strings.HasSuffix(s, ".") || strings.HasSuffix(s, "?") || strings.HasSuffix(s, "!")
+}
+
+// nameList lists the first listedNames of names, then how many more there
+// are: "Tacos, Bolognese, Tikka masala + 4 more".
+func nameList(names []string) string {
+	if len(names) <= listedNames {
+		return strings.Join(names, ", ")
+	}
+	return fmt.Sprintf("%s + %d more", strings.Join(names[:listedNames], ", "), len(names)-listedNames)
+}
+
+// count is n with the singular or plural noun.
+func count(n int, one, many string) string {
+	if n == 1 {
+		return "1 " + one
+	}
+	return fmt.Sprintf("%d %s", n, many)
+}
diff --git a/internal/chat/messages_test.go b/internal/chat/messages_test.go
new file mode 100644
index 0000000..4386606
--- /dev/null
+++ b/internal/chat/messages_test.go
@@ -0,0 +1,137 @@
+package chat
+
+import (
+	"testing"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/notify"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
+)
+
+func mustDate(t *testing.T, s string) store.LocalDate {
+	t.Helper()
+	d, err := store.ParseLocalDate(s)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return d
+}
+
+// payloadOf is the payload notify stores for ev.
+func payloadOf(ev notify.Event) notify.Payload {
+	p := notify.Payload{Event: ev.Type, Title: ev.Title, Body: ev.Body, URL: ev.URL, Tag: ev.Key}
+	if !ev.Week.IsZero() {
+		p.Week = ev.Week.String()
+	}
+	return p
+}
+
+func TestMessages(t *testing.T) {
+	t.Parallel()
+	week := mustDate(t, "2026-10-12")
+	for _, tc := range []struct {
+		name               string
+		ev                 notify.Event
+		key, url, week     string
+		title, body, chatT string
+	}{
+		{
+			name:  "plan ready",
+			ev:    PlanReady(week, []string{"Tacos", "Bolognese", "Tikka masala", "Lemon orzo", "Bibimbap", "Shakshuka", "Chili"}),
+			key:   "plan_ready:2026-10-12",
+			url:   "/plan",
+			week:  "2026-10-12",
+			title: "This week's plan is ready",
+			body:  "Tacos, Bolognese, Tikka masala + 4 more",
+			chatT: "This week's plan is ready: Tacos, Bolognese, Tikka masala + 4 more. Open the plan →",
+		},
+		{
+			name:  "plan ready with three dinners",
+			ev:    PlanReady(week, []string{"Tacos", "Bolognese", "Tikka masala"}),
+			key:   "plan_ready:2026-10-12",
+			url:   "/plan",
+			week:  "2026-10-12",
+			title: "This week's plan is ready",
+			body:  "Tacos, Bolognese, Tikka masala",
+			chatT: "This week's plan is ready: Tacos, Bolognese, Tikka masala. Open the plan →",
+		},
+		{
+			name:  "list ready",
+			ev:    ListReady(week, 19, 7),
+			key:   "list_ready:2026-10-12",
+			url:   "/plan/shopping",
+			week:  "2026-10-12",
+			title: "This week's Supply run is ready",
+			body:  "19 items to buy for 7 dinners",
+			chatT: "This week's Supply run is ready: 19 items to buy for 7 dinners. Open the Supply run →",
+		},
+		{
+			name:  "list ready singular",
+			ev:    ListReady(week, 1, 1),
+			key:   "list_ready:2026-10-12",
+			url:   "/plan/shopping",
+			week:  "2026-10-12",
+			title: "This week's Supply run is ready",
+			body:  "1 item to buy for 1 dinner",
+			chatT: "This week's Supply run is ready: 1 item to buy for 1 dinner. Open the Supply run →",
+		},
+		{
+			name:  "day-of reminder",
+			ev:    DayOfReminder(mustDate(t, "2026-10-15"), "01J9Z8Y7X6W5V4T3S2R1Q0P9N8", "Tacos"),
+			key:   "day_of_reminder:2026-10-15",
+			url:   "/dinner/01J9Z8Y7X6W5V4T3S2R1Q0P9N8",
+			week:  "2026-10-12",
+			title: "Tonight's dinner",
+			body:  "Tacos",
+			chatT: "Tonight's dinner: Tacos. Open the recipe →",
+		},
+		{
+			name:  "new suggestions",
+			ev:    NewSuggestions("01J9BATCH", week, []string{"Lemon orzo", "Bibimbap", "Shakshuka", "Pho", "Paella"}),
+			key:   "new_suggestions:01J9BATCH",
+			url:   "/discover",
+			week:  "2026-10-12",
+			title: "New Side quests are in",
+			body:  "Lemon orzo, Bibimbap, Shakshuka + 2 more",
+			chatT: "New Side quests are in: Lemon orzo, Bibimbap, Shakshuka + 2 more. Open Discover →",
+		},
+		{
+			name:  "rotation review",
+			ev:    RotationReview("01J9DINNER", "Lemon orzo", week),
+			key:   "rotation_review:01J9DINNER",
+			url:   "/",
+			week:  "2026-10-12",
+			title: "Keep it in rotation?",
+			body:  "You tried Lemon orzo. Make it a Regular?",
+			chatT: "Keep it in rotation? You tried Lemon orzo. Make it a Regular? Open MealQuest →",
+		},
+	} {
+		ev := tc.ev
+		if ev.Key != tc.key || ev.URL != tc.url || ev.Week.String() != tc.week || ev.Title != tc.title || ev.Body != tc.body {
+			t.Errorf("%s: event = %+v, want key %q url %q week %s title %q body %q", tc.name, ev, tc.key, tc.url, tc.week, tc.title, tc.body)
+		}
+		if got := Text(payloadOf(ev)); got != tc.chatT {
+			t.Errorf("%s: Text = %q, want %q", tc.name, got, tc.chatT)
+		}
+	}
+}
+
+func TestTextWithoutBody(t *testing.T) {
+	t.Parallel()
+	got := Text(notify.Payload{Event: notify.PlanReady, Title: "This week's plan is ready", URL: "/plan"})
+	if want := "This week's plan is ready. Open the plan →"; got != want {
+		t.Errorf("Text = %q, want %q", got, want)
+	}
+}
+
+func TestThreadKey(t *testing.T) {
+	t.Parallel()
+	for date, want := range map[string]string{
+		"2026-10-12": "mealquest-week-2026-W42",
+		"2026-12-28": "mealquest-week-2026-W53",
+		"2027-01-04": "mealquest-week-2027-W01",
+	} {
+		if got := ThreadKey(mustDate(t, date)); got != want {
+			t.Errorf("ThreadKey(%s) = %q, want %q", date, got, want)
+		}
+	}
+}
diff --git a/internal/chat/webhook.go b/internal/chat/webhook.go
new file mode 100644
index 0000000..f42ae91
--- /dev/null
+++ b/internal/chat/webhook.go
@@ -0,0 +1,104 @@
+package chat
+
+import (
+	"errors"
+	"fmt"
+	"net/url"
+	"regexp"
+	"strings"
+)
+
+const (
+	// webhookPrefix is how every accepted webhook URL starts, compared
+	// exactly: no other scheme, host spelling, port or user info.
+	webhookPrefix = "https://chat.googleapis.com/v1/spaces/"
+	// webhookHost is the only host a webhook URL may name.
+	webhookHost = "chat.googleapis.com"
+	// MaxWebhookURLLength bounds an accepted webhook URL.
+	MaxWebhookURLLength = 2048
+	// MinCredentialLength is the shortest key or token accepted, so the
+	// masked URL's token tail never gives away most of it.
+	MinCredentialLength = 16
+	// maskedTail is how many trailing characters of the token the masked
+	// URL shows.
+	maskedTail = 4
+)
+
+// webhookPath is the path of a space's incoming webhook; the group is the
+// space id.
+var webhookPath = regexp.MustCompile(`^/v1/spaces/([A-Za-z0-9_-]{1,128})/messages$`)
+
+// Webhook is a validated Google Chat incoming webhook URL. Its String is
+// the full URL, a secret: it is only ever sealed for storage or sent to
+// Google Chat, never logged, shown or put in an error.
+type Webhook struct {
+	raw   string
+	space string
+	token string
+}
+
+// ParseWebhook validates raw as
+// https://chat.googleapis.com/v1/spaces/{space}/messages?key=…&token=…,
+// with exactly the query parameters key and token, each once and at least
+// MinCredentialLength characters. Its error never quotes raw.
+func ParseWebhook(raw string) (Webhook, error) {
+	switch {
+	case raw == "":
+		return Webhook{}, errors.New("is required")
+	case len(raw) > MaxWebhookURLLength:
+		return Webhook{}, fmt.Errorf("must be at most %d characters", MaxWebhookURLLength)
+	case strings.ContainsFunc(raw, func(r rune) bool { return r <= ' ' || r == 0x7f }):
+		return Webhook{}, errors.New("must not contain spaces or control characters")
+	case !strings.HasPrefix(raw, webhookPrefix):
+		return Webhook{}, errors.New("must be a Google Chat incoming webhook URL starting with " + webhookPrefix)
+	case strings.Contains(raw, "#"):
+		return Webhook{}, errors.New("must not have a fragment")
+	}
+	u, err := url.Parse(raw)
+	if err != nil {
+		return Webhook{}, errors.New("is not a valid URL")
+	}
+	if u.Scheme != "https" || u.Host != webhookHost || u.User != nil || u.Opaque != "" || u.RawPath != "" {
+		return Webhook{}, errors.New("must be a Google Chat incoming webhook URL starting with " + webhookPrefix)
+	}
+	m := webhookPath.FindStringSubmatch(u.Path)
+	if m == nil {
+		return Webhook{}, errors.New("path must be /v1/spaces/{space}/messages")
+	}
+	q, err := url.ParseQuery(u.RawQuery)
+	if err != nil {
+		return Webhook{}, errors.New("query is not valid")
+	}
+	for name, values := range q {
+		if name != "key" && name != "token" {
+			return Webhook{}, errors.New("query must hold only key and token")
+		}
+		if len(values) != 1 {
+			return Webhook{}, fmt.Errorf("query must hold %s once", name)
+		}
+	}
+	for _, name := range []string{"key", "token"} {
+		v := q.Get(name)
+		if v == "" {
+			return Webhook{}, fmt.Errorf("query must hold a %s", name)
+		}
+		if len(v) < MinCredentialLength {
+			return Webhook{}, fmt.Errorf("%s must be at least %d characters", name, MinCredentialLength)
+		}
+	}
+	return Webhook{raw: raw, space: m[1], token: q.Get("token")}, nil
+}
+
+// String returns the full webhook URL, a secret.
+func (w Webhook) String() string {
+	return w.raw
+}
+
+// Masked returns the URL with its key hidden and only the last few
+// characters of its token, such as
+// "https://chat.googleapis.com/v1/spaces/AAQA1234/messages?key=…&token=…x3Dk".
+func (w Webhook) Masked() string {
+	// MinCredentialLength bytes are at least maskedTail runes.
+	token := []rune(w.token)
+	return webhookPrefix + w.space + "/messages?key=…&token=…" + string(token[len(token)-maskedTail:])
+}
diff --git a/internal/chat/webhook_test.go b/internal/chat/webhook_test.go
new file mode 100644
index 0000000..c5c4e96
--- /dev/null
+++ b/internal/chat/webhook_test.go
@@ -0,0 +1,94 @@
+package chat
+
+import (
+	"strings"
+	"testing"
+)
+
+const (
+	testKey   = "AIzaSyDdI0hCZtE6vySjMm-WEfRq3CPzqKqqsHI"
+	testToken = "q0Lz3kV9Yw8pXcRtN2bHsJdFgA7uEmKiOlP1nZxQ%3D"
+	testSpace = "AAQA1b2C3d4"
+	testHook  = "https://chat.googleapis.com/v1/spaces/" + testSpace + "/messages?key=" + testKey + "&token=" + testToken
+)
+
+func TestParseWebhookAccepts(t *testing.T) {
+	t.Parallel()
+	for _, raw := range []string{
+		testHook,
+		"https://chat.googleapis.com/v1/spaces/" + testSpace + "/messages?token=" + testToken + "&key=" + testKey,
+		"https://chat.googleapis.com/v1/spaces/AAAA_x-y/messages?key=" + testKey + "&token=" + testToken,
+	} {
+		hook, err := ParseWebhook(raw)
+		if err != nil {
+			t.Errorf("ParseWebhook(%q) = %v, want accepted", raw, err)
+			continue
+		}
+		if hook.String() != raw {
+			t.Errorf("String() = %q, want %q", hook.String(), raw)
+		}
+	}
+}
+
+func TestParseWebhookRejects(t *testing.T) {
+	t.Parallel()
+	q := "?key=" + testKey + "&token=" + testToken
+	for name, raw := range map[string]string{
+		"empty":               "",
+		"http":                "http://chat.googleapis.com/v1/spaces/" + testSpace + "/messages" + q,
+		"upper-case scheme":   "HTTPS://chat.googleapis.com/v1/spaces/" + testSpace + "/messages" + q,
+		"lookalike suffix":    "https://chat.googleapis.com.evil.example/v1/spaces/" + testSpace + "/messages" + q,
+		"lookalike prefix":    "https://evilchat.googleapis.com/v1/spaces/" + testSpace + "/messages" + q,
+		"other google host":   "https://www.googleapis.com/v1/spaces/" + testSpace + "/messages" + q,
+		"upper-case host":     "https://CHAT.googleapis.com/v1/spaces/" + testSpace + "/messages" + q,
+		"port":                "https://chat.googleapis.com:443/v1/spaces/" + testSpace + "/messages" + q,
+		"user info":           "https://user@chat.googleapis.com/v1/spaces/" + testSpace + "/messages" + q,
+		"trailing dot host":   "https://chat.googleapis.com./v1/spaces/" + testSpace + "/messages" + q,
+		"no space":            "https://chat.googleapis.com/v1/spaces//messages" + q,
+		"extra path":          "https://chat.googleapis.com/v1/spaces/" + testSpace + "/messages/x" + q,
+		"other version":       "https://chat.googleapis.com/v2/spaces/" + testSpace + "/messages" + q,
+		"members path":        "https://chat.googleapis.com/v1/spaces/" + testSpace + "/members" + q,
+		"escaped path":        "https://chat.googleapis.com/v1/spaces/AA%2FQA/messages" + q,
+		"dot segment":         "https://chat.googleapis.com/v1/spaces/../messages" + q,
+		"no query":            "https://chat.googleapis.com/v1/spaces/" + testSpace + "/messages",
+		"no key":              "https://chat.googleapis.com/v1/spaces/" + testSpace + "/messages?token=" + testToken,
+		"no token":            "https://chat.googleapis.com/v1/spaces/" + testSpace + "/messages?key=" + testKey,
+		"empty token":         "https://chat.googleapis.com/v1/spaces/" + testSpace + "/messages?key=" + testKey + "&token=",
+		"short key":           "https://chat.googleapis.com/v1/spaces/" + testSpace + "/messages?key=abc&token=" + testToken,
+		"repeated key":        "https://chat.googleapis.com/v1/spaces/" + testSpace + "/messages" + q + "&key=" + testKey,
+		"extra parameter":     "https://chat.googleapis.com/v1/spaces/" + testSpace + "/messages" + q + "&threadKey=x",
+		"bad escape in query": "https://chat.googleapis.com/v1/spaces/" + testSpace + "/messages" + q + "%zz",
+		"fragment":            testHook + "#frag",
+		"space":               testHook + " ",
+		"newline":             testHook + "\n",
+		"too long":            testHook + strings.Repeat("A", MaxWebhookURLLength),
+		"not a URL":           "chat webhook please",
+	} {
+		_, err := ParseWebhook(raw)
+		if err == nil {
+			t.Errorf("%s: ParseWebhook(%q) accepted", name, raw)
+			continue
+		}
+		for _, secret := range []string{testKey, testToken, testSpace} {
+			if strings.Contains(err.Error(), secret) {
+				t.Errorf("%s: error %q quotes the URL", name, err)
+			}
+		}
+	}
+}
+
+func TestWebhookMasked(t *testing.T) {
+	t.Parallel()
+	hook, err := ParseWebhook(testHook)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// The tail is of the token as it decodes: "%3D" is "=".
+	want := "https://chat.googleapis.com/v1/spaces/" + testSpace + "/messages?key=…&token=…ZxQ="
+	if got := hook.Masked(); got != want {
+		t.Errorf("Masked() = %q, want %q", got, want)
+	}
+	if m := hook.Masked(); strings.Contains(m, testKey) || strings.Contains(m, testToken) || strings.Contains(m, testToken[:8]) {
+		t.Errorf("Masked() = %q holds the key or token", m)
+	}
+}
diff --git a/internal/db/querier.go b/internal/db/querier.go
index 1a1f6cd..8d3e14c 100644
--- a/internal/db/querier.go
+++ b/internal/db/querier.go
@@ -260,6 +260,10 @@ type Querier interface {
 	// event id while its dinner stays the same; a new dinner clears it, since
 	// Calendar no longer shows the day as planned.
 	PutPlanDay(ctx context.Context, arg PutPlanDayParams) error
+	// Records the outcome of a test message sent to the webhook sealed in
+	// webhook_url_ct; affects no row when the webhook has been replaced or
+	// removed since the test began.
+	RecordChatTest(ctx context.Context, arg RecordChatTestParams) (int64, error)
 	// Counts a delivery to a subscription that the push service did not accept.
 	RecordPushFailure(ctx context.Context, id string) error
 	// Records that the push service accepted a notification for a subscription.
diff --git a/internal/db/settings.sql.go b/internal/db/settings.sql.go
index a68719b..04e9ec7 100644
--- a/internal/db/settings.sql.go
+++ b/internal/db/settings.sql.go
@@ -161,6 +161,35 @@ func (q *Queries) GetRecipeSearchSettings(ctx context.Context) (RecipeSearchSett
 	return i, err
 }
 
+const recordChatTest = `-- name: RecordChatTest :execrows
+UPDATE chat_settings
+SET last_test_at = ?, last_test_status = ?, updated_at = ?
+WHERE id = 1 AND webhook_url_ct = ?
+`
+
+type RecordChatTestParams struct {
+	LastTestAt     sql.NullString
+	LastTestStatus sql.NullString
+	UpdatedAt      string
+	WebhookUrlCt   []byte
+}
+
+// Records the outcome of a test message sent to the webhook sealed in
+// webhook_url_ct; affects no row when the webhook has been replaced or
+// removed since the test began.
+func (q *Queries) RecordChatTest(ctx context.Context, arg RecordChatTestParams) (int64, error) {
+	result, err := q.db.ExecContext(ctx, recordChatTest,
+		arg.LastTestAt,
+		arg.LastTestStatus,
+		arg.UpdatedAt,
+		arg.WebhookUrlCt,
+	)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected()
+}
+
 const setIntegrationsGoogleCalendar = `-- name: SetIntegrationsGoogleCalendar :execrows
 UPDATE integrations_google
 SET calendar_id = ?, calendar_name = ?, updated_at = ?
diff --git a/internal/notify/notify.go b/internal/notify/notify.go
index 92a5906..31017b5 100644
--- a/internal/notify/notify.go
+++ b/internal/notify/notify.go
@@ -12,7 +12,8 @@
 // registered for their channel. A delivered row is marked sent. A failed
 // delivery is retried after a backoff of one minute doubling up to one hour,
 // until 24 hours after the row was created; the delivery that fails at or
-// after that point marks it failed, with the error in last_error.
+// after that point, or with an error wrapping ErrUndeliverable, marks it
+// failed, with the error in last_error.
 package notify
 
 import (
diff --git a/internal/notify/notify_test.go b/internal/notify/notify_test.go
index 16b3470..cb124e5 100644
--- a/internal/notify/notify_test.go
+++ b/internal/notify/notify_test.go
@@ -422,6 +422,31 @@ func TestRetryThenSent(t *testing.T) {
 	}
 }
 
+func TestUndeliverableFailsAtOnce(t *testing.T) {
+	ctx := context.Background()
+	svc, st, _ := newTestService(t)
+	setPref(t, st, PlanReady, false, true)
+	sender := &fakeSender{fail: fmt.Errorf("%w: chat refused the message (status 400)", ErrUndeliverable)}
+	if err := svc.Register(ChannelChat, sender); err != nil {
+		t.Fatal(err)
+	}
+	const key = "plan_ready:2026-10-12"
+	if err := svc.Emit(ctx, planReady(key)); err != nil {
+		t.Fatal(err)
+	}
+	wait, err := svc.deliverDue(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	r := onlyRow(t, st, key, ChannelChat)
+	if r.Status != "failed" || r.Attempts != 1 || r.LastError.String != sender.fail.Error() {
+		t.Fatalf("row = %+v, want failed after one attempt with the sender's error", r)
+	}
+	if wait != -1 || len(sender.messages()) != 1 {
+		t.Fatalf("wait = %v after %d deliveries, want nothing pending after one", wait, len(sender.messages()))
+	}
+}
+
 func TestGiveUpAfter24Hours(t *testing.T) {
 	ctx := context.Background()
 	svc, st, c := newTestService(t)
diff --git a/internal/notify/worker.go b/internal/notify/worker.go
index 796e7c2..c188556 100644
--- a/internal/notify/worker.go
+++ b/internal/notify/worker.go
@@ -48,8 +48,14 @@ type Message struct {
 	Attempt int64
 }
 
+// ErrUndeliverable is wrapped by a Sender's error when retrying cannot
+// help, such as a channel refusing the message outright: the worker marks
+// the row failed at once instead of retrying it.
+var ErrUndeliverable = errors.New("notify: undeliverable")
+
 // Sender delivers notifications on one channel. Send returns nil once the
-// channel has accepted m, and an error otherwise; the worker retries it.
+// channel has accepted m, and an error otherwise; the worker retries it,
+// unless the error wraps ErrUndeliverable.
 // The error's text is stored in notification_outbox.last_error and logged,
 // so it must never carry a secret: no webhook URL, key or token (a
 // *url.Error quotes its URL).
@@ -235,7 +241,7 @@ func (s *Service) deliver(ctx context.Context, row db.NotificationOutbox) {
 		return
 	}
 
-	if !now.Before(deadline) {
+	if errors.Is(err, ErrUndeliverable) || !now.Before(deadline) {
 		logger.ErrorContext(ctx, "notification failed; giving up", "attempt", attempt, "error", err)
 		s.giveUp(ctx, logger, row, 1, err.Error())
 		return
diff --git a/internal/server/aisettings_test.go b/internal/server/aisettings_test.go
index 18a3a2a..9dcd118 100644
--- a/internal/server/aisettings_test.go
+++ b/internal/server/aisettings_test.go
@@ -28,7 +28,7 @@ const (
 func newAIRouter(t *testing.T) http.Handler {
 	t.Helper()
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	r, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t),
+	r, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t),
 		newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)
diff --git a/internal/server/chat.go b/internal/server/chat.go
new file mode 100644
index 0000000..75a735d
--- /dev/null
+++ b/internal/server/chat.go
@@ -0,0 +1,84 @@
+package server
+
+import (
+	"errors"
+	"log/slog"
+	"net/http"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/chat"
+)
+
+// chatWebhookBody is the PUT /settings/chat-webhook body. Both fields are
+// required.
+type chatWebhookBody struct {
+	URL        *string `json:"url"`
+	SpaceLabel *string `json:"space_label"`
+}
+
+// getChatWebhook answers the stored webhook's settings, which never hold
+// its URL.
+func getChatWebhook(logger *slog.Logger, svc *chat.Service) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		settings, err := svc.Get(r.Context())
+		if err != nil {
+			logger.ErrorContext(r.Context(), "get chat webhook", "error", err)
+			writeError(w, r, logger, http.StatusInternalServerError, "internal", "internal error")
+			return
+		}
+		writeJSON(w, r, logger, http.StatusOK, settings)
+	}
+}
+
+// putChatWebhook stores the webhook URL sealed, with its space label, and
+// answers the settings as GET does.
+func putChatWebhook(logger *slog.Logger, svc *chat.Service) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		body, err := decodePatch[chatWebhookBody](http.MaxBytesReader(w, r.Body, maxSettingsBody))
+		if err != nil {
+			writeError(w, r, logger, http.StatusBadRequest, "invalid_request", err.Error())
+			return
+		}
+		if body.URL == nil || body.SpaceLabel == nil {
+			writeError(w, r, logger, http.StatusBadRequest, "invalid_request", "url and space_label are required")
+			return
+		}
+		settings, err := svc.Put(r.Context(), *body.URL, *body.SpaceLabel)
+		var invalid *chat.ValidationError
+		if errors.As(err, &invalid) {
+			writeError(w, r, logger, http.StatusBadRequest, "invalid_webhook", invalid.Error())
+			return
+		}
+		if err != nil {
+			logger.ErrorContext(r.Context(), "save chat webhook", "error", err)
+			writeError(w, r, logger, http.StatusInternalServerError, "internal", "internal error")
+			return
+		}
+		writeJSON(w, r, logger, http.StatusOK, settings)
+	}
+}
+
+// postChatWebhookTest sends chat.TestText to the stored webhook and answers
+// 200 with the status Google Chat answered, whatever it was, and the
+// recorded outcome. No webhook stored, or one replaced during the test, is
+// 409; no answer from Google Chat is 502.
+func postChatWebhookTest(logger *slog.Logger, svc *chat.Service) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		result, err := svc.Test(r.Context())
+		switch {
+		case errors.Is(err, chat.ErrNotConfigured):
+			writeError(w, r, logger, http.StatusConflict, "not_configured", "no Google Chat webhook is configured")
+		case errors.Is(err, chat.ErrWebhookChanged):
+			writeError(w, r, logger, http.StatusConflict, "webhook_changed", "the Google Chat webhook changed during the test; test it again")
+		case err != nil && r.Context().Err() != nil:
+			logger.WarnContext(r.Context(), "chat webhook test interrupted", "error", err)
+		case errors.Is(err, chat.ErrUnreachable):
+			logger.WarnContext(r.Context(), "chat webhook test failed", "error", err)
+			writeError(w, r, logger, http.StatusBadGateway, "chat_unreachable", "Google Chat did not answer the test message")
+		case err != nil:
+			logger.ErrorContext(r.Context(), "chat webhook test", "error", err)
+			writeError(w, r, logger, http.StatusInternalServerError, "internal", "internal error")
+		default:
+			writeJSON(w, r, logger, http.StatusOK, result)
+		}
+	}
+}
diff --git a/internal/server/chat_test.go b/internal/server/chat_test.go
new file mode 100644
index 0000000..14ca2c6
--- /dev/null
+++ b/internal/server/chat_test.go
@@ -0,0 +1,239 @@
+package server
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"sync"
+	"testing"
+	"testing/fstest"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/chat"
+)
+
+const (
+	chatWebhookPath     = "/api/v1/settings/chat-webhook"
+	chatWebhookTestPath = "/api/v1/settings/chat-webhook/test"
+	testChatKey         = "AIzaSyDdI0hCZtE6vySjMm-WEfRq3CPzqKqqsHI"
+	testChatToken       = "q0Lz3kV9Yw8pXcRtN2bHsJdFgA7uEmKiOlP1nZxQ%3D"
+	testChatHook        = "https://chat.googleapis.com/v1/spaces/AAQA1b2C3d4/messages?key=" + testChatKey + "&token=" + testChatToken
+)
+
+// refuseTransport fails every request, as a Chat endpoint that is down.
+type refuseTransport struct{}
+
+func (refuseTransport) RoundTrip(*http.Request) (*http.Response, error) {
+	return nil, errors.New("connection refused")
+}
+
+// chatTransport sends every request to the server at target, as if it
+// were chat.googleapis.com.
+type chatTransport struct {
+	target *url.URL
+}
+
+func (c chatTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	out := req.Clone(req.Context())
+	out.URL.Scheme, out.URL.Host = c.target.Scheme, c.target.Host
+	return http.DefaultTransport.RoundTrip(out)
+}
+
+// newTestChat returns a Google Chat service over a migrated temp database
+// whose requests all fail.
+func newTestChat(t *testing.T) *chat.Service {
+	t.Helper()
+	return newTestChatVia(t, refuseTransport{})
+}
+
+func newTestChatVia(t *testing.T, transport http.RoundTripper) *chat.Service {
+	t.Helper()
+	pub, err := url.Parse("https://mealquest.example")
+	if err != nil {
+		t.Fatal(err)
+	}
+	svc, err := chat.NewService(newTestStore(t), newTestBox(t), pub, transport)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return svc
+}
+
+// lockedBuffer is a bytes.Buffer safe for a logger.
+type lockedBuffer struct {
+	mu  sync.Mutex
+	buf bytes.Buffer
+}
+
+func (b *lockedBuffer) Write(p []byte) (int, error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return b.buf.Write(p)
+}
+
+func (b *lockedBuffer) String() string {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return b.buf.String()
+}
+
+// newChatRouter returns a router serving svc, logging at debug level to
+// logs.
+func newChatRouter(t *testing.T, svc *chat.Service, logs io.Writer) http.Handler {
+	t.Helper()
+	logger := slog.New(slog.NewTextHandler(logs, &slog.HandlerOptions{Level: slog.LevelDebug}))
+	r, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), svc, newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t),
+		newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	return r
+}
+
+func TestChatWebhookAPI(t *testing.T) {
+	t.Parallel()
+	var (
+		mu       sync.Mutex
+		status   = http.StatusOK
+		received []string
+	)
+	chatSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		body, _ := io.ReadAll(r.Body)
+		mu.Lock()
+		defer mu.Unlock()
+		received = append(received, string(body))
+		w.WriteHeader(status)
+	}))
+	t.Cleanup(chatSrv.Close)
+	target, _ := url.Parse(chatSrv.URL)
+	setStatus := func(s int) {
+		mu.Lock()
+		defer mu.Unlock()
+		status = s
+	}
+
+	var logs lockedBuffer
+	router := newChatRouter(t, newTestChatVia(t, chatTransport{target}), &logs)
+	var bodies []string
+	call := func(method, target, body string) (*httptest.ResponseRecorder, map[string]any) {
+		t.Helper()
+		var r io.Reader
+		if body != "" {
+			r = strings.NewReader(body)
+		}
+		rec, decoded := serve(t, router, signedIn(method, target, r))
+		bodies = append(bodies, rec.Body.String())
+		return rec, decoded
+	}
+
+	rec, body := call(http.MethodGet, chatWebhookPath, "")
+	if rec.Code != http.StatusOK || body["configured"] != false || body["url_masked"] != nil || body["space_label"] != nil {
+		t.Errorf("GET unconfigured = %d %v", rec.Code, body)
+	}
+	rec, body = call(http.MethodPost, chatWebhookTestPath, "")
+	if rec.Code != http.StatusConflict || body["error"].(map[string]any)["code"] != "not_configured" {
+		t.Errorf("POST test unconfigured = %d %v", rec.Code, body)
+	}
+
+	q := "?key=" + testChatKey + "&token=" + testChatToken
+	for _, bad := range []struct{ body, code string }{
+		{`{"url":"https://chat.googleapis.com.evil.example/v1/spaces/X/messages` + q + `","space_label":"Family"}`, "invalid_webhook"},
+		{`{"url":"http://chat.googleapis.com/v1/spaces/X/messages` + q + `","space_label":"Family"}`, "invalid_webhook"},
+		{`{"url":"https://chat.googleapis.com/v1/spaces/X/messages?key=` + testChatKey + `","space_label":"Family"}`, "invalid_webhook"},
+		{`{"url":"https://chat.googleapis.com/v1/spaces/X/threads` + q + `","space_label":"Family"}`, "invalid_webhook"},
+		{`{"url":"` + testChatHook + `","space_label":""}`, "invalid_webhook"},
+		{`{"url":"` + testChatHook + `"}`, "invalid_request"},
+		{`{"space_label":"Family"}`, "invalid_request"},
+		{`{"url":"` + testChatHook + `","space_label":null}`, "invalid_request"},
+		{`{"url":"` + testChatHook + `","space_label":"Family","extra":1}`, "invalid_request"},
+		{`not json`, "invalid_request"},
+	} {
+		rec, body := call(http.MethodPut, chatWebhookPath, bad.body)
+		if rec.Code != http.StatusBadRequest || body["error"].(map[string]any)["code"] != bad.code {
+			t.Errorf("PUT %s = %d %v, want 400 %s", bad.body, rec.Code, body, bad.code)
+		}
+	}
+
+	rec, body = call(http.MethodPut, chatWebhookPath, `{"url":"`+testChatHook+`","space_label":"Family dinner"}`)
+	wantMasked := "https://chat.googleapis.com/v1/spaces/AAQA1b2C3d4/messages?key=…&token=…ZxQ="
+	if rec.Code != http.StatusOK || body["configured"] != true || body["space_label"] != "Family dinner" || body["url_masked"] != wantMasked ||
+		body["last_test_at"] != nil || body["last_test_status"] != nil {
+		t.Errorf("PUT = %d %v", rec.Code, body)
+	}
+	if _, ok := body["url"]; ok {
+		t.Errorf("PUT response has a url field: %v", body)
+	}
+	rec, body = call(http.MethodGet, chatWebhookPath, "")
+	if rec.Code != http.StatusOK || body["space_label"] != "Family dinner" || body["url_masked"] != wantMasked {
+		t.Errorf("GET = %d %v", rec.Code, body)
+	}
+
+	rec, body = call(http.MethodPost, chatWebhookTestPath, "")
+	if rec.Code != http.StatusOK || body["http_status"] != float64(200) || body["last_test_status"] != "ok" || body["last_test_at"] == nil {
+		t.Errorf("POST test = %d %v, want 200 ok", rec.Code, body)
+	}
+	mu.Lock()
+	if len(received) != 1 || !strings.Contains(received[0], `"text":"MealQuest · test message"`) {
+		t.Errorf("Chat received %q, want the test message", received)
+	}
+	mu.Unlock()
+
+	setStatus(http.StatusForbidden)
+	rec, body = call(http.MethodPost, chatWebhookTestPath, "")
+	if rec.Code != http.StatusOK || body["http_status"] != float64(403) || body["last_test_status"] != "failed" {
+		t.Errorf("POST test answered 403 = %d %v, want 403 failed", rec.Code, body)
+	}
+	rec, body = call(http.MethodGet, chatWebhookPath, "")
+	if body["last_test_status"] != "failed" || body["last_test_at"] == nil {
+		t.Errorf("GET after a failed test = %d %v", rec.Code, body)
+	}
+
+	chatSrv.Close()
+	rec, body = call(http.MethodPost, chatWebhookTestPath, "")
+	if rec.Code != http.StatusBadGateway || body["error"].(map[string]any)["code"] != "chat_unreachable" {
+		t.Errorf("POST test against a stopped endpoint = %d %v, want 502 chat_unreachable", rec.Code, body)
+	}
+
+	tokenDecoded, _ := url.QueryUnescape(testChatToken)
+	for what, texts := range map[string][]string{"response": bodies, "log": {logs.String()}} {
+		for _, text := range texts {
+			for _, secret := range []string{testChatHook, testChatKey, testChatToken, tokenDecoded, testChatKey[:12], testChatToken[:12]} {
+				if strings.Contains(text, secret) {
+					t.Errorf("%s holds the webhook URL or a credential: %s", what, text)
+				}
+			}
+		}
+	}
+	if !strings.Contains(logs.String(), "chat webhook test failed") {
+		t.Errorf("log %q does not record the failed test, so the scan proves nothing", logs.String())
+	}
+}
+
+func TestChatWebhookNeedsCSRF(t *testing.T) {
+	t.Parallel()
+	router := newChatRouter(t, newTestChat(t), io.Discard)
+	for _, tc := range []struct{ method, target string }{
+		{http.MethodPut, chatWebhookPath},
+		{http.MethodPost, chatWebhookTestPath},
+	} {
+		req := httptest.NewRequest(tc.method, tc.target, strings.NewReader(`{"url":"`+testChatHook+`","space_label":"Family"}`))
+		req.AddCookie(validSessionCookie)
+		rec := httptest.NewRecorder()
+		router.ServeHTTP(rec, req)
+		if rec.Code != http.StatusForbidden {
+			t.Errorf("%s %s without CSRF token = %d, want 403", tc.method, tc.target, rec.Code)
+		}
+	}
+}
+
+func TestNewRouterRequiresChat(t *testing.T) {
+	t.Parallel()
+	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
+	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), nil, newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
+		t.Fatal("NewRouter accepted a nil Google Chat service")
+	}
+}
diff --git a/internal/server/dinners_test.go b/internal/server/dinners_test.go
index eb61c2f..3e363b9 100644
--- a/internal/server/dinners_test.go
+++ b/internal/server/dinners_test.go
@@ -91,7 +91,7 @@ func newDinnersEnv(t *testing.T) *dinnersEnv {
 	if err != nil {
 		t.Fatal(err)
 	}
-	e.h, err = NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t),
+	e.h, err = NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t),
 		svc, newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), runner, newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)
diff --git a/internal/server/google_test.go b/internal/server/google_test.go
index 5a87fd4..7d89bd0 100644
--- a/internal/server/google_test.go
+++ b/internal/server/google_test.go
@@ -68,7 +68,7 @@ func newGoogleEnv(t *testing.T) *googleEnv {
 		t.Fatal(err)
 	}
 	logger := slog.New(slog.NewJSONHandler(e.logs, &slog.HandlerOptions{Level: slog.LevelDebug}))
-	e.h, err = NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t),
+	e.h, err = NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t),
 		newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), svc, newTestPush(t), newTestRunner(t), newTestPhotos(t),
 		fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
diff --git a/internal/server/login_test.go b/internal/server/login_test.go
index 8d326b4..e4d416a 100644
--- a/internal/server/login_test.go
+++ b/internal/server/login_test.go
@@ -83,7 +83,7 @@ func newLoginRouter(t *testing.T, issuer string) http.Handler {
 		t.Fatal(err)
 	}
 	r, err := NewRouter(logger, "dev", trusted, flow, sessions, newTestSettings(t),
-		newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/internal/server/media_test.go b/internal/server/media_test.go
index eda9ff0..d0246e0 100644
--- a/internal/server/media_test.go
+++ b/internal/server/media_test.go
@@ -51,7 +51,7 @@ func newMediaRouter(t *testing.T) (r http.Handler, id, orphan string) {
 		t.Fatal(err)
 	}
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	r, err = NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t),
+	r, err = NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t),
 		photos, fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)
diff --git a/internal/server/origin_test.go b/internal/server/origin_test.go
index eac10b2..5325501 100644
--- a/internal/server/origin_test.go
+++ b/internal/server/origin_test.go
@@ -45,7 +45,7 @@ func newOriginRouter(t *testing.T, logs io.Writer) http.Handler {
 	}
 	logger := slog.New(forwarded.LogHandler(slog.NewJSONHandler(logs, nil)))
 	r, err := NewRouter(logger, "dev", trusted, probeAuth{}, stubSessions{}, newTestSettings(t),
-		newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/internal/server/plans_test.go b/internal/server/plans_test.go
index 88053e9..8d79900 100644
--- a/internal/server/plans_test.go
+++ b/internal/server/plans_test.go
@@ -93,7 +93,7 @@ func newPlansRouterTitled(t *testing.T, title shopping.Titler) plansEnv {
 	if err != nil {
 		t.Fatal(err)
 	}
-	h, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t),
+	h, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t),
 		newTestDinners(t), newTestSuggest(t), svc, shop, googleSvc, newTestPush(t), runner, newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)
diff --git a/internal/server/push_test.go b/internal/server/push_test.go
index 961e199..25e38a7 100644
--- a/internal/server/push_test.go
+++ b/internal/server/push_test.go
@@ -52,7 +52,7 @@ func newTestPushWith(t *testing.T) (*push.Service, *store.Store, vapid.KeyPair)
 func newPushRouter(t *testing.T, svc *push.Service) http.Handler {
 	t.Helper()
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	r, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), svc, newTestRunner(t),
+	r, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), svc, newTestRunner(t),
 		newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)
@@ -100,7 +100,7 @@ func TestNewRouterRequiresPush(t *testing.T) {
 	t.Parallel()
 
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), nil, newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
+	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), nil, newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil push service")
 	}
 }
diff --git a/internal/server/recipesearch_test.go b/internal/server/recipesearch_test.go
index 9869c1e..f912c29 100644
--- a/internal/server/recipesearch_test.go
+++ b/internal/server/recipesearch_test.go
@@ -22,7 +22,7 @@ const (
 func newRecipeSearchRouter(t *testing.T, search *recipes.SearchSettingsService) http.Handler {
 	t.Helper()
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	r, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), search, newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t),
+	r, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), search, newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t),
 		newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)
diff --git a/internal/server/server.go b/internal/server/server.go
index e0f4125..9413989 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -11,6 +11,7 @@ import (
 	"github.com/go-chi/chi/v5"
 
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/ai/aisettings"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/chat"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/dinners"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/forwarded"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/frontend"
@@ -40,6 +41,7 @@ type RouteMounter interface {
 // /media; settings serves /api/v1/settings/household; search serves
 // /api/v1/settings/recipe-search and its /test; ai serves
 // /api/v1/settings/ai, its /api-key, /verify, /models and /reset-prompt;
+// chatSvc serves GET and PUT /api/v1/settings/chat-webhook and its /test;
 // dinnerSvc serves GET and POST /api/v1/dinners, PATCH and DELETE
 // /api/v1/dinners/{id}, POST /api/v1/dinners/{id}/favorite, GET
 // /api/v1/dinners/{id}/recipe-candidates and POST /api/v1/dinners/{id}/ground;
@@ -63,7 +65,7 @@ type RouteMounter interface {
 // GET /media/photos/{id}-{size}.jpg; assets is the web build
 // served for every other GET. /health, /auth and the web build are public.
 // Requests to /api/v1 other than GET also need the session's CSRF token in CSRFHeader.
-func NewRouter(logger *slog.Logger, version string, trusted forwarded.Trusted, auth RouteMounter, sessions SessionLookup, settings *household.SettingsService, search *recipes.SearchSettingsService, ai *aisettings.Service, dinnerSvc *dinners.Service, suggestSvc *suggest.Service, planSvc *plan.Service, shopSvc *shopping.Service, googleSvc *gcal.Service, pushSvc *push.Service, runner *jobs.Runner, photos PhotoFiles, assets fs.FS) (http.Handler, error) {
+func NewRouter(logger *slog.Logger, version string, trusted forwarded.Trusted, auth RouteMounter, sessions SessionLookup, settings *household.SettingsService, search *recipes.SearchSettingsService, ai *aisettings.Service, chatSvc *chat.Service, dinnerSvc *dinners.Service, suggestSvc *suggest.Service, planSvc *plan.Service, shopSvc *shopping.Service, googleSvc *gcal.Service, pushSvc *push.Service, runner *jobs.Runner, photos PhotoFiles, assets fs.FS) (http.Handler, error) {
 	if settings == nil {
 		return nil, errors.New("server: nil household settings service")
 	}
@@ -73,6 +75,9 @@ func NewRouter(logger *slog.Logger, version string, trusted forwarded.Trusted, a
 	if ai == nil {
 		return nil, errors.New("server: nil AI settings service")
 	}
+	if chatSvc == nil {
+		return nil, errors.New("server: nil Google Chat service")
+	}
 	if dinnerSvc == nil {
 		return nil, errors.New("server: nil dinners service")
 	}
@@ -134,6 +139,9 @@ func NewRouter(logger *slog.Logger, version string, trusted forwarded.Trusted, a
 	apiV1.Post("/settings/ai/verify", postAIVerify(logger, ai))
 	apiV1.Get("/settings/ai/models", getAIModels(logger, ai))
 	apiV1.Post("/settings/ai/reset-prompt", postAIResetPrompt(logger, ai))
+	apiV1.Get("/settings/chat-webhook", getChatWebhook(logger, chatSvc))
+	apiV1.Put("/settings/chat-webhook", putChatWebhook(logger, chatSvc))
+	apiV1.Post("/settings/chat-webhook/test", postChatWebhookTest(logger, chatSvc))
 	apiV1.Get("/dinners", getDinners(logger, dinnerSvc))
 	apiV1.Post("/dinners", postDinner(logger, dinnerSvc))
 	apiV1.Patch("/dinners/{id}", patchDinner(logger, dinnerSvc))
diff --git a/internal/server/server_test.go b/internal/server/server_test.go
index 70fee30..acf75cb 100644
--- a/internal/server/server_test.go
+++ b/internal/server/server_test.go
@@ -54,7 +54,7 @@ func newTestRouterWith(t *testing.T, version string, settings *household.Setting
 		"index.html":             {Data: []byte(fixtureIndex)},
 		"assets/index-AbC123.js": {Data: []byte(fixtureAsset)},
 	}
-	r, err := NewRouter(logger, version, nil, stubAuth{}, stubSessions{}, settings, newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), runner, newTestPhotos(t), assets)
+	r, err := NewRouter(logger, version, nil, stubAuth{}, stubSessions{}, settings, newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), runner, newTestPhotos(t), assets)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -287,7 +287,7 @@ func TestNewRouterRequiresAISettings(t *testing.T) {
 	t.Parallel()
 
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), nil, newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
+	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), nil, newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil AI settings service")
 	}
 }
@@ -296,7 +296,7 @@ func TestNewRouterRequiresSearchSettings(t *testing.T) {
 	t.Parallel()
 
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), nil, newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
+	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), nil, newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil recipe search settings service")
 	}
 }
@@ -305,7 +305,7 @@ func TestNewRouterRequiresPhotoFiles(t *testing.T) {
 	t.Parallel()
 
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), nil, fstest.MapFS{"index.html": {}}); err == nil {
+	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), nil, fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted nil photo files")
 	}
 }
@@ -314,7 +314,7 @@ func TestNewRouterRequiresSettings(t *testing.T) {
 	t.Parallel()
 
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, nil, newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
+	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, nil, newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil settings service")
 	}
 }
@@ -323,7 +323,7 @@ func TestNewRouterRequiresDinners(t *testing.T) {
 	t.Parallel()
 
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), nil, newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
+	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t), nil, newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil dinners service")
 	}
 }
@@ -332,7 +332,7 @@ func TestNewRouterRequiresSuggestions(t *testing.T) {
 	t.Parallel()
 
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestDinners(t), nil, newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
+	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), nil, newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil suggestions service")
 	}
 }
@@ -341,7 +341,7 @@ func TestNewRouterRequiresPlan(t *testing.T) {
 	t.Parallel()
 
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), nil, newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
+	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), nil, newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil plan service")
 	}
 }
@@ -350,7 +350,7 @@ func TestNewRouterRequiresShopping(t *testing.T) {
 	t.Parallel()
 
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), nil, newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
+	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), nil, newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil shopping service")
 	}
 }
@@ -359,7 +359,7 @@ func TestNewRouterRequiresGoogle(t *testing.T) {
 	t.Parallel()
 
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), nil, newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
+	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), nil, newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil Google Calendar service")
 	}
 }
@@ -368,7 +368,7 @@ func TestNewRouterRequiresJobRunner(t *testing.T) {
 	t.Parallel()
 
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
-	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), nil, newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
+	if _, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), nil, newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil job runner")
 	}
 }
diff --git a/internal/server/settings_test.go b/internal/server/settings_test.go
index 0498264..58bba10 100644
--- a/internal/server/settings_test.go
+++ b/internal/server/settings_test.go
@@ -277,7 +277,7 @@ func TestHouseholdSettingsWithRealSession(t *testing.T) {
 	}
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
 	router, err := NewRouter(logger, "dev", nil, stubAuth{}, sessions, household.NewSettingsService(st),
-		newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		newTestSearch(t), newTestAI(t), newTestChat(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/internal/server/suggestions_test.go b/internal/server/suggestions_test.go
index 78106d0..e1b8938 100644
--- a/internal/server/suggestions_test.go
+++ b/internal/server/suggestions_test.go
@@ -44,7 +44,7 @@ func newSuggestionsRouter(t *testing.T, names ...string) (http.Handler, *store.S
 	if err != nil {
 		t.Fatal(err)
 	}
-	h, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t),
+	h, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestChat(t),
 		newTestDinners(t), svc, newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestPush(t), runner, newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)
diff --git a/migrations/queries/settings.sql b/migrations/queries/settings.sql
index d9983ec..f40a0d7 100644
--- a/migrations/queries/settings.sql
+++ b/migrations/queries/settings.sql
@@ -146,3 +146,11 @@ ON CONFLICT (id) DO UPDATE SET
 	last_test_status = excluded.last_test_status,
 	updated_at = excluded.updated_at
 RETURNING *;
+
+-- name: RecordChatTest :execrows
+-- Records the outcome of a test message sent to the webhook sealed in
+-- webhook_url_ct; affects no row when the webhook has been replaced or
+-- removed since the test began.
+UPDATE chat_settings
+SET last_test_at = ?, last_test_status = ?, updated_at = ?
+WHERE id = 1 AND webhook_url_ct = ?;