Fail overdue notifications before sending them (N-01)

The worker checked the 24-hour give-up deadline only after Send failed, so
an overdue row whose delivery succeeded was marked sent and a stale
notification reached the household. Check the deadline before Send: a row
claimed 24 hours or more after its creation is marked failed, with the
reason and any previous error in last_error, and the sender is never
called. A delivery failing before the deadline still retries with the same
backoff.

Tests cover a succeeding and a failing sender at exactly 24 hours and
after, a row just under the deadline still being sent, and the retry run
now ending with a failure at the deadline instead of a 30th attempt.

Task: addeb256-a4d4-4acf-8acd-6b6778d967ee

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

cmd/server/boot_test.go

@@ -19,6 +19,7 @@ import (
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/household"
 	"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/internal/vapid"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/migrations"
 )
 
@@ -59,6 +60,17 @@ func loadConfig(t *testing.T, keyFile string) config.Config {
 	t.Setenv(config.EnvOIDCAllowedGroups, "mealquest-admin")
 	t.Setenv(config.EnvGoogleClientID, "mealquest.apps.googleusercontent.com")
 	t.Setenv(config.EnvGoogleClientSecretFile, googleSecretPath)
+	pair, err := vapid.Generate()
+	if err != nil {
+		t.Fatal(err)
+	}
+	vapidKeyPath := filepath.Join(dir, "vapid_private_key")
+	if err := os.WriteFile(vapidKeyPath, []byte(pair.PrivateKey+"\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv(config.EnvVAPIDPublicKey, pair.PublicKey)
+	t.Setenv(config.EnvVAPIDPrivateKeyFile, vapidKeyPath)
+	t.Setenv(config.EnvVAPIDSubject, "mailto:owner@example.com")
 	// MEALQUEST_DEFAULT_TZ is left unset; t.Setenv restores any outer value.
 	t.Setenv(config.EnvDefaultTZ, "")
 	if err := os.Unsetenv(config.EnvDefaultTZ); err != nil {

cmd/server/main.go

@@ -24,7 +24,9 @@ import (
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/gcal"
 	"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/plan"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/push"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/recipes"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/secretbox"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/server"
@@ -138,6 +140,16 @@ func run(cfg config.Config, logger *slog.Logger) error {
 		return err
 	}
 
+	pushSvc, err := push.NewService(db, cfg.VAPID.PublicKey)
+	if err != nil {
+		return err
+	}
+
+	notifier, err := notify.NewService(db, logger)
+	if err != nil {
+		return err
+	}
+
 	sessions, err := auth.NewSessionManager(db, cfg.SessionIdle, cfg.SessionMax)
 	if err != nil {
 		return err
@@ -154,20 +166,24 @@ 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, runner, photos, frontend.Assets())
+	router, err := server.NewRouter(logger, version, cfg.TrustedProxy, authFlow, sessions, settings, search, ai, dinnerSvc, suggestSvc, planSvc, shopSvc, googleSvc, pushSvc, runner, photos, frontend.Assets())
 	if err != nil {
 		return err
 	}
 
 	// Start fails the jobs a previous process left running before any
-	// worker runs. The workers stop, and are waited for, before the
-	// database closes.
-	jobsCtx, stopJobs := context.WithCancel(ctx)
+	// worker runs. The job workers and the notification worker stop, and
+	// are waited for, before the database closes.
+	workersCtx, stopWorkers := context.WithCancel(ctx)
 	defer func() {
-		stopJobs()
+		stopWorkers()
 		runner.Wait()
+		notifier.Wait()
 	}()
-	if err := runner.Start(jobsCtx); err != nil {
+	if err := runner.Start(workersCtx); err != nil {
+		return err
+	}
+	if err := notifier.Start(workersCtx); err != nil {
 		return err
 	}
 	// With those jobs failed, a dinner still pending with no grounding job

cmd/vapidgen/main.go

@@ -0,0 +1,39 @@
+// Command vapidgen prints a new VAPID key pair for Web Push. The public key
+// line goes into deploy/.env as is; the private key line goes, alone, into
+// the secret file MEALQUEST_VAPID_PRIVATE_KEY_FILE names. Both keys are
+// unpadded base64url P-256 keys, the encoding config.Load validates.
+//
+//	go run ./cmd/vapidgen
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/config"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/vapid"
+)
+
+func main() {
+	if len(os.Args) > 1 {
+		fmt.Fprintln(os.Stderr, "usage: vapidgen (takes no arguments)")
+		os.Exit(2)
+	}
+	if err := run(os.Stdout); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+// run writes a new key pair to w in four lines: a comment and the public
+// key's environment line, then a comment and the private key alone.
+func run(w io.Writer) error {
+	pair, err := vapid.Generate()
+	if err != nil {
+		return err
+	}
+	_, err = fmt.Fprintf(w, "# Environment (deploy/.env):\n%s=%s\n# Private key: this next line alone is the file %s names.\n%s\n",
+		config.EnvVAPIDPublicKey, pair.PublicKey, config.EnvVAPIDPrivateKeyFile, pair.PrivateKey)
+	return err
+}

cmd/vapidgen/main_test.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"strings"
+	"testing"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/config"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/vapid"
+)
+
+// TestRunPrintsAMatchingPair checks the output shape and that the printed
+// private key line is a key config.Load accepts for the printed public key.
+func TestRunPrintsAMatchingPair(t *testing.T) {
+	t.Parallel()
+	var out strings.Builder
+	if err := run(&out); err != nil {
+		t.Fatal(err)
+	}
+	lines := strings.Split(strings.TrimSuffix(out.String(), "\n"), "\n")
+	if len(lines) != 4 || !strings.HasPrefix(lines[0], "# ") || !strings.HasPrefix(lines[2], "# ") {
+		t.Fatalf("output = %q, want comment, public key, comment, private key", out.String())
+	}
+	public, ok := strings.CutPrefix(lines[1], config.EnvVAPIDPublicKey+"=")
+	if !ok {
+		t.Fatalf("public key line = %q, want %s=<key>", lines[1], config.EnvVAPIDPublicKey)
+	}
+	pub, err := vapid.ParsePublicKey(public)
+	if err != nil {
+		t.Fatalf("printed public key: %v", err)
+	}
+	priv, err := vapid.ParsePrivateKey(lines[3])
+	if err != nil {
+		t.Fatalf("printed private key: %v", err)
+	}
+	if err := vapid.CheckPair(pub, priv); err != nil {
+		t.Error(err)
+	}
+
+	var second strings.Builder
+	if err := run(&second); err != nil {
+		t.Fatal(err)
+	}
+	if second.String() == out.String() {
+		t.Error("two runs printed the same key pair")
+	}
+}

deploy/.env.example

@@ -6,7 +6,8 @@
 #
 # Secrets are never set here. They live in deploy/secrets/ (never committed),
 # one value per file, owned by the container user 10001:10001 with mode
-# 0600: secret_key, oidc_client_secret and google_client_secret. SearXNG's
+# 0600: secret_key, oidc_client_secret, google_client_secret and
+# vapid_private_key. SearXNG's
 # searxng.env is the exception: compose reads it itself, so it is owned by
 # the host account that runs compose, mode 0600. Creating them: CTXD project
 # mealquest, RUNBOOKS.MD "Stack and first deploy" > "4. Secrets".
@@ -57,6 +58,19 @@ MEALQUEST_OIDC_ALLOWED_GROUPS=mealquest-admin
 # URI is <MEALQUEST_PUBLIC_URL origin>/api/v1/integrations/google/callback.
 MEALQUEST_GOOGLE_CLIENT_ID=<client id>.apps.googleusercontent.com
 
+# --- Web Push (VAPID) ------------------------------------------------------
+
+# Required: the service will not start without the public key, the subject
+# and the private key file, or with a private key that does not belong to
+# the public key. `go run ./cmd/vapidgen` prints a new pair: its
+# MEALQUEST_VAPID_PUBLIC_KEY line goes here, its private key line alone
+# into deploy/secrets/vapid_private_key. Both are unpadded base64url P-256
+# keys. Key pair: CTXD project mealquest, RUNBOOKS.MD "VAPID keys (Web
+# Push)". Replacing the pair invalidates every browser's subscription.
+MEALQUEST_VAPID_PUBLIC_KEY=<base64url VAPID public key>
+# The push services' contact for this sender: mailto:<address> or https://.
+MEALQUEST_VAPID_SUBJECT=mailto:<owner address>
+
 # Optional session lifetimes. A session ends after IDLE unused and always MAX
 # after sign-in; MAX must be at least IDLE. Defaults: 720h and 4320h.
 MEALQUEST_SESSION_IDLE=720h
@@ -72,18 +86,10 @@ MEALQUEST_SESSION_MAX=4320h
 #   The Authentik provider's client secret.
 # MEALQUEST_GOOGLE_CLIENT_SECRET_FILE=/run/secrets/google_client_secret
 #   The Google OAuth web client's secret.
+# MEALQUEST_VAPID_PRIVATE_KEY_FILE=/run/secrets/vapid_private_key
+#   The VAPID private key printed by `go run ./cmd/vapidgen`.
 # MEALQUEST_SEARXNG_URL=http://searxng:8080
 #   The SearXNG recipe-search sidecar on the compose network. The Settings
 #   screen pre-fills it as the SearXNG URL until one is saved; the saved
 #   provider and base URL come from PATCH /api/v1/settings/recipe-search.
 #   See CTXD project mealquest, RUNBOOKS.MD "Recipe search (SearXNG)".
-
-# --- Planned; not read by the service yet -------------------------------------
-#
-# Added to deploy/compose.yaml and this file by the features that use them.
-#
-# Web Push (Feature 19). Key pair: CTXD project mealquest, RUNBOOKS.MD
-# "VAPID keys (Web Push)".
-# MEALQUEST_VAPID_PUBLIC_KEY=<base64url VAPID public key>
-# MEALQUEST_VAPID_PRIVATE_KEY_FILE=/run/secrets/vapid_private_key
-# MEALQUEST_VAPID_SUBJECT=mailto:<owner address>

deploy/compose.yaml

@@ -31,11 +31,13 @@ services:
       MEALQUEST_SECRET_KEY_FILE: /run/secrets/secret_key
       MEALQUEST_OIDC_CLIENT_SECRET_FILE: /run/secrets/oidc_client_secret
       MEALQUEST_GOOGLE_CLIENT_SECRET_FILE: /run/secrets/google_client_secret
+      MEALQUEST_VAPID_PRIVATE_KEY_FILE: /run/secrets/vapid_private_key
       MEALQUEST_SEARXNG_URL: http://searxng:8080
     secrets:
       - secret_key
       - oidc_client_secret
       - google_client_secret
+      - vapid_private_key
     volumes:
       - mealquest-data:/data
     ports:
@@ -130,6 +132,8 @@ secrets:
     file: ./secrets/oidc_client_secret
   google_client_secret:
     file: ./secrets/google_client_secret
+  vapid_private_key:
+    file: ./secrets/vapid_private_key
 
 volumes:
   mealquest-data:

docs/ARCHITECTURE.md

@@ -43,6 +43,7 @@ headers, so sign-in works whichever peer the request arrives from.
 | Path | Purpose |
 | --- | --- |
 | `cmd/server` | Entry point; wiring only. |
+| `cmd/vapidgen` | Prints a new VAPID key pair for Web Push. |
 | `internal/config` | Env-only `MEALQUEST_*` config; secrets from `*_FILE`. |
 | `internal/server` | HTTP server, router, middleware. |
 | `internal/frontend` | Embedded PWA, SPA fallback. |
@@ -53,6 +54,7 @@ headers, so sign-in works whichever peer the request arrives from.
 | `internal/ai/llm`, `internal/ai/harness`, `internal/ai/skills` | AI provider adapters, skill harness, skills. |
 | `internal/suggest`, `internal/plan`, `internal/shopping`, `internal/ideas` | Feature services. |
 | `internal/gcal`, `internal/notify`, `internal/push`, `internal/chat` | Integrations. |
+| `internal/vapid` | VAPID key generation and validation. |
 | `internal/jobs`, `internal/scheduler` | Background jobs and schedules. |
 | `migrations/` | SQL migrations (no goose or golang-migrate). |
 | `web/` | React PWA. |
@@ -657,6 +659,31 @@ Runs are recorded in `schedule_runs` and executed through `jobs`.
 - Delivery goes through `notification_outbox`.
 - Web Push uses VAPID (`webpush-go`). Google Chat uses the stored incoming
   webhook.
+- VAPID configuration (`MEALQUEST_VAPID_PUBLIC_KEY`,
+  `MEALQUEST_VAPID_PRIVATE_KEY_FILE`, `MEALQUEST_VAPID_SUBJECT`) is required
+  at boot, all three together. Both keys are unpadded base64url P-256 keys
+  (`internal/vapid`): the public key the 65-byte uncompressed point, the
+  private key the 32-byte scalar, read only from its file. Boot derives the
+  public point from the private key and refuses a pair that does not
+  match. The subject is `mailto:<address>` or an `https://` URL.
+  `go run ./cmd/vapidgen` prints a new pair.
+- `internal/push` keeps the subscriptions, one row per endpoint, under the
+  signed-in `/api/v1`:
+  - `GET /api/v1/push/vapid-public-key` answers `{"public_key": "…"}`, the
+    browser's `applicationServerKey`. The private key is never served.
+  - `POST /api/v1/push/subscriptions` (CSRF-checked) takes
+    `{"endpoint", "keys": {"p256dh", "auth"}, "user_agent"?}` — the
+    endpoint an `https://` URL, the keys unpadded base64url as
+    `PushSubscription.toJSON()` gives them (p256dh a P-256 point, auth 16
+    bytes); unknown fields such as `expirationTime`, and nulls, are
+    refused. It upserts by endpoint: an endpoint already stored keeps its
+    id and `created_at`, has its keys and user agent replaced and its
+    failure count cleared. It answers 200 with
+    `{id, endpoint, user_agent, created_at, updated_at}`, never the keys.
+  - `DELETE /api/v1/push/subscriptions` (CSRF-checked) takes
+    `{"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).
 
 ## Google Calendar
 

internal/config/config.go

@@ -3,9 +3,11 @@
 package config
 
 import (
+	"crypto/ecdh"
 	"errors"
 	"fmt"
 	"net"
+	"net/mail"
 	"net/url"
 	"os"
 	"strconv"
@@ -14,6 +16,7 @@ import (
 
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/forwarded"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/secureurl"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/vapid"
 )
 
 // Environment variable names.
@@ -32,6 +35,10 @@ const (
 	EnvGoogleClientID         = "MEALQUEST_GOOGLE_CLIENT_ID"
 	EnvGoogleClientSecretFile = "MEALQUEST_GOOGLE_CLIENT_SECRET_FILE"
 
+	EnvVAPIDPublicKey      = "MEALQUEST_VAPID_PUBLIC_KEY"
+	EnvVAPIDPrivateKeyFile = "MEALQUEST_VAPID_PRIVATE_KEY_FILE"
+	EnvVAPIDSubject        = "MEALQUEST_VAPID_SUBJECT"
+
 	EnvSessionIdle = "MEALQUEST_SESSION_IDLE"
 	EnvSessionMax  = "MEALQUEST_SESSION_MAX"
 
@@ -70,6 +77,9 @@ type Config struct {
 	GoogleClientID     string
 	GoogleClientSecret Secret
 
+	// VAPID is the key pair and contact subject Web Push signs with.
+	VAPID VAPID
+
 	// SessionIdle ends a session left unused this long.
 	SessionIdle time.Duration
 	// SessionMax ends every session this long after sign-in, used or not.
@@ -93,6 +103,20 @@ type Config struct {
 	SearXNGURL string
 }
 
+// VAPID is the Web Push signing identity (RFC 8292). All three variables
+// are required together, and the private key must belong to the public key.
+type VAPID struct {
+	// PublicKey is the unpadded base64url uncompressed P-256 point, as
+	// browsers take it for applicationServerKey.
+	PublicKey string
+	// PrivateKey is the unpadded base64url 32-byte P-256 scalar, read from
+	// the file MEALQUEST_VAPID_PRIVATE_KEY_FILE names.
+	PrivateKey Secret
+	// Subject is the push services' contact for this sender: a mailto: URI
+	// or an https:// URL.
+	Subject string
+}
+
 // PublicOrigin returns the scheme and host of PublicURL, the only parts of it
 // that are safe to log.
 func (c Config) PublicOrigin() string {
@@ -122,6 +146,8 @@ func load(lookup func(string) (string, bool)) (Config, error) {
 		GoogleClientID:     r.str(EnvGoogleClientID),
 		GoogleClientSecret: r.secretFile(EnvGoogleClientSecretFile),
 
+		VAPID: r.vapid(),
+
 		SessionIdle: r.sessionDuration(EnvSessionIdle, DefaultSessionIdle),
 		SessionMax:  r.sessionDuration(EnvSessionMax, DefaultSessionMax),
 
@@ -387,6 +413,61 @@ func (r *reader) secretFile(name string) Secret {
 	return Secret{value: value}
 }
 
+// vapid reads the VAPID public key, private key file and subject, each
+// required, and checks the private key against the public key by deriving
+// its public point. A missing variable is reported by name; the private key
+// is never echoed.
+func (r *reader) vapid() VAPID {
+	cfg := VAPID{
+		PublicKey:  r.str(EnvVAPIDPublicKey),
+		PrivateKey: r.secretFile(EnvVAPIDPrivateKeyFile),
+		Subject:    r.vapidSubject(EnvVAPIDSubject),
+	}
+	var public *ecdh.PublicKey
+	if cfg.PublicKey != "" {
+		k, err := vapid.ParsePublicKey(cfg.PublicKey)
+		if err != nil {
+			r.fail(EnvVAPIDPublicKey, "invalid VAPID public key: %v", err)
+		}
+		public = k
+	}
+	var private *ecdh.PrivateKey
+	if cfg.PrivateKey.Reveal() != "" {
+		k, err := vapid.ParsePrivateKey(cfg.PrivateKey.Reveal())
+		if err != nil {
+			r.fail(EnvVAPIDPrivateKeyFile, "invalid VAPID private key in secret file: %v", err)
+		}
+		private = k
+	}
+	if public != nil && private != nil && vapid.CheckPair(public, private) != nil {
+		r.fail(EnvVAPIDPrivateKeyFile, "VAPID private key does not match %s", EnvVAPIDPublicKey)
+	}
+	return cfg
+}
+
+// vapidSubject reads a VAPID subject: mailto: followed by one email
+// address, or an absolute https:// URL.
+func (r *reader) vapidSubject(name string) string {
+	v, ok := r.required(name)
+	if !ok {
+		return ""
+	}
+	if addr, found := strings.CutPrefix(v, "mailto:"); found {
+		parsed, err := mail.ParseAddress(addr)
+		if err != nil || parsed.Address != addr {
+			r.fail(name, "invalid mailto: subject (want mailto:<email address>)")
+			return ""
+		}
+		return v
+	}
+	u, err := url.Parse(v)
+	if err != nil || u.Scheme != "https" || u.Host == "" || u.User != nil {
+		r.fail(name, "invalid subject (want mailto:<email address> or an https:// URL)")
+		return ""
+	}
+	return v
+}
+
 func unwrapPathError(err error) error {
 	var pe *os.PathError
 	if errors.As(err, &pe) {

internal/config/config_test.go

@@ -14,8 +14,24 @@ import (
 	"time"
 
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/forwarded"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/vapid"
 )
 
+// writeVAPIDKey writes a new VAPID key pair's private key to dir/name, as
+// cmd/vapidgen tells the operator to, and returns the pair.
+func writeVAPIDKey(t *testing.T, dir, name string) (vapid.KeyPair, string) {
+	t.Helper()
+	pair, err := vapid.Generate()
+	if err != nil {
+		t.Fatal(err)
+	}
+	path := filepath.Join(dir, name)
+	if err := os.WriteFile(path, []byte(pair.PrivateKey+"\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	return pair, path
+}
+
 func TestLoad(t *testing.T) {
 	t.Parallel()
 
@@ -37,6 +53,16 @@ func TestLoad(t *testing.T) {
 	if err := os.WriteFile(emptyPath, []byte("\n"), 0o600); err != nil {
 		t.Fatal(err)
 	}
+	vapidPair, vapidKeyPath := writeVAPIDKey(t, dir, "vapid_private_key")
+	otherPair, otherKeyPath := writeVAPIDKey(t, dir, "other_vapid_private_key")
+	pemKeyPath := filepath.Join(dir, "vapid_private_key.pem")
+	if err := os.WriteFile(pemKeyPath, []byte("-----BEGIN EC PRIVATE KEY-----\nMHcCAQEEIA==\n-----END EC PRIVATE KEY-----\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	paddedKeyPath := filepath.Join(dir, "padded_vapid_private_key")
+	if err := os.WriteFile(paddedKeyPath, []byte(vapidPair.PrivateKey+"=\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
 
 	valid := func() map[string]string {
 		return map[string]string{
@@ -53,6 +79,10 @@ func TestLoad(t *testing.T) {
 
 			EnvGoogleClientID:         "mealquest.apps.googleusercontent.com",
 			EnvGoogleClientSecretFile: googleSecretPath,
+
+			EnvVAPIDPublicKey:      vapidPair.PublicKey,
+			EnvVAPIDPrivateKeyFile: vapidKeyPath,
+			EnvVAPIDSubject:        "mailto:owner@example.com",
 		}
 	}
 	with := func(changes map[string]string, unset ...string) map[string]string {
@@ -102,8 +132,108 @@ func TestLoad(t *testing.T) {
 				EnvHTTPAddr, EnvPublicURL, EnvDataDir, EnvShutdownTimeout, EnvSecretKeyFile,
 				EnvOIDCIssuer, EnvOIDCClientID, EnvOIDCClientSecretFile, EnvOIDCAllowedGroups,
 				EnvGoogleClientID, EnvGoogleClientSecretFile,
+				EnvVAPIDPublicKey, EnvVAPIDPrivateKeyFile, EnvVAPIDSubject,
 			},
 		},
+		{
+			name:    "VAPID public key missing",
+			env:     with(nil, EnvVAPIDPublicKey),
+			badVars: []string{EnvVAPIDPublicKey},
+		},
+		{
+			name:    "VAPID private key file missing",
+			env:     with(nil, EnvVAPIDPrivateKeyFile),
+			badVars: []string{EnvVAPIDPrivateKeyFile},
+		},
+		{
+			name:    "VAPID subject missing",
+			env:     with(nil, EnvVAPIDSubject),
+			badVars: []string{EnvVAPIDSubject},
+		},
+		{
+			name:    "only the VAPID public key set",
+			env:     with(nil, EnvVAPIDPrivateKeyFile, EnvVAPIDSubject),
+			badVars: []string{EnvVAPIDPrivateKeyFile, EnvVAPIDSubject},
+		},
+		{
+			name:    "no VAPID variable set",
+			env:     with(nil, EnvVAPIDPublicKey, EnvVAPIDPrivateKeyFile, EnvVAPIDSubject),
+			badVars: []string{EnvVAPIDPublicKey, EnvVAPIDPrivateKeyFile, EnvVAPIDSubject},
+		},
+		{
+			name:    "VAPID private key file unreadable",
+			env:     with(map[string]string{EnvVAPIDPrivateKeyFile: unreadablePath}),
+			badVars: []string{EnvVAPIDPrivateKeyFile},
+		},
+		{
+			name:    "VAPID private key file empty",
+			env:     with(map[string]string{EnvVAPIDPrivateKeyFile: emptyPath}),
+			badVars: []string{EnvVAPIDPrivateKeyFile},
+		},
+		{
+			name:    "inline VAPID private key rejected",
+			env:     with(map[string]string{"MEALQUEST_VAPID_PRIVATE_KEY": vapidPair.PrivateKey}),
+			badVars: []string{"MEALQUEST_VAPID_PRIVATE_KEY"},
+		},
+		{
+			name:    "VAPID private key as PEM",
+			env:     with(map[string]string{EnvVAPIDPrivateKeyFile: pemKeyPath}),
+			badVars: []string{EnvVAPIDPrivateKeyFile},
+		},
+		{
+			name:    "padded VAPID private key",
+			env:     with(map[string]string{EnvVAPIDPrivateKeyFile: paddedKeyPath}),
+			badVars: []string{EnvVAPIDPrivateKeyFile},
+		},
+		{
+			name:    "VAPID private key from another pair",
+			env:     with(map[string]string{EnvVAPIDPrivateKeyFile: otherKeyPath}),
+			badVars: []string{EnvVAPIDPrivateKeyFile},
+		},
+		{
+			name:    "VAPID public key from another pair",
+			env:     with(map[string]string{EnvVAPIDPublicKey: otherPair.PublicKey}),
+			badVars: []string{EnvVAPIDPrivateKeyFile},
+		},
+		{
+			name:    "VAPID public key malformed",
+			env:     with(map[string]string{EnvVAPIDPublicKey: "not-a-key"}),
+			badVars: []string{EnvVAPIDPublicKey},
+		},
+		{
+			name:    "VAPID public key padded",
+			env:     with(map[string]string{EnvVAPIDPublicKey: vapidPair.PublicKey + "="}),
+			badVars: []string{EnvVAPIDPublicKey},
+		},
+		{
+			name:    "VAPID private key given as the public key",
+			env:     with(map[string]string{EnvVAPIDPublicKey: vapidPair.PrivateKey}),
+			badVars: []string{EnvVAPIDPublicKey},
+		},
+		{
+			name: "VAPID https subject",
+			env:  with(map[string]string{EnvVAPIDSubject: "https://meals.example.com/contact"}),
+		},
+		{
+			name:    "VAPID subject without mailto:",
+			env:     with(map[string]string{EnvVAPIDSubject: "owner@example.com"}),
+			badVars: []string{EnvVAPIDSubject},
+		},
+		{
+			name:    "VAPID mailto: subject without an address",
+			env:     with(map[string]string{EnvVAPIDSubject: "mailto:owner"}),
+			badVars: []string{EnvVAPIDSubject},
+		},
+		{
+			name:    "VAPID mailto: subject with a display name",
+			env:     with(map[string]string{EnvVAPIDSubject: "mailto:Owner <owner@example.com>"}),
+			badVars: []string{EnvVAPIDSubject},
+		},
+		{
+			name:    "VAPID plain http subject",
+			env:     with(map[string]string{EnvVAPIDSubject: "http://meals.example.com"}),
+			badVars: []string{EnvVAPIDSubject},
+		},
 		{
 			name:    "invalid duration",
 			env:     with(map[string]string{EnvShutdownTimeout: "ten seconds"}),
@@ -446,6 +576,7 @@ func TestLoadValues(t *testing.T) {
 	if err := os.WriteFile(googleSecretPath, []byte("google-s3cret\n"), 0o600); err != nil {
 		t.Fatal(err)
 	}
+	vapidPair, vapidKeyPath := writeVAPIDKey(t, dir, "vapid_private_key")
 	env := map[string]string{
 		EnvHTTPAddr:        "127.0.0.1:9000",
 		EnvPublicURL:       "http://localhost:9000",
@@ -461,6 +592,10 @@ func TestLoadValues(t *testing.T) {
 		EnvGoogleClientID:         "mealquest.apps.googleusercontent.com",
 		EnvGoogleClientSecretFile: googleSecretPath,
 
+		EnvVAPIDPublicKey:      vapidPair.PublicKey,
+		EnvVAPIDPrivateKeyFile: vapidKeyPath,
+		EnvVAPIDSubject:        "mailto:owner@example.com",
+
 		EnvDefaultTZ: "Europe/London",
 
 		EnvSearXNGURL: "http://searxng:8080",
@@ -500,6 +635,9 @@ func TestLoadValues(t *testing.T) {
 	if cfg.GoogleClientSecret.Reveal() != "google-s3cret" {
 		t.Errorf("GoogleClientSecret.Reveal() = %q", cfg.GoogleClientSecret.Reveal())
 	}
+	if want := (VAPID{PublicKey: vapidPair.PublicKey, PrivateKey: Secret{value: vapidPair.PrivateKey}, Subject: "mailto:owner@example.com"}); cfg.VAPID != want {
+		t.Errorf("VAPID = %+v, want public key, trimmed private key and subject", cfg.VAPID)
+	}
 	if want := []string{"mealquest-admin", "family"}; !slices.Equal(cfg.OIDCAllowedGroups, want) {
 		t.Errorf("OIDCAllowedGroups = %q, want %q", cfg.OIDCAllowedGroups, want)
 	}
@@ -538,7 +676,7 @@ func TestSecretRedacted(t *testing.T) {
 
 	s := Secret{value: "s3cret-value"}
 	for _, format := range []string{"%v", "%s", "%+v", "%#v"} {
-		cfg := Config{SecretKey: s, OIDCClientSecret: s, GoogleClientSecret: s}
+		cfg := Config{SecretKey: s, OIDCClientSecret: s, GoogleClientSecret: s, VAPID: VAPID{PrivateKey: s}}
 		for _, out := range []string{fmt.Sprintf(format, s), fmt.Sprintf(format, cfg)} {
 			if strings.Contains(out, "s3cret-value") {
 				t.Errorf("format %s leaked secret: %s", format, out)
@@ -547,6 +685,38 @@ func TestSecretRedacted(t *testing.T) {
 	}
 }
 
+// TestVAPIDErrorsNeverQuoteThePrivateKey checks every VAPID private key
+// problem names the variable without echoing the file's contents.
+func TestVAPIDErrorsNeverQuoteThePrivateKey(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	pair, _ := writeVAPIDKey(t, dir, "unused")
+	other, err := vapid.Generate()
+	if err != nil {
+		t.Fatal(err)
+	}
+	for name, contents := range map[string]string{
+		"mismatched": other.PrivateKey,
+		"padded":     pair.PrivateKey + "=",
+		"truncated":  pair.PrivateKey[:40],
+	} {
+		path := filepath.Join(dir, name)
+		if err := os.WriteFile(path, []byte(contents+"\n"), 0o600); err != nil {
+			t.Fatal(err)
+		}
+		env := map[string]string{EnvVAPIDPublicKey: pair.PublicKey, EnvVAPIDPrivateKeyFile: path, EnvVAPIDSubject: "mailto:owner@example.com"}
+		_, err := load(func(k string) (string, bool) { v, ok := env[k]; return v, ok })
+		var cerr *Error
+		if !errors.As(err, &cerr) || !slices.ContainsFunc(cerr.Problems, func(p Problem) bool { return p.Var == EnvVAPIDPrivateKeyFile }) {
+			t.Errorf("%s: error = %v, want problem for %s", name, err, EnvVAPIDPrivateKeyFile)
+		}
+		if err != nil && (strings.Contains(err.Error(), contents) || strings.Contains(err.Error(), contents[:16])) {
+			t.Errorf("%s: error quotes the private key: %v", name, err)
+		}
+	}
+}
+
 func TestPublicURLWithCredentialsRejected(t *testing.T) {
 	t.Parallel()
 

internal/db/notifications.sql.go

@@ -0,0 +1,202 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.31.1
+// source: notifications.sql
+
+package db
+
+import (
+	"context"
+	"database/sql"
+)
+
+const claimDueNotification = `-- name: ClaimDueNotification :one
+UPDATE notification_outbox
+SET next_attempt_at = ?1, updated_at = ?2
+WHERE id = (
+	SELECT id FROM notification_outbox
+	WHERE status = 'pending' AND next_attempt_at <= ?2
+	ORDER BY next_attempt_at, id
+	LIMIT 1
+)
+RETURNING id, event_key, channel, payload, status, attempts, next_attempt_at, last_error, created_at, updated_at
+`
+
+type ClaimDueNotificationParams struct {
+	LeaseUntil sql.NullString
+	Now        string
+}
+
+// Leases the pending notification due longest ago by moving its
+// next_attempt_at to lease_until, and returns it. A claimed row is not due
+// again until the lease ends, so no other claim takes it while it is being
+// delivered. Returns sql.ErrNoRows when none is due.
+func (q *Queries) ClaimDueNotification(ctx context.Context, arg ClaimDueNotificationParams) (NotificationOutbox, error) {
+	row := q.db.QueryRowContext(ctx, claimDueNotification, arg.LeaseUntil, arg.Now)
+	var i NotificationOutbox
+	err := row.Scan(
+		&i.ID,
+		&i.EventKey,
+		&i.Channel,
+		&i.Payload,
+		&i.Status,
+		&i.Attempts,
+		&i.NextAttemptAt,
+		&i.LastError,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}
+
+const failNotification = `-- name: FailNotification :execrows
+UPDATE notification_outbox
+SET status = 'failed', attempts = attempts + ?1, next_attempt_at = NULL, last_error = ?2, updated_at = ?3
+WHERE id = ?4 AND status = 'pending' AND next_attempt_at = ?5
+`
+
+type FailNotificationParams struct {
+	Attempted  int64
+	LastError  sql.NullString
+	Now        string
+	ID         string
+	LeaseUntil sql.NullString
+}
+
+// Gives up on a notification. attempts counts the delivery attempt that
+// failed, if one was made. The lease must still be the claim's.
+func (q *Queries) FailNotification(ctx context.Context, arg FailNotificationParams) (int64, error) {
+	result, err := q.db.ExecContext(ctx, failNotification,
+		arg.Attempted,
+		arg.LastError,
+		arg.Now,
+		arg.ID,
+		arg.LeaseUntil,
+	)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected()
+}
+
+const getNotificationPref = `-- name: GetNotificationPref :one
+SELECT event, push, chat, created_at, updated_at FROM notification_prefs
+WHERE event = ?
+`
+
+func (q *Queries) GetNotificationPref(ctx context.Context, event string) (NotificationPref, error) {
+	row := q.db.QueryRowContext(ctx, getNotificationPref, event)
+	var i NotificationPref
+	err := row.Scan(
+		&i.Event,
+		&i.Push,
+		&i.Chat,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}
+
+const insertNotification = `-- name: InsertNotification :execrows
+INSERT INTO notification_outbox (
+	id, event_key, channel, payload, status, attempts, next_attempt_at, created_at, updated_at
+) VALUES (
+	?1, ?2, ?3, ?4, 'pending', 0, ?5, ?6, ?6
+)
+ON CONFLICT (event_key, channel) DO NOTHING
+`
+
+type InsertNotificationParams struct {
+	ID            string
+	EventKey      string
+	Channel       string
+	Payload       string
+	NextAttemptAt sql.NullString
+	Now           string
+}
+
+// Stores a pending notification for one channel, due at once. A row already
+// stored for the event key and channel, in any status, is left unchanged and
+// no row is inserted.
+func (q *Queries) InsertNotification(ctx context.Context, arg InsertNotificationParams) (int64, error) {
+	result, err := q.db.ExecContext(ctx, insertNotification,
+		arg.ID,
+		arg.EventKey,
+		arg.Channel,
+		arg.Payload,
+		arg.NextAttemptAt,
+		arg.Now,
+	)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected()
+}
+
+const markNotificationSent = `-- name: MarkNotificationSent :execrows
+UPDATE notification_outbox
+SET status = 'sent', attempts = attempts + 1, next_attempt_at = NULL, updated_at = ?1
+WHERE id = ?2 AND status = 'pending' AND next_attempt_at = ?3
+`
+
+type MarkNotificationSentParams struct {
+	Now        string
+	ID         string
+	LeaseUntil sql.NullString
+}
+
+// Records a delivered notification; updated_at is when it was sent. The
+// lease must still be the claim's.
+func (q *Queries) MarkNotificationSent(ctx context.Context, arg MarkNotificationSentParams) (int64, error) {
+	result, err := q.db.ExecContext(ctx, markNotificationSent, arg.Now, arg.ID, arg.LeaseUntil)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected()
+}
+
+const nextNotificationDue = `-- name: NextNotificationDue :one
+SELECT next_attempt_at FROM notification_outbox
+WHERE status = 'pending'
+ORDER BY next_attempt_at
+LIMIT 1
+`
+
+// Returns when the next pending notification is due. Returns sql.ErrNoRows
+// when none is pending.
+func (q *Queries) NextNotificationDue(ctx context.Context) (sql.NullString, error) {
+	row := q.db.QueryRowContext(ctx, nextNotificationDue)
+	var next_attempt_at sql.NullString
+	err := row.Scan(&next_attempt_at)
+	return next_attempt_at, err
+}
+
+const retryNotification = `-- name: RetryNotification :execrows
+UPDATE notification_outbox
+SET attempts = attempts + 1, next_attempt_at = ?1, last_error = ?2, updated_at = ?3
+WHERE id = ?4 AND status = 'pending' AND next_attempt_at = ?5
+`
+
+type RetryNotificationParams struct {
+	NextAttemptAt sql.NullString
+	LastError     sql.NullString
+	Now           string
+	ID            string
+	LeaseUntil    sql.NullString
+}
+
+// Records a failed delivery and when to try again. The lease must still be
+// the claim's.
+func (q *Queries) RetryNotification(ctx context.Context, arg RetryNotificationParams) (int64, error) {
+	result, err := q.db.ExecContext(ctx, retryNotification,
+		arg.NextAttemptAt,
+		arg.LastError,
+		arg.Now,
+		arg.ID,
+		arg.LeaseUntil,
+	)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected()
+}

internal/db/push_subscriptions.sql.go

@@ -0,0 +1,77 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.31.1
+// source: push_subscriptions.sql
+
+package db
+
+import (
+	"context"
+	"database/sql"
+)
+
+const deletePushSubscription = `-- name: DeletePushSubscription :execrows
+DELETE FROM push_subscriptions
+WHERE endpoint = ?
+`
+
+func (q *Queries) DeletePushSubscription(ctx context.Context, endpoint string) (int64, error) {
+	result, err := q.db.ExecContext(ctx, deletePushSubscription, endpoint)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected()
+}
+
+const upsertPushSubscription = `-- name: UpsertPushSubscription :one
+INSERT INTO push_subscriptions (
+	id, endpoint, p256dh, auth, user_agent, failure_count, created_at, updated_at
+) VALUES (
+	?, ?, ?, ?, ?, 0, ?, ?
+)
+ON CONFLICT (endpoint) DO UPDATE SET
+	p256dh = excluded.p256dh,
+	auth = excluded.auth,
+	user_agent = excluded.user_agent,
+	failure_count = 0,
+	updated_at = excluded.updated_at
+RETURNING id, endpoint, p256dh, auth, user_agent, failure_count, last_success_at, created_at, updated_at
+`
+
+type UpsertPushSubscriptionParams struct {
+	ID        string
+	Endpoint  string
+	P256dh    string
+	Auth      string
+	UserAgent sql.NullString
+	CreatedAt string
+	UpdatedAt string
+}
+
+// Stores a browser's push subscription, keyed by its endpoint. Subscribing
+// an endpoint already stored replaces its keys and user agent and clears
+// its failure count, keeping its id, created_at and last_success_at.
+func (q *Queries) UpsertPushSubscription(ctx context.Context, arg UpsertPushSubscriptionParams) (PushSubscription, error) {
+	row := q.db.QueryRowContext(ctx, upsertPushSubscription,
+		arg.ID,
+		arg.Endpoint,
+		arg.P256dh,
+		arg.Auth,
+		arg.UserAgent,
+		arg.CreatedAt,
+		arg.UpdatedAt,
+	)
+	var i PushSubscription
+	err := row.Scan(
+		&i.ID,
+		&i.Endpoint,
+		&i.P256dh,
+		&i.Auth,
+		&i.UserAgent,
+		&i.FailureCount,
+		&i.LastSuccessAt,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}

internal/db/querier.go

@@ -12,6 +12,11 @@ import (
 type Querier interface {
 	// An unknown id returns sql.ErrNoRows.
 	ArchiveDinner(ctx context.Context, arg ArchiveDinnerParams) (Dinner, error)
+	// Leases the pending notification due longest ago by moving its
+	// next_attempt_at to lease_until, and returns it. A claimed row is not due
+	// again until the lease ends, so no other claim takes it while it is being
+	// delivered. Returns sql.ErrNoRows when none is due.
+	ClaimDueNotification(ctx context.Context, arg ClaimDueNotificationParams) (NotificationOutbox, error)
 	// Marks the oldest queued job running and returns it. Returns sql.ErrNoRows
 	// when no job is queued.
 	ClaimNextJob(ctx context.Context, now sql.NullString) (Job, error)
@@ -62,11 +67,15 @@ type Querier interface {
 	DecideSuggestion(ctx context.Context, arg DecideSuggestionParams) (int64, error)
 	DeleteAIRunsBefore(ctx context.Context, cutoff string) (int64, error)
 	DeleteIntegrationsGoogle(ctx context.Context) error
+	DeletePushSubscription(ctx context.Context, endpoint string) (int64, error)
 	DeleteRecipeIngredients(ctx context.Context, recipeID string) error
 	DeleteRecipeSteps(ctx context.Context, recipeID string) error
 	DeleteShoppingGroup(ctx context.Context, id string) error
 	DeleteShoppingItem(ctx context.Context, id string) error
 	FailJob(ctx context.Context, arg FailJobParams) (int64, error)
+	// Gives up on a notification. attempts counts the delivery attempt that
+	// failed, if one was made. The lease must still be the claim's.
+	FailNotification(ctx context.Context, arg FailNotificationParams) (int64, error)
 	// Fails every unarchived dinner still pending whose grounding job for its
 	// current grounding_revision is no longer queued or running: the process
 	// stopped before the job, or before its handler recorded a result. An
@@ -111,6 +120,7 @@ type Querier interface {
 	// The newest batch, whatever its status. Returns sql.ErrNoRows when there
 	// is none.
 	GetLatestSuggestionBatch(ctx context.Context) (SuggestionBatch, error)
+	GetNotificationPref(ctx context.Context, event string) (NotificationPref, error)
 	// The pending Rotation check of dinner_id. MarkTried makes one only for a
 	// dinner in the Quest log, which it moves to tried, so a dinner has at
 	// most one. Returns sql.ErrNoRows when there is none.
@@ -152,6 +162,10 @@ type Querier interface {
 	// them only when a member edited them while it was grounding. Like
 	// GroundDinner it clears the pasted recipe_url: the recipe replaces the link.
 	GroundPendingDinner(ctx context.Context, arg GroundPendingDinnerParams) (int64, error)
+	// Stores a pending notification for one channel, due at once. A row already
+	// stored for the event key and channel, in any status, is left unchanged and
+	// no row is inserted.
+	InsertNotification(ctx context.Context, arg InsertNotificationParams) (int64, error)
 	// The pending suggestions whose dinner is still suggested, oldest first,
 	// with their dinners.
 	ListDeck(ctx context.Context) ([]ListDeckRow, error)
@@ -210,6 +224,9 @@ type Querier interface {
 	// Moves a dinner still in the Quest log to tried; a dinner with any other
 	// status is left as it is (0 rows).
 	MarkDinnerTried(ctx context.Context, arg MarkDinnerTriedParams) (int64, error)
+	// Records a delivered notification; updated_at is when it was sent. The
+	// lease must still be the claim's.
+	MarkNotificationSent(ctx context.Context, arg MarkNotificationSentParams) (int64, error)
 	// Records an edit of plan id, raising its revision: a synced plan becomes
 	// changed, any other keeps its status.
 	MarkWeekPlanEdited(ctx context.Context, arg MarkWeekPlanEditedParams) error
@@ -229,6 +246,9 @@ type Querier interface {
 	// by a Rotation check decision, recording updated_by; its origin is kept.
 	// A dinner no longer tried is left as it is (0 rows).
 	MoveTriedDinner(ctx context.Context, arg MoveTriedDinnerParams) (int64, error)
+	// Returns when the next pending notification is due. Returns sql.ErrNoRows
+	// when none is pending.
+	NextNotificationDue(ctx context.Context) (sql.NullString, error)
 	// Stores a partial result of a running job.
 	PublishJobResult(ctx context.Context, arg PublishJobResultParams) (int64, error)
 	// Plans dinner_id on date of plan_id. An existing day keeps its calendar
@@ -240,6 +260,9 @@ type Querier interface {
 	RedraftWeekPlan(ctx context.Context, arg RedraftWeekPlanParams) error
 	// Records a generation of list id from plan plan_id.
 	RegenerateShoppingList(ctx context.Context, arg RegenerateShoppingListParams) error
+	// Records a failed delivery and when to try again. The lease must still be
+	// the claim's.
+	RetryNotification(ctx context.Context, arg RetryNotificationParams) (int64, error)
 	// An unknown id returns sql.ErrNoRows.
 	SetDinnerFavorite(ctx context.Context, arg SetDinnerFavoriteParams) (Dinner, error)
 	// Sets the chosen calendar; affects no row when nothing is connected.
@@ -276,6 +299,10 @@ type Querier interface {
 	// Creates the single row (id 1) or replaces every column except id and
 	// created_at.
 	UpsertIntegrationsGoogle(ctx context.Context, arg UpsertIntegrationsGoogleParams) (IntegrationsGoogle, error)
+	// Stores a browser's push subscription, keyed by its endpoint. Subscribing
+	// an endpoint already stored replaces its keys and user agent and clears
+	// its failure count, keeping its id, created_at and last_success_at.
+	UpsertPushSubscription(ctx context.Context, arg UpsertPushSubscriptionParams) (PushSubscription, error)
 	// A recipe is keyed by source_url: re-fetching the same URL updates the
 	// existing row and keeps its id and created_at, which the returned row
 	// carries. Replace its ingredients and steps in the same transaction with

internal/notify/notify.go

@@ -0,0 +1,248 @@
+// Package notify decides who is told what and delivers it reliably. It is
+// the only package that reads notification_prefs to choose channels.
+//
+// Emit is the one way to notify the household: it reads the preference row
+// of the event's type and, for each channel switched on, stores one pending
+// row in notification_outbox keyed by (event key, channel). The event key is
+// the caller's idempotency key, so emitting the same event twice stores
+// nothing the second time and never touches a row already stored, whatever
+// its status.
+//
+// The worker started by Start delivers due rows through the Sender
+// 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.
+package notify
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"log/slog"
+	"net/url"
+	"strings"
+	"sync"
+	"time"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/db"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
+)
+
+// EventType is what a notification is about. Each has one row in
+// notification_prefs saying which channels it goes to.
+type EventType string
+
+// The event types, as notification_prefs.event names them.
+const (
+	PlanReady      EventType = "plan_ready"
+	ListReady      EventType = "list_ready"
+	DayOfReminder  EventType = "day_of_reminder"
+	NewSuggestions EventType = "new_suggestions"
+	RotationReview EventType = "rotation_review"
+)
+
+// eventTypes is every EventType.
+var eventTypes = map[EventType]bool{
+	PlanReady: true, ListReady: true, DayOfReminder: true, NewSuggestions: true, RotationReview: true,
+}
+
+// Channel is a way of telling the household, as notification_outbox.channel
+// names it.
+type Channel string
+
+// The channels.
+const (
+	ChannelPush Channel = "push"
+	ChannelChat Channel = "chat"
+)
+
+// Event is something to tell the household.
+type Event struct {
+	// Type is what the event is about.
+	Type EventType
+	// Key identifies this event: it starts with Type and a colon, as in
+	// "plan_ready:2026-10-12". An event emitted again with the same key is
+	// ignored.
+	Key string
+	// Title is the notification's headline; it must not be blank.
+	Title string
+	// Body is the notification's text; it may be empty.
+	Body string
+	// URL is the path-absolute, same-origin path a tap on the notification
+	// opens, such as "/plan".
+	URL string
+	// Week is the Monday of the week the event concerns, for the senders'
+	// message builders; zero when the event concerns no week.
+	Week store.LocalDate
+}
+
+// Payload is the JSON stored in notification_outbox.payload and handed to
+// a Sender: the one shape every channel delivers from. Its title, body, tag
+// and url are the notice the service worker shows (web/src/push/notification.ts),
+// which ignores the other fields.
+type Payload struct {
+	Event EventType `json:"event"`
+	Title string    `json:"title"`
+	Body  string    `json:"body"`
+	// URL is a path-absolute, same-origin path. A sender that needs an
+	// absolute URL resolves it against the public URL.
+	URL string `json:"url"`
+	// Tag is the event key, so a notification shown again for the same
+	// event replaces the first.
+	Tag string `json:"tag"`
+	// Week is the YYYY-MM-DD Monday of the event's week, or absent.
+	Week string `json:"week,omitempty"`
+}
+
+// ErrInvalidEvent is returned by Emit for an event it refuses; nothing is
+// stored.
+var ErrInvalidEvent = errors.New("notify: invalid event")
+
+// Service emits notifications and runs the worker that delivers them.
+type Service struct {
+	st     *store.Store
+	logger *slog.Logger
+	// now is the clock rows are created, claimed and retried on; tests
+	// replace it.
+	now func() time.Time
+	// wake holds up to one token; Emit adds one so the worker looks for
+	// the rows it stored.
+	wake chan struct{}
+
+	mu      sync.Mutex
+	senders map[Channel]Sender
+	started bool
+
+	wg sync.WaitGroup
+}
+
+// NewService returns a service over st with no senders registered.
+func NewService(st *store.Store, logger *slog.Logger) (*Service, error) {
+	if st == nil {
+		return nil, errors.New("notify: nil store")
+	}
+	if logger == nil {
+		return nil, errors.New("notify: nil logger")
+	}
+	return &Service{
+		st:      st,
+		logger:  logger,
+		now:     time.Now,
+		wake:    make(chan struct{}, 1),
+		senders: make(map[Channel]Sender),
+	}, nil
+}
+
+// Emit stores one pending notification of ev for each channel its type's
+// preference switches on, and wakes the worker. A channel already holding a
+// row with ev.Key is left as it is. An invalid event is ErrInvalidEvent and
+// stores nothing; a type with no preference row is an error.
+func (s *Service) Emit(ctx context.Context, ev Event) error {
+	if err := validate(ev); err != nil {
+		return err
+	}
+	payload := Payload{Event: ev.Type, Title: ev.Title, Body: ev.Body, URL: ev.URL, Tag: ev.Key}
+	if !ev.Week.IsZero() {
+		payload.Week = ev.Week.String()
+	}
+	data, err := json.Marshal(payload)
+	if err != nil {
+		return fmt.Errorf("notify: encode payload of %s: %w", ev.Key, err)
+	}
+
+	var queued []Channel
+	err = s.st.WithTx(ctx, func(tx *sql.Tx) error {
+		q := db.New(tx)
+		pref, err := q.GetNotificationPref(ctx, string(ev.Type))
+		if errors.Is(err, sql.ErrNoRows) {
+			return fmt.Errorf("notify: no notification preference for %s", ev.Type)
+		}
+		if err != nil {
+			return fmt.Errorf("notify: read notification preference for %s: %w", ev.Type, err)
+		}
+		now := timestamp(s.now())
+		for _, ch := range enabledChannels(pref) {
+			n, err := q.InsertNotification(ctx, db.InsertNotificationParams{
+				ID:            store.NewID(),
+				EventKey:      ev.Key,
+				Channel:       string(ch),
+				Payload:       string(data),
+				NextAttemptAt: sql.NullString{String: now, Valid: true},
+				Now:           now,
+			})
+			if err != nil {
+				return fmt.Errorf("notify: store %s notification %s: %w", ch, ev.Key, err)
+			}
+			if n == 1 {
+				queued = append(queued, ch)
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+	s.logger.InfoContext(ctx, "notification emitted", "event_key", ev.Key, "queued", queued)
+	if len(queued) > 0 {
+		s.wakeWorker()
+	}
+	return nil
+}
+
+// enabledChannels returns the channels pref switches on.
+func enabledChannels(pref db.NotificationPref) []Channel {
+	var chs []Channel
+	if pref.Push == 1 {
+		chs = append(chs, ChannelPush)
+	}
+	if pref.Chat == 1 {
+		chs = append(chs, ChannelChat)
+	}
+	return chs
+}
+
+// validate reports why ev cannot be emitted, wrapping ErrInvalidEvent.
+func validate(ev Event) error {
+	if !eventTypes[ev.Type] {
+		return fmt.Errorf("%w: unknown type %q", ErrInvalidEvent, ev.Type)
+	}
+	prefix := string(ev.Type) + ":"
+	if !strings.HasPrefix(ev.Key, prefix) || len(ev.Key) == len(prefix) {
+		return fmt.Errorf("%w: key %q does not start with %q and an identifier", ErrInvalidEvent, ev.Key, prefix)
+	}
+	if strings.TrimSpace(ev.Title) == "" {
+		return fmt.Errorf("%w: %s has a blank title", ErrInvalidEvent, ev.Key)
+	}
+	if !isAppPath(ev.URL) {
+		return fmt.Errorf("%w: %s url %q is not a path-absolute same-origin path", ErrInvalidEvent, ev.Key, ev.URL)
+	}
+	return nil
+}
+
+// isAppPath reports whether raw is a path on the app's own origin, as the
+// service worker requires: it starts with one slash and names no scheme or
+// host, however it is parsed.
+func isAppPath(raw string) bool {
+	if !strings.HasPrefix(raw, "/") || strings.HasPrefix(raw, "//") || strings.ContainsAny(raw, "\\\t\r\n") {
+		return false
+	}
+	u, err := url.Parse(raw)
+	return err == nil && u.Scheme == "" && u.Host == "" && !strings.HasPrefix(u.Path, "//")
+}
+
+// timestamp returns t in the stored UTC RFC 3339 form.
+func timestamp(t time.Time) string {
+	return store.Timestamp{Time: t.UTC().Truncate(time.Millisecond)}.String()
+}
+
+// parseTimestamp parses a stored timestamp.
+func parseTimestamp(s string) (time.Time, error) {
+	var ts store.Timestamp
+	if err := ts.Scan(s); err != nil {
+		return time.Time{}, err
+	}
+	return ts.Time, nil
+}

internal/notify/notify_test.go

@@ -0,0 +1,730 @@
+package notify
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"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/store"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/migrations"
+)
+
+// start is the fake clock's first instant.
+var start = time.Date(2026, 10, 9, 15, 0, 0, 0, time.UTC)
+
+// clock is a controllable clock.
+type clock struct {
+	mu sync.Mutex
+	t  time.Time
+}
+
+func (c *clock) now() time.Time {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.t
+}
+
+func (c *clock) set(t time.Time) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.t = t
+}
+
+// fakeSender records the messages it is given and fails while fail is set.
+type fakeSender struct {
+	mu   sync.Mutex
+	fail error
+	got  []Message
+}
+
+func (f *fakeSender) Send(_ context.Context, m Message) error {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.got = append(f.got, m)
+	return f.fail
+}
+
+func (f *fakeSender) messages() []Message {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	return append([]Message(nil), f.got...)
+}
+
+func newTestService(t *testing.T) (*Service, *store.Store, *clock) {
+	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)
+	}
+	if err := household.SeedNotificationPrefs(ctx, st); err != nil {
+		t.Fatal(err)
+	}
+	svc, err := NewService(st, slog.New(slog.NewTextHandler(io.Discard, nil)))
+	if err != nil {
+		t.Fatal(err)
+	}
+	c := &clock{t: start}
+	svc.now = c.now
+	return svc, st, c
+}
+
+func setPref(t *testing.T, st *store.Store, ev EventType, push, chat bool) {
+	t.Helper()
+	res, err := st.Writer.Exec(`UPDATE notification_prefs SET push = ?, chat = ? WHERE event = ?`, push, chat, string(ev))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if n, _ := res.RowsAffected(); n != 1 {
+		t.Fatalf("no notification preference for %s", ev)
+	}
+}
+
+// outbox returns the stored rows of key by channel.
+func outbox(t *testing.T, st *store.Store, key string) map[Channel]db.NotificationOutbox {
+	t.Helper()
+	rs, err := st.Reader.Query(`SELECT id, event_key, channel, payload, status, attempts, next_attempt_at, last_error, created_at, updated_at
+		FROM notification_outbox WHERE event_key = ?`, key)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer rs.Close()
+	got := map[Channel]db.NotificationOutbox{}
+	for rs.Next() {
+		var r db.NotificationOutbox
+		if err := rs.Scan(&r.ID, &r.EventKey, &r.Channel, &r.Payload, &r.Status, &r.Attempts, &r.NextAttemptAt, &r.LastError, &r.CreatedAt, &r.UpdatedAt); err != nil {
+			t.Fatal(err)
+		}
+		if _, dup := got[Channel(r.Channel)]; dup {
+			t.Fatalf("two %s rows for %s", r.Channel, key)
+		}
+		got[Channel(r.Channel)] = r
+	}
+	if err := rs.Err(); err != nil {
+		t.Fatal(err)
+	}
+	return got
+}
+
+func onlyRow(t *testing.T, st *store.Store, key string, ch Channel) db.NotificationOutbox {
+	t.Helper()
+	rows := outbox(t, st, key)
+	r, ok := rows[ch]
+	if !ok || len(rows) != 1 {
+		t.Fatalf("rows of %s = %v, want one %s row", key, rows, ch)
+	}
+	return r
+}
+
+func planReady(key string) Event {
+	return Event{
+		Type:  PlanReady,
+		Key:   key,
+		Title: "This week's plan is ready",
+		Body:  "Five dinners on the Draft board.",
+		URL:   "/plan",
+		Week:  mustDate("2026-10-12"),
+	}
+}
+
+func mustDate(s string) store.LocalDate {
+	d, err := store.ParseLocalDate(s)
+	if err != nil {
+		panic(err)
+	}
+	return d
+}
+
+func TestEmitRespectsPrefsMatrix(t *testing.T) {
+	ctx := context.Background()
+	for _, tc := range []struct {
+		push, chat bool
+		want       []Channel
+	}{
+		{push: false, chat: false, want: nil},
+		{push: true, chat: false, want: []Channel{ChannelPush}},
+		{push: false, chat: true, want: []Channel{ChannelChat}},
+		{push: true, chat: true, want: []Channel{ChannelPush, ChannelChat}},
+	} {
+		t.Run(fmt.Sprintf("push=%v,chat=%v", tc.push, tc.chat), func(t *testing.T) {
+			svc, st, _ := newTestService(t)
+			for ev := range eventTypes {
+				setPref(t, st, ev, tc.push, tc.chat)
+				key := string(ev) + ":2026-10-12"
+				if err := svc.Emit(ctx, Event{Type: ev, Key: key, Title: "Title", Body: "Body", URL: "/"}); err != nil {
+					t.Fatal(err)
+				}
+				rows := outbox(t, st, key)
+				if len(rows) != len(tc.want) {
+					t.Fatalf("%s: %d rows, want channels %v", ev, len(rows), tc.want)
+				}
+				for _, ch := range tc.want {
+					r, ok := rows[ch]
+					if !ok {
+						t.Fatalf("%s: no %s row", ev, ch)
+					}
+					now := timestamp(start)
+					if r.Status != "pending" || r.Attempts != 0 || r.NextAttemptAt.String != now || r.CreatedAt != now || r.LastError.Valid {
+						t.Errorf("%s %s row = %+v, want pending, due now", ev, ch, r)
+					}
+				}
+			}
+		})
+	}
+}
+
+func TestEmitStoresPayload(t *testing.T) {
+	svc, st, _ := newTestService(t)
+	setPref(t, st, PlanReady, true, true)
+	if err := svc.Emit(context.Background(), planReady("plan_ready:2026-10-12")); err != nil {
+		t.Fatal(err)
+	}
+	want := `{"event":"plan_ready","title":"This week's plan is ready","body":"Five dinners on the Draft board.","url":"/plan","tag":"plan_ready:2026-10-12","week":"2026-10-12"}`
+	for ch, r := range outbox(t, st, "plan_ready:2026-10-12") {
+		if r.Payload != want {
+			t.Errorf("%s payload = %s, want %s", ch, r.Payload, want)
+		}
+	}
+
+	// An event about no week omits it.
+	if err := svc.Emit(context.Background(), Event{Type: NewSuggestions, Key: "new_suggestions:batch1", Title: "New Side quests", URL: "/suggestions"}); err != nil {
+		t.Fatal(err)
+	}
+	r := onlyRow(t, st, "new_suggestions:batch1", ChannelPush)
+	if want := `{"event":"new_suggestions","title":"New Side quests","body":"","url":"/suggestions","tag":"new_suggestions:batch1"}`; r.Payload != want {
+		t.Errorf("payload = %s, want %s", r.Payload, want)
+	}
+}
+
+func TestEmitIgnoresDuplicateKey(t *testing.T) {
+	ctx := context.Background()
+	svc, st, c := newTestService(t)
+	setPref(t, st, PlanReady, true, false)
+	const key = "plan_ready:2026-10-12"
+	if err := svc.Emit(ctx, planReady(key)); err != nil {
+		t.Fatal(err)
+	}
+	first := onlyRow(t, st, key, ChannelPush)
+
+	c.set(start.Add(time.Minute))
+	again := planReady(key)
+	again.Title = "A different title"
+	if err := svc.Emit(ctx, again); err != nil {
+		t.Fatalf("duplicate emit: %v", err)
+	}
+	if got := onlyRow(t, st, key, ChannelPush); got != first {
+		t.Fatalf("duplicate emit changed the row:\n got %+v\nwant %+v", got, first)
+	}
+
+	// Once sent, a duplicate still leaves the row as it is.
+	sender := &fakeSender{}
+	if err := svc.Register(ChannelPush, sender); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := svc.deliverDue(ctx); err != nil {
+		t.Fatal(err)
+	}
+	sent := onlyRow(t, st, key, ChannelPush)
+	if sent.Status != "sent" {
+		t.Fatalf("status = %s, want sent", sent.Status)
+	}
+	c.set(start.Add(2 * time.Minute))
+	if err := svc.Emit(ctx, again); err != nil {
+		t.Fatalf("emit after sent: %v", err)
+	}
+	if got := onlyRow(t, st, key, ChannelPush); got != sent {
+		t.Fatalf("emit after sent changed the row:\n got %+v\nwant %+v", got, sent)
+	}
+	if _, err := svc.deliverDue(ctx); err != nil {
+		t.Fatal(err)
+	}
+	if n := len(sender.messages()); n != 1 {
+		t.Fatalf("%d deliveries, want 1", n)
+	}
+}
+
+func TestEmitRejectsInvalidEvents(t *testing.T) {
+	svc, st, _ := newTestService(t)
+	valid := planReady("plan_ready:2026-10-12")
+	for name, mutate := range map[string]func(*Event){
+		"unknown type":         func(e *Event) { e.Type = "dinner_burnt" },
+		"empty key":            func(e *Event) { e.Key = "" },
+		"key without id":       func(e *Event) { e.Key = "plan_ready:" },
+		"key of another type":  func(e *Event) { e.Key = "list_ready:2026-10-12" },
+		"blank title":          func(e *Event) { e.Title = "  " },
+		"empty url":            func(e *Event) { e.URL = "" },
+		"relative url":         func(e *Event) { e.URL = "plan" },
+		"absolute url":         func(e *Event) { e.URL = "https://evil.example/plan" },
+		"protocol-relative":    func(e *Event) { e.URL = "//evil.example/plan" },
+		"backslash url":        func(e *Event) { e.URL = "/\\evil.example" },
+		"url with a tab":       func(e *Event) { e.URL = "/\t/evil.example" },
+		"url with a bad query": func(e *Event) { e.URL = "/plan%zz" },
+	} {
+		t.Run(name, func(t *testing.T) {
+			ev := valid
+			mutate(&ev)
+			if err := svc.Emit(context.Background(), ev); !errors.Is(err, ErrInvalidEvent) {
+				t.Fatalf("Emit = %v, want ErrInvalidEvent", err)
+			}
+		})
+	}
+	var n int
+	if err := st.Reader.QueryRow(`SELECT COUNT(*) FROM notification_outbox`).Scan(&n); err != nil {
+		t.Fatal(err)
+	}
+	if n != 0 {
+		t.Fatalf("%d rows stored, want 0", n)
+	}
+}
+
+func TestEmitWithoutPrefIsAnError(t *testing.T) {
+	svc, st, _ := newTestService(t)
+	if _, err := st.Writer.Exec(`DELETE FROM notification_prefs WHERE event = 'plan_ready'`); err != nil {
+		t.Fatal(err)
+	}
+	err := svc.Emit(context.Background(), planReady("plan_ready:2026-10-12"))
+	if err == nil || errors.Is(err, ErrInvalidEvent) {
+		t.Fatalf("Emit = %v, want a missing-preference error", err)
+	}
+}
+
+func TestDeliveryMarkedSent(t *testing.T) {
+	ctx := context.Background()
+	svc, st, c := newTestService(t)
+	setPref(t, st, PlanReady, true, true)
+	push, chat := &fakeSender{}, &fakeSender{}
+	if err := svc.Register(ChannelPush, push); err != nil {
+		t.Fatal(err)
+	}
+	if err := svc.Register(ChannelChat, chat); err != nil {
+		t.Fatal(err)
+	}
+	const key = "plan_ready:2026-10-12"
+	if err := svc.Emit(ctx, planReady(key)); err != nil {
+		t.Fatal(err)
+	}
+	sentAt := start.Add(3 * time.Second)
+	c.set(sentAt)
+	wait, err := svc.deliverDue(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if wait != -1 {
+		t.Errorf("wait = %v, want -1 with nothing pending", wait)
+	}
+
+	rows := outbox(t, st, key)
+	wantPayload := Payload{Event: PlanReady, Title: "This week's plan is ready", Body: "Five dinners on the Draft board.", URL: "/plan", Tag: key, Week: "2026-10-12"}
+	for ch, sender := range map[Channel]*fakeSender{ChannelPush: push, ChannelChat: chat} {
+		r := rows[ch]
+		if r.Status != "sent" || r.Attempts != 1 || r.NextAttemptAt.Valid || r.UpdatedAt != timestamp(sentAt) || r.LastError.Valid {
+			t.Errorf("%s row = %+v, want sent at %s after 1 attempt", ch, r, timestamp(sentAt))
+		}
+		got := sender.messages()
+		want := Message{ID: r.ID, EventKey: key, Channel: ch, Payload: wantPayload, Attempt: 1}
+		if len(got) != 1 || got[0] != want {
+			t.Errorf("%s sender got %+v, want [%+v]", ch, got, want)
+		}
+	}
+}
+
+func TestRetryBackoffSchedule(t *testing.T) {
+	ctx := context.Background()
+	svc, st, c := newTestService(t)
+	setPref(t, st, PlanReady, true, false)
+	sender := &fakeSender{fail: errors.New("push service unavailable")}
+	if err := svc.Register(ChannelPush, 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)
+	}
+
+	now := start
+	for i, wantDelay := range []time.Duration{
+		time.Minute, 2 * time.Minute, 4 * time.Minute, 8 * time.Minute, 16 * time.Minute,
+		32 * time.Minute, time.Hour, time.Hour, time.Hour,
+	} {
+		c.set(now)
+		wait, err := svc.deliverDue(ctx)
+		if err != nil {
+			t.Fatal(err)
+		}
+		r := onlyRow(t, st, key, ChannelPush)
+		wantNext := now.Add(wantDelay)
+		if r.Status != "pending" || r.Attempts != int64(i+1) || r.NextAttemptAt.String != timestamp(wantNext) ||
+			r.LastError.String != "push service unavailable" {
+			t.Fatalf("after failure %d row = %+v, want pending, attempts %d, next %s", i+1, r, i+1, timestamp(wantNext))
+		}
+		if wait != wantDelay {
+			t.Fatalf("after failure %d wait = %v, want %v", i+1, wait, wantDelay)
+		}
+
+		// Not due a moment before the retry time.
+		c.set(wantNext.Add(-time.Millisecond))
+		if _, err := svc.deliverDue(ctx); err != nil {
+			t.Fatal(err)
+		}
+		if n := len(sender.messages()); n != i+1 {
+			t.Fatalf("%d deliveries before the retry was due, want %d", n, i+1)
+		}
+		now = wantNext
+	}
+	for i, m := range sender.messages() {
+		if m.Attempt != int64(i+1) {
+			t.Errorf("delivery %d has Attempt %d", i+1, m.Attempt)
+		}
+	}
+}
+
+func TestRetryThenSent(t *testing.T) {
+	ctx := context.Background()
+	svc, st, c := newTestService(t)
+	setPref(t, st, ListReady, false, true)
+	sender := &fakeSender{fail: errors.New("chat returned 503")}
+	if err := svc.Register(ChannelChat, sender); err != nil {
+		t.Fatal(err)
+	}
+	const key = "list_ready:2026-10-12"
+	if err := svc.Emit(ctx, Event{Type: ListReady, Key: key, Title: "Supply run ready", URL: "/supply-run"}); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := svc.deliverDue(ctx); err != nil {
+		t.Fatal(err)
+	}
+	sender.mu.Lock()
+	sender.fail = nil
+	sender.mu.Unlock()
+	c.set(start.Add(time.Minute))
+	if _, err := svc.deliverDue(ctx); err != nil {
+		t.Fatal(err)
+	}
+	r := onlyRow(t, st, key, ChannelChat)
+	if r.Status != "sent" || r.Attempts != 2 || r.UpdatedAt != timestamp(start.Add(time.Minute)) {
+		t.Fatalf("row = %+v, want sent on attempt 2", r)
+	}
+}
+
+func TestGiveUpAfter24Hours(t *testing.T) {
+	ctx := context.Background()
+	svc, st, c := newTestService(t)
+	setPref(t, st, DayOfReminder, true, false)
+	sender := &fakeSender{fail: errors.New("push service unavailable")}
+	if err := svc.Register(ChannelPush, sender); err != nil {
+		t.Fatal(err)
+	}
+	const key = "day_of_reminder:2026-10-09"
+	if err := svc.Emit(ctx, Event{Type: DayOfReminder, Key: key, Title: "Tonight: tacos", URL: "/"}); err != nil {
+		t.Fatal(err)
+	}
+
+	// Deliver each retry as it falls due until the row leaves pending.
+	deadline := start.Add(24 * time.Hour)
+	var times []time.Time
+	for range 100 {
+		r := onlyRow(t, st, key, ChannelPush)
+		if r.Status != "pending" {
+			break
+		}
+		due, err := parseTimestamp(r.NextAttemptAt.String)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if due.After(deadline) {
+			t.Fatalf("retry due %s, after the 24 h deadline %s", due, deadline)
+		}
+		c.set(due)
+		times = append(times, due)
+		if _, err := svc.deliverDue(ctx); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	// Attempts at 0, 1, 3, 7, 15, 31 and 63 minutes, then hourly to 1383
+	// minutes (22 more): 29 in all. The row is due once more at the
+	// deadline, where it is failed without being sent.
+	const wantAttempts = 29
+	r := onlyRow(t, st, key, ChannelPush)
+	if r.Status != "failed" || r.Attempts != wantAttempts || r.NextAttemptAt.Valid ||
+		r.LastError.String != "not delivered within 24 hours of creation; last error: push service unavailable" ||
+		r.UpdatedAt != timestamp(deadline) {
+		t.Fatalf("row = %+v, want failed at %s after %d attempts", r, timestamp(deadline), wantAttempts)
+	}
+	if len(times) != wantAttempts+1 || !times[len(times)-1].Equal(deadline) || !times[len(times)-2].Equal(start.Add(1383*time.Minute)) {
+		t.Fatalf("due at %v, want %d attempts ending 1383 min after creation, then the deadline", times, wantAttempts)
+	}
+	if n := len(sender.messages()); n != wantAttempts {
+		t.Fatalf("%d deliveries, want %d", n, wantAttempts)
+	}
+
+	// A failed row is never delivered again.
+	c.set(deadline.Add(48 * time.Hour))
+	if _, err := svc.deliverDue(ctx); err != nil {
+		t.Fatal(err)
+	}
+	if n := len(sender.messages()); n != wantAttempts {
+		t.Fatalf("%d deliveries, want %d", n, wantAttempts)
+	}
+}
+
+// TestOverdueRowIsNeverDelivered covers a row first claimed 24 hours or
+// more after its creation, as when the service was down: it is failed
+// without calling the sender, whether the sender would succeed or fail.
+func TestOverdueRowIsNeverDelivered(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		at   time.Duration
+		fail error
+	}{
+		{"succeeding sender at 24 h", 24 * time.Hour, nil},
+		{"succeeding sender after 24 h", 25 * time.Hour, nil},
+		{"failing sender at 24 h", 24 * time.Hour, errors.New("gone")},
+		{"failing sender after 24 h", 25 * time.Hour, errors.New("gone")},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			ctx := context.Background()
+			svc, st, c := newTestService(t)
+			setPref(t, st, PlanReady, true, false)
+			sender := &fakeSender{fail: tc.fail}
+			if err := svc.Register(ChannelPush, 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)
+			}
+			c.set(start.Add(tc.at))
+			if _, err := svc.deliverDue(ctx); err != nil {
+				t.Fatal(err)
+			}
+			if n := len(sender.messages()); n != 0 {
+				t.Fatalf("%d deliveries of an overdue row, want 0", n)
+			}
+			r := onlyRow(t, st, key, ChannelPush)
+			if r.Status != "failed" || r.Attempts != 0 || r.NextAttemptAt.Valid ||
+				r.LastError.String != "not delivered within 24 hours of creation" || r.UpdatedAt != timestamp(start.Add(tc.at)) {
+				t.Fatalf("row = %+v, want failed without an attempt", r)
+			}
+		})
+	}
+}
+
+// TestRowJustBeforeDeadlineIsDelivered pins the boundary from the other
+// side: a row claimed just under 24 hours after its creation is sent.
+func TestRowJustBeforeDeadlineIsDelivered(t *testing.T) {
+	ctx := context.Background()
+	svc, st, c := newTestService(t)
+	setPref(t, st, PlanReady, true, false)
+	sender := &fakeSender{}
+	if err := svc.Register(ChannelPush, 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)
+	}
+	c.set(start.Add(24*time.Hour - time.Millisecond))
+	if _, err := svc.deliverDue(ctx); err != nil {
+		t.Fatal(err)
+	}
+	if r := onlyRow(t, st, key, ChannelPush); r.Status != "sent" || r.Attempts != 1 || len(sender.messages()) != 1 {
+		t.Fatalf("row = %+v after %d deliveries, want sent once", r, len(sender.messages()))
+	}
+}
+
+func TestChannelWithoutSenderFails(t *testing.T) {
+	ctx := context.Background()
+	svc, st, _ := newTestService(t)
+	setPref(t, st, PlanReady, true, true)
+	push := &fakeSender{}
+	if err := svc.Register(ChannelPush, push); err != nil {
+		t.Fatal(err)
+	}
+	const key = "plan_ready:2026-10-12"
+	if err := svc.Emit(ctx, planReady(key)); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := svc.deliverDue(ctx); err != nil {
+		t.Fatal(err)
+	}
+	rows := outbox(t, st, key)
+	if r := rows[ChannelChat]; r.Status != "failed" || r.Attempts != 0 || r.LastError.String != "no sender registered for channel chat" {
+		t.Fatalf("chat row = %+v, want failed with no sender", r)
+	}
+	if r := rows[ChannelPush]; r.Status != "sent" {
+		t.Fatalf("push row = %+v, want sent", r)
+	}
+}
+
+func TestLeasedRowIsNotClaimedAgain(t *testing.T) {
+	ctx := context.Background()
+	svc, st, c := newTestService(t)
+	setPref(t, st, PlanReady, true, false)
+	sender := &fakeSender{}
+	if err := svc.Register(ChannelPush, 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)
+	}
+	// Another tick claims the row and stops before recording the delivery.
+	lease := start.Add(leaseFor)
+	if _, err := db.New(st.Writer).ClaimDueNotification(ctx, db.ClaimDueNotificationParams{
+		LeaseUntil: sql.NullString{String: timestamp(lease), Valid: true}, Now: timestamp(start),
+	}); err != nil {
+		t.Fatal(err)
+	}
+	c.set(lease.Add(-time.Millisecond))
+	if _, err := svc.deliverDue(ctx); err != nil {
+		t.Fatal(err)
+	}
+	if n := len(sender.messages()); n != 0 {
+		t.Fatalf("%d deliveries of a leased row, want 0", n)
+	}
+	// Once the lease ends the row is delivered.
+	c.set(lease)
+	if _, err := svc.deliverDue(ctx); err != nil {
+		t.Fatal(err)
+	}
+	if r := onlyRow(t, st, key, ChannelPush); r.Status != "sent" || r.Attempts != 1 || len(sender.messages()) != 1 {
+		t.Fatalf("row = %+v after %d deliveries, want sent once", r, len(sender.messages()))
+	}
+}
+
+// blockingSender holds every Send until release is closed.
+type blockingSender struct {
+	fakeSender
+	entered chan struct{}
+	release chan struct{}
+}
+
+func (b *blockingSender) Send(ctx context.Context, m Message) error {
+	b.entered <- struct{}{}
+	<-b.release
+	return b.fakeSender.Send(ctx, m)
+}
+
+func TestConcurrentTicksDeliverOnce(t *testing.T) {
+	ctx := context.Background()
+	svc, st, _ := newTestService(t)
+	setPref(t, st, PlanReady, true, false)
+	sender := &blockingSender{entered: make(chan struct{}, 10), release: make(chan struct{})}
+	if err := svc.Register(ChannelPush, 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)
+	}
+
+	var wg sync.WaitGroup
+	first := make(chan error, 1)
+	wg.Go(func() {
+		_, err := svc.deliverDue(ctx)
+		first <- err
+	})
+	<-sender.entered // the first tick holds the row
+	if _, err := svc.deliverDue(ctx); err != nil {
+		t.Fatal(err)
+	}
+	close(sender.release)
+	wg.Wait()
+	if err := <-first; err != nil {
+		t.Fatal(err)
+	}
+	if n := len(sender.messages()); n != 1 {
+		t.Fatalf("%d deliveries, want 1", n)
+	}
+	if r := onlyRow(t, st, key, ChannelPush); r.Status != "sent" {
+		t.Fatalf("row = %+v, want sent", r)
+	}
+}
+
+func TestRetryDelay(t *testing.T) {
+	for attempt, want := range map[int64]time.Duration{
+		1: time.Minute, 2: 2 * time.Minute, 3: 4 * time.Minute, 6: 32 * time.Minute,
+		7: time.Hour, 8: time.Hour, 1000: time.Hour,
+	} {
+		if got := retryDelay(attempt); got != want {
+			t.Errorf("retryDelay(%d) = %v, want %v", attempt, got, want)
+		}
+	}
+}
+
+func TestRegister(t *testing.T) {
+	svc, _, _ := newTestService(t)
+	if err := svc.Register("email", &fakeSender{}); err == nil {
+		t.Error("registered an unknown channel")
+	}
+	if err := svc.Register(ChannelPush, nil); err == nil {
+		t.Error("registered a nil sender")
+	}
+	if err := svc.Register(ChannelPush, &fakeSender{}); err != nil {
+		t.Fatal(err)
+	}
+	if err := svc.Register(ChannelPush, &fakeSender{}); err == nil {
+		t.Error("registered a second push sender")
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	if err := svc.Start(ctx); err != nil {
+		t.Fatal(err)
+	}
+	if err := svc.Register(ChannelChat, &fakeSender{}); err == nil {
+		t.Error("registered a sender after Start")
+	}
+	if err := svc.Start(ctx); err == nil {
+		t.Error("started twice")
+	}
+	cancel()
+	svc.Wait()
+}
+
+// TestWorkerDeliversEmittedEvent runs the worker on the real clock: Emit
+// wakes it, it delivers, and it stops when its context is cancelled.
+func TestWorkerDeliversEmittedEvent(t *testing.T) {
+	svc, st, _ := newTestService(t)
+	svc.now = time.Now
+	setPref(t, st, PlanReady, true, false)
+	sender := &fakeSender{}
+	if err := svc.Register(ChannelPush, sender); err != nil {
+		t.Fatal(err)
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	if err := svc.Start(ctx); err != nil {
+		t.Fatal(err)
+	}
+	const key = "plan_ready:2026-10-12"
+	if err := svc.Emit(context.Background(), planReady(key)); err != nil {
+		t.Fatal(err)
+	}
+	deadline := time.Now().Add(5 * time.Second)
+	for onlyRow(t, st, key, ChannelPush).Status != "sent" {
+		if time.Now().After(deadline) {
+			t.Fatal("worker did not deliver the notification")
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+	cancel()
+	svc.Wait()
+	if n := len(sender.messages()); n != 1 {
+		t.Fatalf("%d deliveries, want 1", n)
+	}
+}

internal/notify/worker.go

@@ -0,0 +1,299 @@
+package notify
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"log/slog"
+	"time"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/db"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/jobs"
+)
+
+// Delivery timing.
+const (
+	// retryFirst is the wait after a row's first failed delivery; each
+	// further failure doubles it, up to retryMax.
+	retryFirst = time.Minute
+	retryMax   = time.Hour
+	// giveUpAfter is how long after its creation a row may be delivered.
+	// The last retry is due at that moment; a row claimed then or later is
+	// marked failed without being sent, and a delivery failing at or
+	// after it marks the row failed.
+	giveUpAfter = 24 * time.Hour
+	// sendTimeout bounds one Send.
+	sendTimeout = 30 * time.Second
+	// leaseFor is how long a claimed row is not due again. It outlasts
+	// sendTimeout and the final write, so a row is only claimed again when
+	// the process that claimed it stopped before recording the delivery.
+	leaseFor = 2 * time.Minute
+	// pollRetryMin and pollRetryMax bound the backoff after a database
+	// error while claiming rows.
+	pollRetryMin = time.Second
+	pollRetryMax = time.Minute
+)
+
+// Message is one notification for a Sender to deliver.
+type Message struct {
+	// ID is the notification_outbox row id.
+	ID string
+	// EventKey is the event's idempotency key.
+	EventKey string
+	Channel  Channel
+	Payload  Payload
+	// Attempt is this delivery's number, from 1.
+	Attempt int64
+}
+
+// Sender delivers notifications on one channel. Send returns nil once the
+// channel has accepted m, and an error otherwise; the worker retries it.
+// 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).
+type Sender interface {
+	Send(ctx context.Context, m Message) error
+}
+
+// Register makes sender the Sender of ch. It must be called before Start,
+// once per channel.
+func (s *Service) Register(ch Channel, sender Sender) error {
+	if ch != ChannelPush && ch != ChannelChat {
+		return fmt.Errorf("notify: register: unknown channel %q", ch)
+	}
+	if sender == nil {
+		return fmt.Errorf("notify: register %s: nil sender", ch)
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.started {
+		return fmt.Errorf("notify: register %s: worker already started", ch)
+	}
+	if _, ok := s.senders[ch]; ok {
+		return fmt.Errorf("notify: register %s: channel already has a sender", ch)
+	}
+	s.senders[ch] = sender
+	return nil
+}
+
+// Start starts the worker. It stops when ctx is cancelled; Wait waits for
+// it. A row whose delivery is cut short by ctx keeps its lease and is
+// delivered again once the lease ends.
+func (s *Service) Start(ctx context.Context) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.started {
+		return errors.New("notify: worker already started")
+	}
+	s.started = true
+	s.wg.Add(1)
+	go s.work(ctx)
+	return nil
+}
+
+// Wait blocks until the worker has stopped.
+func (s *Service) Wait() {
+	s.wg.Wait()
+}
+
+// wakeWorker gives the worker a token to look for due rows.
+func (s *Service) wakeWorker() {
+	select {
+	case s.wake <- struct{}{}:
+	default: // the worker already has a token and will look again
+	}
+}
+
+// work delivers due rows until ctx is cancelled, then sleeps until the next
+// pending row is due or Emit stores one. A database error is retried with
+// backoff.
+func (s *Service) work(ctx context.Context) {
+	defer s.wg.Done()
+	backoff := pollRetryMin
+	for ctx.Err() == nil {
+		wait, err := s.deliverDue(ctx)
+		if err != nil {
+			if ctx.Err() != nil {
+				return
+			}
+			s.logger.ErrorContext(ctx, "deliver notifications failed; retrying", "error", err, "retry_in", backoff)
+			wait, backoff = backoff, min(2*backoff, pollRetryMax)
+		} else {
+			backoff = pollRetryMin
+		}
+		var timeout <-chan time.Time
+		var timer *time.Timer
+		if wait >= 0 {
+			timer = time.NewTimer(wait)
+			timeout = timer.C
+		}
+		select {
+		case <-s.wake:
+		case <-timeout:
+		case <-ctx.Done():
+		}
+		if timer != nil {
+			timer.Stop()
+		}
+	}
+}
+
+// deliverDue delivers every row due now and returns how long until the next
+// pending row is due, or -1 when none is pending.
+func (s *Service) deliverDue(ctx context.Context) (time.Duration, error) {
+	q := db.New(s.st.Writer)
+	for ctx.Err() == nil {
+		now := s.now()
+		lease := sql.NullString{String: timestamp(now.Add(leaseFor)), Valid: true}
+		row, err := q.ClaimDueNotification(ctx, db.ClaimDueNotificationParams{LeaseUntil: lease, Now: timestamp(now)})
+		if errors.Is(err, sql.ErrNoRows) {
+			break
+		}
+		if err != nil {
+			return 0, fmt.Errorf("notify: claim notification: %w", err)
+		}
+		s.deliver(ctx, row)
+	}
+	if err := ctx.Err(); err != nil {
+		return 0, err
+	}
+	next, err := db.New(s.st.Reader).NextNotificationDue(ctx)
+	if errors.Is(err, sql.ErrNoRows) {
+		return -1, nil
+	}
+	if err != nil {
+		return 0, fmt.Errorf("notify: read next due notification: %w", err)
+	}
+	due, err := parseTimestamp(next.String)
+	if err != nil {
+		return 0, fmt.Errorf("notify: next due notification: %w", err)
+	}
+	return max(due.Sub(s.now()), 0), nil
+}
+
+// deliver sends a claimed row through its channel's sender and records the
+// outcome. A row that cannot be sent at all, because its payload does not
+// decode or its channel has no sender, is failed at once: retrying cannot
+// help. A row 24 hours or more past its creation is failed without being
+// sent: it is too stale to deliver.
+func (s *Service) deliver(ctx context.Context, row db.NotificationOutbox) {
+	logger := s.logger.With("notification_id", row.ID, "event_key", row.EventKey, "channel", row.Channel)
+	var payload Payload
+	if err := json.Unmarshal([]byte(row.Payload), &payload); err != nil {
+		logger.ErrorContext(ctx, "notification failed", "reason", "payload does not decode")
+		s.giveUp(ctx, logger, row, 0, "payload does not decode")
+		return
+	}
+	s.mu.Lock()
+	sender, ok := s.senders[Channel(row.Channel)]
+	s.mu.Unlock()
+	if !ok {
+		reason := fmt.Sprintf("no sender registered for channel %s", row.Channel)
+		logger.ErrorContext(ctx, "notification failed", "reason", reason)
+		s.giveUp(ctx, logger, row, 0, reason)
+		return
+	}
+
+	created, err := parseTimestamp(row.CreatedAt)
+	if err != nil {
+		reason := fmt.Sprintf("created_at does not parse: %v", err)
+		logger.ErrorContext(ctx, "notification failed", "reason", reason)
+		s.giveUp(ctx, logger, row, 0, reason)
+		return
+	}
+	deadline := created.Add(giveUpAfter)
+	if !s.now().Before(deadline) {
+		reason := "not delivered within 24 hours of creation"
+		if row.LastError.Valid {
+			reason += "; last error: " + row.LastError.String
+		}
+		logger.ErrorContext(ctx, "notification failed; giving up", "reason", reason)
+		s.giveUp(ctx, logger, row, 0, reason)
+		return
+	}
+
+	attempt := row.Attempts + 1
+	sendCtx, cancel := context.WithTimeout(ctx, sendTimeout)
+	err = sender.Send(sendCtx, Message{
+		ID: row.ID, EventKey: row.EventKey, Channel: Channel(row.Channel), Payload: payload, Attempt: attempt,
+	})
+	cancel()
+	now := s.now()
+	if err == nil {
+		s.record(ctx, logger, "record notification sent", func(write context.Context) (int64, error) {
+			return db.New(s.st.Writer).MarkNotificationSent(write, db.MarkNotificationSentParams{
+				Now: timestamp(now), ID: row.ID, LeaseUntil: row.NextAttemptAt,
+			})
+		})
+		logger.InfoContext(ctx, "notification sent", "attempt", attempt)
+		return
+	}
+	if ctx.Err() != nil {
+		logger.WarnContext(context.WithoutCancel(ctx), "notification delivery interrupted by shutdown; it is retried when its lease ends")
+		return
+	}
+
+	if !now.Before(deadline) {
+		logger.ErrorContext(ctx, "notification failed; giving up", "attempt", attempt, "error", err)
+		s.giveUp(ctx, logger, row, 1, err.Error())
+		return
+	}
+	next := now.Add(retryDelay(attempt))
+	if next.After(deadline) {
+		next = deadline
+	}
+	logger.WarnContext(ctx, "notification delivery failed; retrying", "attempt", attempt, "error", err, "retry_at", timestamp(next))
+	s.record(ctx, logger, "record notification retry", func(write context.Context) (int64, error) {
+		return db.New(s.st.Writer).RetryNotification(write, db.RetryNotificationParams{
+			NextAttemptAt: sql.NullString{String: timestamp(next), Valid: true},
+			LastError:     sql.NullString{String: err.Error(), Valid: true},
+			Now:           timestamp(now),
+			ID:            row.ID,
+			LeaseUntil:    row.NextAttemptAt,
+		})
+	})
+}
+
+// giveUp marks a claimed row failed with reason. attempted is 1 when a
+// delivery was attempted, else 0.
+func (s *Service) giveUp(ctx context.Context, logger *slog.Logger, row db.NotificationOutbox, attempted int64, reason string) {
+	now := s.now()
+	s.record(ctx, logger, "record notification failed", func(write context.Context) (int64, error) {
+		return db.New(s.st.Writer).FailNotification(write, db.FailNotificationParams{
+			Attempted:  attempted,
+			LastError:  sql.NullString{String: reason, Valid: true},
+			Now:        timestamp(now),
+			ID:         row.ID,
+			LeaseUntil: row.NextAttemptAt,
+		})
+	})
+}
+
+// record makes a row's final write for one delivery, even when ctx has been
+// cancelled, bounded by jobs.FinalWriteTimeout. A write that fails, or that
+// finds the row no longer leased to this claim, is logged; the row keeps
+// its lease and is delivered again once the lease ends.
+func (s *Service) record(ctx context.Context, logger *slog.Logger, what string, write func(context.Context) (int64, error)) {
+	attempt, cancel := jobs.FinalWriteContext(ctx)
+	defer cancel()
+	n, err := write(attempt)
+	if err != nil {
+		logger.ErrorContext(context.WithoutCancel(ctx), what+" failed; it is delivered again when its lease ends", "error", err)
+		return
+	}
+	if n != 1 {
+		logger.ErrorContext(context.WithoutCancel(ctx), what, "error", "notification is no longer leased to this delivery")
+	}
+}
+
+// retryDelay is the wait after the attempt-th failed delivery: retryFirst,
+// doubling with each failure, at most retryMax.
+func retryDelay(attempt int64) time.Duration {
+	d := retryFirst
+	for i := int64(1); i < attempt && d < retryMax; i++ {
+		d *= 2
+	}
+	return min(d, retryMax)
+}

internal/push/push.go

@@ -0,0 +1,203 @@
+// Package push keeps the household's Web Push subscriptions, one per
+// browser, keyed by the push service endpoint the browser was given, and
+// the VAPID public key browsers subscribe with.
+package push
+
+import (
+	"context"
+	"crypto/ecdh"
+	"database/sql"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"net/url"
+	"strings"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/db"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/vapid"
+)
+
+// Limits on a subscription's fields.
+const (
+	MaxEndpointBytes  = 2048
+	MaxUserAgentBytes = 512
+	p256dhSize        = 65 // uncompressed P-256 point
+	authSize          = 16
+)
+
+// keyEncoding is the unpadded base64url PushSubscription.toJSON() gives
+// the keys in.
+var keyEncoding = base64.RawURLEncoding
+
+// Subscription is a stored push subscription. Its keys are never returned:
+// only the sender needs them.
+type Subscription struct {
+	ID        string  `json:"id"`
+	Endpoint  string  `json:"endpoint"`
+	UserAgent *string `json:"user_agent"`
+	CreatedAt string  `json:"created_at"`
+	UpdatedAt string  `json:"updated_at"`
+}
+
+// SubscribeRequest is a browser's push subscription: the endpoint and keys
+// of its PushSubscription, and optionally a user agent to tell the
+// household's devices apart.
+type SubscribeRequest struct {
+	Endpoint  string
+	P256dh    string
+	Auth      string
+	UserAgent *string
+}
+
+// Problem is one invalid field of a request, named by its JSON key.
+type Problem struct {
+	Field  string
+	Reason string
+}
+
+// ValidationError lists every invalid field of a request.
+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 push subscription: " + strings.Join(parts, "; ")
+}
+
+// Service stores push subscriptions.
+type Service struct {
+	st        *store.Store
+	publicKey string
+}
+
+// NewService returns a Service over st handing out publicKey, the VAPID
+// public key in vapid's encoding.
+func NewService(st *store.Store, publicKey string) (*Service, error) {
+	if st == nil {
+		return nil, errors.New("push: nil store")
+	}
+	if _, err := vapid.ParsePublicKey(publicKey); err != nil {
+		return nil, fmt.Errorf("push: VAPID public key: %w", err)
+	}
+	return &Service{st: st, publicKey: publicKey}, nil
+}
+
+// PublicKey returns the VAPID public key, for applicationServerKey.
+func (s *Service) PublicKey() string { return s.publicKey }
+
+// Subscribe stores req by its endpoint. An endpoint already stored keeps
+// its id and created_at and has its keys and user agent replaced, so
+// subscribing twice leaves one subscription. An invalid request is a
+// *ValidationError.
+func (s *Service) Subscribe(ctx context.Context, req SubscribeRequest) (Subscription, error) {
+	var problems []Problem
+	if reason := checkEndpoint(req.Endpoint); reason != "" {
+		problems = append(problems, Problem{"endpoint", reason})
+	}
+	if reason := checkP256dh(req.P256dh); reason != "" {
+		problems = append(problems, Problem{"keys.p256dh", reason})
+	}
+	if reason := checkAuth(req.Auth); reason != "" {
+		problems = append(problems, Problem{"keys.auth", reason})
+	}
+	var ua sql.NullString
+	if req.UserAgent != nil {
+		if reason := checkUserAgent(*req.UserAgent); reason != "" {
+			problems = append(problems, Problem{"user_agent", reason})
+		}
+		ua = sql.NullString{String: *req.UserAgent, Valid: true}
+	}
+	if len(problems) > 0 {
+		return Subscription{}, &ValidationError{Problems: problems}
+	}
+
+	now := store.Now().String()
+	row, err := db.New(s.st.Writer).UpsertPushSubscription(ctx, db.UpsertPushSubscriptionParams{
+		ID:        store.NewID(),
+		Endpoint:  req.Endpoint,
+		P256dh:    req.P256dh,
+		Auth:      req.Auth,
+		UserAgent: ua,
+		CreatedAt: now,
+		UpdatedAt: now,
+	})
+	if err != nil {
+		return Subscription{}, fmt.Errorf("push: store subscription: %w", err)
+	}
+	sub := Subscription{ID: row.ID, Endpoint: row.Endpoint, CreatedAt: row.CreatedAt, UpdatedAt: row.UpdatedAt}
+	if row.UserAgent.Valid {
+		sub.UserAgent = &row.UserAgent.String
+	}
+	return sub, nil
+}
+
+// Unsubscribe removes the subscription for endpoint and reports whether
+// one was stored. An endpoint that is not stored is not an error: the
+// browser may unsubscribe after a failed delivery already removed it. An
+// invalid endpoint is a *ValidationError.
+func (s *Service) Unsubscribe(ctx context.Context, endpoint string) (bool, error) {
+	if reason := checkEndpoint(endpoint); reason != "" {
+		return false, &ValidationError{Problems: []Problem{{"endpoint", reason}}}
+	}
+	n, err := db.New(s.st.Writer).DeletePushSubscription(ctx, endpoint)
+	if err != nil {
+		return false, fmt.Errorf("push: delete subscription: %w", err)
+	}
+	return n > 0, nil
+}
+
+// checkEndpoint returns why endpoint is not a push service URL, or "".
+// Push services are always reached over https.
+func checkEndpoint(endpoint string) string {
+	if endpoint == "" {
+		return "required"
+	}
+	if len(endpoint) > MaxEndpointBytes {
+		return fmt.Sprintf("longer than %d bytes", MaxEndpointBytes)
+	}
+	u, err := url.Parse(endpoint)
+	if err != nil || u.Scheme != "https" || u.Host == "" || u.User != nil || u.Fragment != "" {
+		return "want an absolute https:// URL without credentials or fragment"
+	}
+	return ""
+}
+
+func checkP256dh(s string) string {
+	if s == "" {
+		return "required"
+	}
+	b, err := keyEncoding.DecodeString(s)
+	if err != nil || len(b) != p256dhSize {
+		return fmt.Sprintf("want the %d-byte uncompressed P-256 point in unpadded base64url", p256dhSize)
+	}
+	if _, err := ecdh.P256().NewPublicKey(b); err != nil {
+		return "not a point on P-256"
+	}
+	return ""
+}
+
+func checkAuth(s string) string {
+	if s == "" {
+		return "required"
+	}
+	b, err := keyEncoding.DecodeString(s)
+	if err != nil || len(b) != authSize {
+		return fmt.Sprintf("want %d bytes in unpadded base64url", authSize)
+	}
+	return ""
+}
+
+func checkUserAgent(s string) string {
+	switch {
+	case strings.TrimSpace(s) == "":
+		return "must not be blank; omit it instead"
+	case len(s) > MaxUserAgentBytes:
+		return fmt.Sprintf("longer than %d bytes", MaxUserAgentBytes)
+	}
+	return ""
+}

internal/push/push_test.go

@@ -0,0 +1,224 @@
+package push
+
+import (
+	"context"
+	"crypto/ecdh"
+	"crypto/rand"
+	"encoding/base64"
+	"errors"
+	"strings"
+	"testing"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/vapid"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/migrations"
+)
+
+const endpoint = "https://fcm.googleapis.com/fcm/send/abc123"
+
+func newTestService(t *testing.T) (*Service, *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)
+	}
+	pair, err := vapid.Generate()
+	if err != nil {
+		t.Fatal(err)
+	}
+	svc, err := NewService(st, pair.PublicKey)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return svc, st
+}
+
+// browserKeys returns a p256dh and auth as a browser's
+// PushSubscription.toJSON() gives them.
+func browserKeys(t *testing.T) (string, string) {
+	t.Helper()
+	k, err := ecdh.P256().GenerateKey(rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	auth := make([]byte, 16)
+	rand.Read(auth)
+	return base64.RawURLEncoding.EncodeToString(k.PublicKey().Bytes()), base64.RawURLEncoding.EncodeToString(auth)
+}
+
+type storedRow struct {
+	id, p256dh, auth, createdAt, updatedAt string
+	ua                                     *string
+	failures                               int
+}
+
+func rows(t *testing.T, st *store.Store) map[string]storedRow {
+	t.Helper()
+	rs, err := st.Reader.Query(`SELECT endpoint, id, p256dh, auth, user_agent, failure_count, created_at, updated_at FROM push_subscriptions`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer rs.Close()
+	got := map[string]storedRow{}
+	for rs.Next() {
+		var ep string
+		var r storedRow
+		if err := rs.Scan(&ep, &r.id, &r.p256dh, &r.auth, &r.ua, &r.failures, &r.createdAt, &r.updatedAt); err != nil {
+			t.Fatal(err)
+		}
+		got[ep] = r
+	}
+	if err := rs.Err(); err != nil {
+		t.Fatal(err)
+	}
+	return got
+}
+
+func TestNewServiceRefusesBadPublicKey(t *testing.T) {
+	t.Parallel()
+	_, st := newTestService(t)
+	if _, err := NewService(st, "not-a-key"); err == nil {
+		t.Error("NewService accepted a malformed public key")
+	}
+	if _, err := NewService(nil, ""); err == nil {
+		t.Error("NewService accepted a nil store")
+	}
+}
+
+func TestSubscribeUpsertsByEndpoint(t *testing.T) {
+	t.Parallel()
+	svc, st := newTestService(t)
+	ctx := context.Background()
+	p1, a1 := browserKeys(t)
+	ua := "Mozilla/5.0 (iPad)"
+
+	first, err := svc.Subscribe(ctx, SubscribeRequest{Endpoint: endpoint, P256dh: p1, Auth: a1, UserAgent: &ua})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if first.ID == "" || first.Endpoint != endpoint || first.UserAgent == nil || *first.UserAgent != ua || first.CreatedAt != first.UpdatedAt {
+		t.Errorf("first Subscribe = %+v", first)
+	}
+	if _, err := st.Writer.Exec(`UPDATE push_subscriptions SET failure_count = 3`); err != nil {
+		t.Fatal(err)
+	}
+
+	// The same endpoint again, with the same keys and then rotated ones,
+	// updates the one row.
+	again, err := svc.Subscribe(ctx, SubscribeRequest{Endpoint: endpoint, P256dh: p1, Auth: a1, UserAgent: &ua})
+	if err != nil {
+		t.Fatal(err)
+	}
+	p2, a2 := browserKeys(t)
+	rotated, err := svc.Subscribe(ctx, SubscribeRequest{Endpoint: endpoint, P256dh: p2, Auth: a2})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, s := range []Subscription{again, rotated} {
+		if s.ID != first.ID || s.CreatedAt != first.CreatedAt {
+			t.Errorf("resubscribe = %+v, want id %s and created_at %s kept", s, first.ID, first.CreatedAt)
+		}
+	}
+	if rotated.UserAgent != nil {
+		t.Errorf("resubscribe without user_agent kept %q", *rotated.UserAgent)
+	}
+	got := rows(t, st)
+	if len(got) != 1 {
+		t.Fatalf("rows = %d, want 1: %+v", len(got), got)
+	}
+	r := got[endpoint]
+	if r.p256dh != p2 || r.auth != a2 || r.ua != nil || r.failures != 0 || r.updatedAt < r.createdAt {
+		t.Errorf("stored row = %+v, want rotated keys, no user agent, failures cleared", r)
+	}
+
+	// A second browser is a second row.
+	other := endpoint + "-other"
+	if _, err := svc.Subscribe(ctx, SubscribeRequest{Endpoint: other, P256dh: p1, Auth: a1}); err != nil {
+		t.Fatal(err)
+	}
+	if got := rows(t, st); len(got) != 2 {
+		t.Errorf("rows after a second endpoint = %d, want 2", len(got))
+	}
+}
+
+func TestUnsubscribe(t *testing.T) {
+	t.Parallel()
+	svc, st := newTestService(t)
+	ctx := context.Background()
+	p, a := browserKeys(t)
+	for _, ep := range []string{endpoint, endpoint + "-keep"} {
+		if _, err := svc.Subscribe(ctx, SubscribeRequest{Endpoint: ep, P256dh: p, Auth: a}); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	removed, err := svc.Unsubscribe(ctx, endpoint)
+	if err != nil || !removed {
+		t.Errorf("Unsubscribe = %v, %v; want true, nil", removed, err)
+	}
+	got := rows(t, st)
+	if _, ok := got[endpoint]; ok || len(got) != 1 {
+		t.Errorf("rows after Unsubscribe = %+v, want only the other endpoint", got)
+	}
+	removed, err = svc.Unsubscribe(ctx, endpoint)
+	if err != nil || removed {
+		t.Errorf("Unsubscribe of an endpoint not stored = %v, %v; want false, nil", removed, err)
+	}
+	var invalid *ValidationError
+	if _, err := svc.Unsubscribe(ctx, "http://push.example.com/x"); !errors.As(err, &invalid) {
+		t.Errorf("Unsubscribe of an http endpoint = %v, want *ValidationError", err)
+	}
+}
+
+func TestSubscribeValidates(t *testing.T) {
+	t.Parallel()
+	svc, st := newTestService(t)
+	p, a := browserKeys(t)
+	pair, err := vapid.Generate()
+	if err != nil {
+		t.Fatal(err)
+	}
+	blank, long := "  ", strings.Repeat("x", MaxUserAgentBytes+1)
+	offCurve := make([]byte, 65)
+	offCurve[0] = 0x04
+	raw := base64.RawURLEncoding.EncodeToString
+
+	for _, tc := range []struct {
+		name  string
+		req   SubscribeRequest
+		field string
+	}{
+		{"missing endpoint", SubscribeRequest{P256dh: p, Auth: a}, "endpoint"},
+		{"http endpoint", SubscribeRequest{Endpoint: "http://push.example.com/x", P256dh: p, Auth: a}, "endpoint"},
+		{"relative endpoint", SubscribeRequest{Endpoint: "/fcm/send/x", P256dh: p, Auth: a}, "endpoint"},
+		{"endpoint with credentials", SubscribeRequest{Endpoint: "https://u:p@push.example.com/x", P256dh: p, Auth: a}, "endpoint"},
+		{"endpoint too long", SubscribeRequest{Endpoint: "https://push.example.com/" + strings.Repeat("x", MaxEndpointBytes), P256dh: p, Auth: a}, "endpoint"},
+		{"missing p256dh", SubscribeRequest{Endpoint: endpoint, Auth: a}, "keys.p256dh"},
+		{"padded p256dh", SubscribeRequest{Endpoint: endpoint, P256dh: p + "=", Auth: a}, "keys.p256dh"},
+		{"short p256dh", SubscribeRequest{Endpoint: endpoint, P256dh: a, Auth: a}, "keys.p256dh"},
+		{"p256dh off the curve", SubscribeRequest{Endpoint: endpoint, P256dh: raw(offCurve), Auth: a}, "keys.p256dh"},
+		{"private key as p256dh", SubscribeRequest{Endpoint: endpoint, P256dh: pair.PrivateKey, Auth: a}, "keys.p256dh"},
+		{"missing auth", SubscribeRequest{Endpoint: endpoint, P256dh: p}, "keys.auth"},
+		{"long auth", SubscribeRequest{Endpoint: endpoint, P256dh: p, Auth: raw(make([]byte, 32))}, "keys.auth"},
+		{"blank user agent", SubscribeRequest{Endpoint: endpoint, P256dh: p, Auth: a, UserAgent: &blank}, "user_agent"},
+		{"long user agent", SubscribeRequest{Endpoint: endpoint, P256dh: p, Auth: a, UserAgent: &long}, "user_agent"},
+	} {
+		_, err := svc.Subscribe(context.Background(), tc.req)
+		var invalid *ValidationError
+		if !errors.As(err, &invalid) || len(invalid.Problems) != 1 || invalid.Problems[0].Field != tc.field {
+			t.Errorf("%s: Subscribe error = %v, want one problem for %s", tc.name, err, tc.field)
+		}
+	}
+	if got := rows(t, st); len(got) != 0 {
+		t.Errorf("invalid requests stored %d rows", len(got))
+	}
+}

internal/server/aisettings_test.go

@@ -29,7 +29,7 @@ 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),
-		newTestPlan(t), newTestShopping(t), newTestGoogle(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		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)
 	}

internal/server/dinners_test.go

@@ -92,7 +92,7 @@ func newDinnersEnv(t *testing.T) *dinnersEnv {
 		t.Fatal(err)
 	}
 	e.h, err = NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t),
-		svc, newTestSuggest(t), newTestPlan(t), newTestShopping(t), newTestGoogle(t), runner, newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		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)
 	}

internal/server/google_test.go

@@ -69,7 +69,7 @@ func newGoogleEnv(t *testing.T) *googleEnv {
 	}
 	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),
-		newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestShopping(t), svc, newTestRunner(t), newTestPhotos(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 {
 		t.Fatal(err)

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), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		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)}})
 	if err != nil {
 		t.Fatal(err)
 	}

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), newTestRunner(t),
+	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),
 		photos, fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)

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), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		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)}})
 	if err != nil {
 		t.Fatal(err)
 	}

internal/server/plans_test.go

@@ -94,7 +94,7 @@ func newPlansRouterTitled(t *testing.T, title shopping.Titler) plansEnv {
 		t.Fatal(err)
 	}
 	h, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t),
-		newTestDinners(t), newTestSuggest(t), svc, shop, googleSvc, runner, newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		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)
 	}

internal/server/push.go

@@ -0,0 +1,98 @@
+package server
+
+import (
+	"errors"
+	"log/slog"
+	"net/http"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/push"
+)
+
+// maxPushBody bounds a POST or DELETE /push/subscriptions body: an endpoint
+// of push.MaxEndpointBytes, the keys and a user agent of
+// push.MaxUserAgentBytes, with room for JSON escaping.
+const maxPushBody = 8 << 10
+
+type vapidPublicKeyResponse struct {
+	PublicKey string `json:"public_key"`
+}
+
+// pushSubscriptionBody is the POST /push/subscriptions body: the
+// endpoint and keys of PushSubscription.toJSON(), without its
+// expirationTime, and an optional user_agent.
+type pushSubscriptionBody struct {
+	Endpoint  string               `json:"endpoint"`
+	Keys      pushSubscriptionKeys `json:"keys"`
+	UserAgent *string              `json:"user_agent"`
+}
+
+type pushSubscriptionKeys struct {
+	P256dh string `json:"p256dh"`
+	Auth   string `json:"auth"`
+}
+
+// pushUnsubscribeBody is the DELETE /push/subscriptions body.
+type pushUnsubscribeBody struct {
+	Endpoint string `json:"endpoint"`
+}
+
+// getVAPIDPublicKey answers GET /push/vapid-public-key with the key
+// browsers pass as applicationServerKey. The private key is never served.
+func getVAPIDPublicKey(logger *slog.Logger, svc *push.Service) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		writeJSON(w, r, logger, http.StatusOK, vapidPublicKeyResponse{PublicKey: svc.PublicKey()})
+	}
+}
+
+// postPushSubscription stores the browser's subscription by its endpoint
+// and answers 200 with it, without its keys. Posting an endpoint already
+// stored updates it.
+func postPushSubscription(logger *slog.Logger, svc *push.Service) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		body, err := decodePatch[pushSubscriptionBody](http.MaxBytesReader(w, r.Body, maxPushBody))
+		if err != nil {
+			writeError(w, r, logger, http.StatusBadRequest, "invalid_request", err.Error())
+			return
+		}
+		sub, err := svc.Subscribe(r.Context(), push.SubscribeRequest{
+			Endpoint:  body.Endpoint,
+			P256dh:    body.Keys.P256dh,
+			Auth:      body.Keys.Auth,
+			UserAgent: body.UserAgent,
+		})
+		if err != nil {
+			writePushError(w, r, logger, "store push subscription", err)
+			return
+		}
+		writeJSON(w, r, logger, http.StatusOK, sub)
+	}
+}
+
+// deletePushSubscription removes the subscription for the body's endpoint
+// and answers 204, whether or not it was stored.
+func deletePushSubscription(logger *slog.Logger, svc *push.Service) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		body, err := decodePatch[pushUnsubscribeBody](http.MaxBytesReader(w, r.Body, maxPushBody))
+		if err != nil {
+			writeError(w, r, logger, http.StatusBadRequest, "invalid_request", err.Error())
+			return
+		}
+		if _, err := svc.Unsubscribe(r.Context(), body.Endpoint); err != nil {
+			writePushError(w, r, logger, "delete push subscription", err)
+			return
+		}
+		w.WriteHeader(http.StatusNoContent)
+	}
+}
+
+// writePushError maps a push.Service error to its API error: an invalid
+// subscription is 400 invalid_subscription, anything else 500.
+func writePushError(w http.ResponseWriter, r *http.Request, logger *slog.Logger, action string, err error) {
+	var invalid *push.ValidationError
+	if errors.As(err, &invalid) {
+		writeError(w, r, logger, http.StatusBadRequest, "invalid_subscription", invalid.Error())
+		return
+	}
+	logger.ErrorContext(r.Context(), action, "error", err)
+	writeError(w, r, logger, http.StatusInternalServerError, "internal", "internal error")
+}

internal/server/push_test.go

@@ -0,0 +1,284 @@
+package server
+
+import (
+	"crypto/ecdh"
+	"crypto/rand"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"testing/fstest"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/push"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/vapid"
+)
+
+const (
+	vapidPublicKeyPath    = "/api/v1/push/vapid-public-key"
+	pushSubscriptionsPath = "/api/v1/push/subscriptions"
+	testPushEndpoint      = "https://updates.push.services.mozilla.com/wpush/v2/gAAAAABk"
+)
+
+// newTestPush returns a push service over a migrated temp database with a
+// new VAPID key pair.
+func newTestPush(t *testing.T) *push.Service {
+	t.Helper()
+	svc, _, _ := newTestPushWith(t)
+	return svc
+}
+
+// newTestPushWith is newTestPush also returning its store and key pair.
+func newTestPushWith(t *testing.T) (*push.Service, *store.Store, vapid.KeyPair) {
+	t.Helper()
+	pair, err := vapid.Generate()
+	if err != nil {
+		t.Fatal(err)
+	}
+	st := newTestStore(t)
+	svc, err := push.NewService(st, pair.PublicKey)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return svc, st, pair
+}
+
+// newPushRouter returns a router serving svc.
+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),
+		newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	return r
+}
+
+// subscriptionJSON returns a POST /push/subscriptions body for endpoint
+// with new browser keys.
+func subscriptionJSON(t *testing.T, endpoint, userAgent string) string {
+	t.Helper()
+	k, err := ecdh.P256().GenerateKey(rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	auth := make([]byte, 16)
+	rand.Read(auth)
+	body := map[string]any{
+		"endpoint": endpoint,
+		"keys": map[string]string{
+			"p256dh": base64.RawURLEncoding.EncodeToString(k.PublicKey().Bytes()),
+			"auth":   base64.RawURLEncoding.EncodeToString(auth),
+		},
+	}
+	if userAgent != "" {
+		body["user_agent"] = userAgent
+	}
+	b, err := json.Marshal(body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return string(b)
+}
+
+func countPushSubscriptions(t *testing.T, st *store.Store) int {
+	t.Helper()
+	var n int
+	if err := st.Reader.QueryRow(`SELECT count(*) FROM push_subscriptions`).Scan(&n); err != nil {
+		t.Fatal(err)
+	}
+	return n
+}
+
+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 {
+		t.Fatal("NewRouter accepted a nil push service")
+	}
+}
+
+func TestPushAPI(t *testing.T) {
+	t.Parallel()
+	svc, st, pair := newTestPushWith(t)
+	router := newPushRouter(t, svc)
+	var bodies []string
+	call := func(method, target, body string) *httptest.ResponseRecorder {
+		t.Helper()
+		var r io.Reader
+		if body != "" {
+			r = strings.NewReader(body)
+		}
+		rec := httptest.NewRecorder()
+		router.ServeHTTP(rec, signedIn(method, target, r))
+		bodies = append(bodies, rec.Body.String())
+		return rec
+	}
+	decode := func(rec *httptest.ResponseRecorder) map[string]any {
+		t.Helper()
+		var m map[string]any
+		if err := json.Unmarshal(rec.Body.Bytes(), &m); err != nil {
+			t.Fatalf("decode %q: %v", rec.Body.String(), err)
+		}
+		return m
+	}
+
+	rec := call(http.MethodGet, vapidPublicKeyPath, "")
+	if body := decode(rec); rec.Code != http.StatusOK || len(body) != 1 || body["public_key"] != pair.PublicKey {
+		t.Errorf("GET public key = %d %s, want only the public key", rec.Code, rec.Body.String())
+	}
+
+	// Posting the same endpoint twice keeps one subscription, updated.
+	rec = call(http.MethodPost, pushSubscriptionsPath, subscriptionJSON(t, testPushEndpoint, "Firefox on the kitchen tablet"))
+	first := decode(rec)
+	if rec.Code != http.StatusOK || first["endpoint"] != testPushEndpoint || first["user_agent"] != "Firefox on the kitchen tablet" || first["id"] == "" {
+		t.Errorf("POST subscription = %d %s", rec.Code, rec.Body.String())
+	}
+	if _, ok := first["keys"]; ok {
+		t.Errorf("POST response holds the keys: %s", rec.Body.String())
+	}
+	rec = call(http.MethodPost, pushSubscriptionsPath, subscriptionJSON(t, testPushEndpoint, "Firefox 140"))
+	again := decode(rec)
+	if rec.Code != http.StatusOK || again["id"] != first["id"] || again["created_at"] != first["created_at"] || again["user_agent"] != "Firefox 140" {
+		t.Errorf("POST same endpoint = %d %s, want the first subscription updated", rec.Code, rec.Body.String())
+	}
+	if n := countPushSubscriptions(t, st); n != 1 {
+		t.Errorf("subscriptions after posting one endpoint twice = %d, want 1", n)
+	}
+	rec = call(http.MethodPost, pushSubscriptionsPath, subscriptionJSON(t, testPushEndpoint+"-phone", ""))
+	if body := decode(rec); rec.Code != http.StatusOK || body["user_agent"] != nil {
+		t.Errorf("POST second endpoint = %d %s", rec.Code, rec.Body.String())
+	}
+	if n := countPushSubscriptions(t, st); n != 2 {
+		t.Errorf("subscriptions after a second endpoint = %d, want 2", n)
+	}
+
+	for _, bad := range []struct{ body, code string }{
+		{"", "invalid_request"},
+		{`{"endpoint":"` + testPushEndpoint + `","keys":{"p256dh":"x","auth":"y"},"expirationTime":null}`, "invalid_request"},
+		{`{"endpoint":"` + testPushEndpoint + `","keys":{"p256dh":"x","auth":"y"},"extra":1}`, "invalid_request"},
+		{`{"endpoint":"` + testPushEndpoint + `"}`, "invalid_subscription"},
+		{`{"endpoint":"` + testPushEndpoint + `","keys":{"p256dh":"x","auth":"y"}}`, "invalid_subscription"},
+		{subscriptionJSON(t, "http://push.example.com/x", ""), "invalid_subscription"},
+		{`{"endpoint":"https://push.example.com/` + strings.Repeat("x", maxPushBody) + `"}`, "invalid_request"},
+	} {
+		rec := call(http.MethodPost, pushSubscriptionsPath, bad.body)
+		if rec.Code != http.StatusBadRequest || !strings.Contains(rec.Body.String(), `"code":"`+bad.code+`"`) {
+			t.Errorf("POST %.80s = %d %s, want 400 %s", bad.body, rec.Code, rec.Body.String(), bad.code)
+		}
+	}
+	if n := countPushSubscriptions(t, st); n != 2 {
+		t.Errorf("subscriptions after invalid posts = %d, want 2", n)
+	}
+
+	// DELETE removes by endpoint and is 204 whether or not it was stored.
+	for i := range 2 {
+		rec = call(http.MethodDelete, pushSubscriptionsPath, `{"endpoint":"`+testPushEndpoint+`"}`)
+		if rec.Code != http.StatusNoContent || rec.Body.Len() != 0 {
+			t.Errorf("DELETE #%d = %d %s, want 204", i+1, rec.Code, rec.Body.String())
+		}
+	}
+	if n := countPushSubscriptions(t, st); n != 1 {
+		t.Errorf("subscriptions after DELETE = %d, want 1", n)
+	}
+	for _, bad := range []string{"", `{}`, `{"endpoint":"not a url"}`} {
+		rec := call(http.MethodDelete, pushSubscriptionsPath, bad)
+		if rec.Code != http.StatusBadRequest {
+			t.Errorf("DELETE %q = %d %s, want 400", bad, rec.Code, rec.Body.String())
+		}
+	}
+	if n := countPushSubscriptions(t, st); n != 1 {
+		t.Errorf("subscriptions after invalid deletes = %d, want 1", n)
+	}
+
+	// The private key never leaves the process, in any encoding.
+	priv, err := base64.RawURLEncoding.DecodeString(pair.PrivateKey)
+	if err != nil {
+		t.Fatal(err)
+	}
+	leaks := []string{
+		pair.PrivateKey,
+		pair.PrivateKey[:16],
+		base64.StdEncoding.EncodeToString(priv),
+		base64.RawStdEncoding.EncodeToString(priv)[:16],
+		hex.EncodeToString(priv),
+	}
+	for _, b := range bodies {
+		for _, leak := range leaks {
+			if strings.Contains(b, leak) {
+				t.Errorf("response holds the VAPID private key: %s", b)
+			}
+		}
+	}
+}
+
+func TestPushSubscriptionsNeedCSRF(t *testing.T) {
+	t.Parallel()
+	svc, st, _ := newTestPushWith(t)
+	router := newPushRouter(t, svc)
+	if _, err := svc.Subscribe(t.Context(), push.SubscribeRequest{Endpoint: testPushEndpoint + "-stored", P256dh: mustP256dh(t), Auth: "AAAAAAAAAAAAAAAAAAAAAA"}); err != nil {
+		t.Fatal(err)
+	}
+	for _, tc := range []struct {
+		method, body string
+	}{
+		{http.MethodPost, subscriptionJSON(t, testPushEndpoint, "")},
+		{http.MethodDelete, `{"endpoint":"` + testPushEndpoint + `-stored"}`},
+	} {
+		for _, header := range []*string{nil, ptr(""), ptr("wrong-token")} {
+			req := httptest.NewRequest(tc.method, pushSubscriptionsPath, strings.NewReader(tc.body))
+			req.AddCookie(validSessionCookie)
+			if header != nil {
+				req.Header.Set(CSRFHeader, *header)
+			}
+			rec := httptest.NewRecorder()
+			router.ServeHTTP(rec, req)
+			if rec.Code != http.StatusForbidden || rec.Body.String() != csrfJSON {
+				t.Errorf("%s without a valid CSRF token (%v) = %d %s, want 403 csrf", tc.method, header, rec.Code, rec.Body.String())
+			}
+		}
+	}
+	if n := countPushSubscriptions(t, st); n != 1 {
+		t.Errorf("subscriptions after refused requests = %d, want the 1 stored before", n)
+	}
+	// GET needs no token.
+	req := httptest.NewRequest(http.MethodGet, vapidPublicKeyPath, nil)
+	req.AddCookie(validSessionCookie)
+	rec := httptest.NewRecorder()
+	router.ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Errorf("GET public key without CSRF token = %d, want 200", rec.Code)
+	}
+}
+
+func TestPushNeedsSession(t *testing.T) {
+	t.Parallel()
+	router := newPushRouter(t, newTestPush(t))
+	for _, method := range []string{http.MethodGet, http.MethodPost, http.MethodDelete} {
+		target := pushSubscriptionsPath
+		if method == http.MethodGet {
+			target = vapidPublicKeyPath
+		}
+		rec := httptest.NewRecorder()
+		router.ServeHTTP(rec, httptest.NewRequest(method, target, nil))
+		if rec.Code != http.StatusUnauthorized {
+			t.Errorf("%s %s without a session = %d, want 401", method, target, rec.Code)
+		}
+	}
+}
+
+func mustP256dh(t *testing.T) string {
+	t.Helper()
+	k, err := ecdh.P256().GenerateKey(rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return base64.RawURLEncoding.EncodeToString(k.PublicKey().Bytes())
+}

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), newTestRunner(t),
+	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),
 		newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)

internal/server/server.go

@@ -18,6 +18,7 @@ import (
 	"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/plan"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/push"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/recipes"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/shopping"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/suggest"
@@ -55,12 +56,14 @@ type RouteMounter interface {
 // /api/v1/shopping/items/{id}; googleSvc serves GET
 // /api/v1/integrations/google and its /connect, /callback and /calendars,
 // PUT /api/v1/integrations/google/calendar and DELETE
-// /api/v1/integrations/google; runner serves
+// /api/v1/integrations/google; pushSvc serves GET
+// /api/v1/push/vapid-public-key and POST and DELETE
+// /api/v1/push/subscriptions; runner serves
 // POST /api/v1/jobs and GET /api/v1/jobs/{id}; photos serves
 // 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, 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, 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")
 	}
@@ -85,6 +88,9 @@ func NewRouter(logger *slog.Logger, version string, trusted forwarded.Trusted, a
 	if googleSvc == nil {
 		return nil, errors.New("server: nil Google Calendar service")
 	}
+	if pushSvc == nil {
+		return nil, errors.New("server: nil push service")
+	}
 	if runner == nil {
 		return nil, errors.New("server: nil job runner")
 	}
@@ -158,6 +164,9 @@ func NewRouter(logger *slog.Logger, version string, trusted forwarded.Trusted, a
 	apiV1.Delete("/integrations/google", deleteGoogle(logger, googleSvc))
 	apiV1.Get("/integrations/google/calendars", getGoogleCalendars(logger, googleSvc))
 	apiV1.Put("/integrations/google/calendar", putGoogleCalendar(logger, googleSvc))
+	apiV1.Get("/push/vapid-public-key", getVAPIDPublicKey(logger, pushSvc))
+	apiV1.Post("/push/subscriptions", postPushSubscription(logger, pushSvc))
+	apiV1.Delete("/push/subscriptions", deletePushSubscription(logger, pushSvc))
 	apiV1.Post("/jobs", postJob(logger, runner))
 	apiV1.Get("/jobs/{id}", getJob(logger, runner))
 	media.Get("/photos/{name}", getPhoto(logger, photos))

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), runner, newTestPhotos(t), assets)
+	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)
 	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), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == 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 {
 		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), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == 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 {
 		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), newTestRunner(t), nil, fstest.MapFS{"index.html": {}}); err == 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 {
 		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), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == 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 {
 		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), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == 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 {
 		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), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == 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 {
 		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), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == 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 {
 		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), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == 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 {
 		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, newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == 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 {
 		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), nil, newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == 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 {
 		t.Fatal("NewRouter accepted a nil job runner")
 	}
 }

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), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		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)}})
 	if err != nil {
 		t.Fatal(err)
 	}

internal/server/suggestions_test.go

@@ -45,7 +45,7 @@ func newSuggestionsRouter(t *testing.T, names ...string) (http.Handler, *store.S
 		t.Fatal(err)
 	}
 	h, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t),
-		newTestDinners(t), svc, newTestPlan(t), newTestShopping(t), newTestGoogle(t), runner, newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		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)
 	}

internal/vapid/vapid.go

@@ -0,0 +1,87 @@
+// Package vapid generates and validates the VAPID key pair Web Push signs
+// with (RFC 8292): a P-256 (ES256) key pair in the encoding webpush-go
+// reads. Both keys are unpadded base64url: the public key is the 65-byte
+// uncompressed point and the private key the 32-byte scalar.
+package vapid
+
+import (
+	"crypto/ecdh"
+	"crypto/rand"
+	"encoding/base64"
+	"errors"
+	"fmt"
+)
+
+// encoding is unpadded base64url. Strict refuses non-zero trailing bits, so
+// every key has exactly one accepted spelling.
+var encoding = base64.RawURLEncoding.Strict()
+
+const (
+	publicKeySize  = 65 // 0x04 || X || Y
+	privateKeySize = 32
+)
+
+// KeyPair is a VAPID key pair in its stored encoding.
+type KeyPair struct {
+	PublicKey  string
+	PrivateKey string
+}
+
+// Generate returns a new random key pair.
+func Generate() (KeyPair, error) {
+	k, err := ecdh.P256().GenerateKey(rand.Reader)
+	if err != nil {
+		return KeyPair{}, fmt.Errorf("vapid: generate key: %w", err)
+	}
+	return KeyPair{
+		PublicKey:  encoding.EncodeToString(k.PublicKey().Bytes()),
+		PrivateKey: encoding.EncodeToString(k.Bytes()),
+	}, nil
+}
+
+// ParsePublicKey parses an encoded public key, which must be a point on
+// P-256.
+func ParsePublicKey(s string) (*ecdh.PublicKey, error) {
+	b, err := encoding.DecodeString(s)
+	if err != nil {
+		return nil, errors.New("not unpadded base64url")
+	}
+	if len(b) != publicKeySize || b[0] != 0x04 {
+		return nil, fmt.Errorf("want the %d-byte uncompressed P-256 point, got %d bytes", publicKeySize, len(b))
+	}
+	k, err := ecdh.P256().NewPublicKey(b)
+	if err != nil {
+		return nil, errors.New("not a point on P-256")
+	}
+	return k, nil
+}
+
+// ParsePrivateKey parses an encoded private key. Its errors never quote the
+// key.
+func ParsePrivateKey(s string) (*ecdh.PrivateKey, error) {
+	b, err := encoding.DecodeString(s)
+	if err != nil {
+		return nil, errors.New("not unpadded base64url")
+	}
+	if len(b) != privateKeySize {
+		return nil, fmt.Errorf("want a %d-byte P-256 scalar, got %d bytes", privateKeySize, len(b))
+	}
+	k, err := ecdh.P256().NewPrivateKey(b)
+	if err != nil {
+		return nil, errors.New("not a valid P-256 scalar")
+	}
+	return k, nil
+}
+
+// ErrMismatch is returned by CheckPair when the private key's public key is
+// not the given public key.
+var ErrMismatch = errors.New("private key does not belong to the public key")
+
+// CheckPair reports whether private is the private key of public, by
+// deriving the public point from private and comparing.
+func CheckPair(public *ecdh.PublicKey, private *ecdh.PrivateKey) error {
+	if !private.PublicKey().Equal(public) {
+		return ErrMismatch
+	}
+	return nil
+}

internal/vapid/vapid_test.go

@@ -0,0 +1,92 @@
+package vapid
+
+import (
+	"encoding/base64"
+	"strings"
+	"testing"
+)
+
+func TestGenerateRoundTrips(t *testing.T) {
+	t.Parallel()
+	a, err := Generate()
+	if err != nil {
+		t.Fatal(err)
+	}
+	b, err := Generate()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if a == b {
+		t.Fatal("two generated key pairs are equal")
+	}
+	// 65 and 32 bytes in unpadded base64url.
+	if len(a.PublicKey) != 87 || len(a.PrivateKey) != 43 {
+		t.Errorf("key lengths = %d, %d; want 87, 43", len(a.PublicKey), len(a.PrivateKey))
+	}
+	pub, err := ParsePublicKey(a.PublicKey)
+	if err != nil {
+		t.Fatal(err)
+	}
+	priv, err := ParsePrivateKey(a.PrivateKey)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := CheckPair(pub, priv); err != nil {
+		t.Errorf("CheckPair of a generated pair: %v", err)
+	}
+	other, err := ParsePrivateKey(b.PrivateKey)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := CheckPair(pub, other); err != ErrMismatch {
+		t.Errorf("CheckPair of mismatched keys = %v, want ErrMismatch", err)
+	}
+}
+
+func TestParseRejectsMalformedKeys(t *testing.T) {
+	t.Parallel()
+	pair, err := Generate()
+	if err != nil {
+		t.Fatal(err)
+	}
+	raw := func(b []byte) string { return base64.RawURLEncoding.EncodeToString(b) }
+	compressed, _ := base64.RawURLEncoding.DecodeString(pair.PublicKey)
+	compressed = append([]byte{0x02}, compressed[1:33]...)
+	offCurve := make([]byte, 65)
+	offCurve[0] = 0x04
+	offCurve[64] = 1
+	order := []byte{ // the P-256 group order n, not a valid scalar
+		0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xbc, 0xe6, 0xfa, 0xad, 0xa7, 0x17, 0x9e, 0x84, 0xf3, 0xb9, 0xca, 0xc2, 0xfc, 0x63, 0x25, 0x51,
+	}
+
+	for name, s := range map[string]string{
+		"empty":          "",
+		"padded":         pair.PublicKey + "=",
+		"standard alpha": strings.NewReplacer("-", "+", "_", "/").Replace(pair.PublicKey) + "+/",
+		"compressed":     raw(compressed),
+		"off curve":      raw(offCurve),
+		"private key":    pair.PrivateKey,
+	} {
+		if _, err := ParsePublicKey(s); err == nil {
+			t.Errorf("ParsePublicKey(%s) succeeded", name)
+		}
+	}
+	for name, s := range map[string]string{
+		"empty":      "",
+		"padded":     pair.PrivateKey + "=",
+		"PEM":        "-----BEGIN EC PRIVATE KEY-----",
+		"zero":       raw(make([]byte, 32)),
+		"group size": raw(order),
+		"public key": pair.PublicKey,
+	} {
+		_, err := ParsePrivateKey(s)
+		if err == nil {
+			t.Errorf("ParsePrivateKey(%s) succeeded", name)
+			continue
+		}
+		if s != "" && strings.Contains(err.Error(), s) {
+			t.Errorf("ParsePrivateKey(%s) error quotes the key: %v", name, err)
+		}
+	}
+}

migrations/queries/notifications.sql

@@ -0,0 +1,58 @@
+-- name: GetNotificationPref :one
+SELECT * FROM notification_prefs
+WHERE event = ?;
+
+-- name: InsertNotification :execrows
+-- Stores a pending notification for one channel, due at once. A row already
+-- stored for the event key and channel, in any status, is left unchanged and
+-- no row is inserted.
+INSERT INTO notification_outbox (
+	id, event_key, channel, payload, status, attempts, next_attempt_at, created_at, updated_at
+) VALUES (
+	sqlc.arg(id), sqlc.arg(event_key), sqlc.arg(channel), sqlc.arg(payload), 'pending', 0, sqlc.arg(next_attempt_at), sqlc.arg(now), sqlc.arg(now)
+)
+ON CONFLICT (event_key, channel) DO NOTHING;
+
+-- name: ClaimDueNotification :one
+-- Leases the pending notification due longest ago by moving its
+-- next_attempt_at to lease_until, and returns it. A claimed row is not due
+-- again until the lease ends, so no other claim takes it while it is being
+-- delivered. Returns sql.ErrNoRows when none is due.
+UPDATE notification_outbox
+SET next_attempt_at = sqlc.arg(lease_until), updated_at = sqlc.arg(now)
+WHERE id = (
+	SELECT id FROM notification_outbox
+	WHERE status = 'pending' AND next_attempt_at <= sqlc.arg(now)
+	ORDER BY next_attempt_at, id
+	LIMIT 1
+)
+RETURNING *;
+
+-- name: MarkNotificationSent :execrows
+-- Records a delivered notification; updated_at is when it was sent. The
+-- lease must still be the claim's.
+UPDATE notification_outbox
+SET status = 'sent', attempts = attempts + 1, next_attempt_at = NULL, updated_at = sqlc.arg(now)
+WHERE id = sqlc.arg(id) AND status = 'pending' AND next_attempt_at = sqlc.arg(lease_until);
+
+-- name: RetryNotification :execrows
+-- Records a failed delivery and when to try again. The lease must still be
+-- the claim's.
+UPDATE notification_outbox
+SET attempts = attempts + 1, next_attempt_at = sqlc.arg(next_attempt_at), last_error = sqlc.arg(last_error), updated_at = sqlc.arg(now)
+WHERE id = sqlc.arg(id) AND status = 'pending' AND next_attempt_at = sqlc.arg(lease_until);
+
+-- name: FailNotification :execrows
+-- Gives up on a notification. attempts counts the delivery attempt that
+-- failed, if one was made. The lease must still be the claim's.
+UPDATE notification_outbox
+SET status = 'failed', attempts = attempts + sqlc.arg(attempted), next_attempt_at = NULL, last_error = sqlc.arg(last_error), updated_at = sqlc.arg(now)
+WHERE id = sqlc.arg(id) AND status = 'pending' AND next_attempt_at = sqlc.arg(lease_until);
+
+-- name: NextNotificationDue :one
+-- Returns when the next pending notification is due. Returns sql.ErrNoRows
+-- when none is pending.
+SELECT next_attempt_at FROM notification_outbox
+WHERE status = 'pending'
+ORDER BY next_attempt_at
+LIMIT 1;

migrations/queries/push_subscriptions.sql

@@ -0,0 +1,20 @@
+-- name: UpsertPushSubscription :one
+-- Stores a browser's push subscription, keyed by its endpoint. Subscribing
+-- an endpoint already stored replaces its keys and user agent and clears
+-- its failure count, keeping its id, created_at and last_success_at.
+INSERT INTO push_subscriptions (
+	id, endpoint, p256dh, auth, user_agent, failure_count, created_at, updated_at
+) VALUES (
+	?, ?, ?, ?, ?, 0, ?, ?
+)
+ON CONFLICT (endpoint) DO UPDATE SET
+	p256dh = excluded.p256dh,
+	auth = excluded.auth,
+	user_agent = excluded.user_agent,
+	failure_count = 0,
+	updated_at = excluded.updated_at
+RETURNING *;
+
+-- name: DeletePushSubscription :execrows
+DELETE FROM push_subscriptions
+WHERE endpoint = ?;

web/src/push/notification.test.ts

@@ -0,0 +1,231 @@
+import { describe, expect, it, vi } from 'vitest'
+import {
+  APP_BADGE,
+  APP_ICON,
+  GENERIC_NOTICE,
+  appPath,
+  clickPath,
+  openNotification,
+  parsePushPayload,
+  planClick,
+  showPush,
+  type ClickWindow,
+} from './notification.ts'
+
+const origin = 'https://mealquest.example'
+
+describe('appPath', () => {
+  it('keeps a same-origin path with its query and fragment', () => {
+    expect(appPath('/plan/shopping?week=2026-10-05#tuesday', origin)).toBe('/plan/shopping?week=2026-10-05#tuesday')
+  })
+
+  it.each([
+    'https://evil.example/plan',
+    '//evil.example/plan',
+    '/\\evil.example/plan',
+    'javascript:alert(1)',
+    'plan',
+    '',
+  ])('refuses %s', (raw) => {
+    expect(appPath(raw, origin)).toBeNull()
+  })
+
+  it('resolves dot segments and keeps the result on origin', () => {
+    expect(appPath('/plan/../discover', origin)).toBe('/discover')
+  })
+
+  // Each of these starts with a single / but resolves to a path starting with
+  // //, which a browser reads as another host.
+  it.each([
+    '/..//evil.example/path',
+    '/plan/..//evil.example/path',
+    '/..\\\\evil.example/path',
+    '/./\\evil.example',
+    '/.\\/evil.example',
+    '/%2e%2e//evil.example/path',
+    '/.\t.//evil.example/path',
+    '/..\n//evil.example',
+  ])('refuses %j, which resolves to a protocol-relative path', (raw) => {
+    expect(appPath(raw, origin)).toBeNull()
+  })
+})
+
+describe('parsePushPayload', () => {
+  it('reads title, body, tag and url', () => {
+    const text = JSON.stringify({ title: 'Plan ready', body: 'Your Draft board is ready.', tag: 'plan_ready', url: '/plan' })
+    expect(parsePushPayload(text, origin)).toEqual({
+      notice: { title: 'Plan ready', body: 'Your Draft board is ready.', tag: 'plan_ready', url: '/plan' },
+      problem: null,
+    })
+  })
+
+  it('opens home with an empty body and no tag when only a title is sent', () => {
+    expect(parsePushPayload(JSON.stringify({ title: 'Hi' }), origin)).toEqual({
+      notice: { title: 'Hi', body: '', url: '/' },
+      problem: null,
+    })
+  })
+
+  it('ignores fields it does not know', () => {
+    const parsed = parsePushPayload(JSON.stringify({ title: 'Hi', event: 'plan_ready' }), origin)
+    expect(parsed.problem).toBeNull()
+    expect(parsed.notice).toEqual({ title: 'Hi', body: '', url: '/' })
+  })
+
+  it.each([
+    [null, 'push message has no payload'],
+    ['', 'push message has no payload'],
+    ['\u0000ÿ not json', 'push payload is not JSON'],
+    ['[1,2]', 'push payload is not a JSON object'],
+    ['null', 'push payload is not a JSON object'],
+    ['{"body":"no title"}', 'push payload has no title'],
+    ['{"title":"   "}', 'push payload has no title'],
+    ['{"title":42}', 'push payload has no title'],
+    ['{"title":"Hi","body":7}', 'push payload body is not a string'],
+    ['{"title":"Hi","tag":""}', 'push payload tag is not a non-empty string'],
+    ['{"title":"Hi","url":"https://evil.example/"}', 'push payload url is not a same-origin path'],
+    ['{"title":"Hi","url":5}', 'push payload url is not a same-origin path'],
+  ])('shows the generic notice for %j', (text, problem) => {
+    expect(parsePushPayload(text, origin)).toEqual({ notice: GENERIC_NOTICE, problem })
+  })
+})
+
+describe('showPush', () => {
+  it('shows the payload with the app icon and badge, its tag and its url as data', async () => {
+    const registration = { showNotification: vi.fn(async () => {}) }
+    const warn = vi.fn()
+    await showPush(
+      JSON.stringify({ title: 'Supply run ready', body: 'Time to shop.', tag: 'list_ready', url: '/plan/shopping' }),
+      registration,
+      origin,
+      warn,
+    )
+    expect(registration.showNotification).toHaveBeenCalledWith('Supply run ready', {
+      body: 'Time to shop.',
+      tag: 'list_ready',
+      icon: APP_ICON,
+      badge: APP_BADGE,
+      data: { url: '/plan/shopping' },
+    })
+    expect(warn).not.toHaveBeenCalled()
+  })
+
+  it('shows the generic notification for a malformed payload and logs why, without throwing', async () => {
+    const registration = { showNotification: vi.fn(async () => {}) }
+    const warn = vi.fn()
+    await expect(showPush('{not json', registration, origin, warn)).resolves.toBeUndefined()
+    expect(registration.showNotification).toHaveBeenCalledWith('MealQuest', {
+      body: GENERIC_NOTICE.body,
+      icon: APP_ICON,
+      badge: APP_BADGE,
+      data: { url: '/' },
+    })
+    expect(warn).toHaveBeenCalledWith('MealQuest: push payload is not JSON; showing the generic notification')
+  })
+})
+
+describe('clickPath', () => {
+  it('opens the url the notification carries', () => {
+    expect(clickPath({ url: '/discover' }, origin)).toBe('/discover')
+  })
+
+  it.each([undefined, null, 'x', {}, { url: 'https://evil.example/' }])('opens home for data %j', (data) => {
+    expect(clickPath(data, origin)).toBe('/')
+  })
+})
+
+describe('planClick', () => {
+  it('refuses a path that resolves off origin', () => {
+    expect(() => planClick([], '//evil.example/path', origin)).toThrow(/resolves off origin/)
+  })
+
+  const at = (path: string, focused = false) => ({ url: origin + path, focused })
+
+  it('opens a new window when no MealQuest window is open', () => {
+    expect(planClick([], '/plan', origin)).toEqual({ action: 'open', url: `${origin}/plan` })
+  })
+
+  it('ignores windows on another origin', () => {
+    const other = { url: 'https://other.example/plan', focused: true }
+    expect(planClick([other], '/plan', origin)).toEqual({ action: 'open', url: `${origin}/plan` })
+  })
+
+  it('focuses the focused MealQuest window and navigates it', () => {
+    const first = at('/')
+    const focused = at('/discover', true)
+    expect(planClick([first, focused], '/plan', origin)).toEqual({
+      action: 'focus',
+      window: focused,
+      url: `${origin}/plan`,
+      navigate: true,
+    })
+  })
+
+  it('focuses the first MealQuest window when none is focused', () => {
+    const first = at('/')
+    expect(planClick([first, at('/discover')], '/plan', origin)).toMatchObject({ action: 'focus', window: first })
+  })
+
+  it('does not reload a window already at the url', () => {
+    expect(planClick([at('/plan')], '/plan', origin)).toMatchObject({ action: 'focus', navigate: false })
+  })
+})
+
+describe('openNotification', () => {
+  function window(path: string, focused = false) {
+    return {
+      url: origin + path,
+      focused,
+      focus: vi.fn(async () => {}),
+      navigate: vi.fn(async () => {}),
+    } satisfies ClickWindow
+  }
+
+  function clients(windows: ClickWindow[]) {
+    return { matchAll: vi.fn(async () => windows), openWindow: vi.fn(async () => null) }
+  }
+
+  it('focuses an open window, then navigates it to the url', async () => {
+    const win = window('/', true)
+    const all = clients([win])
+    await openNotification({ url: '/plan/shopping' }, all, origin)
+    expect(all.matchAll).toHaveBeenCalledWith({ type: 'window' })
+    expect(win.focus).toHaveBeenCalled()
+    expect(win.navigate).toHaveBeenCalledWith(`${origin}/plan/shopping`)
+    expect(win.focus.mock.invocationCallOrder[0]).toBeLessThan(win.navigate.mock.invocationCallOrder[0]!)
+    expect(all.openWindow).not.toHaveBeenCalled()
+  })
+
+  it('opens a new window at the url when none is open', async () => {
+    const all = clients([])
+    await openNotification({ url: '/discover' }, all, origin)
+    expect(all.openWindow).toHaveBeenCalledWith(`${origin}/discover`)
+  })
+
+  it('never opens a url off origin, even from tampered data', async () => {
+    const all = clients([])
+    await openNotification({ url: 'https://evil.example/' }, all, origin)
+    expect(all.openWindow).toHaveBeenCalledWith(`${origin}/`)
+  })
+
+  it.each(['/..//evil.example/path', '/..\\\\evil.example/path', '/%2e%2e//evil.example/path', '/.\t.//evil.example/path'])(
+    'never leaves origin for %j, which resolves to a protocol-relative path',
+    async (url) => {
+      const win = window('/plan', true)
+      const all = clients([win])
+      await openNotification({ url }, all, origin)
+      expect(win.navigate).toHaveBeenCalledWith(`${origin}/`)
+      expect(all.openWindow).not.toHaveBeenCalled()
+
+      const none = clients([])
+      await openNotification({ url }, none, origin)
+      expect(none.openWindow).toHaveBeenCalledWith(`${origin}/`)
+    },
+  )
+
+  it('still opens an internal path that uses dot segments', async () => {
+    const all = clients([])
+    await openNotification({ url: '/plan/../discover' }, all, origin)
+    expect(all.openWindow).toHaveBeenCalledWith(`${origin}/discover`)
+  })
+})

web/src/push/notification.ts

@@ -0,0 +1,174 @@
+// Web Push notifications as the service worker shows them, and where a tap on
+// one takes the household. The worker's push and notificationclick listeners
+// (src/sw.ts) only adapt these to the worker's globals, so every decision runs
+// under test without a real ServiceWorkerGlobalScope. This file is checked
+// with both the DOM and the WebWorker libraries, so it names only the narrow
+// shapes it uses.
+
+// APP_ICON and APP_BADGE are the app icon from the web manifest.
+export const APP_ICON = '/icons/icon-192.png'
+export const APP_BADGE = '/icons/icon-192.png'
+
+// PushNotice is a notification to show: its title, body and tag, and the
+// same-origin path a tap opens.
+export type PushNotice = { title: string; body: string; tag?: string; url: string }
+
+// GENERIC_NOTICE is shown for a push whose payload is not a notice: the
+// household still learns that MealQuest has something for them.
+export const GENERIC_NOTICE: PushNotice = {
+  title: 'MealQuest',
+  body: "There's something new in MealQuest.",
+  url: '/',
+}
+
+// ParsedPush is the notice to show for a push, and why its payload was not
+// used, when it was not.
+export type ParsedPush = { notice: PushNotice; problem: string | null }
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === 'object' && value !== null && !Array.isArray(value)
+}
+
+// appPath returns raw as a path on origin (path, query and fragment), or null
+// when raw is not a path-absolute URL that stays on origin. A payload never
+// sends the household to another site. The path is checked after the parser
+// has resolved it: dot segments (also as %2e), backslashes and stripped tabs
+// and newlines can all turn an innocent-looking path into one starting with
+// //, which a browser would read as another host.
+export function appPath(raw: string, origin: string): string | null {
+  if (!raw.startsWith('/') || raw.startsWith('//')) return null
+  let url: URL
+  try {
+    url = new URL(raw, origin)
+  } catch {
+    return null
+  }
+  if (url.origin !== origin || url.pathname.startsWith('//')) return null
+  return url.pathname + url.search + url.hash
+}
+
+// parsePushPayload reads a push message's payload, which may be any bytes:
+// a JSON object with a non-empty string title, and optionally a string body,
+// a non-empty string tag and a url that is a same-origin path. Other fields
+// are ignored. Anything else — no payload, not JSON, a missing title, a
+// field of the wrong type, a url off origin — is shown as GENERIC_NOTICE,
+// with the problem for the worker to log. It never throws.
+export function parsePushPayload(text: string | null, origin: string): ParsedPush {
+  const generic = (problem: string): ParsedPush => ({ notice: GENERIC_NOTICE, problem })
+  if (text === null || text === '') return generic('push message has no payload')
+  let payload: unknown
+  try {
+    payload = JSON.parse(text)
+  } catch {
+    return generic('push payload is not JSON')
+  }
+  if (!isRecord(payload)) return generic('push payload is not a JSON object')
+  const { title, body, tag, url } = payload
+  if (typeof title !== 'string' || title.trim() === '') return generic('push payload has no title')
+  if (body !== undefined && typeof body !== 'string') return generic('push payload body is not a string')
+  if (tag !== undefined && (typeof tag !== 'string' || tag === '')) {
+    return generic('push payload tag is not a non-empty string')
+  }
+  let path = '/'
+  if (url !== undefined) {
+    const safe = typeof url === 'string' ? appPath(url, origin) : null
+    if (safe === null) return generic('push payload url is not a same-origin path')
+    path = safe
+  }
+  const notice: PushNotice = { title, body: body ?? '', url: path }
+  if (tag !== undefined) notice.tag = tag
+  return { notice, problem: null }
+}
+
+// NoticeData is the data a shown notification carries for its click.
+export type NoticeData = { url: string }
+
+// notificationOptions is what showNotification is given for notice: its body
+// and tag, the app icon and badge, and the path to open as its data.
+export function notificationOptions(notice: PushNotice): NotificationOptions & { data: NoticeData } {
+  const options: NotificationOptions & { data: NoticeData } = {
+    body: notice.body,
+    icon: APP_ICON,
+    badge: APP_BADGE,
+    data: { url: notice.url },
+  }
+  if (notice.tag !== undefined) options.tag = notice.tag
+  return options
+}
+
+export type NotificationShower = {
+  showNotification(title: string, options: NotificationOptions): Promise<void>
+}
+
+// showPush shows the notification for a push message's payload text,
+// reporting through warn why a payload was not used.
+export function showPush(
+  text: string | null,
+  registration: NotificationShower,
+  origin: string,
+  warn: (message: string) => void,
+): Promise<void> {
+  const { notice, problem } = parsePushPayload(text, origin)
+  if (problem !== null) warn(`MealQuest: ${problem}; showing the generic notification`)
+  return registration.showNotification(notice.title, notificationOptions(notice))
+}
+
+// clickPath is the same-origin path a tapped notification opens: the url in
+// its data, which showPush put there, or the app's home when the data is not
+// ours (a notification shown by an older worker).
+export function clickPath(data: unknown, origin: string): string {
+  if (isRecord(data) && typeof data.url === 'string') {
+    const path = appPath(data.url, origin)
+    if (path !== null) return path
+  }
+  return '/'
+}
+
+// AppWindow is the part of a window client a click reads.
+export type AppWindow = { url: string; focused: boolean }
+
+// ClickPlan is what a notification tap does: focus an open MealQuest window
+// and navigate it to url, or open a new window at url. url is absolute.
+export type ClickPlan<W> = { action: 'focus'; window: W; url: string; navigate: boolean } | { action: 'open'; url: string }
+
+// planClick decides a tap on a notification that opens path: the focused
+// MealQuest window if there is one, else the first open one, navigated to
+// path unless it is already there; with none open, a new window. A path that
+// resolves off origin is an error: a tap never leaves MealQuest.
+export function planClick<W extends AppWindow>(windows: readonly W[], path: string, origin: string): ClickPlan<W> {
+  const resolved = new URL(path, origin)
+  if (resolved.origin !== origin) {
+    throw new Error(`MealQuest: notification path ${JSON.stringify(path)} resolves off origin to ${resolved.origin}`)
+  }
+  const url = resolved.href
+  const ours = windows.filter((w) => URL.canParse(w.url) && new URL(w.url).origin === origin)
+  const target = ours.find((w) => w.focused) ?? ours[0]
+  if (target === undefined) return { action: 'open', url }
+  return { action: 'focus', window: target, url, navigate: target.url !== url }
+}
+
+export type ClickWindow = AppWindow & {
+  focus(): Promise<unknown>
+  navigate(url: string): Promise<unknown>
+}
+
+export type ClickClients<W extends ClickWindow> = {
+  matchAll(options: { type: 'window' }): Promise<readonly W[]>
+  openWindow(url: string): Promise<unknown>
+}
+
+// openNotification carries out a tap on a notification with data: focus
+// first, while the tap still allows it, then navigate.
+export async function openNotification<W extends ClickWindow>(
+  data: unknown,
+  clients: ClickClients<W>,
+  origin: string,
+): Promise<void> {
+  const plan = planClick(await clients.matchAll({ type: 'window' }), clickPath(data, origin), origin)
+  if (plan.action === 'open') {
+    await clients.openWindow(plan.url)
+    return
+  }
+  await plan.window.focus()
+  if (plan.navigate) await plan.window.navigate(plan.url)
+}

web/src/push/subscribe.test.ts

@@ -0,0 +1,308 @@
+import { describe, expect, it, vi } from 'vitest'
+import { ApiError, type ApiRequest } from '../api/index.ts'
+import {
+  SUBSCRIPTIONS_PATH,
+  VAPID_PUBLIC_KEY_PATH,
+  decodeVapidKey,
+  encodeBase64url,
+  PermissionGestureError,
+  subscribePush,
+  subscriptionBody,
+  unsubscribePush,
+  type BrowserPushSubscription,
+  type PushEnvironment,
+} from './subscribe.ts'
+
+function bytes(length: number, first: number): Uint8Array<ArrayBuffer> {
+  const out = new Uint8Array(new ArrayBuffer(length))
+  for (let i = 0; i < length; i++) out[i] = (first + i) % 256
+  return out
+}
+
+const vapidKey = bytes(65, 4)
+const vapidKeyText = encodeBase64url(vapidKey.buffer)
+const p256dh = bytes(65, 4).buffer
+const auth = bytes(16, 200).buffer
+const endpoint = 'https://push.example/send/abc'
+
+function subscription(key: ArrayBuffer | null = vapidKey.buffer, at = endpoint) {
+  return {
+    endpoint: at,
+    options: { applicationServerKey: key },
+    getKey: (name: 'p256dh' | 'auth') => (name === 'p256dh' ? p256dh : auth),
+    unsubscribe: vi.fn(async () => true),
+  } satisfies BrowserPushSubscription
+}
+
+type Setup = {
+  permission?: NotificationPermission
+  answer?: NotificationPermission
+  active?: boolean
+  current?: BrowserPushSubscription | null
+  registered?: boolean
+  subscribeError?: unknown
+}
+
+function setup({
+  permission = 'default',
+  answer = 'granted',
+  active = true,
+  current = null,
+  registered = true,
+  subscribeError,
+}: Setup = {}) {
+  const created = subscription()
+  const pushManager = {
+    getSubscription: vi.fn(async () => current),
+    subscribe: vi.fn(async () => {
+      if (subscribeError !== undefined) throw subscribeError
+      return created
+    }),
+  }
+  const notification = { permission, requestPermission: vi.fn(async () => answer) }
+  const env: PushEnvironment = {
+    serviceWorker: { getRegistration: vi.fn(async () => (registered ? { pushManager } : undefined)) },
+    pushManager: true,
+    notification,
+    userActivation: { isActive: active },
+    userAgent: 'Mozilla/5.0 Test',
+  }
+  const calls: { path: string; request?: ApiRequest }[] = []
+  const api = {
+    apiFetch: vi.fn(async (path: string, request?: ApiRequest) => {
+      calls.push({ path, request })
+      if (path === VAPID_PUBLIC_KEY_PATH) return { public_key: vapidKeyText }
+      return undefined
+    }) as <T>(path: string, request?: ApiRequest) => Promise<T>,
+  }
+  return { env, api, calls, pushManager, notification, created }
+}
+
+describe('decodeVapidKey', () => {
+  it('decodes the unpadded base64url point', () => {
+    expect(decodeVapidKey(vapidKeyText)).toEqual(vapidKey)
+  })
+
+  it.each(['', 'abc=', 'not base64!', encodeBase64url(bytes(64, 4).buffer), encodeBase64url(bytes(65, 2).buffer)])(
+    'refuses %j',
+    (key) => {
+      expect(() => decodeVapidKey(key)).toThrow(/65-byte uncompressed P-256 point/)
+    },
+  )
+})
+
+describe('subscriptionBody', () => {
+  it('sends exactly the endpoint, the keys in unpadded base64url and the user agent', () => {
+    const body = subscriptionBody(subscription(), 'Mozilla/5.0 Test')
+    expect(body).toEqual({
+      endpoint,
+      keys: { p256dh: encodeBase64url(p256dh), auth: encodeBase64url(auth) },
+      user_agent: 'Mozilla/5.0 Test',
+    })
+    expect(body.keys.auth).toMatch(/^[A-Za-z0-9_-]{22}$/)
+    expect(JSON.stringify(body)).not.toContain('expirationTime')
+  })
+
+  it.each(['', '   ', 'x'.repeat(513)])('leaves out a blank or too-long user agent', (userAgent) => {
+    expect(subscriptionBody(subscription(), userAgent)).not.toHaveProperty('user_agent')
+  })
+
+  it('refuses a subscription without keys', () => {
+    const keyless = { ...subscription(), getKey: () => null }
+    expect(() => subscriptionBody(keyless, 'ua')).toThrow(/without its p256dh and auth keys/)
+  })
+})
+
+describe('subscribePush', () => {
+  it.each([
+    ['serviceWorker', { serviceWorker: undefined }],
+    ['PushManager', { pushManager: false }],
+    ['Notification', { notification: undefined }],
+  ])('answers unsupported without %s, asking nothing', async (_, missing) => {
+    const { env, api, notification } = setup()
+    expect(await subscribePush(api, { ...env, ...missing })).toBe('unsupported')
+    expect(notification.requestPermission).not.toHaveBeenCalled()
+    expect(api.apiFetch).not.toHaveBeenCalled()
+  })
+
+  it('asks for permission during a tap, subscribes with the server key and stores the subscription', async () => {
+    const { env, api, calls, pushManager, notification } = setup()
+    expect(await subscribePush(api, env)).toBe('subscribed')
+    expect(notification.requestPermission).toHaveBeenCalledTimes(1)
+    expect(pushManager.subscribe).toHaveBeenCalledWith({ userVisibleOnly: true, applicationServerKey: vapidKey })
+    expect(calls).toEqual([
+      { path: VAPID_PUBLIC_KEY_PATH, request: undefined },
+      {
+        path: SUBSCRIPTIONS_PATH,
+        request: {
+          method: 'POST',
+          body: {
+            endpoint,
+            keys: { p256dh: encodeBase64url(p256dh), auth: encodeBase64url(auth) },
+            user_agent: 'Mozilla/5.0 Test',
+          },
+        },
+      },
+    ])
+  })
+
+  it('asks for permission before awaiting anything, so the tap still counts', async () => {
+    const { env, api, notification } = setup()
+    const pending = subscribePush(api, env)
+    expect(notification.requestPermission).toHaveBeenCalledTimes(1)
+    expect(api.apiFetch).not.toHaveBeenCalled()
+    await pending
+  })
+
+  it('refuses to ask for permission outside a tap', async () => {
+    const { env, api, notification } = setup({ active: false })
+    const error = await subscribePush(api, env).catch((e: unknown) => e)
+    expect(error).toBeInstanceOf(PermissionGestureError)
+    expect(error).toMatchObject({ reason: 'inactive', message: expect.stringMatching(/only be asked for from a tap/) })
+    expect(notification.requestPermission).not.toHaveBeenCalled()
+    expect(api.apiFetch).not.toHaveBeenCalled()
+  })
+
+  it('refuses to ask for permission where the browser cannot say whether a tap is active', async () => {
+    const { env, api, notification } = setup()
+    const error = await subscribePush(api, { ...env, userActivation: undefined }).catch((e: unknown) => e)
+    expect(error).toBeInstanceOf(PermissionGestureError)
+    expect(error).toMatchObject({ reason: 'unobservable', message: expect.stringMatching(/no navigator.userActivation/) })
+    expect(notification.requestPermission).not.toHaveBeenCalled()
+    expect(api.apiFetch).not.toHaveBeenCalled()
+  })
+
+  it('does not need to observe a tap once permission is granted', async () => {
+    const { env, api, notification } = setup({ permission: 'granted' })
+    expect(await subscribePush(api, { ...env, userActivation: undefined })).toBe('subscribed')
+    expect(notification.requestPermission).not.toHaveBeenCalled()
+  })
+
+  it('does not ask again once permission is granted, even outside a tap', async () => {
+    const { env, api, notification } = setup({ permission: 'granted', active: false })
+    expect(await subscribePush(api, env)).toBe('subscribed')
+    expect(notification.requestPermission).not.toHaveBeenCalled()
+  })
+
+  it('reports a permission denied earlier without asking or subscribing', async () => {
+    const { env, api, notification, pushManager } = setup({ permission: 'denied' })
+    expect(await subscribePush(api, env)).toBe('denied')
+    expect(notification.requestPermission).not.toHaveBeenCalled()
+    expect(pushManager.subscribe).not.toHaveBeenCalled()
+    expect(api.apiFetch).not.toHaveBeenCalled()
+  })
+
+  it('reports a permission denied when asked, without subscribing', async () => {
+    const { env, api, pushManager } = setup({ answer: 'denied' })
+    expect(await subscribePush(api, env)).toBe('denied')
+    expect(pushManager.subscribe).not.toHaveBeenCalled()
+    expect(api.apiFetch).not.toHaveBeenCalled()
+  })
+
+  it('reports a dismissed prompt', async () => {
+    const { env, api, pushManager } = setup({ answer: 'default' })
+    expect(await subscribePush(api, env)).toBe('dismissed')
+    expect(pushManager.subscribe).not.toHaveBeenCalled()
+  })
+
+  it('reports denied when the browser refuses the subscription for permission', async () => {
+    const { env, api, calls } = setup({ subscribeError: new DOMException('Registration failed - permission denied', 'NotAllowedError') })
+    expect(await subscribePush(api, env)).toBe('denied')
+    expect(calls.map((c) => c.path)).toEqual([VAPID_PUBLIC_KEY_PATH])
+  })
+
+  it('rejects with an Error, not a raw DOMException, when the browser cannot subscribe', async () => {
+    const cause = new DOMException('push service not available', 'AbortError')
+    const { env, api } = setup({ subscribeError: cause })
+    const error = await subscribePush(api, env).catch((e: unknown) => e)
+    expect(error).not.toBeInstanceOf(DOMException)
+    expect(error).toBeInstanceOf(Error)
+    expect((error as Error).message).toBe('Web Push: the browser could not subscribe: push service not available')
+    expect((error as Error).cause).toBe(cause)
+  })
+
+  it('rejects when no service worker is registered', async () => {
+    const { env, api } = setup({ registered: false })
+    await expect(subscribePush(api, env)).rejects.toThrow(/no service worker is registered/)
+  })
+
+  it('stores an existing subscription made with the same key again, without resubscribing', async () => {
+    const current = subscription()
+    const { env, api, calls, pushManager } = setup({ permission: 'granted', current })
+    expect(await subscribePush(api, env)).toBe('subscribed')
+    expect(pushManager.subscribe).not.toHaveBeenCalled()
+    expect(current.unsubscribe).not.toHaveBeenCalled()
+    expect(calls.map((c) => c.request?.method ?? 'GET')).toEqual(['GET', 'POST'])
+  })
+
+  it('replaces a subscription made with an older key', async () => {
+    const old = subscription(bytes(65, 9).buffer, 'https://push.example/send/old')
+    const { env, api, calls, pushManager } = setup({ permission: 'granted', current: old })
+    expect(await subscribePush(api, env)).toBe('subscribed')
+    expect(old.unsubscribe).toHaveBeenCalled()
+    expect(pushManager.subscribe).toHaveBeenCalled()
+    expect(calls.map((c) => [c.request?.method ?? 'GET', c.request?.body])).toEqual([
+      ['GET', undefined],
+      ['DELETE', { endpoint: 'https://push.example/send/old' }],
+      ['POST', expect.objectContaining({ endpoint })],
+    ])
+  })
+
+  it('passes on an API failure storing the subscription', async () => {
+    const { env, api } = setup()
+    const refused = new ApiError(400, 'invalid_subscription', 'endpoint: want an absolute https:// URL', false)
+    vi.mocked(api.apiFetch).mockImplementation(async (path: string) => {
+      if (path === VAPID_PUBLIC_KEY_PATH) return { public_key: vapidKeyText } as never
+      throw refused
+    })
+    await expect(subscribePush(api, env)).rejects.toBe(refused)
+  })
+
+  it('rejects a VAPID key response without a public_key', async () => {
+    const { env, api } = setup()
+    vi.mocked(api.apiFetch).mockResolvedValue({} as never)
+    await expect(subscribePush(api, env)).rejects.toThrow(`GET ${VAPID_PUBLIC_KEY_PATH}: response has no public_key`)
+  })
+})
+
+describe('unsubscribePush', () => {
+  it('deletes the subscription on the server, then in the browser', async () => {
+    const current = subscription()
+    const { env, api, calls } = setup({ current })
+    expect(await unsubscribePush(api, env)).toBe('unsubscribed')
+    expect(calls).toEqual([{ path: SUBSCRIPTIONS_PATH, request: { method: 'DELETE', body: { endpoint } } }])
+    expect(current.unsubscribe).toHaveBeenCalled()
+  })
+
+  it('answers not-subscribed without calling the server when there is no subscription', async () => {
+    const { env, api } = setup({ current: null })
+    expect(await unsubscribePush(api, env)).toBe('not-subscribed')
+    expect(api.apiFetch).not.toHaveBeenCalled()
+  })
+
+  it('answers not-subscribed when no service worker is registered', async () => {
+    const { env, api } = setup({ registered: false })
+    expect(await unsubscribePush(api, env)).toBe('not-subscribed')
+    expect(api.apiFetch).not.toHaveBeenCalled()
+  })
+
+  it('answers unsupported without Web Push', async () => {
+    const { env, api } = setup()
+    expect(await unsubscribePush(api, { ...env, pushManager: false })).toBe('unsupported')
+  })
+
+  it('keeps the browser subscribed when the server delete fails, so trying again works', async () => {
+    const current = subscription()
+    const { env, api } = setup({ current })
+    vi.mocked(api.apiFetch).mockRejectedValue(new TypeError('Failed to fetch'))
+    await expect(unsubscribePush(api, env)).rejects.toThrow('Failed to fetch')
+    expect(current.unsubscribe).not.toHaveBeenCalled()
+  })
+
+  it('rejects when the browser does not remove the subscription', async () => {
+    const current = subscription()
+    current.unsubscribe.mockResolvedValue(false)
+    const { env, api } = setup({ current })
+    await expect(unsubscribePush(api, env)).rejects.toThrow(/did not remove its push subscription/)
+  })
+})

web/src/push/subscribe.ts

@@ -0,0 +1,209 @@
+import type { ApiClient } from '../api/client.ts'
+import { isRecord } from '../api/errors.ts'
+
+export const VAPID_PUBLIC_KEY_PATH = '/api/v1/push/vapid-public-key'
+export const SUBSCRIPTIONS_PATH = '/api/v1/push/subscriptions'
+
+// MAX_USER_AGENT_BYTES is the server's limit on a subscription's user_agent
+// (internal/push MaxUserAgentBytes).
+export const MAX_USER_AGENT_BYTES = 512
+
+// SubscribePushResult is how turning on Web Push on this device ended:
+// subscribed, the browser's permission denied (now or earlier), the
+// permission prompt dismissed without an answer, or a browser without Web
+// Push. Any other failure rejects with an Error (an ApiError from the API).
+export type SubscribePushResult = 'subscribed' | 'denied' | 'dismissed' | 'unsupported'
+
+// UnsubscribePushResult is how turning off Web Push on this device ended:
+// its subscription removed from the browser and the server, no subscription
+// to remove, or a browser without Web Push. Any other failure rejects.
+export type UnsubscribePushResult = 'unsubscribed' | 'not-subscribed' | 'unsupported'
+
+// The parts of the browser's Push API this module uses.
+export type BrowserPushSubscription = {
+  readonly endpoint: string
+  readonly options: { readonly applicationServerKey: ArrayBuffer | null }
+  getKey(name: 'p256dh' | 'auth'): ArrayBuffer | null
+  unsubscribe(): Promise<boolean>
+}
+
+export type BrowserPushManager = {
+  getSubscription(): Promise<BrowserPushSubscription | null>
+  subscribe(options: { userVisibleOnly: boolean; applicationServerKey: Uint8Array<ArrayBuffer> }): Promise<BrowserPushSubscription>
+}
+
+// PushEnvironment is what the browser offers for Web Push. A field is
+// undefined (or pushManager false) where the browser lacks it.
+export type PushEnvironment = {
+  serviceWorker: { getRegistration(): Promise<{ readonly pushManager: BrowserPushManager } | undefined> } | undefined
+  pushManager: boolean
+  notification:
+    | { readonly permission: NotificationPermission; requestPermission(): Promise<NotificationPermission> }
+    | undefined
+  // Whether the page is handling a user gesture right now.
+  userActivation: { readonly isActive: boolean } | undefined
+  userAgent: string
+}
+
+// browserPushEnvironment reads the PushEnvironment from this window.
+export function browserPushEnvironment(): PushEnvironment {
+  return {
+    serviceWorker: 'serviceWorker' in navigator ? navigator.serviceWorker : undefined,
+    pushManager: 'PushManager' in window,
+    notification: 'Notification' in window ? Notification : undefined,
+    userActivation: 'userActivation' in navigator ? navigator.userActivation : undefined,
+    userAgent: navigator.userAgent,
+  }
+}
+
+type PushApi = Pick<ApiClient, 'apiFetch'>
+
+// PermissionGestureError is why subscribePush refused to ask for notification
+// permission: no tap is active right now ('inactive'), or the browser cannot
+// say whether one is ('unobservable', no navigator.userActivation).
+export class PermissionGestureError extends Error {
+  readonly reason: 'inactive' | 'unobservable'
+
+  constructor(reason: 'inactive' | 'unobservable') {
+    super(
+      reason === 'inactive'
+        ? 'subscribePush: notification permission can only be asked for from a tap on a button'
+        : 'subscribePush: this browser cannot report whether a tap is active (no navigator.userActivation), so notification permission is not asked for',
+    )
+    this.name = 'PermissionGestureError'
+    this.reason = reason
+  }
+}
+
+// encodeBase64url encodes bytes as unpadded base64url, as the server wants
+// subscription keys.
+export function encodeBase64url(bytes: ArrayBuffer): string {
+  let binary = ''
+  for (const byte of new Uint8Array(bytes)) binary += String.fromCharCode(byte)
+  return btoa(binary).replaceAll('+', '-').replaceAll('/', '_').replace(/=+$/, '')
+}
+
+// decodeVapidKey decodes the server's VAPID public key, unpadded base64url
+// of the 65-byte uncompressed P-256 point, into an applicationServerKey.
+export function decodeVapidKey(key: string): Uint8Array<ArrayBuffer> {
+  const problem = `GET ${VAPID_PUBLIC_KEY_PATH}: public_key is not the unpadded base64url of a 65-byte uncompressed P-256 point`
+  if (!/^[A-Za-z0-9_-]+$/.test(key) || key.length % 4 === 1) throw new Error(problem)
+  const binary = atob(key.replaceAll('-', '+').replaceAll('_', '/'))
+  const bytes = new Uint8Array(new ArrayBuffer(binary.length))
+  for (let i = 0; i < binary.length; i++) bytes[i] = binary.charCodeAt(i)
+  if (bytes.length !== 65 || bytes[0] !== 0x04) throw new Error(problem)
+  return bytes
+}
+
+function sameKey(current: ArrayBuffer | null, key: Uint8Array): boolean {
+  if (current === null || current.byteLength !== key.length) return false
+  const bytes = new Uint8Array(current)
+  return bytes.every((byte, i) => byte === key[i])
+}
+
+// SubscriptionBody is the POST /api/v1/push/subscriptions body. The server
+// refuses unknown fields and nulls, so it is built field by field rather
+// than from PushSubscription.toJSON(), whose expirationTime may be null.
+export type SubscriptionBody = { endpoint: string; keys: { p256dh: string; auth: string }; user_agent?: string }
+
+// subscriptionBody is the body that stores subscription. The user agent only
+// labels the device, so one that is blank or over the server's limit is left
+// out rather than sent to be refused.
+export function subscriptionBody(subscription: BrowserPushSubscription, userAgent: string): SubscriptionBody {
+  const p256dh = subscription.getKey('p256dh')
+  const auth = subscription.getKey('auth')
+  if (p256dh === null || auth === null) {
+    throw new Error('Web Push: the browser gave a subscription without its p256dh and auth keys')
+  }
+  const body: SubscriptionBody = {
+    endpoint: subscription.endpoint,
+    keys: { p256dh: encodeBase64url(p256dh), auth: encodeBase64url(auth) },
+  }
+  if (userAgent.trim() !== '' && new TextEncoder().encode(userAgent).length <= MAX_USER_AGENT_BYTES) {
+    body.user_agent = userAgent
+  }
+  return body
+}
+
+async function fetchVapidKey(api: PushApi): Promise<Uint8Array<ArrayBuffer>> {
+  const body = await api.apiFetch<unknown>(VAPID_PUBLIC_KEY_PATH)
+  if (!isRecord(body) || typeof body.public_key !== 'string') {
+    throw new Error(`GET ${VAPID_PUBLIC_KEY_PATH}: response has no public_key`)
+  }
+  return decodeVapidKey(body.public_key)
+}
+
+// removeSubscription deletes subscription on the server, then in the
+// browser. Deleting on the server first means a failure leaves both still
+// subscribed, so trying again finds the subscription and finishes the job.
+async function removeSubscription(api: PushApi, subscription: BrowserPushSubscription): Promise<void> {
+  await api.apiFetch<void>(SUBSCRIPTIONS_PATH, { method: 'DELETE', body: { endpoint: subscription.endpoint } })
+  if (!(await subscription.unsubscribe())) {
+    throw new Error('Web Push: the browser did not remove its push subscription')
+  }
+}
+
+function errorName(error: unknown): string | undefined {
+  return isRecord(error) && typeof error.name === 'string' ? error.name : undefined
+}
+
+// subscribePush turns on Web Push on this device. Call it only from the
+// household's tap on a button: when the browser has not yet been asked, it
+// asks for notification permission, which browsers allow only during a user
+// gesture, and it refuses to ask outside one — or where the browser cannot
+// say whether a gesture is active — with a PermissionGestureError. Permission
+// is asked before
+// anything is awaited so the gesture still counts. With permission, it
+// subscribes the browser with the server's VAPID public key — replacing a
+// subscription made with an older key — and stores the subscription on the
+// server. Subscribing again when already subscribed stores it again.
+export async function subscribePush(api: PushApi, env: PushEnvironment): Promise<SubscribePushResult> {
+  const { serviceWorker, notification } = env
+  if (serviceWorker === undefined || !env.pushManager || notification === undefined) return 'unsupported'
+
+  let permission = notification.permission
+  if (permission === 'default') {
+    if (env.userActivation === undefined) throw new PermissionGestureError('unobservable')
+    if (!env.userActivation.isActive) throw new PermissionGestureError('inactive')
+    permission = await notification.requestPermission()
+  }
+  if (permission === 'denied') return 'denied'
+  if (permission === 'default') return 'dismissed'
+
+  const found = await serviceWorker.getRegistration()
+  if (found === undefined) {
+    throw new Error('Web Push: no service worker is registered for this page, so it cannot receive notifications')
+  }
+  const { pushManager } = found
+  const key = await fetchVapidKey(api)
+  let subscription = await pushManager.getSubscription()
+  if (subscription !== null && !sameKey(subscription.options.applicationServerKey, key)) {
+    await removeSubscription(api, subscription)
+    subscription = null
+  }
+  if (subscription === null) {
+    try {
+      subscription = await pushManager.subscribe({ userVisibleOnly: true, applicationServerKey: key })
+    } catch (error) {
+      if (errorName(error) === 'NotAllowedError') return 'denied'
+      throw new Error(`Web Push: the browser could not subscribe: ${(error as Error).message}`, { cause: error })
+    }
+  }
+  await api.apiFetch(SUBSCRIPTIONS_PATH, { method: 'POST', body: subscriptionBody(subscription, env.userAgent) })
+  return 'subscribed'
+}
+
+// unsubscribePush turns off Web Push on this device: it removes the
+// browser's subscription on the server and in the browser. With no
+// subscription there is nothing to remove, and it answers 'not-subscribed'
+// without calling the server.
+export async function unsubscribePush(api: PushApi, env: PushEnvironment): Promise<UnsubscribePushResult> {
+  const { serviceWorker } = env
+  if (serviceWorker === undefined || !env.pushManager) return 'unsupported'
+  const found = await serviceWorker.getRegistration()
+  if (found === undefined) return 'not-subscribed'
+  const subscription = await found.pushManager.getSubscription()
+  if (subscription === null) return 'not-subscribed'
+  await removeSubscription(api, subscription)
+  return 'unsubscribed'
+}

web/src/push/usePush.ts

@@ -0,0 +1,29 @@
+import { useMemo } from 'react'
+import { useApi } from '../api/ApiContext.tsx'
+import {
+  browserPushEnvironment,
+  subscribePush,
+  unsubscribePush,
+  type SubscribePushResult,
+  type UnsubscribePushResult,
+} from './subscribe.ts'
+
+export type Push = {
+  // subscribePush turns on Web Push on this device; call it only from a tap.
+  subscribePush(): Promise<SubscribePushResult>
+  // unsubscribePush turns off Web Push on this device.
+  unsubscribePush(): Promise<UnsubscribePushResult>
+}
+
+// usePush binds subscribePush and unsubscribePush to the app's API client
+// and this browser.
+export function usePush(): Push {
+  const api = useApi()
+  return useMemo(
+    () => ({
+      subscribePush: () => subscribePush(api, browserPushEnvironment()),
+      unsubscribePush: () => unsubscribePush(api, browserPushEnvironment()),
+    }),
+    [api],
+  )
+}

web/src/sw.test.ts

@@ -50,3 +50,57 @@ describe('service worker activation', () => {
     expect(cacheStorage.delete).toHaveBeenCalledTimes(2)
   })
 })
+
+// The push listeners only hand src/push/notification.ts the worker's globals;
+// jsdom has no ServiceWorkerGlobalScope, so registration and clients are
+// stubbed and the events are plain Events with the worker event's fields.
+describe('service worker push listeners', () => {
+  afterEach(() => {
+    vi.unstubAllGlobals()
+  })
+
+  async function dispatch(type: string, fields: object): Promise<void> {
+    vi.stubGlobal('caches', { keys: vi.fn(async () => []), delete: vi.fn() })
+    vi.stubGlobal('__WB_MANIFEST', [])
+    await import('./sw')
+    const pending: Promise<unknown>[] = []
+    self.dispatchEvent(
+      Object.assign(new Event(type), { waitUntil: (promise: Promise<unknown>) => pending.push(promise) }, fields),
+    )
+    expect(pending).toHaveLength(1)
+    await Promise.all(pending)
+  }
+
+  it('shows a push message as a notification', async () => {
+    const registration = { showNotification: vi.fn(async () => {}) }
+    vi.stubGlobal('registration', registration)
+    const payload = JSON.stringify({ title: 'Plan ready', body: 'Adjust the Draft board.', tag: 'plan_ready', url: '/plan' })
+    await dispatch('push', { data: { text: () => payload } })
+    expect(registration.showNotification).toHaveBeenCalledWith('Plan ready', {
+      body: 'Adjust the Draft board.',
+      tag: 'plan_ready',
+      icon: '/icons/icon-192.png',
+      badge: '/icons/icon-192.png',
+      data: { url: '/plan' },
+    })
+  })
+
+  it('shows the generic notification for a push without a payload', async () => {
+    const registration = { showNotification: vi.fn(async () => {}) }
+    const warn = vi.spyOn(console, 'warn').mockImplementation(() => {})
+    vi.stubGlobal('registration', registration)
+    await dispatch('push', { data: null })
+    expect(registration.showNotification).toHaveBeenCalledWith('MealQuest', expect.objectContaining({ data: { url: '/' } }))
+    expect(warn).toHaveBeenCalledWith('MealQuest: push message has no payload; showing the generic notification')
+    warn.mockRestore()
+  })
+
+  it('closes a tapped notification and opens its url', async () => {
+    const clients = { matchAll: vi.fn(async () => []), openWindow: vi.fn(async () => null) }
+    vi.stubGlobal('clients', clients)
+    const notification = { data: { url: '/discover' }, close: vi.fn() }
+    await dispatch('notificationclick', { notification })
+    expect(notification.close).toHaveBeenCalled()
+    expect(clients.openWindow).toHaveBeenCalledWith(`${self.location.origin}/discover`)
+  })
+})

web/src/sw.ts

@@ -15,6 +15,7 @@ import { ExpirationPlugin } from 'workbox-expiration'
 import { PrecacheFallbackPlugin, matchPrecache, precacheAndRoute } from 'workbox-precaching'
 import { registerRoute } from 'workbox-routing'
 import { CacheFirst, NetworkOnly, type Strategy } from 'workbox-strategies'
+import { openNotification, showPush } from './push/notification'
 import { createApiStrategy } from './sw/apiStrategy'
 import {
   cacheNames,
@@ -113,3 +114,18 @@ self.addEventListener('activate', (event) => {
 self.addEventListener('message', (event) => {
   if (event.data?.type === 'SKIP_WAITING') void self.skipWaiting()
 })
+
+// Web Push: src/push/notification.ts decides what to show and where a tap
+// goes; these listeners only hand it the worker's globals. A payload that is
+// not a MealQuest notice still shows a generic notification, and the reason
+// is logged.
+self.addEventListener('push', (event) => {
+  event.waitUntil(
+    showPush(event.data?.text() ?? null, self.registration, self.location.origin, (message) => console.warn(message)),
+  )
+})
+
+self.addEventListener('notificationclick', (event) => {
+  event.notification.close()
+  event.waitUntil(openNotification(event.notification.data, self.clients, self.location.origin))
+})

web/src/sw/worker.test.ts

@@ -44,3 +44,13 @@ describe('service worker source', () => {
     )
   })
 })
+
+describe('service worker push listeners source', () => {
+  it('delegates push and notificationclick to src/push/notification.ts', () => {
+    expect(source).toContain("import { openNotification, showPush } from './push/notification'")
+    expect(source).toMatch(/self\.addEventListener\('push', \(event\) => \{\s*event\.waitUntil\(\s*showPush\(event\.data\?\.text\(\) \?\? null, self\.registration, self\.location\.origin,/)
+    expect(source).toMatch(
+      /self\.addEventListener\('notificationclick', \(event\) => \{\s*event\.notification\.close\(\)\s*event\.waitUntil\(openNotification\(event\.notification\.data, self\.clients, self\.location\.origin\)\)/,
+    )
+  })
+})