Add Google Calendar OAuth connect and disconnect

GET /api/v1/integrations/google/connect sends the browser to Google's
consent screen (calendar.events and calendar.calendarlist.readonly,
access_type=offline, prompt=consent, PKCE S256) with a state carried in a
signed __Host-mealquest_google flow cookie bound to the session.
GET /api/v1/integrations/google/callback checks the state and session,
exchanges the code, refuses a response without a refresh token
(reconnect_required) or without both scopes, seals the refresh token with
secretbox into integrations_google and sets connected_at.
DELETE /api/v1/integrations/google revokes the token at Google and clears
it; a revoke failure keeps the connection so it can be retried.

- internal/gcal: the connect service; Google endpoints are overridable and
  internal/gcal/gcaltest fakes the token and revoke endpoints.
- internal/auth: the login cookie becomes the exported FlowCookie both
  flows use (same wire format); CheckRedirect and ExchangeError are
  exported for reuse.
- internal/config: MEALQUEST_GOOGLE_CLIENT_ID and
  MEALQUEST_GOOGLE_CLIENT_SECRET_FILE, required at boot.
- DeleteIntegrationsGoogle query (sqlc regenerated); no migration, the
  integrations_google table already exists.
- deploy: compose mounts google_client_secret; .env.example and RUNBOOK
  document the Google OAuth client, its redirect URI and rotation.

Maestro task 1e9d7850-3a09-4572-b8a1-cb18cd4774cb.

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

cmd/server/boot_test.go

@@ -44,6 +44,10 @@ func loadConfig(t *testing.T, keyFile string) config.Config {
 	if err := os.WriteFile(clientSecretPath, []byte("client-secret\n"), 0o600); err != nil {
 		t.Fatal(err)
 	}
+	googleSecretPath := filepath.Join(dir, "google_client_secret")
+	if err := os.WriteFile(googleSecretPath, []byte("google-secret\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
 	t.Setenv(config.EnvHTTPAddr, "127.0.0.1:0")
 	t.Setenv(config.EnvPublicURL, "http://localhost")
 	t.Setenv(config.EnvDataDir, t.TempDir())
@@ -53,6 +57,8 @@ func loadConfig(t *testing.T, keyFile string) config.Config {
 	t.Setenv(config.EnvOIDCClientID, "mealquest")
 	t.Setenv(config.EnvOIDCClientSecretFile, clientSecretPath)
 	t.Setenv(config.EnvOIDCAllowedGroups, "mealquest-admin")
+	t.Setenv(config.EnvGoogleClientID, "mealquest.apps.googleusercontent.com")
+	t.Setenv(config.EnvGoogleClientSecretFile, googleSecretPath)
 	// 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

@@ -21,6 +21,7 @@ import (
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/dinners"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/forwarded"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/frontend"
+	"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/plan"
@@ -118,6 +119,18 @@ func run(cfg config.Config, logger *slog.Logger) error {
 		return err
 	}
 
+	googleSvc, err := gcal.NewService(db, box, gcal.Config{
+		ClientID:     cfg.GoogleClientID,
+		ClientSecret: cfg.GoogleClientSecret.Reveal(),
+		PublicURL:    cfg.PublicURL,
+		SecretKey:    []byte(cfg.SecretKey.Reveal()),
+		Endpoint:     gcal.GoogleEndpoint,
+		RevokeURL:    gcal.GoogleRevokeURL,
+	})
+	if err != nil {
+		return err
+	}
+
 	sessions, err := auth.NewSessionManager(db, cfg.SessionIdle, cfg.SessionMax)
 	if err != nil {
 		return err
@@ -134,7 +147,7 @@ func run(cfg config.Config, logger *slog.Logger) error {
 		return err
 	}
 
-	router, err := server.NewRouter(logger, version, cfg.TrustedProxy, authFlow, sessions, settings, search, ai, dinnerSvc, suggestSvc, planSvc, runner, photos, frontend.Assets())
+	router, err := server.NewRouter(logger, version, cfg.TrustedProxy, authFlow, sessions, settings, search, ai, dinnerSvc, suggestSvc, planSvc, googleSvc, runner, photos, frontend.Assets())
 	if err != nil {
 		return err
 	}

deploy/.env.example

@@ -8,6 +8,7 @@
 #   mkdir -p deploy/secrets && chmod 700 deploy/secrets
 #   head -c 32 /dev/urandom | base64 > deploy/secrets/secret_key
 #   printf '%s\n' '<Authentik client secret>' > deploy/secrets/oidc_client_secret
+#   printf '%s\n' '<Google OAuth client secret>' > deploy/secrets/google_client_secret
 #   sudo chown 10001:10001 deploy/secrets/* && sudo chmod 600 deploy/secrets/*
 #
 # SearXNG's secret key is the exception: compose reads it itself, so it
@@ -54,6 +55,14 @@ MEALQUEST_OIDC_CLIENT_ID=mealquest
 # Comma-separated Authentik groups whose members may sign in.
 MEALQUEST_OIDC_ALLOWED_GROUPS=mealquest-admin
 
+# --- Google Calendar (Push to Calendar) ------------------------------------
+
+# Client ID of the Google OAuth web client (deploy/RUNBOOK.md "Google
+# Calendar OAuth client"). Required: the service will not start without it
+# and the client secret file. Its authorized redirect URI is
+# <MEALQUEST_PUBLIC_URL origin>/api/v1/integrations/google/callback.
+MEALQUEST_GOOGLE_CLIENT_ID=<client id>.apps.googleusercontent.com
+
 # 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
@@ -67,6 +76,8 @@ MEALQUEST_SESSION_MAX=4320h
 #   Base64 of 32 random bytes; encrypts secrets at rest (AES-256-GCM).
 # MEALQUEST_OIDC_CLIENT_SECRET_FILE=/run/secrets/oidc_client_secret
 #   The Authentik provider's client secret.
+# MEALQUEST_GOOGLE_CLIENT_SECRET_FILE=/run/secrets/google_client_secret
+#   The Google OAuth web client's secret.
 # 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
@@ -81,7 +92,3 @@ MEALQUEST_SESSION_MAX=4320h
 # MEALQUEST_VAPID_PUBLIC_KEY=<base64url VAPID public key>
 # MEALQUEST_VAPID_PRIVATE_KEY_FILE=/run/secrets/vapid_private_key
 # MEALQUEST_VAPID_SUBJECT=mailto:<owner address>
-#
-# Google Calendar OAuth web client (Feature 16).
-# MEALQUEST_GOOGLE_CLIENT_ID=<client id>.apps.googleusercontent.com
-# MEALQUEST_GOOGLE_CLIENT_SECRET_FILE=/run/secrets/google_client_secret

deploy/RUNBOOK.md

@@ -33,6 +33,8 @@ On office-srvr (10.60.1.14), as recorded on 2026-10-05:
 Elsewhere:
 
 - Admin access to Authentik at <https://auth.cubecraftlabs.com>.
+- Owner access to the Google Cloud project that holds MealQuest's OAuth
+  client (see "Google Calendar OAuth client").
 - SSH access to the Traefik host 10.60.1.33.
 - Cloudflare access for the `cubecraftlabs.com` zone, and admin access to
   both Pi-holes (10.60.1.101 `dns.ccl`, 10.60.1.85 `dns2.ccl`).
@@ -129,6 +131,7 @@ Values in use:
 | `MEALQUEST_OIDC_ISSUER` | `https://auth.cubecraftlabs.com/application/o/mealquest/` |
 | `MEALQUEST_OIDC_CLIENT_ID` | `i6zraqmWsF552b8nmte070LXz0SI5pRdArBxFxeq` (not a secret) |
 | `MEALQUEST_OIDC_ALLOWED_GROUPS` | `mealquest-admin` |
+| `MEALQUEST_GOOGLE_CLIENT_ID` | Client ID of the Google OAuth web client (not a secret; see "Google Calendar OAuth client") |
 | `MEALQUEST_SESSION_IDLE` / `MEALQUEST_SESSION_MAX` | `720h` / `4320h` |
 
 `MEALQUEST_HTTP_ADDR`, `MEALQUEST_DATA_DIR` and the `*_FILE` variables are
@@ -146,6 +149,7 @@ service refuses to start.
 | --- | --- | --- |
 | `secret_key` | base64 of 32 random bytes; encrypts stored secrets (AES-256-GCM) | `/run/secrets/secret_key` |
 | `oidc_client_secret` | Client Secret of the Authentik provider `mealquest` | `/run/secrets/oidc_client_secret` |
+| `google_client_secret` | Client secret of the Google OAuth web client | `/run/secrets/google_client_secret` |
 | `litestream_key` | dedicated SSH private key for the NAS (see "Backups") | `/etc/litestream/sftp_key` |
 | `searxng.env` | `SEARXNG_SECRET=<64 hex characters>`; SearXNG's secret key | not mounted; compose passes it as an environment variable |
 
@@ -156,11 +160,12 @@ it (as `env_file`), so it is owned by `overseer`, mode 0600.
 mkdir -p deploy/secrets && chmod 700 deploy/secrets
 head -c 32 /dev/urandom | base64 > deploy/secrets/secret_key
 printf '%s\n' '<Authentik client secret>' > deploy/secrets/oidc_client_secret
+printf '%s\n' '<Google OAuth client secret>' > deploy/secrets/google_client_secret
 # litestream_key: see "Backups" > "Database — Litestream"
-sudo chown 10001:10001 deploy/secrets/secret_key deploy/secrets/oidc_client_secret deploy/secrets/litestream_key
+sudo chown 10001:10001 deploy/secrets/secret_key deploy/secrets/oidc_client_secret deploy/secrets/google_client_secret deploy/secrets/litestream_key
 sudo chmod 600 deploy/secrets/*
 (umask 077; printf 'SEARXNG_SECRET=%s\n' "$(openssl rand -hex 32)" > deploy/secrets/searxng.env)
-sudo ls -la deploy/secrets   # three files mealquest mealquest, searxng.env overseer overseer; all -rw-------
+sudo ls -la deploy/secrets   # four files mealquest mealquest, searxng.env overseer overseer; all -rw-------
 ```
 
 The `mealquest` host user (uid/gid 10001) is created in "Media — nightly
@@ -238,6 +243,38 @@ On 2026-10-05 discovery returned 200 with issuer
 `https://auth.cubecraftlabs.com/application/o/mealquest/` and
 `id_token_signing_alg_values_supported: ["RS256"]`.
 
+## Google Calendar OAuth client
+
+Push to Calendar connects the household's Google account with a Google
+OAuth web client. MealQuest calls Google's OAuth and Calendar REST
+endpoints directly. **The service will not start without
+`MEALQUEST_GOOGLE_CLIENT_ID` and `deploy/secrets/google_client_secret`**,
+so create the client before deploying a release that contains Feature 16.
+
+In the Google Cloud console, in the project that holds MealQuest:
+
+| Object | Setting |
+| --- | --- |
+| API | Google Calendar API enabled |
+| OAuth consent screen | User type External; app name MealQuest; publishing status **In production** (a client left in Testing gets refresh tokens that expire after 7 days, so Push to Calendar would stop working a week after connecting) |
+| Scopes | `https://www.googleapis.com/auth/calendar.events` and `https://www.googleapis.com/auth/calendar.calendarlist.readonly` |
+| Credentials | OAuth client ID, application type **Web application**, name `mealquest` |
+| Authorized redirect URI | `https://mealquest.cubecraftlabs.com/api/v1/integrations/google/callback` (exactly; it is `MEALQUEST_PUBLIC_URL`'s origin plus that path) |
+| Client ID | in `deploy/.env` as `MEALQUEST_GOOGLE_CLIENT_ID` (not a secret) |
+| Client secret | in `deploy/secrets/google_client_secret` only |
+
+The app is unverified, so Google shows an "unverified app" warning on the
+consent screen; choose to continue. That is expected for a single-household
+deployment.
+
+To connect, a signed-in household member opens
+`https://mealquest.cubecraftlabs.com/api/v1/integrations/google/connect`
+(the Settings screen links there once it ships). MealQuest asks for offline
+access with consent always prompted, and lands back on
+`/settings/calendar` once the refresh token is stored. Disconnecting
+(`DELETE /api/v1/integrations/google`) revokes the token at Google and
+forgets it.
+
 ## Reverse proxy (Traefik)
 
 MealQuest is published at <https://mealquest.cubecraftlabs.com> by the
@@ -1313,6 +1350,23 @@ Sign in at <https://mealquest.cubecraftlabs.com> to confirm; sign-ins
 fail between regenerating the secret in Authentik and recreating the
 service.
 
+### Google OAuth client secret (`deploy/secrets/google_client_secret`)
+
+In the Google Cloud console, open the OAuth client `mealquest`, add a new
+client secret, write it to the file (same owner and mode as above) and
+recreate the service:
+
+```sh
+printf '%s\n' '<new Google OAuth client secret>' | sudo tee deploy/secrets/google_client_secret >/dev/null
+sudo chown 10001:10001 deploy/secrets/google_client_secret
+sudo chmod 600 deploy/secrets/google_client_secret
+docker compose -f deploy/compose.yaml up -d --force-recreate mealquest
+```
+
+Then disable and delete the old secret in the console. A new client secret
+leaves the household's stored refresh token valid, so nothing needs
+reconnecting.
+
 ### LLM API key
 
 Stored encrypted in the database, not in `deploy/`. In the app, open

deploy/compose.yaml

@@ -32,10 +32,12 @@ services:
       MEALQUEST_DATA_DIR: /data
       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_SEARXNG_URL: http://searxng:8080
     secrets:
       - secret_key
       - oidc_client_secret
+      - google_client_secret
     volumes:
       - mealquest-data:/data
     ports:
@@ -128,6 +130,8 @@ secrets:
     file: ./secrets/secret_key
   oidc_client_secret:
     file: ./secrets/oidc_client_secret
+  google_client_secret:
+    file: ./secrets/google_client_secret
 
 volumes:
   mealquest-data:

docs/ARCHITECTURE.md

@@ -618,6 +618,28 @@ Runs are recorded in `schedule_runs` and executed through `jobs`.
   not come back.
 - Connected once with Google OAuth in Settings; one event per planned
   dinner.
+- `internal/gcal` owns the connection, as a confidential OAuth web client
+  (`MEALQUEST_GOOGLE_CLIENT_ID`, `MEALQUEST_GOOGLE_CLIENT_SECRET_FILE`, both
+  required at boot) over plain REST — no Google SDK. All three routes are
+  under the signed-in `/api/v1`:
+  - `GET /api/v1/integrations/google/connect` redirects to Google's consent
+    screen with scopes `calendar.events` and `calendar.calendarlist.readonly`,
+    `access_type=offline`, `prompt=consent` and PKCE. Its `state` travels in
+    the signed `__Host-mealquest_google` flow cookie (the same
+    `auth.FlowCookie` mechanism as the login cookie), bound to the session by
+    a hash of the session's CSRF token.
+  - `GET /api/v1/integrations/google/callback` (the redirect URI:
+    `MEALQUEST_PUBLIC_URL`'s origin plus this path) checks the state and
+    session, exchanges the code, refuses a response with no refresh token
+    (`reconnect_required`) or without both scopes, seals the refresh token
+    with `secretbox` into `integrations_google.refresh_token_ct`, sets
+    `connected_at` and redirects to `/settings/calendar`. A reconnect keeps
+    the chosen calendar and clears `last_sync_error`.
+  - `DELETE /api/v1/integrations/google` (CSRF-checked) revokes the token at
+    Google, then deletes the row; a token Google reports as `invalid_token`
+    counts as revoked, and any other revoke failure keeps the connection.
+  - No response, log line or error ever holds a token or Google's response
+    text.
 - **Deterministic event ids**; each plan day records its
   `calendar_event_id`.
 

internal/auth/auth.go

@@ -107,7 +107,7 @@ func New(ctx context.Context, cfg Config, sessions Sessions, logger *slog.Logger
 		return nil, err
 	}
 
-	client := &http.Client{Timeout: providerTimeout, CheckRedirect: checkRedirect}
+	client := &http.Client{Timeout: providerTimeout, CheckRedirect: CheckRedirect}
 	discovery := *client
 	recorder := &statusRecorder{next: http.DefaultTransport}
 	discovery.Transport = recorder
@@ -205,11 +205,12 @@ func checkEndpoint(name, raw string) error {
 // maxRedirects matches net/http's default redirect limit.
 const maxRedirects = 10
 
-// checkRedirect is the provider client's redirect policy. On a 307 or 308 to
-// the same host Go resends the body and Authorization header, which carry the
-// code and client secret, so every target must pass secureurl.Check and an
-// https:// request never follows a redirect to plain http://, even loopback.
-func checkRedirect(req *http.Request, via []*http.Request) error {
+// CheckRedirect is the redirect policy of every client that talks to an
+// OAuth provider. On a 307 or 308 to the same host Go resends the body and
+// Authorization header, which carry the code and client secret, so every
+// target must pass secureurl.Check and an https:// request never follows a
+// redirect to plain http://, even loopback.
+func CheckRedirect(req *http.Request, via []*http.Request) error {
 	if len(via) >= maxRedirects {
 		return fmt.Errorf("stopped after %d redirects", maxRedirects)
 	}
@@ -350,7 +351,7 @@ func (a *Auth) verify(ctx context.Context, code string, state loginState) (Claim
 	token, err := a.oauth.Exchange(context.WithValue(ctx, oauth2.HTTPClient, a.client), code,
 		oauth2.VerifierOption(state.Verifier))
 	if err != nil {
-		return Claims{}, exchangeError(err)
+		return Claims{}, ExchangeError(err)
 	}
 	raw, ok := token.Extra("id_token").(string)
 	if !ok || raw == "" {
@@ -400,7 +401,7 @@ func (a *Auth) userinfoGroups(ctx context.Context, token *oauth2.Token, subject
 }
 
 // userinfoError reduces a failed userinfo request to a fixed category, like
-// exchangeError: go-oidc's error text can carry the response body.
+// ExchangeError: go-oidc's error text can carry the response body.
 func userinfoError(err error) error {
 	var transport *url.Error
 	if errors.As(err, &transport) {
@@ -425,10 +426,11 @@ func (a *Auth) member(groups []string) bool {
 	return slices.ContainsFunc(groups, func(g string) bool { return slices.Contains(a.allowed, g) })
 }
 
-// exchangeError reduces a failed code exchange to a fixed category and safe
-// metadata. The oauth2 error text can carry the token endpoint's response
-// body or error_description, which may echo credentials, so it is dropped.
-func exchangeError(err error) error {
+// ExchangeError reduces a failed OAuth code exchange to a fixed category and
+// safe metadata. The oauth2 error text can carry the token endpoint's
+// response body or error_description, which may echo credentials, so it is
+// dropped.
+func ExchangeError(err error) error {
 	var retrieve *oauth2.RetrieveError
 	var transport *url.Error
 	switch {

internal/auth/auth_test.go

@@ -1060,7 +1060,7 @@ func TestCheckRedirect(t *testing.T) {
 		{"https://auth.example.com/token", "ftp://auth.example.com/token", false},
 	}
 	for _, tc := range tests {
-		err := checkRedirect(request(tc.to), []*http.Request{request(tc.from)})
+		err := CheckRedirect(request(tc.to), []*http.Request{request(tc.from)})
 		if (err == nil) != tc.ok {
 			t.Errorf("redirect %s -> %s: error = %v, want ok=%v", tc.from, tc.to, err, tc.ok)
 		}
@@ -1069,7 +1069,7 @@ func TestCheckRedirect(t *testing.T) {
 	for i := range via {
 		via[i] = request("https://auth.example.com/token")
 	}
-	if err := checkRedirect(request("https://auth.example.com/token"), via); err == nil {
+	if err := CheckRedirect(request("https://auth.example.com/token"), via); err == nil {
 		t.Errorf("redirect after %d hops: error = nil, want limit", maxRedirects)
 	}
 }

internal/auth/cookie.go

@@ -27,38 +27,86 @@ type loginState struct {
 	Nonce    string `json:"n"`
 	Verifier string `json:"v"`
 	Return   string `json:"r"`
-	Expires  int64  `json:"e"` // Unix seconds
+	FlowExpiry
 }
 
-// loginCookie signs and verifies the login cookie with HMAC-SHA256.
+// loginCookie is the FlowCookie carrying loginState.
 type loginCookie struct {
-	key []byte
+	flow FlowCookie
 }
 
 func newLoginCookie(secretKey []byte) loginCookie {
-	mac := hmac.New(sha256.New, secretKey)
-	mac.Write([]byte(loginCookieKeyLabel))
-	return loginCookie{key: mac.Sum(nil)}
+	return loginCookie{flow: NewFlowCookie(loginCookieName, loginCookieKeyLabel, loginCookieTTL, secretKey)}
 }
 
-func (c loginCookie) sign(payload string) string {
+func (c loginCookie) set(w http.ResponseWriter, s loginState, now time.Time) error {
+	return c.flow.Set(w, &s, now)
+}
+
+func (c loginCookie) clear(w http.ResponseWriter) { c.flow.Clear(w) }
+
+func (c loginCookie) read(r *http.Request, now time.Time) (loginState, error) {
+	var s loginState
+	if err := c.flow.Read(r, &s, now); err != nil {
+		return loginState{}, err
+	}
+	return s, nil
+}
+
+// FlowExpiry is embedded in every value a FlowCookie carries; Set fills it
+// and Read enforces it.
+type FlowExpiry struct {
+	Expires int64 `json:"e"` // Unix seconds
+}
+
+func (e *FlowExpiry) flowExpiry() *FlowExpiry { return e }
+
+// flowValue is a pointer to a struct that embeds FlowExpiry.
+type flowValue interface {
+	flowExpiry() *FlowExpiry
+}
+
+// FlowCookie carries a redirect flow's state — the OAuth state, PKCE
+// verifier and the like — from the request that sends the browser to a
+// provider to the callback it returns to. The value is JSON, signed with
+// HMAC-SHA256 under a key derived from the server secret and the cookie's
+// own label, and expires after a fixed time. It is not encrypted: it must
+// not hold anything the browser may not see.
+type FlowCookie struct {
+	name string
+	ttl  time.Duration
+	key  []byte
+}
+
+// NewFlowCookie returns the flow cookie name, valid for ttl, signed under a
+// key derived from secretKey and keyLabel. Each flow uses its own keyLabel so
+// one flow's cookie never verifies as another's. name must carry the __Host-
+// prefix: the cookie is Secure, host-only and Path=/.
+func NewFlowCookie(name, keyLabel string, ttl time.Duration, secretKey []byte) FlowCookie {
+	mac := hmac.New(sha256.New, secretKey)
+	mac.Write([]byte(keyLabel))
+	return FlowCookie{name: name, ttl: ttl, key: mac.Sum(nil)}
+}
+
+func (c FlowCookie) sign(payload string) string {
 	mac := hmac.New(sha256.New, c.key)
 	mac.Write([]byte(payload))
 	return base64.RawURLEncoding.EncodeToString(mac.Sum(nil))
 }
 
-func (c loginCookie) set(w http.ResponseWriter, s loginState, now time.Time) error {
-	s.Expires = now.Add(loginCookieTTL).Unix()
-	data, err := json.Marshal(s)
+// Set stores v, which expires ttl after now, in the cookie.
+func (c FlowCookie) Set(w http.ResponseWriter, v flowValue, now time.Time) error {
+	v.flowExpiry().Expires = now.Add(c.ttl).Unix()
+	data, err := json.Marshal(v)
 	if err != nil {
 		return err
 	}
 	payload := base64.RawURLEncoding.EncodeToString(data)
 	http.SetCookie(w, &http.Cookie{
-		Name:     loginCookieName,
+		Name:     c.name,
 		Value:    payload + "." + c.sign(payload),
 		Path:     "/",
-		MaxAge:   int(loginCookieTTL / time.Second),
+		MaxAge:   int(c.ttl / time.Second),
 		Secure:   true,
 		HttpOnly: true,
 		// Lax so the cookie rides the provider's top-level redirect back.
@@ -67,9 +115,11 @@ func (c loginCookie) set(w http.ResponseWriter, s loginState, now time.Time) err
 	return nil
 }
 
-func (c loginCookie) clear(w http.ResponseWriter) {
+// Clear removes the cookie. A callback clears it before reading, so it is
+// single-use.
+func (c FlowCookie) Clear(w http.ResponseWriter) {
 	http.SetCookie(w, &http.Cookie{
-		Name:     loginCookieName,
+		Name:     c.name,
 		Path:     "/",
 		MaxAge:   -1,
 		Secure:   true,
@@ -78,27 +128,28 @@ func (c loginCookie) clear(w http.ResponseWriter) {
 	})
 }
 
-func (c loginCookie) read(r *http.Request, now time.Time) (loginState, error) {
-	cookie, err := r.Cookie(loginCookieName)
+// Read verifies the cookie r carries and decodes it into v. It fails when
+// the cookie is missing, its signature is invalid or it has expired at now.
+func (c FlowCookie) Read(r *http.Request, v flowValue, now time.Time) error {
+	cookie, err := r.Cookie(c.name)
 	if err != nil {
-		return loginState{}, errors.New("login cookie missing")
+		return fmt.Errorf("%s cookie missing", c.name)
 	}
 	payload, sig, ok := strings.Cut(cookie.Value, ".")
 	if !ok || !hmac.Equal([]byte(sig), []byte(c.sign(payload))) {
-		return loginState{}, errors.New("login cookie signature invalid")
+		return fmt.Errorf("%s cookie signature invalid", c.name)
 	}
 	data, err := base64.RawURLEncoding.DecodeString(payload)
 	if err != nil {
-		return loginState{}, fmt.Errorf("login cookie encoding: %w", err)
+		return fmt.Errorf("%s cookie encoding: %w", c.name, err)
 	}
-	var s loginState
-	if err := json.Unmarshal(data, &s); err != nil {
-		return loginState{}, fmt.Errorf("login cookie payload: %w", err)
+	if err := json.Unmarshal(data, v); err != nil {
+		return fmt.Errorf("%s cookie payload: %w", c.name, err)
 	}
-	if now.Unix() >= s.Expires {
-		return loginState{}, errors.New("login cookie expired")
+	if now.Unix() >= v.flowExpiry().Expires {
+		return fmt.Errorf("%s cookie expired", c.name)
 	}
-	return s, nil
+	return nil
 }
 
 // returnPath validates the optional post-login return path. Empty means "/".

internal/config/config.go

@@ -29,6 +29,9 @@ const (
 	EnvOIDCClientSecretFile = "MEALQUEST_OIDC_CLIENT_SECRET_FILE"
 	EnvOIDCAllowedGroups    = "MEALQUEST_OIDC_ALLOWED_GROUPS"
 
+	EnvGoogleClientID         = "MEALQUEST_GOOGLE_CLIENT_ID"
+	EnvGoogleClientSecretFile = "MEALQUEST_GOOGLE_CLIENT_SECRET_FILE"
+
 	EnvSessionIdle = "MEALQUEST_SESSION_IDLE"
 	EnvSessionMax  = "MEALQUEST_SESSION_MAX"
 
@@ -61,6 +64,12 @@ type Config struct {
 	// OIDCAllowedGroups lists the groups whose members may sign in.
 	OIDCAllowedGroups []string
 
+	// GoogleClientID and GoogleClientSecret are the Google OAuth web client
+	// Push to Calendar connects with. Its redirect URI is PublicURL's origin
+	// followed by /api/v1/integrations/google/callback.
+	GoogleClientID     string
+	GoogleClientSecret Secret
+
 	// SessionIdle ends a session left unused this long.
 	SessionIdle time.Duration
 	// SessionMax ends every session this long after sign-in, used or not.
@@ -110,6 +119,9 @@ func load(lookup func(string) (string, bool)) (Config, error) {
 		OIDCClientSecret:  r.secretFile(EnvOIDCClientSecretFile),
 		OIDCAllowedGroups: r.list(EnvOIDCAllowedGroups),
 
+		GoogleClientID:     r.str(EnvGoogleClientID),
+		GoogleClientSecret: r.secretFile(EnvGoogleClientSecretFile),
+
 		SessionIdle: r.sessionDuration(EnvSessionIdle, DefaultSessionIdle),
 		SessionMax:  r.sessionDuration(EnvSessionMax, DefaultSessionMax),
 

internal/config/config_test.go

@@ -29,6 +29,10 @@ func TestLoad(t *testing.T) {
 	if err := os.WriteFile(clientSecretPath, []byte("client-s3cret\n"), 0o600); err != nil {
 		t.Fatal(err)
 	}
+	googleSecretPath := filepath.Join(dir, "google_client_secret")
+	if err := os.WriteFile(googleSecretPath, []byte("google-s3cret\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
 	emptyPath := filepath.Join(dir, "empty_secret")
 	if err := os.WriteFile(emptyPath, []byte("\n"), 0o600); err != nil {
 		t.Fatal(err)
@@ -46,6 +50,9 @@ func TestLoad(t *testing.T) {
 			EnvOIDCClientID:         "mealquest",
 			EnvOIDCClientSecretFile: clientSecretPath,
 			EnvOIDCAllowedGroups:    "mealquest-admin",
+
+			EnvGoogleClientID:         "mealquest.apps.googleusercontent.com",
+			EnvGoogleClientSecretFile: googleSecretPath,
 		}
 	}
 	with := func(changes map[string]string, unset ...string) map[string]string {
@@ -94,6 +101,7 @@ func TestLoad(t *testing.T) {
 			badVars: []string{
 				EnvHTTPAddr, EnvPublicURL, EnvDataDir, EnvShutdownTimeout, EnvSecretKeyFile,
 				EnvOIDCIssuer, EnvOIDCClientID, EnvOIDCClientSecretFile, EnvOIDCAllowedGroups,
+				EnvGoogleClientID, EnvGoogleClientSecretFile,
 			},
 		},
 		{
@@ -211,6 +219,31 @@ func TestLoad(t *testing.T) {
 			env:     with(map[string]string{"MEALQUEST_SECRET_KEY": "inline"}),
 			badVars: []string{"MEALQUEST_SECRET_KEY"},
 		},
+		{
+			name:    "Google client ID missing",
+			env:     with(nil, EnvGoogleClientID),
+			badVars: []string{EnvGoogleClientID},
+		},
+		{
+			name:    "Google client secret file missing",
+			env:     with(nil, EnvGoogleClientSecretFile),
+			badVars: []string{EnvGoogleClientSecretFile},
+		},
+		{
+			name:    "Google client secret file unreadable",
+			env:     with(map[string]string{EnvGoogleClientSecretFile: unreadablePath}),
+			badVars: []string{EnvGoogleClientSecretFile},
+		},
+		{
+			name:    "Google client secret file empty",
+			env:     with(map[string]string{EnvGoogleClientSecretFile: emptyPath}),
+			badVars: []string{EnvGoogleClientSecretFile},
+		},
+		{
+			name:    "inline Google client secret rejected",
+			env:     with(map[string]string{"MEALQUEST_GOOGLE_CLIENT_SECRET": "inline"}),
+			badVars: []string{"MEALQUEST_GOOGLE_CLIENT_SECRET"},
+		},
 		{
 			name:    "inline OIDC client secret rejected",
 			env:     with(map[string]string{"MEALQUEST_OIDC_CLIENT_SECRET": "inline"}),
@@ -409,6 +442,10 @@ func TestLoadValues(t *testing.T) {
 	if err := os.WriteFile(clientSecretPath, []byte("client-s3cret\n"), 0o600); err != nil {
 		t.Fatal(err)
 	}
+	googleSecretPath := filepath.Join(dir, "google_client_secret")
+	if err := os.WriteFile(googleSecretPath, []byte("google-s3cret\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
 	env := map[string]string{
 		EnvHTTPAddr:        "127.0.0.1:9000",
 		EnvPublicURL:       "http://localhost:9000",
@@ -421,6 +458,9 @@ func TestLoadValues(t *testing.T) {
 		EnvOIDCClientSecretFile: clientSecretPath,
 		EnvOIDCAllowedGroups:    " mealquest-admin ,family",
 
+		EnvGoogleClientID:         "mealquest.apps.googleusercontent.com",
+		EnvGoogleClientSecretFile: googleSecretPath,
+
 		EnvDefaultTZ: "Europe/London",
 
 		EnvSearXNGURL: "http://searxng:8080",
@@ -454,6 +494,12 @@ func TestLoadValues(t *testing.T) {
 	if cfg.OIDCClientSecret.Reveal() != "client-s3cret" {
 		t.Errorf("OIDCClientSecret.Reveal() = %q", cfg.OIDCClientSecret.Reveal())
 	}
+	if cfg.GoogleClientID != "mealquest.apps.googleusercontent.com" {
+		t.Errorf("GoogleClientID = %q", cfg.GoogleClientID)
+	}
+	if cfg.GoogleClientSecret.Reveal() != "google-s3cret" {
+		t.Errorf("GoogleClientSecret.Reveal() = %q", cfg.GoogleClientSecret.Reveal())
+	}
 	if want := []string{"mealquest-admin", "family"}; !slices.Equal(cfg.OIDCAllowedGroups, want) {
 		t.Errorf("OIDCAllowedGroups = %q, want %q", cfg.OIDCAllowedGroups, want)
 	}
@@ -492,7 +538,7 @@ func TestSecretRedacted(t *testing.T) {
 
 	s := Secret{value: "s3cret-value"}
 	for _, format := range []string{"%v", "%s", "%+v", "%#v"} {
-		cfg := Config{SecretKey: s, OIDCClientSecret: s}
+		cfg := Config{SecretKey: s, OIDCClientSecret: s, GoogleClientSecret: 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)

internal/db/querier.go

@@ -50,6 +50,10 @@ type Querier interface {
 	// decided is left as it is (0 rows).
 	DecideSuggestion(ctx context.Context, arg DecideSuggestionParams) (int64, error)
 	DeleteAIRunsBefore(ctx context.Context, cutoff string) (int64, error)
+	// Deletes the row only while it still holds refresh_token_ct, so a
+	// connection made after the caller read the row is kept. Returns the number
+	// of rows deleted.
+	DeleteIntegrationsGoogle(ctx context.Context, refreshTokenCt []byte) (int64, error)
 	DeleteRecipeIngredients(ctx context.Context, recipeID string) error
 	DeleteRecipeSteps(ctx context.Context, recipeID string) error
 	FailJob(ctx context.Context, arg FailJobParams) (int64, error)

internal/db/settings.sql.go

@@ -10,6 +10,22 @@ import (
 	"database/sql"
 )
 
+const deleteIntegrationsGoogle = `-- name: DeleteIntegrationsGoogle :execrows
+DELETE FROM integrations_google
+WHERE id = 1 AND refresh_token_ct = ?
+`
+
+// Deletes the row only while it still holds refresh_token_ct, so a
+// connection made after the caller read the row is kept. Returns the number
+// of rows deleted.
+func (q *Queries) DeleteIntegrationsGoogle(ctx context.Context, refreshTokenCt []byte) (int64, error) {
+	result, err := q.db.ExecContext(ctx, deleteIntegrationsGoogle, refreshTokenCt)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected()
+}
+
 const getAISettings = `-- name: GetAISettings :one
 SELECT id, provider, base_url, model, temperature, system_prompt, api_key_ct, api_key_last4, key_verified_at, created_at, updated_at FROM ai_settings
 WHERE id = 1

internal/gcal/connect.go

@@ -0,0 +1,357 @@
+// Package gcal connects the household's Google account for Push to Calendar.
+// The service is a confidential OAuth web client: the authorization code,
+// tokens and client secret stay on the server. The refresh token is stored
+// sealed by secretbox in integrations_google and is never logged or
+// returned.
+package gcal
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/sha256"
+	"crypto/subtle"
+	"database/sql"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"slices"
+	"strings"
+	"time"
+
+	"golang.org/x/oauth2"
+	"golang.org/x/oauth2/endpoints"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/auth"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/db"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/secretbox"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
+)
+
+// CallbackPath is where Google returns the browser after consent. It is
+// served under the signed-in /api/v1 router, so the redirect URI registered
+// with Google is MEALQUEST_PUBLIC_URL's origin followed by this path.
+const CallbackPath = "/api/v1/integrations/google/callback"
+
+// Scopes requested at connect: create and change the events MealQuest pushes,
+// and list the calendars the household can push to.
+var Scopes = []string{
+	"https://www.googleapis.com/auth/calendar.events",
+	"https://www.googleapis.com/auth/calendar.calendarlist.readonly",
+}
+
+// GoogleRevokeURL is Google's OAuth token revocation endpoint.
+const GoogleRevokeURL = "https://oauth2.googleapis.com/revoke"
+
+// GoogleEndpoint is Google's OAuth authorization and token endpoint.
+var GoogleEndpoint = oauth2.Endpoint{
+	AuthURL:   endpoints.Google.AuthURL,
+	TokenURL:  endpoints.Google.TokenURL,
+	AuthStyle: oauth2.AuthStyleInParams,
+}
+
+const (
+	connectCookieName = "__Host-mealquest_google"
+	connectCookieTTL  = 10 * time.Minute
+	// connectCookieKeyLabel separates the connect cookie's signing key from
+	// the login cookie's and every other key derived from the server secret.
+	connectCookieKeyLabel = "mealquest google connect cookie v1"
+	// googleTimeout bounds every request to Google.
+	googleTimeout = 10 * time.Second
+	// maxRevokeBody caps how much of a revoke response is read.
+	maxRevokeBody = 4 << 10
+)
+
+var (
+	// ErrBadState means the callback's state is missing, does not match the
+	// connect cookie, or the cookie is missing, expired or belongs to another
+	// session.
+	ErrBadState = errors.New("gcal: connect state is missing, expired or does not match this session")
+	// ErrDenied means Google returned an authorization error, usually because
+	// the household declined consent.
+	ErrDenied = errors.New("gcal: Google did not grant access")
+	// ErrNoCode means the callback carries no authorization code.
+	ErrNoCode = errors.New("gcal: callback has no authorization code")
+	// ErrNoRefreshToken means Google granted access without a refresh token,
+	// so MealQuest could not push later; the household must connect again.
+	ErrNoRefreshToken = errors.New("gcal: Google returned no refresh token")
+	// ErrScopes means the household did not grant every scope in Scopes.
+	ErrScopes = errors.New("gcal: Google did not grant every Calendar permission")
+	// ErrNotConnected means no Google account is connected.
+	ErrNotConnected = errors.New("gcal: Google Calendar is not connected")
+	// ErrChanged means the connection changed while it was being
+	// disconnected.
+	ErrChanged = errors.New("gcal: Google Calendar connection changed during disconnect")
+)
+
+// Config is what NewService needs to talk to Google.
+type Config struct {
+	ClientID     string
+	ClientSecret string
+	// PublicURL is the service's public URL; its origin prefixes CallbackPath
+	// to form the redirect URI.
+	PublicURL *url.URL
+	// SecretKey is the server key the connect cookie's signing key derives
+	// from.
+	SecretKey []byte
+	// Endpoint is Google's authorization and token endpoint; production uses
+	// GoogleEndpoint and tests a fake.
+	Endpoint oauth2.Endpoint
+	// RevokeURL is Google's revocation endpoint; production uses
+	// GoogleRevokeURL and tests a fake.
+	RevokeURL string
+}
+
+// Service connects and disconnects the household's Google account.
+type Service struct {
+	st        *store.Store
+	box       *secretbox.Box
+	oauth     oauth2.Config
+	revokeURL string
+	client    *http.Client
+	cookie    auth.FlowCookie
+	// now is the clock; tests replace it.
+	now func() time.Time
+}
+
+// NewService returns the service over st, sealing refresh tokens with box.
+func NewService(st *store.Store, box *secretbox.Box, cfg Config) (*Service, error) {
+	switch {
+	case st == nil:
+		return nil, errors.New("gcal: nil store")
+	case box == nil:
+		return nil, errors.New("gcal: nil secret box")
+	case cfg.ClientID == "", cfg.ClientSecret == "":
+		return nil, errors.New("gcal: client ID and client secret are required")
+	case cfg.PublicURL == nil:
+		return nil, errors.New("gcal: public URL is required")
+	case len(cfg.SecretKey) == 0:
+		return nil, errors.New("gcal: secret key is required")
+	case cfg.Endpoint.AuthURL == "", cfg.Endpoint.TokenURL == "", cfg.RevokeURL == "":
+		return nil, errors.New("gcal: authorization, token and revoke endpoints are required")
+	}
+	return &Service{
+		st:  st,
+		box: box,
+		oauth: oauth2.Config{
+			ClientID:     cfg.ClientID,
+			ClientSecret: cfg.ClientSecret,
+			Endpoint:     cfg.Endpoint,
+			RedirectURL:  cfg.PublicURL.Scheme + "://" + cfg.PublicURL.Host + CallbackPath,
+			Scopes:       slices.Clone(Scopes),
+		},
+		revokeURL: cfg.RevokeURL,
+		client:    &http.Client{Timeout: googleTimeout, CheckRedirect: auth.CheckRedirect},
+		cookie:    auth.NewFlowCookie(connectCookieName, connectCookieKeyLabel, connectCookieTTL, cfg.SecretKey),
+		now:       time.Now,
+	}, nil
+}
+
+// connectState travels from Connect to Complete in the signed connect
+// cookie.
+type connectState struct {
+	State    string `json:"s"`
+	Verifier string `json:"v"`
+	// Session binds the state to the session that started the connect: the
+	// SHA-256 of its CSRF token, which is unique to the session and never
+	// changes during it.
+	Session string `json:"b"`
+	auth.FlowExpiry
+}
+
+// sessionBinding is the value connectState.Session must hold for s.
+func sessionBinding(s auth.Session) string {
+	sum := sha256.Sum256([]byte(s.CSRFToken))
+	return hex.EncodeToString(sum[:])
+}
+
+// Connect sets the connect cookie on w, bound to session, and returns
+// Google's consent URL: offline access, consent always prompted so Google
+// always issues a refresh token, and PKCE (S256).
+func (s *Service) Connect(w http.ResponseWriter, session auth.Session) (string, error) {
+	if session.CSRFToken == "" {
+		return "", errors.New("gcal: connect needs a session")
+	}
+	state := connectState{
+		State:    rand.Text(),
+		Verifier: oauth2.GenerateVerifier(),
+		Session:  sessionBinding(session),
+	}
+	if err := s.cookie.Set(w, &state, s.now()); err != nil {
+		return "", fmt.Errorf("gcal: set connect cookie: %w", err)
+	}
+	return s.oauth.AuthCodeURL(state.State,
+		oauth2.AccessTypeOffline,
+		oauth2.ApprovalForce,
+		oauth2.S256ChallengeOption(state.Verifier),
+	), nil
+}
+
+// Complete finishes the connect Google redirected r back with. It clears the
+// connect cookie, checks the state against it and session, exchanges the
+// code and stores the refresh token, sealed, with connected_at now. A
+// reconnect replaces the stored token and keeps the chosen calendar.
+func (s *Service) Complete(w http.ResponseWriter, r *http.Request, session auth.Session) error {
+	ctx := r.Context()
+	// The connect cookie is single-use.
+	s.cookie.Clear(w)
+
+	var state connectState
+	if err := s.cookie.Read(r, &state, s.now()); err != nil {
+		return fmt.Errorf("%w: %v", ErrBadState, err)
+	}
+	q := r.URL.Query()
+	if subtle.ConstantTimeCompare([]byte(q.Get("state")), []byte(state.State)) != 1 {
+		return fmt.Errorf("%w: state mismatch", ErrBadState)
+	}
+	if subtle.ConstantTimeCompare([]byte(sessionBinding(session)), []byte(state.Session)) != 1 {
+		return fmt.Errorf("%w: started by another session", ErrBadState)
+	}
+	if q.Get("error") != "" {
+		// error and error_description are Google-supplied text; neither is
+		// kept.
+		return ErrDenied
+	}
+	code := q.Get("code")
+	if code == "" {
+		return ErrNoCode
+	}
+
+	token, err := s.oauth.Exchange(context.WithValue(ctx, oauth2.HTTPClient, s.client), code,
+		oauth2.VerifierOption(state.Verifier))
+	if err != nil {
+		return fmt.Errorf("gcal: %w", auth.ExchangeError(err))
+	}
+	if token.RefreshToken == "" {
+		return ErrNoRefreshToken
+	}
+	if err := checkScopes(token); err != nil {
+		return err
+	}
+	sealed, err := s.box.Encrypt([]byte(token.RefreshToken))
+	if err != nil {
+		return fmt.Errorf("gcal: seal refresh token: %w", err)
+	}
+	return s.store(ctx, sealed)
+}
+
+// checkScopes fails with ErrScopes unless token's granted scopes include
+// every scope in Scopes. Google lets the household untick a permission on
+// the consent screen and reports what was granted in "scope".
+func checkScopes(token *oauth2.Token) error {
+	granted, _ := token.Extra("scope").(string)
+	have := strings.Fields(granted)
+	for _, want := range Scopes {
+		if !slices.Contains(have, want) {
+			return ErrScopes
+		}
+	}
+	return nil
+}
+
+// store saves sealed as the refresh token with connected_at now, clearing
+// any earlier sync error.
+func (s *Service) store(ctx context.Context, sealed []byte) error {
+	return s.st.WithTx(ctx, func(tx *sql.Tx) error {
+		q := db.New(tx)
+		row, err := q.GetIntegrationsGoogle(ctx)
+		exists := err == nil
+		if err != nil && !errors.Is(err, sql.ErrNoRows) {
+			return fmt.Errorf("gcal: read Google integration: %w", err)
+		}
+		now := store.Timestamp{Time: s.now().UTC().Truncate(time.Millisecond)}.String()
+		created := now
+		if exists {
+			created = row.CreatedAt
+		}
+		if _, err := q.UpsertIntegrationsGoogle(ctx, db.UpsertIntegrationsGoogleParams{
+			RefreshTokenCt: sealed,
+			CalendarID:     row.CalendarID,
+			CalendarName:   row.CalendarName,
+			ConnectedAt:    now,
+			CreatedAt:      created,
+			UpdatedAt:      now,
+		}); err != nil {
+			return fmt.Errorf("gcal: save Google integration: %w", err)
+		}
+		return nil
+	})
+}
+
+// Disconnect revokes the stored refresh token at Google, then deletes the
+// connection. A token Google no longer knows (the household already removed
+// MealQuest's access in their Google account) counts as revoked. Any other
+// revoke failure keeps the connection so the household can retry.
+func (s *Service) Disconnect(ctx context.Context) error {
+	row, err := db.New(s.st.Reader).GetIntegrationsGoogle(ctx)
+	if errors.Is(err, sql.ErrNoRows) {
+		return ErrNotConnected
+	}
+	if err != nil {
+		return fmt.Errorf("gcal: read Google integration: %w", err)
+	}
+	token, err := s.box.Decrypt(row.RefreshTokenCt)
+	if err != nil {
+		return fmt.Errorf("gcal: open refresh token: %w", err)
+	}
+	if err := s.revoke(ctx, string(token)); err != nil {
+		return err
+	}
+	n, err := db.New(s.st.Writer).DeleteIntegrationsGoogle(ctx, row.RefreshTokenCt)
+	if err != nil {
+		return fmt.Errorf("gcal: delete Google integration: %w", err)
+	}
+	if n == 0 {
+		return ErrChanged
+	}
+	return nil
+}
+
+// RevokeError is a revoke Google refused or that failed in transit. Its text
+// never holds the token or Google's response body.
+type RevokeError struct {
+	msg string
+}
+
+func (e *RevokeError) Error() string { return e.msg }
+
+// revoke revokes token at Google. HTTP 200 and HTTP 400 invalid_token (the
+// token is already revoked or expired) both leave it unusable.
+func (s *Service) revoke(ctx context.Context, token string) error {
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, s.revokeURL,
+		strings.NewReader(url.Values{"token": {token}}.Encode()))
+	if err != nil {
+		return fmt.Errorf("gcal: build revoke request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	resp, err := s.client.Do(req)
+	if err != nil {
+		var transport *url.Error
+		if errors.As(err, &transport) {
+			// The URL is dropped: after a refused redirect it is the
+			// Google-supplied Location.
+			return &RevokeError{msg: fmt.Sprintf("gcal: revoke request failed: %s: %v", transport.Op, transport.Err)}
+		}
+		return &RevokeError{msg: "gcal: revoke request failed"}
+	}
+	defer resp.Body.Close()
+	body, err := io.ReadAll(io.LimitReader(resp.Body, maxRevokeBody))
+	if err != nil {
+		return &RevokeError{msg: "gcal: read revoke response failed"}
+	}
+	if resp.StatusCode == http.StatusOK {
+		return nil
+	}
+	if resp.StatusCode == http.StatusBadRequest {
+		var reply struct {
+			Error string `json:"error"`
+		}
+		if json.Unmarshal(body, &reply) == nil && reply.Error == "invalid_token" {
+			return nil
+		}
+	}
+	return &RevokeError{msg: fmt.Sprintf("gcal: Google refused the revoke (HTTP %d)", resp.StatusCode)}
+}

internal/gcal/connect_test.go

@@ -0,0 +1,476 @@
+package gcal_test
+
+import (
+	"bytes"
+	"context"
+	"crypto/rand"
+	"database/sql"
+	"encoding/base64"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"slices"
+	"strings"
+	"testing"
+	"time"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/auth"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/db"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/gcal"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/gcal/gcaltest"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/secretbox"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/migrations"
+)
+
+const publicURL = "https://meals.example.com/app"
+
+var (
+	redirectURL = "https://meals.example.com" + gcal.CallbackPath
+	session     = auth.Session{Subject: "user-1", CSRFToken: "csrf-session-one"}
+	other       = auth.Session{Subject: "user-1", CSRFToken: "csrf-session-two"}
+)
+
+type harness struct {
+	svc    *gcal.Service
+	google *gcaltest.Google
+	st     *store.Store
+	box    *secretbox.Box
+	clock  time.Time
+}
+
+func newHarness(t *testing.T) *harness {
+	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)
+	}
+	key := make([]byte, secretbox.KeySize)
+	rand.Read(key)
+	box, err := secretbox.New(base64.StdEncoding.EncodeToString(key))
+	if err != nil {
+		t.Fatal(err)
+	}
+	pub, err := url.Parse(publicURL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	google := gcaltest.New(t, redirectURL)
+	svc, err := gcal.NewService(st, box, gcal.Config{
+		ClientID:     gcaltest.ClientID,
+		ClientSecret: gcaltest.ClientSecret,
+		PublicURL:    pub,
+		SecretKey:    []byte("server-secret-key"),
+		Endpoint:     google.Endpoint(),
+		RevokeURL:    google.RevokeURL(),
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	h := &harness{svc: svc, google: google, st: st, box: box, clock: time.Date(2026, 10, 7, 18, 30, 0, 0, time.UTC)}
+	gcal.SetClock(svc, func() time.Time { return h.clock })
+	return h
+}
+
+// connect is a started connect: Google's consent URL and the connect
+// cookie.
+type connect struct {
+	consent *url.URL
+	cookie  *http.Cookie
+}
+
+func (h *harness) connect(t *testing.T, s auth.Session) connect {
+	t.Helper()
+	rec := httptest.NewRecorder()
+	raw, err := h.svc.Connect(rec, s)
+	if err != nil {
+		t.Fatal(err)
+	}
+	consent, err := url.Parse(raw)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cookies := rec.Result().Cookies()
+	if len(cookies) != 1 {
+		t.Fatalf("Connect set %d cookies, want 1", len(cookies))
+	}
+	return connect{consent: consent, cookie: cookies[0]}
+}
+
+// callback completes c as session s with query, returning the error and the
+// recorder Complete wrote to.
+func (h *harness) callback(c connect, s auth.Session, query url.Values) (*httptest.ResponseRecorder, error) {
+	req := httptest.NewRequest(http.MethodGet, gcal.CallbackPath+"?"+query.Encode(), nil)
+	if c.cookie != nil {
+		req.AddCookie(c.cookie)
+	}
+	rec := httptest.NewRecorder()
+	return rec, h.svc.Complete(rec, req, s)
+}
+
+// consented is the query Google sends back after consent to c.
+func (h *harness) consented(c connect) url.Values {
+	q := c.consent.Query()
+	return url.Values{"state": {q.Get("state")}, "code": {h.google.Authorize(q.Get("code_challenge"))}}
+}
+
+func (h *harness) row(t *testing.T) (db.IntegrationsGoogle, bool) {
+	t.Helper()
+	row, err := db.New(h.st.Reader).GetIntegrationsGoogle(context.Background())
+	if errors.Is(err, sql.ErrNoRows) {
+		return db.IntegrationsGoogle{}, false
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+	return row, true
+}
+
+func TestConnectRedirectsToConsent(t *testing.T) {
+	t.Parallel()
+	h := newHarness(t)
+	c := h.connect(t, session)
+
+	if got, want := c.consent.Scheme+"://"+c.consent.Host+c.consent.Path, h.google.Endpoint().AuthURL; got != want {
+		t.Errorf("consent URL = %s, want %s", got, want)
+	}
+	q := c.consent.Query()
+	for name, want := range map[string]string{
+		"client_id":             gcaltest.ClientID,
+		"redirect_uri":          redirectURL,
+		"response_type":         "code",
+		"access_type":           "offline",
+		"prompt":                "consent",
+		"code_challenge_method": "S256",
+	} {
+		if got := q.Get(name); got != want {
+			t.Errorf("%s = %q, want %q", name, got, want)
+		}
+	}
+	if got := strings.Fields(q.Get("scope")); !slices.Equal(got, []string{
+		"https://www.googleapis.com/auth/calendar.events",
+		"https://www.googleapis.com/auth/calendar.calendarlist.readonly",
+	}) {
+		t.Errorf("scope = %q", q.Get("scope"))
+	}
+	if q.Get("state") == "" || q.Get("code_challenge") == "" {
+		t.Errorf("state %q, code_challenge %q: want both set", q.Get("state"), q.Get("code_challenge"))
+	}
+	if q.Get("client_secret") != "" || strings.Contains(c.consent.String(), gcaltest.ClientSecret) {
+		t.Error("consent URL carries the client secret")
+	}
+
+	ck := c.cookie
+	if ck.Name != "__Host-mealquest_google" || ck.Path != "/" || !ck.Secure || !ck.HttpOnly ||
+		ck.SameSite != http.SameSiteLaxMode || ck.MaxAge != 600 || ck.Domain != "" {
+		t.Errorf("connect cookie = %+v, want __Host-, Path=/, Secure, HttpOnly, Lax, 10 minutes", ck)
+	}
+	// Two connects never share a state.
+	if again := h.connect(t, session); again.consent.Query().Get("state") == q.Get("state") {
+		t.Error("two connects share a state")
+	}
+}
+
+func TestCompleteStoresSealedRefreshToken(t *testing.T) {
+	t.Parallel()
+	h := newHarness(t)
+	c := h.connect(t, session)
+	rec, err := h.callback(c, session, h.consented(c))
+	if err != nil {
+		t.Fatalf("Complete: %v", err)
+	}
+
+	row, ok := h.row(t)
+	if !ok {
+		t.Fatal("no integration stored")
+	}
+	if bytes.Contains(row.RefreshTokenCt, []byte(gcaltest.RefreshToken)) {
+		t.Error("refresh token stored in plain text")
+	}
+	plain, err := h.box.Decrypt(row.RefreshTokenCt)
+	if err != nil || string(plain) != gcaltest.RefreshToken {
+		t.Errorf("stored token opens to %q, %v; want the refresh token", plain, err)
+	}
+	if want := "2026-10-07T18:30:00.000Z"; row.ConnectedAt != want || row.CreatedAt != want || row.UpdatedAt != want {
+		t.Errorf("connected_at %q created_at %q updated_at %q, want %s", row.ConnectedAt, row.CreatedAt, row.UpdatedAt, want)
+	}
+	if row.CalendarID.Valid || row.CalendarName.Valid || row.LastSyncError.Valid {
+		t.Errorf("new connection has calendar or sync error: %+v", row)
+	}
+	assertCookieCleared(t, rec)
+	assertNoSecret(t, "response", rec.Body.String()+headerText(rec.Header()))
+}
+
+func TestReconnectReplacesTokenAndKeepsCalendar(t *testing.T) {
+	t.Parallel()
+	h := newHarness(t)
+	ctx := context.Background()
+	if _, err := db.New(h.st.Writer).UpsertIntegrationsGoogle(ctx, db.UpsertIntegrationsGoogleParams{
+		RefreshTokenCt: []byte("old sealed token"),
+		CalendarID:     sql.NullString{String: "family@group.calendar.google.com", Valid: true},
+		CalendarName:   sql.NullString{String: "Family", Valid: true},
+		ConnectedAt:    "2026-09-01T00:00:00.000Z",
+		LastSyncError:  sql.NullString{String: "token revoked", Valid: true},
+		CreatedAt:      "2026-09-01T00:00:00.000Z",
+		UpdatedAt:      "2026-09-01T00:00:00.000Z",
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	c := h.connect(t, session)
+	if _, err := h.callback(c, session, h.consented(c)); err != nil {
+		t.Fatalf("Complete: %v", err)
+	}
+	row, _ := h.row(t)
+	if plain, err := h.box.Decrypt(row.RefreshTokenCt); err != nil || string(plain) != gcaltest.RefreshToken {
+		t.Errorf("token after reconnect opens to %q, %v", plain, err)
+	}
+	if row.CalendarID.String != "family@group.calendar.google.com" || row.CalendarName.String != "Family" {
+		t.Errorf("calendar after reconnect = %v %v, want it kept", row.CalendarID, row.CalendarName)
+	}
+	if row.LastSyncError.Valid {
+		t.Errorf("last_sync_error = %q, want it cleared", row.LastSyncError.String)
+	}
+	if row.CreatedAt != "2026-09-01T00:00:00.000Z" || row.ConnectedAt != "2026-10-07T18:30:00.000Z" {
+		t.Errorf("created_at %q connected_at %q", row.CreatedAt, row.ConnectedAt)
+	}
+}
+
+func TestCompleteRefusesBadState(t *testing.T) {
+	t.Parallel()
+	for _, tc := range []struct {
+		name string
+		// edit changes the connect, the callback's session or its query.
+		edit func(t *testing.T, h *harness, c *connect, s *auth.Session, q url.Values)
+	}{
+		{"missing state", func(_ *testing.T, _ *harness, _ *connect, _ *auth.Session, q url.Values) { q.Del("state") }},
+		{"wrong state", func(_ *testing.T, _ *harness, _ *connect, _ *auth.Session, q url.Values) { q.Set("state", "forged") }},
+		{"no connect cookie", func(_ *testing.T, _ *harness, c *connect, _ *auth.Session, _ url.Values) { c.cookie = nil }},
+		{"tampered cookie", func(_ *testing.T, _ *harness, c *connect, _ *auth.Session, _ url.Values) {
+			c.cookie = &http.Cookie{Name: c.cookie.Name, Value: "x" + c.cookie.Value}
+		}},
+		{"another session", func(_ *testing.T, _ *harness, _ *connect, s *auth.Session, _ url.Values) { *s = other }},
+		{"expired", func(_ *testing.T, h *harness, _ *connect, _ *auth.Session, _ url.Values) {
+			h.clock = h.clock.Add(10 * time.Minute)
+		}},
+		{"state of another connect", func(t *testing.T, h *harness, _ *connect, _ *auth.Session, q url.Values) {
+			q.Set("state", h.connect(t, session).consent.Query().Get("state"))
+		}},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			h := newHarness(t)
+			c := h.connect(t, session)
+			s := session
+			q := h.consented(c)
+			tc.edit(t, h, &c, &s, q)
+
+			rec, err := h.callback(c, s, q)
+			if !errors.Is(err, gcal.ErrBadState) {
+				t.Fatalf("Complete error = %v, want ErrBadState", err)
+			}
+			if h.google.TokenCalls() != 0 {
+				t.Error("the code was exchanged despite the bad state")
+			}
+			if _, ok := h.row(t); ok {
+				t.Error("an integration was stored")
+			}
+			assertCookieCleared(t, rec)
+		})
+	}
+}
+
+func TestCompleteRefusesMissingRefreshToken(t *testing.T) {
+	t.Parallel()
+	h := newHarness(t)
+	h.google.OmitRefreshToken()
+	c := h.connect(t, session)
+	_, err := h.callback(c, session, h.consented(c))
+	if !errors.Is(err, gcal.ErrNoRefreshToken) {
+		t.Fatalf("Complete error = %v, want ErrNoRefreshToken", err)
+	}
+	if _, ok := h.row(t); ok {
+		t.Error("an integration was stored without a refresh token")
+	}
+	assertNoSecret(t, "error", err.Error())
+}
+
+func TestCompleteRefusesMissingScope(t *testing.T) {
+	t.Parallel()
+	h := newHarness(t)
+	h.google.GrantScope("https://www.googleapis.com/auth/calendar.calendarlist.readonly")
+	c := h.connect(t, session)
+	_, err := h.callback(c, session, h.consented(c))
+	if !errors.Is(err, gcal.ErrScopes) {
+		t.Fatalf("Complete error = %v, want ErrScopes", err)
+	}
+	if _, ok := h.row(t); ok {
+		t.Error("an integration was stored without calendar.events")
+	}
+}
+
+func TestCompleteDenied(t *testing.T) {
+	t.Parallel()
+	h := newHarness(t)
+	c := h.connect(t, session)
+	q := url.Values{"state": {c.consent.Query().Get("state")}, "error": {"access_denied"}}
+	if _, err := h.callback(c, session, q); !errors.Is(err, gcal.ErrDenied) {
+		t.Fatalf("Complete error = %v, want ErrDenied", err)
+	}
+	if h.google.TokenCalls() != 0 {
+		t.Error("token endpoint called after a denial")
+	}
+}
+
+func TestCompleteExchangeFailureIsRedacted(t *testing.T) {
+	t.Parallel()
+	h := newHarness(t)
+	h.google.FailToken(http.StatusBadRequest)
+	c := h.connect(t, session)
+	_, err := h.callback(c, session, h.consented(c))
+	if err == nil {
+		t.Fatal("Complete succeeded despite the token endpoint failing")
+	}
+	if !strings.Contains(err.Error(), "HTTP 400") {
+		t.Errorf("error = %v, want the status", err)
+	}
+	assertNoSecret(t, "error", err.Error())
+	if _, ok := h.row(t); ok {
+		t.Error("an integration was stored")
+	}
+}
+
+func TestDisconnectRevokesAndClears(t *testing.T) {
+	t.Parallel()
+	h := newHarness(t)
+	c := h.connect(t, session)
+	if _, err := h.callback(c, session, h.consented(c)); err != nil {
+		t.Fatal(err)
+	}
+	if err := h.svc.Disconnect(context.Background()); err != nil {
+		t.Fatalf("Disconnect: %v", err)
+	}
+	if got := h.google.Revoked(); !slices.Equal(got, []string{gcaltest.RefreshToken}) {
+		t.Errorf("revoked %q, want the refresh token", got)
+	}
+	if _, ok := h.row(t); ok {
+		t.Error("integration still stored after disconnect")
+	}
+	if err := h.svc.Disconnect(context.Background()); !errors.Is(err, gcal.ErrNotConnected) {
+		t.Errorf("second Disconnect = %v, want ErrNotConnected", err)
+	}
+}
+
+func TestDisconnectTokenAlreadyRevokedAtGoogle(t *testing.T) {
+	t.Parallel()
+	h := newHarness(t)
+	c := h.connect(t, session)
+	if _, err := h.callback(c, session, h.consented(c)); err != nil {
+		t.Fatal(err)
+	}
+	h.google.AnswerRevoke(http.StatusBadRequest, `{"error":"invalid_token","error_description":"Token expired or revoked"}`)
+	if err := h.svc.Disconnect(context.Background()); err != nil {
+		t.Fatalf("Disconnect: %v", err)
+	}
+	if _, ok := h.row(t); ok {
+		t.Error("integration still stored")
+	}
+}
+
+func TestDisconnectRevokeFailureKeepsConnection(t *testing.T) {
+	t.Parallel()
+	for _, status := range []int{http.StatusBadRequest, http.StatusServiceUnavailable} {
+		h := newHarness(t)
+		c := h.connect(t, session)
+		if _, err := h.callback(c, session, h.consented(c)); err != nil {
+			t.Fatal(err)
+		}
+		h.google.AnswerRevoke(status, "")
+		err := h.svc.Disconnect(context.Background())
+		var revoke *gcal.RevokeError
+		if !errors.As(err, &revoke) {
+			t.Fatalf("HTTP %d: Disconnect error = %v, want *RevokeError", status, err)
+		}
+		assertNoSecret(t, "error", err.Error())
+		if _, ok := h.row(t); !ok {
+			t.Errorf("HTTP %d: connection cleared although Google did not revoke", status)
+		}
+	}
+}
+
+func TestDisconnectNotConnected(t *testing.T) {
+	t.Parallel()
+	h := newHarness(t)
+	if err := h.svc.Disconnect(context.Background()); !errors.Is(err, gcal.ErrNotConnected) {
+		t.Fatalf("Disconnect = %v, want ErrNotConnected", err)
+	}
+	if len(h.google.Revoked()) != 0 {
+		t.Error("revoke called with nothing connected")
+	}
+}
+
+func TestNewServiceRequiresConfig(t *testing.T) {
+	t.Parallel()
+	h := newHarness(t)
+	pub, _ := url.Parse(publicURL)
+	valid := gcal.Config{
+		ClientID: "id", ClientSecret: "secret", PublicURL: pub, SecretKey: []byte("k"),
+		Endpoint: gcal.GoogleEndpoint, RevokeURL: gcal.GoogleRevokeURL,
+	}
+	if _, err := gcal.NewService(h.st, h.box, valid); err != nil {
+		t.Fatalf("valid config: %v", err)
+	}
+	for name, edit := range map[string]func(*gcal.Config){
+		"client ID":     func(c *gcal.Config) { c.ClientID = "" },
+		"client secret": func(c *gcal.Config) { c.ClientSecret = "" },
+		"public URL":    func(c *gcal.Config) { c.PublicURL = nil },
+		"secret key":    func(c *gcal.Config) { c.SecretKey = nil },
+		"token URL":     func(c *gcal.Config) { c.Endpoint.TokenURL = "" },
+		"revoke URL":    func(c *gcal.Config) { c.RevokeURL = "" },
+	} {
+		cfg := valid
+		edit(&cfg)
+		if _, err := gcal.NewService(h.st, h.box, cfg); err == nil {
+			t.Errorf("NewService accepted a config without the %s", name)
+		}
+	}
+}
+
+func assertCookieCleared(t *testing.T, rec *httptest.ResponseRecorder) {
+	t.Helper()
+	for _, c := range rec.Result().Cookies() {
+		if c.Name == "__Host-mealquest_google" && c.MaxAge < 0 {
+			return
+		}
+	}
+	t.Error("connect cookie not cleared")
+}
+
+// assertNoSecret fails when text holds the refresh token, the access token
+// or the client secret.
+func assertNoSecret(t *testing.T, what, text string) {
+	t.Helper()
+	for _, secret := range []string{gcaltest.RefreshToken, gcaltest.AccessToken, gcaltest.ClientSecret} {
+		if strings.Contains(text, secret) {
+			t.Errorf("%s contains a secret: %s", what, text)
+		}
+	}
+}
+
+func headerText(h http.Header) string {
+	var b strings.Builder
+	for k, vs := range h {
+		b.WriteString(k + ": " + strings.Join(vs, ", ") + "\n")
+	}
+	return b.String()
+}

internal/gcal/export_test.go

@@ -0,0 +1,6 @@
+package gcal
+
+import "time"
+
+// SetClock replaces s's clock.
+func SetClock(s *Service, now func() time.Time) { s.now = now }

internal/gcal/gcaltest/gcaltest.go

@@ -0,0 +1,209 @@
+// Package gcaltest provides a fake Google OAuth server for tests of the
+// Google Calendar connection: a token endpoint that checks the client, the
+// redirect URI and PKCE, and a revoke endpoint that records what it revoked.
+// It never touches the network beyond its own httptest server.
+package gcaltest
+
+import (
+	"crypto/sha256"
+	"encoding/base64"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"sync"
+	"testing"
+
+	"golang.org/x/oauth2"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/gcal"
+)
+
+// Fixed credentials and tokens the fake issues and expects.
+const (
+	ClientID     = "mealquest-test.apps.googleusercontent.com"
+	ClientSecret = "google-client-s3cret-4f1c"
+	RefreshToken = "1//google-refresh-t0ken-9a8b7c"
+	AccessToken  = "ya29.google-access-t0ken-5d6e"
+)
+
+// Google is the fake. Its exported fields script the next responses; set
+// them before the request they affect.
+type Google struct {
+	Server *httptest.Server
+	// RedirectURL is the redirect URI the token endpoint requires.
+	RedirectURL string
+
+	mu sync.Mutex
+	// omitRefresh leaves refresh_token out of the token response.
+	omitRefresh bool
+	// scope is the token response's granted scopes.
+	scope string
+	// tokenStatus, when not 200, fails the token endpoint with a body that
+	// quotes the refresh token and client secret.
+	tokenStatus int
+	// revokeStatus and revokeBody answer the revoke endpoint; revokeBody
+	// quotes the token when revokeStatus is not 200 or 400.
+	revokeStatus int
+	revokeBody   string
+	codes        map[string]string // code -> PKCE challenge
+	tokenCalls   int
+	revoked      []string
+}
+
+// New starts a fake Google that requires redirectURL at its token endpoint.
+// It grants every scope in gcal.Scopes with a refresh token by default.
+func New(t *testing.T, redirectURL string) *Google {
+	t.Helper()
+	g := &Google{
+		RedirectURL:  redirectURL,
+		scope:        strings.Join(gcal.Scopes, " "),
+		tokenStatus:  http.StatusOK,
+		revokeStatus: http.StatusOK,
+		codes:        map[string]string{},
+	}
+	mux := http.NewServeMux()
+	mux.HandleFunc("POST /token", g.token)
+	mux.HandleFunc("POST /revoke", g.revoke)
+	g.Server = httptest.NewServer(mux)
+	t.Cleanup(g.Server.Close)
+	return g
+}
+
+// Endpoint is the fake's authorization and token endpoint, with Google's
+// client authentication style.
+func (g *Google) Endpoint() oauth2.Endpoint {
+	return oauth2.Endpoint{
+		AuthURL:   g.Server.URL + "/auth",
+		TokenURL:  g.Server.URL + "/token",
+		AuthStyle: gcal.GoogleEndpoint.AuthStyle,
+	}
+}
+
+// RevokeURL is the fake's revocation endpoint.
+func (g *Google) RevokeURL() string { return g.Server.URL + "/revoke" }
+
+// Authorize plays the consent screen for an authorization request with PKCE
+// challenge and returns the code Google would send back.
+func (g *Google) Authorize(challenge string) string {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	code := fmt.Sprintf("code-%d", len(g.codes)+1)
+	g.codes[code] = challenge
+	return code
+}
+
+// OmitRefreshToken makes the token endpoint answer without a refresh token,
+// as Google does when it reuses an earlier grant.
+func (g *Google) OmitRefreshToken() {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	g.omitRefresh = true
+}
+
+// GrantScope sets the scopes the token endpoint reports as granted.
+func (g *Google) GrantScope(scope string) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	g.scope = scope
+}
+
+// FailToken makes the token endpoint answer status with a body that quotes
+// the refresh token and client secret.
+func (g *Google) FailToken(status int) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	g.tokenStatus = status
+}
+
+// AnswerRevoke makes the revoke endpoint answer status with body. A body of
+// "" with a status other than 200 quotes the token it was sent.
+func (g *Google) AnswerRevoke(status int, body string) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	g.revokeStatus, g.revokeBody = status, body
+}
+
+// TokenCalls is how many requests reached the token endpoint.
+func (g *Google) TokenCalls() int {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	return g.tokenCalls
+}
+
+// Revoked lists the tokens the revoke endpoint received, in order.
+func (g *Google) Revoked() []string {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	return append([]string(nil), g.revoked...)
+}
+
+func (g *Google) token(w http.ResponseWriter, r *http.Request) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	g.tokenCalls++
+	if err := r.ParseForm(); err != nil {
+		http.Error(w, "bad form", http.StatusBadRequest)
+		return
+	}
+	f := r.PostForm
+	challenge, known := g.codes[f.Get("code")]
+	delete(g.codes, f.Get("code"))
+	switch {
+	case f.Get("grant_type") != "authorization_code":
+		oauthError(w, http.StatusBadRequest, "unsupported_grant_type")
+		return
+	case f.Get("client_id") != ClientID || f.Get("client_secret") != ClientSecret:
+		oauthError(w, http.StatusUnauthorized, "invalid_client")
+		return
+	case !known, f.Get("redirect_uri") != g.RedirectURL, s256(f.Get("code_verifier")) != challenge:
+		oauthError(w, http.StatusBadRequest, "invalid_grant")
+		return
+	}
+	if g.tokenStatus != http.StatusOK {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(g.tokenStatus)
+		fmt.Fprintf(w, `{"error":"invalid_grant","error_description":"echo %s %s"}`, RefreshToken, ClientSecret)
+		return
+	}
+	refresh := ""
+	if !g.omitRefresh {
+		refresh = fmt.Sprintf(`"refresh_token":%q,`, RefreshToken)
+	}
+	w.Header().Set("Content-Type", "application/json")
+	fmt.Fprintf(w, `{"access_token":%q,%s"expires_in":3599,"scope":%q,"token_type":"Bearer"}`,
+		AccessToken, refresh, g.scope)
+}
+
+func (g *Google) revoke(w http.ResponseWriter, r *http.Request) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	if r.Header.Get("Content-Type") != "application/x-www-form-urlencoded" {
+		http.Error(w, "want a form", http.StatusUnsupportedMediaType)
+		return
+	}
+	if err := r.ParseForm(); err != nil {
+		http.Error(w, "bad form", http.StatusBadRequest)
+		return
+	}
+	token := r.PostForm.Get("token")
+	g.revoked = append(g.revoked, token)
+	body := g.revokeBody
+	if body == "" && g.revokeStatus != http.StatusOK {
+		body = "cannot revoke " + token
+	}
+	w.WriteHeader(g.revokeStatus)
+	fmt.Fprint(w, body)
+}
+
+func oauthError(w http.ResponseWriter, status int, code string) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	fmt.Fprintf(w, `{"error":%q}`, code)
+}
+
+// s256 is the PKCE S256 challenge for verifier.
+func s256(verifier string) string {
+	sum := sha256.Sum256([]byte(verifier))
+	return base64.RawURLEncoding.EncodeToString(sum[:])
+}

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

internal/server/google.go

@@ -0,0 +1,105 @@
+package server
+
+import (
+	"errors"
+	"log/slog"
+	"net/http"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/auth"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/gcal"
+)
+
+// googleConnectedPath is where a completed connect sends the browser: the
+// Google Calendar settings screen.
+const googleConnectedPath = "/settings/calendar"
+
+// getGoogleConnect sends the browser to Google's consent screen with a state
+// bound to its session. The household opens it as a top-level navigation;
+// the session cookie is SameSite=Lax, so it rides along.
+func getGoogleConnect(logger *slog.Logger, svc *gcal.Service) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Cache-Control", "no-store")
+		session, ok := auth.SessionFrom(r.Context())
+		if !ok {
+			logger.ErrorContext(r.Context(), "Google connect without a session")
+			writeError(w, r, logger, http.StatusInternalServerError, "internal", "internal error")
+			return
+		}
+		consent, err := svc.Connect(w, session)
+		if err != nil {
+			logger.ErrorContext(r.Context(), "start Google connect", "error", err)
+			writeError(w, r, logger, http.StatusInternalServerError, "internal", "internal error")
+			return
+		}
+		http.Redirect(w, r, consent, http.StatusFound)
+	}
+}
+
+// getGoogleCallback completes the connect Google redirects back with, then
+// sends the browser to the Google Calendar settings screen. Every failure is
+// an API error; none holds a token or Google's response text.
+func getGoogleCallback(logger *slog.Logger, svc *gcal.Service) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Cache-Control", "no-store")
+		ctx := r.Context()
+		session, ok := auth.SessionFrom(ctx)
+		if !ok {
+			logger.ErrorContext(ctx, "Google callback without a session")
+			writeError(w, r, logger, http.StatusInternalServerError, "internal", "internal error")
+			return
+		}
+		err := svc.Complete(w, r, session)
+		switch {
+		case err == nil:
+			http.Redirect(w, r, googleConnectedPath, http.StatusSeeOther)
+		case errors.Is(err, gcal.ErrBadState):
+			logger.WarnContext(ctx, "Google callback refused", "error", err)
+			writeError(w, r, logger, http.StatusBadRequest, "invalid_state",
+				"this Google Calendar connection expired or was not started here; connect again")
+		case errors.Is(err, gcal.ErrDenied):
+			logger.WarnContext(ctx, "Google returned an authorization error")
+			writeError(w, r, logger, http.StatusForbidden, "google_denied",
+				"Google did not grant access to your calendar; connect again to retry")
+		case errors.Is(err, gcal.ErrNoCode):
+			writeError(w, r, logger, http.StatusBadRequest, "invalid_request", "missing authorization code")
+		case errors.Is(err, gcal.ErrNoRefreshToken):
+			logger.WarnContext(ctx, "Google connect refused", "error", err)
+			writeError(w, r, logger, http.StatusBadGateway, "reconnect_required",
+				"Google did not grant lasting access to your calendar; connect Google Calendar again")
+		case errors.Is(err, gcal.ErrScopes):
+			logger.WarnContext(ctx, "Google connect refused", "error", err)
+			writeError(w, r, logger, http.StatusForbidden, "scopes_missing",
+				"allow MealQuest to see your calendars and manage their events, then connect Google Calendar again")
+		default:
+			logger.WarnContext(ctx, "Google connect failed", "error", err)
+			writeError(w, r, logger, http.StatusBadGateway, "google_failed",
+				"Google Calendar could not be connected; connect again")
+		}
+	}
+}
+
+// deleteGoogle revokes the connected account's access at Google and forgets
+// it: 204 on success, 409 not_connected when nothing is connected, 502 when
+// Google could not revoke (the connection is kept, so it can be retried).
+func deleteGoogle(logger *slog.Logger, svc *gcal.Service) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		err := svc.Disconnect(r.Context())
+		var revoke *gcal.RevokeError
+		switch {
+		case err == nil:
+			w.WriteHeader(http.StatusNoContent)
+		case errors.Is(err, gcal.ErrNotConnected):
+			writeError(w, r, logger, http.StatusConflict, "not_connected", "Google Calendar is not connected")
+		case errors.Is(err, gcal.ErrChanged):
+			writeError(w, r, logger, http.StatusConflict, "conflict",
+				"the Google Calendar connection changed; reload and try again")
+		case errors.As(err, &revoke):
+			logger.WarnContext(r.Context(), "revoke Google access", "error", err)
+			writeError(w, r, logger, http.StatusBadGateway, "revoke_failed",
+				"Google could not revoke MealQuest's access; try again")
+		default:
+			logger.ErrorContext(r.Context(), "disconnect Google Calendar", "error", err)
+			writeError(w, r, logger, http.StatusInternalServerError, "internal", "internal error")
+		}
+	}
+}

internal/server/google_test.go

@@ -0,0 +1,307 @@
+package server
+
+import (
+	"bytes"
+	"context"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"slices"
+	"strings"
+	"testing"
+	"testing/fstest"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/db"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/gcal"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/gcal/gcaltest"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/secretbox"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
+)
+
+const (
+	googleConnectPath  = "/api/v1/integrations/google/connect"
+	googleCallbackPath = "/api/v1/integrations/google/callback"
+	googlePath         = "/api/v1/integrations/google"
+)
+
+// googleEnv is a router whose Google Calendar service talks to a fake
+// Google, with every log line it writes.
+type googleEnv struct {
+	h      http.Handler
+	google *gcaltest.Google
+	st     *store.Store
+	box    *secretbox.Box
+	logs   *bytes.Buffer
+	// seen collects every response body and header, to check none holds a
+	// secret.
+	seen strings.Builder
+}
+
+func newGoogleEnv(t *testing.T) *googleEnv {
+	t.Helper()
+	pub, err := url.Parse("https://mealquest.example")
+	if err != nil {
+		t.Fatal(err)
+	}
+	e := &googleEnv{
+		google: gcaltest.New(t, "https://mealquest.example"+gcal.CallbackPath),
+		st:     newTestStore(t),
+		box:    newTestBox(t),
+		logs:   &bytes.Buffer{},
+	}
+	svc, err := gcal.NewService(e.st, e.box, gcal.Config{
+		ClientID:     gcaltest.ClientID,
+		ClientSecret: gcaltest.ClientSecret,
+		PublicURL:    pub,
+		SecretKey:    []byte("server-secret-key"),
+		Endpoint:     e.google.Endpoint(),
+		RevokeURL:    e.google.RevokeURL(),
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	logger := slog.New(slog.NewJSONHandler(e.logs, &slog.HandlerOptions{Level: slog.LevelDebug}))
+	e.h, err = NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t),
+		newTestDinners(t), newTestSuggest(t), newTestPlan(t), svc, newTestRunner(t), newTestPhotos(t),
+		fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() {
+		for _, secret := range []string{gcaltest.RefreshToken, gcaltest.AccessToken, gcaltest.ClientSecret} {
+			if strings.Contains(e.seen.String(), secret) {
+				t.Errorf("a response holds a secret: %s", e.seen.String())
+			}
+			if strings.Contains(e.logs.String(), secret) {
+				t.Errorf("the logs hold a secret: %s", e.logs.String())
+			}
+		}
+	})
+	return e
+}
+
+func (e *googleEnv) serve(req *http.Request) *httptest.ResponseRecorder {
+	rec := httptest.NewRecorder()
+	e.h.ServeHTTP(rec, req)
+	e.seen.WriteString(rec.Body.String())
+	for k, vs := range rec.Header() {
+		e.seen.WriteString(k + ": " + strings.Join(vs, ", ") + "\n")
+	}
+	return rec
+}
+
+// connect starts a connect as the test session and returns Google's consent
+// URL and the connect cookie.
+func (e *googleEnv) connect(t *testing.T) (*url.URL, *http.Cookie) {
+	t.Helper()
+	rec := e.serve(signedIn(http.MethodGet, googleConnectPath, nil))
+	if rec.Code != http.StatusFound {
+		t.Fatalf("connect = %d %s, want 302", rec.Code, rec.Body)
+	}
+	if cc := rec.Header().Get("Cache-Control"); cc != "no-store" {
+		t.Errorf("connect Cache-Control = %q, want no-store", cc)
+	}
+	consent, err := url.Parse(rec.Header().Get("Location"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	var cookie *http.Cookie
+	for _, c := range rec.Result().Cookies() {
+		if c.Name == "__Host-mealquest_google" {
+			cookie = c
+		}
+	}
+	if cookie == nil {
+		t.Fatal("connect set no connect cookie")
+	}
+	return consent, cookie
+}
+
+// callback returns to the callback as the test session with the connect
+// cookie and query.
+func (e *googleEnv) callback(cookie *http.Cookie, query url.Values) *httptest.ResponseRecorder {
+	req := httptest.NewRequest(http.MethodGet, googleCallbackPath+"?"+query.Encode(), nil)
+	req.AddCookie(validSessionCookie)
+	if cookie != nil {
+		req.AddCookie(cookie)
+	}
+	return e.serve(req)
+}
+
+func (e *googleEnv) consented(consent *url.URL) url.Values {
+	q := consent.Query()
+	return url.Values{"state": {q.Get("state")}, "code": {e.google.Authorize(q.Get("code_challenge"))}}
+}
+
+func (e *googleEnv) stored(t *testing.T) bool {
+	t.Helper()
+	_, err := db.New(e.st.Reader).GetIntegrationsGoogle(context.Background())
+	if errors.Is(err, sql.ErrNoRows) {
+		return false
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+	return true
+}
+
+func errorBodyCode(t *testing.T, rec *httptest.ResponseRecorder) (code, message string) {
+	t.Helper()
+	var body struct {
+		Error apiError `json:"error"`
+	}
+	if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
+		t.Fatalf("decode %q: %v", rec.Body.String(), err)
+	}
+	return body.Error.Code, body.Error.Message
+}
+
+func TestGoogleConnectAndDisconnect(t *testing.T) {
+	t.Parallel()
+	e := newGoogleEnv(t)
+
+	consent, cookie := e.connect(t)
+	q := consent.Query()
+	if consent.Host != strings.TrimPrefix(e.google.Server.URL, "http://") || consent.Path != "/auth" {
+		t.Errorf("consent URL = %s, want the fake's /auth", consent)
+	}
+	if q.Get("access_type") != "offline" || q.Get("prompt") != "consent" ||
+		q.Get("scope") != strings.Join(gcal.Scopes, " ") ||
+		q.Get("redirect_uri") != "https://mealquest.example"+gcal.CallbackPath {
+		t.Errorf("consent query = %v", q)
+	}
+
+	rec := e.callback(cookie, e.consented(consent))
+	if rec.Code != http.StatusSeeOther || rec.Header().Get("Location") != "/settings/calendar" {
+		t.Fatalf("callback = %d Location %q %s, want 303 to /settings/calendar", rec.Code, rec.Header().Get("Location"), rec.Body)
+	}
+	row, err := db.New(e.st.Reader).GetIntegrationsGoogle(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if plain, err := e.box.Decrypt(row.RefreshTokenCt); err != nil || string(plain) != gcaltest.RefreshToken {
+		t.Errorf("stored token opens to %q, %v", plain, err)
+	}
+	if row.ConnectedAt == "" {
+		t.Error("connected_at not set")
+	}
+
+	// DELETE needs the CSRF header like every other write.
+	req := httptest.NewRequest(http.MethodDelete, googlePath, nil)
+	req.AddCookie(validSessionCookie)
+	if rec := e.serve(req); rec.Code != http.StatusForbidden {
+		t.Errorf("DELETE without CSRF = %d, want 403", rec.Code)
+	}
+	if len(e.google.Revoked()) != 0 || !e.stored(t) {
+		t.Fatal("a DELETE without CSRF revoked or cleared the connection")
+	}
+
+	rec = e.serve(signedIn(http.MethodDelete, googlePath, nil))
+	if rec.Code != http.StatusNoContent || rec.Body.Len() != 0 {
+		t.Fatalf("DELETE = %d %q, want 204 with no body", rec.Code, rec.Body)
+	}
+	if got := e.google.Revoked(); !slices.Equal(got, []string{gcaltest.RefreshToken}) {
+		t.Errorf("revoked %q, want the refresh token", got)
+	}
+	if e.stored(t) {
+		t.Error("connection still stored after DELETE")
+	}
+
+	rec = e.serve(signedIn(http.MethodDelete, googlePath, nil))
+	if code, _ := errorBodyCode(t, rec); rec.Code != http.StatusConflict || code != "not_connected" {
+		t.Errorf("second DELETE = %d %s, want 409 not_connected", rec.Code, rec.Body)
+	}
+}
+
+func TestGoogleCallbackBadState(t *testing.T) {
+	t.Parallel()
+	e := newGoogleEnv(t)
+	consent, cookie := e.connect(t)
+	good := e.consented(consent)
+
+	for name, tc := range map[string]struct {
+		cookie *http.Cookie
+		query  url.Values
+	}{
+		"missing state":  {cookie, url.Values{"code": good["code"]}},
+		"wrong state":    {cookie, url.Values{"state": {"forged"}, "code": good["code"]}},
+		"missing cookie": {nil, good},
+	} {
+		rec := e.callback(tc.cookie, tc.query)
+		if code, _ := errorBodyCode(t, rec); rec.Code != http.StatusBadRequest || code != "invalid_state" {
+			t.Errorf("%s: callback = %d %s, want 400 invalid_state", name, rec.Code, rec.Body)
+		}
+	}
+	if e.google.TokenCalls() != 0 {
+		t.Error("a code was exchanged despite a bad state")
+	}
+	if e.stored(t) {
+		t.Error("a connection was stored")
+	}
+}
+
+func TestGoogleCallbackWithoutRefreshTokenAsksToReconnect(t *testing.T) {
+	t.Parallel()
+	e := newGoogleEnv(t)
+	e.google.OmitRefreshToken()
+	consent, cookie := e.connect(t)
+	rec := e.callback(cookie, e.consented(consent))
+	code, message := errorBodyCode(t, rec)
+	if rec.Code != http.StatusBadGateway || code != "reconnect_required" || !strings.Contains(message, "connect Google Calendar again") {
+		t.Errorf("callback = %d %s, want 502 reconnect_required asking to connect again", rec.Code, rec.Body)
+	}
+	if e.stored(t) {
+		t.Error("a connection was stored without a refresh token")
+	}
+}
+
+func TestGoogleCallbackFailuresAreRedacted(t *testing.T) {
+	t.Parallel()
+	e := newGoogleEnv(t)
+	e.google.FailToken(http.StatusBadRequest)
+	consent, cookie := e.connect(t)
+	rec := e.callback(cookie, e.consented(consent))
+	if code, _ := errorBodyCode(t, rec); rec.Code != http.StatusBadGateway || code != "google_failed" {
+		t.Errorf("callback = %d %s, want 502 google_failed", rec.Code, rec.Body)
+	}
+	// newGoogleEnv's cleanup checks the response and logs hold no secret.
+}
+
+func TestGoogleRevokeFailureKeepsConnection(t *testing.T) {
+	t.Parallel()
+	e := newGoogleEnv(t)
+	consent, cookie := e.connect(t)
+	if rec := e.callback(cookie, e.consented(consent)); rec.Code != http.StatusSeeOther {
+		t.Fatalf("callback = %d %s", rec.Code, rec.Body)
+	}
+	e.google.AnswerRevoke(http.StatusServiceUnavailable, "")
+	rec := e.serve(signedIn(http.MethodDelete, googlePath, nil))
+	if code, _ := errorBodyCode(t, rec); rec.Code != http.StatusBadGateway || code != "revoke_failed" {
+		t.Errorf("DELETE = %d %s, want 502 revoke_failed", rec.Code, rec.Body)
+	}
+	if !e.stored(t) {
+		t.Error("connection cleared although Google did not revoke")
+	}
+}
+
+func TestGoogleRoutesRequireSession(t *testing.T) {
+	t.Parallel()
+	e := newGoogleEnv(t)
+	for _, c := range []struct{ method, path string }{
+		{http.MethodGet, googleConnectPath},
+		{http.MethodGet, googleCallbackPath + "?state=s&code=c"},
+		{http.MethodDelete, googlePath},
+	} {
+		rec := e.serve(httptest.NewRequest(c.method, c.path, nil))
+		if rec.Code != http.StatusUnauthorized || rec.Body.String() != unauthenticatedJSON {
+			t.Errorf("%s %s signed out = %d %s, want 401", c.method, c.path, rec.Code, rec.Body)
+		}
+	}
+	if e.google.TokenCalls() != 0 || len(e.google.Revoked()) != 0 {
+		t.Error("a signed-out request reached Google")
+	}
+}

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), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestGoogle(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), newTestRunner(t),
+	r, err = NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestGoogle(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), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestGoogle(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)
 	}

internal/server/plans_test.go

@@ -56,7 +56,7 @@ func newPlansRouter(t *testing.T) plansEnv {
 		t.Fatal(err)
 	}
 	h, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), newTestSearch(t), newTestAI(t),
-		newTestDinners(t), newTestSuggest(t), svc, runner, newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		newTestDinners(t), newTestSuggest(t), svc, newTestGoogle(t), runner, newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)
 	}

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), newTestRunner(t),
+	r, err := NewRouter(logger, "dev", nil, stubAuth{}, stubSessions{}, newTestSettings(t), search, newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestGoogle(t), newTestRunner(t),
 		newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)

internal/server/server.go

@@ -14,6 +14,7 @@ import (
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/dinners"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/forwarded"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/frontend"
+	"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/plan"
@@ -45,12 +46,14 @@ type RouteMounter interface {
 // /decline; planSvc serves GET /api/v1/plans/{weekStart}, POST
 // /api/v1/plans/{weekStart}/draft, PUT
 // /api/v1/plans/{weekStart}/days/{date}, GET /api/v1/rotation-reviews and
-// POST /api/v1/dinners/{id}/rotation-review; runner serves
+// POST /api/v1/dinners/{id}/rotation-review; googleSvc serves GET
+// /api/v1/integrations/google/connect and /callback and DELETE
+// /api/v1/integrations/google; 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, 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, googleSvc *gcal.Service, runner *jobs.Runner, photos PhotoFiles, assets fs.FS) (http.Handler, error) {
 	if settings == nil {
 		return nil, errors.New("server: nil household settings service")
 	}
@@ -69,6 +72,9 @@ func NewRouter(logger *slog.Logger, version string, trusted forwarded.Trusted, a
 	if planSvc == nil {
 		return nil, errors.New("server: nil plan service")
 	}
+	if googleSvc == nil {
+		return nil, errors.New("server: nil Google Calendar service")
+	}
 	if runner == nil {
 		return nil, errors.New("server: nil job runner")
 	}
@@ -128,6 +134,12 @@ func NewRouter(logger *slog.Logger, version string, trusted forwarded.Trusted, a
 	apiV1.Put("/plans/{weekStart}/days/{date}", putPlanDay(logger, planSvc))
 	apiV1.Get("/rotation-reviews", getRotationReviews(logger, planSvc))
 	apiV1.Post("/dinners/{id}/rotation-review", postRotationReview(logger, planSvc))
+	// connect and callback are top-level browser navigations, so they are
+	// GETs: the Lax session cookie rides both and CSRF applies to neither.
+	// The callback's state is bound to the session that started connect.
+	apiV1.Get("/integrations/google/connect", getGoogleConnect(logger, googleSvc))
+	apiV1.Get("/integrations/google/callback", getGoogleCallback(logger, googleSvc))
+	apiV1.Delete("/integrations/google", deleteGoogle(logger, googleSvc))
 	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

@@ -11,16 +11,19 @@ import (
 	"maps"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"strings"
 	"testing"
 	"testing/fstest"
 
 	"github.com/go-chi/chi/v5"
+	"golang.org/x/oauth2"
 
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/ai/aisettings"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/ai/llm"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/ai/skills"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/dinners"
+	"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/plan"
@@ -50,7 +53,7 @@ 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), runner, newTestPhotos(t), assets)
+	r, err := NewRouter(logger, version, nil, stubAuth{}, stubSessions{}, settings, newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestGoogle(t), runner, newTestPhotos(t), assets)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -218,6 +221,28 @@ func newTestBox(t *testing.T) *secretbox.Box {
 	return box
 }
 
+// newTestGoogle returns a Google Calendar service over a migrated temp
+// database whose Google endpoints refuse every connection.
+func newTestGoogle(t *testing.T) *gcal.Service {
+	t.Helper()
+	pub, err := url.Parse("https://mealquest.example")
+	if err != nil {
+		t.Fatal(err)
+	}
+	svc, err := gcal.NewService(newTestStore(t), newTestBox(t), gcal.Config{
+		ClientID:     "client-id",
+		ClientSecret: "client-secret",
+		PublicURL:    pub,
+		SecretKey:    []byte("server-secret-key"),
+		Endpoint:     oauth2.Endpoint{AuthURL: "http://127.0.0.1:1/auth", TokenURL: "http://127.0.0.1:1/token"},
+		RevokeURL:    "http://127.0.0.1:1/revoke",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	return svc
+}
+
 // newTestAI returns an AI settings service over a migrated temp database
 // with the seed AI settings and a random secret box.
 func newTestAI(t *testing.T) *aisettings.Service {
@@ -237,7 +262,7 @@ 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), 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), newTestGoogle(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil AI settings service")
 	}
 }
@@ -246,7 +271,7 @@ 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), 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), newTestGoogle(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil recipe search settings service")
 	}
 }
@@ -255,7 +280,7 @@ 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), 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), newTestGoogle(t), newTestRunner(t), nil, fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted nil photo files")
 	}
 }
@@ -264,7 +289,7 @@ 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), 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), newTestGoogle(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil settings service")
 	}
 }
@@ -273,7 +298,7 @@ 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), 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), newTestGoogle(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil dinners service")
 	}
 }
@@ -282,7 +307,7 @@ 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), 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), newTestGoogle(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil suggestions service")
 	}
 }
@@ -291,16 +316,25 @@ 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, 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, newTestGoogle(t), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
 		t.Fatal("NewRouter accepted a nil plan service")
 	}
 }
 
+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), nil, newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {}}); err == nil {
+		t.Fatal("NewRouter accepted a nil Google Calendar service")
+	}
+}
+
 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), 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), newTestGoogle(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), newTestRunner(t), newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		newTestSearch(t), newTestAI(t), newTestDinners(t), newTestSuggest(t), newTestPlan(t), newTestGoogle(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), runner, newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
+		newTestDinners(t), svc, newTestPlan(t), newTestGoogle(t), runner, newTestPhotos(t), fstest.MapFS{"index.html": {Data: []byte(fixtureIndex)}})
 	if err != nil {
 		t.Fatal(err)
 	}

migrations/queries/settings.sql

@@ -106,6 +106,13 @@ ON CONFLICT (id) DO UPDATE SET
 	updated_at = excluded.updated_at
 RETURNING *;
 
+-- name: DeleteIntegrationsGoogle :execrows
+-- Deletes the row only while it still holds refresh_token_ct, so a
+-- connection made after the caller read the row is kept. Returns the number
+-- of rows deleted.
+DELETE FROM integrations_google
+WHERE id = 1 AND refresh_token_ct = ?;
+
 -- name: GetChatSettings :one
 -- Returns sql.ErrNoRows until the row exists.
 SELECT * FROM chat_settings