diff --git a/docs/services/authentication.md b/docs/services/authentication.md
index 3b31195..45a7ef1 100644
--- a/docs/services/authentication.md
+++ b/docs/services/authentication.md
@@ -75,10 +75,10 @@ This fragment belongs in `config/auth.yaml`. With the block unset the cookie is
 | `auth.cookie.name` | `token` | Cookie name. |
 | `auth.cookie.domain` | empty (host-only) | A parent domain shares the cookie with its subdomains. |
 | `auth.cookie.path` | `/` | Cookie path. |
-| `auth.cookie.secure` | true when `app.url` is https | `false` is refused in the production environment. |
+| `auth.cookie.secure` | true when `app.url` is https | In the production environment a value that resolves to false is refused, whether `false` is set or inferred from an http or unset `app.url`. |
 | `auth.cookie.same_site` | `lax` | `lax`, `strict` or `none`; `none` requires Secure. |
 
-An invalid domain, `same_site: none` without Secure or `secure: false` in production makes `bouncer.LoadCookieConfig` return an error naming the key; return it from your plugin's boot so the application does not start with a cookie browsers would drop.
+An invalid domain, `same_site: none` without Secure, or a cookie that is not Secure in production makes `bouncer.LoadCookieConfig` return an error naming the key. In production that covers `secure: false` and an unset `auth.cookie.secure` with an http or missing `app.url`; that error names `auth.cookie.secure` and `app.url`, and you fix it by setting `app.url` to the public https URL or `auth.cookie.secure: true`. Return the error from your plugin's boot so the application does not start with a cookie browsers would drop or send in clear.
 
 `bouncer.CookieConfig.TokenCookie` builds the cookie for a token and a lifetime. Pass the guard's refresh window (`refresh_ttl`, 20160 minutes by default), not its access `ttl`: the access token inside expires after `ttl`, the frontend's 401 handling then calls the refresh endpoint, and that endpoint needs the cookie to still be there. A cookie that died with the token would force a new sign-in every hour. `bouncer.CookieConfig.ForgetTokenCookie` builds the matching cookie that deletes it; it carries the same name, path and domain, or the browser would keep the original.
 
diff --git a/modules/bouncer/README.md b/modules/bouncer/README.md
index b974caa..0e36a48 100644
--- a/modules/bouncer/README.md
+++ b/modules/bouncer/README.md
@@ -31,7 +31,7 @@ Use cases:
 - Context helpers: `bouncer.WithUser` and `bouncer.User` for the principal, `bouncer.WithCredential` and `bouncer.Credential` for the credential behind it (for example an API token record).
 - Scope limits for personal API tokens: `bouncer.ScopeLimit` on `bouncer.Principal.Scope` (nil means unrestricted, as for a JWT session). A token guard sets it after filtering the token's scopes by the request method; `Full` means the token acts as the owner on every method (`*`) or on GET/HEAD (`admin:read`).
 - Blacklist stores behind `bouncer.BlacklistStore`: `bouncer.MemoryBlacklist` for tests and `bouncer.PostgresBlacklist` for production, which works on a caller-supplied table with `jti`, `expires_at` and `valid_until` columns and rejects unsafe table names.
-- Cookie transport: `bouncer.LoadCookieConfig` reads the `auth.cookie.*` block into a `bouncer.CookieConfig` and refuses an invalid domain, `same_site: none` without Secure and `secure: false` in the production environment; `bouncer.CookieConfig.TokenCookie` builds the httpOnly token cookie whose Max-Age is the refresh window, and `bouncer.CookieConfig.ForgetTokenCookie` the matching cookie that deletes it. `bouncer.CookieRefreshHandler` and `bouncer.CookieLogoutHandler` are ready-made handlers for a cookie-based refresh and logout; the application supplies the refresh or revoke call and a writer for its own response envelope.
+- Cookie transport: `bouncer.LoadCookieConfig` reads the `auth.cookie.*` block into a `bouncer.CookieConfig` and refuses an invalid domain, `same_site: none` without Secure and, in the production environment, a Secure that resolves to false (set to `false`, or inferred from an http or unset `app.url`); `bouncer.CookieConfig.TokenCookie` builds the httpOnly token cookie whose Max-Age is the refresh window, and `bouncer.CookieConfig.ForgetTokenCookie` the matching cookie that deletes it. `bouncer.CookieRefreshHandler` and `bouncer.CookieLogoutHandler` are ready-made handlers for a cookie-based refresh and logout; the application supplies the refresh or revoke call and a writer for its own response envelope.
 - Cloudflare Turnstile: `bouncer.Turnstile.Verify` checks a token against siteverify with a 5 second timeout, in PHP's open mode (an empty secret passes) or closed mode (an empty secret is `bouncer.TurnstileUnavailable` in production); `bouncer.Turnstile.Middleware` reads the token from the query, a JSON body or a form body, restores the body and writes refusals through a `bouncer.TurnstileWriter`. surf registers it as `turnstile:open` and `turnstile:closed`.
 - Passwords: `bouncer.HashPassword`, `bouncer.CheckPassword` and `bouncer.NeedsRehash` (bcrypt, cost chosen by the caller).
 
@@ -191,7 +191,7 @@ func RefreshRoute(cfg bouncer.CookieConfigSource, users bouncer.UserProvider, se
 | `auth.cookie.name` | `token` | Cookie name; must be a valid cookie name. |
 | `auth.cookie.domain` | empty (host-only) | Cookie domain. Set a parent domain such as `example.com` to share the cookie between `api.example.com` and `www.example.com`; every subdomain then receives it. An invalid domain fails boot. |
 | `auth.cookie.path` | `/` | Cookie path; must start with `/`. |
-| `auth.cookie.secure` | true when `app.url` is https | Sends the cookie over https only. `false` is refused in the production environment. |
+| `auth.cookie.secure` | true when `app.url` is https | Sends the cookie over https only. In the production environment a value that resolves to false is refused, whether `false` is set or inferred from an http or unset `app.url`. |
 | `auth.cookie.same_site` | `lax` | `lax`, `strict` or `none`; `none` requires Secure. |
 
 Environment variables follow the compass mapping, for example `SUMMER_AUTH__COOKIE__DOMAIN`.
diff --git a/modules/bouncer/cookie.go b/modules/bouncer/cookie.go
index 662f617..a5e1ef2 100644
--- a/modules/bouncer/cookie.go
+++ b/modules/bouncer/cookie.go
@@ -52,8 +52,9 @@ type CookieConfigSource interface {
 //     be a valid cookie domain, so it is never dropped silently when the
 //     cookie is written.
 //   - auth.cookie.same_site: lax (default), strict or none, case-insensitive.
-//   - auth.cookie.secure: unset means true exactly when app.url is https; an
-//     explicit false is refused in the production environment.
+//   - auth.cookie.secure: unset means true exactly when app.url is https. In
+//     the production environment a Secure that resolves to false is refused,
+//     whether set explicitly or inferred from an http or unset app.url.
 //
 // same_site none without Secure is refused, as browsers drop such cookies.
 // Every error names the key.
@@ -101,8 +102,11 @@ func LoadCookieConfig(src CookieConfigSource) (CookieConfig, error) {
 	if err != nil {
 		return cfg, err
 	}
-	if explicit && !secure && strings.EqualFold(strings.TrimSpace(src.Environment()), "production") {
-		return cfg, errors.New("bouncer: auth.cookie.secure: false is not allowed in the production environment")
+	if !secure && strings.EqualFold(strings.TrimSpace(src.Environment()), "production") {
+		if explicit {
+			return cfg, errors.New("bouncer: auth.cookie.secure: false is not allowed in the production environment")
+		}
+		return cfg, errors.New("bouncer: auth.cookie.secure resolves to false in the production environment: it is unset and app.url is not an https URL; set app.url to an https URL or auth.cookie.secure: true")
 	}
 	cfg.Secure = secure
 	if cfg.SameSite == http.SameSiteNoneMode && !cfg.Secure {
diff --git a/modules/bouncer/cookie_test.go b/modules/bouncer/cookie_test.go
index 75e7a1d..f068ef3 100644
--- a/modules/bouncer/cookie_test.go
+++ b/modules/bouncer/cookie_test.go
@@ -39,16 +39,19 @@ func TestLoadCookieConfigDefaults(t *testing.T) {
 		t.Fatalf("nil source = %+v", cfg)
 	}
 
+	// An http or unset app.url infers Secure false outside production only;
+	// production refuses it (TestLoadCookieConfigErrors).
 	for _, tc := range []struct {
 		url    string
+		env    string
 		secure bool
 	}{
-		{"https://app.example.com", true},
-		{"HTTPS://app.example.com", true},
-		{"http://localhost:8000", false},
-		{"", false},
+		{"https://app.example.com", "production", true},
+		{"HTTPS://app.example.com", "production", true},
+		{"http://localhost:8000", "development", false},
+		{"", "development", false},
 	} {
-		cfg, err := LoadCookieConfig(cookieSource{values: map[string]any{"app.url": tc.url}, env: "production"})
+		cfg, err := LoadCookieConfig(cookieSource{values: map[string]any{"app.url": tc.url}, env: tc.env})
 		if err != nil {
 			t.Fatalf("app.url %q: %v", tc.url, err)
 		}
@@ -104,6 +107,8 @@ func TestLoadCookieConfigErrors(t *testing.T) {
 		{"same_site none on http app", map[string]any{"auth.cookie.same_site": "none", "app.url": "http://localhost"}, "", "auth.cookie.same_site"},
 		{"secure false in production", map[string]any{"auth.cookie.secure": false}, "production", "auth.cookie.secure"},
 		{"secure string false in production", map[string]any{"auth.cookie.secure": "false"}, "Production", "auth.cookie.secure"},
+		{"secure inferred from http app.url in production", map[string]any{"app.url": "http://api.example.com"}, "production", "app.url"},
+		{"secure inferred from unset app.url in production", map[string]any{}, "production", "auth.cookie.secure resolves to false"},
 		{"secure not a bool", map[string]any{"auth.cookie.secure": "maybe"}, "", "auth.cookie.secure"},
 		{"secure wrong type", map[string]any{"auth.cookie.secure": 1}, "", "auth.cookie.secure"},
 		{"unknown same_site", map[string]any{"auth.cookie.same_site": "relaxed"}, "", "auth.cookie.same_site"},