Default WEBHOOKER_ENVIRONMENT to prod

An unset WEBHOOKER_ENVIRONMENT now resolves to prod rather than dev, so
an operator who forgets the variable is not silently permissive. The
only behaviour dev still changes is the CORS middleware, which answers
every origin with Access-Control-Allow-Origin: *; that is now off
unless dev is set explicitly. Cookie Secure and CSRF strictness are
decided per request from the transport and are unaffected.

Updated resolveEnvironment and its comment, the README configuration
table and prose, and tests covering the default and the explicit dev.
Comments that justified behaviour by the old dev default (the
TRUSTED_PROXIES warning, a CSRF test) were corrected; that warning
still fires in every environment when TRUSTED_PROXIES is empty.

Model: opus-4-8

README.md

@@ -92,7 +92,8 @@ them at once. A variable already present in the real environment wins
 over the file's value for the same name.
 
 The environment is selected by setting `WEBHOOKER_ENVIRONMENT` to `dev`
-or `prod` (default: `dev`). The setting controls exactly one behavior:
+or `prod` (default: `prod`; `dev` must be set explicitly). The setting
+controls exactly one behavior:
 
 | Behavior | `dev`                   | `prod`           |
 | -------- | ----------------------- | ---------------- |
@@ -134,7 +135,7 @@ TTY detection, and security headers are always applied.
 
 | Variable                | Description                         | Default  |
 | ----------------------- | ----------------------------------- | -------- |
-| `WEBHOOKER_ENVIRONMENT` | `dev` or `prod`                     | `dev`    |
+| `WEBHOOKER_ENVIRONMENT` | `dev` or `prod`                     | `prod`   |
 | `PORT`                  | HTTP listen port                    | `8080`   |
 | `BIND_ADDRESS`          | IP address the HTTP listener binds. Loopback by default, so the cleartext listener is not published on every interface. The Docker image ships `0.0.0.0` instead. See [Bind address](#bind-address) | `127.0.0.1` (image: `0.0.0.0`) |
 | `DATA_DIR`              | Directory for all SQLite databases  | `/var/lib/webhooker` |
@@ -400,9 +401,9 @@ the bucket is. See [Rate Limiting](#rate-limiting).
 The remedy is to set `TRUSTED_PROXIES` to your reverse proxy's
 address, which restores per-client buckets. webhooker logs a warning
 at startup whenever `TRUSTED_PROXIES` is empty, in every environment —
-not only when `WEBHOOKER_ENVIRONMENT=prod`, because that variable
-defaults to `dev` and an operator who never set it is precisely the
-one at risk. The warning is informational when nothing proxies to the
+the warning does not depend on `WEBHOOKER_ENVIRONMENT`, because an
+operator who never configured the deployment is precisely the one at
+risk. The warning is informational when nothing proxies to the
 process: with no proxy in front, the peer address is the client's own
 and the buckets are already per-client. See
 [Rate Limiting](#rate-limiting) for what each limit shares.
@@ -754,15 +755,15 @@ reports.
    that.
 2. **Set `WEBHOOKER_ENVIRONMENT=prod`, and make sure the proxy sends
    `X-Forwarded-Proto`.** These are two requirements, not one. The
-   environment setting decides CORS and nothing else: the default
-   `dev` answers every origin with `Access-Control-Allow-Origin: *`
-   (without credentials), which a server-rendered production
-   deployment has no use for. Cookie `Secure` and the strict
-   Origin/Referer mode are **not** tied to it — they are decided per
-   request from the transport, which behind a proxy means the
-   `X-Forwarded-Proto` header. The block below sets it; without it
-   every request is read as plaintext and cookies ship without
-   `Secure`. See [Configuration](#configuration).
+   environment setting decides CORS and nothing else: `dev` answers
+   every origin with `Access-Control-Allow-Origin: *` (without
+   credentials), which a server-rendered production deployment has no
+   use for, and `prod` — the default — disables it. Cookie `Secure`
+   and the strict Origin/Referer mode are **not** tied to it — they
+   are decided per request from the transport, which behind a proxy
+   means the `X-Forwarded-Proto` header. The block below sets it;
+   without it every request is read as plaintext and cookies ship
+   without `Secure`. See [Configuration](#configuration).
 3. **Set `TRUSTED_PROXIES` to the proxy's address.** Unset, every rate
    limiter keys on the connecting peer, which behind a proxy is the
    proxy on every request: all clients collapse into one global bucket

internal/config/config.go

@@ -585,12 +585,14 @@ func resolveMetricsAuth() (string, string, error) {
 	)
 }
 
-// resolveEnvironment reads WEBHOOKER_ENVIRONMENT, defaulting to
-// dev, and rejects unrecognised values.
+// resolveEnvironment reads WEBHOOKER_ENVIRONMENT, defaulting to prod
+// when it is unset so a deployment that forgets the variable is not
+// silently permissive; dev must be set explicitly. It rejects
+// unrecognised values.
 func resolveEnvironment() (string, error) {
 	environment := os.Getenv("WEBHOOKER_ENVIRONMENT")
 	if environment == "" {
-		environment = EnvironmentDev
+		environment = EnvironmentProd
 	}
 
 	if environment != EnvironmentDev &&
@@ -772,10 +774,10 @@ func (c *Config) warnEgressAllowlist(log *slog.Logger) {
 // everyone else's wrong passwords, and the receiver's limits become
 // service-wide ceilings.
 //
-// The warning is deliberately not gated on WEBHOOKER_ENVIRONMENT. That
-// variable defaults to dev, so gating on it would silence the warning
-// for exactly the operator who forgot to configure the deployment —
-// the case it exists to catch.
+// The warning is deliberately not gated on WEBHOOKER_ENVIRONMENT: an
+// operator who never configured the deployment is exactly the case it
+// exists to catch, so the exposure it announces is independent of the
+// environment setting.
 //
 // The default of trusting nobody is deliberate — trusting forwarded
 // headers from arbitrary peers lets any client choose its own bucket —

internal/config/config_test.go

@@ -44,9 +44,9 @@ func TestEnvironmentConfig(t *testing.T) {
 		isProd      bool
 	}{
 		{
-			name:   "default is dev",
-			isDev:  true,
-			isProd: false,
+			name:   "default is prod",
+			isDev:  false,
+			isProd: true,
 		},
 		{
 			name:     "explicit dev",
@@ -848,10 +848,10 @@ func TestEgressAllowlistWarning(t *testing.T) {
 // tells an operator a deployment behind a reverse proxy shares one
 // rate-limit bucket between every client, which turns the receiver
 // limits into service-wide ceilings and collapses login failure
-// counting. It must fire whenever TRUSTED_PROXIES is empty,
-// in any environment: WEBHOOKER_ENVIRONMENT defaults to dev, so gating
-// on it would silence the warning for exactly the operator who never
-// configured the deployment. It stays quiet once proxies are named.
+// counting. It must fire whenever TRUSTED_PROXIES is empty, in any
+// environment: the warning does not depend on WEBHOOKER_ENVIRONMENT,
+// since an operator who never configured the deployment is exactly the
+// one it exists to catch. It stays quiet once proxies are named.
 func TestSharedRateLimitBucketWarning(t *testing.T) {
 	tests := []struct {
 		name           string
@@ -871,10 +871,9 @@ func TestSharedRateLimitBucketWarning(t *testing.T) {
 			expectWarning:  false,
 		},
 		{
-			// The default environment. An internet-exposed
-			// deployment whose operator never set
-			// WEBHOOKER_ENVIRONMENT lands here and has exactly
-			// the exposure the warning announces.
+			// An internet-exposed deployment whose operator set
+			// WEBHOOKER_ENVIRONMENT=dev has exactly the exposure
+			// the warning announces.
 			name:          "dev without trusted proxies warns",
 			environment:   config.EnvironmentDev,
 			expectWarning: true,

internal/middleware/csrf_test.go

@@ -380,9 +380,8 @@ func csrfTookStrictPath(
 
 // TestCSRF_ForwardedProtoSpellingsTakeStrictPath runs the header
 // spellings a real proxy emits through the middleware. The environment
-// is dev -- the DEFAULT when WEBHOOKER_ENVIRONMENT is unset -- to pin
-// that the routing is a per-request transport decision and owes
-// nothing to configuration.
+// is set to dev -- the permissive setting -- to pin that the routing is
+// a per-request transport decision and owes nothing to configuration.
 func TestCSRF_ForwardedProtoSpellingsTakeStrictPath(t *testing.T) {
 	t.Parallel()