Correct release-blocking README and startup-warning inaccuracies (closes #151)

Publishing this README would have shipped false statements about the
product. Corrects the eight items on the issue plus everything a full
sweep turned up: the Slack circuit-breaker scope, a nonexistent WAL, the
wrong config key for slack targets, six undocumented routes, the
conditional /metrics registration, wrong retention bands, wrong shutdown
mechanism, and a Quick Start that led a new contributor into a red
build.

The lockout warning now fires whenever TRUSTED_PROXIES is empty rather
than only in production, since the variable it was gated on defaults to
dev. Rate-limit keying, the limits and the TRUSTED_PROXIES default are
untouched — those belong to #150.

What /s/* actually serves was settled empirically rather than by
reading: all five of GET/HEAD/POST/PUT/DELETE return 200, pinned by
TestStaticServesEveryMethod. Restricting it is filed separately.

Independently reviewed after three prior rounds. The reviewer
re-derived all fifteen claim-table rows against the code, including
every row a previous revision had marked "correct, left alone" and got
wrong, and found zero false; then verified every route method-by-method,
all twelve environment variables, all nine entity tables, and the
package tree against git ls-files. The Quick Start was confirmed by
running it in a fresh clone.

internal/config/config.go

@@ -422,33 +422,43 @@ func loadFromEnv() (*Config, error) {
 	}, nil
 }
 
-// warnSharedRateLimitBucket logs a startup warning when a production
-// deployment leaves TRUSTED_PROXIES empty.
+// warnSharedRateLimitBucket logs a startup warning whenever
+// TRUSTED_PROXIES is empty, in any environment.
 //
 // With no trusted proxies every rate limiter keys on the connecting
-// peer's address. A production deployment is required to run behind a
-// TLS-terminating reverse proxy, and the peer is then that proxy for
-// every request, so all clients share one bucket per limiter. The
+// peer's address. Whether that is harmless or dangerous depends on
+// what is in front of the process, which this code cannot observe:
+// with nothing in front, the peer is the client and the limits are
+// per-client as intended; behind a reverse proxy the peer is the proxy
+// for every request, so all clients share one bucket per limiter. The
 // login limiter's bucket is the dangerous one: any remote client can
-// keep it full, which denies the only administrative login to
-// everyone until the process restarts.
+// keep it full, which denies the only administrative login to everyone
+// until the process restarts.
+//
+// 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 default of trusting nobody is deliberate — trusting forwarded
 // headers from arbitrary peers lets any client choose its own bucket —
 // so this warns rather than failing startup or changing the key.
 func (c *Config) warnSharedRateLimitBucket(log *slog.Logger) {
-	if !c.IsProd() || len(c.TrustedProxies) > 0 {
+	if len(c.TrustedProxies) > 0 {
 		return
 	}
 
 	log.Warn(
-		"TRUSTED_PROXIES is empty: rate limits key on the "+
-			"connecting peer, so behind the reverse proxy a "+
-			"production deployment runs behind, every client "+
-			"shares one bucket per limit. Any remote client can "+
-			"then keep the login limit full and deny the admin "+
-			"login, the only administrative path, until restart. "+
-			"Set TRUSTED_PROXIES to your reverse proxy's address.",
+		"TRUSTED_PROXIES is empty: every rate limit keys on the "+
+			"connecting peer's address. With nothing proxying to "+
+			"this process that is the client itself and the limits "+
+			"are per-client as intended. Behind a reverse proxy the "+
+			"peer is the proxy on every request, so all clients "+
+			"share one bucket per limit and any remote client can "+
+			"keep the login limit full, denying the admin login — "+
+			"the only administrative path — until restart. If "+
+			"anything proxies to this process, set TRUSTED_PROXIES "+
+			"to its address.",
 		"environment", c.Environment,
 		"trustedProxies", len(c.TrustedProxies),
 	)
@@ -491,6 +501,10 @@ func New(lc fx.Lifecycle, params ConfigParams) (*Config, error) {
 		"maintenanceMode", s.MaintenanceMode,
 		"dataDir", s.DataDir,
 		"retentionSweepInterval", s.RetentionSweepInterval.String(),
+		// Logged because a perfectly valid non-positive value here
+		// disables idle expiry entirely, and that is worth showing
+		// back to the operator.
+		"sessionIdleTimeout", s.SessionIdleTimeout.String(),
 		"receiverRateLimit", s.ReceiverRateLimit,
 		"trustedProxies", len(s.TrustedProxies),
 		"hasSentryDSN", s.SentryDSN != "",

internal/config/config_test.go

@@ -628,10 +628,12 @@ func testTrustedProxiesSuccess(
 }
 
 // TestSharedRateLimitBucketWarning covers the startup warning that
-// tells an operator their production deployment shares one rate-limit
-// bucket between every client, which makes the admin login remotely
-// deniable. It must fire when TRUSTED_PROXIES is empty in production
-// and stay quiet otherwise.
+// tells an operator a deployment behind a reverse proxy shares one
+// rate-limit bucket between every client, which makes the admin login
+// remotely deniable. 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.
 func TestSharedRateLimitBucketWarning(t *testing.T) {
 	tests := []struct {
 		name           string
@@ -651,12 +653,19 @@ func TestSharedRateLimitBucketWarning(t *testing.T) {
 			expectWarning:  false,
 		},
 		{
-			// Development is not required to run behind a
-			// reverse proxy, so the shared bucket the warning
-			// describes is not the expected shape there.
-			name:          "dev without trusted proxies is quiet",
+			// The default environment. An internet-exposed
+			// deployment whose operator never set
+			// WEBHOOKER_ENVIRONMENT lands here and has exactly
+			// the exposure the warning announces.
+			name:          "dev without trusted proxies warns",
 			environment:   config.EnvironmentDev,
-			expectWarning: false,
+			expectWarning: true,
+		},
+		{
+			name:           "dev with trusted proxies is quiet",
+			environment:    config.EnvironmentDev,
+			trustedProxies: cidrPrivateV4,
+			expectWarning:  false,
 		},
 	}
 
@@ -697,8 +706,14 @@ func TestSharedRateLimitBucketWarning(t *testing.T) {
 
 			assert.Contains(t, logged, `"level":"WARN"`)
 			assert.Contains(t, logged, "TRUSTED_PROXIES")
-			assert.Contains(t, logged, "shares one bucket")
-			assert.Contains(t, logged, "deny the admin login")
+			assert.Contains(t, logged, "share one bucket")
+			assert.Contains(t, logged, "denying the admin login")
+			// The text must stay accurate for a developer with
+			// nothing in front of the process, where an empty
+			// list costs nothing.
+			assert.Contains(
+				t, logged, "nothing proxying to this process",
+			)
 		})
 	}
 }

internal/server/routes_test.go

@@ -24,6 +24,7 @@ import (
 	"sneak.berlin/go/webhooker/internal/middleware"
 	"sneak.berlin/go/webhooker/internal/server"
 	"sneak.berlin/go/webhooker/internal/session"
+	"sneak.berlin/go/webhooker/static"
 )
 
 // csrfCookieName is the cookie gorilla/csrf issues when it runs. Its
@@ -246,6 +247,56 @@ func (e *testEnv) storedHash(t *testing.T, username string) string {
 	return user.Password
 }
 
+// --- /s static group ---
+
+// TestStaticServesEveryMethod pins what the static mount actually
+// answers. chi's Mount registers the handler for all methods and
+// http.FileServer only special-cases HEAD (by suppressing the body),
+// so a POST or a DELETE to an asset is served the file rather than
+// refused. The README documents this; the test is what keeps the two
+// from drifting.
+func TestStaticServesEveryMethod(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnv(t)
+
+	body, err := static.Static.ReadFile("js/app.js")
+	require.NoError(t, err)
+	require.NotEmpty(t, body)
+
+	for _, method := range []string{
+		http.MethodGet,
+		http.MethodHead,
+		http.MethodPost,
+		http.MethodPut,
+		http.MethodDelete,
+	} {
+		t.Run(method, func(t *testing.T) {
+			t.Parallel()
+
+			req := httptest.NewRequestWithContext(
+				context.Background(), method,
+				"/s/js/app.js", nil,
+			)
+			w := httptest.NewRecorder()
+			env.router.ServeHTTP(w, req)
+
+			assert.Equal(t, http.StatusOK, w.Code,
+				"static mount answers every method")
+
+			if method == http.MethodHead {
+				assert.Empty(t, w.Body.Bytes(),
+					"HEAD must not carry a body")
+
+				return
+			}
+
+			assert.Equal(t, body, w.Body.Bytes(),
+				"the asset itself is returned")
+		})
+	}
+}
+
 // --- /pages group ---
 
 // TestPagesLogin_OversizeBody_RejectedBeforeCSRF proves the cap runs