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

The empty-TRUSTED_PROXIES warning was gated on IsProd(), but
WEBHOOKER_ENVIRONMENT defaults to dev, so an internet-exposed
deployment whose operator never set it got no warning at all — the
exact operator error the warning exists to catch. It now fires whenever
the list is empty, in any environment, and its text is accurate both
behind a reverse proxy (shared buckets, remotely deniable admin login)
and with nothing in front of the process (harmless). The startup
configuration summary also now logs sessionIdleTimeout, the one value
where a valid setting silently disables a security control.

The README documented a two-stage Docker build on golang:1.24 running
"make check" (the tree has three stages: a golangci-lint lint stage
running fmt-check and lint, a golang:1.26.1-bookworm builder running
test and build, then the Alpine runtime), advertised the public
receiver as accepting all methods (it answers 405 to everything but
POST), claimed unqualified per-IP login rate limiting, and left the
session-expiry prose orphaned inside the trusted-proxy subsection.

The rest of the README was swept against the code rather than only the
reported lines: every documented route checked method-by-method against
internal/server/routes.go (adding the password-change, entrypoint and
target routes that were missing), every environment variable checked
against internal/config/config.go (MAINTENANCE_MODE serves no
maintenance page — it only sets a healthcheck field), the fx wiring,
package tree, prerequisites and dev commands brought back in line with
the tree, and two statements known false from other reviews corrected:
the body-size limit does not reject before "any other middleware" (the
eight global ones run first), and a retention value at or above the
retain-forever sentinel is accepted rather than 400ed.

TODO.md drops the unsupported half of its CI claim, keeping the
cache-defeated container runs, and splits the landed password change
away from the unimplemented reset flow.

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",
+			)
 		})
 	}
 }