fix: allow --gc-max-idle 0 for immediate pruning

Validation rejected 0 despite the v1.8.1 changelog documenting it as
valid ("prune immediately"). Changed check from <= 0 to < 0 and updated
tests accordingly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mtingers

CHANGELOG.md

@@ -5,6 +5,14 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [v1.13.2] - 2026-03-07
+
+### Fixed
+
+- **Config: `--gc-max-idle 0` rejected despite being documented as valid** — validation used `<= 0` instead of `< 0`, preventing the "prune immediately" setting documented in the v1.8.1 changelog from being configured via CLI or environment variable
+
+[v1.13.2]: https://github.com/mtingers/dflockd/releases/tag/v1.13.2
+
 ## [v1.13.1] - 2026-03-07
 
 ### Fixed

internal/config/config.go

@@ -237,8 +237,8 @@ func (c *Config) validate() error {
 	if c.MaxSubscriptions < 0 {
 		return fmt.Errorf("--max-subscriptions must be >= 0 (got %d)", c.MaxSubscriptions)
 	}
-	if c.GCMaxIdleTime <= 0 {
-		return fmt.Errorf("--gc-max-idle must be > 0 (got %s)", c.GCMaxIdleTime)
+	if c.GCMaxIdleTime < 0 {
+		return fmt.Errorf("--gc-max-idle must be >= 0 (got %s)", c.GCMaxIdleTime)
 	}
 	if (c.TLSCert != "") != (c.TLSKey != "") {
 		return fmt.Errorf("both --tls-cert and --tls-key must be provided together")

internal/config/config_test.go

@@ -36,7 +36,7 @@ func TestLoad_ValidationErrors(t *testing.T) {
 		{"default-lease-ttl=0", []string{"--default-lease-ttl", "0"}, "default-lease-ttl"},
 		{"lease-sweep-interval=0", []string{"--lease-sweep-interval", "0"}, "lease-sweep-interval"},
 		{"gc-interval=0", []string{"--gc-interval", "0"}, "gc-interval"},
-		{"gc-max-idle=0", []string{"--gc-max-idle", "0"}, "gc-max-idle"},
+		{"gc-max-idle=-1", []string{"--gc-max-idle", "-1"}, "gc-max-idle"},
 		{"read-timeout=0", []string{"--read-timeout", "0"}, "read-timeout"},
 		{"port negative", []string{"--port", "-1"}, "port"},
 		{"port too high", []string{"--port", "99999"}, "port"},
@@ -81,6 +81,12 @@ func TestLoad_ValidEdgeCases(t *testing.T) {
 	if err != nil {
 		t.Fatalf("max-waiters=0 should be valid: %v", err)
 	}
+
+	// gc-max-idle=0 is valid (prune immediately)
+	_, err = Load([]string{"--gc-max-idle", "0"})
+	if err != nil {
+		t.Fatalf("gc-max-idle=0 should be valid: %v", err)
+	}
 }
 
 func TestSecondsCeil(t *testing.T) {