diff --git a/README.md b/README.md
index 35d8737..a89c725 100644
--- a/README.md
+++ b/README.md
@@ -138,7 +138,7 @@ Environment variables consumed by `internal/config/config.go`:
 | `BASE_URL` | _empty_ | Overrides the constructed `baseUrl` if set (used for HTTPS perimeter). |
 | `REDIS_PORT` | `6379` | Local Redis port. |
 | `META_CORE_HTTP_PORT` | `9000` | Go HTTP+SSE+WebDAV port. |
-| `META_CORE_HTTP_HOST` | `127.0.0.1` | HTTP bind. |
+| `META_CORE_HTTP_HOST` | `0.0.0.0` | HTTP bind. |
 | `HEALTH_CHECK_INTERVAL_MS` | `5000` | Internal health-loop cadence. |
 | `HEARTBEAT_INTERVAL_MS` | `30000` | Service registry heartbeat. |
 | `STALE_THRESHOLD_MS` | `60000` | Age past which a registry entry is marked stale. |
diff --git a/docs/meta-core-architecture.md b/docs/meta-core-architecture.md
index 97912b3..db4afcd 100644
--- a/docs/meta-core-architecture.md
+++ b/docs/meta-core-architecture.md
@@ -515,7 +515,7 @@ via `/health`; metadata I/O and SSE event streams stop.
 | `BASE_URL` | _empty_ | Overrides constructed `baseUrl` (HTTPS perimeter). |
 | `REDIS_PORT` | `6379` | Local Redis port. |
 | `META_CORE_HTTP_PORT` | `9000` | Go HTTP+SSE+WebDAV port. |
-| `META_CORE_HTTP_HOST` | `127.0.0.1` | HTTP bind address. |
+| `META_CORE_HTTP_HOST` | `0.0.0.0` | HTTP bind address. |
 | `HEALTH_CHECK_INTERVAL_MS` | `5000` | Internal health-loop cadence. |
 | `HEARTBEAT_INTERVAL_MS` | `30000` | Service registry heartbeat. |
 | `STALE_THRESHOLD_MS` | `60000` | Age past which a registry entry is stale. |
diff --git a/internal/config/config.go b/internal/config/config.go
index 4606229..f2873c9 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -24,7 +24,7 @@ type Config struct {
 
 	// HTTP API configuration
 	HTTPPort int    // HTTP API port (default: 9000)
-	HTTPHost string // HTTP API host (default: "127.0.0.1")
+	HTTPHost string // HTTP API host (default: "0.0.0.0" — meta-core always runs in a container and must answer siblings)
 
 	// Timing configuration
 	HealthCheckIntervalMS    int // Health check interval in ms (default: 5000)
@@ -54,7 +54,7 @@ func Load() *Config {
 		PublicURL:             getEnv("META_CORE_PUBLIC_URL", ""),
 		RedisPort:             getEnvInt("REDIS_PORT", 6379),
 		HTTPPort:              getEnvInt("META_CORE_HTTP_PORT", 9000),
-		HTTPHost:              getEnv("META_CORE_HTTP_HOST", "127.0.0.1"),
+		HTTPHost:              getEnv("META_CORE_HTTP_HOST", "0.0.0.0"),
 		HealthCheckIntervalMS:  getEnvInt("HEALTH_CHECK_INTERVAL_MS", 5000),
 		HeartbeatIntervalMS:   getEnvInt("HEARTBEAT_INTERVAL_MS", 30000),
 		StaleThresholdMS:      getEnvInt("STALE_THRESHOLD_MS", 60000),