docs: document binary builds

.gitignore

@@ -5,3 +5,5 @@ config.yaml
 docker-compose.yml
 notes.md
 roadmap.md
+
+binaries/

CONTRIBUTING.md

@@ -293,6 +293,14 @@ git push origin main --tags
 ```
 
 7. Publish release notes on GitHub against the new tag
+8. Build release binaries and attach them to the GitHub release:
+
+```bash
+./build-release.sh
+```
+
+The script reads the version from the git tag automatically. Upload the
+resulting files from `binaries/` as release assets on GitHub.
 
 ## Recognition
 

build-release.sh

@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+# Copyright 2026 Beacon Contributors
+# SPDX-License-Identifier: AGPL-3.0-or-later
+#
+# build-release.sh — cross-compile Beacon for all supported platforms.
+# Output binaries are written to ./binaries/.
+
+set -euo pipefail
+
+PACKAGE="./cmd/beacon"
+OUTPUT_DIR="binaries"
+VERSION=$(git describe --tags --always --dirty 2>/dev/null || echo "dev")
+
+mkdir -p "$OUTPUT_DIR"
+
+targets=(
+    "linux/amd64/"
+    "linux/arm64/"
+    "linux/arm/7"
+    "darwin/amd64/"
+    "darwin/arm64/"
+    "windows/amd64/"
+)
+
+echo "Building Beacon $VERSION"
+
+for target in "${targets[@]}"; do
+    GOOS=$(echo "$target" | cut -d/ -f1)
+    GOARCH=$(echo "$target" | cut -d/ -f2)
+    GOARM=$(echo "$target" | cut -d/ -f3)
+
+    NAME="beacon-${VERSION}-${GOOS}-${GOARCH}"
+    if [[ -n "$GOARM" ]]; then
+        NAME="${NAME}v${GOARM}"
+    fi
+
+    if [[ "$GOOS" == "windows" ]]; then
+        NAME="${NAME}.exe"
+    fi
+
+    printf "  %-40s" "${GOOS}/${GOARCH}${GOARM:+v$GOARM}"
+
+    env GOOS="$GOOS" GOARCH="$GOARCH" ${GOARM:+GOARM="$GOARM"} \
+        go build -trimpath -ldflags="-s -w -X main.version=${VERSION}" \
+        -o "${OUTPUT_DIR}/${NAME}" "$PACKAGE"
+
+    echo "→ ${OUTPUT_DIR}/${NAME}"
+done
+
+echo "Done."

cmd/beacon/main.go

@@ -33,6 +33,10 @@ import (
 	"github.com/joho/godotenv"
 )
 
+// version is set at build time via -ldflags "-X main.version=vX.Y.Z".
+// Falls back to "dev" when built without the flag.
+var version = "dev"
+
 //	@title			MeshCore Beacon API
 //	@version		1.4.0
 //	@description	MeshCore network observation backend. Ingests LoRa packets from MQTT brokers, stores in PostgreSQL, and streams live events via WebSocket.
@@ -67,6 +71,7 @@ import (
 // @tag.name			Stats
 // @tag.description	Network statistics and time series
 func main() {
+	log.Printf("beacon version %s", version)
 	_ = godotenv.Load()
 	addr := os.Getenv("LISTEN_ADDR")
 	if addr == "" {