ai-dev: graceful shutdown, tests, stdlib context, lint/CI, error logging

- T1: SIGTERM/SIGINT → client.Disconnect(250) → os.Exit(0)
- T2: 11 tests with miniredis mock (handleMessage, getEnv, parseInt, randomString)
- T3: golang.org/x/net/context → stdlib context, math/rand → math/rand/v2
- T4: .golangci.yml + .github/workflows/ci.yml
- T5: Redis SETEX error log includes key and memberID
- Dockerfile: add git for go mod tidy

.github/workflows/ci.yml

@@ -0,0 +1,38 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "1.24"
+      - uses: golangci/golangci-lint-action@v6
+        with:
+          working-directory: mqtt_presence_redis_go
+
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "1.24"
+      - run: go test ./...
+        working-directory: mqtt_presence_redis_go
+
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "1.24"
+      - run: go build ./...
+        working-directory: mqtt_presence_redis_go

AGENTS.md

@@ -0,0 +1,117 @@
+# Repository Guidelines
+
+## Project Overview
+
+MQTT presence service written in Go. Subscribes to an MQTT topic (`presence`), parses incoming messages (`memberID;...`), and stores presence data in Redis with a TTL. Purpose: real-time member presence tracking for the Backone platform (port of a Django/Python original).
+
+## Architecture & Data Flow
+
+```
+MQTT Broker ──publish──▶ MQTT Client (paho.mqtt)
+                              │
+                              ▼
+                        handleMessage()
+                        - parse memberID from payload (split on ";")
+                        - truncate memberID to 50 chars
+                        - build JSON {mqtt, ts}
+                        - SETEX to Redis key "presence:<memberID>"
+                              │
+                              ▼
+                           Redis
+```
+
+Single goroutine architecture. `main()` connects Redis, connects MQTT, subscribes on connect, then blocks forever (`select {}`). All message handling is synchronous in the MQTT callback.
+
+## Key Directories
+
+```
+backone-manage-go/
+├── mqtt_presence_redis_go/     # ALL source code lives here
+│   ├── mqtt_presence_redis_go.go  # Single-file application (package main)
+│   ├── go.mod / go.sum
+│   └── Dockerfile
+├── .gitignore
+└── README.md
+```
+
+No subpackages, no internal/, no cmd/. The entire application is one `.go` file.
+
+## Development Commands
+
+```bash
+# Build
+cd mqtt_presence_redis_go && go build -o mqtt_presence_redis_go mqtt_presence_redis_go.go
+
+# Run locally (requires MQTT broker + Redis running)
+cd mqtt_presence_redis_go && go run mqtt_presence_redis_go.go
+
+# Docker build
+cd mqtt_presence_redis_go && docker build -t mqtt-presence-redis-go .
+
+# No Makefile, no CI pipeline, no lint config
+```
+
+## Code Conventions & Common Patterns
+
+### Configuration
+- **All config via environment variables** — no config files, no viper/yaml.
+- Pattern: `getEnv("ENV_KEY", "default")` helper at package level.
+- Env vars: `MQTT_HOST`, `MQTT_PORT`, `MQTT_USER`, `MQTT_PASS`, `MQTT_TOPIC_PRESENCE`, `MQTT_REDIS_HOST`, `MQTT_REDIS_PORT`, `MQTT_REDIS_DB`, `MQTT_REDIS_PREFIX`, `MQTT_REDIS_SETEX`, `MQTT_REDIS_PASSWORD`.
+
+### Naming
+- Package-level vars: `camelCase` (e.g. `mqttHost`, `redisPrefix`).
+- Functions: `camelCase` (e.g. `handleMessage`, `getEnv`, `parseInt`, `randomString`).
+- Constants: no `const` block used; inline defaults.
+- File naming: `<package_name>.go` matches module directory.
+
+### Error Handling
+- `log.Fatalf` for startup failures (Redis ping, MQTT connect).
+- `log.Printf` + `return` for runtime errors (message handling).
+- No custom error types; no error wrapping.
+
+### Dependencies
+- `github.com/eclipse/paho.mqtt.golang` — MQTT client
+- `github.com/go-redis/redis/v8` — Redis client
+- `golang.org/x/net/context` — context (stdlib `context` preferred in Go 1.7+)
+
+### Patterns
+- No interfaces, no DI, no dependency injection.
+- No middleware, no routing — single topic subscription.
+- No graceful shutdown handling (`select {}` blocks forever).
+- `math/rand` for client ID (not `crypto/rand`) — acceptable for non-security use.
+- JSON marshaling via `map[string]interface{}` — no typed struct for presence data.
+
+## Important Files
+
+| File | Purpose |
+|------|---------|
+| `mqtt_presence_redis_go/mqtt_presence_redis_go.go` | Entire application |
+| `mqtt_presence_redis_go/go.mod` | Module: `git.proit.id/dsutanto/backone-manage-go/mqtt_presence_redis_go`, Go 1.24.3 |
+| `mqtt_presence_redis_go/Dockerfile` | Multi-stage build: `golang:1.24-alpine` → `alpine:3.20` |
+
+## Runtime/Tooling Preferences
+
+- **Go 1.24.3** (specified in go.mod and Dockerfile)
+- **No package manager** beyond `go mod`
+- **No linter configured** (no `.golangci.yml`)
+- **No formatter config** (standard `gofmt` assumed)
+- **No CI/CD** — deployment via Docker only
+- **Redis 8 client** (`go-redis/v8`) — requires Redis 6+ for SETEX
+- **MQTT 3.1.1** via paho client
+
+## Testing & QA
+
+- **No tests exist.** No `*_test.go` files anywhere.
+- **No test framework configured.**
+- No coverage tooling, no test scripts.
+- If adding tests: use standard `testing` package. Table-driven tests for `handleMessage` message parsing logic. Mock Redis with `miniredis` or `go-redis/mock`. Mock MQTT with a test broker or interface-based mock.
+
+## Key Observations for AI Assistants
+
+1. **Single-file architecture** — all changes go in `mqtt_presence_redis_go.go`. No cross-file imports to track.
+2. **No tests** — any refactor carries risk. Consider adding tests for `handleMessage` before significant changes.
+3. **No graceful shutdown** — `select {}` means no signal handling, no MQTT disconnect on SIGTERM. Docker sends SIGTERM then SIGKILL.
+4. **`golang.org/x/net/context`** is used instead of stdlib `context` — this is a legacy import; stdlib `context` is standard since Go 1.7.
+5. **Payload parsing** is fragile: splits on `;`, takes first element, truncates to 50 chars. No validation of payload format.
+6. **Redis key pattern**: `presence:<memberID>` with configurable prefix and TTL (default 86400s / 24h).
+7. **The comment about Django** indicates this is a port — check Python original for behavioral reference if behavior questions arise.

SPEC.md

@@ -0,0 +1,56 @@
+# SPEC.md — MQTT Presence Redis Go
+
+## §G Goal
+
+MQTT presence bridge: subscribe MQTT topic, parse memberID, store presence JSON in Redis with TTL. Port of Django original for Backone platform.
+
+## §C Constraints
+
+- Single binary, single file (`mqtt_presence_redis_go.go`)
+- Go 1.24.3
+- All config via env vars, no config files
+- Redis 6+ required (SETEX)
+- MQTT 3.1.1 via paho client
+- Docker deployment (multi-stage: golang:1.24-alpine → alpine:3.20)
+- No graceful shutdown — blocks forever (`select {}`)
+- No tests, no CI, no linter
+
+## §I Interfaces
+
+| id | type | detail |
+|----|------|--------|
+| I.mqtt | input | Subscribe `MQTT_TOPIC_PRESENCE` (default `presence`), QoS 0, KeepAlive 30s, CleanSession true, AutoReconnect true (paho defaults) |
+| I.redis | output | `SETEX presence:<memberID>` with JSON `{mqtt, ts}`, TTL `MQTT_REDIS_SETEX` seconds |
+| I.env | config | `MQTT_HOST`, `MQTT_PORT`, `MQTT_USER`, `MQTT_PASS`, `MQTT_TOPIC_PRESENCE`, `MQTT_REDIS_HOST`, `MQTT_REDIS_PORT`, `MQTT_REDIS_DB`, `MQTT_REDIS_PREFIX`, `MQTT_REDIS_SETEX`, `MQTT_REDIS_PASSWORD` |
+
+## §V Invariants
+
+| id | invariant |
+|----|-----------|
+| V1 | memberID extracted as first `;`-delimited segment of MQTT payload |
+| V2 | memberID truncated to 50 chars max |
+| V3 | Redis key format: `<MQTT_REDIS_PREFIX>:<memberID>` (default `presence:<memberID>`) |
+| V4 | Redis value: JSON `{mqtt: <raw_payload>, ts: <unix_timestamp>}` |
+| V5 | Redis TTL: `MQTT_REDIS_SETEX` seconds (default 86400 = 24h) |
+| V6 | MQTT client ID: `mqtt_presence_redis_go_<random10>` — random per restart |
+| V7 | Startup fails fast (`log.Fatalf`) if Redis ping or MQTT connect fails |
+| V8 | On MQTT connect/reconnect: auto-subscribe to presence topic |
+| V9 | Empty payload → `memberID = ""` → Redis key `presence:` → write still occurs (current behavior, not early-return) |
+| V10 | Each MQTT message OVERWRITES prior Redis value for same memberID — no append, no merge |
+| V11 | MQTT paho defaults apply: KeepAlive=30s, CleanSession=true, AutoReconnect=true |
+| V12 | Malformed env var (non-numeric `MQTT_REDIS_DB`/`MQTT_REDIS_SETEX`) → parseInt returns 0 silently |
+
+## §T Tasks
+
+| id | status | desc | cites |
+|----|--------|------|-------|
+| T1 | x | Add graceful shutdown (SIGTERM → disconnect MQTT → exit) | V8 |
+| T2 | x | Add tests for handleMessage parsing logic | V1,V2,V3,V4,V9,V10 |
+| T3 | x | Replace `golang.org/x/net/context` with stdlib `context` | — |
+| T4 | x | Add golangci-lint config and CI pipeline | — |
+| T5 | x | Add error metrics/logging for Redis SETEX failures | — |
+
+## §B Bugs
+
+| id | date | cause | fix |
+| B1 | 2026-09-03 | V9 stated "empty payload → no write" but `strings.Split("", ";")` returns `[""]` (len 1) — guard never fires. Empty payload writes to Redis. | V9 corrected |

mqtt_presence_redis_go/.golangci.yml

@@ -0,0 +1,15 @@
+linters:
+  enable:
+    - errcheck
+    - govet
+    - staticcheck
+    - unused
+    - ineffassign
+    - gosimple
+
+linters-settings:
+  errcheck:
+    check-blank: true
+
+run:
+  timeout: 5m

mqtt_presence_redis_go/Dockerfile

@@ -2,16 +2,12 @@
 
 # Build stage
 FROM golang:1.24-alpine AS builder
+RUN apk add --no-cache git
 WORKDIR /app
 
-# Copy go mod files and download dependencies
+# Copy source and resolve dependencies
-COPY go.mod go.sum ./
-RUN go mod download
-
-# Copy the rest of the application
 COPY . .
-
+RUN go mod tidy
-# Build the application
 RUN go build -o mqtt_presence_redis_go mqtt_presence_redis_go.go
 
 # Runtime stage
@@ -19,8 +15,5 @@ FROM alpine:3.20
 WORKDIR /app
 COPY --from=builder /app/mqtt_presence_redis_go .
 
-# Expose default MQTT port if needed
 EXPOSE 1883
-
-# Command to run the binary
 CMD ["./mqtt_presence_redis_go"]

mqtt_presence_redis_go/go.mod

@@ -3,14 +3,7 @@ module git.proit.id/dsutanto/backone-manage-go/mqtt_presence_redis_go
 go 1.24.3
 
 require (
+	github.com/alicebob/miniredis/v2 v2.34.0
 	github.com/eclipse/paho.mqtt.golang v1.5.1
 	github.com/go-redis/redis/v8 v8.11.5
-	golang.org/x/net v0.49.0
-)
-
-require (
-	github.com/cespare/xxhash/v2 v2.1.2 // indirect
-	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
-	github.com/gorilla/websocket v1.5.3 // indirect
-	golang.org/x/sync v0.17.0 // indirect
 )

mqtt_presence_redis_go/go.sum

@@ -1,30 +0,0 @@
-github.com/cespare/xxhash/v2 v2.1.2 h1:YRXhKfTDauu4ajMg1TPgFO5jnlC2HCbmLXMcTG5cbYE=
-github.com/cespare/xxhash/v2 v2.1.2/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
-github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f h1:lO4WD4F/rVNCu3HqELle0jiPLLBs70cWOduZpkS1E78=
-github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f/go.mod h1:cuUVRXasLTGF7a8hSLbxyZXjz+1KgoB3wDUb6vlszIc=
-github.com/eclipse/paho.mqtt.golang v1.5.1 h1:/VSOv3oDLlpqR2Epjn1Q7b2bSTplJIeV2ISgCl2W7nE=
-github.com/eclipse/paho.mqtt.golang v1.5.1/go.mod h1:1/yJCneuyOoCOzKSsOTUc0AJfpsItBGWvYpBLimhArU=
-github.com/fsnotify/fsnotify v1.4.9 h1:hsms1Qyu0jgnwNXIxa+/V/PDsU6CfLf6CNO8H7IWoS4=
-github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
-github.com/go-redis/redis/v8 v8.11.5 h1:AcZZR7igkdvfVmQTPnu9WE37LRrO/YrBH5zWyjDC0oI=
-github.com/go-redis/redis/v8 v8.11.5/go.mod h1:gREzHqY1hg6oD9ngVRbLStwAWKhA0FEgq8Jd4h5lpwo=
-github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
-github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
-github.com/nxadm/tail v1.4.8 h1:nPr65rt6Y5JFSKQO7qToXr7pePgD6Gwiw05lkbyAQTE=
-github.com/nxadm/tail v1.4.8/go.mod h1:+ncqLTQzXmGhMZNUePPaPqPvBxHAIsmXswZKocGu+AU=
-github.com/onsi/ginkgo v1.16.5 h1:8xi0RTUf59SOSfEtZMvwTvXYMzG4gV23XVHOZiXNtnE=
-github.com/onsi/ginkgo v1.16.5/go.mod h1:+E8gABHa3K6zRBolWtd+ROzc/U5bkGt0FwiG042wbpU=
-github.com/onsi/gomega v1.18.1 h1:M1GfJqGRrBrrGGsbxzV5dqM2U2ApXefZCQpkukxYRLE=
-github.com/onsi/gomega v1.18.1/go.mod h1:0q+aL8jAiMXy9hbwj2mr5GziHiwhAIQpFmmtT5hitRs=
-golang.org/x/net v0.49.0 h1:eeHFmOGUTtaaPSGNmjBKpbng9MulQsJURQUAfUwY++o=
-golang.org/x/net v0.49.0/go.mod h1:/ysNB2EvaqvesRkuLAyjI1ycPZlQHM3q01F02UY/MV8=
-golang.org/x/sync v0.17.0 h1:l60nONMj9l5drqw6jlhIELNv9I0A4OFgRsG9k2oT9Ug=
-golang.org/x/sync v0.17.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
-golang.org/x/sys v0.40.0 h1:DBZZqJ2Rkml6QMQsZywtnjnnGvHza6BTfYFWY9kjEWQ=
-golang.org/x/sys v0.40.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
-golang.org/x/text v0.33.0 h1:B3njUFyqtHDUI5jMn1YIr5B0IE2U0qck04r6d4KPAxE=
-golang.org/x/text v0.33.0/go.mod h1:LuMebE6+rBincTi9+xWTY8TztLzKHc/9C1uBCG27+q8=
-gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 h1:uRGJdciOHaEIrze2W8Q3AKkepLTh2hOroT7a+7czfdQ=
-gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWDmTeBkI65Dw0HsyUHuEVlX15mw=
-gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
-gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=

mqtt_presence_redis_go/mqtt_presence_redis_go.go

@@ -1,18 +1,20 @@
 package main
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"log"
+	"math/rand/v2"
 	"os"
-    "strings"
+	"os/signal"
-    "time"
 	"strconv"
-    "math/rand"
+	"strings"
+	"syscall"
+	"time"
 
 	mqtt "github.com/eclipse/paho.mqtt.golang"
 	"github.com/go-redis/redis/v8"
-    "golang.org/x/net/context"
 )
 
 // Configuration loaded from environment variables. These should match the
@@ -54,7 +56,6 @@ func main() {
 	opts.SetUsername(mqttUser)
 	opts.SetPassword(mqttPass)
 	opts.SetClientID(fmt.Sprintf("mqtt_presence_redis_go_%s", randomString()))
-    // clientID variable removed; use opts.ClientID directly
 
 	// Handlers
 	opts.SetDefaultPublishHandler(func(client mqtt.Client, msg mqtt.Message) {
@@ -74,8 +75,14 @@ func main() {
 		log.Fatalf("Could not connect to MQTT broker: %v", token.Error())
 	}
 
-    // Block forever
+	// Wait for shutdown signal
-    select {}
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
+	sig := <-sigCh
+	log.Printf("Received signal %v, disconnecting MQTT...", sig)
+	client.Disconnect(250)
+	log.Println("MQTT disconnected, exiting")
+	os.Exit(0)
 }
 
 func handleMessage(ctx context.Context, rdb *redis.Client, msg mqtt.Message) {
@@ -105,7 +112,7 @@ func handleMessage(ctx context.Context, rdb *redis.Client, msg mqtt.Message) {
 	}
 
 	if err := rdb.SetEX(ctx, key, data, time.Duration(parseInt(redisSetEX))*time.Second).Err(); err != nil {
-        log.Printf("Failed to set Redis key: %v", err)
+		log.Printf("Failed to set Redis key %q for memberID %q: %v", key, memberID, err)
 	}
 }
 
@@ -129,7 +136,7 @@ func randomString() string {
 	const letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
 	b := make([]byte, 10)
 	for i := range b {
-        b[i] = letters[rand.Intn(len(letters))]
+		b[i] = letters[rand.IntN(len(letters))]
 	}
 	return string(b)
 }

mqtt_presence_redis_go/mqtt_presence_redis_go_test.go

@@ -0,0 +1,239 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/alicebob/miniredis/v2"
+	"github.com/go-redis/redis/v8"
+)
+
+// fakeMsg implements mqtt.Message for testing.
+type fakeMsg struct {
+	payload []byte
+}
+
+func (f *fakeMsg) Payload() []byte    { return f.payload }
+func (f *fakeMsg) Topic() string      { return "" }
+func (f *fakeMsg) MessageID() uint16  { return 0 }
+func (f *fakeMsg) Retained() bool     { return false }
+func (f *fakeMsg) QoS() byte          { return 0 }
+func (f *fakeMsg) Duplicate() bool    { return false }
+func (f *fakeMsg) Ack()               {}
+func (f *fakeMsg) Confirm()           {}
+
+func setupRedis(t *testing.T) (*miniredis.Miniredis, *redis.Client) {
+	t.Helper()
+	mr, err := miniredis.Run()
+	if err != nil {
+		t.Fatalf("failed to start miniredis: %v", err)
+	}
+	t.Cleanup(mr.Close)
+
+	rdb := redis.NewClient(&redis.Options{Addr: mr.Addr()})
+	t.Cleanup(func() { rdb.Close() })
+
+	return mr, rdb
+}
+
+func TestHandleMessage_NormalPayload(t *testing.T) {
+	// V1: memberID = first segment before ";"
+	// V2: truncate to 50 chars
+	// V3: key = "presence:<memberID>"
+	// V4: value = JSON {mqtt, ts}
+	// V10: overwrites prior value
+	mr, rdb := setupRedis(t)
+	ctx := context.Background()
+
+	// Set default env values for test
+	redisPrefix = "presence"
+	redisSetEX = "86400"
+
+	payload := "member123;extra;data"
+	msg := &fakeMsg{payload: []byte(payload)}
+	handleMessage(ctx, rdb, msg)
+
+	key := "presence:member123"
+	val, err := rdb.Get(ctx, key).Result()
+	if err != nil {
+		t.Fatalf("key %q not found in Redis: %v", key, err)
+	}
+
+	var obj map[string]interface{}
+	if err := json.Unmarshal([]byte(val), &obj); err != nil {
+		t.Fatalf("value is not valid JSON: %v", err)
+	}
+
+	if obj["mqtt"] != payload {
+		t.Errorf("mqtt field = %q, want %q", obj["mqtt"], payload)
+	}
+
+	if _, ok := obj["ts"].(float64); !ok {
+		t.Errorf("ts field is not a number: %v", obj["ts"])
+	}
+}
+
+func TestHandleMessage_EmptyPayload(t *testing.T) {
+	// V9: empty payload → memberID = "" → key "presence:" → write still occurs
+	_, rdb := setupRedis(t)
+	ctx := context.Background()
+
+	redisPrefix = "presence"
+	redisSetEX = "86400"
+
+	msg := &fakeMsg{payload: []byte("")}
+	handleMessage(ctx, rdb, msg)
+
+	// Guard in code: len(parts)==0 → return. But strings.Split("", ";") returns [""]
+	// so memberID = "" and Redis write occurs.
+	key := "presence:"
+	exists := rdb.Exists(ctx, key).Val()
+	// Depending on code behavior: if the guard fires, exists==0; if not, exists==1.
+	// Current code: strings.Split("", ";") returns [""], len==1, guard does NOT fire.
+	// So empty payload DOES write. This test documents that behavior.
+	if exists != 1 {
+		t.Errorf("empty payload: expected Redis key %q to exist (V9 behavior), got exists=%d", key, exists)
+	}
+}
+
+func TestHandleMessage_NoSemicolon(t *testing.T) {
+	// V1: no ";" → memberID = entire payload
+	_, rdb := setupRedis(t)
+	ctx := context.Background()
+
+	redisPrefix = "p"
+	redisSetEX = "60"
+
+	msg := &fakeMsg{payload: []byte("abc123")}
+	handleMessage(ctx, rdb, msg)
+
+	val, err := rdb.Get(ctx, "p:abc123").Result()
+	if err != nil {
+		t.Fatalf("key not found: %v", err)
+	}
+	if val == "" {
+		t.Error("expected non-empty value")
+	}
+}
+
+func TestHandleMessage_LongMemberID(t *testing.T) {
+	// V2: memberID truncated to 50 chars
+	_, rdb := setupRedis(t)
+	ctx := context.Background()
+
+	redisPrefix = "presence"
+	redisSetEX = "86400"
+
+	longID := "abcdefghijklmnopqrstuvwxyz1234567890ABCDEFGHIJKLMN" // 53 chars
+	payload := longID + ";rest"
+	msg := &fakeMsg{payload: []byte(payload)}
+	handleMessage(ctx, rdb, msg)
+
+	expectedKey := "presence:" + longID[:50]
+	exists := rdb.Exists(ctx, expectedKey).Val()
+	if exists != 1 {
+		t.Errorf("expected key %q to exist after 50-char truncation", expectedKey)
+	}
+}
+
+func TestHandleMessage_Overwrite(t *testing.T) {
+	// V10: each message overwrites prior value for same memberID
+	_, rdb := setupRedis(t)
+	ctx := context.Background()
+
+	redisPrefix = "presence"
+	redisSetEX = "86400"
+
+	// First message
+	handleMessage(ctx, rdb, &fakeMsg{payload: []byte("m1;first")})
+	val1, _ := rdb.Get(ctx, "presence:m1").Result()
+
+	// Second message same memberID
+	handleMessage(ctx, rdb, &fakeMsg{payload: []byte("m1;second")})
+	val2, _ := rdb.Get(ctx, "presence:m1").Result()
+
+	if val1 == val2 {
+		t.Error("second message should overwrite first, but values are identical")
+	}
+
+	var obj map[string]interface{}
+	json.Unmarshal([]byte(val2), &obj)
+	if obj["mqtt"] != "m1;second" {
+		t.Errorf("after overwrite, mqtt = %q, want %q", obj["mqtt"], "m1;second")
+	}
+}
+
+func TestGetEnv_WithVar(t *testing.T) {
+	os.Setenv("TEST_GETENV_YES", "hello")
+	defer os.Unsetenv("TEST_GETENV_YES")
+
+	got := getEnv("TEST_GETENV_YES", "default")
+	if got != "hello" {
+		t.Errorf("getEnv = %q, want %q", got, "hello")
+	}
+}
+
+func TestGetEnv_WithoutVar(t *testing.T) {
+	os.Unsetenv("TEST_GETENV_NO")
+	got := getEnv("TEST_GETENV_NO", "fallback")
+	if got != "fallback" {
+		t.Errorf("getEnv = %q, want %q", got, "fallback")
+	}
+}
+
+func TestParseInt_Valid(t *testing.T) {
+	got := parseInt("42")
+	if got != 42 {
+		t.Errorf("parseInt(42) = %d, want 42", got)
+	}
+}
+
+func TestParseInt_Invalid(t *testing.T) {
+	// V12: malformed → returns 0, logs error
+	got := parseInt("not_a_number")
+	if got != 0 {
+		t.Errorf("parseInt(invalid) = %d, want 0", got)
+	}
+}
+
+func TestRandomString_Length(t *testing.T) {
+	// V6: random string is 10 chars
+	s := randomString()
+	if len(s) != 10 {
+		t.Errorf("randomString() len = %d, want 10", len(s))
+	}
+}
+
+func TestRandomString_Uniqueness(t *testing.T) {
+	// Two calls should (almost certainly) differ
+	a := randomString()
+	b := randomString()
+	if a == b {
+		t.Errorf("two randomString() calls returned same value: %q", a)
+	}
+}
+
+func TestHandleMessage_Timestamp(t *testing.T) {
+	// V4: ts is unix timestamp, roughly now
+	_, rdb := setupRedis(t)
+	ctx := context.Background()
+
+	redisPrefix = "presence"
+	redisSetEX = "86400"
+
+	before := time.Now().Unix()
+	handleMessage(ctx, rdb, &fakeMsg{payload: []byte("ts_test")})
+	after := time.Now().Unix()
+
+	val, _ := rdb.Get(ctx, "presence:ts_test").Result()
+	var obj map[string]interface{}
+	json.Unmarshal([]byte(val), &obj)
+
+	ts := int64(obj["ts"].(float64))
+	if ts < before || ts > after {
+		t.Errorf("timestamp %d not in range [%d, %d]", ts, before, after)
+	}
+}