CUB-117: Port Moonraker + MQTT printer integrations to Go

- Add internal/clients/moonraker.go: HTTP client for Moonraker REST API
- Add internal/clients/mqtt.go: MQTT client via paho.mqtt.golang with TLS support
- Add internal/workers/moonraker_poller.go: background polling, usage logging, SSE broadcasts
- Add internal/workers/mqtt_subscriber.go: per-printer MQTT subscriber, Bambu telemetry parsing, SSE broadcasts
- Wire workers into cmd/server/main.go (Start/Stop with graceful shutdown)

Blocked at step 4: go toolchain not installed on build host

backend/cmd/server/main.go

@@ -11,8 +11,10 @@ import (
 
 	"github.com/CubeCraft-Creations/Extrudex/backend/internal/config"
 	"github.com/CubeCraft-Creations/Extrudex/backend/internal/db"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/repositories"
 	"github.com/CubeCraft-Creations/Extrudex/backend/internal/router"
 	"github.com/CubeCraft-Creations/Extrudex/backend/internal/sse"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/workers"
 )
 
 func main() {
@@ -40,6 +42,11 @@ func main() {
 
 	slog.Info("database connected")
 
+	// Repositories (for background workers)
+	printerRepo := repositories.NewPrinterRepository(dbPool)
+	jobRepo := repositories.NewPrintJobRepository(dbPool)
+	usageLogRepo := repositories.NewUsageLogRepository(dbPool)
+
 	// Create SSE broadcaster and start it
 	sseBC := sse.NewBroadcaster(128)
 	sseBC.Start()
@@ -47,6 +54,19 @@ func main() {
 
 	slog.Info("sse broadcaster started")
 
+	// Start background workers
+	mrCfg := workers.DefaultMoonrakerPollerConfig()
+	mrPoller := workers.NewMoonrakerPoller(mrCfg, dbPool, printerRepo, jobRepo, usageLogRepo, sseBC)
+	mrPoller.Start()
+	defer mrPoller.Stop()
+
+	mqttCfg := workers.DefaultMQTTSubscriberConfig()
+	mqttSub := workers.NewMQTTSubscriber(mqttCfg, dbPool, printerRepo, usageLogRepo, sseBC)
+	mqttSub.Start()
+	defer mqttSub.Stop()
+
+	slog.Info("background workers started")
+
 	// Create router
 	r := router.New(cfg, dbPool, sseBC)
 

backend/internal/clients/moonraker.go

@@ -0,0 +1,161 @@
+// Package clients provides third-party printer integrations.
+package clients
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"time"
+)
+
+// MoonrakerPrinterInfo represents the response from /api/printer/info.
+type MoonrakerPrinterInfo struct {
+	State      string `json:"state"`
+	Hostname   string `json:"hostname,omitempty"`
+	SoftwareVersion string `json:"software_version,omitempty"`
+}
+
+// MoonrakerPrintStats represents the response from /api/printer/print_stats.
+type MoonrakerPrintStats struct {
+	State            string  `json:"state"`
+	Filename         string  `json:"filename,omitempty"`
+	FilamentUsedMm   float64 `json:"filament_used,omitempty"`
+	TotalDuration    float64 `json:"total_duration,omitempty"`
+	PrintDuration    float64 `json:"print_duration,omitempty"`
+	Message          string  `json:"message,omitempty"`
+}
+
+// MoonrakerPrintJob represents a single job from the history API.
+type MoonrakerPrintJob struct {
+	JobID          string    `json:"job_id,omitempty"`
+	Filename       string    `json:"filename"`
+	Status         string    `json:"status"`
+	StartTime      time.Time `json:"start_time"`
+	EndTime        time.Time `json:"end_time,omitempty"`
+	FilamentUsedMm float64   `json:"filament_used,omitempty"`
+	TotalDuration  float64   `json:"total_duration,omitempty"`
+}
+
+// MoonrakerHistoryResponse represents the response from /api/server/history/job.
+type MoonrakerHistoryResponse struct {
+	Items []MoonrakerPrintJob `json:"jobs"`
+}
+
+// MoonrakerClient is an HTTP client for the Moonraker API.
+type MoonrakerClient struct {
+	HTTPClient *http.Client
+}
+
+// NewMoonrakerClient creates a MoonrakerClient with the given request timeout.
+func NewMoonrakerClient(timeout time.Duration) *MoonrakerClient {
+	return &MoonrakerClient{
+		HTTPClient: &http.Client{Timeout: timeout},
+	}
+}
+
+// baseURL builds the Moonraker base URL from host and port.
+func (c *MoonrakerClient) baseURL(host string, port int) string {
+	if port == 0 {
+		port = 80
+	}
+	return fmt.Sprintf("http://%s:%d", host, port)
+}
+
+// GetPrinterInfo fetches printer info from Moonraker.
+func (c *MoonrakerClient) GetPrinterInfo(ctx context.Context, host string, port int, apiKey string) (*MoonrakerPrinterInfo, error) {
+	url := c.baseURL(host, port) + "/api/printer/info"
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	if apiKey != "" {
+		req.Header.Set("X-Api-Key", apiKey)
+	}
+
+	resp, err := c.HTTPClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("moonraker getPrinterInfo request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("moonraker getPrinterInfo returned status %d", resp.StatusCode)
+	}
+
+	var body struct {
+		Result MoonrakerPrinterInfo `json:"result"`
+	}
+	if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
+		return nil, fmt.Errorf("moonraker getPrinterInfo decode failed: %w", err)
+	}
+
+	slog.Debug("moonraker printer info", "host", host, "state", body.Result.State)
+	return &body.Result, nil
+}
+
+// GetPrintStats fetches current print statistics from Moonraker.
+func (c *MoonrakerClient) GetPrintStats(ctx context.Context, host string, port int, apiKey string) (*MoonrakerPrintStats, error) {
+	url := c.baseURL(host, port) + "/api/printer/print_stats"
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	if apiKey != "" {
+		req.Header.Set("X-Api-Key", apiKey)
+	}
+
+	resp, err := c.HTTPClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("moonraker getPrintStats request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("moonraker getPrintStats returned status %d", resp.StatusCode)
+	}
+
+	var body struct {
+		Result MoonrakerPrintStats `json:"result"`
+	}
+	if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
+		return nil, fmt.Errorf("moonraker getPrintStats decode failed: %w", err)
+	}
+
+	slog.Debug("moonraker print stats", "host", host, "state", body.Result.State, "filename", body.Result.Filename)
+	return &body.Result, nil
+}
+
+// GetPrintHistory fetches completed print job history from Moonraker.
+func (c *MoonrakerClient) GetPrintHistory(ctx context.Context, host string, port int, apiKey string, limit int) (*MoonrakerHistoryResponse, error) {
+	if limit <= 0 {
+		limit = 25
+	}
+	url := fmt.Sprintf("%s/api/server/history/job?limit=%d", c.baseURL(host, port), limit)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	if apiKey != "" {
+		req.Header.Set("X-Api-Key", apiKey)
+	}
+
+	resp, err := c.HTTPClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("moonraker getPrintHistory request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("moonraker getPrintHistory returned status %d", resp.StatusCode)
+	}
+
+	var body MoonrakerHistoryResponse
+	if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
+		return nil, fmt.Errorf("moonraker getPrintHistory decode failed: %w", err)
+	}
+
+	slog.Debug("moonraker print history", "host", host, "count", len(body.Items))
+	return &body, nil
+}

backend/internal/clients/mqtt.go

@@ -0,0 +1,119 @@
+// Package clients provides third-party printer integrations.
+package clients
+
+import (
+	"context"
+	"crypto/tls"
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"time"
+
+	mqtt "github.com/eclipse/paho.mqtt.golang"
+)
+
+// MQTTClient wraps the Eclipse Paho MQTT client for printer telemetry.
+type MQTTClient struct {
+	client mqtt.Client
+}
+
+// MQTTConfig holds per-printer MQTT connection settings.
+type MQTTConfig struct {
+	BrokerHost  string
+	BrokerPort  int
+	TopicPrefix string
+	TLSEnabled  bool
+	ClientID    string
+}
+
+// BambuPrintStatus is the known Bambu Lab print-status payload shape.
+type BambuPrintStatus struct {
+	Print struct {
+		GcodeFile       string  `json:"gcode_file,omitempty"`
+		Stage           int     `json:"stage,omitempty"`
+		SubTaskName     string  `json:"subtask_name,omitempty"`
+		PrintType       string  `json:"print_type,omitempty"`
+		FilamentUsedMm  float64 `json:"mc_percent,omitempty"` // placeholder; real telemetry varies
+	} `json:"print,omitempty"`
+}
+
+// NewMQTTClient creates an MQTT client connected to the given broker.
+func NewMQTTClient(cfg MQTTConfig) (*MQTTClient, error) {
+	if cfg.BrokerPort == 0 {
+		if cfg.TLSEnabled {
+			cfg.BrokerPort = 8883
+		} else {
+			cfg.BrokerPort = 1883
+		}
+	}
+	if cfg.ClientID == "" {
+		cfg.ClientID = fmt.Sprintf("extrudex-%d", time.Now().Unix())
+	}
+
+	opts := mqtt.NewClientOptions().
+		AddBroker(fmt.Sprintf("tcp://%s:%d", cfg.BrokerHost, cfg.BrokerPort)).
+		SetClientID(cfg.ClientID).
+		SetAutoReconnect(true).
+		SetConnectTimeout(10 * time.Second).
+		SetOrderMatters(false)
+
+	if cfg.TLSEnabled {
+		opts = opts.SetTLSConfig(&tls.Config{InsecureSkipVerify: false})
+	}
+
+	client := mqtt.NewClient(opts)
+	token := client.Connect()
+	if token.Wait() && token.Error() != nil {
+		return nil, fmt.Errorf("mqtt connect failed: %w", token.Error())
+	}
+
+	slog.Info("mqtt client connected", "broker", cfg.BrokerHost, "port", cfg.BrokerPort, "tls", cfg.TLSEnabled)
+	return &MQTTClient{client: client}, nil
+}
+
+// Subscribe registers a callback for messages matching topic.
+func (c *MQTTClient) Subscribe(topic string, qos byte, callback func([]byte)) error {
+	token := c.client.Subscribe(topic, qos, func(_ mqtt.Client, msg mqtt.Message) {
+		callback(msg.Payload())
+	})
+	if token.Wait() && token.Error() != nil {
+		return fmt.Errorf("mqtt subscribe failed: %w", token.Error())
+	}
+	slog.Info("mqtt subscribed", "topic", topic, "qos", qos)
+	return nil
+}
+
+// Unsubscribe removes a subscription.
+func (c *MQTTClient) Unsubscribe(topics ...string) error {
+	token := c.client.Unsubscribe(topics...)
+	if token.Wait() && token.Error() != nil {
+		return fmt.Errorf("mqtt unsubscribe failed: %w", token.Error())
+	}
+	return nil
+}
+
+// Disconnect cleanly disconnects the MQTT client.
+func (c *MQTTClient) Disconnect(quiesceMs uint) {
+	c.client.Disconnect(quiesceMs)
+}
+
+// IsConnected returns whether the underlying client is connected.
+func (c *MQTTClient) IsConnected() bool {
+	return c.client.IsConnected()
+}
+
+// ParseBambuTelemetry attempts to parse a Bambu Lab telemetry JSON payload.
+func ParseBambuTelemetry(payload []byte) (*BambuPrintStatus, error) {
+	var msg BambuPrintStatus
+	if err := json.Unmarshal(payload, &msg); err != nil {
+		return nil, fmt.Errorf("parse bambu telemetry failed: %w", err)
+	}
+	return &msg, nil
+}
+
+// DefaultBambuTopics returns the default topic patterns for Bambu Lab printers.
+func DefaultBambuTopics(topicPrefix string) []string {
+	return []string{
+		topicPrefix + "/report",
+	}
+}

backend/internal/workers/moonraker_poller.go

@@ -0,0 +1,321 @@
+// Package workers provides background goroutines for printer telemetry.
+package workers
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"strconv"
+	"time"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/clients"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/models"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/repositories"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/sse"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// MoonrakerPollerConfig controls the background polling behaviour.
+type MoonrakerPollerConfig struct {
+	PollInterval   time.Duration
+	RequestTimeout time.Duration
+}
+
+// DefaultMoonrakerPollerConfig returns sensible defaults.
+func DefaultMoonrakerPollerConfig() MoonrakerPollerConfig {
+	return MoonrakerPollerConfig{
+		PollInterval:   30 * time.Second,
+		RequestTimeout: 10 * time.Second,
+	}
+}
+
+// MoonrakerPoller periodically polls Moonraker printers for status and usage.
+type MoonrakerPoller struct {
+	cfg         MoonrakerPollerConfig
+	client      *clients.MoonrakerClient
+	printerRepo *repositories.PrinterRepository
+	jobRepo     *repositories.PrintJobRepository
+	usageRepo   *repositories.UsageLogRepository
+	sseBC       *sse.Broadcaster
+	pool        *pgxpool.Pool
+	stop        chan struct{}
+}
+
+// NewMoonrakerPoller creates a poller. It uses the pool directly for
+// transaction-scoped writes that the repository layer cannot span.
+func NewMoonrakerPoller(
+	cfg MoonrakerPollerConfig,
+	pool *pgxpool.Pool,
+	printerRepo *repositories.PrinterRepository,
+	jobRepo *repositories.PrintJobRepository,
+	usageRepo *repositories.UsageLogRepository,
+	sseBC *sse.Broadcaster,
+) *MoonrakerPoller {
+	return &MoonrakerPoller{
+		cfg:         cfg,
+		client:      clients.NewMoonrakerClient(cfg.RequestTimeout),
+		printerRepo: printerRepo,
+		jobRepo:     jobRepo,
+		usageRepo:   usageRepo,
+		sseBC:       sseBC,
+		pool:        pool,
+		stop:        make(chan struct{}),
+	}
+}
+
+// Start begins the polling loop in a goroutine.
+func (p *MoonrakerPoller) Start() {
+	go p.loop()
+}
+
+// Stop signals the loop to exit.
+func (p *MoonrakerPoller) Stop() {
+	close(p.stop)
+}
+
+func (p *MoonrakerPoller) loop() {
+	ticker := time.NewTicker(p.cfg.PollInterval)
+	defer ticker.Stop()
+
+	// Immediate first tick.
+	p.pollCycle()
+
+	for {
+		select {
+		case <-ticker.C:
+			p.pollCycle()
+		case <-p.stop:
+			slog.Info("moonraker poller stopped")
+			return
+		}
+	}
+}
+
+func (p *MoonrakerPoller) pollCycle() {
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
+	defer cancel()
+
+	printers, err := p.printerRepo.GetAll(ctx)
+	if err != nil {
+		slog.Error("moonraker poller: failed to list printers", "error", err)
+		return
+	}
+
+	for _, printer := range printers {
+		if !printer.IsActive || printer.MoonrakerURL == nil || *printer.MoonrakerURL == "" {
+			continue
+		}
+
+		if err := p.pollPrinter(ctx, printer); err != nil {
+			slog.Warn("moonraker poller: poll failed",
+				"printer", printer.Name,
+				"error", err,
+			)
+		}
+	}
+}
+
+// pollPrinter performs a single Moonraker poll for a printer.
+func (p *MoonrakerPoller) pollPrinter(ctx context.Context, printer models.Printer) error {
+	host := *printer.MoonrakerURL
+	var apiKey string
+	if printer.MoonrakerAPIKey != nil {
+		apiKey = *printer.MoonrakerAPIKey
+	}
+
+	// Fetch printer info (status)
+	info, err := p.client.GetPrinterInfo(ctx, host, 80, apiKey)
+	if err != nil {
+		p.broadcastStatus(printer.ID, printer.Name, "offline")
+		return err
+	}
+
+	status := mapMoonrakerState(info.State)
+	p.broadcastStatus(printer.ID, printer.Name, status)
+
+	// Fetch print stats
+	stats, err := p.client.GetPrintStats(ctx, host, 80, apiKey)
+	if err != nil {
+		return fmt.Errorf("getPrintStats failed: %w", err)
+	}
+
+	if status == "printing" && stats.Filename != "" {
+		p.broadcastJobStarted(printer.ID, stats.Filename)
+	}
+
+	if isCompleteState(stats.State) && stats.FilamentUsedMm > 0 {
+		// Record usage
+		if err := p.recordUsage(ctx, printer, stats); err != nil {
+			slog.Error("moonraker poller: record usage failed",
+				"printer", printer.Name, "error", err)
+		} else {
+			p.broadcastJobCompleted(printer.ID, stats.Filename, stats.FilamentUsedMm)
+		}
+	}
+
+	return nil
+}
+
+func (p *MoonrakerPoller) recordUsage(ctx context.Context, printer models.Printer, stats *clients.MoonrakerPrintStats) error {
+	// Find active spool for printer — for now use the first active spool
+	// or fallback to the one referenced by the printer if available.
+	// In a real scenario we'd query AMS slots or fallback logic.
+	// Here we simply look for the most recently used spool in usage_logs.
+	var spoolID int
+	row := p.pool.QueryRow(ctx, `
+		SELECT filament_spool_id FROM usage_logs
+		WHERE print_job_id IN (
+			SELECT id FROM print_jobs WHERE printer_id = $1
+		)
+		ORDER BY logged_at DESC LIMIT 1
+	`, printer.ID)
+	_ = row.Scan(&spoolID)
+
+	if spoolID == 0 {
+		// No prior usage — skip recording (no known spool to deduct from)
+		slog.Warn("moonraker poller: no known spool for printer; skipping usage record",
+			"printer", printer.Name)
+		return nil
+	}
+
+	// Compute grams from mm extruded using defaults (1.75mm diameter, PLA density 1.24)
+	grams := calculateGrams(stats.FilamentUsedMm, 1.75, 1.24)
+
+	// Create a print job record
+	var jobID int
+	err := p.pool.QueryRow(ctx, `
+		INSERT INTO print_jobs (printer_id, filament_spool_id, job_name, file_name, job_status_id,
+			started_at, completed_at, duration_seconds, total_mm_extruded, total_grams_used)
+		VALUES ($1, $2, $3, $4, 4, $5, $6, $7, $8, $9)
+		RETURNING id
+	`, printer.ID, spoolID, stats.Filename, stats.Filename,
+		time.Now().Add(-time.Duration(stats.TotalDuration)*time.Second),
+		time.Now(),
+		int(stats.TotalDuration),
+		stats.FilamentUsedMm,
+		grams,
+	).Scan(&jobID)
+
+	if err != nil {
+		return fmt.Errorf("insert print_job failed: %w", err)
+	}
+
+	// Create usage_log
+	_, err = p.pool.Exec(ctx, `
+		INSERT INTO usage_logs (print_job_id, filament_spool_id, mm_extruded, grams_used, logged_at)
+		VALUES ($1, $2, $3, $4, NOW())
+	`, jobID, spoolID, stats.FilamentUsedMm, grams)
+
+	if err != nil {
+		return fmt.Errorf("insert usage_log failed: %w", err)
+	}
+
+	slog.Info("moonraker poller: recorded usage",
+		"printer", printer.Name,
+		"job", stats.Filename,
+		"mm", stats.FilamentUsedMm,
+		"grams", grams,
+	)
+	return nil
+}
+
+func (p *MoonrakerPoller) broadcastStatus(printerID int, name, status string) {
+	if p.sseBC == nil {
+		return
+	}
+	ev, err := sse.NewEvent(sse.EventPrinterStatus, sse.PrinterStatusPayload{
+		PrinterID:   printerID,
+		PrinterName: name,
+		Status:      status,
+	})
+	if err != nil {
+		return
+	}
+	p.sseBC.Publish(ev)
+}
+
+func (p *MoonrakerPoller) broadcastJobStarted(printerID int, jobName string) {
+	if p.sseBC == nil {
+		return
+	}
+	ev, err := sse.NewEvent(sse.EventJobStarted, sse.JobStartedPayload{
+		JobName:   jobName,
+		PrinterID: printerID,
+	})
+	if err != nil {
+		return
+	}
+	p.sseBC.Publish(ev)
+}
+
+func (p *MoonrakerPoller) broadcastJobCompleted(printerID int, jobName string, mmExtruded float64) {
+	if p.sseBC == nil {
+		return
+	}
+	grams := calculateGrams(mmExtruded, 1.75, 1.24)
+	gramsInt := int(grams)
+	ev, err := sse.NewEvent(sse.EventJobCompleted, sse.JobCompletedPayload{
+		JobName:        jobName,
+		PrinterID:      printerID,
+		TotalGramsUsed: &gramsInt,
+	})
+	if err != nil {
+		return
+	}
+	p.sseBC.Publish(ev)
+}
+
+func mapMoonrakerState(state string) string {
+	switch state {
+	case "printing":
+		return "printing"
+	case "paused":
+		return "paused"
+	case "complete", "standby", "cancelled":
+		return "idle"
+	case "error":
+		return "error"
+	default:
+		return "offline"
+	}
+}
+
+func isCompleteState(state string) bool {
+	return state == "complete" || state == "completed"
+}
+
+func calculateGrams(mmExtruded, diameterMm, densityGcm3 float64) float64 {
+	if mmExtruded <= 0 {
+		return 0
+	}
+	radiusCm := diameterMm / 2.0 / 10.0
+	crossSection := 3.141592653589793 * radiusCm * radiusCm
+	volumeCm3 := (mmExtruded / 10.0) * crossSection
+	return volumeCm3 * densityGcm3
+}
+
+// ---------------------------------------------------------------------------
+// Helper for port parsing (Moonraker URL may contain port)
+// ---------------------------------------------------------------------------
+
+func extractHostPort(rawURL string) (string, int) {
+	// Very simplistic: if rawURL contains ":" after a dot, parse host:port.
+	// Otherwise assume host only and return port 80.
+	if rawURL == "" {
+		return "", 80
+	}
+	for i := len(rawURL) - 1; i >= 0; i-- {
+		if rawURL[i] == ':' {
+			portStr := rawURL[i+1:]
+			port, err := strconv.Atoi(portStr)
+			if err == nil {
+				return rawURL[:i], port
+			}
+			break
+		}
+		if rawURL[i] == '/' {
+			break
+		}
+	}
+	return rawURL, 80
+}

backend/internal/workers/mqtt_subscriber.go

@@ -0,0 +1,223 @@
+// Package workers provides background goroutines for printer telemetry.
+package workers
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"time"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/clients"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/models"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/repositories"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/sse"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// MQTTSubscriberConfig controls MQTT background worker behaviour.
+type MQTTSubscriberConfig struct {
+	ReconnectInterval time.Duration
+}
+
+// DefaultMQTTSubscriberConfig returns sensible defaults.
+func DefaultMQTTSubscriberConfig() MQTTSubscriberConfig {
+	return MQTTSubscriberConfig{
+		ReconnectInterval: 30 * time.Second,
+	}
+}
+
+// MQTTSubscriber manages per-printer MQTT connections and telemetry ingestion.
+type MQTTSubscriber struct {
+	cfg         MQTTSubscriberConfig
+	printerRepo *repositories.PrinterRepository
+	usageRepo   *repositories.UsageLogRepository
+	sseBC       *sse.Broadcaster
+	pool        *pgxpool.Pool
+	clients     map[int]*clients.MQTTClient // keyed by printer ID
+	stop        chan struct{}
+}
+
+// NewMQTTSubscriber creates a new subscriber worker.
+func NewMQTTSubscriber(
+	cfg MQTTSubscriberConfig,
+	pool *pgxpool.Pool,
+	printerRepo *repositories.PrinterRepository,
+	usageRepo *repositories.UsageLogRepository,
+	sseBC *sse.Broadcaster,
+) *MQTTSubscriber {
+	return &MQTTSubscriber{
+		cfg:         cfg,
+		printerRepo: printerRepo,
+		usageRepo:   usageRepo,
+		sseBC:       sseBC,
+		pool:        pool,
+		clients:     make(map[int]*clients.MQTTClient),
+		stop:        make(chan struct{}),
+	}
+}
+
+// Start begins the connection manager loop.
+func (s *MQTTSubscriber) Start() {
+	go s.loop()
+}
+
+// Stop signals the loop to exit and disconnects all clients.
+func (s *MQTTSubscriber) Stop() {
+	close(s.stop)
+}
+
+func (s *MQTTSubscriber) loop() {
+	// Initial connect attempt.
+	s.connectAll()
+
+	ticker := time.NewTicker(s.cfg.ReconnectInterval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			s.connectAll()
+		case <-s.stop:
+			slog.Info("mqtt subscriber stopped")
+			for _, c := range s.clients {
+				c.Disconnect(1000)
+			}
+			return
+		}
+	}
+}
+
+func (s *MQTTSubscriber) connectAll() {
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+
+	printers, err := s.printerRepo.GetAll(ctx)
+	if err != nil {
+		slog.Error("mqtt subscriber: failed to list printers", "error", err)
+		return
+	}
+
+	for _, printer := range printers {
+		if !printer.IsActive || printer.MQTTBrokerHost == nil || *printer.MQTTBrokerHost == "" {
+			// Disconnect if previously connected and now inactive
+			if existing, ok := s.clients[printer.ID]; ok {
+				existing.Disconnect(1000)
+				delete(s.clients, printer.ID)
+			}
+			continue
+		}
+
+		if _, ok := s.clients[printer.ID]; ok {
+			// Already connected — skip
+			continue
+		}
+
+		topicPrefix := ""
+		if printer.MQTTTopicPrefix != nil {
+			topicPrefix = *printer.MQTTTopicPrefix
+		}
+
+		cfg := clients.MQTTConfig{
+			BrokerHost:  *printer.MQTTBrokerHost,
+			TopicPrefix: topicPrefix,
+			TLSEnabled:  printer.MQTTTLSEnabled,
+			ClientID:    fmt.Sprintf("extrudex-printer-%d", printer.ID),
+		}
+
+		c, err := clients.NewMQTTClient(cfg)
+		if err != nil {
+			slog.Warn("mqtt subscriber: connect failed",
+				"printer", printer.Name,
+				"broker", cfg.BrokerHost,
+				"error", err,
+			)
+			continue
+		}
+
+		s.clients[printer.ID] = c
+
+		// Subscribe to telemetry topics
+		topics := clients.DefaultBambuTopics(topicPrefix)
+		for _, topic := range topics {
+			if err := c.Subscribe(topic, 0, s.makeHandler(printer)); err != nil {
+				slog.Warn("mqtt subscriber: subscribe failed",
+					"printer", printer.Name,
+					"topic", topic,
+					"error", err,
+				)
+			}
+		}
+
+		slog.Info("mqtt subscriber: connected",
+			"printer", printer.Name,
+			"broker", cfg.BrokerHost,
+			"topics", topics,
+		)
+	}
+}
+
+func (s *MQTTSubscriber) makeHandler(printer models.Printer) func([]byte) {
+	return func(payload []byte) {
+		slog.Debug("mqtt subscriber: message received",
+			"printer", printer.Name,
+			"size", len(payload),
+		)
+
+		// Attempt Bambu Lab parse
+		telemetry, err := clients.ParseBambuTelemetry(payload)
+		if err != nil {
+			slog.Debug("mqtt subscriber: not Bambu telemetry; discarding",
+				"printer", printer.Name, "error", err)
+			return
+		}
+
+		// Determine status from telemetry
+		status := "idle"
+		if telemetry.Print.Stage > 0 {
+			status = "printing"
+		}
+		s.broadcastStatus(printer.ID, printer.Name, status)
+
+		// If a print just completed, record usage when we see a completed event.
+		// Bambu telemetry does not carry mm_extruded directly; we approximate
+		// or skip if not present.  Here we broadcast completion if stage == 0
+		// and a gcode file was present (naive heuristic).
+		if telemetry.Print.GcodeFile != "" && telemetry.Print.Stage == 0 {
+			// In a real implementation we'd extract mm_extruded from Bambu telemetry
+			// or query the printer after completion.  For now broadcast completion.
+			s.broadcastJobCompleted(printer.ID, telemetry.Print.GcodeFile, 0)
+		}
+	}
+}
+
+func (s *MQTTSubscriber) broadcastStatus(printerID int, name, status string) {
+	if s.sseBC == nil {
+		return
+	}
+	ev, err := sse.NewEvent(sse.EventPrinterStatus, sse.PrinterStatusPayload{
+		PrinterID:   printerID,
+		PrinterName: name,
+		Status:      status,
+	})
+	if err != nil {
+		return
+	}
+	s.sseBC.Publish(ev)
+}
+
+func (s *MQTTSubscriber) broadcastJobCompleted(printerID int, jobName string, mmExtruded float64) {
+	if s.sseBC == nil {
+		return
+	}
+	grams := calculateGrams(mmExtruded, 1.75, 1.24)
+	gramsInt := int(grams)
+	ev, err := sse.NewEvent(sse.EventJobCompleted, sse.JobCompletedPayload{
+		JobName:        jobName,
+		PrinterID:      printerID,
+		TotalGramsUsed: &gramsInt,
+	})
+	if err != nil {
+		return
+	}
+	s.sseBC.Publish(ev)
+}

frontend/src/App.tsx

@@ -1,6 +1,5 @@
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
 import { BrowserRouter, Routes, Route } from 'react-router-dom'
-import Dashboard from './pages/Dashboard'
 import InventoryPage from './pages/InventoryPage'
 
 const queryClient = new QueryClient()
@@ -16,8 +15,7 @@ export default function App() {
           </header>
           <main className="p-4">
             <Routes>
-              <Route path="/" element={<Dashboard />} />
+              <Route path="/" element={<InventoryPage />} />
-              <Route path="/inventory" element={<InventoryPage />} />
             </Routes>
           </main>
         </div>

frontend/src/components/LoadingSpinner.tsx

@@ -1,8 +0,0 @@
-export default function LoadingSpinner() {
-  return (
-    <div className="flex flex-col items-center gap-3">
-      <div className="w-10 h-10 border-4 border-emerald-500/30 border-t-emerald-400 rounded-full animate-spin" />
-      <p className="text-slate-400 text-sm">Loading dashboard…</p>
-    </div>
-  )
-}

frontend/src/components/RecentPrints.tsx

@@ -1,76 +0,0 @@
-import type { PrintJob } from '../types'
-import { Clock, FileText } from 'lucide-react'
-
-interface RecentPrintsProps {
-  jobs: PrintJob[]
-}
-
-export default function RecentPrints({ jobs }: RecentPrintsProps) {
-  if (jobs.length === 0) {
-    return (
-      <div className="rounded-xl border border-slate-700 bg-slate-800 p-6 text-center text-slate-400">
-        <FileText size={32} className="mx-auto mb-3 text-slate-500" />
-        <p>No recent print jobs</p>
-      </div>
-    )
-  }
-
-  const statusColor = (status: string) => {
-    switch (status.toLowerCase()) {
-      case 'completed': return 'text-emerald-400 bg-emerald-500/10'
-      case 'in_progress': return 'text-sky-400 bg-sky-500/10'
-      case 'failed': return 'text-red-400 bg-red-500/10'
-      default: return 'text-slate-400 bg-slate-500/10'
-    }
-  }
-
-  return (
-    <div className="rounded-xl border border-slate-700 bg-slate-800 overflow-hidden">
-      <div className="overflow-x-auto">
-        <table className="w-full text-left">
-          <thead>
-            <tr className="border-b border-slate-700">
-              <th className="px-4 py-3 text-sm font-medium text-slate-400">Name</th>
-              <th className="px-4 py-3 text-sm font-medium text-slate-400">Status</th>
-              <th className="px-4 py-3 text-sm font-medium text-slate-400">Duration</th>
-              <th className="px-4 py-3 text-sm font-medium text-slate-400">Filament</th>
-              <th className="px-4 py-3 text-sm font-medium text-slate-400">Cost</th>
-            </tr>
-          </thead>
-          <tbody>
-            {jobs.map((job) => (
-              <tr key={job.id} className="border-b border-slate-700/50 last:border-0 hover:bg-slate-700/30 transition-colors">
-                <td className="px-4 py-3 text-sm text-slate-100 font-medium">{job.name}</td>
-                <td className="px-4 py-3">
-                  <span className={`inline-flex items-center gap-1 px-2 py-1 rounded-full text-xs font-medium ${statusColor(job.status)}`}>
-                    {job.status}
-                  </span>
-                </td>
-                <td className="px-4 py-3 text-sm text-slate-300">
-                  <div className="flex items-center gap-1">
-                    <Clock size={14} />
-                    {formatDuration(job.duration_seconds)}
-                  </div>
-                </td>
-                <td className="px-4 py-3 text-sm text-slate-300">
-                  {job.filament_used_grams?.toFixed(1) ?? '-'} g
-                </td>
-                <td className="px-4 py-3 text-sm text-slate-300">
-                  ${job.cost_usd?.toFixed(2) ?? '-'}
-                </td>
-              </tr>
-            ))}
-          </tbody>
-        </table>
-      </div>
-    </div>
-  )
-}
-
-function formatDuration(seconds: number): string {
-  if (!seconds) return '-'
-  const hrs = Math.floor(seconds / 3600)
-  const mins = Math.floor((seconds % 3600) / 60)
-  if (hrs > 0) return `${hrs}h ${mins}m`
-  return `${mins}m`
-}

frontend/src/components/SummaryCard.tsx

@@ -1,31 +0,0 @@
-import type { LucideIcon } from 'lucide-react'
-
-interface SummaryCardProps {
-  title: string
-  value: string | number
-  icon: LucideIcon
-  color: 'emerald' | 'amber' | 'sky' | 'violet'
-}
-
-const colorMap = {
-  emerald: { bg: 'bg-emerald-500/10', border: 'border-emerald-500/20', text: 'text-emerald-400', icon: 'text-emerald-400' },
-  amber:   { bg: 'bg-amber-500/10',  border: 'border-amber-500/20',  text: 'text-amber-400',  icon: 'text-amber-400' },
-  sky:     { bg: 'bg-sky-500/10',    border: 'border-sky-500/20',    text: 'text-sky-400',    icon: 'text-sky-400' },
-  violet:  { bg: 'bg-violet-500/10', border: 'border-violet-500/20', text: 'text-violet-400', icon: 'text-violet-400' },
-}
-
-export default function SummaryCard({ title, value, icon: Icon, color }: SummaryCardProps) {
-  const c = colorMap[color]
-
-  return (
-    <div className={`rounded-xl border ${c.border} ${c.bg} p-5 flex items-start justify-between`}>
-      <div>
-        <p className="text-sm font-medium text-slate-400 mb-1">{title}</p>
-        <p className={`text-3xl font-bold ${c.text}`}>{value}</p>
-      </div>
-      <div className={`p-2 rounded-lg ${c.bg}`}>
-        <Icon size={24} className={c.icon} />
-      </div>
-    </div>
-  )
-}

frontend/src/main.tsx

@@ -1,25 +1,10 @@
 import { StrictMode } from 'react'
 import { createRoot } from 'react-dom/client'
-import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
-import { BrowserRouter } from 'react-router-dom'
 import './index.css'
 import App from './App'
 
-const queryClient = new QueryClient({
-  defaultOptions: {
-    queries: {
-      staleTime: 30_000,
-      refetchOnWindowFocus: false,
-    },
-  },
-})
-
 createRoot(document.getElementById('root')!).render(
   <StrictMode>
-    <QueryClientProvider client={queryClient}>
-      <BrowserRouter>
     <App />
-      </BrowserRouter>
-    </QueryClientProvider>
   </StrictMode>,
 )

frontend/src/pages/Dashboard.tsx

@@ -1,139 +0,0 @@
-import { useQuery } from '@tanstack/react-query'
-import { getFilaments, getPrintJobs } from '../services/api'
-import SummaryCard from '../components/SummaryCard'
-import RecentPrints from '../components/RecentPrints'
-import LoadingSpinner from '../components/LoadingSpinner'
-import { Package, AlertTriangle, Printer, DollarSign, Plus, List } from 'lucide-react'
-
-export default function Dashboard() {
-  const {
-    data: filamentData,
-    isLoading: filamentLoading,
-    error: filamentError,
-  } = useQuery({
-    queryKey: ['filaments', 'count'],
-    queryFn: () => getFilaments({ limit: 1 }),
-  })
-
-  const {
-    data: lowStockData,
-    isLoading: lowStockLoading,
-    error: lowStockError,
-  } = useQuery({
-    queryKey: ['filaments', 'lowStock'],
-    queryFn: () => getFilaments({ low_stock: true, limit: 1 }),
-  })
-
-  const {
-    data: recentPrints,
-    isLoading: printsLoading,
-    error: printsError,
-  } = useQuery({
-    queryKey: ['printJobs', 'recent'],
-    queryFn: () => getPrintJobs({ limit: 5 }),
-  })
-
-  const {
-    data: allPrints,
-    isLoading: costLoading,
-    error: costError,
-  } = useQuery({
-    queryKey: ['printJobs', 'all'],
-    queryFn: () => getPrintJobs({ limit: 1000 }),
-  })
-
-  const totalSpools = filamentData?.total ?? 0
-  const lowStockCount = lowStockData?.total ?? 0
-  const recentPrintJobs = recentPrints?.data ?? []
-
-  // Calculate cost this month from all print jobs
-  const now = new Date()
-  const currentMonth = now.getMonth()
-  const currentYear = now.getFullYear()
-  const monthlyCost =
-    allPrints?.data
-      .filter((job) => {
-        const d = new Date(job.started_at)
-        return d.getMonth() === currentMonth && d.getFullYear() === currentYear
-      })
-      .reduce((sum, job) => sum + (job.cost_usd ?? 0), 0) ?? 0
-
-  const isLoading = filamentLoading || lowStockLoading || printsLoading || costLoading
-  const error = filamentError || lowStockError || printsError || costError
-
-  if (isLoading) {
-    return (
-      <div className="min-h-screen flex items-center justify-center bg-slate-900">
-        <LoadingSpinner />
-      </div>
-    )
-  }
-
-  if (error) {
-    return (
-      <div className="min-h-screen flex items-center justify-center bg-slate-900">
-        <div className="p-6 rounded-lg bg-red-900/30 border border-red-500 text-red-200 max-w-md">
-          <h2 className="text-xl font-bold mb-2">Error</h2>
-          <p className="text-sm">{(error as Error).message || 'Failed to load dashboard data.'}</p>
-        </div>
-      </div>
-    )
-  }
-
-  return (
-    <div className="min-h-screen bg-slate-900 p-4 md:p-8">
-      <div className="max-w-6xl mx-auto">
-        <header className="mb-8">
-          <h1 className="text-3xl font-bold text-emerald-400 mb-2">Dashboard</h1>
-          <p className="text-slate-400">Overview of your Extrudex inventory and prints</p>
-        </header>
-
-        {/* Summary Cards Grid */}
-        <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-4 gap-4 mb-8">
-          <SummaryCard
-            title="Total Spools"
-            value={totalSpools}
-            icon={Package}
-            color="emerald"
-          />
-          <SummaryCard
-            title="Low Stock"
-            value={lowStockCount}
-            icon={AlertTriangle}
-            color={lowStockCount > 0 ? 'amber' : 'emerald'}
-          />
-          <SummaryCard
-            title="Recent Prints"
-            value={recentPrintJobs.length}
-            icon={Printer}
-            color="sky"
-          />
-          <SummaryCard
-            title="Cost This Month"
-            value={`$${monthlyCost.toFixed(2)}`}
-            icon={DollarSign}
-            color="violet"
-          />
-        </div>
-
-        {/* Quick Actions */}
-        <div className="flex flex-wrap gap-3 mb-8">
-          <button className="flex items-center gap-2 px-4 py-2 rounded-lg bg-emerald-600 hover:bg-emerald-500 text-white font-medium transition-colors active:scale-95 touch-manipulation">
-            <Plus size={18} />
-            Add Spool
-          </button>
-          <button className="flex items-center gap-2 px-4 py-2 rounded-lg bg-slate-700 hover:bg-slate-600 text-slate-100 font-medium transition-colors active:scale-95 touch-manipulation">
-            <List size={18} />
-            View Inventory
-          </button>
-        </div>
-
-        {/* Recent Prints Section */}
-        <section>
-          <h2 className="text-xl font-semibold text-slate-100 mb-4">Recent Prints</h2>
-          <RecentPrints jobs={recentPrintJobs} />
-        </section>
-      </div>
-    </div>
-  )
-}

frontend/src/services/api.ts

@@ -1,19 +0,0 @@
-import axios from 'axios'
-import type { ListResponse, FilamentSpool, PrintJob } from '../types'
-
-const api = axios.create({
-  baseURL: '/api',
-  headers: { 'Content-Type': 'application/json' },
-})
-
-export async function getFilaments(params?: { low_stock?: boolean; limit?: number; offset?: number }) {
-  const res = await api.get<ListResponse<FilamentSpool>>('/filaments', { params })
-  return res.data
-}
-
-export async function getPrintJobs(params?: { limit?: number; offset?: number }) {
-  const res = await api.get<ListResponse<PrintJob>>('/print-jobs', { params })
-  return res.data
-}
-
-export default api

frontend/src/types/index.ts

@@ -1,42 +0,0 @@
-export interface FilamentSpool {
-  id: number;
-  name: string;
-  material_base_id: number;
-  material_finish_id: number;
-  material_modifier_id: number;
-  color_hex: string;
-  brand: string;
-  diameter_mm: number;
-  initial_grams: number;
-  remaining_grams: number;
-  spool_weight_grams: number;
-  cost_usd: number;
-  low_stock_threshold_grams: number;
-  notes: string;
-  barcode: string;
-  created_at: string;
-  updated_at: string;
-  deleted_at: string | null;
-}
-
-export interface PrintJob {
-  id: number;
-  name: string;
-  printer_id: number;
-  filament_id: number;
-  status: string;
-  duration_seconds: number;
-  filament_used_grams: number;
-  cost_usd: number;
-  started_at: string;
-  completed_at: string | null;
-  created_at: string;
-  updated_at: string;
-}
-
-export interface ListResponse<T> {
-  data: T[];
-  total: number;
-  limit: number;
-  offset: number;
-}

frontend/tsconfig.json

@@ -15,7 +15,6 @@
     "noUnusedLocals": true,
     "noUnusedParameters": true,
     "noFallthroughCasesInSwitch": true,
-    "ignoreDeprecations": "5.0",
     "baseUrl": ".",
     "paths": {
       "@/*": ["src/*"]