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

@@ -1,7 +1,6 @@
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
 import { BrowserRouter, Routes, Route } from 'react-router-dom'
 import InventoryPage from './pages/InventoryPage'
-import FilamentDetailPage from './pages/FilamentDetailPage'
 
 const queryClient = new QueryClient()
 
@@ -17,7 +16,6 @@ export default function App() {
           <main className="p-4">
             <Routes>
               <Route path="/" element={<InventoryPage />} />
-              <Route path="/filament/:id" element={<FilamentDetailPage />} />
             </Routes>
           </main>
         </div>

frontend/src/pages/FilamentDetailPage.tsx

@@ -1,391 +0,0 @@
-import { useState } from 'react'
-import { useParams, useNavigate } from 'react-router-dom'
-import { useQuery, useQueryClient } from '@tanstack/react-query'
-import { ArrowLeft, Pencil, Trash2, AlertTriangle, Loader2, Archive } from 'lucide-react'
-import ColorSwatch from '../components/ColorSwatch'
-import { fetchFilamentById, fetchUsageLogs, deleteFilament } from '../services/filamentService'
-import type { UsageLog } from '../types/filament'
-
-export default function FilamentDetailPage() {
-  const { id } = useParams<{ id: string }>()
-  const spoolId = Number(id)
-  const navigate = useNavigate()
-  const queryClient = useQueryClient()
-  const [deleteConfirm, setDeleteConfirm] = useState(false)
-  const [deleting, setDeleting] = useState(false)
-
-  const {
-    data: spool,
-    isLoading: spoolLoading,
-    error: spoolError,
-    refetch: refetchSpool,
-  } = useQuery({
-    queryKey: ['filament', spoolId],
-    queryFn: () => fetchFilamentById(spoolId),
-    enabled: !isNaN(spoolId),
-  })
-
-  const {
-    data: usageLogs,
-    isLoading: usageLoading,
-    error: usageError,
-    refetch: refetchUsage,
-  } = useQuery({
-    queryKey: ['usage-logs', spoolId],
-    queryFn: () => fetchUsageLogs(spoolId),
-    enabled: !isNaN(spoolId),
-  })
-
-  const handleDelete = async () => {
-    setDeleting(true)
-    try {
-      await deleteFilament(spoolId)
-      queryClient.invalidateQueries({ queryKey: ['filaments'] })
-      navigate('/')
-    } catch {
-      setDeleting(false)
-      setDeleteConfirm(false)
-    }
-  }
-
-  // ── Loading state ──
-  if (spoolLoading) {
-    return (
-      <div className="flex flex-col items-center justify-center py-24 gap-3 text-slate-400">
-        <Loader2 size={32} className="animate-spin text-emerald-400" />
-        <span>Loading spool details…</span>
-      </div>
-    )
-  }
-
-  // ── Error state ──
-  if (spoolError || !spool) {
-    return (
-      <div className="flex flex-col items-center justify-center py-24 gap-4">
-        <div className="flex h-14 w-14 items-center justify-center rounded-full bg-red-900/30">
-          <AlertTriangle size={28} className="text-red-400" />
-        </div>
-        <p className="text-red-400 font-medium">Failed to load spool details.</p>
-        <div className="flex gap-3">
-          <button
-            onClick={() => refetchSpool()}
-            className="rounded-lg bg-slate-700 px-4 py-2 text-sm font-medium text-slate-200 hover:bg-slate-600 transition-colors"
-          >
-            Retry
-          </button>
-          <button
-            onClick={() => navigate('/')}
-            className="rounded-lg bg-slate-800 border border-slate-700 px-4 py-2 text-sm font-medium text-slate-300 hover:bg-slate-700 transition-colors"
-          >
-            Back to Inventory
-          </button>
-        </div>
-      </div>
-    )
-  }
-
-  const pctRemaining = spool.initial_grams > 0
-    ? (spool.remaining_grams / spool.initial_grams) * 100
-    : 0
-  const isLow = spool.remaining_grams <= (spool.low_stock_threshold_grams || 0)
-
-  return (
-    <div className="space-y-6">
-      {/* ── Header Bar ── */}
-      <div className="flex flex-col sm:flex-row sm:items-center sm:justify-between gap-3">
-        <button
-          onClick={() => navigate('/')}
-          className="inline-flex items-center gap-2 rounded-lg bg-slate-800 border border-slate-700 px-3 py-2 text-sm font-medium text-slate-200 hover:bg-slate-700 active:bg-slate-600 transition-colors w-fit"
-        >
-          <ArrowLeft size={16} />
-          Back to Inventory
-        </button>
-
-        <div className="flex items-center gap-2">
-          <button className="inline-flex items-center gap-2 rounded-lg bg-slate-700 px-4 py-2 text-sm font-semibold text-slate-200 hover:bg-slate-600 active:bg-slate-500 transition-colors">
-            <Pencil size={16} />
-            Edit
-          </button>
-          <button
-            onClick={() => setDeleteConfirm(true)}
-            className="inline-flex items-center gap-2 rounded-lg bg-red-900/30 border border-red-700 px-4 py-2 text-sm font-semibold text-red-300 hover:bg-red-900/50 active:bg-red-900/70 transition-colors"
-          >
-            <Trash2 size={16} />
-            Delete
-          </button>
-        </div>
-      </div>
-
-      {/* ── Spool Info Card ── */}
-      <div className="rounded-xl border border-slate-700 bg-slate-800 overflow-hidden">
-        {/* Card header */}
-        <div className="px-6 py-5 border-b border-slate-700 flex flex-col sm:flex-row sm:items-center sm:justify-between gap-3">
-          <div className="flex items-center gap-3">
-            <ColorSwatch colorHex={spool.color_hex} size={36} />
-            <div>
-              <h1 className="text-xl font-bold text-slate-100">{spool.name}</h1>
-              <p className="text-sm text-slate-400">
-                {spool.brand && <span>{spool.brand} · </span>}
-                {spool.diameter_mm}mm
-              </p>
-            </div>
-          </div>
-          <div>
-            {isLow ? (
-              <span className="inline-flex items-center gap-1.5 rounded-full bg-red-900/40 border border-red-700 px-3 py-1 text-sm font-medium text-red-300">
-                <AlertTriangle size={14} /> Low Stock
-              </span>
-            ) : (
-              <span className="inline-flex items-center gap-1.5 rounded-full bg-emerald-900/30 border border-emerald-700 px-3 py-1 text-sm font-medium text-emerald-300">
-                In Stock
-              </span>
-            )}
-          </div>
-        </div>
-
-        {/* Card body — 2-column grid */}
-        <div className="px-6 py-5 grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-3 gap-x-8 gap-y-4">
-          <DetailItem label="Material" value={spool.material_base?.name ?? '—'} />
-          <DetailItem label="Finish" value={spool.material_finish?.name ?? '—'} />
-          <DetailItem
-            label="Modifier"
-            value={spool.material_modifier?.name ?? 'None'}
-          />
-          <DetailItem label="Color" value={spool.color_hex.toUpperCase()} />
-          <DetailItem label="Brand" value={spool.brand || '—'} />
-          <DetailItem label="Diameter" value={`${spool.diameter_mm}mm`} />
-          <DetailItem
-            label="Remaining"
-            value={
-              <span className="font-semibold tabular-nums">
-                {spool.remaining_grams.toLocaleString()} g
-              </span>
-            }
-          />
-          <DetailItem
-            label="Initial"
-            value={`${spool.initial_grams.toLocaleString()} g`}
-          />
-          <DetailItem
-            label="Cost"
-            value={
-              spool.cost_usd != null
-                ? `$${spool.cost_usd.toFixed(2)}`
-                : '—'
-            }
-          />
-        </div>
-
-        {/* Progress Bar */}
-        <div className="px-6 pb-5 pt-1">
-          <div className="flex items-center justify-between text-sm mb-1.5">
-            <span className="text-slate-400">
-              <span className="text-slate-200 font-semibold tabular-nums">
-                {spool.remaining_grams.toLocaleString()}g
-              </span>{' '}
-              of {spool.initial_grams.toLocaleString()}g
-            </span>
-            <span className="text-slate-400 font-medium tabular-nums">
-              {pctRemaining.toFixed(1)}%
-            </span>
-          </div>
-          <div className="w-full h-3 rounded-full bg-slate-700 overflow-hidden">
-            <div
-              className={`h-full rounded-full transition-all duration-500 ${
-                pctRemaining <= 10
-                  ? 'bg-red-500'
-                  : pctRemaining <= 25
-                    ? 'bg-amber-500'
-                    : 'bg-emerald-500'
-              }`}
-              style={{ width: `${Math.min(100, pctRemaining)}%` }}
-            />
-          </div>
-        </div>
-      </div>
-
-      {/* ── Usage History ── */}
-      <div className="rounded-xl border border-slate-700 bg-slate-800 overflow-hidden">
-        <div className="px-6 py-4 border-b border-slate-700">
-          <h2 className="text-lg font-semibold text-slate-100">Usage History</h2>
-        </div>
-
-        {/* Loading sub-state */}
-        {usageLoading && (
-          <div className="px-6 py-8 text-center text-slate-400">
-            <Loader2 size={20} className="animate-spin inline mr-2" />
-            Loading usage history…
-          </div>
-        )}
-
-        {/* Usage error sub-state */}
-        {usageError && !usageLoading && (
-          <div className="px-6 py-8 text-center">
-            <p className="text-red-400 text-sm">
-              Failed to load usage history.
-            </p>
-            <button
-              onClick={() => refetchUsage()}
-              className="mt-2 text-sm text-emerald-400 hover:text-emerald-300 underline"
-            >
-              Retry
-            </button>
-          </div>
-        )}
-
-        {/* Empty state */}
-        {!usageLoading && !usageError && usageLogs && usageLogs.length === 0 && (
-          <div className="px-6 py-10 text-center">
-            <Archive size={32} className="mx-auto text-slate-600 mb-2" />
-            <p className="text-slate-400 text-sm">No usage recorded yet.</p>
-            <p className="text-slate-500 text-xs mt-1">
-              Usage data will appear here when this spool is used in print jobs.
-            </p>
-          </div>
-        )}
-
-        {/* Table — desktop */}
-        {!usageLoading && !usageError && usageLogs && usageLogs.length > 0 && (
-          <>
-            <div className="hidden md:block overflow-x-auto">
-              <table className="w-full text-sm">
-                <thead className="bg-slate-800/50 text-slate-300">
-                  <tr>
-                    <th className="px-6 py-3 text-left font-semibold">Date</th>
-                    <th className="px-6 py-3 text-left font-semibold">Print Job</th>
-                    <th className="px-6 py-3 text-right font-semibold">mm Extruded</th>
-                    <th className="px-6 py-3 text-right font-semibold">Grams Used</th>
-                    <th className="px-6 py-3 text-right font-semibold">Cost</th>
-                  </tr>
-                </thead>
-                <tbody className="divide-y divide-slate-700">
-                  {usageLogs.map((log: UsageLog) => (
-                    <tr
-                      key={log.id}
-                      className="hover:bg-slate-700/30 transition-colors"
-                    >
-                      <td className="px-6 py-3 text-slate-200 tabular-nums">
-                        {new Date(log.logged_at).toLocaleDateString('en-US', {
-                          year: 'numeric',
-                          month: 'short',
-                          day: 'numeric',
-                        })}
-                      </td>
-                      <td className="px-6 py-3 text-slate-300">
-                        {log.print_job_name || `Job #${log.print_job_id ?? log.id}`}
-                      </td>
-                      <td className="px-6 py-3 text-right text-slate-200 tabular-nums">
-                        {log.mm_extruded.toLocaleString()}
-                      </td>
-                      <td className="px-6 py-3 text-right text-slate-200 tabular-nums">
-                        {log.grams_used.toFixed(2)} g
-                      </td>
-                      <td className="px-6 py-3 text-right text-slate-200 tabular-nums">
-                        {log.cost_usd != null ? `$${log.cost_usd.toFixed(3)}` : '—'}
-                      </td>
-                    </tr>
-                  ))}
-                </tbody>
-              </table>
-            </div>
-
-            {/* Mobile cards */}
-            <div className="md:hidden divide-y divide-slate-700">
-              {usageLogs.map((log: UsageLog) => (
-                <div key={log.id} className="px-4 py-4 space-y-2">
-                  <div className="flex items-center justify-between">
-                    <span className="text-sm font-medium text-slate-200">
-                      {log.print_job_name || `Job #${log.print_job_id ?? log.id}`}
-                    </span>
-                    <span className="text-xs text-slate-400 tabular-nums">
-                      {new Date(log.logged_at).toLocaleDateString('en-US', {
-                        month: 'short',
-                        day: 'numeric',
-                      })}
-                    </span>
-                  </div>
-                  <div className="flex items-center justify-between text-sm">
-                    <span className="text-slate-400">
-                      Extruded:{' '}
-                      <span className="text-slate-300 tabular-nums">
-                        {log.mm_extruded.toLocaleString()} mm
-                      </span>
-                    </span>
-                    <span className="text-slate-400">
-                      Used:{' '}
-                      <span className="text-slate-300 tabular-nums">
-                        {log.grams_used.toFixed(2)} g
-                      </span>
-                    </span>
-                    <span className="text-slate-400">
-                      {log.cost_usd != null ? (
-                        <>
-                          Cost:{' '}
-                          <span className="text-slate-300 tabular-nums">
-                            ${log.cost_usd.toFixed(3)}
-                          </span>
-                        </>
-                      ) : (
-                        '—'
-                      )}
-                    </span>
-                  </div>
-                </div>
-              ))}
-            </div>
-          </>
-        )}
-      </div>
-
-      {/* ── Delete Confirmation Modal ── */}
-      {deleteConfirm && (
-        <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/60 backdrop-blur-sm p-4">
-          <div className="w-full max-w-sm rounded-xl bg-slate-800 border border-slate-700 p-6 shadow-2xl space-y-4">
-            <div className="flex items-center gap-3">
-              <div className="flex h-10 w-10 items-center justify-center rounded-full bg-red-900/30 flex-shrink-0">
-                <AlertTriangle size={20} className="text-red-400" />
-              </div>
-              <div>
-                <h3 className="text-lg font-semibold text-slate-100">
-                  Delete &ldquo;{spool.name}&rdquo;?
-                </h3>
-                <p className="text-sm text-slate-400">
-                  This permanently removes the spool and all usage history. This cannot be undone.
-                </p>
-              </div>
-            </div>
-            <div className="flex justify-end gap-3">
-              <button
-                onClick={() => setDeleteConfirm(false)}
-                disabled={deleting}
-                className="rounded-lg bg-slate-700 px-4 py-2 text-sm font-medium text-slate-200 hover:bg-slate-600 transition-colors disabled:opacity-50"
-              >
-                Cancel
-              </button>
-              <button
-                onClick={handleDelete}
-                disabled={deleting}
-                className="inline-flex items-center gap-2 rounded-lg bg-red-600 px-4 py-2 text-sm font-medium text-white hover:bg-red-500 transition-colors disabled:opacity-50"
-              >
-                {deleting && <Loader2 size={16} className="animate-spin" />}
-                {deleting ? 'Deleting…' : 'Delete'}
-              </button>
-            </div>
-          </div>
-        </div>
-      )}
-    </div>
-  )
-}
-
-/** Small detail row for the info card grid */
-function DetailItem({ label, value }: { label: string; value: React.ReactNode }) {
-  return (
-    <div>
-      <dt className="text-xs font-medium uppercase tracking-wider text-slate-500 mb-0.5">
-        {label}
-      </dt>
-      <dd className="text-sm text-slate-200">{value}</dd>
-    </div>
-  )
-}

frontend/src/services/filamentService.ts

@@ -1,5 +1,5 @@
 import axios from 'axios'
-import type { FilamentSpool, ListResponse, UsageLog, FilamentFilter } from '../types/filament'
+import type { FilamentSpool, ListResponse, FilamentFilter } from '../types/filament'
 
 const API_BASE = '/api'
 
@@ -19,16 +19,6 @@ export async function fetchFilaments(filter: FilamentFilter): Promise<ListRespon
   return res.data
 }
 
-export async function fetchFilamentById(id: number): Promise<FilamentSpool> {
-  const res = await axios.get<FilamentSpool>(`${API_BASE}/filaments/${id}`)
-  return res.data
-}
-
-export async function fetchUsageLogs(spoolId: number): Promise<UsageLog[]> {
-  const res = await axios.get<UsageLog[]>(`${API_BASE}/usage-logs?spool_id=${spoolId}`)
-  return res.data
-}
-
 export async function deleteFilament(id: number): Promise<void> {
   await axios.delete(`${API_BASE}/filaments/${id}`)
 }

frontend/src/types/filament.ts

@@ -59,19 +59,6 @@ export interface ListResponse<T> {
   offset: number
 }
 
-export interface UsageLog {
-  id: number
-  spool_id: number
-  print_job_id?: number
-  print_job_name?: string
-  mm_extruded: number
-  grams_used: number
-  cost_usd?: number
-  logged_at: string
-  notes?: string
-  created_at: string
-}
-
 export interface FilamentFilter {
   material?: string
   finish?: string