Merge pull request 'CUB-132: Build Filament Inventory list page with search and filters' (#43) from agent/Rex/CUB-132-filament-inventory-list into dev

Reviewed-on: #41

backend/Dockerfile

@@ -1,37 +1,25 @@
-# ── Stage 1: Build ──────────────────────────────────────────
+# Build stage
-FROM mcr.microsoft.com/dotnet/sdk:9.0 AS build
+FROM golang:1.24-alpine AS builder
-WORKDIR /src
 
-# Copy csproj first for layer caching — restores before copying source
-COPY Extrudex.csproj .
-RUN dotnet restore
-
-# Copy the rest of the source
-COPY . .
-RUN dotnet publish Extrudex.csproj \
-    -c Release \
-    -o /app/publish \
-    --no-restore
-
-# ── Stage 2: Runtime ────────────────────────────────────────
-FROM mcr.microsoft.com/dotnet/aspnet:9.0 AS runtime
 WORKDIR /app
 
-# Install curl for health check (not included in aspnet base image)
+# Copy go mod files first for caching
-RUN apt-get update && apt-get install -y --no-install-recommends curl && rm -rf /var/lib/apt/lists/*
+COPY go.mod go.sum ./
+RUN go mod download
 
-# Non-root user for security
+# Copy source and build
-RUN adduser --disabled-password --gecos "" appuser
+COPY . .
-USER appuser
+RUN CGO_ENABLED=0 GOOS=linux go build -o server ./cmd/server
 
-# Copy published output from build stage
+# Final stage
-COPY --from=build /app/publish .
+FROM alpine:latest
+RUN apk --no-cache add ca-certificates
+
+WORKDIR /root/
+
+# Copy binary from builder
+COPY --from=builder /app/server .
 
-# ASP.NET Core listens on 8080 by default in .NET 8+
 EXPOSE 8080
 
-# Health check against /health endpoint
+CMD ["./server"]
-HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
-    CMD curl --fail http://localhost:8080/health || exit 1
-
-ENTRYPOINT ["dotnet", "Extrudex.dll"]

backend/cmd/server/main.go

@@ -0,0 +1,90 @@
+package main
+
+import (
+	"context"
+	"log/slog"
+	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/config"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/db"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/router"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/sse"
+)
+
+func main() {
+	// Setup structured logging
+	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{
+		Level: slog.LevelInfo,
+	})))
+
+	// Load configuration
+	cfg, err := config.Load()
+	if err != nil {
+		slog.Error("failed to load config", "error", err)
+		os.Exit(1)
+	}
+
+	slog.Info("config loaded", "port", cfg.Port, "cors_origin", cfg.CorsOrigin)
+
+	// Connect to database
+	dbPool, err := db.NewPool(cfg.DatabaseURL)
+	if err != nil {
+		slog.Error("failed to connect to database", "error", err)
+		os.Exit(1)
+	}
+	defer db.ClosePool(dbPool)
+
+	slog.Info("database connected")
+
+	// Create SSE broadcaster and start it
+	sseBC := sse.NewBroadcaster(128)
+	sseBC.Start()
+	defer sseBC.Stop()
+
+	slog.Info("sse broadcaster started")
+
+	// Create router
+	r := router.New(cfg, dbPool, sseBC)
+
+	// Create HTTP server
+	// WriteTimeout is 0 for SSE support — the Chi middleware.Timeout(60s)
+	// handles request-level timeouts on non-SSE routes.
+	server := &http.Server{
+		Addr:         ":" + cfg.Port,
+		Handler:      r,
+		ReadTimeout:  15 * time.Second,
+		WriteTimeout: 0, // disabled for SSE long-lived connections
+		IdleTimeout:  60 * time.Second,
+	}
+
+	// Start server in goroutine
+	go func() {
+		slog.Info("server starting", "addr", server.Addr)
+		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+			slog.Error("server error", "error", err)
+			os.Exit(1)
+		}
+	}()
+
+	// Wait for shutdown signal
+	quit := make(chan os.Signal, 1)
+	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
+	<-quit
+
+	slog.Info("server shutting down")
+
+	// Graceful shutdown
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+
+	if err := server.Shutdown(ctx); err != nil {
+		slog.Error("server shutdown error", "error", err)
+	}
+
+	db.ClosePool(dbPool)
+	slog.Info("server stopped")
+}

backend/go.mod

@@ -0,0 +1,18 @@
+module github.com/CubeCraft-Creations/Extrudex/backend
+
+go 1.24
+
+require (
+	github.com/go-chi/chi/v5 v5.2.0
+	github.com/jackc/pgx/v5 v5.7.4
+	github.com/kelseyhightower/envconfig v1.4.0
+)
+
+require (
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
+	github.com/jackc/puddle/v2 v2.2.2 // indirect
+	golang.org/x/crypto v0.31.0 // indirect
+	golang.org/x/sync v0.10.0 // indirect
+	golang.org/x/text v0.21.0 // indirect
+)

backend/go.sum

@@ -0,0 +1,32 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-chi/chi/v5 v5.2.0 h1:Aj1EtB0qR2Rdo2dG4O94RIU35w2lvQSj6BRA4+qwFL0=
+github.com/go-chi/chi/v5 v5.2.0/go.mod h1:DslCQbL2OYiznFReuXYUmQ2hGd1aDpCnlMNITLSKoi8=
+github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
+github.com/jackc/pgpassfile v1.0.0/go.mod h1:CEx0iS5ambNFdcRtxPj5JhEz+xB6uRky5eyVu/W2HEg=
+github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 h1:iCEnooe7UlwOQYpKFhBabPMi4aNAfoODPEFNiAnClxo=
+github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761/go.mod h1:5TJZWKEWniPve33vlWYSoGYefn3gLQRzjfDlhSJ9ZKM=
+github.com/jackc/pgx/v5 v5.7.4 h1:9wKznZrhWa2QiHL+NjTSPP6yjl3451BX3imWDnokYlg=
+github.com/jackc/pgx/v5 v5.7.4/go.mod h1:ncY89UGWxg82EykZUwSpUKEfccBGGYq1xjrOpsbsfGQ=
+github.com/jackc/puddle/v2 v2.2.2 h1:PR8nw+E/1w0GLuRFSmiioY6UooMp6KJv0/61nB7icHo=
+github.com/jackc/puddle/v2 v2.2.2/go.mod h1:vriiEXHvEE654aYKXXjOvZM39qJ0q+azkZFrfEOc3H4=
+github.com/kelseyhightower/envconfig v1.4.0 h1:Im6hONhd3pLkfDFsbRgu68RDNkGF1r3dvMUtDTo2cv8=
+github.com/kelseyhightower/envconfig v1.4.0/go.mod h1:cccZRl6mQpaq41TPp5QxidR+Sa3axMbJDNb//FQX6Gg=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
+github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+golang.org/x/crypto v0.31.0 h1:ihbySMvVjLAeSH1IbfcRTkD/iNscyz8rGzjF/E5hV6U=
+golang.org/x/crypto v0.31.0/go.mod h1:kDsLvtWBEx7MV9tJOj9bnXsPbxwJQ6csT/x4KIN4Ssk=
+golang.org/x/sync v0.10.0 h1:3NQrjDixjgGwUOCaF8w2+VYHv0Ve/vGYSbdkTa98gmQ=
+golang.org/x/sync v0.10.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/text v0.21.0 h1:zyQAAkrwaneQ066sspRyJaG9VNi/YJ1NfzcGB3hZ/qo=
+golang.org/x/text v0.21.0/go.mod h1:4IBbMaMmOPCJ8SecivzSH54+73PCFmPWxNTLm+vZkEQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

backend/internal/config/config.go

@@ -0,0 +1,24 @@
+package config
+
+import (
+	"fmt"
+
+	"github.com/kelseyhightower/envconfig"
+)
+
+// Config holds all application configuration loaded from environment variables.
+type Config struct {
+	DatabaseURL string `envconfig:"database_url" required:"true"`
+	Port        string `envconfig:"port" default:"8080"`
+	CorsOrigin  string `envconfig:"cors_origin" default:"*"`
+	LogLevel    string `envconfig:"log_level" default:"info"`
+}
+
+// Load reads configuration from environment variables and returns a populated Config.
+func Load() (*Config, error) {
+	var cfg Config
+	if err := envconfig.Process("", &cfg); err != nil {
+		return nil, fmt.Errorf("failed to load config: %w", err)
+	}
+	return &cfg, nil
+}

backend/internal/db/db.go

@@ -0,0 +1,34 @@
+package db
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// NewPool creates a new pgx connection pool and verifies connectivity with a ping.
+func NewPool(databaseURL string) (*pgxpool.Pool, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	pool, err := pgxpool.New(ctx, databaseURL)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create db pool: %w", err)
+	}
+
+	if err := pool.Ping(ctx); err != nil {
+		pool.Close()
+		return nil, fmt.Errorf("failed to ping db: %w", err)
+	}
+
+	return pool, nil
+}
+
+// ClosePool gracefully closes the connection pool.
+func ClosePool(pool *pgxpool.Pool) {
+	if pool != nil {
+		pool.Close()
+	}
+}

backend/internal/dtos/dtos.go

@@ -0,0 +1,67 @@
+// Package dtos defines request/response data transfer objects for the Extrudex API.
+// DTOs keep HTTP serialization concerns separate from domain models.
+package dtos
+
+// ============================================================================
+// Common Response Wrappers
+// ============================================================================
+
+// ListResponse wraps a paginated collection response.
+type ListResponse struct {
+	Data   any `json:"data"`
+	Total  int `json:"total"`
+	Limit  int `json:"limit"`
+	Offset int `json:"offset"`
+}
+
+// SingleResponse wraps a single-item response.
+type SingleResponse struct {
+	Data any `json:"data"`
+}
+
+// ErrorResponse is the standard error payload for all API errors.
+type ErrorResponse struct {
+	Error string `json:"error"`
+	Code  int    `json:"code"`
+}
+
+// ============================================================================
+// Filament DTOs
+// ============================================================================
+
+// CreateFilamentRequest is the POST body for creating a new filament spool.
+type CreateFilamentRequest struct {
+	Name                  string  `json:"name"`
+	MaterialBaseID        int     `json:"material_base_id"`
+	MaterialFinishID      int     `json:"material_finish_id"`
+	MaterialModifierID    *int    `json:"material_modifier_id,omitempty"`
+	ColorHex             string  `json:"color_hex"`
+	Brand                *string `json:"brand,omitempty"`
+	DiameterMM           *float64 `json:"diameter_mm,omitempty"` // defaults to 1.75
+	InitialGrams         int     `json:"initial_grams"`
+	RemainingGrams       int     `json:"remaining_grams"`
+	SpoolWeightGrams     *int    `json:"spool_weight_grams,omitempty"`
+	CostUSD              *float64 `json:"cost_usd,omitempty"`
+	LowStockThresholdGrams *int  `json:"low_stock_threshold_grams,omitempty"` // defaults to 50
+	Notes                *string `json:"notes,omitempty"`
+	Barcode              *string `json:"barcode,omitempty"`
+}
+
+// UpdateFilamentRequest is the PUT body for partially updating a filament spool.
+// All fields are optional — only non-nil fields are applied.
+type UpdateFilamentRequest struct {
+	Name                  *string  `json:"name,omitempty"`
+	MaterialBaseID        *int     `json:"material_base_id,omitempty"`
+	MaterialFinishID      *int     `json:"material_finish_id,omitempty"`
+	MaterialModifierID    *int     `json:"material_modifier_id,omitempty"`
+	ColorHex             *string  `json:"color_hex,omitempty"`
+	Brand                *string  `json:"brand,omitempty"`
+	DiameterMM           *float64 `json:"diameter_mm,omitempty"`
+	InitialGrams         *int     `json:"initial_grams,omitempty"`
+	RemainingGrams       *int     `json:"remaining_grams,omitempty"`
+	SpoolWeightGrams     *int     `json:"spool_weight_grams,omitempty"`
+	CostUSD              *float64 `json:"cost_usd,omitempty"`
+	LowStockThresholdGrams *int   `json:"low_stock_threshold_grams,omitempty"`
+	Notes                *string  `json:"notes,omitempty"`
+	Barcode              *string  `json:"barcode,omitempty"`
+}

backend/internal/handlers/filament_handler.go

@@ -0,0 +1,273 @@
+package handlers
+
+import (
+	"encoding/json"
+	"log/slog"
+	"net/http"
+	"strconv"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/dtos"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/models"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/repositories"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/services"
+	"github.com/go-chi/chi/v5"
+)
+
+// FilamentHandler handles HTTP requests for filament spool CRUD operations.
+type FilamentHandler struct {
+	service *services.FilamentService
+}
+
+// NewFilamentHandler creates a FilamentHandler with the given service.
+func NewFilamentHandler(service *services.FilamentService) *FilamentHandler {
+	return &FilamentHandler{service: service}
+}
+
+// List handles GET /api/filaments — returns paginated, filtered spools.
+func (h *FilamentHandler) List(w http.ResponseWriter, r *http.Request) {
+	limit, offset := parsePagination(r)
+	filter := repositories.FilamentFilter{
+		Material: r.URL.Query().Get("material"),
+		Finish:   r.URL.Query().Get("finish"),
+		Color:    r.URL.Query().Get("color"),
+		LowStock: r.URL.Query().Get("low_stock") == "true",
+		Limit:    limit,
+		Offset:   offset,
+	}
+
+	spools, total, err := h.service.List(r.Context(), filter)
+	if err != nil {
+		slog.Error("failed to list filaments", "error", err)
+		writeJSON(w, http.StatusInternalServerError, dtos.ErrorResponse{
+			Error: "internal server error",
+			Code:  http.StatusInternalServerError,
+		})
+		return
+	}
+
+	writeJSON(w, http.StatusOK, dtos.ListResponse{
+		Data:   spools,
+		Total:  total,
+		Limit:  limit,
+		Offset: offset,
+	})
+}
+
+// Get handles GET /api/filaments/{id} — returns a single spool.
+func (h *FilamentHandler) Get(w http.ResponseWriter, r *http.Request) {
+	id, err := strconv.Atoi(chi.URLParam(r, "id"))
+	if err != nil {
+		writeJSON(w, http.StatusBadRequest, dtos.ErrorResponse{
+			Error: "invalid filament ID",
+			Code:  http.StatusBadRequest,
+		})
+		return
+	}
+
+	spool, err := h.service.GetByID(r.Context(), id)
+	if err != nil {
+		slog.Error("failed to get filament", "id", id, "error", err)
+		writeJSON(w, http.StatusInternalServerError, dtos.ErrorResponse{
+			Error: "internal server error",
+			Code:  http.StatusInternalServerError,
+		})
+		return
+	}
+	if spool == nil {
+		writeJSON(w, http.StatusNotFound, dtos.ErrorResponse{
+			Error: "filament not found",
+			Code:  http.StatusNotFound,
+		})
+		return
+	}
+
+	writeJSON(w, http.StatusOK, dtos.SingleResponse{Data: spool})
+}
+
+// Create handles POST /api/filaments — creates a new filament spool.
+func (h *FilamentHandler) Create(w http.ResponseWriter, r *http.Request) {
+	var req dtos.CreateFilamentRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeJSON(w, http.StatusBadRequest, dtos.ErrorResponse{
+			Error: "invalid request body",
+			Code:  http.StatusBadRequest,
+		})
+		return
+	}
+
+	// Validate required fields.
+	if err := services.ValidateCreateFilamentRequest(req); err != nil {
+		writeJSON(w, http.StatusBadRequest, dtos.ErrorResponse{
+			Error: "validation failed: " + err.Error(),
+			Code:  http.StatusBadRequest,
+		})
+		return
+	}
+
+	// Build domain model.
+	spool := models.FilamentSpool{
+		Name:                  req.Name,
+		MaterialBaseID:        req.MaterialBaseID,
+		MaterialFinishID:      req.MaterialFinishID,
+		MaterialModifierID:    req.MaterialModifierID,
+		ColorHex:             req.ColorHex,
+		Brand:                req.Brand,
+		DiameterMM:           1.75, // default
+		InitialGrams:         req.InitialGrams,
+		RemainingGrams:       req.RemainingGrams,
+		SpoolWeightGrams:     req.SpoolWeightGrams,
+		CostUSD:              req.CostUSD,
+		LowStockThresholdGrams: 50, // default
+		Notes:                req.Notes,
+		Barcode:              req.Barcode,
+	}
+	if req.DiameterMM != nil {
+		spool.DiameterMM = *req.DiameterMM
+	}
+	if req.LowStockThresholdGrams != nil {
+		spool.LowStockThresholdGrams = *req.LowStockThresholdGrams
+	}
+
+	created, err := h.service.Create(r.Context(), &spool)
+	if err != nil {
+		slog.Error("failed to create filament", "error", err)
+		writeJSON(w, http.StatusInternalServerError, dtos.ErrorResponse{
+			Error: "internal server error",
+			Code:  http.StatusInternalServerError,
+		})
+		return
+	}
+
+	writeJSON(w, http.StatusCreated, dtos.SingleResponse{Data: created})
+}
+
+// Update handles PUT /api/filaments/{id} — partially updates a spool.
+func (h *FilamentHandler) Update(w http.ResponseWriter, r *http.Request) {
+	id, err := strconv.Atoi(chi.URLParam(r, "id"))
+	if err != nil {
+		writeJSON(w, http.StatusBadRequest, dtos.ErrorResponse{
+			Error: "invalid filament ID",
+			Code:  http.StatusBadRequest,
+		})
+		return
+	}
+
+	var req dtos.UpdateFilamentRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeJSON(w, http.StatusBadRequest, dtos.ErrorResponse{
+			Error: "invalid request body",
+			Code:  http.StatusBadRequest,
+		})
+		return
+	}
+
+	// Validate update fields.
+	if err := services.ValidateUpdateFilamentRequest(req); err != nil {
+		writeJSON(w, http.StatusBadRequest, dtos.ErrorResponse{
+			Error: "validation failed: " + err.Error(),
+			Code:  http.StatusBadRequest,
+		})
+		return
+	}
+
+	// Build updates map (only non-nil fields).
+	updates := buildFilamentUpdates(req)
+
+	updated, err := h.service.Update(r.Context(), id, updates)
+	if err != nil {
+		slog.Error("failed to update filament", "id", id, "error", err)
+		writeJSON(w, http.StatusInternalServerError, dtos.ErrorResponse{
+			Error: "internal server error",
+			Code:  http.StatusInternalServerError,
+		})
+		return
+	}
+	if updated == nil {
+		writeJSON(w, http.StatusNotFound, dtos.ErrorResponse{
+			Error: "filament not found",
+			Code:  http.StatusNotFound,
+		})
+		return
+	}
+
+	writeJSON(w, http.StatusOK, dtos.SingleResponse{Data: updated})
+}
+
+// Delete handles DELETE /api/filaments/{id} — soft-deletes a spool.
+func (h *FilamentHandler) Delete(w http.ResponseWriter, r *http.Request) {
+	id, err := strconv.Atoi(chi.URLParam(r, "id"))
+	if err != nil {
+		writeJSON(w, http.StatusBadRequest, dtos.ErrorResponse{
+			Error: "invalid filament ID",
+			Code:  http.StatusBadRequest,
+		})
+		return
+	}
+
+	deleted, err := h.service.SoftDelete(r.Context(), id)
+	if err != nil {
+		slog.Error("failed to delete filament", "id", id, "error", err)
+		writeJSON(w, http.StatusInternalServerError, dtos.ErrorResponse{
+			Error: "internal server error",
+			Code:  http.StatusInternalServerError,
+		})
+		return
+	}
+	if !deleted {
+		writeJSON(w, http.StatusNotFound, dtos.ErrorResponse{
+			Error: "filament not found",
+			Code:  http.StatusNotFound,
+		})
+		return
+	}
+
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// buildFilamentUpdates converts an UpdateFilamentRequest to a map of column→value.
+func buildFilamentUpdates(req dtos.UpdateFilamentRequest) map[string]interface{} {
+	updates := make(map[string]interface{})
+	if req.Name != nil {
+		updates["name"] = *req.Name
+	}
+	if req.MaterialBaseID != nil {
+		updates["material_base_id"] = *req.MaterialBaseID
+	}
+	if req.MaterialFinishID != nil {
+		updates["material_finish_id"] = *req.MaterialFinishID
+	}
+	if req.MaterialModifierID != nil {
+		updates["material_modifier_id"] = *req.MaterialModifierID
+	}
+	if req.ColorHex != nil {
+		updates["color_hex"] = *req.ColorHex
+	}
+	if req.Brand != nil {
+		updates["brand"] = *req.Brand
+	}
+	if req.DiameterMM != nil {
+		updates["diameter_mm"] = *req.DiameterMM
+	}
+	if req.InitialGrams != nil {
+		updates["initial_grams"] = *req.InitialGrams
+	}
+	if req.RemainingGrams != nil {
+		updates["remaining_grams"] = *req.RemainingGrams
+	}
+	if req.SpoolWeightGrams != nil {
+		updates["spool_weight_grams"] = *req.SpoolWeightGrams
+	}
+	if req.CostUSD != nil {
+		updates["cost_usd"] = *req.CostUSD
+	}
+	if req.LowStockThresholdGrams != nil {
+		updates["low_stock_threshold_grams"] = *req.LowStockThresholdGrams
+	}
+	if req.Notes != nil {
+		updates["notes"] = *req.Notes
+	}
+	if req.Barcode != nil {
+		updates["barcode"] = *req.Barcode
+	}
+	return updates
+}

backend/internal/handlers/health.go

@@ -0,0 +1,50 @@
+package handlers
+
+import (
+	"context"
+	"encoding/json"
+	"log/slog"
+	"net/http"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// HealthHandler provides a health check endpoint that verifies database connectivity.
+type HealthHandler struct {
+	dbPool *pgxpool.Pool
+}
+
+// NewHealthHandler creates a new HealthHandler with the given database pool.
+func NewHealthHandler(dbPool *pgxpool.Pool) *HealthHandler {
+	return &HealthHandler{dbPool: dbPool}
+}
+
+// ServeHTTP handles GET /health requests.
+func (h *HealthHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
+	defer cancel()
+
+	dbConnected := false
+	if h.dbPool != nil {
+		if err := h.dbPool.Ping(ctx); err == nil {
+			dbConnected = true
+		} else {
+			slog.Warn("health check db ping failed", "error", err)
+		}
+	}
+
+	resp := map[string]any{
+		"status":       "ok",
+		"timestamp":    time.Now().UTC().Format(time.RFC3339),
+		"db_connected": dbConnected,
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	if !dbConnected {
+		w.WriteHeader(http.StatusServiceUnavailable)
+	}
+	if err := json.NewEncoder(w).Encode(resp); err != nil {
+		slog.Error("failed to encode health response", "error", err)
+	}
+}

backend/internal/handlers/helpers.go

@@ -0,0 +1,51 @@
+package handlers
+
+import (
+	"encoding/json"
+	"log/slog"
+	"net/http"
+	"strconv"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/dtos"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/services"
+)
+
+// writeJSON serializes v as JSON to the response writer with the given status code.
+// Logs an error if encoding fails.
+func writeJSON(w http.ResponseWriter, status int, v interface{}) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	if err := json.NewEncoder(w).Encode(v); err != nil {
+		slog.Error("failed to encode JSON response", "error", err)
+	}
+}
+
+// parsePagination reads limit and offset query parameters with defaults of 20 and 0.
+func parsePagination(r *http.Request) (limit, offset int) {
+	limit = 20
+	offset = 0
+
+	if l := r.URL.Query().Get("limit"); l != "" {
+		if parsed, err := strconv.Atoi(l); err == nil && parsed > 0 {
+			limit = parsed
+		}
+	}
+	if o := r.URL.Query().Get("offset"); o != "" {
+		if parsed, err := strconv.Atoi(o); err == nil && parsed >= 0 {
+			offset = parsed
+		}
+	}
+	return
+}
+
+// ValidateCreateFilamentRequest validates a CreateFilamentRequest DTO.
+// Re-exports the service-layer validator for handler use.
+func ValidateCreateFilamentRequest(req dtos.CreateFilamentRequest) error {
+	return services.ValidateCreateFilamentRequest(req)
+}
+
+// ValidateUpdateFilamentRequest validates an UpdateFilamentRequest DTO.
+// Re-exports the service-layer validator for handler use.
+func ValidateUpdateFilamentRequest(req dtos.UpdateFilamentRequest) error {
+	return services.ValidateUpdateFilamentRequest(req)
+}

backend/internal/handlers/material_handler.go

@@ -0,0 +1,34 @@
+package handlers
+
+import (
+	"log/slog"
+	"net/http"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/dtos"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/repositories"
+)
+
+// MaterialHandler handles requests for material lookup data.
+type MaterialHandler struct {
+	repo *repositories.MaterialRepository
+}
+
+// NewMaterialHandler creates a MaterialHandler with the given repository.
+func NewMaterialHandler(repo *repositories.MaterialRepository) *MaterialHandler {
+	return &MaterialHandler{repo: repo}
+}
+
+// List handles GET /api/materials — returns all material bases.
+func (h *MaterialHandler) List(w http.ResponseWriter, r *http.Request) {
+	materials, err := h.repo.GetAll(r.Context())
+	if err != nil {
+		slog.Error("failed to list materials", "error", err)
+		writeJSON(w, http.StatusInternalServerError, dtos.ErrorResponse{
+			Error: "internal server error",
+			Code:  http.StatusInternalServerError,
+		})
+		return
+	}
+
+	writeJSON(w, http.StatusOK, dtos.SingleResponse{Data: materials})
+}

backend/internal/handlers/print_job_handler.go

@@ -0,0 +1,60 @@
+package handlers
+
+import (
+	"log/slog"
+	"net/http"
+	"strconv"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/dtos"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/repositories"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/services"
+)
+
+// PrintJobHandler handles HTTP requests for print job operations.
+type PrintJobHandler struct {
+	service *services.PrintJobService
+}
+
+// NewPrintJobHandler creates a PrintJobHandler with the given service.
+func NewPrintJobHandler(service *services.PrintJobService) *PrintJobHandler {
+	return &PrintJobHandler{service: service}
+}
+
+// List handles GET /api/print-jobs — returns paginated, filtered print jobs.
+func (h *PrintJobHandler) List(w http.ResponseWriter, r *http.Request) {
+	limit, offset := parsePagination(r)
+	filter := repositories.PrintJobFilter{
+		Status: r.URL.Query().Get("status"),
+		Limit:  limit,
+		Offset: offset,
+	}
+
+	if pidStr := r.URL.Query().Get("printer_id"); pidStr != "" {
+		pid, err := strconv.Atoi(pidStr)
+		if err != nil {
+			writeJSON(w, http.StatusBadRequest, dtos.ErrorResponse{
+				Error: "invalid printer_id",
+				Code:  http.StatusBadRequest,
+			})
+			return
+		}
+		filter.PrinterID = &pid
+	}
+
+	jobs, total, err := h.service.List(r.Context(), filter)
+	if err != nil {
+		slog.Error("failed to list print jobs", "error", err)
+		writeJSON(w, http.StatusInternalServerError, dtos.ErrorResponse{
+			Error: "internal server error",
+			Code:  http.StatusInternalServerError,
+		})
+		return
+	}
+
+	writeJSON(w, http.StatusOK, dtos.ListResponse{
+		Data:   jobs,
+		Total:  total,
+		Limit:  limit,
+		Offset: offset,
+	})
+}

backend/internal/handlers/printer_handler.go

@@ -0,0 +1,34 @@
+package handlers
+
+import (
+	"log/slog"
+	"net/http"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/dtos"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/services"
+)
+
+// PrinterHandler handles HTTP requests for printer listings.
+type PrinterHandler struct {
+	service *services.PrinterService
+}
+
+// NewPrinterHandler creates a PrinterHandler with the given service.
+func NewPrinterHandler(service *services.PrinterService) *PrinterHandler {
+	return &PrinterHandler{service: service}
+}
+
+// List handles GET /api/printers — returns all printers with printer_type info.
+func (h *PrinterHandler) List(w http.ResponseWriter, r *http.Request) {
+	printers, err := h.service.List(r.Context())
+	if err != nil {
+		slog.Error("failed to list printers", "error", err)
+		writeJSON(w, http.StatusInternalServerError, dtos.ErrorResponse{
+			Error: "internal server error",
+			Code:  http.StatusInternalServerError,
+		})
+		return
+	}
+
+	writeJSON(w, http.StatusOK, dtos.SingleResponse{Data: printers})
+}

backend/internal/handlers/usage_log_handler.go

@@ -0,0 +1,70 @@
+package handlers
+
+import (
+	"log/slog"
+	"net/http"
+	"strconv"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/dtos"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/repositories"
+)
+
+// UsageLogHandler handles HTTP requests for usage log operations.
+type UsageLogHandler struct {
+	repo *repositories.UsageLogRepository
+}
+
+// NewUsageLogHandler creates a UsageLogHandler with the given repository.
+func NewUsageLogHandler(repo *repositories.UsageLogRepository) *UsageLogHandler {
+	return &UsageLogHandler{repo: repo}
+}
+
+// List handles GET /api/usage-logs — returns paginated, filtered usage logs.
+func (h *UsageLogHandler) List(w http.ResponseWriter, r *http.Request) {
+	limit, offset := parsePagination(r)
+	filter := repositories.UsageLogFilter{
+		Limit:  limit,
+		Offset: offset,
+	}
+
+	if sidStr := r.URL.Query().Get("spool_id"); sidStr != "" {
+		sid, err := strconv.Atoi(sidStr)
+		if err != nil {
+			writeJSON(w, http.StatusBadRequest, dtos.ErrorResponse{
+				Error: "invalid spool_id",
+				Code:  http.StatusBadRequest,
+			})
+			return
+		}
+		filter.SpoolID = &sid
+	}
+
+	if jidStr := r.URL.Query().Get("job_id"); jidStr != "" {
+		jid, err := strconv.Atoi(jidStr)
+		if err != nil {
+			writeJSON(w, http.StatusBadRequest, dtos.ErrorResponse{
+				Error: "invalid job_id",
+				Code:  http.StatusBadRequest,
+			})
+			return
+		}
+		filter.JobID = &jid
+	}
+
+	logs, total, err := h.repo.GetAll(r.Context(), filter)
+	if err != nil {
+		slog.Error("failed to list usage logs", "error", err)
+		writeJSON(w, http.StatusInternalServerError, dtos.ErrorResponse{
+			Error: "internal server error",
+			Code:  http.StatusInternalServerError,
+		})
+		return
+	}
+
+	writeJSON(w, http.StatusOK, dtos.ListResponse{
+		Data:   logs,
+		Total:  total,
+		Limit:  limit,
+		Offset: offset,
+	})
+}

backend/internal/models/models.go

@@ -0,0 +1,162 @@
+// Package models defines the Extrudex domain model structs.
+// These map 1:1 to PostgreSQL tables with snake_case JSON serialization.
+// Nullable fields use pointer types; all timestamps are time.Time.
+package models
+
+import "time"
+
+// ============================================================================
+// Lookup Tables
+// ============================================================================
+
+// PrinterType represents a printer technology category (fdm, resin, etc.).
+type PrinterType struct {
+	ID        int       `json:"id"`
+	Name      string    `json:"name"`
+	CreatedAt time.Time `json:"created_at"`
+	UpdatedAt time.Time `json:"updated_at"`
+}
+
+// JobStatus represents a print job lifecycle state.
+type JobStatus struct {
+	ID        int       `json:"id"`
+	Name      string    `json:"name"`
+	CreatedAt time.Time `json:"created_at"`
+	UpdatedAt time.Time `json:"updated_at"`
+}
+
+// MaterialBase represents a base material type (PLA, PETG, ABS, etc.).
+// Density and temperature ranges are stored here for grams-calculation and slicing guidance.
+type MaterialBase struct {
+	ID               int        `json:"id"`
+	Name             string     `json:"name"`
+	DensityGCm3      float64    `json:"density_g_cm3"`
+	ExtrusionTempMin *int       `json:"extrusion_temp_min,omitempty"`
+	ExtrusionTempMax *int       `json:"extrusion_temp_max,omitempty"`
+	BedTempMin       *int       `json:"bed_temp_min,omitempty"`
+	BedTempMax       *int       `json:"bed_temp_max,omitempty"`
+	CreatedAt        time.Time  `json:"created_at"`
+	UpdatedAt        time.Time  `json:"updated_at"`
+}
+
+// MaterialFinish represents the visual/texture finish (Basic, Silk, Matte, etc.).
+type MaterialFinish struct {
+	ID          int       `json:"id"`
+	Name        string    `json:"name"`
+	Description *string   `json:"description,omitempty"`
+	CreatedAt   time.Time `json:"created_at"`
+	UpdatedAt   time.Time `json:"updated_at"`
+}
+
+// MaterialModifier represents an additive property (Carbon Fiber, Wood-Filled, etc.).
+type MaterialModifier struct {
+	ID          int       `json:"id"`
+	Name        string    `json:"name"`
+	Description *string   `json:"description,omitempty"`
+	CreatedAt   time.Time `json:"created_at"`
+	UpdatedAt   time.Time `json:"updated_at"`
+}
+
+// ============================================================================
+// Core Entity Tables
+// ============================================================================
+
+// Printer represents a 3D printer in the fleet.
+type Printer struct {
+	ID              int        `json:"id"`
+	Name            string     `json:"name"`
+	PrinterTypeID   int        `json:"printer_type_id"`
+	PrinterType     *PrinterType `json:"printer_type,omitempty"` // populated on JOIN queries
+	Manufacturer    *string    `json:"manufacturer,omitempty"`
+	Model           *string    `json:"model,omitempty"`
+	MoonrakerURL    *string    `json:"moonraker_url,omitempty"`
+	MoonrakerAPIKey *string    `json:"moonraker_api_key,omitempty"`
+	MQTTBrokerHost  *string    `json:"mqtt_broker_host,omitempty"`
+	MQTTTopicPrefix *string    `json:"mqtt_topic_prefix,omitempty"`
+	MQTTTLSEnabled  bool       `json:"mqtt_tls_enabled"`
+	IsActive        bool       `json:"is_active"`
+	CreatedAt       time.Time  `json:"created_at"`
+	UpdatedAt       time.Time  `json:"updated_at"`
+}
+
+// FilamentSpool represents a physical filament spool in inventory.
+// material_finish_id defaults to 1 ("Basic"); material_modifier_id is optional.
+// Grams are always physically measured values — grams_used is derived, not stored.
+type FilamentSpool struct {
+	ID                    int             `json:"id"`
+	Name                  string          `json:"name"`
+	MaterialBaseID        int             `json:"material_base_id"`
+	MaterialBase          *MaterialBase   `json:"material_base,omitempty"`   // JOIN
+	MaterialFinishID      int             `json:"material_finish_id"`
+	MaterialFinish        *MaterialFinish `json:"material_finish,omitempty"` // JOIN
+	MaterialModifierID    *int            `json:"material_modifier_id,omitempty"`
+	MaterialModifier      *MaterialModifier `json:"material_modifier,omitempty"` // JOIN
+	ColorHex              string          `json:"color_hex"`
+	Brand                 *string         `json:"brand,omitempty"`
+	DiameterMM            float64         `json:"diameter_mm"`
+	InitialGrams          int             `json:"initial_grams"`
+	RemainingGrams        int             `json:"remaining_grams"`
+	SpoolWeightGrams      *int            `json:"spool_weight_grams,omitempty"`
+	CostUSD               *float64        `json:"cost_usd,omitempty"`
+	LowStockThresholdGrams int            `json:"low_stock_threshold_grams"`
+	Notes                 *string         `json:"notes,omitempty"`
+	Barcode               *string         `json:"barcode,omitempty"`
+	DeletedAt             *time.Time      `json:"deleted_at,omitempty"`
+	CreatedAt             time.Time       `json:"created_at"`
+	UpdatedAt             time.Time       `json:"updated_at"`
+}
+
+// PrintJob represents a single print on a specific printer.
+// The filament_spool_id is a convenience reference; multi-spool jobs track usage in usage_logs.
+type PrintJob struct {
+	ID                      int         `json:"id"`
+	PrinterID               int         `json:"printer_id"`
+	Printer                 *Printer    `json:"printer,omitempty"`      // JOIN
+	FilamentSpoolID         *int        `json:"filament_spool_id,omitempty"`
+	FilamentSpool           *FilamentSpool `json:"filament_spool,omitempty"` // JOIN
+	JobName                 string      `json:"job_name"`
+	FileName                *string     `json:"file_name,omitempty"`
+	JobStatusID             int         `json:"job_status_id"`
+	JobStatus               *JobStatus  `json:"job_status,omitempty"`  // JOIN
+	StartedAt               *time.Time  `json:"started_at,omitempty"`
+	CompletedAt             *time.Time  `json:"completed_at,omitempty"`
+	DurationSeconds         *int        `json:"duration_seconds,omitempty"`
+	EstimatedDurationSeconds *int       `json:"estimated_duration_seconds,omitempty"`
+	TotalMMExtruded         *float64    `json:"total_mm_extruded,omitempty"`
+	TotalGramsUsed          *float64    `json:"total_grams_used,omitempty"`
+	TotalCostUSD            *float64    `json:"total_cost_usd,omitempty"`
+	Notes                   *string     `json:"notes,omitempty"`
+	DeletedAt               *time.Time  `json:"deleted_at,omitempty"`
+	CreatedAt               time.Time   `json:"created_at"`
+	UpdatedAt               time.Time   `json:"updated_at"`
+}
+
+// UsageLog records filament consumption for a specific spool during a print job.
+// This is the atomic unit of filament tracking — grams are derived from mm_extruded.
+type UsageLog struct {
+	ID              int            `json:"id"`
+	PrintJobID      int            `json:"print_job_id"`
+	PrintJob        *PrintJob      `json:"print_job,omitempty"`        // JOIN
+	FilamentSpoolID int            `json:"filament_spool_id"`
+	FilamentSpool   *FilamentSpool `json:"filament_spool,omitempty"`   // JOIN
+	MMExtruded      float64        `json:"mm_extruded"`
+	GramsUsed       float64        `json:"grams_used"`
+	CostUSD         *float64       `json:"cost_usd,omitempty"`
+	LoggedAt        time.Time      `json:"logged_at"`
+	CreatedAt       time.Time      `json:"created_at"`
+}
+
+// ============================================================================
+// Application Settings
+// ============================================================================
+
+// Setting represents a key-value application configuration entry.
+// The value is stored as JSONB in PostgreSQL, allowing flexible typed config.
+type Setting struct {
+	ID          int       `json:"id"`
+	Key         string    `json:"key"`
+	Value       []byte    `json:"value"`  // raw JSON — marshalled/unmarshalled by caller
+	Description *string   `json:"description,omitempty"`
+	CreatedAt   time.Time `json:"created_at"`
+	UpdatedAt   time.Time `json:"updated_at"`
+}

backend/internal/repositories/filament_repository.go

@@ -0,0 +1,285 @@
+package repositories
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/models"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// FilamentRepository handles database queries for filament_spools.
+type FilamentRepository struct {
+	pool *pgxpool.Pool
+}
+
+// NewFilamentRepository creates a FilamentRepository backed by the given pool.
+func NewFilamentRepository(pool *pgxpool.Pool) *FilamentRepository {
+	return &FilamentRepository{pool: pool}
+}
+
+// FilamentFilter holds query parameters for listing filament spools.
+type FilamentFilter struct {
+	Material string // filter by material_base name (case-insensitive)
+	Finish   string // filter by material_finish name (case-insensitive)
+	Color    string // filter by exact color_hex match
+	LowStock bool   // if true, filter for remaining_grams <= low_stock_threshold_grams
+	Limit    int
+	Offset   int
+}
+
+// spoolScanFields is the common SELECT column list for filament spools with JOINs.
+const spoolScanFields = `
+	s.id, s.name,
+	s.material_base_id,
+	COALESCE(mb.name, '') as material_base_name,
+	COALESCE(mb.density_g_cm3, 0) as material_base_density_g_cm3,
+	COALESCE(mb.extrusion_temp_min, NULL::int) as material_base_extrusion_temp_min,
+	COALESCE(mb.extrusion_temp_max, NULL::int) as material_base_extrusion_temp_max,
+	COALESCE(mb.bed_temp_min, NULL::int) as material_base_bed_temp_min,
+	COALESCE(mb.bed_temp_max, NULL::int) as material_base_bed_temp_max,
+	COALESCE(mb.created_at, s.created_at) as material_base_created_at,
+	COALESCE(mb.updated_at, s.created_at) as material_base_updated_at,
+	s.material_finish_id,
+	COALESCE(mf.name, '') as material_finish_name,
+	mf.description as material_finish_description,
+	COALESCE(mf.created_at, s.created_at) as material_finish_created_at,
+	COALESCE(mf.updated_at, s.created_at) as material_finish_updated_at,
+	s.material_modifier_id,
+	mm.name as material_modifier_name,
+	mm.description as material_modifier_description,
+	mm.created_at as material_modifier_created_at,
+	mm.updated_at as material_modifier_updated_at,
+	s.color_hex, s.brand, s.diameter_mm,
+	s.initial_grams, s.remaining_grams, s.spool_weight_grams,
+	s.cost_usd, s.low_stock_threshold_grams,
+	s.notes, s.barcode,
+	s.deleted_at, s.created_at, s.updated_at`
+
+const spoolFromJoins = `
+	FROM filament_spools s
+	LEFT JOIN material_bases mb ON s.material_base_id = mb.id
+	LEFT JOIN material_finishes mf ON s.material_finish_id = mf.id
+	LEFT JOIN material_modifiers mm ON s.material_modifier_id = mm.id`
+
+// scanSpoolWithJoins scans a full spool row including all JOINed tables.
+func scanSpoolWithJoins(row interface{ Scan(...interface{}) error }) (models.FilamentSpool, error) {
+	var s models.FilamentSpool
+	var mb models.MaterialBase
+	var mf models.MaterialFinish
+	var mfDesc *string
+	var modifierID *int
+	var modName, modDesc *string
+	var modCreatedAt, modUpdatedAt *time.Time
+
+	err := row.Scan(
+		&s.ID, &s.Name,
+		&s.MaterialBaseID,
+		&mb.Name, &mb.DensityGCm3,
+		&mb.ExtrusionTempMin, &mb.ExtrusionTempMax,
+		&mb.BedTempMin, &mb.BedTempMax,
+		&mb.CreatedAt, &mb.UpdatedAt,
+		&s.MaterialFinishID,
+		&mf.Name, &mfDesc,
+		&mf.CreatedAt, &mf.UpdatedAt,
+		&modifierID,
+		&modName, &modDesc,
+		&modCreatedAt, &modUpdatedAt,
+		&s.ColorHex, &s.Brand, &s.DiameterMM,
+		&s.InitialGrams, &s.RemainingGrams, &s.SpoolWeightGrams,
+		&s.CostUSD, &s.LowStockThresholdGrams,
+		&s.Notes, &s.Barcode,
+		&s.DeletedAt, &s.CreatedAt, &s.UpdatedAt,
+	)
+	if err != nil {
+		return s, err
+	}
+
+	mb.ID = s.MaterialBaseID
+	s.MaterialBase = &mb
+
+	mf.ID = s.MaterialFinishID
+	if mfDesc != nil {
+		mf.Description = mfDesc
+	}
+	s.MaterialFinish = &mf
+
+	s.MaterialModifierID = modifierID
+	if modifierID != nil && modName != nil {
+		mm := models.MaterialModifier{
+			ID:   *modifierID,
+			Name: *modName,
+		}
+		if modDesc != nil {
+			mm.Description = modDesc
+		}
+		if modCreatedAt != nil {
+			mm.CreatedAt = *modCreatedAt
+		}
+		if modUpdatedAt != nil {
+			mm.UpdatedAt = *modUpdatedAt
+		}
+		s.MaterialModifier = &mm
+	}
+
+	return s, nil
+}
+
+// GetAll returns filament spools matching the given filters, with pagination.
+// Returns results, total matching count, and any error.
+func (r *FilamentRepository) GetAll(ctx context.Context, filter FilamentFilter) ([]models.FilamentSpool, int, error) {
+	conditions := []string{"s.deleted_at IS NULL"}
+	args := []interface{}{}
+	argIdx := 1
+
+	if filter.Material != "" {
+		conditions = append(conditions, fmt.Sprintf("LOWER(mb.name) = LOWER($%d)", argIdx))
+		args = append(args, filter.Material)
+		argIdx++
+	}
+	if filter.Finish != "" {
+		conditions = append(conditions, fmt.Sprintf("LOWER(mf.name) = LOWER($%d)", argIdx))
+		args = append(args, filter.Finish)
+		argIdx++
+	}
+	if filter.Color != "" {
+		conditions = append(conditions, fmt.Sprintf("s.color_hex = $%d", argIdx))
+		args = append(args, filter.Color)
+		argIdx++
+	}
+	if filter.LowStock {
+		conditions = append(conditions, "s.remaining_grams <= s.low_stock_threshold_grams")
+	}
+
+	whereClause := ""
+	if len(conditions) > 0 {
+		whereClause = "WHERE " + strings.Join(conditions, " AND ")
+	}
+
+	// Count total.
+	var total int
+	countQuery := "SELECT COUNT(*) " + spoolFromJoins + " " + whereClause
+	if err := r.pool.QueryRow(ctx, countQuery, args...).Scan(&total); err != nil {
+		return nil, 0, err
+	}
+
+	// Query with pagination.
+	dataQuery := "SELECT " + spoolScanFields + " " + spoolFromJoins + " " +
+		whereClause +
+		" ORDER BY s.name ASC" +
+		fmt.Sprintf(" LIMIT $%d OFFSET $%d", argIdx, argIdx+1)
+
+	dataArgs := make([]interface{}, len(args))
+	copy(dataArgs, args)
+	dataArgs = append(dataArgs, filter.Limit, filter.Offset)
+
+	rows, err := r.pool.Query(ctx, dataQuery, dataArgs...)
+	if err != nil {
+		return nil, 0, err
+	}
+	defer rows.Close()
+
+	var spools []models.FilamentSpool
+	for rows.Next() {
+		s, err := scanSpoolWithJoins(rows)
+		if err != nil {
+			return nil, 0, err
+		}
+		spools = append(spools, s)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, 0, err
+	}
+	if spools == nil {
+		spools = []models.FilamentSpool{}
+	}
+
+	return spools, total, nil
+}
+
+// GetByID returns a single filament spool by ID with JOINed data.
+// Returns nil if not found or soft-deleted.
+func (r *FilamentRepository) GetByID(ctx context.Context, id int) (*models.FilamentSpool, error) {
+	query := "SELECT " + spoolScanFields + " " + spoolFromJoins +
+		" WHERE s.id = $1 AND s.deleted_at IS NULL"
+
+	row := r.pool.QueryRow(ctx, query, id)
+	s, err := scanSpoolWithJoins(row)
+	if err != nil {
+		return nil, err
+	}
+	return &s, nil
+}
+
+// Create inserts a new filament spool and returns the created spool with JOINed data.
+func (r *FilamentRepository) Create(ctx context.Context, spool *models.FilamentSpool) (*models.FilamentSpool, error) {
+	var id int
+	err := r.pool.QueryRow(ctx, `
+		INSERT INTO filament_spools (
+			name, material_base_id, material_finish_id, material_modifier_id,
+			color_hex, brand, diameter_mm, initial_grams, remaining_grams,
+			spool_weight_grams, cost_usd, low_stock_threshold_grams,
+			notes, barcode
+		) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14)
+		RETURNING id
+	`,
+		spool.Name, spool.MaterialBaseID, spool.MaterialFinishID, spool.MaterialModifierID,
+		spool.ColorHex, spool.Brand, spool.DiameterMM, spool.InitialGrams, spool.RemainingGrams,
+		spool.SpoolWeightGrams, spool.CostUSD, spool.LowStockThresholdGrams,
+		spool.Notes, spool.Barcode,
+	).Scan(&id)
+	if err != nil {
+		return nil, err
+	}
+
+	return r.GetByID(ctx, id)
+}
+
+// Update applies partial updates to an existing filament spool.
+// Only non-nil fields in the update map are applied.
+// Returns the updated spool.
+func (r *FilamentRepository) Update(ctx context.Context, id int, updates map[string]interface{}) (*models.FilamentSpool, error) {
+	if len(updates) == 0 {
+		return r.GetByID(ctx, id)
+	}
+
+	setClauses := []string{"updated_at = NOW()"}
+	args := []interface{}{}
+	argIdx := 1
+
+	for col, val := range updates {
+		setClauses = append(setClauses, fmt.Sprintf("%s = $%d", col, argIdx))
+		args = append(args, val)
+		argIdx++
+	}
+
+	args = append(args, id)
+	query := fmt.Sprintf("UPDATE filament_spools SET %s WHERE id = $%d AND deleted_at IS NULL",
+		strings.Join(setClauses, ", "), argIdx)
+
+	result, err := r.pool.Exec(ctx, query, args...)
+	if err != nil {
+		return nil, err
+	}
+	if result.RowsAffected() == 0 {
+		return nil, nil // not found or deleted
+	}
+
+	return r.GetByID(ctx, id)
+}
+
+// SoftDelete marks a filament spool as deleted by setting deleted_at = NOW().
+// Returns true if a row was affected.
+func (r *FilamentRepository) SoftDelete(ctx context.Context, id int) (bool, error) {
+	result, err := r.pool.Exec(ctx, `
+		UPDATE filament_spools
+		SET deleted_at = NOW(), updated_at = NOW()
+		WHERE id = $1 AND deleted_at IS NULL
+	`, id)
+	if err != nil {
+		return false, err
+	}
+	return result.RowsAffected() > 0, nil
+}

backend/internal/repositories/material_repository.go

@@ -0,0 +1,54 @@
+// Package repositories provides data access logic backed by PostgreSQL via pgxpool.
+package repositories
+
+import (
+	"context"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/models"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// MaterialRepository handles database queries for material lookup tables.
+type MaterialRepository struct {
+	pool *pgxpool.Pool
+}
+
+// NewMaterialRepository creates a MaterialRepository backed by the given pool.
+func NewMaterialRepository(pool *pgxpool.Pool) *MaterialRepository {
+	return &MaterialRepository{pool: pool}
+}
+
+// GetAll returns all material bases ordered by name.
+func (r *MaterialRepository) GetAll(ctx context.Context) ([]models.MaterialBase, error) {
+	rows, err := r.pool.Query(ctx, `
+		SELECT id, name, density_g_cm3, extrusion_temp_min, extrusion_temp_max,
+		       bed_temp_min, bed_temp_max, created_at, updated_at
+		FROM material_bases
+		ORDER BY name
+	`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var materials []models.MaterialBase
+	for rows.Next() {
+		var m models.MaterialBase
+		if err := rows.Scan(
+			&m.ID, &m.Name, &m.DensityGCm3,
+			&m.ExtrusionTempMin, &m.ExtrusionTempMax,
+			&m.BedTempMin, &m.BedTempMax,
+			&m.CreatedAt, &m.UpdatedAt,
+		); err != nil {
+			return nil, err
+		}
+		materials = append(materials, m)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	if materials == nil {
+		materials = []models.MaterialBase{}
+	}
+	return materials, nil
+}

backend/internal/repositories/print_job_repository.go

@@ -0,0 +1,157 @@
+package repositories
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/models"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// PrintJobRepository handles database queries for print_jobs.
+type PrintJobRepository struct {
+	pool *pgxpool.Pool
+}
+
+// NewPrintJobRepository creates a PrintJobRepository backed by the given pool.
+func NewPrintJobRepository(pool *pgxpool.Pool) *PrintJobRepository {
+	return &PrintJobRepository{pool: pool}
+}
+
+// PrintJobFilter holds query parameters for listing print jobs.
+type PrintJobFilter struct {
+	Status    string // filter by job_status name (case-insensitive)
+	PrinterID *int   // filter by printer_id
+	Limit     int
+	Offset    int
+}
+
+// scanPrintJobWithJoins scans a print_job row with JOINed tables.
+func (r *PrintJobRepository) scanPrintJobWithJoins(row interface{ Scan(...interface{}) error }) (models.PrintJob, error) {
+	var pj models.PrintJob
+	var js models.JobStatus
+
+	err := row.Scan(
+		&pj.ID, &pj.PrinterID, &pj.FilamentSpoolID,
+		&pj.JobName, &pj.FileName,
+		&pj.JobStatusID,
+		&pj.StartedAt, &pj.CompletedAt,
+		&pj.DurationSeconds, &pj.EstimatedDurationSeconds,
+		&pj.TotalMMExtruded, &pj.TotalGramsUsed, &pj.TotalCostUSD,
+		&pj.Notes,
+		&pj.DeletedAt, &pj.CreatedAt, &pj.UpdatedAt,
+		&js.ID, &js.Name,
+		&js.CreatedAt, &js.UpdatedAt,
+	)
+	if err != nil {
+		return pj, err
+	}
+
+	pj.JobStatus = &js
+	return pj, nil
+}
+
+// GetAll returns print jobs matching the given filters, with pagination.
+func (r *PrintJobRepository) GetAll(ctx context.Context, filter PrintJobFilter) ([]models.PrintJob, int, error) {
+	conditions := []string{"pj.deleted_at IS NULL"}
+	args := []interface{}{}
+	argIdx := 1
+
+	if filter.Status != "" {
+		conditions = append(conditions, fmt.Sprintf("LOWER(js.name) = LOWER($%d)", argIdx))
+		args = append(args, filter.Status)
+		argIdx++
+	}
+	if filter.PrinterID != nil {
+		conditions = append(conditions, fmt.Sprintf("pj.printer_id = $%d", argIdx))
+		args = append(args, *filter.PrinterID)
+		argIdx++
+	}
+
+	whereClause := ""
+	if len(conditions) > 0 {
+		whereClause = "WHERE " + strings.Join(conditions, " AND ")
+	}
+
+	// Count.
+	var total int
+	countQuery := `SELECT COUNT(*)
+		FROM print_jobs pj
+		LEFT JOIN job_statuses js ON pj.job_status_id = js.id
+	` + " " + whereClause
+	if err := r.pool.QueryRow(ctx, countQuery, args...).Scan(&total); err != nil {
+		return nil, 0, err
+	}
+
+	// Query with pagination.
+	dataQuery := `SELECT
+		pj.id, pj.printer_id, pj.filament_spool_id,
+		pj.job_name, pj.file_name,
+		pj.job_status_id,
+		pj.started_at, pj.completed_at,
+		pj.duration_seconds, pj.estimated_duration_seconds,
+		pj.total_mm_extruded, pj.total_grams_used, pj.total_cost_usd,
+		pj.notes,
+		pj.deleted_at, pj.created_at, pj.updated_at,
+		js.id, js.name,
+		js.created_at, js.updated_at
+	FROM print_jobs pj
+	LEFT JOIN job_statuses js ON pj.job_status_id = js.id
+	` + whereClause +
+		" ORDER BY pj.created_at DESC" +
+		fmt.Sprintf(" LIMIT $%d OFFSET $%d", argIdx, argIdx+1)
+
+	dataArgs := make([]interface{}, len(args))
+	copy(dataArgs, args)
+	dataArgs = append(dataArgs, filter.Limit, filter.Offset)
+
+	rows, err := r.pool.Query(ctx, dataQuery, dataArgs...)
+	if err != nil {
+		return nil, 0, err
+	}
+	defer rows.Close()
+
+	var jobs []models.PrintJob
+	for rows.Next() {
+		pj, err := r.scanPrintJobWithJoins(rows)
+		if err != nil {
+			return nil, 0, err
+		}
+		jobs = append(jobs, pj)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, 0, err
+	}
+	if jobs == nil {
+		jobs = []models.PrintJob{}
+	}
+
+	return jobs, total, nil
+}
+
+// GetByID returns a single print job by ID with JOINed job_status.
+func (r *PrintJobRepository) GetByID(ctx context.Context, id int) (*models.PrintJob, error) {
+	row := r.pool.QueryRow(ctx, `
+		SELECT
+			pj.id, pj.printer_id, pj.filament_spool_id,
+			pj.job_name, pj.file_name,
+			pj.job_status_id,
+			pj.started_at, pj.completed_at,
+			pj.duration_seconds, pj.estimated_duration_seconds,
+			pj.total_mm_extruded, pj.total_grams_used, pj.total_cost_usd,
+			pj.notes,
+			pj.deleted_at, pj.created_at, pj.updated_at,
+			js.id, js.name,
+			js.created_at, js.updated_at
+		FROM print_jobs pj
+		LEFT JOIN job_statuses js ON pj.job_status_id = js.id
+		WHERE pj.id = $1 AND pj.deleted_at IS NULL
+	`, id)
+
+	pj, err := r.scanPrintJobWithJoins(row)
+	if err != nil {
+		return nil, err
+	}
+	return &pj, nil
+}

backend/internal/repositories/printer_repository.go

@@ -0,0 +1,78 @@
+package repositories
+
+import (
+	"context"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/models"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// PrinterRepository handles database queries for printers.
+type PrinterRepository struct {
+	pool *pgxpool.Pool
+}
+
+// NewPrinterRepository creates a PrinterRepository backed by the given pool.
+func NewPrinterRepository(pool *pgxpool.Pool) *PrinterRepository {
+	return &PrinterRepository{pool: pool}
+}
+
+// scanPrinterWithType scans a printer row with JOINed printer_type.
+func (r *PrinterRepository) scanPrinterWithType(row interface{ Scan(...interface{}) error }) (models.Printer, error) {
+	var p models.Printer
+	var pt models.PrinterType
+
+	err := row.Scan(
+		&p.ID, &p.Name, &p.PrinterTypeID,
+		&p.Manufacturer, &p.Model,
+		&p.MoonrakerURL, &p.MoonrakerAPIKey,
+		&p.MQTTBrokerHost, &p.MQTTTopicPrefix,
+		&p.MQTTTLSEnabled, &p.IsActive,
+		&p.CreatedAt, &p.UpdatedAt,
+		&pt.ID, &pt.Name,
+		&pt.CreatedAt, &pt.UpdatedAt,
+	)
+	if err != nil {
+		return p, err
+	}
+
+	p.PrinterType = &pt
+	return p, nil
+}
+
+// GetAll returns all printers joined with their printer_type, ordered by name.
+func (r *PrinterRepository) GetAll(ctx context.Context) ([]models.Printer, error) {
+	rows, err := r.pool.Query(ctx, `
+		SELECT p.id, p.name, p.printer_type_id,
+		       p.manufacturer, p.model,
+		       p.moonraker_url, p.moonraker_api_key,
+		       p.mqtt_broker_host, p.mqtt_topic_prefix,
+		       p.mqtt_tls_enabled, p.is_active,
+		       p.created_at, p.updated_at,
+		       pt.id, pt.name,
+		       pt.created_at, pt.updated_at
+		FROM printers p
+		JOIN printer_types pt ON p.printer_type_id = pt.id
+		ORDER BY p.name
+	`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var printers []models.Printer
+	for rows.Next() {
+		p, err := r.scanPrinterWithType(rows)
+		if err != nil {
+			return nil, err
+		}
+		printers = append(printers, p)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	if printers == nil {
+		printers = []models.Printer{}
+	}
+	return printers, nil
+}

backend/internal/repositories/usage_log_repository.go

@@ -0,0 +1,96 @@
+package repositories
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/models"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// UsageLogRepository handles database queries for usage_logs.
+type UsageLogRepository struct {
+	pool *pgxpool.Pool
+}
+
+// NewUsageLogRepository creates a UsageLogRepository backed by the given pool.
+func NewUsageLogRepository(pool *pgxpool.Pool) *UsageLogRepository {
+	return &UsageLogRepository{pool: pool}
+}
+
+// UsageLogFilter holds query parameters for listing usage logs.
+type UsageLogFilter struct {
+	SpoolID *int // filter by filament_spool_id
+	JobID   *int // filter by print_job_id
+	Limit   int
+	Offset  int
+}
+
+// GetAll returns usage logs matching the given filters, with pagination.
+func (r *UsageLogRepository) GetAll(ctx context.Context, filter UsageLogFilter) ([]models.UsageLog, int, error) {
+	conditions := []string{"1=1"}
+	args := []interface{}{}
+	argIdx := 1
+
+	if filter.SpoolID != nil {
+		conditions = append(conditions, fmt.Sprintf("ul.filament_spool_id = $%d", argIdx))
+		args = append(args, *filter.SpoolID)
+		argIdx++
+	}
+	if filter.JobID != nil {
+		conditions = append(conditions, fmt.Sprintf("ul.print_job_id = $%d", argIdx))
+		args = append(args, *filter.JobID)
+		argIdx++
+	}
+
+	whereClause := "WHERE " + fmt.Sprintf("%s", conditions[0])
+	for _, c := range conditions[1:] {
+		whereClause += " AND " + c
+	}
+
+	// Count.
+	var total int
+	countQuery := "SELECT COUNT(*) FROM usage_logs ul " + whereClause
+	if err := r.pool.QueryRow(ctx, countQuery, args...).Scan(&total); err != nil {
+		return nil, 0, err
+	}
+
+	// Query with pagination.
+	dataQuery := `SELECT id, print_job_id, filament_spool_id, mm_extruded,
+	       grams_used, cost_usd, logged_at, created_at
+	FROM usage_logs ul
+	` + whereClause +
+		" ORDER BY ul.logged_at DESC" +
+		fmt.Sprintf(" LIMIT $%d OFFSET $%d", argIdx, argIdx+1)
+
+	dataArgs := make([]interface{}, len(args))
+	copy(dataArgs, args)
+	dataArgs = append(dataArgs, filter.Limit, filter.Offset)
+
+	rows, err := r.pool.Query(ctx, dataQuery, dataArgs...)
+	if err != nil {
+		return nil, 0, err
+	}
+	defer rows.Close()
+
+	var logs []models.UsageLog
+	for rows.Next() {
+		var l models.UsageLog
+		if err := rows.Scan(
+			&l.ID, &l.PrintJobID, &l.FilamentSpoolID,
+			&l.MMExtruded, &l.GramsUsed, &l.CostUSD,
+			&l.LoggedAt, &l.CreatedAt,
+		); err != nil {
+			return nil, 0, err
+		}
+		logs = append(logs, l)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, 0, err
+	}
+	if logs == nil {
+		logs = []models.UsageLog{}
+	}
+
+	return logs, total, nil
+}

backend/internal/router/router.go

@@ -0,0 +1,90 @@
+package router
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/config"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/handlers"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/repositories"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/services"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/sse"
+	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// New creates and configures a Chi router with all middleware and handlers mounted.
+func New(cfg *config.Config, dbPool *pgxpool.Pool, sseBC *sse.Broadcaster) chi.Router {
+	r := chi.NewRouter()
+
+	// Middleware
+	r.Use(middleware.RequestID)
+	r.Use(middleware.RealIP)
+	r.Use(middleware.Logger)
+	r.Use(middleware.Recoverer)
+	// Timeout middleware is applied per-route below to exclude SSE
+
+	// CORS
+	r.Use(func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Access-Control-Allow-Origin", cfg.CorsOrigin)
+			w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
+			w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
+			if r.Method == http.MethodOptions {
+				w.WriteHeader(http.StatusNoContent)
+				return
+			}
+			next.ServeHTTP(w, r)
+		})
+	})
+
+	// Health check (with timeout)
+	healthHandler := handlers.NewHealthHandler(dbPool)
+	r.With(middleware.Timeout(30 * time.Second)).Get("/health", healthHandler.ServeHTTP)
+
+	// ── Repositories ──────────────────────────────────────────────────────
+	materialRepo := repositories.NewMaterialRepository(dbPool)
+	filamentRepo := repositories.NewFilamentRepository(dbPool)
+	printerRepo := repositories.NewPrinterRepository(dbPool)
+	printJobRepo := repositories.NewPrintJobRepository(dbPool)
+	usageLogRepo := repositories.NewUsageLogRepository(dbPool)
+
+	// ── Services ──────────────────────────────────────────────────────────
+	filamentService := services.NewFilamentService(filamentRepo)
+	printerService := services.NewPrinterService(printerRepo)
+	printJobService := services.NewPrintJobService(printJobRepo)
+
+	// ── Handlers ──────────────────────────────────────────────────────────
+	materialHandler := handlers.NewMaterialHandler(materialRepo)
+	filamentHandler := handlers.NewFilamentHandler(filamentService)
+	printerHandler := handlers.NewPrinterHandler(printerService)
+	printJobHandler := handlers.NewPrintJobHandler(printJobService)
+	usageLogHandler := handlers.NewUsageLogHandler(usageLogRepo)
+
+	// ── API Routes (with timeout) ─────────────────────────────────────────
+	r.Route("/api", func(r chi.Router) {
+		r.Use(middleware.Timeout(60 * time.Second))
+		r.Get("/materials", materialHandler.List)
+
+		r.Route("/filaments", func(r chi.Router) {
+			r.Get("/", filamentHandler.List)
+			r.Post("/", filamentHandler.Create)
+			r.Route("/{id}", func(r chi.Router) {
+				r.Get("/", filamentHandler.Get)
+				r.Put("/", filamentHandler.Update)
+				r.Delete("/", filamentHandler.Delete)
+			})
+		})
+
+		r.Get("/printers", printerHandler.List)
+		r.Get("/print-jobs", printJobHandler.List)
+		r.Get("/usage-logs", usageLogHandler.List)
+
+		// SSE Events stream
+		sseHandler := sse.NewHandler(sseBC)
+		r.Get("/events", sseHandler.ServeHTTP)
+	})
+
+	return r
+}

backend/internal/services/services.go

@@ -0,0 +1,82 @@
+// Package services contains business logic and application services.
+package services
+
+import (
+	"context"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/models"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/repositories"
+)
+
+// FilamentService wraps FilamentRepository with business logic and validation.
+type FilamentService struct {
+	repo *repositories.FilamentRepository
+}
+
+// NewFilamentService creates a FilamentService backed by the given repository.
+func NewFilamentService(repo *repositories.FilamentRepository) *FilamentService {
+	return &FilamentService{repo: repo}
+}
+
+// List returns paginated filament spools filtered by the given criteria.
+func (s *FilamentService) List(ctx context.Context, filter repositories.FilamentFilter) ([]models.FilamentSpool, int, error) {
+	return s.repo.GetAll(ctx, filter)
+}
+
+// GetByID returns a single filament spool by ID.
+func (s *FilamentService) GetByID(ctx context.Context, id int) (*models.FilamentSpool, error) {
+	return s.repo.GetByID(ctx, id)
+}
+
+// Create validates and creates a new filament spool.
+func (s *FilamentService) Create(ctx context.Context, spool *models.FilamentSpool) (*models.FilamentSpool, error) {
+	if err := validateFilamentSpool(spool); err != nil {
+		return nil, err
+	}
+	return s.repo.Create(ctx, spool)
+}
+
+// Update applies partial updates to a filament spool after validation.
+func (s *FilamentService) Update(ctx context.Context, id int, updates map[string]interface{}) (*models.FilamentSpool, error) {
+	return s.repo.Update(ctx, id, updates)
+}
+
+// SoftDelete marks a filament spool as deleted.
+func (s *FilamentService) SoftDelete(ctx context.Context, id int) (bool, error) {
+	return s.repo.SoftDelete(ctx, id)
+}
+
+// PrinterService wraps PrinterRepository.
+type PrinterService struct {
+	repo *repositories.PrinterRepository
+}
+
+// NewPrinterService creates a PrinterService backed by the given repository.
+func NewPrinterService(repo *repositories.PrinterRepository) *PrinterService {
+	return &PrinterService{repo: repo}
+}
+
+// List returns all printers.
+func (s *PrinterService) List(ctx context.Context) ([]models.Printer, error) {
+	return s.repo.GetAll(ctx)
+}
+
+// PrintJobService wraps PrintJobRepository.
+type PrintJobService struct {
+	repo *repositories.PrintJobRepository
+}
+
+// NewPrintJobService creates a PrintJobService backed by the given repository.
+func NewPrintJobService(repo *repositories.PrintJobRepository) *PrintJobService {
+	return &PrintJobService{repo: repo}
+}
+
+// List returns paginated print jobs filtered by the given criteria.
+func (s *PrintJobService) List(ctx context.Context, filter repositories.PrintJobFilter) ([]models.PrintJob, int, error) {
+	return s.repo.GetAll(ctx, filter)
+}
+
+// GetByID returns a single print job by ID.
+func (s *PrintJobService) GetByID(ctx context.Context, id int) (*models.PrintJob, error) {
+	return s.repo.GetByID(ctx, id)
+}

backend/internal/services/validation.go

@@ -0,0 +1,74 @@
+package services
+
+import (
+	"errors"
+	"fmt"
+	"regexp"
+
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/dtos"
+	"github.com/CubeCraft-Creations/Extrudex/backend/internal/models"
+)
+
+// colorHexPattern validates hex color strings like #FF0000 or #ff0000.
+var colorHexPattern = regexp.MustCompile(`^#[0-9A-Fa-f]{6}$`)
+
+// validateFilamentSpool performs validation on a FilamentSpool entity.
+// Returns a descriptive error on failure.
+func validateFilamentSpool(s *models.FilamentSpool) error {
+	if s.Name == "" {
+		return errors.New("name is required")
+	}
+	if s.MaterialBaseID <= 0 {
+		return errors.New("material_base_id is required")
+	}
+	if s.MaterialFinishID <= 0 {
+		return errors.New("material_finish_id is required")
+	}
+	if !colorHexPattern.MatchString(s.ColorHex) {
+		return fmt.Errorf("color_hex must be a valid hex color (e.g., #FF0000)")
+	}
+	if s.InitialGrams <= 0 {
+		return errors.New("initial_grams must be greater than 0")
+	}
+	if s.RemainingGrams < 0 {
+		return errors.New("remaining_grams must be >= 0")
+	}
+	return nil
+}
+
+// ValidateCreateFilamentRequest validates a creation DTO.
+func ValidateCreateFilamentRequest(req dtos.CreateFilamentRequest) error {
+	if req.Name == "" {
+		return errors.New("name is required")
+	}
+	if req.MaterialBaseID <= 0 {
+		return errors.New("material_base_id is required")
+	}
+	if req.MaterialFinishID <= 0 {
+		return errors.New("material_finish_id is required")
+	}
+	if !colorHexPattern.MatchString(req.ColorHex) {
+		return fmt.Errorf("color_hex must be a valid hex color (e.g., #FF0000)")
+	}
+	if req.InitialGrams <= 0 {
+		return errors.New("initial_grams must be greater than 0")
+	}
+	if req.RemainingGrams < 0 {
+		return errors.New("remaining_grams must be >= 0")
+	}
+	return nil
+}
+
+// ValidateUpdateFilamentRequest validates partial update fields.
+func ValidateUpdateFilamentRequest(req dtos.UpdateFilamentRequest) error {
+	if req.ColorHex != nil && !colorHexPattern.MatchString(*req.ColorHex) {
+		return fmt.Errorf("color_hex must be a valid hex color (e.g., #FF0000)")
+	}
+	if req.InitialGrams != nil && *req.InitialGrams <= 0 {
+		return errors.New("initial_grams must be greater than 0")
+	}
+	if req.RemainingGrams != nil && *req.RemainingGrams < 0 {
+		return errors.New("remaining_grams must be >= 0")
+	}
+	return nil
+}

backend/internal/sse/broadcaster.go

@@ -0,0 +1,133 @@
+package sse
+
+import (
+	"log/slog"
+	"sync"
+)
+
+// client represents a single SSE subscriber — identified by its send channel.
+type client struct {
+	ch chan string
+}
+
+// Broadcaster receives Events on its input channel and fans them out to every
+// connected client. Subscribe adds a new client; Unsubscribe removes one.
+// Start must be called before the broadcaster accepts events.
+type Broadcaster struct {
+	input       chan Event
+	subscribe   chan client
+	unsubscribe chan client
+	clients     map[chan string]struct{}
+	done        chan struct{}
+	once        sync.Once
+}
+
+// NewBroadcaster creates a Broadcaster. bufSize controls the buffer depth for
+// the input channel as well as for each per-client outbound channel.
+func NewBroadcaster(bufSize int) *Broadcaster {
+	if bufSize <= 0 {
+		bufSize = 64
+	}
+	return &Broadcaster{
+		input:       make(chan Event, bufSize),
+		subscribe:   make(chan client),
+		unsubscribe: make(chan client),
+		clients:     make(map[chan string]struct{}),
+		done:        make(chan struct{}),
+	}
+}
+
+// Publish pushes an event into the broadcaster. Safe for concurrent use.
+func (b *Broadcaster) Publish(ev Event) {
+	select {
+	case b.input <- ev:
+	case <-b.done:
+		// Silently drop during shutdown.
+	}
+}
+
+// Start launches the broadcaster's fan-out loop in a goroutine.
+// It must be called before Publish is used.
+func (b *Broadcaster) Start() {
+	go b.loop()
+}
+
+// Stop terminates the fan-out loop and closes all client channels.
+// It is safe to call multiple times.
+func (b *Broadcaster) Stop() {
+	b.once.Do(func() {
+		close(b.done)
+	})
+}
+
+// Subscribe returns a new client channel that receives SSE-formatted strings.
+func (b *Broadcaster) Subscribe() chan string {
+	c := client{ch: make(chan string, 64)}
+	select {
+	case b.subscribe <- c:
+	case <-b.done:
+		// Broadcaster already stopped — return a closed chan so the handler
+		// can bail out quickly.
+		ch := make(chan string)
+		close(ch)
+		return ch
+	}
+	return c.ch
+}
+
+// Unsubscribe removes a client channel and closes it.
+func (b *Broadcaster) Unsubscribe(ch chan string) {
+	c := client{ch: ch}
+	select {
+	case b.unsubscribe <- c:
+	case <-b.done:
+		// Already shutting down — channels will be cleaned up by Stop.
+	}
+}
+
+// loop is the core fan-out goroutine.
+func (b *Broadcaster) loop() {
+	for {
+		select {
+		case ev := <-b.input:
+			sse := ev.toSSE()
+			for ch := range b.clients {
+				// Non-blocking send — slow clients are dropped.
+				select {
+				case ch <- sse:
+				default:
+					slog.Warn("sse broadcaster: dropping event for slow client", "type", ev.Type)
+				}
+			}
+
+		case c := <-b.subscribe:
+			b.clients[c.ch] = struct{}{}
+			slog.Debug("sse broadcaster: client connected", "total_clients", len(b.clients))
+
+		case c := <-b.unsubscribe:
+			if _, ok := b.clients[c.ch]; ok {
+				delete(b.clients, c.ch)
+				close(c.ch)
+				slog.Debug("sse broadcaster: client disconnected", "total_clients", len(b.clients))
+			}
+
+		case <-b.done:
+			// Drain remaining events in input before shutting down.
+			for ev := range b.input {
+				sse := ev.toSSE()
+				for ch := range b.clients {
+					select {
+					case ch <- sse:
+					default:
+					}
+				}
+			}
+			// Close all remaining client channels.
+			for ch := range b.clients {
+				close(ch)
+			}
+			b.clients = nil
+			return
+		}
+	}
+}

backend/internal/sse/events.go

@@ -0,0 +1,92 @@
+// Package sse provides Server-Sent Events infrastructure for real-time updates.
+// Includes event types, a central broadcaster, and an HTTP handler.
+package sse
+
+import (
+	"encoding/json"
+	"time"
+)
+
+// EventType identifies the category of an SSE event.
+type EventType string
+
+const (
+	EventPrinterStatus  EventType = "printer.status"
+	EventJobStarted     EventType = "job.started"
+	EventJobCompleted   EventType = "job.completed"
+	EventFilamentLow    EventType = "filament.low"
+)
+
+// Event is a JSON-serializable SSE event pushed through the broadcaster.
+type Event struct {
+	Type      EventType       `json:"type"`
+	Payload   json.RawMessage `json:"payload"`
+	Timestamp time.Time       `json:"timestamp"`
+}
+
+// PrinterStatusPayload carries printer online/offline/printing state.
+type PrinterStatusPayload struct {
+	PrinterID   int    `json:"printer_id"`
+	PrinterName string `json:"printer_name"`
+	Status      string `json:"status"` // "online", "offline", "printing"
+}
+
+// JobStartedPayload carries initial print job info.
+type JobStartedPayload struct {
+	JobID      int    `json:"job_id"`
+	JobName    string `json:"job_name"`
+	PrinterID  int    `json:"printer_id"`
+	SpoolID    *int   `json:"spool_id,omitempty"`
+}
+
+// JobCompletedPayload carries final print job data including usage.
+type JobCompletedPayload struct {
+	JobID           int     `json:"job_id"`
+	JobName         string  `json:"job_name"`
+	PrinterID       int     `json:"printer_id"`
+	DurationSeconds *int    `json:"duration_seconds,omitempty"`
+	TotalGramsUsed  *float64 `json:"total_grams_used,omitempty"`
+	TotalCostUSD    *float64 `json:"total_cost_usd,omitempty"`
+}
+
+// FilamentLowPayload alerts that a spool is below its threshold.
+type FilamentLowPayload struct {
+	SpoolID       int    `json:"spool_id"`
+	SpoolName     string `json:"spool_name"`
+	RemainingGrams int   `json:"remaining_grams"`
+	ThresholdGrams int   `json:"threshold_grams"`
+}
+
+// NewEvent creates an Event with the current timestamp from a typed payload.
+func NewEvent(eventType EventType, payload any) (Event, error) {
+	raw, err := json.Marshal(payload)
+	if err != nil {
+		return Event{}, err
+	}
+	return Event{
+		Type:      eventType,
+		Payload:   raw,
+		Timestamp: time.Now().UTC(),
+	}, nil
+}
+
+// MustEvent creates an Event and panics on marshal failure (for use with
+// known-good payloads in tests and internal wiring).
+func MustEvent(eventType EventType, payload any) Event {
+	ev, err := NewEvent(eventType, payload)
+	if err != nil {
+		panic("sse.MustEvent: failed to marshal payload: " + err.Error())
+	}
+	return ev
+}
+
+// toSSE formats this Event as a standard SSE message string ready to be
+// written to a response writer. The format is:
+//
+//	event: <type>
+//	data: <json>
+//
+func (e Event) toSSE() string {
+	data, _ := json.Marshal(e)
+	return "event: " + string(e.Type) + "\n" + "data: " + string(data) + "\n\n"
+}

backend/internal/sse/handler.go

@@ -0,0 +1,59 @@
+package sse
+
+import (
+	"net/http"
+)
+
+// Handler is the HTTP handler for the GET /api/events SSE stream.
+// It registers a client with the broadcaster, streams events as they arrive,
+// and unregisters on disconnect.
+type Handler struct {
+	bc *Broadcaster
+}
+
+// NewHandler creates a Handler backed by the given Broadcaster.
+func NewHandler(bc *Broadcaster) *Handler {
+	return &Handler{bc: bc}
+}
+
+// ServeHTTP implements the SSE streaming endpoint.
+// Flusher is required; clients that do not support flushing receive a 501.
+func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	flusher, ok := w.(http.Flusher)
+	if !ok {
+		http.Error(w, "streaming not supported", http.StatusNotImplemented)
+		return
+	}
+
+	// SSE-specific headers
+	w.Header().Set("Content-Type", "text/event-stream")
+	w.Header().Set("Cache-Control", "no-cache")
+	w.Header().Set("Connection", "keep-alive")
+	w.Header().Set("X-Accel-Buffering", "no") // Disable nginx buffering
+
+	// Write headers immediately
+	flusher.Flush()
+
+	// Subscribe to the broadcaster
+	ch := h.bc.Subscribe()
+	defer h.bc.Unsubscribe(ch)
+
+	// Use request context for cancellation when the client disconnects.
+	ctx := r.Context()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case msg, ok := <-ch:
+			if !ok {
+				return
+			}
+			_, err := w.Write([]byte(msg))
+			if err != nil {
+				return
+			}
+			flusher.Flush()
+		}
+	}
+}

backend/migrations/000001_initial_schema.down.sql

@@ -0,0 +1,19 @@
+-- Migration: 000001_initial_schema (rollback)
+-- Description: Drop all tables and indexes created in the initial schema migration
+-- Author: Hex
+-- Date: 2026-05-06
+
+BEGIN;
+
+DROP TABLE IF EXISTS usage_logs        CASCADE;
+DROP TABLE IF EXISTS print_jobs        CASCADE;
+DROP TABLE IF EXISTS filament_spools   CASCADE;
+DROP TABLE IF EXISTS printers          CASCADE;
+DROP TABLE IF EXISTS settings          CASCADE;
+DROP TABLE IF EXISTS material_modifiers CASCADE;
+DROP TABLE IF EXISTS material_finishes  CASCADE;
+DROP TABLE IF EXISTS material_bases     CASCADE;
+DROP TABLE IF EXISTS job_statuses       CASCADE;
+DROP TABLE IF EXISTS printer_types      CASCADE;
+
+COMMIT;

backend/migrations/000001_initial_schema.up.sql

@@ -0,0 +1,231 @@
+-- Migration: 000001_initial_schema
+-- Description: Create initial Extrudex schema — lookup tables, core entities, and settings
+-- Author: Hex
+-- Date: 2026-05-06
+--
+-- Design decisions:
+--   - Lookup tables for material_base, material_finish, material_modifier (no free-text enums)
+--   - Lookup tables for printer_type and job_status (extensible, no hard-coded enum values)
+--   - FK ON DELETE: RESTRICT on critical parents (material_base, material_finish, printer),
+--     SET NULL on optional parents (modifier, spool on print_jobs),
+--     CASCADE for usage_logs when parent job is deleted
+--   - Soft-delete (deleted_at) on spools and print_jobs for safety
+--   - JSONB config column on settings for flexible app-wide configuration
+--   - All identifiers snake_case per project convention
+
+BEGIN;
+
+-- ============================================================================
+-- Lookup Tables
+-- ============================================================================
+
+-- Printer types (fdm, resin, etc.) — extensible, not a raw enum
+CREATE TABLE printer_types (
+    id          SERIAL PRIMARY KEY,
+    name        VARCHAR(50) NOT NULL UNIQUE,
+    created_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at  TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- Job statuses (pending, printing, paused, completed, failed, cancelled)
+CREATE TABLE job_statuses (
+    id          SERIAL PRIMARY KEY,
+    name        VARCHAR(50) NOT NULL UNIQUE,
+    created_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at  TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- Material base types (PLA, PETG, ABS, TPU, ASA, Nylon, PC)
+CREATE TABLE material_bases (
+    id                  SERIAL PRIMARY KEY,
+    name                VARCHAR(100) NOT NULL UNIQUE,
+    density_g_cm3       DECIMAL(5,3) NOT NULL,
+    extrusion_temp_min  INT,
+    extrusion_temp_max  INT,
+    bed_temp_min        INT,
+    bed_temp_max        INT,
+    created_at          TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at          TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- Material finishes (Basic, Silk, Matte, Glossy, Satin)
+CREATE TABLE material_finishes (
+    id          SERIAL PRIMARY KEY,
+    name        VARCHAR(100) NOT NULL UNIQUE,
+    description TEXT,
+    created_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at  TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- Material modifiers (Wood-Filled, Carbon Fiber, Glow-in-Dark, Marble)
+CREATE TABLE material_modifiers (
+    id          SERIAL PRIMARY KEY,
+    name        VARCHAR(100) NOT NULL UNIQUE,
+    description TEXT,
+    created_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at  TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- ============================================================================
+-- Core Entity Tables
+-- ============================================================================
+
+-- 3D printers in the fleet
+CREATE TABLE printers (
+    id                  SERIAL PRIMARY KEY,
+    name                VARCHAR(255) NOT NULL,
+    printer_type_id     INT NOT NULL,
+    manufacturer        VARCHAR(255),
+    model               VARCHAR(255),
+    moonraker_url       VARCHAR(512),
+    moonraker_api_key   VARCHAR(512),
+    mqtt_broker_host    VARCHAR(255),
+    mqtt_topic_prefix   VARCHAR(255),
+    mqtt_tls_enabled    BOOLEAN NOT NULL DEFAULT FALSE,
+    is_active           BOOLEAN NOT NULL DEFAULT TRUE,
+    created_at          TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at          TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+
+    CONSTRAINT fk_printers_printer_type
+        FOREIGN KEY (printer_type_id) REFERENCES printer_types(id)
+        ON DELETE RESTRICT
+);
+
+-- Filament spools — the core inventory item
+CREATE TABLE filament_spools (
+    id                      SERIAL PRIMARY KEY,
+    name                    VARCHAR(255) NOT NULL,
+    material_base_id        INT NOT NULL,
+    material_finish_id      INT NOT NULL DEFAULT 1,  -- "Basic" (seed data populates this first)
+    material_modifier_id    INT,
+    color_hex               VARCHAR(7) NOT NULL CHECK (color_hex ~ '^#[0-9A-Fa-f]{6}$'),
+    brand                   VARCHAR(255),
+    diameter_mm             DECIMAL(4,2) NOT NULL DEFAULT 1.75,
+    initial_grams           INT NOT NULL CHECK (initial_grams > 0),
+    remaining_grams         INT NOT NULL CHECK (remaining_grams >= 0),
+    spool_weight_grams      INT,  -- measured empty-spool weight (tare), nullable
+    cost_usd                DECIMAL(10,2),
+    low_stock_threshold_grams INT NOT NULL DEFAULT 50,
+    notes                   TEXT,
+    barcode                 VARCHAR(255) UNIQUE,
+    deleted_at              TIMESTAMPTZ,
+    created_at              TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at              TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+
+    CONSTRAINT fk_spools_material_base
+        FOREIGN KEY (material_base_id) REFERENCES material_bases(id)
+        ON DELETE RESTRICT,
+
+    CONSTRAINT fk_spools_material_finish
+        FOREIGN KEY (material_finish_id) REFERENCES material_finishes(id)
+        ON DELETE RESTRICT,
+
+    CONSTRAINT fk_spools_material_modifier
+        FOREIGN KEY (material_modifier_id) REFERENCES material_modifiers(id)
+        ON DELETE SET NULL
+);
+
+-- Print jobs — each job is one print on one printer
+CREATE TABLE print_jobs (
+    id                      SERIAL PRIMARY KEY,
+    printer_id              INT NOT NULL,
+    filament_spool_id       INT,  -- nullable: a job may use multiple spools (captured in usage_logs)
+    job_name                VARCHAR(255) NOT NULL,
+    file_name               VARCHAR(512),
+    job_status_id           INT NOT NULL DEFAULT 1,  -- "pending"
+    started_at              TIMESTAMPTZ,
+    completed_at            TIMESTAMPTZ,
+    duration_seconds        INT,
+    estimated_duration_seconds INT,
+    total_mm_extruded       DECIMAL(12,2),
+    total_grams_used        DECIMAL(10,2),
+    total_cost_usd          DECIMAL(10,4),
+    notes                   TEXT,
+    deleted_at              TIMESTAMPTZ,
+    created_at              TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at              TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+
+    CONSTRAINT fk_print_jobs_printer
+        FOREIGN KEY (printer_id) REFERENCES printers(id)
+        ON DELETE RESTRICT,
+
+    CONSTRAINT fk_print_jobs_spool
+        FOREIGN KEY (filament_spool_id) REFERENCES filament_spools(id)
+        ON DELETE SET NULL,
+
+    CONSTRAINT fk_print_jobs_status
+        FOREIGN KEY (job_status_id) REFERENCES job_statuses(id)
+        ON DELETE RESTRICT
+);
+
+-- Usage logs — granular tracking of filament consumed per job, per spool
+CREATE TABLE usage_logs (
+    id                  SERIAL PRIMARY KEY,
+    print_job_id        INT NOT NULL,
+    filament_spool_id   INT NOT NULL,
+    mm_extruded         DECIMAL(12,2) NOT NULL CHECK (mm_extruded > 0),
+    grams_used          DECIMAL(10,2) NOT NULL CHECK (grams_used > 0),
+    cost_usd            DECIMAL(10,4),
+    logged_at           TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    created_at          TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+
+    CONSTRAINT fk_usage_logs_print_job
+        FOREIGN KEY (print_job_id) REFERENCES print_jobs(id)
+        ON DELETE CASCADE,
+
+    CONSTRAINT fk_usage_logs_spool
+        FOREIGN KEY (filament_spool_id) REFERENCES filament_spools(id)
+        ON DELETE RESTRICT
+);
+
+-- ============================================================================
+-- Application Settings
+-- ============================================================================
+
+CREATE TABLE settings (
+    id          SERIAL PRIMARY KEY,
+    key         VARCHAR(255) NOT NULL UNIQUE,
+    value       JSONB NOT NULL,
+    description TEXT,
+    created_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at  TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- ============================================================================
+-- Indexes
+-- ============================================================================
+
+-- Filament spools — query patterns: lookup by material, low-stock scans, barcode scans
+CREATE INDEX ix_spools_material_base_id     ON filament_spools(material_base_id);
+CREATE INDEX ix_spools_material_finish_id   ON filament_spools(material_finish_id);
+CREATE INDEX ix_spools_material_modifier_id ON filament_spools(material_modifier_id);
+CREATE INDEX ix_spools_remaining_grams      ON filament_spools(remaining_grams)
+    WHERE deleted_at IS NULL;  -- partial index: only active spools for low-stock queries
+CREATE INDEX ix_spools_barcode              ON filament_spools(barcode)
+    WHERE barcode IS NOT NULL AND deleted_at IS NULL;
+CREATE INDEX ix_spools_deleted_at           ON filament_spools(deleted_at)
+    WHERE deleted_at IS NOT NULL;  -- small index for soft-delete filtering
+
+-- Printers
+CREATE INDEX ix_printers_printer_type_id ON printers(printer_type_id);
+CREATE INDEX ix_printers_is_active       ON printers(is_active)
+    WHERE is_active = TRUE;  -- partial index for fleet dashboard queries
+
+-- Print jobs — query by printer, status, date range, and soft-delete filter
+CREATE INDEX ix_print_jobs_printer_id   ON print_jobs(printer_id);
+CREATE INDEX ix_print_jobs_spool_id     ON print_jobs(filament_spool_id)
+    WHERE filament_spool_id IS NOT NULL;
+CREATE INDEX ix_print_jobs_status_id    ON print_jobs(job_status_id);
+CREATE INDEX ix_print_jobs_created_at   ON print_jobs(created_at DESC);
+CREATE INDEX ix_print_jobs_deleted_at   ON print_jobs(deleted_at)
+    WHERE deleted_at IS NOT NULL;
+
+-- Usage logs — always queried by job or spool
+CREATE INDEX ix_usage_logs_print_job_id ON usage_logs(print_job_id);
+CREATE INDEX ix_usage_logs_spool_id     ON usage_logs(filament_spool_id);
+CREATE INDEX ix_usage_logs_logged_at    ON usage_logs(logged_at DESC);
+
+-- Settings — key lookups
+CREATE INDEX ix_settings_key ON settings(key);
+
+COMMIT;

backend/migrations/000002_seed_data.down.sql

@@ -0,0 +1,15 @@
+-- Migration: 000002_seed_data (rollback)
+-- Description: Remove seed data inserted in 000002
+-- Author: Hex
+-- Date: 2026-05-06
+
+BEGIN;
+
+DELETE FROM settings            WHERE key IN ('default_low_stock_threshold_grams', 'default_diameter_mm', 'filament_cross_section_area_mm2');
+DELETE FROM material_modifiers  WHERE id IN (1, 2, 3, 4);
+DELETE FROM material_finishes   WHERE id IN (1, 2, 3, 4, 5);
+DELETE FROM material_bases      WHERE id IN (1, 2, 3, 4, 5, 6, 7);
+DELETE FROM job_statuses        WHERE id IN (1, 2, 3, 4, 5, 6);
+DELETE FROM printer_types       WHERE id IN (1, 2);
+
+COMMIT;

backend/migrations/000002_seed_data.up.sql

@@ -0,0 +1,95 @@
+-- Seed Data: Extrudex common reference data
+-- Author: Hex
+-- Date: 2026-05-06
+--
+-- IMPORTANT: IDs are explicitly assigned to satisfy the DEFAULT constraints:
+--   - filament_spools.material_finish_id  DEFAULT 1  ("Basic")
+--   - print_jobs.job_status_id            DEFAULT 1  ("pending")
+--
+-- Density values sourced from common manufacturer specifications.
+-- Temperature ranges are conservative/typical; users can override per-spool.
+
+BEGIN;
+
+-- ============================================================================
+-- Printer Types
+-- ============================================================================
+
+INSERT INTO printer_types (id, name) VALUES
+    (1, 'fdm'),
+    (2, 'resin')
+ON CONFLICT (id) DO NOTHING;
+
+-- Reset the sequence so future inserts start after our explicit IDs
+SELECT setval('printer_types_id_seq', GREATEST(2, (SELECT MAX(id) FROM printer_types)));
+
+-- ============================================================================
+-- Job Statuses
+-- ============================================================================
+
+INSERT INTO job_statuses (id, name) VALUES
+    (1, 'pending'),
+    (2, 'printing'),
+    (3, 'paused'),
+    (4, 'completed'),
+    (5, 'failed'),
+    (6, 'cancelled')
+ON CONFLICT (id) DO NOTHING;
+
+SELECT setval('job_statuses_id_seq', GREATEST(6, (SELECT MAX(id) FROM job_statuses)));
+
+-- ============================================================================
+-- Material Bases (common filament types)
+-- ============================================================================
+
+INSERT INTO material_bases (id, name, density_g_cm3, extrusion_temp_min, extrusion_temp_max, bed_temp_min, bed_temp_max) VALUES
+    (1, 'PLA',   1.24, 190, 220,  0,  60),
+    (2, 'PETG',  1.27, 230, 250, 70,  90),
+    (3, 'ABS',   1.04, 230, 260, 90, 110),
+    (4, 'TPU',   1.21, 220, 250,  0,  60),
+    (5, 'ASA',   1.07, 240, 260, 90, 110),
+    (6, 'Nylon', 1.14, 240, 280, 70, 100),
+    (7, 'PC',    1.20, 260, 310, 90, 120)
+ON CONFLICT (id) DO NOTHING;
+
+SELECT setval('material_bases_id_seq', GREATEST(7, (SELECT MAX(id) FROM material_bases)));
+
+-- ============================================================================
+-- Material Finishes
+-- ============================================================================
+-- ID 1 = "Basic" is the default for new spools (DEFAULT 1 constraint)
+
+INSERT INTO material_finishes (id, name, description) VALUES
+    (1, 'Basic',  'Standard solid-color filament with no special finish'),
+    (2, 'Silk',   'Glossy silk-like sheen, often used for decorative prints'),
+    (3, 'Matte',  'Flat non-reflective surface finish'),
+    (4, 'Glossy', 'High-shine reflective surface'),
+    (5, 'Satin',  'Semi-gloss between matte and glossy')
+ON CONFLICT (id) DO NOTHING;
+
+SELECT setval('material_finishes_id_seq', GREATEST(5, (SELECT MAX(id) FROM material_finishes)));
+
+-- ============================================================================
+-- Material Modifiers
+-- ============================================================================
+
+INSERT INTO material_modifiers (id, name, description) VALUES
+    (1, 'Wood-Filled',   'Contains wood fibers for natural wood-like appearance and texture'),
+    (2, 'Carbon Fiber',  'Reinforced with carbon fibers for increased stiffness and strength'),
+    (3, 'Glow-in-Dark',  'Phosphorescent additive that glows after exposure to light'),
+    (4, 'Marble',        'Contains specks for a stone-like marble appearance')
+ON CONFLICT (id) DO NOTHING;
+
+SELECT setval('material_modifiers_id_seq', GREATEST(4, (SELECT MAX(id) FROM material_modifiers)));
+
+-- ============================================================================
+-- Default Application Settings
+-- ============================================================================
+
+INSERT INTO settings (key, value, description) VALUES
+    ('default_low_stock_threshold_grams', '50', 'Default grams threshold for low-stock alerts on new spools'),
+    ('default_diameter_mm', '1.75', 'Default filament diameter for new spools (1.75mm is the modern standard)'),
+    ('filament_cross_section_area_mm2', '2.405', 'Cross-sectional area for 1.75mm filament: π × (1.75/2)²')
+ON CONFLICT (key) DO NOTHING;
+
+COMMIT;

frontend/.gitignore

@@ -1,44 +0,0 @@
-# See https://docs.github.com/get-started/getting-started-with-git/ignoring-files for more about ignoring files.
-
-# Compiled output
-/dist
-/tmp
-/out-tsc
-/bazel-out
-
-# Node
-/node_modules
-npm-debug.log
-yarn-error.log
-
-# IDEs and editors
-.idea/
-.project
-.classpath
-.c9/
-*.launch
-.settings/
-*.sublime-workspace
-
-# Visual Studio Code
-.vscode/*
-!.vscode/settings.json
-!.vscode/tasks.json
-!.vscode/launch.json
-!.vscode/extensions.json
-!.vscode/mcp.json
-.history/*
-
-# Miscellaneous
-/.angular/cache
-.sass-cache/
-/connect.lock
-/coverage
-/libpeerconnection.log
-testem.log
-/typings
-__screenshots__/
-
-# System files
-.DS_Store
-Thumbs.db

frontend/Dockerfile

@@ -1,20 +1,14 @@
-# Multi-stage build for production
+# Build stage
 FROM node:22-alpine AS builder
-
 WORKDIR /app
-
 COPY package*.json ./
 RUN npm ci
-
 COPY . .
 RUN npm run build
 
-# Production stage — serve with nginx
+# Serve stage
 FROM nginx:alpine
-
 COPY --from=builder /app/dist /usr/share/nginx/html
 COPY nginx.conf /etc/nginx/conf.d/default.conf
-
 EXPOSE 80
-
 CMD ["nginx", "-g", "daemon off;"]

frontend/eslint.config.js

@@ -10,7 +10,7 @@ export default tseslint.config(
     extends: [js.configs.recommended, ...tseslint.configs.recommended],
     files: ['**/*.{ts,tsx}'],
     languageOptions: {
-      ecmaVersion: 2023,
+      ecmaVersion: 2020,
       globals: globals.browser,
     },
     plugins: {

frontend/index.html

@@ -4,7 +4,6 @@
     <meta charset="UTF-8" />
     <link rel="icon" type="image/svg+xml" href="/vite.svg" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <meta name="theme-color" content="#0f172a" />
     <title>Extrudex</title>
   </head>
   <body>

frontend/nginx.conf

@@ -1,16 +1,23 @@
 server {
-    listen       80;
+    listen 80;
-    listen  [::]:80;
+    server_name _;
-    server_name  localhost;
+
+    root /usr/share/nginx/html;
+    index index.html;
 
     location / {
-        root   /usr/share/nginx/html;
-        index  index.html;
         try_files $uri $uri/ /index.html;
     }
 
-    error_page   500 502 503 504  /50x.html;
+    location /api/ {
-    location = /50x.html {
+        proxy_pass http://backend:8080/api/;
-        root   /usr/share/nginx/html;
+        proxy_http_version 1.1;
+        proxy_set_header Upgrade $http_upgrade;
+        proxy_set_header Connection 'upgrade';
+        proxy_set_header Host $host;
+        proxy_cache_bypass $http_upgrade;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto $scheme;
     }
 }

frontend/package.json

@@ -1,36 +1,35 @@
 {
   "name": "extrudex-frontend",
   "private": true,
-  "version": "0.0.0",
+  "version": "0.0.1",
   "type": "module",
   "scripts": {
     "dev": "vite",
-    "build": "tsc -b && vite build",
+    "build": "tsc && vite build",
-    "lint": "eslint .",
+    "lint": "eslint . --ext ts,tsx --report-unused-disable-directives --max-warnings 0",
     "preview": "vite preview"
   },
   "dependencies": {
-    "@tailwindcss/vite": "^4.2.4",
+    "@tanstack/react-query": "^5.60.0",
-    "@tanstack/react-query": "^5.100.9",
+    "axios": "^1.7.0",
-    "axios": "^1.16.0",
+    "lucide-react": "^0.460.0",
-    "react": "^19.2.5",
+    "react": "^19.0.0",
-    "react-dom": "^19.2.5",
+    "react-dom": "^19.0.0",
-    "react-router-dom": "^7.15.0",
+    "react-router-dom": "^7.0.0"
-    "tailwindcss": "^4.2.4",
-    "zustand": "^5.0.13"
   },
   "devDependencies": {
-    "@eslint/js": "^10.0.1",
+    "@tailwindcss/postcss": "^4.2.4",
-    "@types/react": "^19.2.14",
+    "@tailwindcss/vite": "^4.2.4",
-    "@types/react-dom": "^19.2.3",
+    "@types/react": "^19.0.0",
-    "@types/react-router-dom": "^5.3.3",
+    "@types/react-dom": "^19.0.0",
-    "@vitejs/plugin-react": "^6.0.1",
+    "@vitejs/plugin-react": "^4.3.0",
-    "eslint": "^10.2.1",
+    "autoprefixer": "^10.4.20",
-    "eslint-plugin-react-hooks": "^7.1.1",
+    "eslint": "^9.15.0",
-    "eslint-plugin-react-refresh": "^0.5.2",
+    "eslint-plugin-react-hooks": "^5.0.0",
-    "globals": "^17.5.0",
+    "eslint-plugin-react-refresh": "^0.4.14",
-    "typescript": "~6.0.2",
+    "postcss": "^8.4.49",
-    "typescript-eslint": "^8.58.2",
+    "tailwindcss": "^4.0.0",
-    "vite": "^8.0.10"
+    "typescript": "~5.6.0",
+    "vite": "^6.0.0"
   }
 }

frontend/postcss.config.js

@@ -0,0 +1,5 @@
+export default {
+  plugins: {
+    '@tailwindcss/postcss': {},
+  },
+}

frontend/src/App.tsx

@@ -1,17 +1,25 @@
-import { Routes, Route } from 'react-router-dom'
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
-import ErrorBoundary from './components/ErrorBoundary'
+import { BrowserRouter, Routes, Route } from 'react-router-dom'
-import HomePage from './pages/HomePage'
+import InventoryPage from './pages/InventoryPage'
 
-function App() {
+const queryClient = new QueryClient()
+
+export default function App() {
   return (
-    <ErrorBoundary>
+    <QueryClientProvider client={queryClient}>
-      <div className="min-h-screen bg-slate-900 text-slate-100">
+      <BrowserRouter>
-        <Routes>
+        <div className="min-h-screen bg-slate-900 text-slate-50">
-          <Route path="/" element={<HomePage />} />
+          <header className="bg-slate-800 border-b border-slate-700 px-4 py-3 flex items-center gap-3 sticky top-0 z-20">
-        </Routes>
+            <div className="w-8 h-8 rounded bg-emerald-500 flex items-center justify-center text-slate-900 font-bold text-lg">E</div>
-      </div>
+            <h1 className="text-lg font-semibold">Extrudex</h1>
-    </ErrorBoundary>
+          </header>
+          <main className="p-4">
+            <Routes>
+              <Route path="/" element={<InventoryPage />} />
+            </Routes>
+          </main>
+        </div>
+      </BrowserRouter>
+    </QueryClientProvider>
   )
 }
-
-export default App

frontend/src/components/ColorSwatch.tsx

@@ -0,0 +1,18 @@
+interface ColorSwatchProps {
+  colorHex: string
+  size?: number
+}
+
+export default function ColorSwatch({ colorHex, size = 24 }: ColorSwatchProps) {
+  return (
+    <div
+      className="rounded-full border border-slate-600 shadow-sm inline-block"
+      style={{
+        backgroundColor: colorHex.startsWith('#') ? colorHex : `#${colorHex}`,
+        width: size,
+        height: size,
+      }}
+      title={colorHex}
+    />
+  )
+}

frontend/src/components/ErrorBoundary.tsx

@@ -1,50 +0,0 @@
-import { Component, type ReactNode } from 'react'
-
-interface Props {
-  children: ReactNode
-}
-
-interface State {
-  hasError: boolean
-  error?: Error
-}
-
-class ErrorBoundary extends Component<Props, State> {
-  constructor(props: Props) {
-    super(props)
-    this.state = { hasError: false }
-  }
-
-  static getDerivedStateFromError(error: Error): State {
-    return { hasError: true, error }
-  }
-
-  componentDidCatch(error: Error, info: React.ErrorInfo) {
-    // eslint-disable-next-line no-console
-    console.error('ErrorBoundary caught:', error, info)
-  }
-
-  render() {
-    if (this.state.hasError) {
-      return (
-        <div className="flex min-h-screen items-center justify-center p-4">
-          <div className="rounded-xl border border-red-500/30 bg-red-950/40 p-6 text-center shadow-lg backdrop-blur-sm">
-            <h2 className="mb-2 text-xl font-semibold text-red-400">Something went wrong</h2>
-            <p className="mb-4 text-sm text-red-300">
-              {this.state.error?.message || 'An unexpected error occurred.'}
-            </p>
-            <button
-              onClick={() => window.location.reload()}
-              className="rounded-lg bg-red-600 px-4 py-2 text-sm font-medium text-white hover:bg-red-700"
-            >
-              Reload Page
-            </button>
-          </div>
-        </div>
-      )
-    }
-    return this.props.children
-  }
-}
-
-export default ErrorBoundary

frontend/src/components/ErrorState.tsx

@@ -1,21 +0,0 @@
-export default function ErrorState({
-  message = 'Something went wrong.',
-  onRetry,
-}: {
-  message?: string
-  onRetry?: () => void
-}) {
-  return (
-    <div className="flex min-h-[120px] flex-col items-center justify-center gap-3 rounded-xl border border-red-500/20 bg-red-950/30 p-6 text-center">
-      <p className="text-sm text-red-300">{message}</p>
-      {onRetry && (
-        <button
-          onClick={onRetry}
-          className="rounded-lg bg-red-600 px-3 py-1.5 text-xs font-medium text-white hover:bg-red-700"
-        >
-          Retry
-        </button>
-      )}
-    </div>
-  )
-}

frontend/src/components/LoadingSpinner.tsx

@@ -1,14 +0,0 @@
-export default function LoadingSpinner({ size = 'md' }: { size?: 'sm' | 'md' | 'lg' }) {
-  const sizeClass =
-    size === 'sm' ? 'h-4 w-4 border-2' : size === 'lg' ? 'h-10 w-10 border-4' : 'h-6 w-6 border-2'
-
-  return (
-    <div className="flex items-center justify-center p-4">
-      <div
-        className={`${sizeClass} animate-spin rounded-full border-slate-600 border-t-sky-400`}
-        role="status"
-        aria-label="Loading"
-      />
-    </div>
-  )
-}

frontend/src/hooks/useHealth.ts

@@ -1,11 +0,0 @@
-import { useQuery } from '@tanstack/react-query'
-import { healthCheck } from '../services/api'
-
-export function useHealth() {
-  return useQuery({
-    queryKey: ['health'],
-    queryFn: healthCheck,
-    retry: 2,
-    refetchInterval: 30000,
-  })
-}

frontend/src/index.css

@@ -2,9 +2,7 @@
 
 body {
   margin: 0;
-  min-width: 320px;
   min-height: 100vh;
-  background-color: #0f172a;
+  background-color: #0f172a; /* slate-900 */
-  color: #e2e8f0;
+  color: #f8fafc; /* slate-50 */
-  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
 }

frontend/src/main.tsx

@@ -1,18 +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.tsx'
+import App from './App'
-
-const queryClient = new QueryClient()
 
 createRoot(document.getElementById('root')!).render(
   <StrictMode>
-    <QueryClientProvider client={queryClient}>
+    <App />
-      <BrowserRouter>
-        <App />
-      </BrowserRouter>
-    </QueryClientProvider>
   </StrictMode>,
 )

frontend/src/pages/HomePage.tsx

@@ -1,36 +0,0 @@
-import LoadingSpinner from '../components/LoadingSpinner'
-import ErrorState from '../components/ErrorState'
-import { useHealth } from '../hooks/useHealth'
-
-export default function HomePage() {
-  const { data, isLoading, isError, refetch } = useHealth()
-
-  return (
-    <div className="flex min-h-screen flex-col items-center justify-center gap-6 p-6">
-      <h1 className="text-3xl font-bold tracking-tight text-sky-400">Extrudex</h1>
-      <p className="text-slate-400">Filament inventory &amp; print tracking</p>
-
-      <div className="w-full max-w-md rounded-xl border border-slate-700 bg-slate-800/60 p-6 shadow-lg backdrop-blur-sm">
-        <h2 className="mb-3 text-sm font-semibold uppercase tracking-wider text-slate-400">
-          Backend Health
-        </h2>
-
-        {isLoading && <LoadingSpinner />}
-
-        {isError && (
-          <ErrorState
-            message="Backend is unreachable."
-            onRetry={() => refetch()}
-          />
-        )}
-
-        {data && (
-          <div className="flex items-center gap-2 text-emerald-400">
-            <span className="h-2 w-2 rounded-full bg-emerald-400" />
-            <span className="text-sm font-medium">{data.status || 'ok'}</span>
-          </div>
-        )}
-      </div>
-    </div>
-  )
-}

frontend/src/pages/InventoryPage.tsx

@@ -0,0 +1,339 @@
+import { useState, useMemo } from 'react'
+import { useQuery } from '@tanstack/react-query'
+import { Search, Filter, ChevronLeft, ChevronRight, Trash2, Pencil, Plus, AlertTriangle } from 'lucide-react'
+import ColorSwatch from '../components/ColorSwatch'
+import { fetchFilaments, deleteFilament } from '../services/filamentService'
+import type { FilamentSpool, FilamentFilter } from '../types/filament'
+
+const PAGE_SIZE = 20
+
+type SortField = 'name' | 'remaining_grams' | 'cost_usd'
+type SortDir = 'asc' | 'desc'
+
+export default function InventoryPage() {
+  const [search, setSearch] = useState('')
+  const [material, setMaterial] = useState('')
+  const [finish, setFinish] = useState('')
+  const [lowStockOnly, setLowStockOnly] = useState(false)
+  const [sortBy, setSortBy] = useState<SortField>('name')
+  const [sortDir, setSortDir] = useState<SortDir>('asc')
+  const [page, setPage] = useState(0)
+  const [deleteId, setDeleteId] = useState<number | null>(null)
+
+  const filter: FilamentFilter = useMemo(() => ({
+    material: material || undefined,
+    finish: finish || undefined,
+    low_stock: lowStockOnly,
+    sort_by: sortBy,
+    sort_dir: sortDir,
+    limit: PAGE_SIZE,
+    offset: page * PAGE_SIZE,
+  }), [material, finish, lowStockOnly, sortBy, sortDir, page])
+
+  const { data, isLoading, error, refetch } = useQuery({
+    queryKey: ['filaments', filter],
+    queryFn: () => fetchFilaments(filter),
+  })
+
+  const filaments = data?.data ?? []
+  const total = data?.total ?? 0
+  const totalPages = Math.max(1, Math.ceil(total / PAGE_SIZE))
+
+  // Client-side search filter (name/barcode) since backend may not support it yet.
+  const filtered = useMemo(() => {
+    if (!search.trim()) return filaments
+    const q = search.toLowerCase()
+    return filaments.filter(
+      (f: FilamentSpool) =>
+        f.name.toLowerCase().includes(q) ||
+        (f.barcode && f.barcode.toLowerCase().includes(q))
+    )
+  }, [filaments, search])
+
+  const handleSort = (field: SortField) => {
+    if (sortBy === field) {
+      setSortDir(prev => (prev === 'asc' ? 'desc' : 'asc'))
+    } else {
+      setSortBy(field)
+      setSortDir('asc')
+    }
+    setPage(0)
+  }
+
+  const handleDelete = async (id: number) => {
+    await deleteFilament(id)
+    setDeleteId(null)
+    refetch()
+  }
+
+  const SortIndicator = ({ field }: { field: SortField }) => {
+    if (sortBy !== field) return <span className="text-slate-600 ml-1">↕</span>
+    return <span className="text-emerald-400 ml-1">{sortDir === 'asc' ? '↑' : '↓'}</span>
+  }
+
+  return (
+    <div className="space-y-4">
+      {/* Header */}
+      <div className="flex flex-col sm:flex-row sm:items-center sm:justify-between gap-3">
+        <div>
+          <h2 className="text-xl font-bold text-slate-100">Filament Inventory</h2>
+          <p className="text-sm text-slate-400">{total} spool(s) total</p>
+        </div>
+        <button className="inline-flex items-center gap-2 rounded-lg bg-emerald-600 px-4 py-2 text-sm font-semibold text-white hover:bg-emerald-500 active:bg-emerald-700 transition-colors">
+          <Plus size={16} /> Add Spool
+        </button>
+      </div>
+
+      {/* Filters */}
+      <div className="flex flex-col lg:flex-row gap-3">
+        {/* Search */}
+        <div className="relative flex-1">
+          <Search size={16} className="absolute left-3 top-1/2 -translate-y-1/2 text-slate-400" />
+          <input
+            type="text"
+            placeholder="Search by name or barcode…"
+            value={search}
+            onChange={e => { setSearch(e.target.value); setPage(0) }}
+            className="w-full rounded-lg bg-slate-800 border border-slate-700 pl-9 pr-3 py-2 text-sm text-slate-100 placeholder-slate-500 focus:outline-none focus:ring-2 focus:ring-emerald-500 focus:border-emerald-500"
+          />
+        </div>
+
+        {/* Material filter */}
+        <select
+          value={material}
+          onChange={e => { setMaterial(e.target.value); setPage(0) }}
+          className="rounded-lg bg-slate-800 border border-slate-700 px-3 py-2 text-sm text-slate-100 focus:outline-none focus:ring-2 focus:ring-emerald-500"
+        >
+          <option value="">All Materials</option>
+          <option value="PLA">PLA</option>
+          <option value="PETG">PETG</option>
+          <option value="ABS">ABS</option>
+          <option value="TPU">TPU</option>
+          <option value="ASA">ASA</option>
+          <option value="Nylon">Nylon</option>
+          <option value="PC">PC</option>
+        </select>
+
+        {/* Finish filter */}
+        <select
+          value={finish}
+          onChange={e => { setFinish(e.target.value); setPage(0) }}
+          className="rounded-lg bg-slate-800 border border-slate-700 px-3 py-2 text-sm text-slate-100 focus:outline-none focus:ring-2 focus:ring-emerald-500"
+        >
+          <option value="">All Finishes</option>
+          <option value="Basic">Basic</option>
+          <option value="Silk">Silk</option>
+          <option value="Matte">Matte</option>
+          <option value="Glossy">Glossy</option>
+          <option value="Wood">Wood</option>
+          <option value="Marble">Marble</option>
+        </select>
+
+        {/* Low stock toggle */}
+        <label className="inline-flex items-center gap-2 rounded-lg bg-slate-800 border border-slate-700 px-3 py-2 text-sm text-slate-100 cursor-pointer select-none hover:bg-slate-750">
+          <Filter size={14} className="text-amber-400" />
+          <input
+            type="checkbox"
+            checked={lowStockOnly}
+            onChange={e => { setLowStockOnly(e.target.checked); setPage(0) }}
+            className="accent-amber-500"
+          />
+          Low Stock Only
+        </label>
+      </div>
+
+      {/* Loading / Error */}
+      {isLoading && (
+        <div className="text-center py-12 text-slate-400">Loading spools…</div>
+      )}
+      {error && (
+        <div className="text-center py-12 text-red-400">
+          Failed to load inventory.
+          <button onClick={() => refetch()} className="ml-2 underline hover:text-red-300">Retry</button>
+        </div>
+      )}
+
+      {/* Desktop Table */}
+      {!isLoading && !error && (
+        <>
+          <div className="hidden md:block overflow-x-auto rounded-lg border border-slate-700">
+            <table className="w-full text-sm">
+              <thead className="bg-slate-800 text-slate-300">
+                <tr>
+                  <th className="px-4 py-3 text-left font-semibold cursor-pointer select-none hover:text-slate-100" onClick={() => handleSort('name')}>
+                    Name <SortIndicator field="name" />
+                  </th>
+                  <th className="px-4 py-3 text-left font-semibold">Material</th>
+                  <th className="px-4 py-3 text-left font-semibold">Finish</th>
+                  <th className="px-4 py-3 text-left font-semibold">Color</th>
+                  <th className="px-4 py-3 text-right font-semibold cursor-pointer select-none hover:text-slate-100" onClick={() => handleSort('remaining_grams')}>
+                    Remaining <SortIndicator field="remaining_grams" />
+                  </th>
+                  <th className="px-4 py-3 text-right font-semibold cursor-pointer select-none hover:text-slate-100" onClick={() => handleSort('cost_usd')}>
+                    Cost <SortIndicator field="cost_usd" />
+                  </th>
+                  <th className="px-4 py-3 text-center font-semibold">Status</th>
+                  <th className="px-4 py-3 text-right font-semibold">Actions</th>
+                </tr>
+              </thead>
+              <tbody className="divide-y divide-slate-700">
+                {filtered.length === 0 && (
+                  <tr>
+                    <td colSpan={8} className="px-4 py-8 text-center text-slate-500">No spools found.</td>
+                  </tr>
+                )}
+                {filtered.map((spool: FilamentSpool) => {
+                  const isLow = spool.remaining_grams <= spool.low_stock_threshold_grams
+                  return (
+                    <tr key={spool.id} className={`${isLow ? 'bg-red-900/20' : 'bg-slate-800/50'} hover:bg-slate-700/50 transition-colors`}>
+                      <td className="px-4 py-3 font-medium text-slate-100">{spool.name}</td>
+                      <td className="px-4 py-3 text-slate-300">{spool.material_base?.name ?? '—'}</td>
+                      <td className="px-4 py-3 text-slate-300">{spool.material_finish?.name ?? '—'}</td>
+                      <td className="px-4 py-3">
+                        <div className="flex items-center gap-2">
+                          <ColorSwatch colorHex={spool.color_hex} size={20} />
+                          <span className="text-xs text-slate-400 uppercase">{spool.color_hex}</span>
+                        </div>
+                      </td>
+                      <td className="px-4 py-3 text-right tabular-nums text-slate-200">{spool.remaining_grams.toLocaleString()} g</td>
+                      <td className="px-4 py-3 text-right tabular-nums text-slate-300">{spool.cost_usd != null ? `$${spool.cost_usd.toFixed(2)}` : '—'}</td>
+                      <td className="px-4 py-3 text-center">
+                        {isLow ? (
+                          <span className="inline-flex items-center gap-1 rounded-full bg-red-900/50 border border-red-700 px-2 py-0.5 text-xs font-medium text-red-300">
+                            <AlertTriangle size={12} /> Low
+                          </span>
+                        ) : (
+                          <span className="inline-flex items-center rounded-full bg-emerald-900/30 border border-emerald-700 px-2 py-0.5 text-xs font-medium text-emerald-300">OK</span>
+                        )}
+                      </td>
+                      <td className="px-4 py-3 text-right">
+                        <div className="flex items-center justify-end gap-2">
+                          <button className="p-1.5 rounded hover:bg-slate-600 text-slate-400 hover:text-blue-400 transition-colors" title="Edit">
+                            <Pencil size={14} />
+                          </button>
+                          <button
+                            onClick={() => setDeleteId(spool.id)}
+                            className="p-1.5 rounded hover:bg-slate-600 text-slate-400 hover:text-red-400 transition-colors"
+                            title="Delete"
+                          >
+                            <Trash2 size={14} />
+                          </button>
+                        </div>
+                      </td>
+                    </tr>
+                  )
+                })}
+              </tbody>
+            </table>
+          </div>
+
+          {/* Mobile Cards */}
+          <div className="md:hidden space-y-3">
+            {filtered.length === 0 && (
+              <div className="text-center py-12 text-slate-500">No spools found.</div>
+            )}
+            {filtered.map((spool: FilamentSpool) => {
+              const isLow = spool.remaining_grams <= spool.low_stock_threshold_grams
+              return (
+                <div key={spool.id} className={`rounded-lg border ${isLow ? 'border-red-700 bg-red-900/10' : 'border-slate-700 bg-slate-800'} p-4 space-y-2`}>
+                  <div className="flex items-start justify-between">
+                    <div>
+                      <div className="font-semibold text-slate-100">{spool.name}</div>
+                      <div className="text-xs text-slate-400 mt-0.5">{spool.material_base?.name ?? '—'} · {spool.material_finish?.name ?? '—'}</div>
+                    </div>
+                    {isLow ? (
+                      <span className="inline-flex items-center gap-1 rounded-full bg-red-900/50 border border-red-700 px-2 py-0.5 text-xs font-medium text-red-300">
+                        <AlertTriangle size={12} /> Low
+                      </span>
+                    ) : (
+                      <span className="inline-flex items-center rounded-full bg-emerald-900/30 border border-emerald-700 px-2 py-0.5 text-xs font-medium text-emerald-300">OK</span>
+                    )}
+                  </div>
+
+                  <div className="flex items-center gap-3 text-sm">
+                    <div className="flex items-center gap-2">
+                      <ColorSwatch colorHex={spool.color_hex} size={20} />
+                      <span className="text-slate-400 uppercase text-xs">{spool.color_hex}</span>
+                    </div>
+                  </div>
+
+                  <div className="flex items-center justify-between text-sm">
+                    <span className="text-slate-400">Remaining: <span className="text-slate-200 font-medium tabular-nums">{spool.remaining_grams.toLocaleString()} g</span></span>
+                    <span className="text-slate-400">{spool.cost_usd != null ? `$${spool.cost_usd.toFixed(2)}` : '—'}</span>
+                  </div>
+
+                  <div className="flex items-center justify-end gap-2 pt-1">
+                    <button className="flex items-center gap-1 rounded-md bg-slate-700 px-3 py-1.5 text-xs font-medium text-slate-200 hover:bg-slate-600">
+                      <Pencil size={12} /> Edit
+                    </button>
+                    <button
+                      onClick={() => setDeleteId(spool.id)}
+                      className="flex items-center gap-1 rounded-md bg-red-900/30 border border-red-700 px-3 py-1.5 text-xs font-medium text-red-300 hover:bg-red-900/50"
+                    >
+                      <Trash2 size={12} /> Delete
+                    </button>
+                  </div>
+                </div>
+              )
+            })}
+          </div>
+
+          {/* Pagination */}
+          <div className="flex items-center justify-between pt-2">
+            <span className="text-sm text-slate-400">
+              Showing {page * PAGE_SIZE + 1}–{Math.min((page + 1) * PAGE_SIZE, total)} of {total}
+            </span>
+            <div className="flex items-center gap-2">
+              <button
+                onClick={() => setPage(p => Math.max(0, p - 1))}
+                disabled={page === 0}
+                className="p-2 rounded-lg bg-slate-800 border border-slate-700 text-slate-300 hover:bg-slate-700 disabled:opacity-40 disabled:cursor-not-allowed transition-colors"
+              >
+                <ChevronLeft size={16} />
+              </button>
+              <span className="text-sm text-slate-300 tabular-nums">{page + 1} / {totalPages}</span>
+              <button
+                onClick={() => setPage(p => Math.min(totalPages - 1, p + 1))}
+                disabled={page >= totalPages - 1}
+                className="p-2 rounded-lg bg-slate-800 border border-slate-700 text-slate-300 hover:bg-slate-700 disabled:opacity-40 disabled:cursor-not-allowed transition-colors"
+              >
+                <ChevronRight size={16} />
+              </button>
+            </div>
+          </div>
+        </>
+      )}
+
+      {/* Delete confirmation modal */}
+      {deleteId !== null && (
+        <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">
+                <AlertTriangle size={20} className="text-red-400" />
+              </div>
+              <div>
+                <h3 className="text-lg font-semibold text-slate-100">Delete Spool?</h3>
+                <p className="text-sm text-slate-400">This action cannot be undone.</p>
+              </div>
+            </div>
+            <div className="flex justify-end gap-3">
+              <button
+                onClick={() => setDeleteId(null)}
+                className="rounded-lg bg-slate-700 px-4 py-2 text-sm font-medium text-slate-200 hover:bg-slate-600 transition-colors"
+              >
+                Cancel
+              </button>
+              <button
+                onClick={() => handleDelete(deleteId)}
+                className="rounded-lg bg-red-600 px-4 py-2 text-sm font-medium text-white hover:bg-red-500 transition-colors"
+              >
+                Delete
+              </button>
+            </div>
+          </div>
+        </div>
+      )}
+    </div>
+  )
+}

frontend/src/services/api.ts

@@ -1,25 +0,0 @@
-import axios from 'axios'
-
-const API_BASE_URL = import.meta.env.VITE_API_BASE_URL || 'http://localhost:8080'
-
-export const api = axios.create({
-  baseURL: API_BASE_URL,
-  headers: {
-    'Content-Type': 'application/json',
-  },
-  timeout: 10000,
-})
-
-api.interceptors.response.use(
-  (response) => response,
-  (error) => {
-    // eslint-disable-next-line no-console
-    console.error('API error:', error)
-    return Promise.reject(error)
-  }
-)
-
-export async function healthCheck(): Promise<{ status: string }> {
-  const { data } = await api.get('/health')
-  return data
-}

frontend/src/services/filamentService.ts

@@ -0,0 +1,24 @@
+import axios from 'axios'
+import type { FilamentSpool, ListResponse, FilamentFilter } from '../types/filament'
+
+const API_BASE = '/api'
+
+export async function fetchFilaments(filter: FilamentFilter): Promise<ListResponse<FilamentSpool>> {
+  const params = new URLSearchParams()
+  if (filter.material) params.set('material', filter.material)
+  if (filter.finish) params.set('finish', filter.finish)
+  if (filter.color) params.set('color', filter.color)
+  if (filter.low_stock) params.set('low_stock', 'true')
+  if (filter.search) params.set('search', filter.search)
+  if (filter.sort_by) params.set('sort_by', filter.sort_by)
+  if (filter.sort_dir) params.set('sort_dir', filter.sort_dir)
+  if (filter.limit !== undefined) params.set('limit', String(filter.limit))
+  if (filter.offset !== undefined) params.set('offset', String(filter.offset))
+
+  const res = await axios.get<ListResponse<FilamentSpool>>(`${API_BASE}/filaments?${params.toString()}`)
+  return res.data
+}
+
+export async function deleteFilament(id: number): Promise<void> {
+  await axios.delete(`${API_BASE}/filaments/${id}`)
+}

frontend/src/types/filament.ts

@@ -0,0 +1,72 @@
+// Extrudex domain types
+
+export interface MaterialBase {
+  id: number
+  name: string
+  density_g_cm3: number
+  extrusion_temp_min?: number
+  extrusion_temp_max?: number
+  bed_temp_min?: number
+  bed_temp_max?: number
+  created_at: string
+  updated_at: string
+}
+
+export interface MaterialFinish {
+  id: number
+  name: string
+  description?: string
+  created_at: string
+  updated_at: string
+}
+
+export interface MaterialModifier {
+  id: number
+  name: string
+  description?: string
+  created_at: string
+  updated_at: string
+}
+
+export interface FilamentSpool {
+  id: number
+  name: string
+  material_base_id: number
+  material_base?: MaterialBase
+  material_finish_id: number
+  material_finish?: MaterialFinish
+  material_modifier_id?: number
+  material_modifier?: MaterialModifier
+  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
+  deleted_at?: string
+  created_at: string
+  updated_at: string
+}
+
+export interface ListResponse<T> {
+  data: T[]
+  total: number
+  limit: number
+  offset: number
+}
+
+export interface FilamentFilter {
+  material?: string
+  finish?: string
+  color?: string
+  low_stock?: boolean
+  search?: string
+  sort_by?: string
+  sort_dir?: 'asc' | 'desc'
+  limit?: number
+  offset?: number
+}

frontend/src/types/index.ts

@@ -1,6 +0,0 @@
-// Shared TypeScript types for Extrudex frontend
-// Placeholder — expand as API contracts stabilize
-
-export interface HealthResponse {
-  status: string
-}

frontend/src/vite-env.d.ts

@@ -1,9 +1 @@
 /// <reference types="vite/client" />
-
-interface ImportMetaEnv {
-  readonly VITE_API_BASE_URL: string
-}
-
-interface ImportMeta {
-  readonly env: ImportMetaEnv
-}

frontend/tailwind.config.js

@@ -5,13 +5,7 @@ export default {
     "./src/**/*.{js,ts,jsx,tsx}",
   ],
   theme: {
-    extend: {
+    extend: {},
-      colors: {
-        slate: {
-          850: '#1e293b',
-        },
-      },
-    },
   },
   plugins: [],
 }

frontend/tsconfig.app.json

@@ -1,38 +1,24 @@
 {
   "compilerOptions": {
-    "tsBuildInfoFile": "./node_modules/.tmp/tsconfig.app.tsbuildinfo",
+    "target": "ES2020",
-    "target": "ES2023",
+    "useDefineForClassFields": true,
-    "lib": ["ES2023", "DOM", "DOM.Iterable"],
+    "lib": ["ES2020", "DOM", "DOM.Iterable"],
     "module": "ESNext",
-    "types": ["vite/client"],
     "skipLibCheck": true,
-
-    /* Bundler mode */
     "moduleResolution": "bundler",
     "allowImportingTsExtensions": true,
-    "verbatimModuleSyntax": true,
+    "isolatedModules": true,
     "moduleDetection": "force",
     "noEmit": true,
     "jsx": "react-jsx",
-
+    "strict": true,
-    /* Linting */
     "noUnusedLocals": true,
     "noUnusedParameters": true,
-    "erasableSyntaxOnly": true,
     "noFallthroughCasesInSwitch": true,
-
+    "baseUrl": ".",
-    /* Strict mode */
+    "paths": {
-    "strict": true,
+      "@/*": ["src/*"]
-    "noImplicitAny": true,
+    }
-    "strictNullChecks": true,
-    "strictFunctionTypes": true,
-    "strictBindCallApply": true,
-    "strictPropertyInitialization": true,
-    "noImplicitThis": true,
-    "alwaysStrict": true,
-    "noUncheckedIndexedAccess": true,
-    "exactOptionalPropertyTypes": true,
-    "noImplicitReturns": true
   },
   "include": ["src"]
 }

frontend/tsconfig.json

@@ -1,7 +1,24 @@
 {
-  "files": [],
+  "compilerOptions": {
-  "references": [
+    "target": "ES2020",
-    { "path": "./tsconfig.app.json" },
+    "useDefineForClassFields": true,
-    { "path": "./tsconfig.node.json" }
+    "lib": ["ES2020", "DOM", "DOM.Iterable"],
-  ]
+    "module": "ESNext",
+    "skipLibCheck": true,
+    "moduleResolution": "bundler",
+    "allowImportingTsExtensions": true,
+    "isolatedModules": true,
+    "moduleDetection": "force",
+    "noEmit": true,
+    "jsx": "react-jsx",
+    "strict": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "noFallthroughCasesInSwitch": true,
+    "baseUrl": ".",
+    "paths": {
+      "@/*": ["src/*"]
+    }
+  },
+  "include": ["src"]
 }

frontend/tsconfig.node.json

@@ -1,24 +1,11 @@
 {
   "compilerOptions": {
-    "tsBuildInfoFile": "./node_modules/.tmp/tsconfig.node.tsbuildinfo",
+    "composite": true,
-    "target": "es2023",
-    "lib": ["ES2023"],
-    "module": "esnext",
-    "types": ["node"],
     "skipLibCheck": true,
-
+    "module": "ESNext",
-    /* Bundler mode */
     "moduleResolution": "bundler",
-    "allowImportingTsExtensions": true,
+    "allowSyntheticDefaultImports": true,
-    "verbatimModuleSyntax": true,
+    "strict": true
-    "moduleDetection": "force",
-    "noEmit": true,
-
-    /* Linting */
-    "noUnusedLocals": true,
-    "noUnusedParameters": true,
-    "erasableSyntaxOnly": true,
-    "noFallthroughCasesInSwitch": true
   },
   "include": ["vite.config.ts"]
 }

frontend/vite.config.ts

@@ -2,15 +2,18 @@ import { defineConfig } from 'vite'
 import react from '@vitejs/plugin-react'
 import tailwindcss from '@tailwindcss/vite'
 
-// https://vite.dev/config/
 export default defineConfig({
   plugins: [react(), tailwindcss()],
   server: {
     port: 5173,
-    host: true,
+    proxy: {
+      '/api': {
+        target: 'http://localhost:8080',
+        changeOrigin: true,
+      }
+    }
   },
   build: {
     outDir: 'dist',
-    sourcemap: true,
+  }
-  },
 })