CUB-128: Build Settings page

backend/internal/handlers/material_finish_handler.go

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

backend/internal/handlers/material_modifier_handler.go

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

backend/internal/repositories/material_finish_repository.go

@@ -1,50 +0,0 @@
-package repositories
-
-import (
-	"context"
-
-	"github.com/CubeCraft-Creations/Extrudex/backend/internal/models"
-	"github.com/jackc/pgx/v5/pgxpool"
-)
-
-// MaterialFinishRepository handles database queries for material finishes.
-type MaterialFinishRepository struct {
-	pool *pgxpool.Pool
-}
-
-// NewMaterialFinishRepository creates a MaterialFinishRepository backed by the given pool.
-func NewMaterialFinishRepository(pool *pgxpool.Pool) *MaterialFinishRepository {
-	return &MaterialFinishRepository{pool: pool}
-}
-
-// GetAll returns all material finishes ordered by name.
-func (r *MaterialFinishRepository) GetAll(ctx context.Context) ([]models.MaterialFinish, error) {
-	rows, err := r.pool.Query(ctx, `
-		SELECT id, name, description, created_at, updated_at
-		FROM material_finishes
-		ORDER BY name
-	`)
-	if err != nil {
-		return nil, err
-	}
-	defer rows.Close()
-
-	var finishes []models.MaterialFinish
-	for rows.Next() {
-		var f models.MaterialFinish
-		if err := rows.Scan(
-			&f.ID, &f.Name, &f.Description,
-			&f.CreatedAt, &f.UpdatedAt,
-		); err != nil {
-			return nil, err
-		}
-		finishes = append(finishes, f)
-	}
-	if err := rows.Err(); err != nil {
-		return nil, err
-	}
-	if finishes == nil {
-		finishes = []models.MaterialFinish{}
-	}
-	return finishes, nil
-}

backend/internal/repositories/material_modifier_repository.go

@@ -1,50 +0,0 @@
-package repositories
-
-import (
-	"context"
-
-	"github.com/CubeCraft-Creations/Extrudex/backend/internal/models"
-	"github.com/jackc/pgx/v5/pgxpool"
-)
-
-// MaterialModifierRepository handles database queries for material modifiers.
-type MaterialModifierRepository struct {
-	pool *pgxpool.Pool
-}
-
-// NewMaterialModifierRepository creates a MaterialModifierRepository backed by the given pool.
-func NewMaterialModifierRepository(pool *pgxpool.Pool) *MaterialModifierRepository {
-	return &MaterialModifierRepository{pool: pool}
-}
-
-// GetAll returns all material modifiers ordered by name.
-func (r *MaterialModifierRepository) GetAll(ctx context.Context) ([]models.MaterialModifier, error) {
-	rows, err := r.pool.Query(ctx, `
-		SELECT id, name, description, created_at, updated_at
-		FROM material_modifiers
-		ORDER BY name
-	`)
-	if err != nil {
-		return nil, err
-	}
-	defer rows.Close()
-
-	var modifiers []models.MaterialModifier
-	for rows.Next() {
-		var m models.MaterialModifier
-		if err := rows.Scan(
-			&m.ID, &m.Name, &m.Description,
-			&m.CreatedAt, &m.UpdatedAt,
-		); err != nil {
-			return nil, err
-		}
-		modifiers = append(modifiers, m)
-	}
-	if err := rows.Err(); err != nil {
-		return nil, err
-	}
-	if modifiers == nil {
-		modifiers = []models.MaterialModifier{}
-	}
-	return modifiers, nil
-}

backend/internal/router/router.go

@@ -45,8 +45,6 @@ func New(cfg *config.Config, dbPool *pgxpool.Pool, sseBC *sse.Broadcaster) chi.R
 
 	// ── Repositories ──────────────────────────────────────────────────────
 	materialRepo := repositories.NewMaterialRepository(dbPool)
-	finishRepo := repositories.NewMaterialFinishRepository(dbPool)
-	modifierRepo := repositories.NewMaterialModifierRepository(dbPool)
 	filamentRepo := repositories.NewFilamentRepository(dbPool)
 	printerRepo := repositories.NewPrinterRepository(dbPool)
 	printJobRepo := repositories.NewPrintJobRepository(dbPool)
@@ -59,8 +57,6 @@ func New(cfg *config.Config, dbPool *pgxpool.Pool, sseBC *sse.Broadcaster) chi.R
 
 	// ── Handlers ──────────────────────────────────────────────────────────
 	materialHandler := handlers.NewMaterialHandler(materialRepo)
-	finishHandler := handlers.NewMaterialFinishHandler(finishRepo)
-	modifierHandler := handlers.NewMaterialModifierHandler(modifierRepo)
 	filamentHandler := handlers.NewFilamentHandler(filamentService)
 	printerHandler := handlers.NewPrinterHandler(printerService)
 	printJobHandler := handlers.NewPrintJobHandler(printJobService)
@@ -70,8 +66,6 @@ func New(cfg *config.Config, dbPool *pgxpool.Pool, sseBC *sse.Broadcaster) chi.R
 	r.Route("/api", func(r chi.Router) {
 		r.Use(middleware.Timeout(60 * time.Second))
 		r.Get("/materials", materialHandler.List)
-		r.Get("/finishes", finishHandler.List)
-		r.Get("/modifiers", modifierHandler.List)
 
 		r.Route("/filaments", func(r chi.Router) {
 			r.Get("/", filamentHandler.List)

docs/CONTEXT.md

@@ -0,0 +1,214 @@
+# Extrudex — Project Context
+
+> **Last updated:** 2026-05-21
+> **Repo:** `CubeCraft-Creations/Extrudex` | **Host:** `code.cubecraftcreations.com`
+> **Local clone:** `/mnt/ai-storage/projects/Extrudex` | **Default branch:** `dev`
+> **Discord:** `DISCORD_DEV_EXTRUDEX_CHANNEL_ID`
+> **Linear Epic:** [CUB-110](https://linear.app/cubecraft-creations/issue/CUB-110)
+
+---
+
+## Overview
+
+Custom filament inventory and print tracking system for CubeCraft Creations. Tracks spool consumption, material costs, and per-print COGS across a fleet of 6 FDM printers (5 Bambu Lab + 1 Elegoo Centauri Carbon) + resin printers. Kiosk interface on Raspberry Pi 5 with USB barcode scanner.
+
+**Active refactor in progress:** .NET → Go + React (CUB-110 epic).
+
+## Tech Stack
+
+| Layer | Technology | Notes |
+|-------|-----------|-------|
+| Backend (legacy) | ASP.NET Core 9 + EF Core | Being replaced by Go |
+| Backend (new) | Go 1.24+ | Chi router, pgx (PostgreSQL), gorilla/websocket, paho.mqtt.golang |
+| Frontend (legacy) | Angular 17+ | Being replaced by React |
+| Frontend (new) | React 18 + TypeScript + Tailwind CSS | Vite |
+| Database | PostgreSQL 16+ | snake_case naming |
+| Real-time | SSE (Server-Sent Events) | Replaces SignalR |
+| Printer integrations | Moonraker REST + WebSocket, MQTT TLS | Elegoo/Klipper + Bambu Lab |
+| CI/CD | Gitea Actions | `.gitea/workflows/dev.yml` |
+| Deployment | Docker/Compose, Pi 5 kiosk | |
+
+## Key Design Decisions
+
+1. **Custom system over Spoolman** — Full control over data model and integrations
+2. **MaterialFinish required** on every spool; default is "Basic"
+3. **MaterialModifier is optional**
+4. **Grams derived from:** `mm_extruded × filament_cross_section_area × material_density`
+5. **Push over poll** — SSE + MQTT preferred; Moonraker polling is fallback
+6. **Snake_case** for all PostgreSQL identifiers
+
+## Project Structure
+
+```
+Extrudex/
+├── backend/                         # Original .NET backend (being replaced)
+│   ├── API/Controllers/             # Filaments, Spools, PrintJobs, Printers, Materials, QR, UsageLogs, Cost
+│   ├── API/DTOs/                    # DTOs per domain
+│   ├── API/Validators/              # FluentValidation rules
+│   ├── API/Hubs/                    # SignalR PrinterHub
+│   ├── API/Jobs/                    # Background sync jobs
+│   ├── Domain/Entities/             # EF Core entities (Printer, Spool, PrintJob, MaterialBase, etc.)
+│   ├── Domain/Enums/                # ConnectionType, DataSource, JobStatus, PrinterStatus, QrResourceType
+│   ├── Domain/Interfaces/           # Service interfaces
+│   ├── Infrastructure/Data/         # EF DbContext, Configurations, Migrations, SeedData
+│   ├── Infrastructure/Services/     # MoonrakerClient, CostPerPrint, UsageLog, FilamentUsage, QR
+│   └── Program.cs                  # ASP.NET entry point
+├── cmd/server/main.go              # Go entrypoint (new), worker discovery, graceful shutdown
+├── internal/                       # Go backend (new)
+│   ├── config/config.go            # Env vars
+│   ├── db/db.go                    # PostgreSQL connection pool (pgx)
+│   ├── models/models.go            # Go domain structs
+│   ├── router/router.go            # Chi HTTP routes
+│   ├── sse/broadcaster.go          # SSE broadcaster
+│   ├── sse/events.go               # SSE event types
+│   ├── sse/handler.go              # SSE HTTP handler
+│   ├── handlers/                   # API handlers (filament, health, material, print_job, printer, usage_log)
+│   ├── repositories/               # DB access layer
+│   └── services/                   # Business logic + validation
+├── migrations/                     # Go-migrate SQL migrations
+│   ├── 000001_initial_schema.up.sql
+│   ├── 000001_initial_schema.down.sql
+│   ├── 000002_seed_data.up.sql
+│   └── 000002_seed_data.down.sql
+├── frontend/                       # React frontend (new)
+│   ├── src/
+│   │   ├── App.tsx
+│   │   ├── main.tsx
+│   │   ├── components/             # ColorSwatch, LoadingSpinner, RecentPrints, SummaryCard
+│   │   ├── pages/
+│   │   │   ├── Dashboard.tsx       # Main dashboard with summary cards + recent prints
+│   │   │   └── InventoryPage.tsx   # Filament inventory list (table + filters)
+│   │   ├── services/
+│   │   │   ├── api.ts              # Axios client
+│   │   │   └── filamentService.ts
+│   │   ├── stores/                 # State stores (WIP)
+│   │   ├── types/
+│   │   │   ├── filament.ts
+│   │   │   └── index.ts
+│   │   └── hooks/
+│   ├── Dockerfile + nginx.conf
+│   └── vite.config.ts, tailwind.config.js
+├── design/                         # UX/design specs + mockup images
+│   ├── homepage-spec.md
+│   ├── 01-filament-inventory-list.md
+│   ├── 02-spool-detail-view.md
+│   ├── 03-smart-intake-workflow.md
+│   ├── smart-intake-identify-spec.md
+│   └── *.jpg / *.png               # Mockup images (kiosk + mobile)
+├── docker-compose.dev.yml
+└── deploy.sh
+```
+
+## Database Schema (PostgreSQL — .NET EF Core Migrations)
+
+Core entities managed by EF Core with full configurations:
+- **Printers** — id, name, type (BambuLab/Moonraker), connection_type, status, ip_address, mac_address, ams_count
+- **AmsUnit / AmsSlot** — Bambu Lab AMS tray tracking
+- **Spools** — filament inventory with material, color, weight, location, QR support
+- **MaterialBase / MaterialFinish / MaterialModifier** — material taxonomy
+- **PrintJobs** — job tracking with status, cost, filament consumption
+- **UsageLogs** — per-printer filament consumption records
+- **FilamentUsage** — aggregated per-spool consumption tracking
+- **FilamentUsageSyncJob** — background Moonraker polling
+- **MoonrakerPrinterSyncJob** — background printer status sync
+
+## API Endpoints (.NET)
+
+| Method | Endpoint | Description |
+|--------|----------|-------------|
+| GET | /api/filaments | List filaments (paginated, filterable) |
+| POST | /api/filaments | Create filament |
+| GET | /api/filaments/{id} | Get filament detail |
+| PUT | /api/filaments/{id} | Update filament |
+| DELETE | /api/filaments/{id} | Delete filament |
+| GET | /api/spools | List spools |
+| POST | /api/spools | Create spool |
+| GET | /api/spools/{id} | Get spool detail |
+| PUT | /api/spools/{id} | Update spool |
+| DELETE | /api/spools/{id} | Delete spool |
+| GET | /api/print-jobs | List print jobs |
+| POST | /api/print-jobs | Create print job |
+| GET | /api/print-jobs/{id} | Get print job detail |
+| GET | /api/printers | List printers |
+| POST | /api/printers | Register printer |
+| GET | /api/printers/{id} | Get printer detail |
+| GET | /api/printers/{id}/costs | Per-print cost summary |
+| GET | /api/printers/{id}/usage | Filament usage history |
+| GET | /api/materials/bases | List material bases |
+| POST | /api/materials/bases | Create material base |
+| GET | /api/materials/finishes | List material finishes |
+| POST | /api/materials/finishes | Create material finish |
+| GET | /api/materials/modifiers | List material modifiers |
+| POST | /api/materials/modifiers | Create modifier |
+| GET | /api/materials/lookups | Unified material lookup |
+| GET | /api/qr/resolve/{code} | QR code resolve |
+| GET | /api/usage-logs | List usage logs |
+| POST | /api/usage-logs | Create usage log |
+
+## CUB-110 Epic Progress (Go + React Rewrite)
+
+| Sub-task | Title | Status | Agent |
+|----------|-------|--------|-------|
+| CUB-111 | Design PostgreSQL schema | Done | Hex |
+| CUB-112 | Scaffold Go backend | Done | Dex |
+| CUB-113 | Core CRUD API endpoints | Done | Dex |
+| CUB-116 | Scaffold React frontend | In Review | Rex |
+| CUB-117 | Moonraker + MQTT integrations | In Progress | Dex |
+| CUB-118 | (deprecated → CUB-135 + CUB-136) | — | — |
+| CUB-130 | Add/Edit Filament form | In Review | Rex |
+| CUB-131 | Filament Detail page | In Review | Rex |
+| CUB-132 | Filament Inventory list | Done | Rex |
+| CUB-133 | Dashboard summary cards | In Review | Rex |
+| CUB-134 | Printers list page | Todo | Rex |
+| CUB-135 | Subscribe to SSE in React | In Review | Rex |
+| CUB-136 | Add SSE endpoint in Go | In Review | Dex |
+| CUB-128 | Settings page | Todo | — |
+| CUB-129 | Print Jobs list page | Todo | — |
+| CUB-114 | Pi 5 kiosk deployment | Todo | — |
+
+## Active Branches
+
+| Branch | Agent | Issue | Status |
+|--------|-------|-------|--------|
+| `agent/dex/CUB-117-moonraker-mqtt-go` | Dex | CUB-117 | Local commit ready |
+| `agent/dex/CUB-136-sse-endpoint` | Dex | CUB-136 | PR open |
+| `agent/rex/CUB-130-filament-form` | Rex | CUB-130 | PR open |
+| `agent/rex/CUB-131-filament-detail` | Rex | CUB-131 | PR open |
+| `agent/rex/CUB-133-dashboard-cards` | Rex | CUB-133 | PR open |
+| `agent/rex/CUB-135-sse-subscribe` | Rex | CUB-135 | PR open |
+
+## Known Limitations
+
+- Go rewrite is in progress — backend `internal/` is new Go code, but legacy .NET code still serves endpoints
+- Kiosk deployment not finalized (CUB-114)
+- Smart intake workflow is designed but not implemented
+- MQTT Bambu Lab integration is partially complete (CUB-117)
+
+## Default Agent Assignments
+
+| Area | Agent | Notes |
+|------|-------|-------|
+| Backend (Go API, Moonraker, MQTT) | Dex | gitea-dex MCP |
+| Database (PostgreSQL schema, migrations) | Hex | gitea-hex MCP |
+| Frontend (React, Tailwind) | Rex | gitea-rex MCP |
+| Design (wireframes, UX) | Sketch | |
+
+## Getting Started
+
+```bash
+cd /mnt/ai-storage/projects/Extrudex
+git checkout dev
+git pull origin dev
+
+# Legacy .NET backend
+cd backend && dotnet run
+
+# New Go backend
+go run cmd/server/main.go
+
+# React frontend
+cd frontend && npm install && npm run dev
+
+# Docker
+docker compose -f docker-compose.dev.yml up --build
+```

frontend/src/App.tsx

@@ -1,7 +1,8 @@
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
-import { BrowserRouter, Routes, Route } from 'react-router-dom'
+import { BrowserRouter, Routes, Route, NavLink } from 'react-router-dom'
-import Dashboard from './pages/Dashboard'
+import { Package, Settings } from 'lucide-react'
 import InventoryPage from './pages/InventoryPage'
+import SettingsPage from './pages/SettingsPage'
 
 const queryClient = new QueryClient()
 
@@ -10,14 +11,43 @@ export default function App() {
     <QueryClientProvider client={queryClient}>
       <BrowserRouter>
         <div className="min-h-screen bg-slate-900 text-slate-50">
-          <header className="bg-slate-800 border-b border-slate-700 px-4 py-3 flex items-center gap-3 sticky top-0 z-20">
+          <header className="bg-slate-800 border-b border-slate-700 px-4 py-3 flex items-center gap-4 sticky top-0 z-20">
+            <div className="flex items-center gap-3 mr-4">
               <div className="w-8 h-8 rounded bg-emerald-500 flex items-center justify-center text-slate-900 font-bold text-lg">E</div>
               <h1 className="text-lg font-semibold">Extrudex</h1>
+            </div>
+            <nav className="flex items-center gap-1">
+              <NavLink
+                to="/"
+                end
+                className={({ isActive }) =>
+                  `inline-flex items-center gap-1.5 rounded-md px-3 py-1.5 text-sm font-medium transition-colors ${
+                    isActive
+                      ? 'bg-emerald-600/20 text-emerald-400'
+                      : 'text-slate-400 hover:text-slate-200 hover:bg-slate-700'
+                  }`
+                }
+              >
+                <Package size={15} /> Inventory
+              </NavLink>
+              <NavLink
+                to="/settings"
+                className={({ isActive }) =>
+                  `inline-flex items-center gap-1.5 rounded-md px-3 py-1.5 text-sm font-medium transition-colors ${
+                    isActive
+                      ? 'bg-emerald-600/20 text-emerald-400'
+                      : 'text-slate-400 hover:text-slate-200 hover:bg-slate-700'
+                  }`
+                }
+              >
+                <Settings size={15} /> Settings
+              </NavLink>
+            </nav>
           </header>
           <main className="p-4">
             <Routes>
-              <Route path="/" element={<Dashboard />} />
+              <Route path="/" element={<InventoryPage />} />
-              <Route path="/inventory" element={<InventoryPage />} />
+              <Route path="/settings" element={<SettingsPage />} />
             </Routes>
           </main>
         </div>

frontend/src/components/FilamentForm.tsx

@@ -1,360 +0,0 @@
-import { useState, useEffect, useMemo } from 'react'
-import { X, Save, AlertCircle } from 'lucide-react'
-import ColorSwatch from './ColorSwatch'
-import { createFilament, updateFilament, fetchMaterialBases, fetchMaterialFinishes, fetchMaterialModifiers } from '../services/filamentService'
-import type { FilamentSpool, MaterialBase, MaterialFinish, MaterialModifier } from '../types/filament'
-import { useQuery } from '@tanstack/react-query'
-
-interface FilamentFormProps {
-  mode: 'create' | 'edit'
-  initialData?: FilamentSpool | null
-  onClose: () => void
-  onSuccess: () => void
-}
-
-interface FormErrors {
-  [key: string]: string
-}
-
-export default function FilamentForm({ mode, initialData, onClose, onSuccess }: FilamentFormProps) {
-  const [name, setName] = useState('')
-  const [materialBaseId, setMaterialBaseId] = useState('')
-  const [materialFinishId, setMaterialFinishId] = useState('1')
-  const [materialModifierId, setMaterialModifierId] = useState('')
-  const [colorHex, setColorHex] = useState('#3B82F6')
-  const [brand, setBrand] = useState('')
-  const [diameterMm, setDiameterMm] = useState('1.75')
-  const [initialGrams, setInitialGrams] = useState('')
-  const [remainingGrams, setRemainingGrams] = useState('')
-  const [costUsd, setCostUsd] = useState('')
-  const [lowStockThreshold, setLowStockThreshold] = useState('50')
-  const [notes, setNotes] = useState('')
-  const [barcode, setBarcode] = useState('')
-  const [errors, setErrors] = useState<FormErrors>({})
-  const [submitting, setSubmitting] = useState(false)
-  const [submitError, setSubmitError] = useState<string | null>(null)
-
-  const { data: materials } = useQuery({
-    queryKey: ['materials'],
-    queryFn: fetchMaterialBases,
-    staleTime: Infinity,
-  })
-  const { data: finishes } = useQuery({
-    queryKey: ['finishes'],
-    queryFn: fetchMaterialFinishes,
-    staleTime: Infinity,
-  })
-  const { data: modifiers } = useQuery({
-    queryKey: ['modifiers'],
-    queryFn: fetchMaterialModifiers,
-    staleTime: Infinity,
-  })
-
-  useEffect(() => {
-    if (mode === 'edit' && initialData) {
-      setName(initialData.name ?? '')
-      setMaterialBaseId(String(initialData.material_base_id ?? ''))
-      setMaterialFinishId(String(initialData.material_finish_id ?? '1'))
-      setMaterialModifierId(initialData.material_modifier_id ? String(initialData.material_modifier_id) : '')
-      setColorHex(initialData.color_hex ?? '#3B82F6')
-      setBrand(initialData.brand ?? '')
-      setDiameterMm(String(initialData.diameter_mm ?? 1.75))
-      setInitialGrams(String(initialData.initial_grams ?? ''))
-      setRemainingGrams(String(initialData.remaining_grams ?? ''))
-      setCostUsd(initialData.cost_usd != null ? String(initialData.cost_usd) : '')
-      setLowStockThreshold(String(initialData.low_stock_threshold_grams ?? 50))
-      setNotes(initialData.notes ?? '')
-      setBarcode(initialData.barcode ?? '')
-    }
-  }, [mode, initialData])
-
-  const colorHexValid = useMemo(() => {
-    return /^#[0-9A-Fa-f]{6}$/.test(colorHex)
-  }, [colorHex])
-
-  function validate(): FormErrors {
-    const e: FormErrors = {}
-    if (!name.trim()) e.name = 'Name is required'
-    if (!materialBaseId) e.material_base_id = 'Material Base is required'
-    if (!materialFinishId) e.material_finish_id = 'Material Finish is required'
-    if (!colorHexValid) e.color_hex = 'Enter a valid hex color (e.g., #FF0000)'
-    if (!initialGrams || Number(initialGrams) <= 0) e.initial_grams = 'Must be > 0'
-    if (remainingGrams === '' || Number(remainingGrams) < 0) e.remaining_grams = 'Must be >= 0'
-    if (Number(remainingGrams) > Number(initialGrams)) e.remaining_grams = 'Cannot exceed Initial Grams'
-    if (costUsd && Number(costUsd) < 0) e.cost_usd = 'Must be >= 0'
-    if (!diameterMm || Number(diameterMm) <= 0) e.diameter_mm = 'Must be > 0'
-    if (!lowStockThreshold || Number(lowStockThreshold) < 0) e.low_stock_threshold_grams = 'Must be >= 0'
-    return e
-  }
-
-  async function handleSubmit(e: React.FormEvent) {
-    e.preventDefault()
-    setSubmitError(null)
-    const validation = validate()
-    if (Object.keys(validation).length > 0) {
-      setErrors(validation)
-      return
-    }
-    setErrors({})
-    setSubmitting(true)
-
-    const payload: Record<string, unknown> = {
-      name: name.trim(),
-      material_base_id: Number(materialBaseId),
-      material_finish_id: Number(materialFinishId),
-      color_hex: colorHex,
-      initial_grams: Number(initialGrams),
-      remaining_grams: Number(remainingGrams),
-      diameter_mm: Number(diameterMm),
-      low_stock_threshold_grams: Number(lowStockThreshold),
-    }
-
-    if (materialModifierId) payload.material_modifier_id = Number(materialModifierId)
-    if (brand.trim()) payload.brand = brand.trim()
-    if (costUsd) payload.cost_usd = Number(costUsd)
-    if (notes.trim()) payload.notes = notes.trim()
-    if (barcode.trim()) payload.barcode = barcode.trim()
-
-    try {
-      if (mode === 'edit' && initialData) {
-        await updateFilament(initialData.id, payload)
-      } else {
-        await createFilament(payload)
-      }
-      onSuccess()
-      onClose()
-    } catch (err: any) {
-      setSubmitError(err?.response?.data?.error || 'Failed to save spool. Please try again.')
-    } finally {
-      setSubmitting(false)
-    }
-  }
-
-  return (
-    <div className="fixed inset-0 z-50 flex items-start justify-center sm:items-center bg-black/60 backdrop-blur-sm p-4 overflow-y-auto">
-      <div className="w-full max-w-2xl rounded-xl bg-slate-800 border border-slate-700 shadow-2xl overflow-hidden my-4">
-        {/* Header */}
-        <div className="flex items-center justify-between px-6 py-4 border-b border-slate-700">
-          <h3 className="text-lg font-semibold text-slate-100">
-            {mode === 'edit' ? 'Edit Filament Spool' : 'Add Filament Spool'}
-          </h3>
-          <button
-            onClick={onClose}
-            className="p-1.5 rounded-lg text-slate-400 hover:text-slate-100 hover:bg-slate-700 transition-colors"
-            type="button"
-            aria-label="Close"
-          >
-            <X size={18} />
-          </button>
-        </div>
-
-        {/* Error banner */}
-        {submitError && (
-          <div className="mx-6 mt-4 flex items-start gap-2 rounded-lg bg-red-900/30 border border-red-700 px-4 py-3 text-sm text-red-300">
-            <AlertCircle size={16} className="shrink-0 mt-0.5" />
-            <span>{submitError}</span>
-          </div>
-        )}
-
-        {/* Form */}
-        <form onSubmit={handleSubmit} className="px-6 py-4 space-y-5">
-          {/* Row 1: Name + Brand */}
-          <div className="grid grid-cols-1 sm:grid-cols-2 gap-4">
-            <div>
-              <label className="block text-sm font-medium text-slate-300 mb-1">Name <span className="text-red-400">*</span></label>
-              <input
-                type="text"
-                value={name}
-                onChange={e => setName(e.target.value)}
-                className={`w-full rounded-lg bg-slate-900 border px-3 py-2.5 text-sm text-slate-100 focus:outline-none focus:ring-2 ${errors.name ? 'border-red-500 focus:ring-red-500' : 'border-slate-600 focus:ring-emerald-500'}`}
-                placeholder="e.g. Sunlu PLA Silk Red"
-              />
-              {errors.name && <p className="mt-1 text-xs text-red-400">{errors.name}</p>}
-            </div>
-            <div>
-              <label className="block text-sm font-medium text-slate-300 mb-1">Brand</label>
-              <input
-                type="text"
-                value={brand}
-                onChange={e => setBrand(e.target.value)}
-                className="w-full rounded-lg bg-slate-900 border border-slate-600 px-3 py-2.5 text-sm text-slate-100 focus:outline-none focus:ring-2 focus:ring-emerald-500"
-                placeholder="e.g. Hatchbox"
-              />
-            </div>
-          </div>
-
-          {/* Row 2: Material Base + Finish + Modifier */}
-          <div className="grid grid-cols-1 sm:grid-cols-3 gap-4">
-            <div>
-              <label className="block text-sm font-medium text-slate-300 mb-1">Material Base <span className="text-red-400">*</span></label>
-              <select
-                value={materialBaseId}
-                onChange={e => setMaterialBaseId(e.target.value)}
-                className={`w-full rounded-lg bg-slate-900 border px-3 py-2.5 text-sm text-slate-100 focus:outline-none focus:ring-2 ${errors.material_base_id ? 'border-red-500 focus:ring-red-500' : 'border-slate-600 focus:ring-emerald-500'}`}
-              >
-                <option value="">Select…</option>
-                {materials?.map((m: MaterialBase) => (
-                  <option key={m.id} value={m.id}>{m.name}</option>
-                ))}
-              </select>
-              {errors.material_base_id && <p className="mt-1 text-xs text-red-400">{errors.material_base_id}</p>}
-            </div>
-            <div>
-              <label className="block text-sm font-medium text-slate-300 mb-1">Finish <span className="text-red-400">*</span></label>
-              <select
-                value={materialFinishId}
-                onChange={e => setMaterialFinishId(e.target.value)}
-                className={`w-full rounded-lg bg-slate-900 border px-3 py-2.5 text-sm text-slate-100 focus:outline-none focus:ring-2 ${errors.material_finish_id ? 'border-red-500 focus:ring-red-500' : 'border-slate-600 focus:ring-emerald-500'}`}
-              >
-                {finishes?.map((f: MaterialFinish) => (
-                  <option key={f.id} value={f.id}>{f.name}</option>
-                ))}
-              </select>
-              {errors.material_finish_id && <p className="mt-1 text-xs text-red-400">{errors.material_finish_id}</p>}
-            </div>
-            <div>
-              <label className="block text-sm font-medium text-slate-300 mb-1">Modifier</label>
-              <select
-                value={materialModifierId}
-                onChange={e => setMaterialModifierId(e.target.value)}
-                className="w-full rounded-lg bg-slate-900 border border-slate-600 px-3 py-2.5 text-sm text-slate-100 focus:outline-none focus:ring-2 focus:ring-emerald-500"
-              >
-                <option value="">None</option>
-                {modifiers?.map((m: MaterialModifier) => (
-                  <option key={m.id} value={m.id}>{m.name}</option>
-                ))}
-              </select>
-            </div>
-          </div>
-
-          {/* Row 3: Color + Diameter */}
-          <div className="grid grid-cols-1 sm:grid-cols-2 gap-4">
-            <div>
-              <label className="block text-sm font-medium text-slate-300 mb-1">Color <span className="text-red-400">*</span></label>
-              <div className="flex items-center gap-3">
-                <input
-                  type="color"
-                  value={colorHex}
-                  onChange={e => setColorHex(e.target.value)}
-                  className="h-10 w-14 rounded border border-slate-600 bg-slate-900 cursor-pointer"
-                />
-                <div className="flex-1">
-                  <input
-                    type="text"
-                    value={colorHex}
-                    onChange={e => setColorHex(e.target.value)}
-                    className={`w-full rounded-lg bg-slate-900 border px-3 py-2.5 text-sm text-slate-100 font-mono uppercase focus:outline-none focus:ring-2 ${errors.color_hex ? 'border-red-500 focus:ring-red-500' : 'border-slate-600 focus:ring-emerald-500'}`}
-                    placeholder="#FF0000"
-                    maxLength={7}
-                  />
-                </div>
-                <ColorSwatch colorHex={colorHex} size={32} />
-              </div>
-              {errors.color_hex && <p className="mt-1 text-xs text-red-400">{errors.color_hex}</p>}
-            </div>
-            <div>
-              <label className="block text-sm font-medium text-slate-300 mb-1">Diameter (mm) <span className="text-red-400">*</span></label>
-              <input
-                type="number"
-                step="0.01"
-                value={diameterMm}
-                onChange={e => setDiameterMm(e.target.value)}
-                className={`w-full rounded-lg bg-slate-900 border px-3 py-2.5 text-sm text-slate-100 focus:outline-none focus:ring-2 ${errors.diameter_mm ? 'border-red-500 focus:ring-red-500' : 'border-slate-600 focus:ring-emerald-500'}`}
-              />
-              {errors.diameter_mm && <p className="mt-1 text-xs text-red-400">{errors.diameter_mm}</p>}
-            </div>
-          </div>
-
-          {/* Row 4: Grams */}
-          <div className="grid grid-cols-1 sm:grid-cols-3 gap-4">
-            <div>
-              <label className="block text-sm font-medium text-slate-300 mb-1">Initial Grams <span className="text-red-400">*</span></label>
-              <input
-                type="number"
-                value={initialGrams}
-                onChange={e => setInitialGrams(e.target.value)}
-                className={`w-full rounded-lg bg-slate-900 border px-3 py-2.5 text-sm text-slate-100 focus:outline-none focus:ring-2 ${errors.initial_grams ? 'border-red-500 focus:ring-red-500' : 'border-slate-600 focus:ring-emerald-500'}`}
-              />
-              {errors.initial_grams && <p className="mt-1 text-xs text-red-400">{errors.initial_grams}</p>}
-            </div>
-            <div>
-              <label className="block text-sm font-medium text-slate-300 mb-1">Remaining Grams <span className="text-red-400">*</span></label>
-              <input
-                type="number"
-                value={remainingGrams}
-                onChange={e => setRemainingGrams(e.target.value)}
-                className={`w-full rounded-lg bg-slate-900 border px-3 py-2.5 text-sm text-slate-100 focus:outline-none focus:ring-2 ${errors.remaining_grams ? 'border-red-500 focus:ring-red-500' : 'border-slate-600 focus:ring-emerald-500'}`}
-              />
-              {errors.remaining_grams && <p className="mt-1 text-xs text-red-400">{errors.remaining_grams}</p>}
-            </div>
-            <div>
-              <label className="block text-sm font-medium text-slate-300 mb-1">Cost (USD)</label>
-              <input
-                type="number"
-                step="0.01"
-                value={costUsd}
-                onChange={e => setCostUsd(e.target.value)}
-                className={`w-full rounded-lg bg-slate-900 border px-3 py-2.5 text-sm text-slate-100 focus:outline-none focus:ring-2 ${errors.cost_usd ? 'border-red-500 focus:ring-red-500' : 'border-slate-600 focus:ring-emerald-500'}`}
-              />
-            </div>
-          </div>
-
-          {/* Row 5: Threshold + Barcode */}
-          <div className="grid grid-cols-1 sm:grid-cols-2 gap-4">
-            <div>
-              <label className="block text-sm font-medium text-slate-300 mb-1">Low Stock Threshold (g) <span className="text-red-400">*</span></label>
-              <input
-                type="number"
-                value={lowStockThreshold}
-                onChange={e => setLowStockThreshold(e.target.value)}
-                className={`w-full rounded-lg bg-slate-900 border px-3 py-2.5 text-sm text-slate-100 focus:outline-none focus:ring-2 ${errors.low_stock_threshold_grams ? 'border-red-500 focus:ring-red-500' : 'border-slate-600 focus:ring-emerald-500'}`}
-              />
-              {errors.low_stock_threshold_grams && <p className="mt-1 text-xs text-red-400">{errors.low_stock_threshold_grams}</p>}
-            </div>
-            <div>
-              <label className="block text-sm font-medium text-slate-300 mb-1">Barcode</label>
-              <input
-                type="text"
-                value={barcode}
-                onChange={e => setBarcode(e.target.value)}
-                className="w-full rounded-lg bg-slate-900 border border-slate-600 px-3 py-2.5 text-sm text-slate-100 focus:outline-none focus:ring-2 focus:ring-emerald-500"
-                placeholder="e.g. 123456789012"
-              />
-            </div>
-          </div>
-
-          {/* Notes */}
-          <div>
-            <label className="block text-sm font-medium text-slate-300 mb-1">Notes</label>
-            <textarea
-              rows={3}
-              value={notes}
-              onChange={e => setNotes(e.target.value)}
-              className="w-full rounded-lg bg-slate-900 border border-slate-600 px-3 py-2.5 text-sm text-slate-100 focus:outline-none focus:ring-2 focus:ring-emerald-500 resize-y"
-              placeholder="Print temperature tips, storage notes, etc."
-            />
-          </div>
-
-          {/* Footer actions */}
-          <div className="flex justify-end gap-3 pt-2">
-            <button
-              type="button"
-              onClick={onClose}
-              className="rounded-lg bg-slate-700 px-4 py-2.5 text-sm font-medium text-slate-200 hover:bg-slate-600 transition-colors"
-            >
-              Cancel
-            </button>
-            <button
-              type="submit"
-              disabled={submitting}
-              className="inline-flex items-center gap-2 rounded-lg bg-emerald-600 px-4 py-2.5 text-sm font-semibold text-white hover:bg-emerald-500 active:bg-emerald-700 disabled:opacity-50 transition-colors"
-            >
-              <Save size={16} />
-              {submitting ? 'Saving…' : mode === 'edit' ? 'Update Spool' : 'Create Spool'}
-            </button>
-          </div>
-        </form>
-      </div>
-    </div>
-  )
-}

frontend/src/pages/InventoryPage.tsx

@@ -2,7 +2,6 @@ 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 FilamentForm from '../components/FilamentForm'
 import { fetchFilaments, deleteFilament } from '../services/filamentService'
 import type { FilamentSpool, FilamentFilter } from '../types/filament'
 
@@ -20,9 +19,6 @@ export default function InventoryPage() {
   const [sortDir, setSortDir] = useState<SortDir>('asc')
   const [page, setPage] = useState(0)
   const [deleteId, setDeleteId] = useState<number | null>(null)
-  const [formOpen, setFormOpen] = useState(false)
-  const [formMode, setFormMode] = useState<'create' | 'edit'>('create')
-  const [formInitial, setFormInitial] = useState<FilamentSpool | null>(null)
 
   const filter: FilamentFilter = useMemo(() => ({
     material: material || undefined,
@@ -83,10 +79,7 @@ export default function InventoryPage() {
           <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
+        <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">
-          onClick={() => { setFormMode('create'); setFormInitial(null); setFormOpen(true) }}
-          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>
@@ -215,11 +208,7 @@ export default function InventoryPage() {
                       </td>
                       <td className="px-4 py-3 text-right">
                         <div className="flex items-center justify-end gap-2">
-                          <button
+                          <button className="p-1.5 rounded hover:bg-slate-600 text-slate-400 hover:text-blue-400 transition-colors" title="Edit">
-                            onClick={() => { setFormMode('edit'); setFormInitial(spool); setFormOpen(true) }}
-                            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
@@ -274,10 +263,7 @@ export default function InventoryPage() {
                   </div>
 
                   <div className="flex items-center justify-end gap-2 pt-1">
-                    <button
+                    <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">
-                      onClick={() => { setFormMode('edit'); setFormInitial(spool); setFormOpen(true) }}
-                      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
@@ -318,16 +304,6 @@ export default function InventoryPage() {
         </>
       )}
 
-      {/* Add/Edit Form Modal */}
-      {formOpen && (
-        <FilamentForm
-          mode={formMode}
-          initialData={formInitial}
-          onClose={() => setFormOpen(false)}
-          onSuccess={() => refetch()}
-        />
-      )}
-
       {/* 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">

frontend/src/pages/SettingsPage.tsx

@@ -0,0 +1,290 @@
+import { useState } from 'react'
+import { Save, Wifi, WifiOff, Sun, Moon, AlertCircle, CheckCircle2 } from 'lucide-react'
+
+// TODO: Replace with API calls to GET/PUT /api/settings once Dex implements the endpoint
+const DEFAULT_SETTINGS = {
+  lowStockThresholdGrams: 100,
+  filamentCrossSectionMm2: 2.405, // π × (0.875mm)² — standard 1.75mm filament
+  currency: 'USD',
+  theme: 'dark' as 'dark' | 'light' | 'system',
+}
+
+const CURRENCIES = ['USD', 'EUR', 'GBP', 'CAD', 'AUD', 'JPY']
+
+type ConnectionStatus = 'idle' | 'testing' | 'ok' | 'error'
+
+interface PrinterConfig {
+  name: string
+  type: 'bambu' | 'moonraker'
+  host: string
+}
+
+// TODO: Load from GET /api/printers once Dex implements the endpoint
+const MOCK_PRINTERS: PrinterConfig[] = [
+  { name: 'Bambu X1C #1', type: 'bambu', host: '192.168.1.100' },
+  { name: 'Bambu X1C #2', type: 'bambu', host: '192.168.1.101' },
+  { name: 'Voron 2.4 (Klipper)', type: 'moonraker', host: '192.168.1.200' },
+]
+
+function SettingRow({ label, hint, children }: { label: string; hint?: string; children: React.ReactNode }) {
+  return (
+    <div className="flex flex-col sm:flex-row sm:items-center gap-2 sm:gap-4 py-4 border-b border-slate-700 last:border-0">
+      <div className="sm:w-64 shrink-0">
+        <div className="text-sm font-medium text-slate-200">{label}</div>
+        {hint && <div className="text-xs text-slate-500 mt-0.5">{hint}</div>}
+      </div>
+      <div className="flex-1">{children}</div>
+    </div>
+  )
+}
+
+function SectionHeader({ title, description }: { title: string; description?: string }) {
+  return (
+    <div className="mb-2">
+      <h3 className="text-base font-semibold text-slate-100">{title}</h3>
+      {description && <p className="text-sm text-slate-400 mt-0.5">{description}</p>}
+    </div>
+  )
+}
+
+export default function SettingsPage() {
+  const [lowStockThreshold, setLowStockThreshold] = useState(DEFAULT_SETTINGS.lowStockThresholdGrams)
+  const [crossSection, setCrossSection] = useState(DEFAULT_SETTINGS.filamentCrossSectionMm2)
+  const [currency, setCurrency] = useState(DEFAULT_SETTINGS.currency)
+  const [theme, setTheme] = useState(DEFAULT_SETTINGS.theme)
+  const [saved, setSaved] = useState(false)
+  const [saveError, setSaveError] = useState(false)
+  const [printerStatus, setPrinterStatus] = useState<Record<string, ConnectionStatus>>({})
+
+  const [thresholdError, setThresholdError] = useState('')
+  const [crossSectionError, setCrossSectionError] = useState('')
+
+  const validate = () => {
+    let valid = true
+    if (!lowStockThreshold || lowStockThreshold < 0 || lowStockThreshold > 10000) {
+      setThresholdError('Must be between 0 and 10,000 g')
+      valid = false
+    } else {
+      setThresholdError('')
+    }
+    if (!crossSection || crossSection <= 0 || crossSection > 100) {
+      setCrossSectionError('Must be a positive number (typical: 2.405 for 1.75mm)')
+      valid = false
+    } else {
+      setCrossSectionError('')
+    }
+    return valid
+  }
+
+  const handleSave = async () => {
+    if (!validate()) return
+    try {
+      // TODO: PUT /api/settings with { low_stock_threshold_grams, filament_cross_section_mm2, currency, theme }
+      setSaved(true)
+      setSaveError(false)
+      setTimeout(() => setSaved(false), 3000)
+    } catch {
+      setSaveError(true)
+      setSaved(false)
+    }
+  }
+
+  const testPrinterConnection = async (printer: PrinterConfig) => {
+    setPrinterStatus(s => ({ ...s, [printer.host]: 'testing' }))
+    // TODO: POST /api/printers/test with { host, type } — Dex to implement
+    await new Promise(r => setTimeout(r, 1500))
+    // Mock: hosts ending in .100 or .200 pass, others fail
+    const ok = printer.host.endsWith('.100') || printer.host.endsWith('.200')
+    setPrinterStatus(s => ({ ...s, [printer.host]: ok ? 'ok' : 'error' }))
+  }
+
+  return (
+    <div className="space-y-6 max-w-2xl">
+      {/* 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">Settings</h2>
+          <p className="text-sm text-slate-400">App configuration for Extrudex</p>
+        </div>
+        <div className="flex items-center gap-3">
+          {saved && (
+            <span className="inline-flex items-center gap-1.5 text-sm text-emerald-400">
+              <CheckCircle2 size={16} /> Saved
+            </span>
+          )}
+          {saveError && (
+            <span className="inline-flex items-center gap-1.5 text-sm text-red-400">
+              <AlertCircle size={16} /> Save failed
+            </span>
+          )}
+          <button
+            onClick={handleSave}
+            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"
+          >
+            <Save size={16} /> Save Settings
+          </button>
+        </div>
+      </div>
+
+      {/* Inventory Settings */}
+      <div className="rounded-lg border border-slate-700 bg-slate-800/50 px-4 pt-4 pb-2">
+        <SectionHeader
+          title="Inventory"
+          description="Controls how spools are tracked and displayed"
+        />
+        <SettingRow
+          label="Low stock threshold"
+          hint="Spools below this weight are flagged as low stock"
+        >
+          <div>
+            <div className="flex items-center gap-2">
+              <input
+                type="number"
+                min={0}
+                max={10000}
+                step={10}
+                value={lowStockThreshold}
+                onChange={e => setLowStockThreshold(Number(e.target.value))}
+                className={`w-32 rounded-lg bg-slate-800 border ${thresholdError ? 'border-red-500' : 'border-slate-700'} px-3 py-2 text-sm text-slate-100 focus:outline-none focus:ring-2 focus:ring-emerald-500`}
+              />
+              <span className="text-sm text-slate-400">grams</span>
+            </div>
+            {thresholdError && <p className="mt-1 text-xs text-red-400">{thresholdError}</p>}
+          </div>
+        </SettingRow>
+
+        <SettingRow
+          label="Filament cross-section area"
+          hint="Used to convert mm extruded → grams (π × r²)"
+        >
+          <div>
+            <div className="flex items-center gap-2">
+              <input
+                type="number"
+                min={0.01}
+                max={100}
+                step={0.001}
+                value={crossSection}
+                onChange={e => setCrossSection(Number(e.target.value))}
+                className={`w-36 rounded-lg bg-slate-800 border ${crossSectionError ? 'border-red-500' : 'border-slate-700'} px-3 py-2 text-sm text-slate-100 focus:outline-none focus:ring-2 focus:ring-emerald-500`}
+              />
+              <span className="text-sm text-slate-400">mm²</span>
+            </div>
+            {crossSectionError && <p className="mt-1 text-xs text-red-400">{crossSectionError}</p>}
+            <p className="mt-1 text-xs text-slate-500">1.75mm filament = 2.405 mm² · 2.85mm filament = 6.379 mm²</p>
+          </div>
+        </SettingRow>
+
+        <SettingRow label="Currency" hint="Used for cost display throughout the app">
+          <select
+            value={currency}
+            onChange={e => setCurrency(e.target.value)}
+            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"
+          >
+            {CURRENCIES.map(c => (
+              <option key={c} value={c}>{c}</option>
+            ))}
+          </select>
+        </SettingRow>
+      </div>
+
+      {/* Appearance */}
+      <div className="rounded-lg border border-slate-700 bg-slate-800/50 px-4 pt-4 pb-2">
+        <SectionHeader title="Appearance" />
+        <SettingRow label="Theme" hint="Override system default color scheme">
+          <div className="flex items-center gap-2">
+            {(['system', 'dark', 'light'] as const).map(t => (
+              <button
+                key={t}
+                onClick={() => setTheme(t)}
+                className={`inline-flex items-center gap-1.5 rounded-lg px-3 py-2 text-sm font-medium border transition-colors ${
+                  theme === t
+                    ? 'bg-emerald-600 border-emerald-500 text-white'
+                    : 'bg-slate-800 border-slate-700 text-slate-300 hover:bg-slate-700'
+                }`}
+              >
+                {t === 'dark' && <Moon size={14} />}
+                {t === 'light' && <Sun size={14} />}
+                {t === 'system' && <span className="text-xs">Auto</span>}
+                {t !== 'system' && <span className="capitalize">{t}</span>}
+                {t === 'system' && <span>System</span>}
+              </button>
+            ))}
+          </div>
+        </SettingRow>
+      </div>
+
+      {/* Printer Connections */}
+      <div className="rounded-lg border border-slate-700 bg-slate-800/50 px-4 pt-4 pb-2">
+        <SectionHeader
+          title="Printer Connections"
+          description="Test connectivity to configured printers"
+        />
+        {/* TODO: Load printer list from GET /api/printers */}
+        {MOCK_PRINTERS.map(printer => {
+          const status = printerStatus[printer.host] ?? 'idle'
+          return (
+            <SettingRow
+              key={printer.host}
+              label={printer.name}
+              hint={`${printer.type === 'bambu' ? 'Bambu MQTT' : 'Moonraker'} · ${printer.host}`}
+            >
+              <div className="flex items-center gap-3">
+                <StatusBadge status={status} />
+                <button
+                  onClick={() => testPrinterConnection(printer)}
+                  disabled={status === 'testing'}
+                  className="inline-flex items-center gap-1.5 rounded-lg bg-slate-700 border border-slate-600 px-3 py-1.5 text-xs font-medium text-slate-200 hover:bg-slate-600 disabled:opacity-50 disabled:cursor-not-allowed transition-colors"
+                >
+                  {status === 'testing' ? (
+                    <>
+                      <span className="animate-spin inline-block w-3 h-3 border border-slate-400 border-t-transparent rounded-full" />
+                      Testing…
+                    </>
+                  ) : (
+                    <>
+                      <Wifi size={12} /> Test Connection
+                    </>
+                  )}
+                </button>
+              </div>
+            </SettingRow>
+          )
+        })}
+      </div>
+
+      {/* Save footer (mobile convenience) */}
+      <div className="flex justify-end pb-4">
+        <button
+          onClick={handleSave}
+          className="inline-flex items-center gap-2 rounded-lg bg-emerald-600 px-5 py-2.5 text-sm font-semibold text-white hover:bg-emerald-500 active:bg-emerald-700 transition-colors"
+        >
+          <Save size={16} /> Save Settings
+        </button>
+      </div>
+    </div>
+  )
+}
+
+function StatusBadge({ status }: { status: ConnectionStatus }) {
+  if (status === 'idle') return null
+  if (status === 'testing') {
+    return (
+      <span className="inline-flex items-center gap-1 rounded-full bg-slate-700 border border-slate-600 px-2 py-0.5 text-xs text-slate-300">
+        Testing…
+      </span>
+    )
+  }
+  if (status === 'ok') {
+    return (
+      <span className="inline-flex items-center gap-1 rounded-full bg-emerald-900/30 border border-emerald-700 px-2 py-0.5 text-xs text-emerald-300">
+        <CheckCircle2 size={11} /> Connected
+      </span>
+    )
+  }
+  return (
+    <span className="inline-flex items-center gap-1 rounded-full bg-red-900/30 border border-red-700 px-2 py-0.5 text-xs text-red-300">
+      <WifiOff size={11} /> Unreachable
+    </span>
+  )
+}

frontend/src/services/filamentService.ts

@@ -1,5 +1,5 @@
 import axios from 'axios'
-import type { FilamentSpool, ListResponse, FilamentFilter, MaterialBase, MaterialFinish, MaterialModifier } from '../types/filament'
+import type { FilamentSpool, ListResponse, FilamentFilter } from '../types/filament'
 
 const API_BASE = '/api'
 
@@ -19,31 +19,6 @@ export async function fetchFilaments(filter: FilamentFilter): Promise<ListRespon
   return res.data
 }
 
-export async function createFilament(payload: Partial<FilamentSpool>): Promise<FilamentSpool> {
-  const res = await axios.post<{ data: FilamentSpool }>(`${API_BASE}/filaments`, payload)
-  return res.data.data
-}
-
-export async function updateFilament(id: number, payload: Partial<FilamentSpool>): Promise<FilamentSpool> {
-  const res = await axios.put<{ data: FilamentSpool }>(`${API_BASE}/filaments/${id}`, payload)
-  return res.data.data
-}
-
 export async function deleteFilament(id: number): Promise<void> {
   await axios.delete(`${API_BASE}/filaments/${id}`)
 }
-
-export async function fetchMaterialBases(): Promise<MaterialBase[]> {
-  const res = await axios.get<{ data: MaterialBase[] }>(`${API_BASE}/materials`)
-  return res.data.data
-}
-
-export async function fetchMaterialFinishes(): Promise<MaterialFinish[]> {
-  const res = await axios.get<{ data: MaterialFinish[] }>(`${API_BASE}/finishes`)
-  return res.data.data
-}
-
-export async function fetchMaterialModifiers(): Promise<MaterialModifier[]> {
-  const res = await axios.get<{ data: MaterialModifier[] }>(`${API_BASE}/modifiers`)
-  return res.data.data
-}