diff --git a/server/handlers/agents.go b/server/handlers/agents.go
new file mode 100644
index 0000000..47ace01
--- /dev/null
+++ b/server/handlers/agents.go
@@ -0,0 +1,20 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/user/nanometrics/server/db"
+)
+
+func AgentsHandler(database *db.DB) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		agents, err := database.GetAgents()
+		if err != nil {
+			http.Error(w, err.Error(), 500)
+			return
+		}
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(agents)
+	}
+}
diff --git a/server/handlers/config.go b/server/handlers/config.go
new file mode 100644
index 0000000..69d7fef
--- /dev/null
+++ b/server/handlers/config.go
@@ -0,0 +1,83 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+	"strings"
+
+	"github.com/user/nanometrics/server/db"
+	"github.com/user/nanometrics/server/models"
+)
+
+func AgentConfigHandler(database *db.DB, pushConfig func(agentID string, cfg *models.AgentConfig)) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		parts := strings.Split(strings.Trim(r.URL.Path, "/"), "/")
+		if len(parts) < 4 {
+			http.Error(w, "invalid path", 400)
+			return
+		}
+		agentID := parts[2]
+
+		switch r.Method {
+		case http.MethodGet:
+			cfg, err := database.GetAgentConfig(agentID)
+			if err != nil {
+				http.Error(w, err.Error(), 500)
+				return
+			}
+			if cfg == nil {
+				cfg = &models.AgentConfig{}
+			}
+			w.Header().Set("Content-Type", "application/json")
+			json.NewEncoder(w).Encode(cfg)
+
+		case http.MethodPut:
+			var cfg models.AgentConfig
+			if err := json.NewDecoder(r.Body).Decode(&cfg); err != nil {
+				http.Error(w, err.Error(), 400)
+				return
+			}
+			if err := database.UpsertAgentConfig(agentID, &cfg); err != nil {
+				http.Error(w, err.Error(), 500)
+				return
+			}
+			if pushConfig != nil {
+				go pushConfig(agentID, &cfg)
+			}
+			w.WriteHeader(http.StatusNoContent)
+
+		default:
+			http.Error(w, "method not allowed", 405)
+		}
+	}
+}
+
+func ServerConfigHandler(database *db.DB) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case http.MethodGet:
+			cfg, err := database.GetServerConfig()
+			if err != nil {
+				http.Error(w, err.Error(), 500)
+				return
+			}
+			w.Header().Set("Content-Type", "application/json")
+			json.NewEncoder(w).Encode(cfg)
+
+		case http.MethodPut:
+			var cfg models.ServerConfig
+			if err := json.NewDecoder(r.Body).Decode(&cfg); err != nil {
+				http.Error(w, err.Error(), 400)
+				return
+			}
+			if err := database.SetServerConfig(cfg); err != nil {
+				http.Error(w, err.Error(), 500)
+				return
+			}
+			w.WriteHeader(http.StatusNoContent)
+
+		default:
+			http.Error(w, "method not allowed", 405)
+		}
+	}
+}
diff --git a/server/handlers/config_test.go b/server/handlers/config_test.go
new file mode 100644
index 0000000..b9ceb87
--- /dev/null
+++ b/server/handlers/config_test.go
@@ -0,0 +1,72 @@
+package handlers_test
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/user/nanometrics/server/db"
+	"github.com/user/nanometrics/server/handlers"
+	"github.com/user/nanometrics/server/models"
+)
+
+func testDB(t *testing.T) *db.DB {
+	d, _ := db.Open(":memory:")
+	t.Cleanup(func() { d.Close() })
+	return d
+}
+
+func TestServerConfigGetPut(t *testing.T) {
+	d := testDB(t)
+	h := handlers.ServerConfigHandler(d)
+
+	r := httptest.NewRequest(http.MethodGet, "/api/config", nil)
+	w := httptest.NewRecorder()
+	h(w, r)
+	if w.Code != 200 {
+		t.Fatalf("GET status: %d", w.Code)
+	}
+	var got models.ServerConfig
+	json.NewDecoder(w.Body).Decode(&got)
+	if got.TileMinWidth != 220 {
+		t.Errorf("tile_min_width défaut: %d", got.TileMinWidth)
+	}
+
+	cfg := models.DefaultServerConfig()
+	cfg.TileMinWidth = 300
+	body, _ := json.Marshal(cfg)
+	r2 := httptest.NewRequest(http.MethodPut, "/api/config", bytes.NewReader(body))
+	w2 := httptest.NewRecorder()
+	h(w2, r2)
+	if w2.Code != 204 {
+		t.Fatalf("PUT status: %d", w2.Code)
+	}
+
+	r3 := httptest.NewRequest(http.MethodGet, "/api/config", nil)
+	w3 := httptest.NewRecorder()
+	h(w3, r3)
+	var got2 models.ServerConfig
+	json.NewDecoder(w3.Body).Decode(&got2)
+	if got2.TileMinWidth != 300 {
+		t.Errorf("tile_min_width après PUT: %d", got2.TileMinWidth)
+	}
+}
+
+func TestAgentsHandler(t *testing.T) {
+	d := testDB(t)
+	h := handlers.AgentsHandler(d)
+
+	r := httptest.NewRequest(http.MethodGet, "/api/agents", nil)
+	w := httptest.NewRecorder()
+	h(w, r)
+	if w.Code != 200 {
+		t.Fatalf("status: %d", w.Code)
+	}
+	var agents []models.Agent
+	json.NewDecoder(w.Body).Decode(&agents)
+	if agents == nil {
+		// tableau vide attendu, pas d'erreur
+	}
+}
diff --git a/server/handlers/icons.go b/server/handlers/icons.go
new file mode 100644
index 0000000..5709554
--- /dev/null
+++ b/server/handlers/icons.go
@@ -0,0 +1,89 @@
+package handlers
+
+import (
+	"bytes"
+	"image"
+	_ "image/jpeg"
+	"image/png"
+	"net/http"
+	"strings"
+
+	"github.com/disintegration/imaging"
+	"github.com/user/nanometrics/server/db"
+)
+
+const maxIconSize = 128
+
+func IconUploadHandler(database *db.DB) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			http.Error(w, "method not allowed", 405)
+			return
+		}
+		parts := strings.Split(strings.Trim(r.URL.Path, "/"), "/")
+		if len(parts) < 4 {
+			http.Error(w, "invalid path", 400)
+			return
+		}
+		agentID := parts[2]
+
+		r.ParseMultipartForm(2 << 20)
+		file, header, err := r.FormFile("icon")
+		if err != nil {
+			http.Error(w, "fichier manquant", 400)
+			return
+		}
+		defer file.Close()
+
+		mime := header.Header.Get("Content-Type")
+		if mime == "" {
+			mime = "image/png"
+		}
+
+		if strings.Contains(mime, "svg") {
+			var buf bytes.Buffer
+			buf.ReadFrom(file)
+			if err := database.SaveIcon(agentID, buf.Bytes(), "image/svg+xml"); err != nil {
+				http.Error(w, err.Error(), 500)
+				return
+			}
+			w.WriteHeader(http.StatusNoContent)
+			return
+		}
+
+		img, _, err := image.Decode(file)
+		if err != nil {
+			http.Error(w, "image invalide", 400)
+			return
+		}
+		resized := imaging.Fit(img, maxIconSize, maxIconSize, imaging.Lanczos)
+		var buf bytes.Buffer
+		if err := png.Encode(&buf, resized); err != nil {
+			http.Error(w, err.Error(), 500)
+			return
+		}
+		if err := database.SaveIcon(agentID, buf.Bytes(), "image/png"); err != nil {
+			http.Error(w, err.Error(), 500)
+			return
+		}
+		w.WriteHeader(http.StatusNoContent)
+	}
+}
+
+func IconGetHandler(database *db.DB) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		parts := strings.Split(strings.Trim(r.URL.Path, "/"), "/")
+		if len(parts) < 4 {
+			http.Error(w, "invalid path", 400)
+			return
+		}
+		agentID := parts[2]
+		data, mime, err := database.GetIcon(agentID)
+		if err != nil {
+			http.Error(w, "not found", 404)
+			return
+		}
+		w.Header().Set("Content-Type", mime)
+		w.Write(data)
+	}
+}
diff --git a/server/handlers/metrics.go b/server/handlers/metrics.go
new file mode 100644
index 0000000..a530fc7
--- /dev/null
+++ b/server/handlers/metrics.go
@@ -0,0 +1,45 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/user/nanometrics/server/db"
+)
+
+func MetricsHistoryHandler(database *db.DB) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		parts := strings.Split(strings.Trim(r.URL.Path, "/"), "/")
+		if len(parts) < 4 {
+			http.Error(w, "invalid path", 400)
+			return
+		}
+		agentID := parts[2]
+
+		now := time.Now().Unix()
+		from := now - 3600
+		to := now
+
+		if v := r.URL.Query().Get("from"); v != "" {
+			if n, err := strconv.ParseInt(v, 10, 64); err == nil {
+				from = n
+			}
+		}
+		if v := r.URL.Query().Get("to"); v != "" {
+			if n, err := strconv.ParseInt(v, 10, 64); err == nil {
+				to = n
+			}
+		}
+
+		history, err := database.GetMetricsHistory(agentID, from, to)
+		if err != nil {
+			http.Error(w, err.Error(), 500)
+			return
+		}
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(history)
+	}
+}
diff --git a/server/transport/mqtt.go b/server/transport/mqtt.go
new file mode 100644
index 0000000..dadeeec
--- /dev/null
+++ b/server/transport/mqtt.go
@@ -0,0 +1,61 @@
+package transport
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+
+	mqtt "github.com/eclipse/paho.mqtt.golang"
+	"github.com/user/nanometrics/server/models"
+)
+
+type MQTTClient struct {
+	client    mqtt.Client
+	topicBase string
+}
+
+func StartMQTT(broker, topicBase string, handler func(*models.AgentMetrics)) (*MQTTClient, error) {
+	mc := &MQTTClient{topicBase: topicBase}
+
+	opts := mqtt.NewClientOptions().
+		AddBroker(broker).
+		SetClientID("nanometrics-server").
+		SetAutoReconnect(true).
+		SetOnConnectHandler(func(c mqtt.Client) {
+			log.Printf("[mqtt] connecté à %s", broker)
+			topic := fmt.Sprintf("%s/+/metrics", topicBase)
+			if tok := c.Subscribe(topic, 0, nil); tok.Wait() && tok.Error() != nil {
+				log.Printf("[mqtt] subscribe error: %v", tok.Error())
+			}
+		}).
+		SetConnectionLostHandler(func(c mqtt.Client, err error) {
+			log.Printf("[mqtt] connexion perdue: %v", err)
+		}).
+		SetDefaultPublishHandler(func(_ mqtt.Client, msg mqtt.Message) {
+			var m models.AgentMetrics
+			if err := json.Unmarshal(msg.Payload(), &m); err != nil {
+				log.Printf("[mqtt] JSON invalide sur %s: %v", msg.Topic(), err)
+				return
+			}
+			if m.Hostname != "" {
+				handler(&m)
+			}
+		})
+
+	mc.client = mqtt.NewClient(opts)
+	if tok := mc.client.Connect(); tok.Wait() && tok.Error() != nil {
+		return nil, fmt.Errorf("mqtt connect: %w", tok.Error())
+	}
+	return mc, nil
+}
+
+func (mc *MQTTClient) PushConfig(hostname string, cfg *models.AgentConfig) error {
+	topic := fmt.Sprintf("%s/%s/config", mc.topicBase, hostname)
+	data, err := json.Marshal(cfg)
+	if err != nil {
+		return err
+	}
+	tok := mc.client.Publish(topic, 1, false, data)
+	tok.Wait()
+	return tok.Error()
+}