From 891c32e288c24af25e272512cd23b845d6918f4e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E4=BD=A0=E7=9A=84=E7=94=A8=E6=88=B7=E5=90=8D?=
 <你的邮箱>
Date: Mon, 3 Nov 2025 19:26:48 +0800
Subject: [PATCH] feat: initial Netts energy orchestrator

---
 .github/workflows/ci.yaml               |  43 ++++
 .gitignore                              |  21 ++
 Makefile                                |  18 ++
 README.md                               |  92 ++++++++
 cmd/server/main.go                      |  46 ++++
 config.example.yaml                     |  29 +++
 docs/api.md                             |  95 ++++++++
 docs/architecture.md                    |  80 +++++++
 docs/deployment.md                      |  92 ++++++++
 go.mod                                  |  14 ++
 go.sum                                  |  12 +
 internal/config/config.go               | 274 +++++++++++++++++++++++
 internal/config/config_test.go          |  53 +++++
 internal/config/types.go                |  46 ++++
 internal/http/doc.go                    |   2 +
 internal/http/server.go                 | 223 ++++++++++++++++++
 internal/logger/logger.go               |  49 ++++
 internal/netts/client.go                | 285 ++++++++++++++++++++++++
 internal/netts/client_test.go           | 185 +++++++++++++++
 internal/netts/doc.go                   |   2 +
 internal/netts/models.go                |  87 ++++++++
 internal/service/doc.go                 |   2 +
 internal/service/energy_service.go      | 241 ++++++++++++++++++++
 internal/service/energy_service_test.go | 183 +++++++++++++++
 pkg/errors/api_error.go                 |  36 +++
 25 files changed, 2210 insertions(+)
 create mode 100644 .github/workflows/ci.yaml
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 README.md
 create mode 100644 cmd/server/main.go
 create mode 100644 config.example.yaml
 create mode 100644 docs/api.md
 create mode 100644 docs/architecture.md
 create mode 100644 docs/deployment.md
 create mode 100644 go.mod
 create mode 100644 go.sum
 create mode 100644 internal/config/config.go
 create mode 100644 internal/config/config_test.go
 create mode 100644 internal/config/types.go
 create mode 100644 internal/http/doc.go
 create mode 100644 internal/http/server.go
 create mode 100644 internal/logger/logger.go
 create mode 100644 internal/netts/client.go
 create mode 100644 internal/netts/client_test.go
 create mode 100644 internal/netts/doc.go
 create mode 100644 internal/netts/models.go
 create mode 100644 internal/service/doc.go
 create mode 100644 internal/service/energy_service.go
 create mode 100644 internal/service/energy_service_test.go
 create mode 100644 pkg/errors/api_error.go

diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
new file mode 100644
index 0000000..1f3343d
--- /dev/null
+++ b/.github/workflows/ci.yaml
@@ -0,0 +1,43 @@
+name: CI
+
+on:
+  push:
+    branches: [ main, master ]
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: "1.24"
+
+      - name: Go module cache
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/go/pkg/mod
+            ~/.cache/go-build
+          key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+          restore-keys: |
+            ${{ runner.os }}-go-
+
+      - name: Check formatting
+        run: |
+          gofmt -l . | tee /tmp/gofmt.txt
+          if [ -s /tmp/gofmt.txt ]; then
+            echo "The following files need gofmt:"
+            cat /tmp/gofmt.txt
+            exit 1
+          fi
+
+      - name: Go vet
+        run: go vet ./...
+
+      - name: Run tests
+        run: go test ./...
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..eccd399
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,21 @@
+# Binaries
+/bin/
+/dist/
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Build artifacts
+/coverage/
+/tmp/
+
+# Editor files
+.DS_Store
+*.swp
+*.swo
+
+# Configuration overrides
+.env
+config.local.yaml
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..1ba5074
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,18 @@
+SHELL := /bin/bash
+
+.PHONY: fmt vet test run build
+
+fmt:
+	gofmt -w $(shell go list -f '{{.Dir}}' ./...)
+
+vet:
+	go vet ./...
+
+test:
+	go test ./...
+
+build:
+	go build -o bin/netts-energy ./cmd/server
+
+run:
+	go run ./cmd/server -config config.yaml
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..53821d5
--- /dev/null
+++ b/README.md
@@ -0,0 +1,92 @@
+# Netts Energy Orchestrator
+
+Netts Energy Orchestrator 是一个使用 Go 实现的独立服务，用于为自动到账系统中的 TRON 地址自动租赁能量。它集成了 [Netts API v2](https://doc.netts.io/api/v2/)，支持地址自动加入 Host Mode、轮询剩余能量周期并按需购买能量租赁周期，从而显著降低 TRC20 归集的手续费。
+
+## 功能亮点
+
+- ✅ **Netts API 集成**：封装 `usdt/analyze`、`time/add`、`time/status`、`time/order` 等核心接口。
+- 🔁 **自动周期管理**：当剩余周期低于阈值时自动补充，可选自动 Host Mode 注册。
+- 🧩 **独立微服务**：提供 REST API (`POST /api/v1/energy/rent`)，便于与现有到账平台对接。
+- ⚙️ **可配置化**：通过 `config.yaml` 或环境变量管理 API Key、阈值、重试策略等。
+- 📈 **可观察性**：结构化日志、健康检查接口，易于纳入现有监控体系。
+
+## 快速开始
+
+1. 复制配置模板：
+
+   ```bash
+   cp config.example.yaml config.yaml
+   ```
+
+2. 编辑 `config.yaml`，填入 Netts API Key、白名单 IP、Host Mode 回调地址等；或通过环境变量覆盖：
+
+   ```bash
+   export NETTS_API_KEY=your-key
+   export NETTS_REAL_IP=1.2.3.4
+   ```
+
+3. 运行服务：
+
+   ```bash
+   go run ./cmd/server -config config.yaml
+   ```
+
+4. 调用接口租赁能量：
+
+   ```bash
+   curl -X POST http://localhost:8080/api/v1/energy/rent \
+     -H "Content-Type: application/json" \
+     -d '{
+       "from_address": "Txxx", 
+       "to_address": "Tyyy",
+       "amount": "200.0"
+     }'
+   ```
+
+   返回值包含分析结果、是否新增 Host Mode、下单详情以及最新剩余周期。
+
+## 配置说明
+
+参见 `config.example.yaml`，主要段落如下：
+
+- `server`：HTTP 服务监听地址、超时等。
+- `netts`：Netts API 参数（`apiKey` 可通过 `NETTS_API_KEY` 覆盖）。
+- `energy`：
+  - `autoAddHost`：是否自动调用 `time/add` 把地址加入 Host Mode。
+  - `minCycles` / `targetCycles`：低于最小阈值时补足到目标阈值。
+  - `postOrderWait`：下单后等待能量生效的时间。
+- `logging`：日志级别与输出格式（text/json）。
+
+更多环境变量详见 `internal/config/config.go` 中的 `envPrefix` 定义。
+
+## REST API
+
+`POST /api/v1/energy/rent`
+
+```json
+{
+  "from_address": "源地址（监控地址）",
+  "to_address": "归集地址",
+  "amount": "USDT 数量，可选，默认 100",
+  "callback_url": "可选，覆盖 config 默认回调"
+}
+```
+
+响应字段包括推荐能量、下单情况、当前 Host Mode 状态等，详细 schema 请见 `docs/api.md`。
+
+## 测试与质量
+
+```bash
+go test ./...
+golangci-lint run        # 若本地已安装，可执行静态检查
+```
+
+CI 流程（`.github/workflows/ci.yaml`）会执行 `go fmt`, `go vet`, `go test`。
+
+## 与自动到账系统的集成
+
+- 对接点：在归集服务中，当检测到能量不足（或计划归集）时调用本服务接口即可。
+- 配置建议：将主系统的数据库中保存的地址同步到 Netts Host Mode，或在首次归集前调用 `rent` 接口，由服务自动注册/购买能量。
+- 监控：可通过 `/healthz` 结合现有 Prometheus/Consul 健康检查；同时建议订阅 Netts 提供的 webhook 以获知能量下发事件。
+
+更多架构细节、部署流程以及 CI/CD 建议请参阅 `docs/architecture.md` 与 `docs/deployment.md`。
diff --git a/cmd/server/main.go b/cmd/server/main.go
new file mode 100644
index 0000000..bef1a3d
--- /dev/null
+++ b/cmd/server/main.go
@@ -0,0 +1,46 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+
+	appconfig "github.com/D36u99er/bc-netts-energy/internal/config"
+	serverhttp "github.com/D36u99er/bc-netts-energy/internal/http"
+	applogger "github.com/D36u99er/bc-netts-energy/internal/logger"
+	"github.com/D36u99er/bc-netts-energy/internal/netts"
+	"github.com/D36u99er/bc-netts-energy/internal/service"
+)
+
+func main() {
+	configPath := flag.String("config", "", "path to configuration file")
+	flag.Parse()
+
+	cfg, err := appconfig.Load(*configPath)
+	if err != nil {
+		log.Fatalf("failed to load configuration: %v", err)
+	}
+
+	logger := applogger.New(cfg.Logging.Level, cfg.Logging.Format)
+	logger.Info("configuration loaded",
+		"address", cfg.Server.Address,
+		"netts_base_url", cfg.Netts.BaseURL,
+	)
+
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGINT, syscall.SIGTERM)
+	defer stop()
+
+	nettsClient := netts.New(cfg.Netts, logger, nil)
+	energySvc := service.NewEnergyService(cfg.Energy, nettsClient, logger)
+	httpServer := serverhttp.NewServer(cfg.Server, energySvc, logger)
+
+	if err := httpServer.Run(ctx); err != nil {
+		logger.Error("server terminated with error", "error", err)
+		os.Exit(1)
+	}
+
+	logger.Info("shutdown complete")
+}
diff --git a/config.example.yaml b/config.example.yaml
new file mode 100644
index 0000000..0e53116
--- /dev/null
+++ b/config.example.yaml
@@ -0,0 +1,29 @@
+server:
+  address: ":8080"
+  readTimeout: 10s
+  writeTimeout: 10s
+  idleTimeout: 60s
+  shutdownTimeout: 15s
+
+netts:
+  apiKey: "replace-with-netts-api-key"
+  baseUrl: "https://netts.io"
+  realIp: "1.2.3.4"
+  callbackUrl: "https://your-domain.com/netts/callback"
+  httpTimeout: 15s
+  retry:
+    maxAttempts: 3
+    backoff: 2s
+    maxBackoff: 10s
+
+energy:
+  autoAddHost: true
+  minCycles: 3
+  targetCycles: 10
+  minEnergyThreshold: 32000
+  postOrderWait: 3s
+  defaultAnalyzeValue: "100.00"
+
+logging:
+  level: info
+  format: text
diff --git a/docs/api.md b/docs/api.md
new file mode 100644
index 0000000..dbbe15e
--- /dev/null
+++ b/docs/api.md
@@ -0,0 +1,95 @@
+# REST API 文档
+
+## POST `/api/v1/energy/rent`
+
+为指定 TRON 地址分析能量需求、确保 Host Mode 状态，并根据配置自动购买能量周期。
+
+### 请求体
+
+```json
+{
+  "from_address": "T地址",      // 必填，需与 Netts Host Mode 地址一致
+  "to_address": "T地址",        // 必填，归集目标地址
+  "amount": "200.0",           // 可选，USDT 数量，默认 100.00
+  "callback_url": "https://..."// 可选，覆盖配置中的 callback
+}
+```
+
+### 成功响应
+
+```json
+{
+  "from_address": "TFrom...",
+  "to_address": "TTo...",
+  "amount": "200.0",
+  "address_added": true,
+  "recommended_energy": 131000,
+  "energy_needed": 131000,
+  "cycles_before": 2,
+  "cycles_after": 5,
+  "cycles_purchased": 3,
+  "total_cycles": 5,
+  "order_id": "ORD-20231109-XXXX",
+  "order_status": "confirmed",
+  "total_cost": 9.75,
+  "next_delegation_time": 1700000000,
+  "analysis": {
+    "sender_address": "...",
+    "receiver_address": "...",
+    "usdt_amount": "200.0",
+    "recommended_energy": 131000,
+    "energy_needed": 131000,
+    "bandwidth_needed": 345,
+    "cost_breakdown": {
+      "energy_cost": "4.5",
+      "bandwidth_cost": "1.0",
+      "total_cost_trx": "5.5"
+    },
+    "savings_analysis": {
+      "vs_direct_burn": "21.0",
+      "vs_staking": "7.5",
+      "savings_percentage": 80.1
+    }
+  },
+  "status": {
+    "mode": "normal",
+    "status": "active",
+    "cycles_remaining": 5,
+    "open_orders": 0,
+    "expiry_time": 1700100000
+  }
+}
+```
+
+字段说明：
+
+| 字段 | 含义 |
+| ---- | ---- |
+| `address_added` | 是否在本次调用中自动执行了 `time/add` |
+| `cycles_before` / `cycles_after` | 调用前后剩余周期 |
+| `cycles_purchased` | 本次下单购买的周期数（如果无需下单，字段不存在） |
+| `analysis` | 直接透传 Netts `usdt/analyze` 的结果 |
+| `status` | 透传 Netts `time/status` 的核心字段 |
+
+### 错误响应
+
+```json
+{
+  "error": "failed to ensure energy",
+  "details": "address Txxx not in host mode and autoAddHost disabled"
+}
+```
+
+HTTP 状态码：
+
+| 状态码 | 说明 |
+| ------ | ---- |
+| `200` | 成功 |
+| `400` | 请求体格式错误或地址校验失败 |
+| `502` | 与 Netts API 通信失败、或 Netts 返回错误 |
+
+### 使用建议
+
+- 在归集任务执行前调用，确保能量充足。
+- 结果可缓存短时间（例如 60s），避免频繁重复请求。
+- 如需批量处理，可在外层编排多个地址循环调用。
diff --git a/docs/architecture.md b/docs/architecture.md
new file mode 100644
index 0000000..5535551
--- /dev/null
+++ b/docs/architecture.md
@@ -0,0 +1,80 @@
+# 架构设计
+
+## 总体概览
+
+```
+┌───────────────┐        ┌────────────────┐        ┌─────────────────────┐
+│  Client/BC系统 │  --->  │ Netts Energy API│  --->  │ Netts.io (Host Mode) │
+└───────────────┘        └────────────────┘        └─────────────────────┘
+          │                         │
+          │ REST /api/v1/energy/rent│
+          ▼                         ▼
+┌──────────────────────────────────────────────────────────────────────────┐
+│                            Netts Energy Orchestrator                     │
+│ ┌────────────┐  ┌──────────────────┐  ┌──────────────────────────────┐   │
+│ │ HTTP Server│→│ Energy Service    │→│ Netts Client (API v2)         │   │
+│ │ (chi)      │  │ - 业务规则       │  │ - usdt/analyze               │   │
+│ │            │  │ - Host Mode判断  │  │ - time/status/add/order      │   │
+│ └────────────┘  └──────────────────┘  └──────────────────────────────┘   │
+│                     ▲                                   │               │
+│                     └──────────── config/logger ────────┘               │
+└──────────────────────────────────────────────────────────────────────────┘
+```
+
+## 模块分解
+
+### 1. `cmd/server`
+- 应用入口，解析 `-config` 参数。
+- 初始化配置、日志、Netts Client、业务服务与 HTTP Server。
+
+### 2. `internal/config`
+- 负责加载 YAML 配置与环境变量覆盖。
+- 内置默认值、校验逻辑，确保 API Key 与阈值正确。
+
+### 3. `internal/logger`
+- 基于 `log/slog` 的结构化日志工厂。
+- 支持 text / json 输出格式。
+
+### 4. `internal/netts`
+- 轻量封装 Netts API。
+- 具备重试、User-Agent、X-Real-IP 注入、错误码处理等。
+- 在 `GetAddressStatus` 中把 “Address not found” 映射为可识别的 `ErrAddressNotFound`。
+
+### 5. `internal/service`
+- 业务编排核心：
+  1. 调用 `usdt/analyze` 计算推荐能量；
+  2. 检查 Host Mode 状态，必要时自动 `time/add`；
+  3. 当周期低于阈值时，根据配置 `targetCycles` 自动下单；
+  4. 返回分析详情、周期变化、下单记录。
+- 通过接口解耦，便于单元测试和未来 mock。
+
+### 6. `internal/http`
+- 使用 `chi` 构建 REST API。
+- 提供健康检查与 `POST /api/v1/energy/rent` 主入口。
+- 响应中包含分析、Host Mode 状态以及订单结果，方便上游系统直接使用。
+
+## 关键流程
+
+1. **租赁请求**：上游在归集前发送 `from_address` 与 `to_address`，可附带金额。
+2. **能量分析**：调用 Netts `usdt/analyze` 获取推荐能量。
+3. **Host Mode 确认**：
+   - 如果地址未加入，且配置允许自动加入 ⇒ 调用 `time/add`。
+   - 否则直接报错，交由上游处理。
+4. **周期管理**：
+   - 读取 `time/status`。
+   - 若 `cycles_remaining < minCycles` ⇒ 计算补足数量并调用 `time/order`。
+   - 下单后可选等待 `postOrderWait` 秒，再次查询状态。
+5. **响应汇总**：返回推荐能量、是否新增 Host Mode、下单详情、剩余周期、分析数据等。
+
+## 与既有系统的协作
+
+- **触发时机**：在归集执行前（或按周期任务）调用本服务，确保地址有足够能量。
+- **地址生命周期**：推荐在创建新充值地址时即调用 `rent` 接口，让服务负责 Host Mode 注册；现有地址可批量调用 `time/add` 或逐次触发。
+- **成本监控**：可据 `analysis.cost_breakdown` 与 `OrderResult` 中的 `total_cost` 统计能量开销，并和旧的 Feee 系统成本对比。
+- **告警策略**：根据 `cycles_after`、`status.cycles_remaining` 制定阈值告警；Netts 自带 webhook 可配合使用。
+
+## 扩展点
+
+- **多币种支持**：Netts 文档提供更多接口（如 `prices`、`usdt-public`），可按需扩展。
+- **持久化缓存**：目前状态全由 Netts API 提供，如需本地缓存可在 `service` 层引入数据库或 Redis。
+- **批量调度**：可增加定时任务扫描地址列表并调用 `EnsureEnergy`，形成全自动化闭环。
diff --git a/docs/deployment.md b/docs/deployment.md
new file mode 100644
index 0000000..a14ee5b
--- /dev/null
+++ b/docs/deployment.md
@@ -0,0 +1,92 @@
+# 部署与运维指南
+
+## 环境要求
+
+- Go 1.24+
+- Netts API v2 账号，并完成：
+  - 获取 API Key；
+  - 配置 IP 白名单（若使用代理，可在 `config.yaml` 中设置 `netts.realIp`）；
+  - 充值余额，以便购买能量周期。
+
+## 构建
+
+```bash
+go build -o bin/netts-energy ./cmd/server
+```
+
+可选 Dockerfile（伪代码）：
+
+```dockerfile
+FROM golang:1.24-alpine AS builder
+WORKDIR /app
+COPY . .
+RUN go build -o /build/netts-energy ./cmd/server
+
+FROM alpine:3.20
+WORKDIR /srv/app
+COPY --from=builder /build/netts-energy /usr/local/bin/netts-energy
+COPY config.example.yaml ./config.yaml
+CMD ["netts-energy", "-config", "/srv/app/config.yaml"]
+```
+
+## 运行时配置
+
+1. 根据 `config.example.yaml` 编辑正式配置，或注入环境变量（`NETTS_API_KEY` 等）。
+2. 建议通过 systemd / Supervisor 运行，示例：
+
+   ```
+   [Unit]
+   Description=Netts Energy Orchestrator
+   After=network-online.target
+
+   [Service]
+   ExecStart=/srv/netts/netts-energy -config /srv/netts/config.yaml
+   Restart=on-failure
+   Environment=NETTS_API_KEY=***
+
+   [Install]
+   WantedBy=multi-user.target
+   ```
+
+3. 健康检查：
+   - HTTP GET `http://host:port/healthz` 返回 200。
+   - 可接入 Kubernetes / Nginx upstream 的健康探测。
+
+## CI/CD 建议
+
+仓库内置 GitHub Actions workflow (`.github/workflows/ci.yaml`)：
+
+- 安装依赖；
+- `go fmt` + `go vet`；
+- `go test ./...`。
+
+若需要自动部署服务器，可以在 CI 中加入以下步骤：
+
+1. 在 GitHub 仓库配置 Secrets：
+   - `SSH_HOST` / `SSH_USER` / `SSH_KEY`；
+   - `DEPLOY_PATH` 等自定义变量。
+2. 在 workflow 中追加 job，简例：
+
+   ```yaml
+   - name: Deploy
+     if: github.ref == 'refs/heads/main'
+     run: |
+       scp bin/netts-energy ${{ secrets.SSH_USER }}@${{ secrets.SSH_HOST }}:${{ secrets.DEPLOY_PATH }}
+       ssh ${{ secrets.SSH_USER }}@${{ secrets.SSH_HOST }} 'systemctl restart netts-energy'
+   ```
+
+> 注：部署脚本默认留空，需根据实际服务器环境完善。
+
+## 与现有自动到账系统的集成
+
+1. **地址维护**：在充值服务创建新用户地址后，触发一次 `rent` 调用，让服务自动加入 Host Mode。
+2. **归集流程**：在执行 TRC20 归集前调用 `rent` 接口，确保能量充足后再发起链上交易。
+3. **降级策略**：若 Netts API 不可用，可回退到旧的 Feee 方案；建议通过 Prometheus 指标或报警系统监控 `rent` 接口的失败率。
+4. **费用对比**：响应中的 `analysis.cost_breakdown` 与订单 `total_cost` 方便和现有成本核算系统对接。
+
+## 运维建议
+
+- **日志**：标准输出为结构化日志，建议接入 Loki / ELK 做集中采集。
+- **监控**：结合 Netts webhook 与本服务返回数据，设置周期不足、下单失败等告警。
+- **升级**：新增 Netts 接口（例如 `time/infinitystart`）时，可在 `internal/netts` 中扩展方法并追加 service 策略。
+- **安全**：谨慎保管 API Key；生产环境务必使用 HTTPS 代理或反向代理，限制访问来源。
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..49c598e
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,14 @@
+module github.com/D36u99er/bc-netts-energy
+
+go 1.24.3
+
+require (
+	github.com/go-chi/chi/v5 v5.2.3
+	github.com/stretchr/testify v1.11.1
+	gopkg.in/yaml.v3 v3.0.1
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..67f0533
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,12 @@
+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 v5.2.3 h1:WQIt9uxdsAbgIYgid+BpYc+liqQZGMHRaUwp0JUcvdE=
+github.com/go-chi/chi/v5 v5.2.3/go.mod h1:L2yAIGWB3H+phAw1NxKwWM+7eUH/lU8pOMm5hHcoops=
+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/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
+github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/internal/config/config.go b/internal/config/config.go
new file mode 100644
index 0000000..abcc3e5
--- /dev/null
+++ b/internal/config/config.go
@@ -0,0 +1,274 @@
+package config
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"gopkg.in/yaml.v3"
+)
+
+const (
+	defaultConfigFile = "config.yaml"
+	envPrefix         = "NETTS"
+)
+
+// Config represents the full application configuration.
+type Config struct {
+	Server  ServerConfig  `yaml:"server"`
+	Netts   NettsConfig   `yaml:"netts"`
+	Energy  EnergyConfig  `yaml:"energy"`
+	Logging LoggingConfig `yaml:"logging"`
+}
+
+// ServerConfig controls HTTP server behaviour.
+type ServerConfig struct {
+	Address         string   `yaml:"address"`
+	ReadTimeout     Duration `yaml:"readTimeout"`
+	WriteTimeout    Duration `yaml:"writeTimeout"`
+	IdleTimeout     Duration `yaml:"idleTimeout"`
+	ShutdownTimeout Duration `yaml:"shutdownTimeout"`
+}
+
+// NettsConfig contains credentials and settings for the Netts API.
+type NettsConfig struct {
+	APIKey      string   `yaml:"apiKey"`
+	BaseURL     string   `yaml:"baseUrl"`
+	RealIP      string   `yaml:"realIp"`
+	CallbackURL string   `yaml:"callbackUrl"`
+	HTTPTimeout Duration `yaml:"httpTimeout"`
+	Retry       Retry    `yaml:"retry"`
+}
+
+// Retry controls API retry behaviour.
+type Retry struct {
+	MaxAttempts int      `yaml:"maxAttempts"`
+	Backoff     Duration `yaml:"backoff"`
+	MaxBackoff  Duration `yaml:"maxBackoff"`
+}
+
+// EnergyConfig controls orchestration thresholds.
+type EnergyConfig struct {
+	AutoAddHost         bool     `yaml:"autoAddHost"`
+	MinCycles           int      `yaml:"minCycles"`
+	TargetCycles        int      `yaml:"targetCycles"`
+	MinEnergyThreshold  int      `yaml:"minEnergyThreshold"`
+	PostOrderWait       Duration `yaml:"postOrderWait"`
+	DefaultAnalyzeValue string   `yaml:"defaultAnalyzeValue"`
+}
+
+// LoggingConfig controls logger behaviour.
+type LoggingConfig struct {
+	Level  string `yaml:"level"`
+	Format string `yaml:"format"`
+}
+
+// Load reads configuration from the provided path or default locations.
+func Load(path string) (*Config, error) {
+	cfg := defaultConfig()
+
+	configFile, err := resolveConfigPath(path)
+	if err != nil {
+		return nil, err
+	}
+
+	if configFile != "" {
+		raw, err := os.ReadFile(configFile)
+		if err != nil {
+			return nil, fmt.Errorf("read config file %q: %w", configFile, err)
+		}
+		if err := yaml.Unmarshal(raw, &cfg); err != nil {
+			return nil, fmt.Errorf("parse config file %q: %w", configFile, err)
+		}
+	}
+
+	applyDefaults(&cfg)
+	applyEnvOverrides(&cfg)
+
+	if err := cfg.Validate(); err != nil {
+		return nil, err
+	}
+	return &cfg, nil
+}
+
+// DefaultConfig returns a configuration populated with defaults.
+func defaultConfig() Config {
+	return Config{
+		Server: ServerConfig{
+			Address:         ":8080",
+			ReadTimeout:     Duration(10 * time.Second),
+			WriteTimeout:    Duration(10 * time.Second),
+			IdleTimeout:     Duration(60 * time.Second),
+			ShutdownTimeout: Duration(15 * time.Second),
+		},
+		Netts: NettsConfig{
+			BaseURL:     "https://netts.io",
+			HTTPTimeout: Duration(15 * time.Second),
+			Retry: Retry{
+				MaxAttempts: 3,
+				Backoff:     Duration(2 * time.Second),
+				MaxBackoff:  Duration(10 * time.Second),
+			},
+		},
+		Energy: EnergyConfig{
+			AutoAddHost:         true,
+			MinCycles:           3,
+			TargetCycles:        10,
+			MinEnergyThreshold:  32000,
+			PostOrderWait:       Duration(3 * time.Second),
+			DefaultAnalyzeValue: "100.00",
+		},
+		Logging: LoggingConfig{
+			Level:  "info",
+			Format: "text",
+		},
+	}
+}
+
+func applyDefaults(cfg *Config) {
+	if strings.TrimSpace(cfg.Server.Address) == "" {
+		cfg.Server.Address = ":8080"
+	}
+
+	cfg.Server.ReadTimeout.SetDefault(10 * time.Second)
+	cfg.Server.WriteTimeout.SetDefault(10 * time.Second)
+	cfg.Server.IdleTimeout.SetDefault(60 * time.Second)
+	cfg.Server.ShutdownTimeout.SetDefault(15 * time.Second)
+
+	if strings.TrimSpace(cfg.Netts.BaseURL) == "" {
+		cfg.Netts.BaseURL = "https://netts.io"
+	}
+	cfg.Netts.HTTPTimeout.SetDefault(15 * time.Second)
+	if cfg.Netts.Retry.MaxAttempts <= 0 {
+		cfg.Netts.Retry.MaxAttempts = 3
+	}
+	cfg.Netts.Retry.Backoff.SetDefault(2 * time.Second)
+	cfg.Netts.Retry.MaxBackoff.SetDefault(10 * time.Second)
+
+	if cfg.Energy.MinCycles <= 0 {
+		cfg.Energy.MinCycles = 3
+	}
+	if cfg.Energy.TargetCycles <= 0 {
+		cfg.Energy.TargetCycles = 10
+	}
+	if cfg.Energy.TargetCycles < cfg.Energy.MinCycles {
+		cfg.Energy.TargetCycles = cfg.Energy.MinCycles
+	}
+	if cfg.Energy.MinEnergyThreshold <= 0 {
+		cfg.Energy.MinEnergyThreshold = 32000
+	}
+	cfg.Energy.PostOrderWait.SetDefault(3 * time.Second)
+	if cfg.Energy.DefaultAnalyzeValue == "" {
+		cfg.Energy.DefaultAnalyzeValue = "100.00"
+	}
+
+	if cfg.Logging.Level == "" {
+		cfg.Logging.Level = "info"
+	}
+	if cfg.Logging.Format == "" {
+		cfg.Logging.Format = "text"
+	}
+}
+
+func applyEnvOverrides(cfg *Config) {
+	if v := os.Getenv(envVar("API_KEY")); v != "" {
+		cfg.Netts.APIKey = v
+	}
+	if v := os.Getenv(envVar("BASE_URL")); v != "" {
+		cfg.Netts.BaseURL = v
+	}
+	if v := os.Getenv(envVar("REAL_IP")); v != "" {
+		cfg.Netts.RealIP = v
+	}
+	if v := os.Getenv(envVar("CALLBACK_URL")); v != "" {
+		cfg.Netts.CallbackURL = v
+	}
+	if v := os.Getenv(envVar("AUTO_ADD_HOST")); v != "" {
+		cfg.Energy.AutoAddHost = strings.EqualFold(v, "true") || v == "1"
+	}
+	if v := os.Getenv(envVar("MIN_CYCLES")); v != "" {
+		if parsed, err := parseInt(v); err == nil {
+			cfg.Energy.MinCycles = parsed
+		}
+	}
+	if v := os.Getenv(envVar("TARGET_CYCLES")); v != "" {
+		if parsed, err := parseInt(v); err == nil {
+			cfg.Energy.TargetCycles = parsed
+		}
+	}
+	if v := os.Getenv(envVar("MIN_ENERGY_THRESHOLD")); v != "" {
+		if parsed, err := parseInt(v); err == nil {
+			cfg.Energy.MinEnergyThreshold = parsed
+		}
+	}
+	if v := os.Getenv(envVar("LOG_LEVEL")); v != "" {
+		cfg.Logging.Level = v
+	}
+	if v := os.Getenv(envVar("LOG_FORMAT")); v != "" {
+		cfg.Logging.Format = v
+	}
+}
+
+// Validate performs configuration validation.
+func (c *Config) Validate() error {
+	var problems []string
+
+	if strings.TrimSpace(c.Netts.APIKey) == "" {
+		problems = append(problems, "netts.apiKey is required (or NETTS_API_KEY env)")
+	}
+	if !strings.HasPrefix(c.Netts.BaseURL, "http") {
+		problems = append(problems, "netts.baseUrl must be an absolute URL")
+	}
+	if c.Energy.MinCycles <= 0 {
+		problems = append(problems, "energy.minCycles must be > 0")
+	}
+	if c.Energy.TargetCycles < c.Energy.MinCycles {
+		problems = append(problems, "energy.targetCycles must be >= energy.minCycles")
+	}
+	if c.Energy.MinEnergyThreshold <= 0 {
+		problems = append(problems, "energy.minEnergyThreshold must be > 0")
+	}
+
+	if len(problems) > 0 {
+		return errors.New(strings.Join(problems, "; "))
+	}
+	return nil
+}
+
+func resolveConfigPath(path string) (string, error) {
+	if path != "" {
+		if _, err := os.Stat(path); err != nil {
+			return "", fmt.Errorf("config file %q: %w", path, err)
+		}
+		return path, nil
+	}
+
+	searchPaths := []string{
+		defaultConfigFile,
+		filepath.Join("config", defaultConfigFile),
+		filepath.Join("..", defaultConfigFile),
+	}
+
+	for _, candidate := range searchPaths {
+		if _, err := os.Stat(candidate); err == nil {
+			return candidate, nil
+		}
+	}
+	return "", nil
+}
+
+func envVar(key string) string {
+	return fmt.Sprintf("%s_%s", envPrefix, strings.ToUpper(strings.ReplaceAll(key, ".", "_")))
+}
+
+func parseInt(value string) (int, error) {
+	var parsed int
+	_, err := fmt.Sscanf(value, "%d", &parsed)
+	if err != nil {
+		return 0, fmt.Errorf("parse int %q: %w", value, err)
+	}
+	return parsed, nil
+}
diff --git a/internal/config/config_test.go b/internal/config/config_test.go
new file mode 100644
index 0000000..c4b2701
--- /dev/null
+++ b/internal/config/config_test.go
@@ -0,0 +1,53 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestLoadDefaultsWithEnv(t *testing.T) {
+	t.Setenv("NETTS_API_KEY", "env-key")
+
+	cfg, err := Load("")
+	require.NoError(t, err)
+
+	assert.Equal(t, ":8080", cfg.Server.Address)
+	assert.Equal(t, "https://netts.io", cfg.Netts.BaseURL)
+	assert.Equal(t, 3, cfg.Energy.MinCycles)
+	assert.Equal(t, 10, cfg.Energy.TargetCycles)
+	assert.Equal(t, "env-key", cfg.Netts.APIKey)
+}
+
+func TestLoadFromFileOverridesDefaults(t *testing.T) {
+	dir := t.TempDir()
+	file := filepath.Join(dir, "config.yaml")
+
+	body := `
+server:
+  address: ":9090"
+  readTimeout: 5s
+netts:
+  apiKey: "file-key"
+  baseUrl: "https://example.com"
+energy:
+  minCycles: 5
+  targetCycles: 8
+logging:
+  level: debug
+`
+	require.NoError(t, os.WriteFile(file, []byte(body), 0o600))
+
+	cfg, err := Load(file)
+	require.NoError(t, err)
+
+	assert.Equal(t, ":9090", cfg.Server.Address)
+	assert.Equal(t, "https://example.com", cfg.Netts.BaseURL)
+	assert.Equal(t, 5, cfg.Energy.MinCycles)
+	assert.Equal(t, 8, cfg.Energy.TargetCycles)
+	assert.Equal(t, "file-key", cfg.Netts.APIKey)
+	assert.Equal(t, "debug", cfg.Logging.Level)
+}
diff --git a/internal/config/types.go b/internal/config/types.go
new file mode 100644
index 0000000..4bc24a9
--- /dev/null
+++ b/internal/config/types.go
@@ -0,0 +1,46 @@
+package config
+
+import (
+	"fmt"
+	"time"
+
+	"gopkg.in/yaml.v3"
+)
+
+// Duration wraps time.Duration to support YAML unmarshalling from strings.
+type Duration time.Duration
+
+// UnmarshalYAML parses a duration string such as "5s" or "2m".
+func (d *Duration) UnmarshalYAML(value *yaml.Node) error {
+	if value.Kind != yaml.ScalarNode {
+		return fmt.Errorf("duration must be a string, got %s", value.ShortTag())
+	}
+	parsed, err := time.ParseDuration(value.Value)
+	if err != nil {
+		return fmt.Errorf("parse duration %q: %w", value.Value, err)
+	}
+	*d = Duration(parsed)
+	return nil
+}
+
+// MarshalYAML converts the duration to a string value.
+func (d Duration) MarshalYAML() (any, error) {
+	return time.Duration(d).String(), nil
+}
+
+// Duration returns the underlying time.Duration.
+func (d Duration) Duration() time.Duration {
+	return time.Duration(d)
+}
+
+// IsZero reports whether the duration has been set.
+func (d Duration) IsZero() bool {
+	return time.Duration(d) == 0
+}
+
+// SetDefault assigns the provided default if the duration is zero.
+func (d *Duration) SetDefault(def time.Duration) {
+	if d.IsZero() {
+		*d = Duration(def)
+	}
+}
diff --git a/internal/http/doc.go b/internal/http/doc.go
new file mode 100644
index 0000000..dd3bdae
--- /dev/null
+++ b/internal/http/doc.go
@@ -0,0 +1,2 @@
+// Package http provides HTTP handlers for the energy service.
+package http
diff --git a/internal/http/server.go b/internal/http/server.go
new file mode 100644
index 0000000..eab3a0a
--- /dev/null
+++ b/internal/http/server.go
@@ -0,0 +1,223 @@
+package http
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"net/http"
+	"time"
+
+	appconfig "github.com/D36u99er/bc-netts-energy/internal/config"
+	"github.com/D36u99er/bc-netts-energy/internal/netts"
+	"github.com/D36u99er/bc-netts-energy/internal/service"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
+
+	"log/slog"
+)
+
+// Server wraps the HTTP server.
+type Server struct {
+	cfg         appconfig.ServerConfig
+	httpServer  *http.Server
+	energySvc   *service.EnergyService
+	logger      *slog.Logger
+	shutdownDur time.Duration
+}
+
+// NewServer constructs a Server with routes wired.
+func NewServer(cfg appconfig.ServerConfig, energySvc *service.EnergyService, logger *slog.Logger) *Server {
+	router := chi.NewRouter()
+	router.Use(middleware.RequestID)
+	router.Use(middleware.RealIP)
+	router.Use(middleware.Recoverer)
+
+	s := &Server{
+		cfg:         cfg,
+		energySvc:   energySvc,
+		logger:      logger,
+		shutdownDur: cfg.ShutdownTimeout.Duration(),
+	}
+
+	router.Use(s.loggingMiddleware)
+
+	router.Get("/healthz", s.handleHealth)
+	router.Post("/api/v1/energy/rent", s.handleRentEnergy)
+
+	httpServer := &http.Server{
+		Addr:         cfg.Address,
+		Handler:      router,
+		ReadTimeout:  cfg.ReadTimeout.Duration(),
+		WriteTimeout: cfg.WriteTimeout.Duration(),
+		IdleTimeout:  cfg.IdleTimeout.Duration(),
+	}
+	s.httpServer = httpServer
+	return s
+}
+
+// Run starts the HTTP server and listens for shutdown from context.
+func (s *Server) Run(ctx context.Context) error {
+	errCh := make(chan error, 1)
+
+	go func() {
+		s.logger.Info("http server listening", "address", s.cfg.Address)
+		if err := s.httpServer.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
+			errCh <- err
+		}
+	}()
+
+	select {
+	case <-ctx.Done():
+		return s.shutdown(context.Background())
+	case err := <-errCh:
+		return err
+	}
+}
+
+func (s *Server) shutdown(ctx context.Context) error {
+	timeout := s.shutdownDur
+	if timeout <= 0 {
+		timeout = 15 * time.Second
+	}
+	ctx, cancel := context.WithTimeout(ctx, timeout)
+	defer cancel()
+
+	s.logger.Info("shutting down http server", "timeout", timeout)
+	return s.httpServer.Shutdown(ctx)
+}
+
+func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
+	writeJSON(w, http.StatusOK, map[string]string{
+		"status": "ok",
+		"time":   time.Now().UTC().Format(time.RFC3339Nano),
+	})
+}
+
+func (s *Server) handleRentEnergy(w http.ResponseWriter, r *http.Request) {
+	var req rentEnergyRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid request payload", err)
+		return
+	}
+	defer r.Body.Close()
+
+	ctx := r.Context()
+	resp, err := s.energySvc.EnsureEnergy(ctx, service.EnsureEnergyRequest{
+		FromAddress: req.FromAddress,
+		ToAddress:   req.ToAddress,
+		Amount:      req.Amount,
+		CallbackURL: req.CallbackURL,
+	})
+	if err != nil {
+		s.logger.ErrorContext(ctx, "ensure energy failed", "error", err)
+		writeError(w, http.StatusBadGateway, "failed to ensure energy", err)
+		return
+	}
+
+	writeJSON(w, http.StatusOK, newRentEnergyResponse(resp))
+}
+
+func (s *Server) loggingMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		start := time.Now()
+		ww := middleware.NewWrapResponseWriter(w, r.ProtoMajor)
+		next.ServeHTTP(ww, r)
+
+		s.logger.Info("http request",
+			"method", r.Method,
+			"path", r.URL.Path,
+			"status", ww.Status(),
+			"duration", time.Since(start),
+			"request_id", middleware.GetReqID(r.Context()),
+		)
+	})
+}
+
+type rentEnergyRequest struct {
+	FromAddress string `json:"from_address"`
+	ToAddress   string `json:"to_address"`
+	Amount      string `json:"amount"`
+	CallbackURL string `json:"callback_url"`
+}
+
+type rentEnergyResponse struct {
+	FromAddress       string                `json:"from_address"`
+	ToAddress         string                `json:"to_address"`
+	Amount            string                `json:"amount"`
+	AddressAdded      bool                  `json:"address_added"`
+	RecommendedEnergy int                   `json:"recommended_energy"`
+	EnergyNeeded      int                   `json:"energy_needed"`
+	CyclesBefore      int                   `json:"cycles_before"`
+	CyclesAfter       int                   `json:"cycles_after"`
+	CyclesPurchased   int                   `json:"cycles_purchased,omitempty"`
+	TotalCycles       int                   `json:"total_cycles,omitempty"`
+	OrderID           string                `json:"order_id,omitempty"`
+	OrderStatus       string                `json:"order_status,omitempty"`
+	TotalCost         float64               `json:"total_cost,omitempty"`
+	NextDelegation    int64                 `json:"next_delegation_time,omitempty"`
+	Analysis          netts.TransferDetails `json:"analysis"`
+	Status            *statusSummary        `json:"status,omitempty"`
+}
+
+type statusSummary struct {
+	Mode            string `json:"mode"`
+	Status          string `json:"status"`
+	CyclesRemaining int    `json:"cycles_remaining"`
+	OpenOrders      int    `json:"open_orders"`
+	ExpiryTime      int64  `json:"expiry_time"`
+}
+
+func newRentEnergyResponse(resp *service.EnsureEnergyResponse) rentEnergyResponse {
+	var status *statusSummary
+	if resp.Status != nil {
+		status = &statusSummary{
+			Mode:            resp.Status.Mode,
+			Status:          resp.Status.Status,
+			CyclesRemaining: resp.Status.CyclesRemaining,
+			OpenOrders:      resp.Status.OpenOrders,
+			ExpiryTime:      resp.Status.ExpiryTime,
+		}
+	}
+	return rentEnergyResponse{
+		FromAddress:       resp.FromAddress,
+		ToAddress:         resp.ToAddress,
+		Amount:            resp.Amount,
+		AddressAdded:      resp.AddressAdded,
+		RecommendedEnergy: resp.RecommendedEnergy,
+		EnergyNeeded:      resp.EnergyNeeded,
+		CyclesBefore:      resp.CyclesBefore,
+		CyclesAfter:       resp.CyclesAfter,
+		CyclesPurchased:   resp.CyclesPurchased,
+		TotalCycles:       resp.TotalCycles,
+		OrderID:           resp.OrderID,
+		OrderStatus:       resp.OrderStatus,
+		TotalCost:         resp.TotalCost,
+		NextDelegation:    resp.NextDelegation,
+		Analysis:          resp.Analysis,
+		Status:            status,
+	}
+}
+
+func writeJSON(w http.ResponseWriter, status int, body any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(body)
+}
+
+func writeError(w http.ResponseWriter, status int, message string, err error) {
+	type errorBody struct {
+		Error   string `json:"error"`
+		Details string `json:"details,omitempty"`
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	detail := ""
+	if err != nil {
+		detail = err.Error()
+	}
+	_ = json.NewEncoder(w).Encode(errorBody{
+		Error:   message,
+		Details: detail,
+	})
+}
diff --git a/internal/logger/logger.go b/internal/logger/logger.go
new file mode 100644
index 0000000..c9812eb
--- /dev/null
+++ b/internal/logger/logger.go
@@ -0,0 +1,49 @@
+package logger
+
+import (
+	"log/slog"
+	"os"
+	"strings"
+	"time"
+)
+
+// New builds a slog.Logger based on level and format configuration.
+func New(level, format string) *slog.Logger {
+	slogLevel := parseLevel(level)
+
+	var handler slog.Handler
+	opts := &slog.HandlerOptions{
+		Level:     slogLevel,
+		AddSource: true,
+		ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
+			if a.Key == slog.TimeKey {
+				a.Value = slog.StringValue(time.Now().UTC().Format(time.RFC3339Nano))
+			}
+			return a
+		},
+	}
+
+	switch strings.ToLower(format) {
+	case "json":
+		handler = slog.NewJSONHandler(os.Stdout, opts)
+	default:
+		handler = slog.NewTextHandler(os.Stdout, opts)
+	}
+
+	return slog.New(handler)
+}
+
+func parseLevel(level string) slog.Level {
+	switch strings.ToLower(level) {
+	case "debug":
+		return slog.LevelDebug
+	case "warn", "warning":
+		return slog.LevelWarn
+	case "error":
+		return slog.LevelError
+	case "info", "":
+		return slog.LevelInfo
+	default:
+		return slog.LevelInfo
+	}
+}
diff --git a/internal/netts/client.go b/internal/netts/client.go
new file mode 100644
index 0000000..8c9c1ad
--- /dev/null
+++ b/internal/netts/client.go
@@ -0,0 +1,285 @@
+package netts
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	appconfig "github.com/D36u99er/bc-netts-energy/internal/config"
+	appErrors "github.com/D36u99er/bc-netts-energy/pkg/errors"
+
+	"log/slog"
+)
+
+var (
+	// ErrAddressNotFound is returned when an address is not registered in Host Mode.
+	ErrAddressNotFound = errors.New("netts: address not found in host mode")
+)
+
+// Client interacts with the Netts API.
+type Client struct {
+	baseURL     string
+	apiKey      string
+	realIP      string
+	callbackURL string
+	userAgent   string
+
+	httpClient *http.Client
+	logger     *slog.Logger
+	retry      RetryConfig
+}
+
+// RetryConfig describes retry behaviour.
+type RetryConfig struct {
+	MaxAttempts int
+	Backoff     time.Duration
+	MaxBackoff  time.Duration
+}
+
+// New creates a Netts client with provided configuration.
+func New(cfg appconfig.NettsConfig, logger *slog.Logger, httpClient *http.Client) *Client {
+	if httpClient == nil {
+		httpClient = &http.Client{
+			Timeout: cfg.HTTPTimeout.Duration(),
+		}
+	}
+
+	return &Client{
+		baseURL:     strings.TrimRight(cfg.BaseURL, "/"),
+		apiKey:      cfg.APIKey,
+		realIP:      cfg.RealIP,
+		callbackURL: cfg.CallbackURL,
+		userAgent:   "bc-netts-energy/1.0 (+https://github.com/D36u99er/bc-netts-energy)",
+		httpClient:  httpClient,
+		logger:      logger,
+		retry: RetryConfig{
+			MaxAttempts: max(cfg.Retry.MaxAttempts, 1),
+			Backoff:     cfg.Retry.Backoff.Duration(),
+			MaxBackoff:  cfg.Retry.MaxBackoff.Duration(),
+		},
+	}
+}
+
+// WithHTTPClient returns a shallow copy of the client using the provided HTTP client.
+func (c *Client) WithHTTPClient(httpClient *http.Client) *Client {
+	if httpClient == nil {
+		return c
+	}
+	clone := *c
+	clone.httpClient = httpClient
+	return &clone
+}
+
+// AnalyzeUSDT analyses a USDT transfer and returns recommended energy usage.
+func (c *Client) AnalyzeUSDT(ctx context.Context, req AnalyzeUSDTRequest) (*AnalyzeUSDTData, error) {
+	var resp APIResponse[AnalyzeUSDTData]
+	err := c.do(ctx, http.MethodPost, "/apiv2/usdt/analyze", req, func(r *http.Request) {
+		r.Header.Set("Content-Type", "application/json")
+		r.Header.Set("X-API-KEY", c.apiKey)
+		if c.realIP != "" {
+			r.Header.Set("X-Real-IP", c.realIP)
+		}
+	}, &resp)
+	if err != nil {
+		return nil, err
+	}
+	if resp.Code != 0 {
+		return nil, c.apiError(resp.Code, resp.Msg, 0)
+	}
+
+	return &resp.Data, nil
+}
+
+// GetAddressStatus retrieves Host Mode status for an address.
+func (c *Client) GetAddressStatus(ctx context.Context, address string) (*AddressStatus, error) {
+	var resp APIResponse[AddressStatus]
+	path := fmt.Sprintf("/apiv2/time/status/%s", url.PathEscape(address))
+	err := c.do(ctx, http.MethodGet, path, nil, func(r *http.Request) {
+		r.Header.Set("X-API-KEY", c.apiKey)
+		if c.realIP != "" {
+			r.Header.Set("X-Real-IP", c.realIP)
+		}
+	}, &resp)
+	if err != nil {
+		var apiErr *appErrors.APIError
+		if errors.As(err, &apiErr) && apiErr.Code == -1 && strings.Contains(strings.ToLower(apiErr.Message), "not found") {
+			return nil, ErrAddressNotFound
+		}
+		return nil, err
+	}
+	if resp.Code != 0 {
+		if strings.Contains(strings.ToLower(resp.Msg), "not found") {
+			return nil, ErrAddressNotFound
+		}
+		return nil, c.apiError(resp.Code, resp.Msg, 0)
+	}
+	return &resp.Data, nil
+}
+
+// AddHostAddress registers an address in Host Mode.
+func (c *Client) AddHostAddress(ctx context.Context, address, callback string) (*AddAddressResult, error) {
+	payload := map[string]any{
+		"api_key": c.apiKey,
+		"address": address,
+	}
+	if callback != "" {
+		payload["callback_url"] = callback
+	} else if c.callbackURL != "" {
+		payload["callback_url"] = c.callbackURL
+	}
+
+	var resp APIResponse[AddAddressResult]
+	err := c.do(ctx, http.MethodPost, "/apiv2/time/add", payload, func(r *http.Request) {
+		r.Header.Set("Content-Type", "application/json")
+		if c.realIP != "" {
+			r.Header.Set("X-Real-IP", c.realIP)
+		}
+	}, &resp)
+	if err != nil {
+		return nil, err
+	}
+	if resp.Code != 0 {
+		return nil, c.apiError(resp.Code, resp.Msg, 0)
+	}
+	return &resp.Data, nil
+}
+
+// OrderCycles purchases a number of energy cycles for an address.
+func (c *Client) OrderCycles(ctx context.Context, address string, cycles int) (*OrderResult, error) {
+	payload := map[string]any{
+		"api_key": c.apiKey,
+		"address": address,
+		"cycles":  cycles,
+	}
+
+	var resp APIResponse[OrderResult]
+	err := c.do(ctx, http.MethodPost, "/apiv2/time/order", payload, func(r *http.Request) {
+		r.Header.Set("Content-Type", "application/json")
+		if c.realIP != "" {
+			r.Header.Set("X-Real-IP", c.realIP)
+		}
+	}, &resp)
+	if err != nil {
+		return nil, err
+	}
+	if resp.Code != 0 {
+		return nil, c.apiError(resp.Code, resp.Msg, 0)
+	}
+	return &resp.Data, nil
+}
+
+func (c *Client) do(ctx context.Context, method, path string, body any, headerFn func(*http.Request), out any) error {
+	fullURL := c.baseURL + path
+	var payload []byte
+	var err error
+	if body != nil {
+		payload, err = json.Marshal(body)
+		if err != nil {
+			return fmt.Errorf("marshal request body: %w", err)
+		}
+	}
+
+	attempt := 0
+	delay := c.retry.Backoff
+	if delay <= 0 {
+		delay = 2 * time.Second
+	}
+	maxBackoff := c.retry.MaxBackoff
+	if maxBackoff <= 0 {
+		maxBackoff = 15 * time.Second
+	}
+
+	for {
+		attempt++
+		req, err := http.NewRequestWithContext(ctx, method, fullURL, bytes.NewReader(payload))
+		if err != nil {
+			return fmt.Errorf("create request: %w", err)
+		}
+		req.Header.Set("User-Agent", c.userAgent)
+
+		if headerFn != nil {
+			headerFn(req)
+		}
+
+		c.logger.Debug("netts request", "method", method, "url", fullURL, "attempt", attempt)
+
+		resp, err := c.httpClient.Do(req)
+		if err != nil {
+			if attempt < c.retry.MaxAttempts {
+				c.logger.Warn("netts request error, retrying", "error", err, "attempt", attempt)
+				select {
+				case <-time.After(delay):
+				case <-ctx.Done():
+					return ctx.Err()
+				}
+				delay = nextBackoff(delay, maxBackoff)
+				continue
+			}
+			return fmt.Errorf("execute request: %w", err)
+		}
+
+		bodyBytes, err := io.ReadAll(resp.Body)
+		resp.Body.Close()
+		if err != nil {
+			return fmt.Errorf("read response: %w", err)
+		}
+
+		c.logger.Debug("netts response", "status", resp.StatusCode, "attempt", attempt)
+
+		if resp.StatusCode >= 500 && attempt < c.retry.MaxAttempts {
+			c.logger.Warn("netts server error, retrying", "status", resp.StatusCode, "attempt", attempt)
+			select {
+			case <-time.After(delay):
+			case <-ctx.Done():
+				return ctx.Err()
+			}
+			delay = nextBackoff(delay, maxBackoff)
+			continue
+		}
+
+		if resp.StatusCode >= 300 {
+			return &appErrors.APIError{
+				HTTPStatus: resp.StatusCode,
+				Message:    strings.TrimSpace(string(bodyBytes)),
+			}
+		}
+
+		if out == nil {
+			return nil
+		}
+		if err := json.Unmarshal(bodyBytes, out); err != nil {
+			return fmt.Errorf("parse response: %w", err)
+		}
+		return nil
+	}
+}
+
+func (c *Client) apiError(code int, message string, status int) error {
+	return &appErrors.APIError{
+		Code:       code,
+		Message:    message,
+		HTTPStatus: status,
+	}
+}
+
+func nextBackoff(current, max time.Duration) time.Duration {
+	next := current * 2
+	if next > max {
+		return max
+	}
+	return next
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
diff --git a/internal/netts/client_test.go b/internal/netts/client_test.go
new file mode 100644
index 0000000..3a3bfb5
--- /dev/null
+++ b/internal/netts/client_test.go
@@ -0,0 +1,185 @@
+package netts
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	appconfig "github.com/D36u99er/bc-netts-energy/internal/config"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"log/slog"
+)
+
+func TestClientAnalyzeUSDT(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/apiv2/usdt/analyze":
+			assert.Equal(t, http.MethodPost, r.Method)
+			assert.Equal(t, "test-key", r.Header.Get("X-API-KEY"))
+			_, err := io.ReadAll(r.Body)
+			require.NoError(t, err)
+			w.Header().Set("Content-Type", "application/json")
+			_, _ = w.Write([]byte(`{
+				"code": 0,
+				"msg": "ok",
+				"data": {
+					"transfer_details": {
+						"sender_address": "TFrom",
+						"receiver_address": "TTo",
+						"usdt_amount": "10.00",
+						"recommended_energy": 131000,
+						"energy_needed": 131000,
+						"bandwidth_needed": 350,
+						"cost_breakdown": {
+							"energy_cost": "3.5",
+							"bandwidth_cost": "1.0",
+							"total_cost_trx": "4.5"
+						},
+						"savings_analysis": {
+							"vs_direct_burn": "20.0",
+							"vs_staking": "5.0",
+							"savings_percentage": 80.5
+						}
+					}
+				}
+			}`))
+		default:
+			w.WriteHeader(http.StatusNotFound)
+		}
+	}))
+	defer server.Close()
+
+	client := newTestClient(server, t)
+
+	resp, err := client.AnalyzeUSDT(context.Background(), AnalyzeUSDTRequest{
+		Sender:   "TFrom",
+		Receiver: "TTo",
+		Amount:   "10.00",
+	})
+	require.NoError(t, err)
+	assert.Equal(t, 131000, resp.TransferDetails.RecommendedEnergy)
+	assert.Equal(t, 131000, resp.TransferDetails.EnergyNeeded)
+	assert.InDelta(t, 80.5, resp.TransferDetails.SavingsAnalysis.SavingsPercentage, 0.01)
+}
+
+func TestClientGetAddressStatus(t *testing.T) {
+	calls := 0
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/apiv2/time/status/TExists":
+			if calls == 0 {
+				w.Header().Set("Content-Type", "application/json")
+				_, _ = w.Write([]byte(`{
+					"code": 0,
+					"msg": "ok",
+					"data": {
+						"address": "TExists",
+						"mode": "normal",
+						"status": "active",
+						"cycles_remaining": 2,
+						"open_orders": 0,
+						"expiry_time": 1700000000
+					}
+				}`))
+			}
+			calls++
+		case "/apiv2/time/status/TMissing":
+			w.Header().Set("Content-Type", "application/json")
+			_, _ = w.Write([]byte(`{
+				"code": -1,
+				"msg": "Address not found in Host Mode",
+				"data": null
+			}`))
+		default:
+			t.Fatalf("unexpected path %s", r.URL.Path)
+		}
+	}))
+	defer server.Close()
+
+	client := newTestClient(server, t)
+
+	status, err := client.GetAddressStatus(context.Background(), "TExists")
+	require.NoError(t, err)
+	assert.Equal(t, 2, status.CyclesRemaining)
+
+	_, err = client.GetAddressStatus(context.Background(), "TMissing")
+	require.Error(t, err)
+	assert.ErrorIs(t, err, ErrAddressNotFound)
+}
+
+func TestClientMutations(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/apiv2/time/add":
+			w.Header().Set("Content-Type", "application/json")
+			_, _ = w.Write([]byte(`{
+				"code": 0,
+				"msg": "Address added",
+				"data": {
+					"address": "TAdded",
+					"callback_url": "https://callback",
+					"timestamp": "2024-01-01T00:00:00Z"
+				}
+			}`))
+		case "/apiv2/time/order":
+			w.Header().Set("Content-Type", "application/json")
+			_, _ = w.Write([]byte(`{
+				"code": 0,
+				"msg": "ok",
+				"data": {
+					"address": "TAdded",
+					"cycles_purchased": 5,
+					"total_cycles": 8,
+					"previous_cycles": 3,
+					"total_cost": 10.5,
+					"price_per_cycle": 2.1,
+					"order_id": "ORD-1",
+					"transaction_hash": "hash",
+					"payment_method": "account_balance",
+					"balance_after": 100.5,
+					"next_delegation_time": 1700000000,
+					"expiry_time": 1700100000,
+					"status": "confirmed"
+				}
+			}`))
+		default:
+			w.WriteHeader(http.StatusNotFound)
+		}
+	}))
+	defer server.Close()
+
+	client := newTestClient(server, t)
+
+	addResp, err := client.AddHostAddress(context.Background(), "TAdded", "https://callback")
+	require.NoError(t, err)
+	assert.Equal(t, "TAdded", addResp.Address)
+
+	orderResp, err := client.OrderCycles(context.Background(), "TAdded", 5)
+	require.NoError(t, err)
+	assert.Equal(t, 5, orderResp.CyclesPurchased)
+	assert.Equal(t, "ORD-1", orderResp.OrderID)
+}
+
+func newTestClient(server *httptest.Server, t *testing.T) *Client {
+	t.Helper()
+
+	cfg := appconfig.NettsConfig{
+		APIKey:      "test-key",
+		BaseURL:     server.URL,
+		HTTPTimeout: appconfig.Duration(5 * time.Second),
+		Retry: appconfig.Retry{
+			MaxAttempts: 1,
+		},
+	}
+
+	logger := slog.New(slog.NewTextHandler(io.Discard, &slog.HandlerOptions{Level: slog.LevelDebug}))
+	httpClient := server.Client()
+
+	return New(cfg, logger, httpClient)
+}
diff --git a/internal/netts/doc.go b/internal/netts/doc.go
new file mode 100644
index 0000000..b496c9b
--- /dev/null
+++ b/internal/netts/doc.go
@@ -0,0 +1,2 @@
+// Package netts contains the Netts API client.
+package netts
diff --git a/internal/netts/models.go b/internal/netts/models.go
new file mode 100644
index 0000000..f19682d
--- /dev/null
+++ b/internal/netts/models.go
@@ -0,0 +1,87 @@
+package netts
+
+// APIResponse represents Netts standard API response envelope.
+type APIResponse[T any] struct {
+	Code int    `json:"code"`
+	Msg  string `json:"msg"`
+	Data T      `json:"data"`
+}
+
+// AnalyzeUSDTRequest describes the payload for /apiv2/usdt/analyze.
+type AnalyzeUSDTRequest struct {
+	Sender   string `json:"sender"`
+	Receiver string `json:"receiver"`
+	Amount   string `json:"amount"`
+}
+
+// AnalyzeUSDTData contains analysis details for USDT transfer.
+type AnalyzeUSDTData struct {
+	TransferDetails TransferDetails `json:"transfer_details"`
+}
+
+// TransferDetails describes recommended resources for a transfer.
+type TransferDetails struct {
+	SenderAddress      string          `json:"sender_address"`
+	ReceiverAddress    string          `json:"receiver_address"`
+	USDTAmount         string          `json:"usdt_amount"`
+	RecommendedEnergy  int             `json:"recommended_energy"`
+	EnergyNeeded       int             `json:"energy_needed"`
+	BandwidthNeeded    int             `json:"bandwidth_needed"`
+	CostBreakdown      CostBreakdown   `json:"cost_breakdown"`
+	SavingsAnalysis    SavingsAnalysis `json:"savings_analysis"`
+	HasSufficientUSDT  *bool           `json:"has_usdt,omitempty"`
+	RecommendedReserve int             `json:"recommended_energy_reserve,omitempty"`
+}
+
+// CostBreakdown details TRX costs.
+type CostBreakdown struct {
+	EnergyCost    string `json:"energy_cost"`
+	BandwidthCost string `json:"bandwidth_cost"`
+	TotalCostTRX  string `json:"total_cost_trx"`
+}
+
+// SavingsAnalysis summarises cost savings.
+type SavingsAnalysis struct {
+	VsDirectBurn      string  `json:"vs_direct_burn"`
+	VsStaking         string  `json:"vs_staking"`
+	SavingsPercentage float64 `json:"savings_percentage"`
+}
+
+// AddressStatus represents Host Mode status for an address.
+type AddressStatus struct {
+	Address            string  `json:"address"`
+	Mode               string  `json:"mode"`
+	Status             string  `json:"status"`
+	CyclesOrdered      int     `json:"cycles_ordered"`
+	CycleSet           int     `json:"cycle_set"`
+	CyclesCompleted    int     `json:"cycles_completed"`
+	CyclesRemaining    int     `json:"cycles_remaining"`
+	OpenOrders         int     `json:"open_orders"`
+	NextDelegationTime int64   `json:"next_delegation_time"`
+	ExpiryTime         int64   `json:"expiry_time"`
+	BalanceAfter       float64 `json:"balance_after"`
+}
+
+// AddAddressResult captures response from /time/add.
+type AddAddressResult struct {
+	Address     string `json:"address"`
+	CallbackURL string `json:"callback_url,omitempty"`
+	Timestamp   string `json:"timestamp"`
+}
+
+// OrderResult captures order summary from /time/order.
+type OrderResult struct {
+	Address         string  `json:"address"`
+	CyclesPurchased int     `json:"cycles_purchased"`
+	TotalCycles     int     `json:"total_cycles"`
+	PreviousCycles  int     `json:"previous_cycles"`
+	TotalCost       float64 `json:"total_cost"`
+	PricePerCycle   float64 `json:"price_per_cycle"`
+	OrderID         string  `json:"order_id"`
+	TransactionHash string  `json:"transaction_hash"`
+	PaymentMethod   string  `json:"payment_method"`
+	BalanceAfter    float64 `json:"balance_after"`
+	NextDelegation  int64   `json:"next_delegation_time"`
+	ExpiryTime      int64   `json:"expiry_time"`
+	Status          string  `json:"status"`
+}
diff --git a/internal/service/doc.go b/internal/service/doc.go
new file mode 100644
index 0000000..fbdf334
--- /dev/null
+++ b/internal/service/doc.go
@@ -0,0 +1,2 @@
+// Package service contains business logic for energy orchestration.
+package service
diff --git a/internal/service/energy_service.go b/internal/service/energy_service.go
new file mode 100644
index 0000000..8064b91
--- /dev/null
+++ b/internal/service/energy_service.go
@@ -0,0 +1,241 @@
+package service
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"regexp"
+	"time"
+
+	appconfig "github.com/D36u99er/bc-netts-energy/internal/config"
+	"github.com/D36u99er/bc-netts-energy/internal/netts"
+
+	"log/slog"
+)
+
+var tronAddressPattern = regexp.MustCompile(`^T[1-9A-HJ-NP-Za-km-z]{33}$`)
+
+// EnsureEnergyRequest describes a request to guarantee sufficient energy.
+type EnsureEnergyRequest struct {
+	FromAddress string
+	ToAddress   string
+	Amount      string
+	CallbackURL string
+}
+
+// EnsureEnergyResponse summarises the orchestration result.
+type EnsureEnergyResponse struct {
+	FromAddress       string                `json:"from_address"`
+	ToAddress         string                `json:"to_address"`
+	Amount            string                `json:"amount"`
+	AddressAdded      bool                  `json:"address_added"`
+	RecommendedEnergy int                   `json:"recommended_energy"`
+	EnergyNeeded      int                   `json:"energy_needed"`
+	CyclesBefore      int                   `json:"cycles_before"`
+	CyclesAfter       int                   `json:"cycles_after"`
+	CyclesPurchased   int                   `json:"cycles_purchased,omitempty"`
+	TotalCycles       int                   `json:"total_cycles,omitempty"`
+	OrderID           string                `json:"order_id,omitempty"`
+	OrderStatus       string                `json:"order_status,omitempty"`
+	TotalCost         float64               `json:"total_cost,omitempty"`
+	NextDelegation    int64                 `json:"next_delegation_time,omitempty"`
+	Analysis          netts.TransferDetails `json:"analysis"`
+	OrderRaw          *netts.OrderResult    `json:"-"`
+	Status            *netts.AddressStatus  `json:"-"`
+}
+
+// EnergyService coordinates Netts energy rentals.
+type NettsClient interface {
+	AnalyzeUSDT(ctx context.Context, req netts.AnalyzeUSDTRequest) (*netts.AnalyzeUSDTData, error)
+	GetAddressStatus(ctx context.Context, address string) (*netts.AddressStatus, error)
+	AddHostAddress(ctx context.Context, address, callback string) (*netts.AddAddressResult, error)
+	OrderCycles(ctx context.Context, address string, cycles int) (*netts.OrderResult, error)
+}
+
+type EnergyService struct {
+	cfg         appconfig.EnergyConfig
+	nettsClient NettsClient
+	logger      *slog.Logger
+}
+
+// NewEnergyService instantiates an EnergyService.
+func NewEnergyService(cfg appconfig.EnergyConfig, client NettsClient, logger *slog.Logger) *EnergyService {
+	return &EnergyService{
+		cfg:         cfg,
+		nettsClient: client,
+		logger:      logger,
+	}
+}
+
+// EnsureEnergy ensures an address has sufficient energy and cycles.
+func (s *EnergyService) EnsureEnergy(ctx context.Context, req EnsureEnergyRequest) (*EnsureEnergyResponse, error) {
+	if err := s.validateRequest(req); err != nil {
+		return nil, err
+	}
+
+	amount := req.Amount
+	if amount == "" {
+		amount = s.cfg.DefaultAnalyzeValue
+	}
+
+	analysis, err := s.nettsClient.AnalyzeUSDT(ctx, netts.AnalyzeUSDTRequest{
+		Sender:   req.FromAddress,
+		Receiver: req.ToAddress,
+		Amount:   amount,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("analyze transfer: %w", err)
+	}
+
+	transfer := analysis.TransferDetails
+	energyNeeded := transfer.EnergyNeeded
+	if energyNeeded == 0 {
+		energyNeeded = transfer.RecommendedEnergy
+	}
+
+	s.logger.InfoContext(ctx, "analysis completed",
+		"from", req.FromAddress,
+		"to", req.ToAddress,
+		"recommended_energy", transfer.RecommendedEnergy,
+		"energy_needed", energyNeeded,
+	)
+
+	status, addressAdded, err := s.ensureHostMode(ctx, req.FromAddress, req.CallbackURL)
+	if err != nil {
+		return nil, err
+	}
+
+	var (
+		cyclesBefore = 0
+		cyclesAfter  = 0
+		order        *netts.OrderResult
+	)
+
+	if status != nil {
+		cyclesBefore = status.CyclesRemaining
+		if shouldOrderCycles(status, s.cfg.MinCycles) {
+			targetCycles := s.cfg.TargetCycles
+			if targetCycles < s.cfg.MinCycles {
+				targetCycles = s.cfg.MinCycles
+			}
+			cyclesToBuy := targetCycles - safeCycleValue(status.CyclesRemaining)
+			if cyclesToBuy > 0 {
+				order, err = s.orderCycles(ctx, req.FromAddress, cyclesToBuy)
+				if err != nil {
+					return nil, err
+				}
+				if s.cfg.PostOrderWait.Duration() > 0 {
+					select {
+					case <-time.After(s.cfg.PostOrderWait.Duration()):
+					case <-ctx.Done():
+						return nil, ctx.Err()
+					}
+				}
+				status, _, err = s.ensureHostMode(ctx, req.FromAddress, req.CallbackURL)
+				if err != nil {
+					return nil, err
+				}
+			}
+		}
+	}
+
+	if status != nil {
+		cyclesAfter = status.CyclesRemaining
+	}
+
+	resp := &EnsureEnergyResponse{
+		FromAddress:       req.FromAddress,
+		ToAddress:         req.ToAddress,
+		Amount:            amount,
+		AddressAdded:      addressAdded,
+		RecommendedEnergy: transfer.RecommendedEnergy,
+		EnergyNeeded:      energyNeeded,
+		CyclesBefore:      cyclesBefore,
+		CyclesAfter:       cyclesAfter,
+		Analysis:          transfer,
+		OrderRaw:          order,
+		Status:            status,
+	}
+
+	if order != nil {
+		resp.CyclesPurchased = order.CyclesPurchased
+		resp.TotalCycles = order.TotalCycles
+		resp.OrderID = order.OrderID
+		resp.TotalCost = order.TotalCost
+		resp.OrderStatus = order.Status
+		resp.NextDelegation = order.NextDelegation
+	}
+
+	return resp, nil
+}
+
+func (s *EnergyService) ensureHostMode(ctx context.Context, address, callbackURL string) (*netts.AddressStatus, bool, error) {
+	status, err := s.nettsClient.GetAddressStatus(ctx, address)
+	if err == nil {
+		return status, false, nil
+	}
+	if !errors.Is(err, netts.ErrAddressNotFound) {
+		return nil, false, fmt.Errorf("get address status: %w", err)
+	}
+	if !s.cfg.AutoAddHost {
+		return nil, false, fmt.Errorf("address %s not in host mode and autoAddHost disabled", address)
+	}
+	if _, err := s.nettsClient.AddHostAddress(ctx, address, callbackURL); err != nil {
+		return nil, false, fmt.Errorf("add host address: %w", err)
+	}
+	s.logger.InfoContext(ctx, "address added to Host Mode", "address", address)
+
+	status, err = s.nettsClient.GetAddressStatus(ctx, address)
+	if err != nil {
+		return nil, true, fmt.Errorf("get address status after add: %w", err)
+	}
+	return status, true, nil
+}
+
+func (s *EnergyService) orderCycles(ctx context.Context, address string, cycles int) (*netts.OrderResult, error) {
+	if cycles <= 0 {
+		return nil, nil
+	}
+	if cycles > 1000 {
+		cycles = 1000
+	}
+	order, err := s.nettsClient.OrderCycles(ctx, address, cycles)
+	if err != nil {
+		return nil, fmt.Errorf("order cycles: %w", err)
+	}
+	s.logger.InfoContext(ctx, "cycles ordered",
+		"address", address,
+		"cycles_purchased", order.CyclesPurchased,
+		"total_cycles", order.TotalCycles,
+		"order_id", order.OrderID,
+	)
+	return order, nil
+}
+
+func (s *EnergyService) validateRequest(req EnsureEnergyRequest) error {
+	if !tronAddressPattern.MatchString(req.FromAddress) {
+		return fmt.Errorf("invalid from_address: %s", req.FromAddress)
+	}
+	if !tronAddressPattern.MatchString(req.ToAddress) {
+		return fmt.Errorf("invalid to_address: %s", req.ToAddress)
+	}
+	return nil
+}
+
+func shouldOrderCycles(status *netts.AddressStatus, minCycles int) bool {
+	if status == nil {
+		return true
+	}
+	if status.CyclesRemaining < 0 {
+		// Infinity mode (-1) requires no manual orders.
+		return false
+	}
+	return status.CyclesRemaining < minCycles
+}
+
+func safeCycleValue(value int) int {
+	if value < 0 {
+		return 0
+	}
+	return value
+}
diff --git a/internal/service/energy_service_test.go b/internal/service/energy_service_test.go
new file mode 100644
index 0000000..4191905
--- /dev/null
+++ b/internal/service/energy_service_test.go
@@ -0,0 +1,183 @@
+package service
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+
+	appconfig "github.com/D36u99er/bc-netts-energy/internal/config"
+	"github.com/D36u99er/bc-netts-energy/internal/netts"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"log/slog"
+)
+
+func TestEnsureEnergyAddsAddressAndOrdersCycles(t *testing.T) {
+	mock := &mockNettsClient{
+		analyzeData: &netts.AnalyzeUSDTData{
+			TransferDetails: netts.TransferDetails{
+				RecommendedEnergy: 131000,
+				EnergyNeeded:      131000,
+			},
+		},
+		statusResponses: []statusResponse{
+			{err: netts.ErrAddressNotFound},
+			{status: &netts.AddressStatus{CyclesRemaining: 2}},
+			{status: &netts.AddressStatus{CyclesRemaining: 5}},
+		},
+		orderResult: &netts.OrderResult{
+			CyclesPurchased: 3,
+			TotalCycles:     5,
+			OrderID:         "ORD-123",
+			Status:          "confirmed",
+			TotalCost:       7.5,
+		},
+	}
+
+	cfg := appconfig.EnergyConfig{
+		AutoAddHost:         true,
+		MinCycles:           3,
+		TargetCycles:        5,
+		PostOrderWait:       appconfig.Duration(0),
+		DefaultAnalyzeValue: "100.00",
+	}
+
+	logger := slog.New(slog.NewTextHandler(ioDiscard{}, &slog.HandlerOptions{Level: slog.LevelDebug}))
+	svc := NewEnergyService(cfg, mock, logger)
+
+	resp, err := svc.EnsureEnergy(context.Background(), EnsureEnergyRequest{
+		FromAddress: "TQn9Y2khEsLJW1ChVWFMSMeRDow5KcbLSE",
+		ToAddress:   "TUmyHQNzAkT6SrwThVvay7G4yfGZAyWhmy",
+		Amount:      "50.0",
+	})
+	require.NoError(t, err)
+
+	assert.True(t, resp.AddressAdded)
+	assert.Equal(t, 3, resp.CyclesPurchased)
+	assert.Equal(t, 5, resp.CyclesAfter)
+	assert.Equal(t, "ORD-123", resp.OrderID)
+	assert.Equal(t, 131000, resp.RecommendedEnergy)
+	assert.Equal(t, 131000, resp.EnergyNeeded)
+
+	assert.Equal(t, 1, mock.addCalls)
+	assert.Equal(t, []int{3}, mock.orderCalls)
+	assert.Equal(t, 0, len(mock.statusResponses))
+}
+
+func TestEnsureEnergyFailsWhenAutoAddDisabled(t *testing.T) {
+	mock := &mockNettsClient{
+		analyzeData: &netts.AnalyzeUSDTData{TransferDetails: netts.TransferDetails{RecommendedEnergy: 1000}},
+		statusResponses: []statusResponse{
+			{err: netts.ErrAddressNotFound},
+		},
+	}
+
+	cfg := appconfig.EnergyConfig{
+		AutoAddHost:  false,
+		MinCycles:    2,
+		TargetCycles: 4,
+	}
+
+	logger := slog.New(slog.NewTextHandler(ioDiscard{}, nil))
+	svc := NewEnergyService(cfg, mock, logger)
+
+	_, err := svc.EnsureEnergy(context.Background(), EnsureEnergyRequest{
+		FromAddress: "TQn9Y2khEsLJW1ChVWFMSMeRDow5KcbLSE",
+		ToAddress:   "TUmyHQNzAkT6SrwThVvay7G4yfGZAyWhmy",
+	})
+	require.Error(t, err)
+	assert.Equal(t, 0, mock.addCalls)
+}
+
+func TestEnsureEnergySkipsOrderWhenSufficientCycles(t *testing.T) {
+	mock := &mockNettsClient{
+		analyzeData: &netts.AnalyzeUSDTData{
+			TransferDetails: netts.TransferDetails{
+				RecommendedEnergy: 90000,
+				EnergyNeeded:      80000,
+			},
+		},
+		statusResponses: []statusResponse{
+			{status: &netts.AddressStatus{CyclesRemaining: 5}},
+		},
+	}
+
+	cfg := appconfig.EnergyConfig{
+		AutoAddHost:  true,
+		MinCycles:    3,
+		TargetCycles: 6,
+	}
+
+	logger := slog.New(slog.NewTextHandler(ioDiscard{}, nil))
+	svc := NewEnergyService(cfg, mock, logger)
+
+	resp, err := svc.EnsureEnergy(context.Background(), EnsureEnergyRequest{
+		FromAddress: "TQn9Y2khEsLJW1ChVWFMSMeRDow5KcbLSE",
+		ToAddress:   "TUmyHQNzAkT6SrwThVvay7G4yfGZAyWhmy",
+	})
+	require.NoError(t, err)
+
+	assert.False(t, resp.AddressAdded)
+	assert.Equal(t, 0, resp.CyclesPurchased)
+	assert.Equal(t, 5, resp.CyclesAfter)
+	assert.Empty(t, mock.orderCalls)
+}
+
+type statusResponse struct {
+	status *netts.AddressStatus
+	err    error
+}
+
+type mockNettsClient struct {
+	analyzeData     *netts.AnalyzeUSDTData
+	statusResponses []statusResponse
+	orderResult     *netts.OrderResult
+
+	addCalls   int
+	orderCalls []int
+}
+
+func (m *mockNettsClient) AnalyzeUSDT(ctx context.Context, req netts.AnalyzeUSDTRequest) (*netts.AnalyzeUSDTData, error) {
+	if m.analyzeData == nil {
+		return nil, errors.New("no analysis data")
+	}
+	return m.analyzeData, nil
+}
+
+func (m *mockNettsClient) GetAddressStatus(ctx context.Context, address string) (*netts.AddressStatus, error) {
+	if len(m.statusResponses) == 0 {
+		return nil, errors.New("no status response")
+	}
+	resp := m.statusResponses[0]
+	m.statusResponses = m.statusResponses[1:]
+	return resp.status, resp.err
+}
+
+func (m *mockNettsClient) AddHostAddress(ctx context.Context, address, callback string) (*netts.AddAddressResult, error) {
+	m.addCalls++
+	return &netts.AddAddressResult{
+		Address:     address,
+		CallbackURL: callback,
+		Timestamp:   time.Now().UTC().Format(time.RFC3339),
+	}, nil
+}
+
+func (m *mockNettsClient) OrderCycles(ctx context.Context, address string, cycles int) (*netts.OrderResult, error) {
+	m.orderCalls = append(m.orderCalls, cycles)
+	if m.orderResult != nil {
+		return m.orderResult, nil
+	}
+	return &netts.OrderResult{
+		CyclesPurchased: cycles,
+		TotalCycles:     cycles,
+		OrderID:         "ORD",
+		Status:          "confirmed",
+	}, nil
+}
+
+type ioDiscard struct{}
+
+func (ioDiscard) Write(p []byte) (int, error) { return len(p), nil }
diff --git a/pkg/errors/api_error.go b/pkg/errors/api_error.go
new file mode 100644
index 0000000..23b61c0
--- /dev/null
+++ b/pkg/errors/api_error.go
@@ -0,0 +1,36 @@
+package errors
+
+import "fmt"
+
+// APIError represents a structured error from an upstream API.
+type APIError struct {
+	Code       int
+	Message    string
+	HTTPStatus int
+}
+
+func (e *APIError) Error() string {
+	if e == nil {
+		return "<nil>"
+	}
+	if e.HTTPStatus > 0 {
+		return fmt.Sprintf("api error: status=%d code=%d message=%s", e.HTTPStatus, e.Code, e.Message)
+	}
+	return fmt.Sprintf("api error: code=%d message=%s", e.Code, e.Message)
+}
+
+// Temporary returns true when the error is potentially recoverable.
+func (e *APIError) Temporary() bool {
+	if e == nil {
+		return false
+	}
+	if e.HTTPStatus >= 500 {
+		return true
+	}
+	switch e.Code {
+	case 429:
+		return true
+	default:
+		return false
+	}
+}