diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..4da58d3
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,45 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  go:
+    name: Go (api)
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: api
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "1.23"
+          cache-dependency-path: api/go.sum
+      - name: Verify gofmt
+        run: test -z "$(gofmt -l .)"
+      - run: go vet ./...
+      - run: go build ./...
+      - run: go test ./...
+
+  python:
+    name: Python (ingestion)
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: ingestion
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+      - name: Install
+        run: pip install -e ".[dev]"
+      - name: Ruff lint
+        run: ruff check .
+      - name: Ruff format check
+        run: ruff format --check .
+      - name: Pytest
+        run: pytest -q
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..843f600
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,25 @@
+# Go
+/api/server
+*.test
+*.out
+
+# Python
+__pycache__/
+*.py[cod]
+.venv/
+.pytest_cache/
+.ruff_cache/
+*.egg-info/
+build/
+dist/
+
+# Env / local
+.env
+.env.*
+!.env.example
+
+# OS / editors
+.DS_Store
+*.swp
+.idea/
+.vscode/
diff --git a/api/Dockerfile b/api/Dockerfile
new file mode 100644
index 0000000..b92be17
--- /dev/null
+++ b/api/Dockerfile
@@ -0,0 +1,13 @@
+# Build stage
+FROM golang:1.23-alpine AS build
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 go build -o /out/server ./cmd/server
+
+# Runtime stage
+FROM gcr.io/distroless/static-debian12
+COPY --from=build /out/server /server
+EXPOSE 8080
+ENTRYPOINT ["/server"]
diff --git a/api/cmd/server/main.go b/api/cmd/server/main.go
new file mode 100644
index 0000000..fe1e0c9
--- /dev/null
+++ b/api/cmd/server/main.go
@@ -0,0 +1,26 @@
+// Command server starts the OpenGoods public read-only API.
+package main
+
+import (
+	"log"
+	"net/http"
+	"time"
+
+	"github.com/baicai2026-baicai/goods/api/internal/config"
+	"github.com/baicai2026-baicai/goods/api/internal/handler"
+)
+
+func main() {
+	cfg := config.Load()
+
+	srv := &http.Server{
+		Addr:              cfg.Addr,
+		Handler:           handler.Router(),
+		ReadHeaderTimeout: 10 * time.Second,
+	}
+
+	log.Printf("OpenGoods API listening on %s", cfg.Addr)
+	if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+		log.Fatalf("server error: %v", err)
+	}
+}
diff --git a/api/go.mod b/api/go.mod
new file mode 100644
index 0000000..64268e5
--- /dev/null
+++ b/api/go.mod
@@ -0,0 +1,5 @@
+module github.com/baicai2026-baicai/goods/api
+
+go 1.23.4
+
+require github.com/go-chi/chi/v5 v5.1.0
diff --git a/api/go.sum b/api/go.sum
new file mode 100644
index 0000000..823cdbb
--- /dev/null
+++ b/api/go.sum
@@ -0,0 +1,2 @@
+github.com/go-chi/chi/v5 v5.1.0 h1:acVI1TYaD+hhedDJ3r54HyA6sExp3HfXq7QWEEY/xMw=
+github.com/go-chi/chi/v5 v5.1.0/go.mod h1:DslCQbL2OYiznFReuXYUmQ2hGd1aDpCnlMNITLSKoi8=
diff --git a/api/internal/config/config.go b/api/internal/config/config.go
new file mode 100644
index 0000000..6bfe038
--- /dev/null
+++ b/api/internal/config/config.go
@@ -0,0 +1,30 @@
+package config
+
+import (
+	"os"
+)
+
+// Config holds runtime configuration for the OpenGoods API server.
+// Values are read from environment variables with sensible defaults so the
+// server can boot in a local Docker Compose setup without extra configuration.
+type Config struct {
+	Addr        string
+	DatabaseURL string
+	RedisURL    string
+}
+
+// Load reads configuration from the environment.
+func Load() Config {
+	return Config{
+		Addr:        getenv("OPENGOODS_ADDR", ":8080"),
+		DatabaseURL: getenv("OPENGOODS_DATABASE_URL", "postgres://opengoods:opengoods@localhost:5432/opengoods?sslmode=disable"),
+		RedisURL:    getenv("OPENGOODS_REDIS_URL", "redis://localhost:6379/0"),
+	}
+}
+
+func getenv(key, fallback string) string {
+	if v, ok := os.LookupEnv(key); ok && v != "" {
+		return v
+	}
+	return fallback
+}
diff --git a/api/internal/handler/handler.go b/api/internal/handler/handler.go
new file mode 100644
index 0000000..96b255e
--- /dev/null
+++ b/api/internal/handler/handler.go
@@ -0,0 +1,68 @@
+// Package handler wires up the public, read-only OpenGoods HTTP API.
+//
+// The OpenGoods service is a public-good product information API: it only
+// collects and serves product facts. It exposes no purchase, checkout, or
+// commerce endpoints by design.
+package handler
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
+)
+
+// APIVersion is the current public API version prefix.
+const APIVersion = "v1"
+
+// Router builds the top-level HTTP handler with middleware and routes mounted.
+func Router() http.Handler {
+	r := chi.NewRouter()
+	r.Use(middleware.RequestID)
+	r.Use(middleware.RealIP)
+	r.Use(middleware.Recoverer)
+
+	r.Get("/healthz", Healthz)
+
+	r.Route("/api/"+APIVersion, func(r chi.Router) {
+		r.Route("/products", func(r chi.Router) {
+			r.Get("/barcode/{gtin}", notImplemented)
+			r.Get("/search", notImplemented)
+			r.Get("/{id}", notImplemented)
+			r.Get("/{id}/nutriments", notImplemented)
+			r.Get("/{id}/msrp", notImplemented)
+		})
+		r.Get("/brands", notImplemented)
+		r.Get("/categories", notImplemented)
+		r.Get("/sources/{id}", notImplemented)
+	})
+
+	return r
+}
+
+// Healthz reports liveness of the service.
+func Healthz(w http.ResponseWriter, r *http.Request) {
+	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
+}
+
+// notImplemented is a placeholder for endpoints scoped to later milestones.
+func notImplemented(w http.ResponseWriter, r *http.Request) {
+	writeError(w, r, http.StatusNotImplemented, "not_implemented", "endpoint not implemented yet")
+}
+
+func writeJSON(w http.ResponseWriter, status int, body any) {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(body)
+}
+
+func writeError(w http.ResponseWriter, r *http.Request, status int, code, message string) {
+	writeJSON(w, status, map[string]any{
+		"error": map[string]string{
+			"code":       code,
+			"message":    message,
+			"request_id": middleware.GetReqID(r.Context()),
+		},
+	})
+}
diff --git a/api/internal/handler/handler_test.go b/api/internal/handler/handler_test.go
new file mode 100644
index 0000000..82aaae6
--- /dev/null
+++ b/api/internal/handler/handler_test.go
@@ -0,0 +1,38 @@
+package handler
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestHealthz(t *testing.T) {
+	req := httptest.NewRequest(http.MethodGet, "/healthz", nil)
+	rec := httptest.NewRecorder()
+
+	Router().ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("expected status %d, got %d", http.StatusOK, rec.Code)
+	}
+
+	var body map[string]string
+	if err := json.NewDecoder(rec.Body).Decode(&body); err != nil {
+		t.Fatalf("failed to decode body: %v", err)
+	}
+	if body["status"] != "ok" {
+		t.Fatalf("expected status ok, got %q", body["status"])
+	}
+}
+
+func TestProductEndpointNotImplemented(t *testing.T) {
+	req := httptest.NewRequest(http.MethodGet, "/api/"+APIVersion+"/products/barcode/3017624010701", nil)
+	rec := httptest.NewRecorder()
+
+	Router().ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusNotImplemented {
+		t.Fatalf("expected status %d, got %d", http.StatusNotImplemented, rec.Code)
+	}
+}
diff --git a/docker-compose.yml b/docker-compose.yml
new file mode 100644
index 0000000..21edc51
--- /dev/null
+++ b/docker-compose.yml
@@ -0,0 +1,61 @@
+services:
+  postgres:
+    image: postgres:16-alpine
+    environment:
+      POSTGRES_USER: opengoods
+      POSTGRES_PASSWORD: opengoods
+      POSTGRES_DB: opengoods
+    ports:
+      - "5432:5432"
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U opengoods"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+
+  redis:
+    image: redis:7-alpine
+    ports:
+      - "6379:6379"
+    healthcheck:
+      test: ["CMD", "redis-cli", "ping"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+
+  minio:
+    image: minio/minio:latest
+    command: server /data --console-address ":9001"
+    environment:
+      MINIO_ROOT_USER: opengoods
+      MINIO_ROOT_PASSWORD: opengoods123
+    ports:
+      - "9000:9000"
+      - "9001:9001"
+    volumes:
+      - miniodata:/data
+    healthcheck:
+      test: ["CMD", "mc", "ready", "local"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+
+  api:
+    build: ./api
+    depends_on:
+      postgres:
+        condition: service_healthy
+      redis:
+        condition: service_healthy
+    environment:
+      OPENGOODS_ADDR: ":8080"
+      OPENGOODS_DATABASE_URL: "postgres://opengoods:opengoods@postgres:5432/opengoods?sslmode=disable"
+      OPENGOODS_REDIS_URL: "redis://redis:6379/0"
+    ports:
+      - "8080:8080"
+
+volumes:
+  pgdata:
+  miniodata:
diff --git a/docs/data-contract.md b/docs/data-contract.md
new file mode 100644
index 0000000..2843c11
--- /dev/null
+++ b/docs/data-contract.md
@@ -0,0 +1,36 @@
+# 数据契约 (Data Contract) v0.1
+
+本契约是 Go(API) 与 Python(ingestion) 两端共享的"事实约定"，避免两端对字段含义理解不一致。
+
+> 写入责任：**仅 Python (ingestion) 通过 ETL 写入数据库**；Go (API) **只读**。所有写入必须经过单位归一化与字段级溯源。
+
+## 1. 边界原则
+- 系统只采集与提供**客观商品信息**；不包含任何购买/交易语义的字段或端点。
+- 价格仅收录**官方建议零售价 (MSRP)** 的静态快照，必须带 `currency`/`region`/`source`/`effective_date`。
+
+## 2. 固定枚举
+| 字段 | 取值 |
+|------|------|
+| `product.status` | `active` / `merged` / `deprecated` |
+| `food_detail.nutrition_basis` | `per_100g` / `per_100ml` / `per_serving` |
+| `unit.dimension` | `mass` / `volume` / `energy` / `count` / `ratio` / `length` / `duration` |
+| `source.license` | `ODbL` / `CC0` / `proprietary` / ... |
+| `product_image.kind` | `front` / `ingredients` / `nutrition` / `other` |
+
+## 3. 单位规则
+- 数值字段同时保存**原始值 + 单位**与**归一化值 + 基准单位**（canonical）。
+- 质量 → `g`，体积 → `ml`，能量 → `kJ`（同时保留 `kcal`）。
+- 归一化逻辑由 `ingestion/opengoods/units.py` 提供（纯函数，含测试），换算因子是唯一事实来源。
+- 营养成分统一折算到品类模板规定的基准（`per_100g` / `per_100ml`）。
+
+## 4. 标识与可空性
+- `product.gtin`：8/12/13/14 位数字，可空（无条码商品），非空时全局唯一。
+- `product.quality_score` ∈ [0, 1]。
+- 货币用 ISO 4217（`CNY` 等），国家/地区用简短代码（`CN` 等）。
+
+## 5. 溯源 (Provenance)
+- 每条数据通过 `product_source` 记录来源、URL、贡献字段、抓取时间与原始快照。
+- 对外 API 在 `sources` 中透明返回来源与其许可。
+
+## 6. 版本
+- 本契约随 schema 演进版本化；任何 schema 变更需同步更新：迁移(SQL) + 本契约 + `docs/openapi.yaml`。
diff --git a/docs/disclaimer.md b/docs/disclaimer.md
new file mode 100644
index 0000000..bd6d18f
--- /dev/null
+++ b/docs/disclaimer.md
@@ -0,0 +1,11 @@
+# 免责声明 (Disclaimer)
+
+天工·商品标签 (OpenGoods) 是一个**公益信息平台**。
+
+- 本站**仅提供商品参数信息，不提供任何购买、下单、比价或导购服务**，不包含任何购买入口或交易链接。
+- 商品参数（成分、营养、规格等）来自多个数据来源并标注出处，可能存在误差或滞后；**请以商品实物标签为准**。
+- 价格字段仅为**官方建议零售价 (MSRP) 的历史快照**，标注来源与时间，实际售价以零售商为准，**不构成消费或购买建议**。
+- 本站不提供医疗、健康或功效宣称。
+- 数据按各来源许可使用（详见各条数据的 `sources` 字段与来源说明）；权利方可通过公开渠道申请更正或下架。
+
+> The OpenGoods service only collects and serves product information for public benefit. It provides **no purchase, checkout, price-comparison, or shopping-guide functionality**.
diff --git a/ingestion/opengoods/__init__.py b/ingestion/opengoods/__init__.py
new file mode 100644
index 0000000..5ab8be6
--- /dev/null
+++ b/ingestion/opengoods/__init__.py
@@ -0,0 +1,9 @@
+"""OpenGoods (天工·商品标签) ingestion package.
+
+Collects public product information from open data sources (e.g. Open Food
+Facts) and normalizes it into the OpenGoods database. This package only
+collects and processes product facts; it performs no purchase or commerce
+actions.
+"""
+
+__version__ = "0.1.0"
diff --git a/ingestion/opengoods/adapters/__init__.py b/ingestion/opengoods/adapters/__init__.py
new file mode 100644
index 0000000..0bca320
--- /dev/null
+++ b/ingestion/opengoods/adapters/__init__.py
@@ -0,0 +1,6 @@
+"""Source adapters.
+
+Each open data source (Open Food Facts, USDA FoodData Central, GS1, ...) gets
+its own adapter that fetches raw records and yields them for the ETL layer.
+Adapters must respect each source's robots.txt, rate limits and license.
+"""
diff --git a/ingestion/opengoods/adapters/base.py b/ingestion/opengoods/adapters/base.py
new file mode 100644
index 0000000..ac222b0
--- /dev/null
+++ b/ingestion/opengoods/adapters/base.py
@@ -0,0 +1,17 @@
+"""Base adapter protocol shared by all source adapters."""
+
+from __future__ import annotations
+
+from collections.abc import Iterator
+from typing import Protocol
+
+
+class SourceAdapter(Protocol):
+    """A source adapter fetches raw product records from one data source."""
+
+    #: Stable identifier of the source, e.g. "openfoodfacts".
+    source_name: str
+
+    def fetch(self) -> Iterator[dict]:
+        """Yield raw product records as dictionaries."""
+        ...
diff --git a/ingestion/opengoods/etl/__init__.py b/ingestion/opengoods/etl/__init__.py
new file mode 100644
index 0000000..56babb8
--- /dev/null
+++ b/ingestion/opengoods/etl/__init__.py
@@ -0,0 +1 @@
+"""ETL: clean, normalize, dedup and score raw records before loading."""
diff --git a/ingestion/opengoods/jobs/__init__.py b/ingestion/opengoods/jobs/__init__.py
new file mode 100644
index 0000000..11886e5
--- /dev/null
+++ b/ingestion/opengoods/jobs/__init__.py
@@ -0,0 +1 @@
+"""Jobs: seed import and scheduled incremental ingestion."""
diff --git a/ingestion/opengoods/units.py b/ingestion/opengoods/units.py
new file mode 100644
index 0000000..18f3591
--- /dev/null
+++ b/ingestion/opengoods/units.py
@@ -0,0 +1,97 @@
+"""Unit normalization for OpenGoods.
+
+Product parameters arrive in many units (g/kg/ml/L, kcal/kJ, ...). To make
+values comparable and searchable we store both the original value and a
+normalized value expressed in a canonical unit per dimension.
+
+This module is intentionally dependency-free and pure so it is easy to test.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from decimal import Decimal
+
+# Conversion factor maps each unit to its canonical unit within a dimension.
+# canonical_value = value * factor
+_FACTORS: dict[str, tuple[str, str, Decimal]] = {
+    # mass -> g
+    "mg": ("mass", "g", Decimal("0.001")),
+    "g": ("mass", "g", Decimal("1")),
+    "kg": ("mass", "g", Decimal("1000")),
+    # volume -> ml
+    "ml": ("volume", "ml", Decimal("1")),
+    "cl": ("volume", "ml", Decimal("10")),
+    "l": ("volume", "ml", Decimal("1000")),
+    # energy -> kJ
+    "kj": ("energy", "kJ", Decimal("1")),
+    "kcal": ("energy", "kJ", Decimal("4.184")),
+}
+
+# Alias map normalizes common spellings/locales to a canonical unit code.
+_ALIASES: dict[str, str] = {
+    "kgs": "kg",
+    "千克": "kg",
+    "公斤": "kg",
+    "克": "g",
+    "毫升": "ml",
+    "升": "l",
+    "L": "l",
+    "litre": "l",
+    "liter": "l",
+    "kj": "kj",
+    "kJ": "kj",
+    "千焦": "kj",
+    "千卡": "kcal",
+    "大卡": "kcal",
+}
+
+
+class UnitError(ValueError):
+    """Raised when a unit cannot be recognized."""
+
+
+@dataclass(frozen=True)
+class Normalized:
+    """Result of normalizing a (value, unit) pair to its canonical unit."""
+
+    value: Decimal
+    unit: str
+    dimension: str
+    canonical_value: Decimal
+    canonical_unit: str
+
+
+def canonical_unit_code(unit: str) -> str:
+    """Resolve a raw unit string to a known canonical unit code."""
+    cleaned = unit.strip()
+    cleaned = _ALIASES.get(cleaned, cleaned).lower()
+    if cleaned not in _FACTORS:
+        raise UnitError(f"unknown unit: {unit!r}")
+    return cleaned
+
+
+def normalize(value: Decimal | float | int | str, unit: str) -> Normalized:
+    """Normalize a value+unit to its canonical unit within its dimension."""
+    code = canonical_unit_code(unit)
+    dimension, canonical, factor = _FACTORS[code]
+    dec = value if isinstance(value, Decimal) else Decimal(str(value))
+    return Normalized(
+        value=dec,
+        unit=code,
+        dimension=dimension,
+        canonical_value=dec * factor,
+        canonical_unit=canonical,
+    )
+
+
+def kcal_to_kj(kcal: Decimal | float | int | str) -> Decimal:
+    """Convert energy in kcal to kJ (1 kcal = 4.184 kJ)."""
+    dec = kcal if isinstance(kcal, Decimal) else Decimal(str(kcal))
+    return dec * Decimal("4.184")
+
+
+def kj_to_kcal(kj: Decimal | float | int | str) -> Decimal:
+    """Convert energy in kJ to kcal."""
+    dec = kj if isinstance(kj, Decimal) else Decimal(str(kj))
+    return dec / Decimal("4.184")
diff --git a/ingestion/pyproject.toml b/ingestion/pyproject.toml
new file mode 100644
index 0000000..8be7953
--- /dev/null
+++ b/ingestion/pyproject.toml
@@ -0,0 +1,31 @@
+[project]
+name = "opengoods-ingestion"
+version = "0.1.0"
+description = "OpenGoods (天工·商品标签) ingestion & ETL: collect product data and load it into the OpenGoods database."
+requires-python = ">=3.11"
+dependencies = [
+    "httpx>=0.27",
+]
+
+[project.optional-dependencies]
+dev = [
+    "ruff>=0.6",
+    "pytest>=8.0",
+]
+
+[build-system]
+requires = ["setuptools>=68"]
+build-backend = "setuptools.build_meta"
+
+[tool.setuptools.packages.find]
+include = ["opengoods*"]
+
+[tool.ruff]
+line-length = 100
+target-version = "py311"
+
+[tool.ruff.lint]
+select = ["E", "F", "I", "UP", "B"]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
diff --git a/ingestion/tests/__init__.py b/ingestion/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/ingestion/tests/test_units.py b/ingestion/tests/test_units.py
new file mode 100644
index 0000000..cbaa012
--- /dev/null
+++ b/ingestion/tests/test_units.py
@@ -0,0 +1,47 @@
+from decimal import Decimal
+
+import pytest
+
+from opengoods.units import (
+    UnitError,
+    canonical_unit_code,
+    kcal_to_kj,
+    kj_to_kcal,
+    normalize,
+)
+
+
+def test_normalize_mass_kg_to_g():
+    result = normalize("1.5", "kg")
+    assert result.dimension == "mass"
+    assert result.canonical_unit == "g"
+    assert result.canonical_value == Decimal("1500.0")
+
+
+def test_normalize_volume_litre_alias():
+    result = normalize(2, "升")
+    assert result.dimension == "volume"
+    assert result.canonical_value == Decimal("2000")
+    assert result.canonical_unit == "ml"
+
+
+def test_normalize_energy_kcal_to_kj():
+    result = normalize("539", "kcal")
+    assert result.dimension == "energy"
+    assert result.canonical_unit == "kJ"
+    assert result.canonical_value == Decimal("539") * Decimal("4.184")
+
+
+def test_canonical_unit_code_alias():
+    assert canonical_unit_code("公斤") == "kg"
+    assert canonical_unit_code(" G ") == "g"
+
+
+def test_unknown_unit_raises():
+    with pytest.raises(UnitError):
+        normalize(1, "parsec")
+
+
+def test_energy_roundtrip():
+    assert kcal_to_kj(1) == Decimal("4.184")
+    assert kj_to_kcal(Decimal("4.184")) == Decimal("1")
diff --git a/migrations/README.md b/migrations/README.md
new file mode 100644
index 0000000..bf58d4e
--- /dev/null
+++ b/migrations/README.md
@@ -0,0 +1,3 @@
+# Database migrations (golang-migrate)
+
+SQL migrations live here from milestone M1. Format: `NNNN_description.up.sql` / `.down.sql`.