feat(packages): add shared-go package with httputil and envutil

Shared Go utilities for all ManaCore Go services:
- httputil: WriteJSON, WriteError, DecodeJSON
- envutil: Get, GetInt, GetBool, GetSlice
- 8 tests, all passing

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/shared-go/envutil/envutil.go

@@ -0,0 +1,44 @@
+// Package envutil provides shared environment variable helpers for ManaCore Go services.
+package envutil
+
+import (
+	"os"
+	"strconv"
+	"strings"
+)
+
+// Get returns an environment variable value or a fallback default.
+func Get(key, fallback string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return fallback
+}
+
+// GetInt returns an environment variable as int or a fallback default.
+func GetInt(key string, fallback int) int {
+	if v := os.Getenv(key); v != "" {
+		if i, err := strconv.Atoi(v); err == nil {
+			return i
+		}
+	}
+	return fallback
+}
+
+// GetBool returns an environment variable as bool or a fallback default.
+func GetBool(key string, fallback bool) bool {
+	if v := os.Getenv(key); v != "" {
+		if b, err := strconv.ParseBool(v); err == nil {
+			return b
+		}
+	}
+	return fallback
+}
+
+// GetSlice returns an environment variable as a comma-separated slice or a fallback default.
+func GetSlice(key string, fallback []string) []string {
+	if v := os.Getenv(key); v != "" {
+		return strings.Split(v, ",")
+	}
+	return fallback
+}

packages/shared-go/envutil/envutil_test.go

@@ -0,0 +1,63 @@
+package envutil
+
+import (
+	"os"
+	"testing"
+)
+
+func TestGet(t *testing.T) {
+	os.Setenv("TEST_GET_VAR", "hello")
+	defer os.Unsetenv("TEST_GET_VAR")
+
+	if v := Get("TEST_GET_VAR", "default"); v != "hello" {
+		t.Errorf("expected 'hello', got '%s'", v)
+	}
+	if v := Get("TEST_GET_MISSING", "default"); v != "default" {
+		t.Errorf("expected 'default', got '%s'", v)
+	}
+}
+
+func TestGetInt(t *testing.T) {
+	os.Setenv("TEST_INT_VAR", "42")
+	defer os.Unsetenv("TEST_INT_VAR")
+
+	if v := GetInt("TEST_INT_VAR", 0); v != 42 {
+		t.Errorf("expected 42, got %d", v)
+	}
+	if v := GetInt("TEST_INT_MISSING", 99); v != 99 {
+		t.Errorf("expected 99, got %d", v)
+	}
+
+	os.Setenv("TEST_INT_INVALID", "abc")
+	defer os.Unsetenv("TEST_INT_INVALID")
+	if v := GetInt("TEST_INT_INVALID", 7); v != 7 {
+		t.Errorf("expected fallback 7 for invalid, got %d", v)
+	}
+}
+
+func TestGetBool(t *testing.T) {
+	os.Setenv("TEST_BOOL_VAR", "true")
+	defer os.Unsetenv("TEST_BOOL_VAR")
+
+	if v := GetBool("TEST_BOOL_VAR", false); !v {
+		t.Error("expected true")
+	}
+	if v := GetBool("TEST_BOOL_MISSING", true); !v {
+		t.Error("expected default true")
+	}
+}
+
+func TestGetSlice(t *testing.T) {
+	os.Setenv("TEST_SLICE_VAR", "a,b,c")
+	defer os.Unsetenv("TEST_SLICE_VAR")
+
+	v := GetSlice("TEST_SLICE_VAR", nil)
+	if len(v) != 3 || v[0] != "a" || v[2] != "c" {
+		t.Errorf("expected [a,b,c], got %v", v)
+	}
+
+	v = GetSlice("TEST_SLICE_MISSING", []string{"x"})
+	if len(v) != 1 || v[0] != "x" {
+		t.Errorf("expected [x], got %v", v)
+	}
+}

packages/shared-go/go.mod

@@ -0,0 +1,3 @@
+module github.com/manacore/shared-go
+
+go 1.25.0

packages/shared-go/httputil/httputil.go

@@ -0,0 +1,36 @@
+// Package httputil provides shared HTTP handler utilities for ManaCore Go services.
+package httputil
+
+import (
+	"encoding/json"
+	"net/http"
+	"time"
+)
+
+// WriteJSON writes a JSON response with the given status code.
+func WriteJSON(w http.ResponseWriter, status int, data any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	json.NewEncoder(w).Encode(data)
+}
+
+// WriteError writes a standardized error JSON response.
+func WriteError(w http.ResponseWriter, status int, message string) {
+	WriteJSON(w, status, map[string]any{
+		"success": false,
+		"error": map[string]any{
+			"statusCode": status,
+			"message":    message,
+			"timestamp":  time.Now().UTC().Format(time.RFC3339),
+		},
+	})
+}
+
+// DecodeJSON decodes a JSON request body with a size limit.
+func DecodeJSON(w http.ResponseWriter, r *http.Request, dst any, maxBytes int64) bool {
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, maxBytes)).Decode(dst); err != nil {
+		WriteError(w, http.StatusBadRequest, "invalid request body")
+		return false
+	}
+	return true
+}

packages/shared-go/httputil/httputil_test.go

@@ -0,0 +1,68 @@
+package httputil
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func TestWriteJSON(t *testing.T) {
+	w := httptest.NewRecorder()
+	WriteJSON(w, http.StatusOK, map[string]string{"key": "value"})
+
+	if w.Code != http.StatusOK {
+		t.Errorf("expected 200, got %d", w.Code)
+	}
+	if ct := w.Header().Get("Content-Type"); ct != "application/json" {
+		t.Errorf("expected application/json, got %s", ct)
+	}
+	if !strings.Contains(w.Body.String(), `"key":"value"`) {
+		t.Errorf("unexpected body: %s", w.Body.String())
+	}
+}
+
+func TestWriteError(t *testing.T) {
+	w := httptest.NewRecorder()
+	WriteError(w, http.StatusBadRequest, "test error")
+
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("expected 400, got %d", w.Code)
+	}
+	body := w.Body.String()
+	if !strings.Contains(body, `"message":"test error"`) {
+		t.Errorf("unexpected body: %s", body)
+	}
+	if !strings.Contains(body, `"success":false`) {
+		t.Errorf("missing success:false in body: %s", body)
+	}
+}
+
+func TestDecodeJSON(t *testing.T) {
+	var dst struct {
+		Name string `json:"name"`
+	}
+
+	r := httptest.NewRequest("POST", "/", strings.NewReader(`{"name":"test"}`))
+	w := httptest.NewRecorder()
+
+	if !DecodeJSON(w, r, &dst, 1<<20) {
+		t.Error("expected decode to succeed")
+	}
+	if dst.Name != "test" {
+		t.Errorf("expected 'test', got '%s'", dst.Name)
+	}
+}
+
+func TestDecodeJSON_Invalid(t *testing.T) {
+	var dst struct{}
+	r := httptest.NewRequest("POST", "/", strings.NewReader(`invalid`))
+	w := httptest.NewRecorder()
+
+	if DecodeJSON(w, r, &dst, 1<<20) {
+		t.Error("expected decode to fail")
+	}
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("expected 400, got %d", w.Code)
+	}
+}