diff --git a/README.md b/README.md
index cff95b5..6c5dcee 100644
--- a/README.md
+++ b/README.md
@@ -7,6 +7,7 @@ Shared Go-библиотека для микросервисов портала.
 - `db/` — pgxpool init + slow-query tracer. Заменяет идентичный код в 9 сервисах.
 - `middleware/` — `InternalAuth` (X-Internal-Key + X-User-*) + хелперы для кастомных заголовков.
 - `portal/` — HTTP-клиент portal-сервиса: directory с кэшем+stale fallback, notifications, deactivate user.
+- `audit/` — общий контракт business-audit событий и клиент отправки в Portal.
 
 ## Использование
 
@@ -14,6 +15,7 @@ Shared Go-библиотека для микросервисов портала.
 
 ```go
 import (
+    "gitea.estateliga.work/admin/portal-common/audit"
     "gitea.estateliga.work/admin/portal-common/db"
     "gitea.estateliga.work/admin/portal-common/middleware"
     "gitea.estateliga.work/admin/portal-common/portal"
@@ -25,8 +27,31 @@ r := chi.NewRouter()
 r.Use(middleware.InternalAuth(cfg.InternalAPIKey))
 
 portalCli := portal.New(cfg.PortalBaseURL, cfg.PortalAPIKey)
+auditCli := audit.NewClient(cfg.PortalBaseURL, cfg.PortalAPIKey)
+_ = auditCli.Send(ctx, audit.Event{
+    Action:     "tasks.task_create",
+    EntityType: "task",
+    EntityID:   taskID,
+    UserID:     actorID,
+    UserName:   actorName,
+    Details: map[string]any{
+        "request_id": requestID,
+    },
+})
 ```
 
+## Business audit vocabulary
+
+События именуются в формате `<service>.<entity>_<verb>`:
+
+- `service`: короткий код сервиса (`tasks`, `files`, `tg`, `pf`, `telephony`, `portal`).
+- `entity`: бизнес-сущность (`task`, `node`, `channel`, `project`, `call`).
+- `verb`: действие в прошедшем бизнес-смысле или команда (`create`, `update`, `delete`, `retry`, `share`, `move`).
+
+В `Details` можно класть диагностический контекст (`request_id`, `scope`,
+`status`, `error_code`), но нельзя класть токены, пароли и API-ключи. Пакет
+`audit` дополнительно вырезает чувствительные ключи перед отправкой.
+
 ## Dev-режим (без push в Gitea)
 
 В `go.mod` сервиса добавить `replace`:
diff --git a/audit/audit.go b/audit/audit.go
new file mode 100644
index 0000000..67ab74a
--- /dev/null
+++ b/audit/audit.go
@@ -0,0 +1,158 @@
+// Package audit defines the shared business-audit contract used by Portal
+// microservices.
+package audit
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"regexp"
+	"strings"
+	"time"
+)
+
+const (
+	MaxTokenLength  = 80
+	MaxDetailsBytes = 16 * 1024
+)
+
+var (
+	tokenRe     = regexp.MustCompile(`^[a-z][a-z0-9_.-]{1,79}$`)
+	secretKeyRe = regexp.MustCompile(`(?i)token|secret|password|api_?key|bearer|authorization|webhook_url|bitrix`)
+)
+
+// Event is the stable wire contract for business-audit events.
+type Event struct {
+	Action     string         `json:"action"`
+	EntityType string         `json:"entity_type"`
+	EntityID   string         `json:"entity_id,omitempty"`
+	UserID     string         `json:"user_id,omitempty"`
+	UserName   string         `json:"user_name,omitempty"`
+	Details    map[string]any `json:"details,omitempty"`
+	IPAddress  string         `json:"ip_address,omitempty"`
+}
+
+// Normalize trims fields and redacts sensitive values in Details.
+func (e Event) Normalize() Event {
+	e.Action = strings.TrimSpace(e.Action)
+	e.EntityType = strings.TrimSpace(e.EntityType)
+	e.EntityID = truncateRunes(strings.TrimSpace(e.EntityID), 255)
+	e.UserID = strings.TrimSpace(e.UserID)
+	e.UserName = strings.TrimSpace(e.UserName)
+	e.IPAddress = strings.TrimSpace(e.IPAddress)
+	if e.Details != nil {
+		if redacted, ok := RedactSecrets(e.Details).(map[string]any); ok {
+			e.Details = redacted
+		}
+	}
+	return e
+}
+
+// Validate checks the event shape before it is sent to Portal.
+func (e Event) Validate() error {
+	e = e.Normalize()
+	if !ValidToken(e.Action) {
+		return fmt.Errorf("invalid audit action %q", e.Action)
+	}
+	if !ValidToken(e.EntityType) {
+		return fmt.Errorf("invalid audit entity_type %q", e.EntityType)
+	}
+	if e.Details != nil && detailsTooLarge(e.Details) {
+		return fmt.Errorf("audit details exceed %d bytes", MaxDetailsBytes)
+	}
+	return nil
+}
+
+func ValidToken(value string) bool {
+	value = strings.TrimSpace(value)
+	return len(value) <= MaxTokenLength && tokenRe.MatchString(value)
+}
+
+// RedactSecrets recursively replaces values for sensitive JSON keys.
+func RedactSecrets(v any) any {
+	switch x := v.(type) {
+	case map[string]any:
+		out := make(map[string]any, len(x))
+		for k, val := range x {
+			if secretKeyRe.MatchString(k) {
+				out[k] = "***"
+			} else {
+				out[k] = RedactSecrets(val)
+			}
+		}
+		return out
+	case []any:
+		out := make([]any, len(x))
+		for i, val := range x {
+			out[i] = RedactSecrets(val)
+		}
+		return out
+	default:
+		return v
+	}
+}
+
+type Client struct {
+	baseURL string
+	apiKey  string
+	hc      *http.Client
+}
+
+func NewClient(baseURL, apiKey string) *Client {
+	return &Client{
+		baseURL: strings.TrimRight(baseURL, "/"),
+		apiKey:  apiKey,
+		hc:      &http.Client{Timeout: 5 * time.Second},
+	}
+}
+
+func (c *Client) Enabled() bool {
+	return c != nil && c.baseURL != "" && c.apiKey != ""
+}
+
+func (c *Client) Send(ctx context.Context, event Event) error {
+	if !c.Enabled() {
+		return errors.New("audit client disabled")
+	}
+	event = event.Normalize()
+	if err := event.Validate(); err != nil {
+		return err
+	}
+	body, err := json.Marshal(event)
+	if err != nil {
+		return fmt.Errorf("marshal audit event: %w", err)
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+"/api/internal/audit/events", bytes.NewReader(body))
+	if err != nil {
+		return fmt.Errorf("new audit request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("X-Internal-Key", c.apiKey)
+	resp, err := c.hc.Do(req)
+	if err != nil {
+		return fmt.Errorf("send audit event: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+	if resp.StatusCode >= 300 {
+		respBody, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
+		return fmt.Errorf("portal audit returned %d: %s", resp.StatusCode, string(respBody))
+	}
+	return nil
+}
+
+func detailsTooLarge(value any) bool {
+	raw, err := json.Marshal(value)
+	return err != nil || len(raw) > MaxDetailsBytes
+}
+
+func truncateRunes(value string, max int) string {
+	runes := []rune(value)
+	if len(runes) <= max {
+		return value
+	}
+	return string(runes[:max])
+}
diff --git a/audit/audit_test.go b/audit/audit_test.go
new file mode 100644
index 0000000..19cbaf3
--- /dev/null
+++ b/audit/audit_test.go
@@ -0,0 +1,85 @@
+package audit
+
+import "testing"
+
+func TestEventNormalizeRedactsSecretsAndTruncatesEntityID(t *testing.T) {
+	event := Event{
+		Action:     " files.share_create ",
+		EntityType: " file_node ",
+		EntityID:   longString("x", 300),
+		Details: map[string]any{
+			"request_id": "rid-1",
+			"password":   "plain",
+			"nested": map[string]any{
+				"api_key": "secret",
+			},
+			"items": []any{
+				map[string]any{"token": "secret"},
+			},
+		},
+	}
+
+	got := event.Normalize()
+	if got.Action != "files.share_create" {
+		t.Fatalf("action was not trimmed: %q", got.Action)
+	}
+	if got.EntityType != "file_node" {
+		t.Fatalf("entity type was not trimmed: %q", got.EntityType)
+	}
+	if len([]rune(got.EntityID)) != 255 {
+		t.Fatalf("entity id was not truncated, got %d", len([]rune(got.EntityID)))
+	}
+	if got.Details["password"] != "***" {
+		t.Fatalf("password was not redacted: %#v", got.Details["password"])
+	}
+	nested := got.Details["nested"].(map[string]any)
+	if nested["api_key"] != "***" {
+		t.Fatalf("nested api_key was not redacted: %#v", nested["api_key"])
+	}
+	items := got.Details["items"].([]any)
+	if items[0].(map[string]any)["token"] != "***" {
+		t.Fatalf("array token was not redacted: %#v", items[0])
+	}
+}
+
+func TestEventValidate(t *testing.T) {
+	valid := Event{Action: "tasks.task_create", EntityType: "task"}
+	if err := valid.Validate(); err != nil {
+		t.Fatalf("valid event rejected: %v", err)
+	}
+
+	invalidAction := Event{Action: "Task Created", EntityType: "task"}
+	if err := invalidAction.Validate(); err == nil {
+		t.Fatal("invalid action was accepted")
+	}
+
+	invalidEntity := Event{Action: "tasks.task_create", EntityType: "1task"}
+	if err := invalidEntity.Validate(); err == nil {
+		t.Fatal("invalid entity type was accepted")
+	}
+}
+
+func TestValidToken(t *testing.T) {
+	tests := map[string]bool{
+		"files.node_move":                 true,
+		"ai.job-retry":                    true,
+		"a1":                              true,
+		"A1":                              false,
+		"a":                               false,
+		"files node":                      false,
+		longString("a", MaxTokenLength+1): false,
+	}
+	for value, want := range tests {
+		if got := ValidToken(value); got != want {
+			t.Fatalf("ValidToken(%q) = %v, want %v", value, got, want)
+		}
+	}
+}
+
+func longString(ch string, n int) string {
+	out := ""
+	for range n {
+		out += ch
+	}
+	return out
+}