authz_client/CLAUDE.md

# authz_client

Shared Go library for authorization service client integration.

## Shared Documentation

@../docs/claude/architecture.md
@../docs/claude/go-services.md
@../docs/claude/conventions.md

## Library Information

### Purpose

Provides a client for the authz-service, handling privilege management for users across companies. Used by all microservices that need to check user permissions.

### Usage

```go
import client "gitea.unbound.se/shiny/authz_client"

// Create handler with options
handler := client.New(client.WithBaseURL("http://authz-service"))

// Check user privileges
privileges := handler.Get(email, companyID)
if privileges.Invoicing {
    // User has invoicing privileges
}
```

### Privileges

The `CompanyPrivileges` struct contains permission flags:
- `Admin` - Administrative access
- `Company` - Company management
- `Consumer` - Consumer/customer access
- `Time` - Time tracking
- `Invoicing` - Invoice management
- `Accounting` - Accounting access
- `Supplier` - Supplier management
- `Salary` - Salary/payroll access

### Event Handling

Registers per-replica (transient) go-messaging-amqp consumers for privilege update events from the authz-service (`Setup()`), keeping the local privilege cache up-to-date. Each routing key gets its own queue, so events for one company arrive in any order — `Process` must never discard state it didn't itself record. `User.Added` therefore creates the company entry only when it is missing: a `Privilege.Added` processed ahead of it would otherwise be overwritten, and nothing re-reads the privilege until the next `Fetch()`. The converse doesn't hold yet — `setPrivileges` still creates an entry for a company it never saw a `User.Added` for, so a `Privilege.*` delivered after `User.Removed` resurrects an all-false membership. Don't combine `Setup()` with go-messaging-amqp's `WithReconnect`: a reconnect declares new per-replica queues, so revocations published during the outage are lost unless `Fetch()` runs again. Services exit on connection loss (`CloseListener`) and re-fetch on start.