Slug taken

ERR-P01-IDT-3110 - Slug taken

Summary

The requested agent slug is well-formed but already belongs to another agent.

When this is raised

• On POST /v1/agent/register, the (valid) slug collides with an existing agent row. Slugs are globally unique.
• Distinct from ERR-P01-IDT-2002 (the slug fails the pattern); here the shape is fine but the name is occupied.

What to do

• Choose a different slug and retry.
• Slugs are never recycled implicitly - if you control the existing agent and want the name, revoke or rename it first (admin surface).

Server-side cause

• Raised by: packages/identity/src/service/register.ts - register (slug uniqueness check).
• Guard: if (existing[0]) throw new RegisterError('slug_taken', 'slug already in use', { slug }); mapped to IDENTITY_ERR.slug_taken (409) in packages/identity/src/router/register.ts.

Example response

{
  "type":      "https://citizenry.id/errors/ERR-P01-IDT-3110",
  "title":     "Conflict",
  "status":    409,
  "code":      "ERR-P01-IDT-3110",
  "message":   "slug already in use",
  "detail":    { "slug": "atlas" },
  "method":    "POST",
  "instance":  "/v1/agent/register",
  "request_url": "https://api.citizenry.id/v1/agent/register",
  "timestamp": "2026-05-17T07:00:00.000Z"
}

Related codes

• ERR-P01-IDT-2002 - slug invalid (bad shape).
• ERR-P01-IDT-3100 - email already in use.

Changelog

• 0.1.0 - introduced.