generated: '2026-08-25'
method: searched
source: >-
  https://wiki.secondlife.com/wiki/APIs_and_Web_Services_Portal and the individual
  Linden Lab Official API pages beneath it, corroborated by live probes of
  api.secondlife.com and cap.secondlife.com on 2026-08-25.
note: >-
  There are no cross-cutting conventions at Linden Lab, and that is the finding.
  The Second Life API surface is four unrelated services accreted over roughly two
  decades — a 2007-era capability system, a set of flat-text and LLSD statistics
  feeds, a modern JSON key-authenticated lookup endpoint, and a merchant callback —
  and they share no auth model, no serialization format, no error envelope, no
  pagination scheme and no versioning scheme. An agent cannot learn one and apply
  it to the next.
auth_style:
  summary: three unrelated models; see authentication/linden-lab-authentication.yml
  models: [api-key header, unguessable capability URL, anonymous]
  bearer_tokens: false
  oauth2: false
serialization:
  request:
    - api: Second Life Name to Agent ID API
      format: application/json
    - api: Second Life Registration API
      format: application/llsd+xml
    - api: Second Life Inventory API
      format: LLSD
  response:
    - api: Second Life Name to Agent ID API
      format: application/json
    - api: Second Life Live Data Feeds
      formats:
        - text/plain (newline-delimited key/value pairs — key on one line, value on the next)
        - text/xml (a bare <stats> document)
        - application/llsd+xml (LLSD map)
  note: >-
    LLSD (Linden Lab Structured Data) is the house serialization format and is
    genuinely specified and openly implemented — see the first-party `llsd` PyPI
    package and https://wiki.secondlife.com/wiki/LLSD. The .txt feeds are the
    outlier: they are not JSON, not CSV, and not key=value — they alternate a key
    line and a value line, which any generic parser will get wrong.
idempotency:
  supported: false
  header: null
  detail: >-
    No idempotency key, no request-deduplication contract, and no retry-safety
    guidance anywhere on the Second Life API surface. The one non-trivial write
    operation — Registration API create_user — is documented as failing with code
    71 "user exists" on a repeat, which is a uniqueness constraint rather than an
    idempotency guarantee: a retry after a timeout cannot be distinguished from a
    duplicate attempt by the caller.
  applicable: true
pagination:
  supported: false
  detail: >-
    No paginated collection endpoint exists. The Inventory API's
    FetchInventoryDescendents2 returns a full descendents list per folder with a
    `descendents` count and a `version` integer, but exposes no cursor, no limit
    and no offset. The data feeds return fixed-size documents.
field_expansion:
  supported: false
sparse_fieldsets:
  supported: false
metadata:
  supported: false
request_id:
  supported: true
  header: x-ll-request-id
  direction: response
  detail: >-
    Every api.secondlife.com response carries an x-ll-request-id (observed on both
    a 400 and a 200 on 2026-08-25). It is not documented anywhere, and no docs page
    tells a caller to quote it in a support ticket — but it is the only tracing
    handle the surface gives you.
  method: probed
versioning:
  in_url: false
  in_header: false
  detail: see lifecycle/linden-lab-lifecycle.yml
error_envelope:
  consistent: false
  detail: see errors/linden-lab-error-codes.yml — the two documented APIs use different shapes
rate_limit_signaling:
  headers: []
  detail: >-
    No RateLimit-*, X-RateLimit-* or Retry-After header on any response. The one
    published limit (2 req/s on get_agent_id) is discoverable only by reading the
    wiki. See rate-limits/linden-lab-rate-limits.yml.
dry_run_mode:
  supported: false
  detail: >-
    No dry-run, preview or validate-only mode on any endpoint. The nearest thing is
    the Registration API's `check_name` capability, which tests username
    availability without creating an account — a purpose-built pre-flight for one
    field, not a general dry-run.
  partial: check_name capability (Registration API)
reversibility:
  grade: none
  applicable: true
  detail: >-
    Linden Lab documents no reversal operation, and no reversal window, for any
    write on its API surface. This is recorded as a real absence, not as an
    unmeasured field: the wiki pages for the Registration API, the Inventory API
    and the Marketplace ANS were each read on 2026-08-25 and none names a cancel,
    undo, void, refund, reverse, rollback or restore operation, and none states a
    period inside which an action can be taken back. No window is asserted here
    because none is published.
  write_surfaces:
    - operation: create_user (Registration API capability)
      creates: a Second Life account
      reversal_operation: null
      window: null
      grade: none
      note: >-
        Account creation is not reversible through the API. Account closure is a
        support-desk action performed by the account holder through
        accounts.secondlife.com, not an API call available to the integrator that
        created the account.
    - operation: add_to_group (Registration API capability)
      creates: group membership for an avatar
      reversal_operation: null
      window: null
      grade: none
      note: >-
        No remove_from_group capability is published. Group membership is removed
        in-world or via the viewer.
    - operation: Marketplace purchase (reported via ANS, not initiated by API)
      reversal_operation: Redelivery
      window: null
      grade: documented
      note: >-
        ANS transaction records carry a Type of either "Purchase" or "Redelivery",
        so a redelivery event is an observable corrective action in the notification
        stream. It is a re-send of purchased inventory, not a refund, and Linden Lab
        publishes no window inside which it can be requested. Graded `documented`
        rather than `verified` for exactly that reason — the path exists in the
        data, the window does not exist in the docs.
      source: https://wiki.secondlife.com/wiki/Direct_Delivery_and_Automatic_Notification_System
  read_only_surfaces:
    - Second Life Live Data Feeds
    - Second Life Name to Agent ID API
    - Second Life Map API
    - Second Life Inventory API (fetch-only capabilities)
cross_links:
  errors: errors/linden-lab-error-codes.yml
  lifecycle: lifecycle/linden-lab-lifecycle.yml
  authentication: authentication/linden-lab-authentication.yml
  rate_limits: rate-limits/linden-lab-rate-limits.yml
  webhooks: asyncapi/linden-lab-ans-webhooks.yml