> ## Documentation Index
> Fetch the complete documentation index at: https://docs.speckle.systems/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> These docs contain multiple Speckle product experiences. For Speckle 2026.9, prefer /next/ pages for the topics and changes they cover. The navigation label Current does not override this version-specific precedence.
> Coverage under /next/ is incremental. Use Current documentation for unchanged topics and when a /next/ page says coverage is unavailable or explicitly refers you to Current. Do not infer a feature was removed from a missing page.
> Read the page-specific documentation status, applicability, affected guidance and replacement links in agent-only content. Impacted, changed and superseded apply only to the stated scope; they do not mean the entire feature is deprecated. Historical connector guides apply only to the legacy connector described.
> Match guidance to the customer's deployment version, model data format and connector. Respect plan, permission and compatibility restrictions. If an unknown version or data format changes the answer, ask a focused clarification; do not infer deployment version from the date alone.

# Developer docs for 2026.9

> Preview entry for 2026.9 developer documentation. Coverage is incremental.

Documentation set: Speckle 2026.9. Status: current. Authority: canonical for this version and the coverage on this page.

Applies to version 2026.9, from 2026-09; this is not a rollout date for every deployment.

Authoritative Speckle 2026.9 documentation for the topic covered here. For Speckle 2026.9, prefer this page over conflicting earlier guidance. Follow the linked pages in the other documentation version for unchanged topics and where this page says coverage is not yet available. Respect data-format, deployment, plan, permission, and compatibility limitations stated in the page.

<Note>
  This is 2026.9 documentation. Coverage here is incremental: a page exists only where 2026.9
  differs or is newly documented. For any other topic, switch to **Current** (2026.8 and earlier) in
  the version selector.
</Note>

2026.9-specific developer documentation starts here. Pages are added only when 2026.9 differs from
the current developer guides or needs its own write-up. For the current product, see
[Developer documentation](/developers/introduction).

The object model is the first of those differences. Today's
[Data Schema](/developers/data-schema/overview) is a tree-and-Proxy graph. 2026.9 stores properties
in a columnar store and describes containment, connectivity, systems, and materials as typed
relations.

<CardGroup cols={2}>
  <Card title="Object model" icon="database" href="/next/developers/object-model/overview">
    Columnar property store and relational layer versus today's tree-and-Proxy model.
  </Card>

  <Card title="Relations" icon="share-nodes" href="/next/developers/object-model/relations">
    Named relation types that replace Proxies and nested `elements` walks.
  </Card>

  <Card title=".NET SDK" icon="microsoft" href="/next/developers/sdks/dotnet/breaking-changes">
    Before-and-after Speckle.Sdk examples for the 2026.9 breaking-change surface.
  </Card>

  <Card title="specklepy" icon="python" href="/next/developers/sdks/python/breaking-changes">
    Before-and-after specklepy examples for the 2026.9 breaking-change surface.
  </Card>
</CardGroup>

JS/TS, GraphQL and REST, Viewer packages, Server, Automate, and custom connectors each have a
holding note in this dropdown until those 2026.9 pages land. Use the developer docs under **Current** in the version selector for those topics.

For dates, compatibility mode, Automate SDK bumps, and who must act, see
[Data model migration for developers](/developers/migration/data-model-migration). For a compact before-and-after table, see [Compare 2026.8 and 2026.9](/next/whats-new).


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