> ## 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.

# Developer docs for 2026.9

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

<Note>
  This is 2026.9 preview documentation. Coverage here is incremental: a page exists only where
  2026.9 differs or is newly documented.
</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 Current developer docs for
those topics today.

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
Current versus 2026.9 table, see [Compare Current and 2026.9](/next/whats-new).