Stable and preview operations

Every operation is either stable or preview. A stable operation is the launch surface: build on it. A preview operation ships and works, but it is not a commitment. It may change shape or be removed without notice.

Where you see it

The marker is one field on the operation, and everything you read derives from it, so nothing disagrees:

Where	What it shows
API reference	Every preview operation is also listed under the Preview (unstable) tag, with `[Preview]` before its summary and a one-sentence warning first in its description.
OpenAPI document	`x-nicia-stability: preview` on the operation. Stable operations carry no such field.
TypeScript client	`stability` on the operation in the generated manifest, and a `@preview` line in the hover documentation of the method and its types.
These docs	A Preview aside on every section that documents a preview operation.

What is preview today

Durable branches and Proposals. Creating, inspecting, writing, comparing, archiving, restoring or destroying a branch; opening, listing, inspecting, revising or closing a Proposal.
Governed definitions. Inspecting, proposing and reviewing inferred definitions.
Part of the change lifecycle. Selecting a subset of a change, scheduling and cancelling one, and reading its journal.
Sources and snapshots. Listing and reading sources, and opening, adding to, sealing, reading, applying and cancelling a snapshot.
The text a receipt pinned. Reading the document text behind a receipt.
Queryable receipts. Listing receipts, and who was served a record, a document, or a source’s document.
Events and webhooks. Reading the event stream, including the record.affirmed event for a committed affirmation, and creating, listing and deleting the webhooks that push it.

Everything else is stable: documents, records, statements, context, query and search, changes with approve, reject and publish, reading a receipt and what changed since it, the schema, and keys.