Beta API: Sessions endpoint replaced by Memory Stores; webhook schemas gain required field

BreakingBreaking change

This is a breaking change — integrations that rely on the affected behaviour will need updates before the change rolls out.

What changed

Several significant breaking changes are present in this beta API update:

/v1/sessions?beta=true (POST) has been replaced by /v1/memory_stores/{memory_store_id}/memories?beta=true (POST) — the old session creation endpoint no longer exists; any integrations calling it will break.
Webhook event data schemas BetaWebhookSessionThreadCreatedEventData, BetaWebhookSessionThreadIdledEventData, and BetaWebhookSessionThreadTerminatedEventData now include session_thread_id as a required field — consumers that validate or deserialize these payloads strictly may break if they were not already handling this field.
New schemas and endpoints for memory stores, deployments, vaults, and related resources have been added (additive), alongside new error types like vault_archived_error, vault_not_found_error, and workspace_archived_error.