docs(requirements): reconcile cross-references for Site Call Audit

docs/requirements/HighLevelReqs.md

@@ -231,7 +231,7 @@ Scripts executing on a site for a given instance can:
 - **Write** attribute values on that instance. For attributes with a data source reference, the write goes to the Data Connection Layer which writes to the physical device; the in-memory value updates when the device confirms the new value via the existing subscription. For static attributes, the write updates the in-memory value and **persists the override to local SQLite** — the value survives restart and failover. Persisted overrides are reset when the instance is redeployed.
 - **Call other scripts** on that instance via `Instance.CallScript("scriptName", params)`. Calls use the Akka ask pattern and return the called script's return value. Script-to-script calls support concurrent execution.
 - **Call shared scripts** via `Scripts.CallShared("scriptName", params)`. Shared scripts execute **inline** in the calling Script Actor's context — they are compiled code libraries, not separate actors.
-- **Call external system API methods** in two modes: `ExternalSystem.Call()` for synchronous request/response, or `ExternalSystem.CachedCall()` for fire-and-forget with store-and-forward on transient failure (see Section 5).
+- **Call external system API methods** in two modes: `ExternalSystem.Call()` for synchronous request/response, or `ExternalSystem.CachedCall()` for deferred delivery — it returns a `TrackedOperationId` tracking handle immediately and store-and-forwards the call on transient failure (see Section 5).
 - **Send notifications** (see Section 6).
 - **Access databases** by requesting an MS SQL client connection by name (see Section 5.5).