Finalize conversation and execution group documentation

docs/integrations/openai-compatible-chat.md

@@ -93,6 +93,8 @@ target's model must be available.
 Each ordinary message contains its `role` and string `content`. A
 cache-controlled message instead uses a text content block containing `type`,
 `text`, and `cache_control`; an empty cache-control TTL is omitted.
+For a continuation, captured history precedes the new definition and appended
+messages. Ancestry is local metadata and is not an upstream request field.
 
 Promptkit sends only `developer`, `system`, `user`, and `assistant` roles and
 does so without provider-specific translation. Tool and deprecated function