Add merge references and retry config

docs/internal/llm.md

@@ -41,6 +41,10 @@ The runtime records the actual selected Scriptorium profile, provider, and model
 used during execution. Manifest population does not rely on a precomputed
 profile ID before pipeline execution.
 
+Explicit profile validation and `--llm-profile` overrides apply to LLM-capable
+pipeline stages: chunk, extract, merge, and normalize. Input, output, and
+validator bindings are not part of the current production LLM profile scope.
+
 ## Scriptorium Adapter
 
 `ScriptoriumClient` implements `contracts.StructuredLLMClient` by converting