Expand module contracts for references and normalizer LLM access

docs/internal/pipeline.md

@@ -74,9 +74,10 @@ Every production module registers a `ModuleSpec` with:
 - `Provides`: capabilities added after that module runs;
 - `Requires`: capabilities that must already be available.
 
-Extractor specs may also declare reference slots. Slot declarations are
-available from registry metadata without constructing extractor instances.
-Non-extractor module specs must not declare reference slots.
+Chunk, extract, and normalize specs may also declare reference slots. Slot
+declarations are available from registry metadata without constructing module
+instances. Input, merge, validate, and output specs must not declare reference
+slots.
 
 Capability checks prevent incompatible pipeline composition before a run starts.
 
@@ -114,10 +115,10 @@ The runner:
 ## Chunk Results
 
 Chunkers implement `contracts.Chunker` and receive a `contracts.ChunkRequest`
-with the validated source document, the structured LLM client, the configured
-LLM profile, module options, and run metadata. Deterministic and LLM-backed
-chunkers use the same contract; provider construction stays outside chunk
-modules.
+with the validated source document, reference set, structured LLM client, the
+configured LLM profile, module options, and run metadata. Deterministic and
+LLM-backed chunkers use the same contract; provider construction stays outside
+chunk modules.
 
 After `Chunk` returns, the runner appends chunker warnings before returning any
 chunker error. When chunking succeeds, the runner validates generic chunk