Add typed artifact codec foundation

docs/internal/pipeline.md

@@ -53,7 +53,15 @@ runtime sensitive-data handling belongs in [Operations](../operations.md).
 `pipeline.Registries` holds constructors used during execution.
 `pipeline.ModuleCatalog` exposes their specs during configuration validation and
 resolution. Separate registries exist for every stage and for validators;
-`ValidatorChainRegistry` stores production default-chain mappings.
+`ValidatorChainRegistry` stores production default-chain mappings. Both
+containers also carry an `ArtifactCodecRegistry`. Generic registration records
+one codec per stable artifact kind, validates its schema metadata and JSON
+Schema, retains the exact schema digest and Go type, and safely encodes or
+decodes framework-erased values with typed errors on incompatibility.
+
+Production composition initializes the artifact codec registry without adding
+codec entries. The resolver and runner do not consult it yet, and production
+lanes remain on the raw artifact path.
 
 A `ModuleSpec` declares its stage plus required and provided capabilities.
 Chunk, extract, merge, and normalize specs may also declare reference slots.
@@ -183,6 +191,8 @@ durable manifest and logical file schemas are defined in the
 - `internal/core/config/effective_config_test.go`: config-to-resolution boundary.
 - `internal/framework/pipeline/profile_test.go`: selection, defaults,
   capabilities, validator chains, and digest behavior.
+- `internal/framework/pipeline/artifact_codec_registry_test.go`: typed codec
+  metadata, registration, erasure safety, strict decoding, and cloning.
 - `internal/framework/pipeline/references_test.go`: target resolution and
   materialization.
 - `internal/framework/pipeline/runner_test.go`: stage transitions, retries,