Simplify contextual entity grounding

docs/roadmap/implementation.md

@@ -274,8 +274,9 @@ path.
    registry and the current `*source.SourceDocument`. Its API must provide:
    - a cloned `contracts.LLMInputMaterial` for the `location_registry` slot;
    - deterministic resolution of a returned selector to one cloned
-     `dnd.Location`; and
-   - the digest of the exact model projection.
+     `dnd.Location`.
+   The prompt material's existing `Digest` field owns the digest of the exact
+   model projection; do not expose a second grounding-specific digest API.
 4. Construct the projection in registry order. Group entries by the existing
    location comparison key:
    - every projection entry has exactly the required fields `name`,
@@ -299,10 +300,10 @@ path.
 7. Separate deterministic identity fingerprinting from LLM material. Add
    `IdentityDigest()` over the registry's ordered `{id,name}` identity
    projection, and update the location normalizer and registry-validator
-   checkpoint consumers to use it. The new operation grounding owns the model
-   projection digest. Retain the old ID-bearing prompt accessor only as a
-   documented transitional dependency of the still-unchanged location
-   occurrence extractor; do not add new callers.
+   checkpoint consumers to use it. The new operation grounding carries the
+   model projection digest in its `LLMInputMaterial`. Retain the old ID-bearing
+   prompt accessor only as a documented transitional dependency of the
+   still-unchanged location occurrence extractor; do not add new callers.
 8. Add focused tests for unique names, same-name context and selectors,
    canonical range order, deterministic projection/digest, defensive copies,
    exact selector resolution, nil/foreign/invalid references, selector
@@ -367,10 +368,12 @@ remove durable location IDs from the prompt and private response.
 7. Change `mappingPolicy` to
    `dnd.location_occurrences.extract_mapping.v2`.
 8. Remove the legacy ID-bearing registry `PromptInput` and its model-projection
-   digest once the extractor uses operation grounding. Update the occurrence
-   checkpoint to combine `IdentityDigest()` with the new grounding projection
-   digest, prompt/schema fingerprint, mapping policy, and its existing inputs;
-   do not retain dead compatibility aliases.
+   digest once the extractor uses operation grounding. Keep the occurrence's
+   static module fingerprint based on `IdentityDigest()`, prompt/schema
+   fingerprints, and mapping policy. The operation-scoped projection is already
+   covered by source/chunk identity and configured or generated reference
+   dependencies, while its `LLMInputMaterial.Digest` identifies the exact model
+   input; do not add a second digest API or operation-aware static fingerprint.
 9. Update focused schema, prompt, extractor, canonicalization, checkpoint, and
    generated-reference tests. Cover unique-name empty selectors, successful
    same-name selection, failure for an unsupported ambiguous mention,