Document contextual help link contract

README.md

@@ -106,3 +106,6 @@ excluded from the user projection.
 - `docs/DOCUMENTATION_LAYER_CONCEPT.md` defines the configured, available, and evidence documentation model.
 - `docs/INSTANCE_AWARE_DOCUMENTATION.md` defines the runtime context and condition model.
 - `docs/DOCUMENTATION_EXPERIENCE_CONCEPT.md` defines the workflow, structure/reference, and design-pattern documentation experience.
+- Core's `DocumentationHelpLink` is the stable route/field/blocker entry point
+  into a topic or help context, with hosted fallback when this module is not
+  active.

docs/DOCUMENTATION_EXPERIENCE_CONCEPT.md

@@ -184,6 +184,15 @@ Each topic should support stable anchors and related-topic links:
 - pattern topics link to examples and the components that implement them
 - unavailable topics link to the blocker and the actor who can resolve it
 
+Core exposes `DocumentationHelpLink` for those entry points. A caller supplies
+either a stable topic id (`/docs?type=user&topic=...`) or help-context id
+(`/docs?type=user&context=...`), plus an optional topic anchor. Route help uses
+the context form; field labels and blocker callouts can use either form. The
+component opens the configured Help Center when Docs is active and falls back
+to the hosted documentation site when the optional module is absent. Modules
+must reference topic/context ids, not reproduce Docs routing or inspect another
+module's implementation.
+
 ## Source Contract Direction
 
 The current `DocumentationTopic` contract can carry the first version through