Module help_host 

CR.3: the help guest→host topic-registration seam. The help guest→host topic-registration seam (CR.3).

Design: contributable-registries.md §3.1, and the help WIT interface.

A help-contributing plugin implements the help-plugin world: it imports the help API (register-topic) and exports register-help-topics, which the host calls once to drive declaration. The theme-plugin precedent, shape for shape.

What this module does NOT do

It does not touch lattice-help. The seam collects plain [HelpTopicSpec] values and hands them back; lattice-plugin-loader turns them into HelpTopics and RCU-registers them into the HelpTopicRegistryHandle. That keeps the dependency pointing the way it already does — the loader is the crate that knows about the editor’s native registries, the host is the crate that knows about wasm — and costs nothing, because a help body is inert data on both sides of that line.

Namespacing is host-side, from host ground truth

[namespaced_topic_name] derives the registered name from the manifest id the HOST holds, never from anything the guest passes. A guest cannot name a topic outside its own namespace, so collisions with builtins and between plugins are structurally impossible rather than a policy the loader has to enforce and a user has to debug.

Structs

HelpTopicSpec

One topic a guest declared, ready for the loader to register.

Functions

namespaced_topic_name

The registered name for a topic a plugin declared.

validate_topic

Validate a guest’s topic declaration, or reject it.