Function instantiate_component 

pub async fn instantiate_component(
    engine: &Engine,
    component: &Component,
    linker: &Linker<HostState>,
    preopens: &[Preopen],
    grant_policy: &GrantPolicy,
    info: &ComponentInfo,
    max_memory: Option<usize>,
    prompter: Arc<dyn ConsentPrompter>,
    cache: Arc<DecisionCache>,
    credentials: Option<Arc<CredentialHost>>,
    audit: &AuditContext,
) -> Result<(ToolProvider, Option<SessionProvider>, Store<HostState>)>

Instantiate the component. Returns the tool-provider guest, an optional SessionProvider (present iff the component exports act:sessions/session-provider), and the store.

act-world declares both tool-provider and session-provider as exports, but the latter is opt-in. Rather than ActWorldIndices::new (which requires every declared export and would reject stateless components), each interface is bound through its own per-interface GuestIndices: tool-provider is mandatory, session-provider is looked up with .ok() so its absence yields None.

Component info is read from custom sections (no instantiation needed for that).