Function slot_extract_content 

pub fn slot_extract_content(
    bits: u64,
    kind: NativeKind,
) -> (Option<Value>, Option<String>, Option<String>)

If the slot carries a renderable Content shape (Content node, DataTable, or TableView), return (content_json, content_html, content_terminal). Otherwise all three are None.

W18.2 (R8 — output-adapter integration): the kind-threaded content dispatch is rebuilt on top of the surviving 6-renderer infrastructure (TERMINAL / HTML / MARKDOWN / JSON / PLAIN). Slot bits are dispatched per HeapKind, the underlying typed payload is materialised as a ContentNode, and each renderer projects the node into its own output shape:

• JSON via crate::renderers::json::JsonRenderer parsed into serde_json::Value (the renderer guarantees valid JSON per the renderers::cross_renderer_tests::json_is_valid_json regression).
• HTML via crate::renderers::html::HtmlRenderer.
• Terminal via crate::renderers::terminal::TerminalRenderer (ANSI escapes; consumers route to PLAIN when the sink is non-TTY).

Pre-rebuild this function returned (None, None, None) for every Content-bearing slot per the Phase 1.B placeholder — that scar is resolved here.