Function decode_meta 

pub fn decode_meta(payload: &[u8]) -> Option<LspCompletionMeta>

CSM.8b: LspCompletionMeta + LSP_COMPLETION_KIND_ID moved into lattice-lsp::completion so the type lives in the crate that owns lsp-types. The host imports them via this re-export – candidate payloads carry the serde- encoded form directly (encode_meta / decode_meta) so the parallel App.insert_completion_lsp_meta sidecar is gone; the candidate IS the metadata. Decode a payload produced by encode_meta. Returns None when the bytes don’t deserialise as LspCompletionMeta – the candidate’s kind_id may not be ours (plugin source colliding on the kind, or a stray payload), or the wire format may have drifted across versions.