feat: add live-cycling LSP completion

src/plugin.rs

@@ -105,6 +105,24 @@ pub struct SemanticToken {
     pub modifiers: u16,
 }
 
+/// A completion replacement in zero-based, end-exclusive grapheme coordinates.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct CompletionEdit {
+    pub start: TextPosition,
+    pub end: TextPosition,
+    pub text: String,
+}
+
+/// Protocol-independent completion text and its atomic document edits.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct CompletionItem {
+    pub label: String,
+    pub detail: Option<String>,
+    /// Index of the primary replacement; other edits never determine caret placement.
+    pub primary_edit: usize,
+    pub edits: Vec<CompletionEdit>,
+}
+
 #[derive(Debug, Deserialize)]
 #[serde(tag = "type", rename_all = "snake_case", deny_unknown_fields)]
 pub enum UpdateEffect {
@@ -132,6 +150,12 @@ pub enum UpdateEffect {
         revision: u64,
         text: String,
     },
+    #[serde(skip_deserializing)]
+    Completion {
+        buffer_id: usize,
+        revision: u64,
+        items: Vec<CompletionItem>,
+    },
     Message {
         text: String,
     },