Draft the initial protobuf changes

crates/rpc/proto/zed.proto

@@ -136,6 +136,9 @@ message Envelope {
         OnTypeFormattingResponse on_type_formatting_response = 112;
 
         UpdateWorktreeSettings update_worktree_settings = 113;
+
+        InlayHints inlay_hints = 114;
+        InlayHintsResponse inlay_hints_response = 115;
     }
 }
 
@@ -705,6 +708,62 @@ message OnTypeFormattingResponse {
     Transaction transaction = 1;
 }
 
+message InlayHints {
+    uint64 project_id = 1;
+    uint64 buffer_id = 2;
+    Anchor start = 3;
+    Anchor end = 4;
+    repeated VectorClockEntry version = 5;
+}
+
+message InlayHintsResponse {
+    repeated InlayHint hints = 1;
+    repeated VectorClockEntry version = 2;
+}
+
+message InlayHint {
+    Anchor position = 1;
+    InlayHintLabel label = 2;
+    optional string kind = 3;
+    InlayHintTooltip tooltip = 4;
+}
+
+message InlayHintLabel {
+    oneof label {
+        string value = 1;
+        InlayHintLabelParts label_parts = 2;
+    }
+}
+
+message InlayHintLabelParts {
+    repeated InlayHintLabelPart parts = 1;
+}
+
+message InlayHintLabelPart {
+    string value = 1;
+    InlayHintLabelPartTooltip tooltip = 2;
+    Location location = 3;
+}
+
+message InlayHintTooltip {
+    oneof content {
+        string value = 1;
+        MarkupContent markup_content = 2;
+    }
+}
+
+message InlayHintLabelPartTooltip {
+    oneof content {
+        string value = 1;
+        MarkupContent markup_content = 2;
+    }
+}
+
+message MarkupContent {
+    string kind = 1;
+    string value = 2;
+}
+
 message PerformRenameResponse {
     ProjectTransaction transaction = 2;
 }