diff --git a/api/v3/api_proto/hotlists.proto b/api/v3/api_proto/hotlists.proto
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+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+syntax = "proto3";
+
+package monorail.v3;
+
+option go_package = "api/v3/api_proto";
+
+import "api/v3/api_proto/feature_objects.proto";
+import "google/protobuf/field_mask.proto";
+import "google/protobuf/empty.proto";
+import "google/api/field_behavior.proto";
+import "google/api/resource.proto";
+
+// ***ONLY CALL rpcs WITH `status: {ALPHA|STABLE}`***
+// rpcs without `status` are not ready.
+
+// Hotlists service includes all methods needed for managing Hotlists.
+service Hotlists {
+  // status: NOT READY
+  // Creates a new hotlist.
+  //
+  // Raises:
+  //   NOT_FOUND if some given hotlist editors do not exist.
+  //   ALREADY_EXISTS if a hotlist with the same name owned by the user
+  //   already exists.
+  //   INVALID_ARGUMENT if a `hotlist.owner` is given.
+  rpc CreateHotlist (CreateHotlistRequest) returns (Hotlist) {}
+
+  // status: NOT READY
+  // Returns the requested Hotlist.
+  //
+  // Raises:
+  //   NOT_FOUND if the requested hotlist is not found.
+  //   PERMISSION_DENIED if the requester is not allowed to view the hotlist.
+  //   INVALID_ARGUMENT if the given resource name is not valid.
+  rpc GetHotlist (GetHotlistRequest) returns (Hotlist) {}
+
+  // status: NOT READY
+  // Updates a hotlist.
+  //
+  // Raises:
+  //   NOT_FOUND if the hotlist is not found.
+  //   PERMISSION_DENIED if the requester is not allowed to update the hotlist.
+  //   INVALID_ARGUMENT if required fields are missing.
+  rpc UpdateHotlist (UpdateHotlistRequest) returns (Hotlist) {}
+
+  // status: NOT READY
+  // Deletes a hotlist.
+  //
+  // Raises:
+  //   NOT_FOUND if the hotlist is not found.
+  //   PERMISSION_DENIED if the requester is not allowed to delete the hotlist.
+  rpc DeleteHotlist (GetHotlistRequest) returns (google.protobuf.Empty) {}
+
+  // status: NOT READY
+  // Returns a list of all HotlistItems in the hotlist.
+  //
+  // Raises:
+  //   NOT_FOUND if the parent hotlist is not found.
+  //   PERMISSION_DENIED if the requester is not allowed to view the hotlist.
+  //   INVALID_ARGUMENT if the page_token or given hotlist resource name is not
+  //   valid.
+  rpc ListHotlistItems (ListHotlistItemsRequest) returns (ListHotlistItemsResponse) {}
+
+  // status: NOT READY
+  // Reranks a hotlist's items.
+  //
+  // Raises:
+  //   NOT_FOUND if the hotlist or issues to rerank are not found.
+  //   PERMISSION_DENIED if the requester is not allowed to rerank the hotlist
+  //   or view issues they're trying to rerank.
+  //   INVALID_ARGUMENT if the `target_position` is invalid or `hotlist_items`
+  //   is empty or contains items not in the Hotlist.
+  rpc RerankHotlistItems (RerankHotlistItemsRequest) returns (google.protobuf.Empty) {}
+
+  // status: NOT READY
+  // Adds new items associated with given issues to a hotlist.
+  //
+  // Raises:
+  //   NOT_FOUND if the parent hotlist or issues are not found.
+  //   PERMISSION_DENIED if the requester is not allowed to edit the hotlist or
+  //   view issues they are trying to add.
+  //   INVALID_ARGUMENT if the `target_position` is invalid or `hotlist_items`
+  //   is empty or contains items not in the Hotlist.
+  rpc AddHotlistItems (AddHotlistItemsRequest) returns (google.protobuf.Empty) {}
+
+  // status: NOT READY
+  // Removes items associated with given issues from a hotlist.
+  //
+  // Raises:
+  //   NOT_FOUND if the parent hotlist or issues are not found.
+  //   PERMISSION_DENIED if the requester is not allowed to edit the hotlist or
+  //   view issues they are trying to remove.
+  //   INVALID_ARGUMENT if the `target_position` is invalid or `hotlist_items`
+  //   is empty or contains items not in the Hotlist.
+  rpc RemoveHotlistItems (RemoveHotlistItemsRequest) returns (google.protobuf.Empty) {}
+
+  // status: NOT READY
+  // Removes editors assigned to a hotlist.
+  //
+  // Raises:
+  //   NOT_FOUND if the hotlist is not found.
+  //   PERMISSION_DENIED if the requester is not allowed to remove all specified
+  //   editors from the hotlist.
+  //   INVALID_ARGUMENT if any specified editors are not in the hotlist.
+  rpc RemoveHotlistEditors (RemoveHotlistEditorsRequest) returns (google.protobuf.Empty) {}
+
+  // status: NOT READY
+  // Gathers all viewable hotlists that a user is a member of.
+  //
+  // Raises:
+  //   NOT_FOUND if the user is not found.
+  //   INVALID_ARGUMENT if the `user` is invalid.
+  rpc GatherHotlistsForUser (GatherHotlistsForUserRequest) returns (GatherHotlistsForUserResponse) {}
+}
+
+
+// Request message for CreateHotlist method.
+// Next available tag: 2
+message CreateHotlistRequest {
+  // The hotlist to create.
+  // `hotlist.owner` must be empty. The owner of the new hotlist will be
+  // set to the requester.
+  Hotlist hotlist = 1 [ (google.api.field_behavior) = REQUIRED ];
+}
+
+
+// Request message for GetHotlist method.
+// Next available tag: 2
+message GetHotlistRequest {
+  // The name of the hotlist to retrieve.
+  string name = 1 [
+      (google.api.field_behavior) = REQUIRED,
+      (google.api.resource_reference) = {type: "api.crbug.com/Hotlist"}];
+}
+
+
+// Request message for UpdateHotlist method.
+// Next available tag: 2
+message UpdateHotlistRequest {
+  // The hotlist's `name` field is used to identify the hotlist to be updated.
+  Hotlist hotlist = 1 [
+      (google.api.field_behavior) = REQUIRED,
+      (google.api.resource_reference) = {type: "api.crbug.com/Hotlist"} ];
+  // The list of fields to be updated.
+  google.protobuf.FieldMask update_mask = 2 [ (google.api.field_behavior) = REQUIRED ];
+}
+
+
+// Request message for ListHotlistItems method.
+// Next available tag: 5
+message ListHotlistItemsRequest {
+  // The parent hotlist, which owns this collection of items.
+  string parent = 1 [
+      (google.api.field_behavior) = REQUIRED,
+      (google.api.resource_reference) = {type: "api.crbug.com/Hotlist"} ];
+  // The maximum number of items to return. The service may return fewer than
+  // this value.
+  // If unspecified, at most 1000 items will be returned.
+  // The maximum value is 1000; values above 1000 will be coerced to 1000.
+  int32 page_size = 2;
+  // The string of comma separated field names used to order the items.
+  // Adding '-' before a field, reverses the sort order.
+  // E.g. 'stars,-status' sorts the items by number of stars low to high, then
+  // status high to low.
+  // If unspecified, items will be ordered by their rank in the parent.
+  string order_by = 3;
+  // A page token, received from a previous `ListHotlistItems` call.
+  // Provide this to retrieve the subsequent page.
+  //
+  // When paginating, all other parameters provided to `ListHotlistItems` must
+  // match the call that provided the page token.
+  string page_token = 4;
+}
+
+
+// Response to ListHotlistItems call.
+// Next available tag: 3
+message ListHotlistItemsResponse {
+  // The items from the specified hotlist.
+  repeated HotlistItem items = 1;
+  // A token, which can be sent as `page_token` to retrieve the next page.
+  // If this field is omitted, there are no subsequent pages.
+  string next_page_token = 2;
+}
+
+
+// The request used to rerank a Hotlist.
+// Next available tag: 4
+message RerankHotlistItemsRequest {
+  // Resource name of the Hotlist to rerank.
+  string name = 1 [
+      (google.api.resource_reference) = {type: "api.crbug.com/Hotlist"},
+      (google.api.field_behavior) = REQUIRED ];
+  // HotlistItems to be moved. The order of `hotlist_items` will
+  // determine the order of these items after they have been moved.
+  // E.g. With items [a, b, c, d, e], moving [d, c] to `target_position` 3, will
+  // result in items [a, b, e, d, c].
+  repeated string hotlist_items = 2 [
+      (google.api.resource_reference) = {type: "api.crbug.com/HotlistItem"},
+      (google.api.field_behavior) = REQUIRED ];
+  // Target starting position of the moved items.
+  // `target_position` must be between 0 and (# hotlist items - # items being moved).
+  uint32 target_position = 3 [ (google.api.field_behavior) = REQUIRED ];
+}
+
+
+// Request message for an AddHotlistItems call.
+// Next available tag: 4
+message AddHotlistItemsRequest {
+  // Resource name of the Hotlist to add new items to.
+  string parent = 1 [
+      (google.api.field_behavior) = REQUIRED,
+      (google.api.resource_reference) = {type: "api.crbug.com/Hotlist"} ];
+  // Resource names of Issues to associate with new HotlistItems added to `parent`.
+  repeated string issues = 2 [
+      (google.api.field_behavior) = REQUIRED,
+      (google.api.resource_reference) = {type: "api.crbug.com/Issue"} ];
+  // Target starting position of the new items.
+  // `target_position` must be between [0 and # of items that currently exist in
+  // `parent`]. The request will fail if a specified `target_position` is outside
+  // of this range.
+  // New HotlistItems added to a non-last position of the hotlist will
+  // cause ranks of existing HotlistItems below `target_position` to be adjusted.
+  // If no `target_position` is given, new items will be added to the end of
+  // `parent`.
+  uint32 target_position = 3;
+}
+
+
+// Request message for a RemoveHotlistItems call.
+// Next available tag: 3
+message RemoveHotlistItemsRequest {
+  // Resource name of the Hotlist to remove items from.
+  string parent = 1 [
+      (google.api.field_behavior) = REQUIRED,
+      (google.api.resource_reference) = {type: "api.crbug.com/Hotlist"} ];
+  // Resource names of Issues associated with HotlistItems that should be removed.
+  repeated string issues = 2 [
+      (google.api.field_behavior) = REQUIRED,
+      (google.api.resource_reference) = {type: "api.crbug.com/Issue"} ];
+}
+
+
+// Request message for a RemoveHotlistEditors call.
+// Next available tag: 3
+message RemoveHotlistEditorsRequest {
+  // Resource name of the Hotlist to remove editors from.
+  string name = 1 [
+      (google.api.field_behavior) = REQUIRED,
+      (google.api.resource_reference) = {type: "api.crbug.com/Hotlist"} ];
+  // Resource names of Users associated with the hotlist that should be removed.
+  repeated string editors = 2 [
+      (google.api.field_behavior) = REQUIRED,
+      (google.api.resource_reference) = {type: "api.crbug.com/User"} ];
+}
+
+
+// Request message for a GatherHotlistsForUser call.
+// Next available tag: 2
+message GatherHotlistsForUserRequest {
+  // Resource name of the user whose hotlists we want to fetch.
+  string user = 1 [ (google.api.field_behavior) = REQUIRED,
+      (google.api.resource_reference) = {type: "api.crbug.com/User"} ];
+}
+
+
+// Response message for a GatherHotlistsForUser call.
+// Next available tag: 2
+message GatherHotlistsForUserResponse {
+  repeated Hotlist hotlists = 1;
+}
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