feat: add channel canvas frontend support (#130)

desktop/src/shared/api/tauri.ts

@@ -3,6 +3,7 @@ import { invoke as tauriInvoke } from "@tauri-apps/api/core";
 import type {
   AddChannelMembersInput,
   AddChannelMembersResult,
+  CanvasResponse,
   Channel,
   ChannelDetail,
   ChannelMember,
@@ -23,6 +24,8 @@ import type {
   SearchMessagesInput,
   SearchMessagesResponse,
   SendChannelMessageResult,
+  SetCanvasInput,
+  SetCanvasResult,
   SetPresenceResult,
   SetChannelPurposeInput,
   SetChannelTopicInput,
@@ -280,6 +283,17 @@ type RawManagedAgentPrereqs = {
   mcp: RawCommandAvailability;
 };
 
+type RawCanvasResponse = {
+  content: string | null;
+  updated_at: number | null;
+  author: string | null;
+};
+
+type RawSetCanvasResult = {
+  ok: boolean;
+  event_id: string;
+};
+
 function toTauriError(error: unknown): Error {
   if (error instanceof Error) {
     return error;
@@ -588,6 +602,30 @@ export async function leaveChannel(channelId: string): Promise<void> {
   await invokeTauri("leave_channel", { channelId });
 }
 
+export async function getCanvas(channelId: string): Promise<CanvasResponse> {
+  const response = await invokeTauri<RawCanvasResponse>("get_canvas", {
+    channelId,
+  });
+  return {
+    content: response.content,
+    updatedAt: response.updated_at,
+    author: response.author,
+  };
+}
+
+export async function setCanvas(
+  input: SetCanvasInput,
+): Promise<SetCanvasResult> {
+  const response = await invokeTauri<RawSetCanvasResult>("set_canvas", {
+    channelId: input.channelId,
+    content: input.content,
+  });
+  return {
+    ok: response.ok,
+    eventId: response.event_id,
+  };
+}
+
 export async function getHomeFeed(
   input: GetHomeFeedInput = {},
 ): Promise<HomeFeedResponse> {

desktop/src/shared/api/types.ts

@@ -65,6 +65,22 @@ export type SetChannelPurposeInput = {
   purpose: string;
 };
 
+export type CanvasResponse = {
+  content: string | null;
+  updatedAt: number | null;
+  author: string | null;
+};
+
+export type SetCanvasInput = {
+  channelId: string;
+  content: string;
+};
+
+export type SetCanvasResult = {
+  ok: boolean;
+  eventId: string;
+};
+
 export type AddChannelMembersInput = {
   channelId: string;
   pubkeys: string[];