refactor(channels): drop agent-row rendering superseded by #3380

#3380 landed on main after this branch was cut and already renders agent
thread rows (author_kind on TaskThreadMessage, robot avatar + "Agent" label,
no hover menu) inside ThreadMessageRow. Remove this branch's parallel copy:
the duplicated TaskThreadMessage fields the rebase glued in, the separate
AgentThreadRow component, and isAgentThreadMessage, whose only consumer was
that branch. Keep the TaskThreadMessageEvent union and point the existing
event field at it — the one piece #3380 didn't cover.

Generated-By: PostHog Code
Task-Id: a0f85df1-4a8f-4467-8051-e471b5e95009

Author: adboio

packages/core/src/canvas/threadTimeline.test.ts

@@ -3,7 +3,6 @@ import {
   buildThreadTimeline,
   deriveThreadAgentStatus,
   hasAgentMention,
-  isAgentThreadMessage,
   normalizeAgentPromptText,
   shouldSuspendThreadSession,
   visibleThreadMessages,
@@ -170,18 +169,6 @@ describe("shouldSuspendThreadSession", () => {
   });
 });
 
-describe("isAgentThreadMessage", () => {
-  it.each([
-    { author_kind: "agent", expected: true },
-    { author_kind: "human", expected: false },
-    { author_kind: "system", expected: false },
-    // Older payloads predate agent rows; absent means human.
-    { author_kind: undefined, expected: false },
-  ])("author_kind $author_kind → $expected", ({ author_kind, expected }) => {
-    expect(isAgentThreadMessage({ author_kind })).toBe(expected);
-  });
-});
-
 describe("visibleThreadMessages", () => {
   const human = { id: "h", author_kind: "human" as const };
   const turn = (runId: string, id = `turn-${runId}`) => ({

packages/core/src/canvas/threadTimeline.ts

@@ -143,17 +143,6 @@ export function shouldSuspendThreadSession({
   return !isCloud && !hasRun && !hasSession;
 }
 
-/**
- * Agent rows are authorless by design, so anything reading `author` alone sees
- * nobody and calls them "Unknown". `author_kind` is the only thing that says
- * the agent wrote it.
- */
-export function isAgentThreadMessage(message: {
-  author_kind?: string;
-}): boolean {
-  return message.author_kind === "agent";
-}
-
 /**
  * The durable thread messages worth rendering, given the run whose turns the
  * viewer is already watching stream.

packages/shared/src/domain-types.ts

@@ -126,16 +126,12 @@ export interface TaskThreadMessage {
   /** Who authored the row; agent rows are server-emitted announcements. Absent on older backends. */
   author_kind?: "human" | "system" | "agent";
   /** Stable event key for non-human rows (e.g. "canvas_created", "turn_complete"). */
-  event?: string;
+  event?: TaskThreadMessageEvent | string;
   /** Structured event payload; turn_complete carries `{ run_id }` so a client rendering a run's live agent turns can dedupe the durable row. */
   payload?: Record<string, unknown>;
   content: string;
   created_at: string;
   author?: UserBasic | null;
-  author_kind?: "human" | "system" | "agent";
-  /** Empty for human messages. */
-  event?: TaskThreadMessageEvent | string;
-  payload?: Record<string, unknown>;
   forwarded_to_agent_at?: string | null;
   forwarded_by?: UserBasic | null;
 }

packages/ui/src/features/canvas/components/ThreadPanel.tsx

@@ -11,7 +11,6 @@ import {
   buildThreadTimeline,
   deriveThreadAgentStatus,
   hasAgentMention,
-  isAgentThreadMessage,
   normalizeAgentPromptText,
   shouldSuspendThreadSession,
   type ThreadAgentMessage,
@@ -187,50 +186,6 @@ export function ThreadMessageRow({
   );
 }
 
-/**
- * A durable row the agent posted — its final turn, or a question it needs
- * answered. Authorless by design, so it names itself rather than resolving an
- * author (which would read as "Unknown").
- *
- * Renders `content` through MentionText, not markdown: the server writes the
- * body with a real mention token for the task creator, and markdown would spell
- * that token out instead of chipping it.
- *
- * No hover menu — there's nothing to forward to the agent (it *is* the agent),
- * and its rows aren't the reader's to delete.
- */
-function AgentThreadRow({
-  message,
-  currentUserEmail,
-}: {
-  message: TaskThreadMessage;
-  currentUserEmail?: string | null;
-}) {
-  return (
-    <ThreadItem>
-      <ThreadItemGutter>
-        <Avatar size="lg" className="sticky top-2">
-          <AvatarFallback>
-            <RobotIcon size={14} />
-          </AvatarFallback>
-        </Avatar>
-      </ThreadItemGutter>
-      <ThreadItemContent>
-        <ThreadItemHeader>
-          <ThreadItemAuthor>Agent</ThreadItemAuthor>
-          <ThreadTimestamp dateTime={message.created_at} />
-        </ThreadItemHeader>
-        <ThreadItemBody>
-          <MentionText
-            content={message.content}
-            currentUserEmail={currentUserEmail}
-          />
-        </ThreadItemBody>
-      </ThreadItemContent>
-    </ThreadItem>
-  );
-}
-
 function agentPrompts(items: ConversationItem[]): ThreadAgentMessage[] {
   const prompts: ThreadAgentMessage[] = [];
   for (const item of items) {
@@ -454,29 +409,19 @@ function ThreadTimeline({
             author={taskAuthor}
           />
         ) : row.kind === "human" ? (
-          // A durable row the agent wrote — authorless, so the human row would
-          // credit it to "Unknown".
-          isAgentThreadMessage(row.message.value ?? {}) ? (
-            <AgentThreadRow
-              key={row.message.id}
-              message={row.message.value as TaskThreadMessage}
-              currentUserEmail={currentUserEmail}
-            />
-          ) : (
-            <ThreadMessageRow
-              key={row.message.id}
-              message={row.message.value as TaskThreadMessage}
-              isTaskAuthor={isTaskAuthor}
-              isOwnMessage={
-                !!currentUserUuid &&
-                currentUserUuid === row.message.value?.author?.uuid
-              }
-              currentUserEmail={currentUserEmail}
-              canForward={canForward}
-              onSendToAgent={() => onSendToAgent(row.message.id)}
-              onDelete={() => onDelete(row.message.id)}
-            />
-          )
+          <ThreadMessageRow
+            key={row.message.id}
+            message={row.message.value as TaskThreadMessage}
+            isTaskAuthor={isTaskAuthor}
+            isOwnMessage={
+              !!currentUserUuid &&
+              currentUserUuid === row.message.value?.author?.uuid
+            }
+            currentUserEmail={currentUserEmail}
+            canForward={canForward}
+            onSendToAgent={() => onSendToAgent(row.message.id)}
+            onDelete={() => onDelete(row.message.id)}
+          />
         ) : (
           <AgentTurnRow
             key={row.message.id}