[Fix] Fast mode repeats loading reactions during active Slack conversations

apps/api/src/handlers/fast-agent-entry.ts

@@ -3,6 +3,13 @@ import { Env } from '@roomote/env';
 
 type FastAgentEntryMode = 'explicit' | 'default';
 
+export function shouldShowFastAgentProcessingReaction(params: {
+  entryMode: FastAgentEntryMode;
+  hasExistingSession: boolean;
+}): boolean {
+  return params.entryMode === 'explicit' || !params.hasExistingSession;
+}
+
 export function resolveFastAgentEntryMode(params: {
   explicitInvocation: boolean;
   deploymentSettingEnabled: boolean;

apps/api/src/handlers/slack/events/fast-agent.ts

@@ -55,6 +55,7 @@ export async function processFastAgentMessage(params: {
   activeTasks?: FastAgentActiveTask[];
   launchTask: LaunchFastAgentTask;
   processingReactionName?: string;
+  showProcessingReaction?: boolean;
 }): Promise<void> {
   const {
     event,
@@ -67,6 +68,7 @@ export async function processFastAgentMessage(params: {
     activeTasks = [],
     launchTask,
     processingReactionName = 'eyes',
+    showProcessingReaction = true,
   } = params;
   const threadId = event.thread_ts || event.ts;
   const conversation = {
@@ -99,11 +101,13 @@ export async function processFastAgentMessage(params: {
   let didAddProcessingReaction = false;
 
   try {
-    didAddProcessingReaction = await slack.addReaction({
-      channel: event.channel,
-      timestamp: event.ts,
-      name: processingReactionName,
-    });
+    if (showProcessingReaction) {
+      didAddProcessingReaction = await slack.addReaction({
+        channel: event.channel,
+        timestamp: event.ts,
+        name: processingReactionName,
+      });
+    }
 
     if (!question) {
       await postSlackThreadMarkdownMessage({

apps/api/src/handlers/slack/events/message-entry.ts

@@ -59,7 +59,10 @@ import {
   isFastCommandInvocation,
   processFastAgentMessage,
 } from './fast-agent.js';
-import { resolveFastAgentEntryMode } from '../../fast-agent-entry.js';
+import {
+  resolveFastAgentEntryMode,
+  shouldShowFastAgentProcessingReaction,
+} from '../../fast-agent-entry.js';
 import { processSnapshotResume } from './snapshot-resume.js';
 import {
   dispatchSlackThreadFollowUp,
@@ -1258,6 +1261,22 @@ async function maybeHandleChannelAutoStart(params: {
       : null;
 
   if (fastAgentEntryMode && userMapping) {
+    const hasExistingSession =
+      fastAgentEntryMode === 'default' &&
+      (await hasFastAgentSession({
+        surface: 'slack',
+        workspaceId: context.teamId,
+        conversationId: channelAutoStartEvent.ts,
+        replyTarget: {
+          channelId: channelAutoStartEvent.channel,
+          threadId: channelAutoStartEvent.ts,
+        },
+      }));
+    const showProcessingReaction = shouldShowFastAgentProcessingReaction({
+      entryMode: fastAgentEntryMode,
+      hasExistingSession,
+    });
+
     startFastAgentResponse({
       event: { ...channelAutoStartEvent, user: channelAutoStartEvent.user },
       slackInstallation: context.slackInstallation,
@@ -1268,6 +1287,7 @@ async function maybeHandleChannelAutoStart(params: {
       usageText: 'Use `/fast <question>` in this channel.',
       continuation: fastAgentEntryMode === 'default',
       processingReactionName: ackEmoji,
+      showProcessingReaction,
       errorLogPrefix: `❌ Background fast-agent response failed for auto-start thread ${channelAutoStartEvent.ts}:`,
     });
 
@@ -1602,6 +1622,7 @@ function startFastAgentResponse(params: {
   continuation?: boolean;
   activeTasks?: { taskId: string }[];
   processingReactionName: string;
+  showProcessingReaction?: boolean;
   errorLogPrefix: string;
 }): void {
   const { errorLogPrefix, ...fastAgentParams } = params;
@@ -1741,6 +1762,19 @@ async function handleSlackEntryEvent(params: {
   });
 
   if (fastAgentEntryMode) {
+    const hasExistingSession =
+      fastAgentEntryMode === 'default' &&
+      (await hasFastAgentSession({
+        surface: 'slack',
+        workspaceId: teamId,
+        conversationId: threadId,
+        replyTarget: { channelId: event.channel, threadId },
+      }));
+    const showProcessingReaction = shouldShowFastAgentProcessingReaction({
+      entryMode: fastAgentEntryMode,
+      hasExistingSession,
+    });
+
     startFastAgentResponse({
       event,
       slackInstallation,
@@ -1751,6 +1785,7 @@ async function handleSlackEntryEvent(params: {
       activeTasks: activeRun ? [{ taskId: activeRun.taskId }] : [],
       continuation: fastAgentEntryMode === 'default',
       processingReactionName: ackEmoji,
+      showProcessingReaction,
       errorLogPrefix: `❌ Background fast-agent response failed for thread ${threadId}:`,
     });
 
@@ -1779,6 +1814,7 @@ async function handleSlackEntryEvent(params: {
       continuation: true,
       activeTasks: activeRun ? [{ taskId: activeRun.taskId }] : [],
       processingReactionName: ackEmoji,
+      showProcessingReaction: false,
       errorLogPrefix: `❌ Background fast-agent continuation failed for thread ${threadId}:`,
     });