diff --git a/src/app/components/signal-board/signal-board.css b/src/app/components/signal-board/signal-board.css
index 9441de0..13e20b4 100644
--- a/src/app/components/signal-board/signal-board.css
+++ b/src/app/components/signal-board/signal-board.css
@@ -168,7 +168,8 @@
 }
 
 .jira-comment-section,
-.github-comment-section {
+.github-comment-section,
+.slack-comment-section {
   display: flex;
   gap: 0.5rem;
   width: 100%;
@@ -176,7 +177,8 @@
 }
 
 .jira-comment-section input,
-.github-comment-section input {
+.github-comment-section input,
+.slack-comment-section input {
   flex: 1;
   border: 1px solid #cbd5e1;
   border-radius: 999px;
@@ -187,7 +189,8 @@
 }
 
 .jira-comment-section input:focus,
-.github-comment-section input:focus {
+.github-comment-section input:focus,
+.slack-comment-section input:focus {
   border-color: #6366f1;
 }
 
diff --git a/src/app/components/signal-board/signal-board.html b/src/app/components/signal-board/signal-board.html
index c041f58..72ba03c 100644
--- a/src/app/components/signal-board/signal-board.html
+++ b/src/app/components/signal-board/signal-board.html
@@ -55,6 +55,11 @@ <h3>{{ signal.title }}</h3>
         <button type="button" class="ghost-btn" [disabled]="submittingGitHubComment[signal.id] || !githubComments[signal.id]" (click)="addGitHubComment(signal)">Comment</button>
       </div>
 
+      <div class="slack-comment-section" *ngIf="signal.sourceType === 'slack'">
+        <input type="text" placeholder="Reply to thread..." [(ngModel)]="slackReplies[signal.id]" [disabled]="submittingSlackReply[signal.id]">
+        <button type="button" class="ghost-btn" [disabled]="submittingSlackReply[signal.id] || !slackReplies[signal.id]" (click)="sendSlackReply(signal)">Reply</button>
+      </div>
+
       <div class="action-buttons-group">
         <a class="link-btn" *ngIf="signal.url" [href]="signal.url" target="_blank" rel="noreferrer">{{ getOpenLabel(signal) }}</a>
         <button type="button" class="ghost-btn" *ngIf="signal.sourceType === 'github'" (click)="toggleGitHubState(signal)">
diff --git a/src/app/components/signal-board/signal-board.ts b/src/app/components/signal-board/signal-board.ts
index 7dc7441..2f52588 100644
--- a/src/app/components/signal-board/signal-board.ts
+++ b/src/app/components/signal-board/signal-board.ts
@@ -198,4 +198,31 @@ export class SignalBoardComponent {
       }
     });
   }
+
+  slackReplies: { [signalId: string]: string } = {};
+  submittingSlackReply: { [signalId: string]: boolean } = {};
+
+  sendSlackReply(signal: Signal) {
+    const workspaceId = String(signal.workspaceId ?? '');
+    const channelId = String(signal.metadata['channel_id'] || signal.sourceId.split(':')[0]);
+    const threadTs = String(signal.metadata['ts'] || signal.externalId);
+    const text = this.slackReplies[signal.id];
+
+    if (!text || !text.trim() || !channelId || !threadTs) return;
+
+    this.submittingSlackReply[signal.id] = true;
+    this.integrationService.replyToSlack(workspaceId, channelId, threadTs, text).subscribe({
+      next: () => {
+        this.showToast('Reply sent to Slack thread');
+        this.slackReplies[signal.id] = '';
+        this.submittingSlackReply[signal.id] = false;
+        this.cdr.detectChanges();
+      },
+      error: () => {
+        this.showToast('Failed to send Slack reply');
+        this.submittingSlackReply[signal.id] = false;
+        this.cdr.detectChanges();
+      }
+    });
+  }
 }
diff --git a/src/app/components/workspace-integrations/workspace-integrations.html b/src/app/components/workspace-integrations/workspace-integrations.html
index 3ee89a3..8f4061b 100644
--- a/src/app/components/workspace-integrations/workspace-integrations.html
+++ b/src/app/components/workspace-integrations/workspace-integrations.html
@@ -26,6 +26,9 @@ <h3>Slack connection</h3>
     <div class="card-actions">
       <button *ngIf="!isSlackConnected" type="button" class="primary-btn slack-btn" (click)="connectSlack()">Connect Slack</button>
       <button *ngIf="isSlackConnected" type="button" class="secondary-btn" (click)="disconnectSlack()">Disconnect</button>
+      <button *ngIf="isSlackConnected" type="button" class="primary-btn slack-btn" [disabled]="isSlackSyncing" (click)="syncSlackNow()">
+        {{ isSlackSyncing ? 'Syncing...' : 'Sync Now' }}
+      </button>
     </div>
   </article>
 
@@ -60,8 +63,12 @@ <h3>Channel selection</h3>
 
   <section class="sync-card" *ngIf="isSlackConnected">
     <h3>Slack sync status</h3>
-    <p *ngIf="slackLastSyncAt">Last channel update: {{ slackLastSyncAt | date: 'medium' }}</p>
+    <p *ngIf="slackLastSyncAt">Last sync: {{ slackLastSyncAt | date: 'medium' }}</p>
     <p *ngIf="!slackLastSyncAt">No Slack sync has run yet.</p>
+    <p *ngIf="slackSyncStatus">
+      Current status:
+      <strong>{{ slackSyncStatus.status }}</strong>
+    </p>
   </section>
 
   <article class="integration-card">
diff --git a/src/app/components/workspace-integrations/workspace-integrations.ts b/src/app/components/workspace-integrations/workspace-integrations.ts
index 1cd37ab..37ffdad 100644
--- a/src/app/components/workspace-integrations/workspace-integrations.ts
+++ b/src/app/components/workspace-integrations/workspace-integrations.ts
@@ -24,9 +24,11 @@ export class WorkspaceIntegrationsComponent implements OnInit, OnDestroy {
   slackWorkspaceName = '';
   slackWorkspaceUrl = '';
   slackLastSyncAt?: Date;
+  slackSyncStatus?: SyncStatus;
   slackFeedbackMessage = '';
   slackErrorMessage = '';
   isSlackSaving = false;
+  isSlackSyncing = false;
 
   repos: GitHubRepo[] = [];
   selectedRepoIds: number[] = [];
@@ -178,6 +180,7 @@ export class WorkspaceIntegrationsComponent implements OnInit, OnDestroy {
         this.isSlackSaving = false;
         this.slackFeedbackMessage = 'Slack channel selection saved.';
         this.loadSlackChannels();
+        this.syncSlackNow(); // Trigger sync after saving selection
       },
       error: () => {
         this.isSlackSaving = false;
@@ -186,6 +189,25 @@ export class WorkspaceIntegrationsComponent implements OnInit, OnDestroy {
     });
   }
 
+  syncSlackNow(): void {
+    this.isSlackSyncing = true;
+    this.slackErrorMessage = '';
+    this.integrationService.syncSlack(this.workspaceId).subscribe({
+      next: (status) => {
+        this.slackSyncStatus = status;
+        this.isSlackSyncing = false;
+        this.slackFeedbackMessage = status.status === 'in_progress'
+          ? 'Slack sync started. Messages will refresh shortly.'
+          : 'Slack sync could not be started.';
+        this.loadSlackChannels();
+      },
+      error: (error: Error) => {
+        this.isSlackSyncing = false;
+        this.slackErrorMessage = error.message;
+      }
+    });
+  }
+
   saveRepoSelection(): void {
     this.isGitHubSaving = true;
     this.githubErrorMessage = '';
diff --git a/src/app/services/integration.service.ts b/src/app/services/integration.service.ts
index 923ce6d..10b6698 100644
--- a/src/app/services/integration.service.ts
+++ b/src/app/services/integration.service.ts
@@ -101,6 +101,20 @@ export class IntegrationService {
       );
   }
 
+  syncSlack(workspaceId: string): Observable<SyncStatus> {
+    const params = new HttpParams().set('workspace_id', workspaceId);
+    return this.http.post<GitHubSyncResponse>(`${this.apiUrl}/slack/sync`, {}, { params }).pipe(
+      map((response) => {
+        const status: SyncStatus['status'] = response.status === 'sync_started' ? 'in_progress' : 'failed';
+        return {
+          syncId: `sync-${Date.now()}`,
+          status,
+        };
+      }),
+      catchError((error) => throwError(() => toError(error, 'Unable to sync Slack.'))),
+    );
+  }
+
   disconnectSlack(workspaceId: string): Observable<void> {
     return this.getIntegrations(workspaceId).pipe(
       switchMap((integrations) => {
@@ -365,4 +379,15 @@ export class IntegrationService {
       }),
     );
   }
+
+  replyToSlack(workspaceId: string, channelId: string, threadTs: string, text: string): Observable<any> {
+    const params = new HttpParams().set('workspace_id', workspaceId);
+    return this.http.post(`${this.apiUrl}/integrations/slack/reply`, {
+      channel_id: channelId,
+      thread_ts: threadTs,
+      text: text
+    }, { params }).pipe(
+      catchError((error) => throwError(() => toError(error, 'Unable to send Slack reply.'))),
+    );
+  }
 }