fix(slack): prevent duplicate messages and use Slack date formatting

- Skip text forwarder for Slack when execApprovals buttons are enabled
- Use <!date^timestamp^{time}|fallback> for localized expiry time

src/infra/exec-approval-forwarder.ts

@@ -158,6 +158,30 @@ function defaultResolveSessionTarget(params: {
   };
 }
 
+function isSlackExecApprovalsEnabled(cfg: ClawdbotConfig, accountId?: string | null): boolean {
+  const slackCfg = cfg.channels?.slack as
+    | {
+        execApprovals?: { enabled?: boolean; approvers?: Array<string | number> };
+        accounts?: Record<
+          string,
+          { execApprovals?: { enabled?: boolean; approvers?: Array<string | number> } }
+        >;
+      }
+    | undefined;
+  if (!slackCfg) return false;
+  // Check account-specific config first
+  if (accountId && slackCfg.accounts?.[accountId]?.execApprovals?.enabled) {
+    const approvers = slackCfg.accounts[accountId].execApprovals?.approvers;
+    return Array.isArray(approvers) && approvers.length > 0;
+  }
+  // Fall back to top-level config
+  if (slackCfg.execApprovals?.enabled) {
+    const approvers = slackCfg.execApprovals?.approvers;
+    return Array.isArray(approvers) && approvers.length > 0;
+  }
+  return false;
+}
+
 async function deliverToTargets(params: {
   cfg: ClawdbotConfig;
   targets: ForwardTarget[];
@@ -169,6 +193,10 @@ async function deliverToTargets(params: {
     if (params.shouldSend && !params.shouldSend()) return;
     const channel = normalizeMessageChannel(target.channel) ?? target.channel;
     if (!isDeliverableMessageChannel(channel)) return;
+    // Skip Slack text messages when Slack exec approval buttons are enabled
+    if (channel === "slack" && isSlackExecApprovalsEnabled(params.cfg, target.accountId)) {
+      return;
+    }
     try {
       await params.deliver({
         cfg: params.cfg,

src/slack/monitor/exec-approvals.ts

@@ -72,7 +72,9 @@ function formatApprovalBlocks(request: ExecApprovalRequest) {
   const commandText = request.request.command;
   const commandPreview =
     commandText.length > 2000 ? `${commandText.slice(0, 2000)}...` : commandText;
+  const expiresAtUnix = Math.floor(request.expiresAtMs / 1000);
   const expiresIn = Math.max(0, Math.round((request.expiresAtMs - Date.now()) / 1000));
+  const fallbackTime = new Date(request.expiresAtMs).toISOString();
 
   const contextParts: string[] = [];
   if (request.request.cwd) contextParts.push(`*CWD:* ${request.request.cwd}`);
@@ -116,7 +118,12 @@ function formatApprovalBlocks(request: ExecApprovalRequest) {
 
   blocks.push({
     type: "context",
-    elements: [{ type: "mrkdwn", text: `Expires in ${expiresIn}s | ID: \`${request.id}\`` }],
+    elements: [
+      {
+        type: "mrkdwn",
+        text: `Expires <!date^${expiresAtUnix}^{time}|${fallbackTime}> (${expiresIn}s) | ID: \`${request.id}\``,
+      },
+    ],
   });
 
   blocks.push({