feat(discord): add exec approval forwarding to DMs (#1621)

* feat(discord): add exec approval forwarding to DMs

Add support for forwarding exec approval requests to Discord DMs,
allowing users to approve/deny command execution via interactive buttons.

Features:
- New DiscordExecApprovalHandler that connects to gateway and listens
  for exec.approval.requested/resolved events
- Sends DMs with embeds showing command details and 3 buttons:
  Allow once, Always allow, Deny
- Configurable via channels.discord.execApprovals with:
  - enabled: boolean
  - approvers: Discord user IDs to notify
  - agentFilter: only forward for specific agents
  - sessionFilter: only forward for matching session patterns
- Updates message embed when approval is resolved or expires

Also fixes exec completion routing: when async exec completes after
approval, the heartbeat now uses a specialized prompt to ensure the
model relays the result to the user instead of responding HEARTBEAT_OK.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* feat: generic exec approvals forwarding (#1621) (thanks @czekaj)

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Co-authored-by: Peter Steinberger <steipete@gmail.com>

src/gateway/server-methods/exec-approval.ts

@@ -1,4 +1,5 @@
 import type { ExecApprovalDecision } from "../../infra/exec-approvals.js";
+import type { ExecApprovalForwarder } from "../../infra/exec-approval-forwarder.js";
 import type { ExecApprovalManager } from "../exec-approval-manager.js";
 import {
   ErrorCodes,
@@ -9,7 +10,10 @@ import {
 } from "../protocol/index.js";
 import type { GatewayRequestHandlers } from "./types.js";
 
-export function createExecApprovalHandlers(manager: ExecApprovalManager): GatewayRequestHandlers {
+export function createExecApprovalHandlers(
+  manager: ExecApprovalManager,
+  opts?: { forwarder?: ExecApprovalForwarder },
+): GatewayRequestHandlers {
   return {
     "exec.approval.request": async ({ params, respond, context }) => {
       if (!validateExecApprovalRequestParams(params)) {
@@ -69,6 +73,16 @@ export function createExecApprovalHandlers(manager: ExecApprovalManager): Gatewa
         },
         { dropIfSlow: true },
       );
+      void opts?.forwarder
+        ?.handleRequested({
+          id: record.id,
+          request: record.request,
+          createdAtMs: record.createdAtMs,
+          expiresAtMs: record.expiresAtMs,
+        })
+        .catch((err) => {
+          context.logGateway?.error?.(`exec approvals: forward request failed: ${String(err)}`);
+        });
       const decision = await decisionPromise;
       respond(
         true,
@@ -112,6 +126,11 @@ export function createExecApprovalHandlers(manager: ExecApprovalManager): Gatewa
         { id: p.id, decision, resolvedBy, ts: Date.now() },
         { dropIfSlow: true },
       );
+      void opts?.forwarder
+        ?.handleResolved({ id: p.id, decision, resolvedBy, ts: Date.now() })
+        .catch((err) => {
+          context.logGateway?.error?.(`exec approvals: forward resolve failed: ${String(err)}`);
+        });
       respond(true, { ok: true }, undefined);
     },
   };

src/gateway/server.impl.ts

@@ -43,6 +43,7 @@ import {
 import { startGatewayDiscovery } from "./server-discovery-runtime.js";
 import { ExecApprovalManager } from "./exec-approval-manager.js";
 import { createExecApprovalHandlers } from "./server-methods/exec-approval.js";
+import { createExecApprovalForwarder } from "../infra/exec-approval-forwarder.js";
 import type { startBrowserControlServerIfEnabled } from "./server-browser.js";
 import { createChannelManager } from "./server-channels.js";
 import { createAgentEventHandler } from "./server-chat.js";
@@ -396,7 +397,10 @@ export async function startGatewayServer(
   void cron.start().catch((err) => logCron.error(`failed to start: ${String(err)}`));
 
   const execApprovalManager = new ExecApprovalManager();
-  const execApprovalHandlers = createExecApprovalHandlers(execApprovalManager);
+  const execApprovalForwarder = createExecApprovalForwarder();
+  const execApprovalHandlers = createExecApprovalHandlers(execApprovalManager, {
+    forwarder: execApprovalForwarder,
+  });
 
   const canvasHostServerPort = (canvasHostServer as CanvasHostServer | null)?.port;