fix: route discord native subagent announce to channel target

src/auto-reply/reply/commands-subagents-spawn.test.ts

@@ -155,6 +155,8 @@ describe("/subagents spawn command", () => {
     const params = buildCommandTestParams("/subagents spawn beta do the thing", baseCfg, {
       CommandSource: "native",
       CommandTargetSessionKey: "agent:main:main",
+      OriginatingChannel: "discord",
+      OriginatingTo: "channel:12345",
     });
     params.sessionKey = "agent:main:slack:slash:u1";
 
@@ -164,6 +166,8 @@ describe("/subagents spawn command", () => {
     expect(result?.reply?.text).toContain("Spawned subagent beta");
     const [, spawnCtx] = spawnSubagentDirectMock.mock.calls[0];
     expect(spawnCtx.agentSessionKey).toBe("agent:main:main");
+    expect(spawnCtx.agentChannel).toBe("discord");
+    expect(spawnCtx.agentTo).toBe("channel:12345");
   });
 
   it("returns forbidden for unauthorized cross-agent spawn", async () => {

src/auto-reply/reply/commands-subagents.ts

@@ -686,9 +686,9 @@ export const handleSubagentsCommand: CommandHandler = async (params, allowTextCo
       { task, agentId, model, thinking, cleanup: "keep", expectsCompletionMessage: true },
       {
         agentSessionKey: requesterKey,
-        agentChannel: params.command.channel,
+        agentChannel: params.ctx.OriginatingChannel ?? params.command.channel,
         agentAccountId: params.ctx.AccountId,
-        agentTo: params.command.to,
+        agentTo: params.ctx.OriginatingTo ?? params.command.to,
         agentThreadId: params.ctx.MessageThreadId,
         agentGroupId: params.sessionEntry?.groupId ?? null,
         agentGroupChannel: params.sessionEntry?.groupChannel ?? null,

src/discord/monitor/native-command.ts

@@ -790,6 +790,11 @@ async function dispatchDiscordCommandInteraction(params: {
     Timestamp: Date.now(),
     CommandAuthorized: commandAuthorized,
     CommandSource: "native" as const,
+    // Native slash contexts use To=slash:<user> for interaction routing.
+    // For follow-up delivery (for example subagent completion announces),
+    // preserve the real Discord target separately.
+    OriginatingChannel: "discord" as const,
+    OriginatingTo: isDirectMessage ? `user:${user.id}` : `channel:${channelId}`,
   });
 
   const { onModelSelected, ...prefixOptions } = createReplyPrefixOptions({