refactor: centralize message target resolution

Co-authored-by: Thinh Dinh <tobalsan@users.noreply.github.com>

src/channels/plugins/signal.ts

@@ -18,7 +18,10 @@ import {
 } from "./config-helpers.js";
 import { formatPairingApproveHint } from "./helpers.js";
 import { resolveChannelMediaMaxBytes } from "./media-limits.js";
-import { normalizeSignalMessagingTarget } from "./normalize-target.js";
+import {
+  looksLikeSignalTargetId,
+  normalizeSignalMessagingTarget,
+} from "./normalize-target.js";
 import { signalOnboardingAdapter } from "./onboarding/signal.js";
 import { PAIRING_APPROVED_MESSAGE } from "./pairing-message.js";
 import {
@@ -26,7 +29,6 @@ import {
   migrateBaseNameToDefaultAccount,
 } from "./setup-helpers.js";
 import type { ChannelPlugin } from "./types.js";
-import { missingTargetError } from "../../infra/outbound/target-errors.js";
 
 const meta = getChatChannelMeta("signal");
 
@@ -116,6 +118,8 @@ export const signalPlugin: ChannelPlugin<ResolvedSignalAccount> = {
   },
   messaging: {
     normalizeTarget: normalizeSignalMessagingTarget,
+    looksLikeTargetId: looksLikeSignalTargetId,
+    targetHint: "<E.164|group:ID|signal:group:ID|signal:+E.164>",
   },
   setup: {
     resolveAccountId: ({ accountId }) => normalizeAccountId(accountId),
@@ -197,16 +201,6 @@ export const signalPlugin: ChannelPlugin<ResolvedSignalAccount> = {
     deliveryMode: "direct",
     chunker: chunkText,
     textChunkLimit: 4000,
-    resolveTarget: ({ to }) => {
-      const trimmed = to?.trim();
-      if (!trimmed) {
-        return {
-          ok: false,
-          error: missingTargetError("Signal", "<E.164|group:ID|signal:group:ID|signal:+E.164>"),
-        };
-      }
-      return { ok: true, to: trimmed };
-    },
     sendText: async ({ cfg, to, text, accountId, deps }) => {
       const send = deps?.sendSignal ?? sendMessageSignal;
       const maxBytes = resolveChannelMediaMaxBytes({