feat(routing): add thread parent binding inheritance for Discord (#3892)

* feat(routing): add thread parent binding inheritance for Discord

When a Discord thread message doesn't match a direct peer binding,
now checks if the parent channel has a binding and uses that agent.

This enables multi-agent setups where threads inherit their parent
channel's agent binding automatically.

Changes:
- Add parentPeer parameter to ResolveAgentRouteInput
- Add binding.peer.parent match type
- Resolve thread parent early in Discord preflight
- Pass parentPeer to resolveAgentRoute for threads

Fixes thread routing in Discord multi-agent configurations where
threads were incorrectly routed to the default agent instead of
inheriting from their parent channel's binding.

* ci: trigger fresh macOS runners

* Discord: inherit thread bindings in reactions

* fix: add changelog for thread parent binding (#3892) (thanks @aerolalit)

---------

Co-authored-by: Lalit Singh <lalit@clawd.bot>
Co-authored-by: OSS Agent <oss-agent@clawdbot.ai>
Co-authored-by: Shadow <shadow@clawd.bot>

src/routing/resolve-route.ts

@@ -22,6 +22,8 @@ export type ResolveAgentRouteInput = {
   channel: string;
   accountId?: string | null;
   peer?: RoutePeer | null;
+  /** Parent peer for threads — used for binding inheritance when peer doesn't match directly. */
+  parentPeer?: RoutePeer | null;
   guildId?: string | null;
   teamId?: string | null;
 };
@@ -37,6 +39,7 @@ export type ResolvedAgentRoute = {
   /** Match description for debugging/logging. */
   matchedBy:
     | "binding.peer"
+    | "binding.peer.parent"
     | "binding.guild"
     | "binding.team"
     | "binding.account"
@@ -212,6 +215,15 @@ export function resolveAgentRoute(input: ResolveAgentRouteInput): ResolvedAgentR
     }
   }
 
+  // Thread parent inheritance: if peer (thread) didn't match, check parent peer binding
+  const parentPeer = input.parentPeer
+    ? { kind: input.parentPeer.kind, id: normalizeId(input.parentPeer.id) }
+    : null;
+  if (parentPeer && parentPeer.id) {
+    const parentPeerMatch = bindings.find((b) => matchesPeer(b.match, parentPeer));
+    if (parentPeerMatch) return choose(parentPeerMatch.agentId, "binding.peer.parent");
+  }
+
   if (guildId) {
     const guildMatch = bindings.find((b) => matchesGuild(b.match, guildId));
     if (guildMatch) {