feat: wire multi-agent config and routing

Co-authored-by: Mark Pors <1078320+pors@users.noreply.github.com>

docs/tools/subagents.md

@@ -30,13 +30,13 @@ Tool params:
 - `cleanup?` (`delete|keep`, default `keep`)
 
 Allowlist:
-- `routing.agents.<agentId>.subagents.allowAgents`: list of agent ids that can be targeted via `agentId` (`["*"]` to allow any). Default: only the requester agent.
+- `agents.list[].subagents.allowAgents`: list of agent ids that can be targeted via `agentId` (`["*"]` to allow any). Default: only the requester agent.
 
 Discovery:
 - Use `agents_list` to see which agent ids are currently allowed for `sessions_spawn`.
 
 Auto-archive:
-- Sub-agent sessions are automatically archived after `agent.subagents.archiveAfterMinutes` (default: 60).
+- Sub-agent sessions are automatically archived after `agents.defaults.subagents.archiveAfterMinutes` (default: 60).
 - Archive uses `sessions.delete` and renames the transcript to `*.deleted.<timestamp>` (same folder).
 - `cleanup: "delete"` archives immediately after announce (still keeps the transcript via rename).
 - Auto-archive is best-effort; pending timers are lost if the gateway restarts.
@@ -67,9 +67,15 @@ Override via config:
 
 ```json5
 {
-  agent: {
+  agents: {
+    defaults: {
+      subagents: {
+        maxConcurrent: 1
+      }
+    }
+  },
+  tools: {
     subagents: {
-      maxConcurrent: 1,
       tools: {
         // deny wins
         deny: ["gateway", "cron"],
@@ -85,7 +91,7 @@ Override via config:
 
 Sub-agents use a dedicated in-process queue lane:
 - Lane name: `subagent`
-- Concurrency: `agent.subagents.maxConcurrent` (default `1`)
+- Concurrency: `agents.defaults.subagents.maxConcurrent` (default `1`)
 
 ## Limitations