perf(meta-push): use cached api.config instead of deprecated loadConfig()

`pushMetaToMonitor` and `resolveAgentId` were both calling
`api.runtime?.config?.loadConfig?.()` to read the agent list. That
deprecated path (openclaw warns at gateway start:
"plugin runtime config.loadConfig() is deprecated; use config.current()")
synchronously rebuilds the full plugin-metadata snapshot — realpathSync
walks every plugin's package.json + manifest + source up the directory
tree, hashWatchedFiles fingerprints every watched plugin file, and
discoverInDirectory re-scans every `dist/extensions/<plugin>` (~100 of
them on prod t2). Each rebuild costs ~6-7s of gateway CPU.

`pushMetaToMonitor` fires every `reportIntervalSec` (default 30s)
from `hooks/gateway-start.js`. With 100 plugins that put the gateway
into a chronic ~22-30% CPU baseline even with zero agent activity. V8
profile 2026-05-27 08:14:00 60s window (0 turns, 2 metadata pushes
during): lstat 44.2%, statSync(buildInstalledManifestRegistryIndexKey)
6.9%, hashWatchedFiles via memo key 1.7%, all routed through
`readPersistedInstalledPluginIndexInstallRecordsSync` -> per-plugin
`discoverInDirectory`.

Switching to `(api as any).config ?? api.runtime?.config?.loadConfig?.()`
reads from the snapshot cache the gateway already maintains — the same
pattern already used elsewhere in this file (e.g. the calendar wakeAgent
dispatcher at line 284). Same change applied to `resolveAgentId` (only
runs once at start, but same anti-pattern).

This is a plugin-side perf workaround. The underlying openclaw bug is
that `loadConfig()` rebuilds the snapshot rather than returning the
cached one — a chronic 'all sync cache validity checks pay the full
discovery cost' design issue worth pushing upstream separately (the
walks per-call cost we measured here is unrelated to and amplifies any
agent-turn-triggered walk path).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

plugin/index.ts

@@ -128,7 +128,9 @@ function register(api: PluginAPI): void {
     /** Resolve agent ID from env, config, or fallback. */
     function resolveAgentId(): string {
       if (process.env.AGENT_ID) return process.env.AGENT_ID;
-      const cfg = api.runtime?.config?.loadConfig?.();
+      // Read from cached `api.config` first — see pushMetaToMonitor for why
+      // the deprecated `api.runtime?.config?.loadConfig?.()` path is heavy.
+      const cfg = (api as any).config ?? api.runtime?.config?.loadConfig?.();
       return cfg?.agents?.list?.[0]?.id ?? cfg?.agents?.defaults?.id ?? 'unknown';
     }
 
@@ -184,6 +186,25 @@ function register(api: PluginAPI): void {
      * Push OpenClaw metadata to the Monitor bridge.
      * This enriches Monitor heartbeats with OpenClaw version/plugin/agent info.
      * Failures are non-fatal — Monitor continues to work without this data.
+     *
+     * IMPORTANT — read config from the cached `api.config` surface, NOT from
+     * the deprecated `api.runtime?.config?.loadConfig?.()` path. The
+     * deprecated path triggers a full plugin-metadata-snapshot rebuild on
+     * every call: realpathSync walks every plugin's package.json + manifest
+     * + source paths (lstats up the directory tree), `hashWatchedFiles`
+     * fingerprints all watched plugin files, and `discoverInDirectory`
+     * re-scans every `dist/extensions/<plugin>` dir. On t2 with ~100 plugins
+     * each rebuild costs ~6-7s of CPU; with this push firing every 30s
+     * (default reportIntervalSec) the chronic baseline was ~22-25% gateway
+     * CPU even with zero agent activity (V8 profile 2026-05-27 08:14:00 60s:
+     * lstat 44.2%, statSync 6.9%, hashWatchedFiles via memo key 1.7%, all
+     * routed through readPersistedInstalledPluginIndexInstallRecordsSync ->
+     * discoverInDirectory). Switching to `api.config` reads from the
+     * already-loaded snapshot cache; the elsewhere-in-this-file pattern was
+     * already `api.config ?? api.runtime?.config?.loadConfig?.()`.
+     *
+     * Same fix is applied to `resolveAgentId` below — that's read once at
+     * gateway start so the impact is smaller, but it's the same anti-pattern.
      */
     async function pushMetaToMonitor() {
       const bridgeClient = getBridgeClient();
@@ -191,7 +212,7 @@ function register(api: PluginAPI): void {
 
       let agentNames: string[] = [];
       try {
-        const cfg = api.runtime?.config?.loadConfig?.();
+        const cfg = (api as any).config ?? api.runtime?.config?.loadConfig?.();
         const agentsList = cfg?.agents?.list;
         if (Array.isArray(agentsList)) {
           agentNames = agentsList