diff --git a/.openclaw-sync/source.json b/.openclaw-sync/source.json
index e67ee159d..3076a90dd 100644
--- a/.openclaw-sync/source.json
+++ b/.openclaw-sync/source.json
@@ -1,5 +1,5 @@
 {
   "repository": "openclaw/openclaw",
-  "sha": "583b41982781df5132d84470a69ba5661cd597c6",
-  "syncedAt": "2026-04-28T05:31:51.573Z"
+  "sha": "d48c3e12a5d896cbdad3e7fcf5bba2af644a9ca5",
+  "syncedAt": "2026-04-28T05:34:31.416Z"
 }
diff --git a/docs/plugins/compatibility.md b/docs/plugins/compatibility.md
index 2f08bd886..b0359f479 100644
--- a/docs/plugins/compatibility.md
+++ b/docs/plugins/compatibility.md
@@ -136,7 +136,8 @@ Current compatibility records include:
   move to `openclaw/plugin-sdk/channel-route`
 - activation hints that are being replaced by manifest contribution ownership
 - deprecated implicit startup sidecar loading for plugins that have not declared
-  `activation.onStartup`
+  `activation.onStartup`; maintainers can test the future stricter behavior with
+  `OPENCLAW_DISABLE_LEGACY_IMPLICIT_STARTUP_SIDECARS=1`
 - `setup-api` runtime fallback while setup descriptors move to cold
   `setup.requiresRuntime: false` metadata
 - provider `discovery` hooks while provider catalog hooks move to
diff --git a/docs/plugins/manifest.md b/docs/plugins/manifest.md
index 794d6bfcb..963163be2 100644
--- a/docs/plugins/manifest.md
+++ b/docs/plugins/manifest.md
@@ -268,6 +268,12 @@ plugins unless they declare `activation.onStartup: true`. Plugin status and
 compatibility reports warn with `legacy-implicit-startup-sidecar` when a plugin
 still relies on that fallback.
 
+For migration testing, set
+`OPENCLAW_DISABLE_LEGACY_IMPLICIT_STARTUP_SIDECARS=1` to disable only that
+deprecated fallback. This opt-in mode does not block explicit
+`activation.onStartup: true` plugins or plugins loaded by channel, config,
+agent-harness, memory, or other narrower activation triggers.
+
 ```json
 {
   "activation": {