fix(config): recover critical config clobbers

docs/gateway/configuration.md

@@ -100,6 +100,9 @@ The Gateway also keeps a trusted last-known-good copy after a successful startup
 `openclaw.json` is later changed outside OpenClaw and no longer validates, startup
 and hot reload preserve the broken file as a timestamped `.clobbered.*` snapshot,
 restore the last-known-good copy, and log a loud warning with the recovery reason.
+Startup read recovery also treats sharp size drops, missing config metadata, and a
+missing `gateway.mode` as critical clobber signatures when the last-known-good
+copy had those fields.
 If a status/log line is accidentally prepended before an otherwise valid JSON
 config, gateway startup and `openclaw doctor --fix` can strip the prefix,
 preserve the polluted file as `.clobbered.*`, and continue with the recovered

docs/gateway/troubleshooting.md

@@ -303,6 +303,7 @@ Common signatures:
 - `.clobbered.*` exists → an external direct edit or startup read was restored.
 - `.rejected.*` exists → an OpenClaw-owned config write failed schema or clobber checks before commit.
 - `Config write rejected:` → the write tried to drop required shape, shrink the file sharply, or persist invalid config.
+- `missing-meta-vs-last-good`, `gateway-mode-missing-vs-last-good`, or `size-drop-vs-last-good:*` → startup treated the current file as clobbered because it lost fields or size compared with the last-known-good backup.
 - `Config last-known-good promotion skipped` → the candidate contained redacted secret placeholders such as `***`.
 
 Fix options: