fix: document bare 402 fallback handling

CHANGELOG.md

@@ -1928,6 +1928,7 @@ Docs: https://docs.openclaw.ai
 - Gateway/websocket pairing bypass for disabled auth: skip device-pairing enforcement for Control UI operator sessions when `gateway.auth.mode=none`, so reverse-proxied dashboards no longer get stuck on `pairing required` despite auth being explicitly disabled. (#47148) Thanks @ademczuk.
 - Agents/usage tracking: stop forcing `supportsUsageInStreaming: false` on non-native OpenAI-completions providers so compatible backends report token usage and cost again instead of showing all zeros. (#46500) Fixes #46142. Thanks @ademczuk.
 - ACP/acpx: keep plugin-local backend installs under the bundled ACPX plugin package in live repo checkouts so rebuilds no longer delete the runtime binary, and avoid package-lock churn during runtime repair.
+- Agents/fallback: recognize bare leading ZenMux `402 ...` quota-refresh errors without misclassifying plain numeric `402 ...` text, and keep the embedded fallback regression coverage stable. (#47579) Thanks @bwjoke.
 - Agents/compaction: rerun transcript repair after `session.compact()` so orphaned `tool_result` blocks cannot survive compaction and break later Anthropic requests. (#16095) thanks @claw-sylphx.
 - Agents/compaction: trigger overflow recovery from the tool-result guard once post-compaction context still exceeds the safe threshold, so long tool loops compact before the next model call hard-fails. (#29371) thanks @keshav55.
 - macOS/exec approvals: harden exec-host request HMAC verification to use a timing-safe compare and keep malformed or truncated signatures fail-closed in focused IPC auth coverage.